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   14926篇
  免费   1158篇
  国内免费   119篇
耳鼻咽喉   173篇
儿科学   261篇
妇产科学   109篇
基础医学   1098篇
口腔科学   207篇
临床医学   1026篇
内科学   936篇
皮肤病学   394篇
神经病学   640篇
特种医学   507篇
外科学   622篇
综合类   849篇
现状与发展   1篇
预防医学   7026篇
眼科学   117篇
药学   1774篇
  3篇
中国医学   52篇
肿瘤学   408篇
  2024年   16篇
  2023年   183篇
  2022年   287篇
  2021年   500篇
  2020年   552篇
  2019年   535篇
  2018年   499篇
  2017年   532篇
  2016年   522篇
  2015年   504篇
  2014年   1023篇
  2013年   1412篇
  2012年   980篇
  2011年   1043篇
  2010年   776篇
  2009年   762篇
  2008年   750篇
  2007年   651篇
  2006年   593篇
  2005年   462篇
  2004年   407篇
  2003年   320篇
  2002年   251篇
  2001年   227篇
  2000年   237篇
  1999年   148篇
  1998年   179篇
  1997年   150篇
  1996年   188篇
  1995年   160篇
  1994年   131篇
  1993年   108篇
  1992年   152篇
  1991年   116篇
  1990年   107篇
  1989年   87篇
  1988年   84篇
  1987年   75篇
  1986年   55篇
  1985年   77篇
  1984年   78篇
  1983年   51篇
  1982年   60篇
  1981年   38篇
  1980年   36篇
  1979年   21篇
  1978年   20篇
  1977年   19篇
  1976年   16篇
  1974年   7篇
排序方式: 共有10000条查询结果,搜索用时 359 毫秒
11.
12.
The presence of pesticides in the Israeli food supply is well documented but little is known about the risks posed by children's diets for potential exposures. We investigated potential exposures to food-borne pesticides in a sample of 301 urban Israeli children (2008–10). Data from a food frequency questionnaire, 24 hour food recall, and Israel's national pesticide monitoring program were used to estimate uptake factors for 26 compounds in 27 fruits and vegetables. A pilot risk assessment was performed and the findings were compared with the Israel Ministry of Health's 2012 pesticide risk assessment for the general population. The surveyed children had higher potential exposures than the general population for over one third of the compounds, and uptake factors exceeded the Acceptable Daily Intake in ten compounds. Methamidophos, exceeded the ADI at the 25th percentile and fenamiphos, iprodione, and oxydemethon methyl, exceeded the ADI at the 50 percentile. ADIs for several compounds were exceeded even though the residues detected were below the statutory limit. Improved monitoring, enforcement, and revision of the Maximum Residue Limit for certain food/pesticide pairs are indicated as is the need to incorporate data on children's actual food consumption in national risk assessments.  相似文献   
13.
14.
Several tools to facilitate the risk assessment and management of manufactured nanomaterials (MN) have been developed. Most of them require input data on physicochemical properties, toxicity and scenario-specific exposure information. However, such data are yet not readily available, and tools that can handle data gaps in a structured way to ensure transparent risk analysis for industrial and regulatory decision making are needed. This paper proposes such a quantitative risk prioritisation tool, based on a multi-criteria decision analysis algorithm, which combines advanced exposure and dose-response modelling to calculate margins of exposure (MoE) for a number of MN in order to rank their occupational risks. We demonstrated the tool in a number of workplace exposure scenarios (ES) involving the production and handling of nanoscale titanium dioxide, zinc oxide (ZnO), silver and multi-walled carbon nanotubes. The results of this application demonstrated that bag/bin filling, manual un/loading and dumping of large amounts of dry powders led to high emissions, which resulted in high risk associated with these ES. The ZnO MN revealed considerable hazard potential in vivo, which significantly influenced the risk prioritisation results. In order to study how variations in the input data affect our results, we performed probabilistic Monte Carlo sensitivity/uncertainty analysis, which demonstrated that the performance of the proposed model is stable against changes in the exposure and hazard input variables.  相似文献   
15.
16.
Although classified by the Joint Monitoring Programme (JMP) as unimproved sanitation facilities, public toilets still play a critical role in eliminating open defecation in informal settlements. We explored perspectives of toilet operators on opportunities and barriers to operation and maintenance (O&M) of public toilets in informal settlements. A cross-sectional study design was used. Up to 20 in-depth interviews were used to obtain data on the experiences of public toilet operators. Thematic content analysis was used.

