首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   1574篇
  免费   144篇
  国内免费   24篇
耳鼻咽喉   2篇
儿科学   23篇
妇产科学   9篇
基础医学   110篇
口腔科学   10篇
临床医学   227篇
内科学   594篇
皮肤病学   19篇
神经病学   51篇
特种医学   27篇
外科学   42篇
综合类   109篇
一般理论   3篇
预防医学   365篇
眼科学   11篇
药学   70篇
中国医学   56篇
肿瘤学   14篇
  2024年   7篇
  2023年   44篇
  2022年   31篇
  2021年   118篇
  2020年   82篇
  2019年   48篇
  2018年   44篇
  2017年   48篇
  2016年   73篇
  2015年   107篇
  2014年   126篇
  2013年   156篇
  2012年   117篇
  2011年   120篇
  2010年   109篇
  2009年   113篇
  2008年   79篇
  2007年   51篇
  2006年   34篇
  2005年   37篇
  2004年   24篇
  2003年   30篇
  2002年   29篇
  2001年   10篇
  2000年   11篇
  1999年   14篇
  1998年   14篇
  1997年   6篇
  1996年   6篇
  1995年   10篇
  1994年   3篇
  1993年   5篇
  1992年   6篇
  1991年   6篇
  1990年   7篇
  1989年   6篇
  1988年   1篇
  1987年   4篇
  1986年   1篇
  1984年   2篇
  1983年   1篇
  1981年   1篇
  1980年   1篇
排序方式: 共有1742条查询结果,搜索用时 156 毫秒
61.
护士对医院伦理气氛认知现状调查分析   总被引:1,自引:0,他引:1  
目的了解护士对医院伦理气氛的认知现状并对其影响因素进行分析,为医院管理部门提高护士伦理气氛认知水平提供参考。方法采用伦理气氛认知量表(ECQ)对衡阳市某三甲医院348名注册护士进行调查。结果护士伦理气氛认知总均分为81.64±8.20,不同人事关系、第一学历、护龄及月收入的护士伦理气氛认知得分比较,差异有统计学意义(均P<0.05);护士对医院伦理气氛的认知受其月收入、第一学历的影响。结论医院管理者可通过增加护士人员编制,提高薪金待遇,加强在职人员伦理培训,从而提高护士对医院伦理气氛的认知水平。  相似文献   
62.
Background: Automobile exhaust contains precursors to ozone and fine particulate matter (PM ≤ 2.5 µm in aerodynamic diameter; PM2.5), posing health risks. Dependency on car commuting also reduces physical fitness opportunities.Objective: In this study we sought to quantify benefits from reducing automobile usage for short urban and suburban trips.Methods: We simulated census-tract level changes in hourly pollutant concentrations from the elimination of automobile round trips ≤ 8 km in 11 metropolitan areas in the upper midwestern United States using the Community Multiscale Air Quality (CMAQ) model. Next, we estimated annual changes in health outcomes and monetary costs expected from pollution changes using the U.S. Environmental Protection Agency Benefits Mapping Analysis Program (BenMAP). In addition, we used the World Health Organization Health Economic Assessment Tool (HEAT) to calculate benefits of increased physical activity if 50% of short trips were made by bicycle.Results: We estimate that, by eliminating these short automobile trips, annual average urban PM2.5 would decline by 0.1 µg/m3 and that summer ozone (O3) would increase slightly in cities but decline regionally, resulting in net health bene-fits of $4.94 billion/year [95% confidence interval (CI): $0.2 billion, $13.5 billion), with 25% of PM2.5 and most O3 bene-fits to populations outside metropolitan areas. Across the study region of approximately 31.3 million people and 37,000 total square miles, mortality would decline by approximately 1,295 deaths/year (95% CI: 912, 1,636) because of improved air quality and increased exercise. Making 50% of short trips by bicycle would yield savings of approximately $3.8 billion/year from avoided mortality and reduced health care costs (95% CI: $2.7 billion, $5.0 billion]. We estimate that the combined benefits of improved air quality and physical fitness would exceed $8 billion/year.Conclusion: Our findings suggest that significant health and economic benefits are possible if bicycling replaces short car trips. Less dependence on automobiles in urban areas would also improve health in downwind rural settings.  相似文献   
63.