Ressults show that opportunities for improving O&M include; operation of public toilets is a source of livelihood; operators are knowledgeable on occupational risks, and the community is involvedin sanitation activities. Barriers to effective O&M include; high operation costs, failure to break even and a lack of investments in occupational health Therefore, there is need to recognise the significance of public toilets as a viable alternative to open defecation in areas where ownership of private sanitation facilities is difficult. Failure to observe the health and safety of toilet operators may further compromise O&M.  相似文献   

17.
18.
《Journal of hand therapy》2020,33(4):528-539
Study DesignProspective longitudinal cohort study.IntroductionTraumatic brachial plexus injuries (BPIs) can be devastating and negatively impact daily function and quality of life. Occupational therapists play an important role in rehabilitation; however, studies identifying outcomes are lacking.PurposeThis study aims to describe outcomes including motor recovery, upper limb function, participation, pain, and quality of life for people receiving occupational therapy intervention.MethodsA convenience sample of English-speaking adults (n = 30) with a traumatic BPI, attending the clinic between December 1, 2014, to November 30, 2016, participated. Participants received occupational therapy focusing on sensorimotor retraining and activity-based rehabilitation. Data on active range of motion (goniometry), strength (Medical Research Council (MRC)), upper-limb function (UEFI15, QuickDASH), participation (PSFS), pain (Brief Pain Inventory), and quality of life (EQ-5D-3L) were collected at baseline, 3, 6, 9, and 12 months.ResultsElbow flexion strength showed significant improvement at all time-points, average increase 2.17 (MRC) (95% confidence interval: 1.29-3.04; P < .001) and mean final MRC grading 3.86 (standard error: 0.44). Significant improvements at 12 months were seen in: shoulder abduction strength and range, flexion strength and range, external rotation range; elbow extension strength and flexion range; thumb flexion and extension strength. Upper limb function (QuickDASH) showed significant improvement (mean change = 18.85; 95% confidence interval: 4.12-33.59; P = .02). Forearm protonation range and finger flexion strength were significantly worse. Remaining outcomes did not show significant improvement.ConclusionsOccupational therapy with surgical intervention can improve strength, range, and upper limb function with people following traumatic BPI. Further investigations into impact on participation, pain, and quality of life are required.  相似文献   
19.
目的 探讨员工援助计划服务对心内科护士职业认同感、职业价值观、职业压力的影响。 方法 选择2018年1-3月我院心内科护理人员58名,为其实施员工援助计划服务,评价实施前后心内科护士的职业认同感、职业价值观、职业压力感知、职业压力反应。 结果 实施后,心内科护士工作压力源各维度评分、压力感知与压力反应各维度得分均较实施前下降(P<0.05);职业价值观各维度及职业认同感各维度评分均较实施前显著提高(P<0.001)。 结论 员工援助计划可提高心内科护士职业认同感、职业价值观,缓解其职业压力感知以及职业压力反应。  相似文献   
20.
Arsenic (As) and cadmium (Cd) have recently emerged as major health concerns owing to their strong association with diabetes mellitus (DM). We aimed to investigate the heavy metals exposure towards incidence of DM at various enzymatic and hormonal levels. Additionally, association of As and Cd with Zinc (Zn, essential metal) was also evaluated. Spot urine samples were collected to assess As, Cd and Zn through ICP-OES. Serum was analyzed by assay method for fasting blood glucose, liver and renal function biomarkers. ELISA was performed to investigate the impact of heavy metals on HbA1c, α-amylase, DPP-IV, IGF-1, leptin, GSH, MDA, SOD, HDL, FFA, TG and interleukin (IL)-6. Association of heavy metals with DM was measured by odds ratio (OR) and level of significance was assessed by Chi-squared test. Unpaired student's t-test was used to compare DM-associated risk factors in heavy metals-exposed and unexposed participants. As and Cd were detectable in 75.4% and 83% participants with mean concentration of 75.5 ppb and 54.5 ppb, respectively. For As exposure, OR in the third quartile was maximum ie 1.34 (95% CI, 0.80 to 2.23), however the result was not statistically significant (P > .05). For Cd exposure, OR in the fourth quartile was considerably high, 1.62 (95% CI, 1.00 to 2.61), with a significant probability value (P < .05). Urinary Cd was negatively associated with Zn. As and Cd exposure increases the incidence of DM in the general population. Impaired hormonal and enzymatic levels in diabetic and non-diabetic exposed participants reflect the multiple organ damage by heavy metal exposure.  相似文献   
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