Objective: To compare the health and well‐being of women by exposure to adverse climate events. An Exceptional Circumstance declaration (EC) was used as a proxy for adverse climate events. The Australian government may provide financial support to people living in EC areas, i.e. areas experiencing a one in 20–25 year event (drought, flood or fire) that results in a severe, extended downturn in farm or farm‐related income. Methods: Data from 6,584 53–58 year old non‐metropolitan women participating in the 2004 survey of the Australian Longitudinal Study on Women's Health (ALSWH) were linked to EC data. Generalised linear models were used to analyse differences in SF‐36 General Health (GH) and Mental Health (MH) and perceived stress by EC for all women. Models were adjusted for demographic, health‐related and psychosocial factors potentially on the pathway between EC and health. Given that the effects on health were expected to be greater in vulnerable people, analyses were repeated for women with worse socioeconomic circumstances. Results: GH, MH and stress did not differ for the 3,366 women in EC areas and 3,218 women in non‐EC areas. GH, MH and stress were worse among vulnerable women (who had difficulty managing on available income) regardless of EC. Conclusion and implications: This research adds to the existing literature on climate change, associated adverse climate events and health, by suggesting that multiple resources available in high income countries, including government support and individual psychosocial resources may mitigate some of the health impacts of adverse climate events, even among vulnerable people.  相似文献   
64.
目的研究产后大出血的临床表现,并通过不同的维护与治疗手段来研究正确、有效的预防方式,并为相应的产后大出血的急救以及避免提供可行的方案。方法针对我院从2008~2011年3年内收治的252例产后大出血的案例进行总结性分析,利用统计软件对其出血原因,临床表现等指标进行分析并找到相应的统计学依据。结果在针对不同的出血原因的分析方面得到因为子宫收缩异常而操作的产后大出血占到%的比例,由于胎盘异常而造成的产后大出血为5.6%的比例,由于软产道损伤而造成的产后大出血占到%的比例。结论针对对出血原因的判断在引产与接生的过程中进行及时的预判能够有效的增加对产后出血情况的预测进而降低由于产后出血带来的产妇死亡情况。  相似文献   
65.
目的对甘肃省卫生人力资源配置现状及公平性进行分析,对2019—2023年需求数量进行预测,为甘肃省卫生人力资源发展规划提供参考建议。方法运用洛伦兹曲线和基尼系数对甘肃省卫生人力资源配置的公平性进行研究;运用时间序列模型对甘肃省2019—2023年卫生人力资源需求量进行预测。结果 2018年甘肃省所属每千人口卫生技术人员、执业(助理)医师和注册护士分别为5.2名、2.0名和1.9名。按人口配置的基尼系数均小于0.4的临界值;按地理配置的基尼系数均超过0.6,处于高度不公平状态。预测到2023年甘肃省卫生技术人员、执业(助理)医师和注册护士的人数分别为167 471人、40 534人和53 657人。结论甘肃省卫生人力资源配置的人口公平性优于地理公平性;卫生人力资源发展速度缓慢,医护比不合理,全省医疗人力资源不足;甘肃省在未来五年对卫生人力资源的需求量很大,需要进一步重视卫生人力资源的开发,扩大人才队伍建设规模。  相似文献   
66.
Patient safety culture is a critical component of modern health care. However, the high‐paced, unpredictable nature of the emergency department (ED) environment may impact adversely on it. The aim of this paper is to explore the concept of patient safety culture as it may apply to emergency health care, and to propose a conceptual framework that could form the basis for interventions designed to improve it. This is a systematic review of the literature. A search was undertaken of common electronic bibliographic databases using key words such as safety culture, safety climate, and Emergency Department. Articles were analysed for consistent themes with the aim to construct a conceptual framework. Ten articles met the inclusion criteria that specifically examined safety culture in the ED. Synthesis of the literature resulted in the emergence of three overarching themes of ED practice found to impact on safety culture in the ED. These were the dimensions of patient safety culture, the factors influencing it, and the interventions for improving it. A conceptual framework was constructed that identifies elements that significantly impact the patient safety culture in the ED. This framework may assist managers and researchers to take a comprehensive approach to build an effective safety culture in ED setting.  相似文献   
67.
ABSTRACT

This study aimed to increase our understanding of processes that underlie the effect of care pathway implementation on reduced 30-day readmission rate. Adherence to evidence-based recommendations, teamwork and burnout have previously been identified as potential mechanisms in this association. We conducted a secondary data analysis of 257 patients admitted with chronic obstructive pulmonary disease exacerbation and 284 team members caring for these patients in 19 Belgian, Italian and Portuguese hospitals. Clinical measures included 30-day readmission and adherence to a specific set of five care activities. Teamwork measures included team climate for innovation, level of organized care and burnout (emotional exhaustion, level of competence and mental detachment). Care pathway implementation was significantly associated with better adherence and reduced 30-day readmission. Better adherence and higher level of competence were also related to reduced 30-day readmission. Only better adherence fully mediated the association between care pathway implementation and reduced 30-day readmission. Better team climate for innovation and level of organized care, although both improved after care pathway implementation, did not show any explanatory mechanisms in the association between care pathway implementation and reduced 30-day readmission. Implementation of a care pathway had an impact on clinical and team indicators. To reduce 30-day readmission rates, in the development and implementation of a care pathway, hospitals should measure adherence to evidence-based recommendations during the whole process, as this can give information regarding the success of implementation  相似文献   
68.
Abiotic niche lability reduces extinction risk by allowing species to adapt to changing environmental conditions in situ. In contrast, species with static niches must keep pace with the velocity of climate change as they track suitable habitat. The rate and frequency of niche lability have been studied on human timescales (months to decades) and geological timescales (millions of years), but lability on intermediate timescales (millennia) remains largely uninvestigated. Here, we quantified abiotic niche lability at 8-ka resolution across the last 700 ka of glacial–interglacial climate fluctuations, using the exceptionally well-known fossil record of planktonic foraminifera coupled with Atmosphere–Ocean Global Climate Model reconstructions of paleoclimate. We tracked foraminiferal niches through time along the univariate axis of mean annual temperature, measured both at the sea surface and at species’ depth habitats. Species’ temperature preferences were uncoupled from the global temperature regime, undermining a hypothesis of local adaptation to changing environmental conditions. Furthermore, intraspecific niches were equally similar through time, regardless of climate change magnitude on short timescales (8 ka) and across contrasts of glacial and interglacial extremes. Evolutionary trait models fitted to time series of occupied temperature values supported widespread niche stasis above randomly wandering or directional change. Ecotype explained little variation in species-level differences in niche lability after accounting for evolutionary relatedness. Together, these results suggest that warming and ocean acidification over the next hundreds to thousands of years could redistribute and reduce populations of foraminifera and other calcifying plankton, which are primary components of marine food webs and biogeochemical cycles.

Abiotic niche dynamics determine patterns of community composition over space and regulate trajectories of diversity over time (1). Both niche lability (2, 3) and conservatism (1, 4) have been proposed to spur speciation, and abiotic niche lability has been associated with ecological invasions (57) and with reduced risk of extinction during times of climate change (8). Thus, a deeper understanding of species’ propensity for niche stasis versus lability could improve predictions of biodiversity restructuring in response to anthropogenic climate change (9).Stasis in species’ abiotic niches through time has been documented in empirical research, but most such studies have been limited to ecological niche modeling on decadal scales (reviewed in ref. 10) or paleoecological examination on 106 to 107 y scales (5, 11, 12). Since empirical rates of niche change are scarce and difficult to acquire, many studies merely assume that niche evolution occurs at a constant rate along branches of a phylogeny (2, 3, 6, 7). Niche dynamics at intermediate timescales of centuries to millennia are particularly poorly documented (10), and studies at this meso scale have been restricted to terrestrial systems (e.g., refs. 1315) or to comparisons between the present day and the single historical time step of the Last Glacial Maximum, ∼21 ka (1620). Quantifying the rate and relative frequency of niche change in marine species over timescales of 102 to 105 years is important, however, because species will adapt or go extinct in response to anthropogenic ocean changes over this timescale (21).Here, we investigated climatic niche lability from the rich sedimentary archive of global planktonic foraminifera across the last 700 ka of glacial–interglacial cycles at 8-ka resolution. Planktonic foraminifera (Protista) construct “shells” (tests) of calcite, thereby sequestering carbon and recording an isotopic signature of past ocean conditions. Tests readily accumulate over large expanses of the seafloor. Consequently, the fossil record of foraminifera—arguably “the best fossil record on Earth” (22)—affords an exceptionally high-resolution view into past species distributions. This detailed record fuels studies of biostratigraphy, paleoclimatology, and paleoecology (20, 2225). Moreover, the complete species diversity of planktonic foraminifera has been described for the Plio–Pleistocene, with good agreement between morphological and molecular phylogenies (22, 2527). Although some have speculated that foraminifera competitively exclude each other (24), recent work found that planktonic foraminifera species seldom restrict each other’s distributions (28). Presumably, therefore, species occupy the full envelope of existing environmental conditions within their tolerance limits, and geographic distributions are determined almost entirely by physical ocean conditions.We developed five analyses to investigate the degree of abiotic niche lability in foraminifera. All methods examined the univariate niche axis of temperature, which is the single most important explanatory variable in regard to geographic distributions of foraminifera (20, 2932) and is a climate-related stressor and extinction driver for diverse marine fauna across timescales (33, 34). The adaptive potential of thermal niches has been taken as a key determinant of global community structure and genetic connectance in plankton (35). Primary productivity and other environmental variables, however, may also structure abiotic niches of plankton (36). Our suite of analyses quantified whether and by how much planktonic foraminiferal niches shifted along a temperature axis. First, we correlated time series of species’ thermal optima with global temperature to determine whether species tracked suitable habitat or experienced environmental fluctuations in situ. We then quantified species’ niche dissimilarity between pairs of time bins—either tracking niches across bin boundaries or contrasting niches at climatic extremes of glacial maxima and interglacial thermal peaks. To characterize niche change we applied trait evolution models to time series of temperatures at occupied sites. Lastly, we explored variation in intraspecific niche lability among ecotypes while accounting for phylogenetic relatedness. SI Appendix, Table S1 lists the response variable and sample size for each analysis.  相似文献   
69.
Abrupt transitions of regional climate in response to the gradual rise in atmospheric greenhouse gas concentrations are notoriously difficult to foresee. However, such events could be particularly challenging in view of the capacity required for society and ecosystems to adapt to them. We present, to our knowledge, the first systematic screening of the massive climate model ensemble informing the recent Intergovernmental Panel on Climate Change report, and reveal evidence of 37 forced regional abrupt changes in the ocean, sea ice, snow cover, permafrost, and terrestrial biosphere that arise after a certain global temperature increase. Eighteen out of 37 events occur for global warming levels of less than 2°, a threshold sometimes presented as a safe limit. Although most models predict one or more such events, any specific occurrence typically appears in only a few models. We find no compelling evidence for a general relation between the overall number of abrupt shifts and the level of global warming. However, we do note that abrupt changes in ocean circulation occur more often for moderate warming (less than 2°), whereas over land they occur more often for warming larger than 2°. Using a basic proportion test, however, we find that the number of abrupt shifts identified in Representative Concentration Pathway (RCP) 8.5 scenarios is significantly larger than in other scenarios of lower radiative forcing. This suggests the potential for a gradual trend of destabilization of the climate with respect to such shifts, due to increasing global mean temperature change.The gradual rise in greenhouse gas concentrations is projected to drive a mostly smooth increase in global temperature (1). However, the Earth system is suspected to have a range of “tipping elements” with the characteristic that their gradual change will be punctuated by critical transitions on regional scales (2, 3). That is, for relatively small changes in atmospheric concentrations of greenhouse gases, parts of the Earth system exhibit major changes. The recent fifth Assessment Report (AR5) of the Intergovernmental Panel on Climate Change (IPCC) presents a catalog of possible abrupt or irreversible changes (table 12.4 in ref. 4). This catalog builds on a previous literature review (2) of components believed to have the potential for an acceleration of change as fossil fuel burning changes atmospheric composition and thus radiative forcing.The expert elicitation (2) motivated discussion of a multitude of environmental threats to the planet in which it was critically argued that atmospheric carbon dioxide concentration should not cross 350 ppm (5), trying to determine what constitutes safe levels of global warming. This threshold was suggested in ref. 5 to minimize the risk due to massive sea ice change, sea level rise, or major changes to terrestrial ecosystems and crops. An alternative purely temperature-based threshold is that from the Copenhagen accord, setting an upper limit of 2° (6). However, major uncertainty exists in knowledge of climate sensitivity (7), which makes it difficult to relate this warming level to a precise CO2 concentration. However, despite this and the growing interest in the societal effects of such transitions, there has been no systematic study of the potential for abrupt shifts in state-of-the-art Earth System Models.To explore what may be deduced from the current generation of climate models in this context, we analyze the simulations produced by Coupled Model Intercomparison Project 5 (CMIP5) (8) that were used to inform the IPCC. CMIP5 provides a compilation of coordinated climate model experiments. Each of 37 analyzed models includes representations of the oceans, atmosphere, land surface, and cryosphere. The climate models have been forced with future changes in atmospheric gas concentrations, depicted in four Representative Concentration Pathways (RCPs) (9), starting in year 2006. Of these, we analyze RCP2.6, RCP4.5, and RCP8.5 to explore a range of changes in radiative forcing, reaching levels of 2.6 W⋅m−2, 4.5 W⋅m−2, and 8.5 W⋅m−2, respectively, by year 2100 (including all available simulations that go beyond 2100). We also analyze historical simulations, capturing changes from preindustrial conditions in year 1850 to the present, and preindustrial control simulations.To assess future risks of abrupt, potentially irreversible, changes in important climate phenomena, we first need to define what we mean by “abrupt.” This term clearly refers to time scale and is usually defined as when changes observed are faster than the time scale of the external forcing. Here we choose a methodology consisting of three stages. Firstly, we systematically screen the CMIP5 multimodel ensemble of simulations for evidence of abrupt changes using search criteria (Methods) to make a first filtering of regions of potentially relevant abrupt events from this dataset (stage 1). These criteria are motivated by the definition of the assessment report, AR5 (4): “A large-scale change in the climate system that takes place over a few decades or less, persists (or is anticipated to persist) for at least a few decades, and causes substantial disruptions in human and natural systems.” Other definitions have emphasized the timescales of the change, e.g., 30 y (10), and rapidity in comparison with the forcing (11), which also meet our search criteria. Global maps of quantities with potential to change abruptly are expressed as (i) the mean difference between end and beginning of a simulation, (ii) the SD of the detrended time series, and (iii) the maximum absolute change within 10 y. These maps are made for all scenario runs and compared with values for the preindustrial control runs. When at least two indicators suggest locations of major change, we construct time series for area averages of at least 0.5 × 106 km2 (roughly 10 by 10 degrees) and visually inspect these for abrupt shifts standing out from the internal variability (stage 2). Subsequently, we check whether the selected cases can indeed be considered examples of abrupt change applying formal classification criteria (Methods) such as the criterion that the change should be larger than 4 times the SD of the preindustrial simulation, in combination with additional statistical tests (stage 3).We find a broad range of transitions passing our classification criteria (Fig. 1, SI Appendix, Table S1), which can be grouped into four categories (Fig. 2). They include abrupt shifts in sea ice and ocean circulation patterns as well as abrupt shifts in vegetation and the terrestrial cryosphere. Fig. 2 shows a selected example for each category. All other time series are displayed in Fig. 3. Information on the regions where the shifts occur and the results of the statistical tests used for classification are displayed in SI Appendix, Tables S2 and S3, respectively. A list of the climate models and their acronyms is provided in SI Appendix, Table S1.Open in a separate windowFig. 1.Geographical location of the abrupt climate change occurrences. All 30 model cases listed in
CategoryTypeRegionModels and scenarios
I (switch)1. sea ice bimodalitySouthern OceanBCC-CSM1-1 (all), BCC-CSM1-1-m (all), IPSL-CM5A-LR (all), GFDL-CM3 (all)
II (forced2. sea ice bimodalitySouthern OceanGISS-E2-H (rcp45), GISS-E2-R (rcp45, rcp85)
transition to switch)3. abrupt change in productivityIndian Ocean offIPSL-CM5A-LR (rcp85)
East Africa
III (rapid change to new state)4. winter sea ice collapseArctic OceanMPI-ESM-LR (rcp85), CSIRO-MK3-6-0 (rcp85), CNRM-CM5 (rcp85), CCSM4 (rcp85), HadGEM2-ES (rcp8.5)
5. abrupt sea ice decreaseregions of high-latitude oceansCanESM2 (rcp85), CMCC-CESM (rcp85), FGOALS-G2 (rcp85), MRI-CGCM3 (all rcp)
6. abrupt increase in sea iceregion in Southern OceanMRI-CGCM3 (rcp45)
7. local collapse of convectionLabrador Sea, North AtlanticGISS-E2-R (all rcp), GFDL-ESM2G (his), CESM1-CAM (rcp85), MIROC5 (rcp26), CSIRO-MK3-6-0 (rcp26)
8. total collapse of convectionNorth AtlanticFIO-ESM (all rcp)
9. permafrost collapseArcticHADGEM2-ES (rcp85)
10. abrupt snow meltTibetan PlateauGISS-E2-H (rcp45, rcp85), GISS-E2-R (rcp45, rcp85)
11. abrupt change in vegetationEastern SahelBNU-ESM (all rcp)
IV (gradual change to new state)12. boreal forest expansionArcticHadGEM2-ES (rcp85)
13. forest diebackAmazonHadGEM2-ES (rcp85), IPSL-CM5A-LR (rcp85)
Open in a separate windowFour categories are listed by type (column 2), region (column 3), and climate model and scenario (column 4). Fig. 2 provides examples of abrupt shifts for each category.Open in a separate windowFig. 2.Examples of different categories of abrupt climate change detected in the CMIP5 database. Evolutions of (A) (category I: internally generated switches between two different states, case b in Fig. 1) regional annual mean sea ice cover in the Southern Ocean in the preindustrial control run of bcc-csm1-1-m; (B) (category II: a forced transition to switches between two different states, case f in Fig. 1) regional annual mean sea ice cover in the Southern Ocean in the historical and rcp4.5 run of GISS-E2-H; (C) (category III: singular rapid abrupt change toward a new state, case t in Fig. 1) SST in the Labrador Sea in the historical and rcp4.5 run of GFDL-ESM2G; and (D) (category IV: gradual sequence of abrupt changes toward a new state, case E in Fig. 1) tree cover in the Arctic tundra in the historical and rcp8.5 run of HadGEM2-ES.Open in a separate windowFig. 3.Time series of all abrupt events not shown in Fig 2. All cases display annual means. Type-2 sic_GISS-E2_R_rcp45 and Type-2 sic-GISS-E2-H_rcp45 are ensemble members r2i1p3; Type-4 sic_CanESM2_rcp85 is ensemble member r5i1p1; Type_10 snw_GISS-E2-R_rcp45 is ensemble member r2i1p2; Type_10 snw_GISS-E2-R_rcp85 is ensemble member r1i1p2; all other types display time series from ensemble member r1i1p1; uswr, upward shortwave radiation; mpp, marine primary production; smc, soil moisture content.  相似文献   
70.
Soils on exposed Sunda shelf shaped biogeographic patterns in the equatorial forests of Southeast Asia     
Slik JW  Aiba S  Bastian M  Brearley FQ  Cannon CH  Eichhorn KA  Fredriksson G  Kartawinata K  Laumonier Y  Mansor A  Marjokorpi A  Meijaard E  Morley RJ  Nagamasu H  Nilus R  Nurtjahya E  Payne J  Permana A  Poulsen AD  Raes N  Riswan S  van Schaik CP  Sheil D  Sidiyasa K  Suzuki E  van Valkenburg JL  Webb CO  Wich S  Yoneda T  Zakaria R  Zweifel N 《Proceedings of the National Academy of Sciences of the United States of America》2011,108(30):12343-12347
The marked biogeographic difference between western (Malay Peninsula and Sumatra) and eastern (Borneo) Sundaland is surprising given the long time that these areas have formed a single landmass. A dispersal barrier in the form of a dry savanna corridor during glacial maxima has been proposed to explain this disparity. However, the short duration of these dry savanna conditions make it an unlikely sole cause for the biogeographic pattern. An additional explanation might be related to the coarse sandy soils of central Sundaland. To test these two nonexclusive hypotheses, we performed a floristic cluster analysis based on 111 tree inventories from Peninsular Malaysia, Sumatra, and Borneo. We then identified the indicator genera for clusters that crossed the central Sundaland biogeographic boundary and those that did not cross and tested whether drought and coarse-soil tolerance of the indicator genera differed between them. We found 11 terminal floristic clusters, 10 occurring in Borneo, 5 in Sumatra, and 3 in Peninsular Malaysia. Indicator taxa of clusters that occurred across Sundaland had significantly higher coarse-soil tolerance than did those from clusters that occurred east or west of central Sundaland. For drought tolerance, no such pattern was detected. These results strongly suggest that exposed sandy sea-bed soils acted as a dispersal barrier in central Sundaland. However, we could not confirm the presence of a savanna corridor. This finding makes it clear that proposed biogeographic explanations for plant and animal distributions within Sundaland, including possible migration routes for early humans, need to be reevaluated.  相似文献   
[首页] « 上一页 [2] [3] [4] [5] [6] 7 [8] [9] [10] [11] [12] 下一页 » 末  页»
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号