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   2350篇
  免费   244篇
  国内免费   183篇
耳鼻咽喉   3篇
儿科学   4篇
妇产科学   15篇
基础医学   47篇
口腔科学   18篇
临床医学   123篇
内科学   101篇
皮肤病学   36篇
神经病学   7篇
特种医学   41篇
外科学   144篇
综合类   558篇
预防医学   75篇
眼科学   17篇
药学   274篇
中国医学   1287篇
肿瘤学   27篇
  2024年   3篇
  2023年   20篇
  2022年   33篇
  2021年   57篇
  2020年   59篇
  2019年   37篇
  2018年   36篇
  2017年   77篇
  2016年   121篇
  2015年   82篇
  2014年   167篇
  2013年   151篇
  2012年   171篇
  2011年   182篇
  2010年   137篇
  2009年   114篇
  2008年   119篇
  2007年   145篇
  2006年   148篇
  2005年   127篇
  2004年   128篇
  2003年   88篇
  2002年   77篇
  2001年   91篇
  2000年   71篇
  1999年   54篇
  1998年   42篇
  1997年   64篇
  1996年   20篇
  1995年   27篇
  1994年   25篇
  1993年   20篇
  1992年   17篇
  1991年   22篇
  1990年   16篇
  1989年   13篇
  1988年   5篇
  1987年   3篇
  1986年   3篇
  1985年   3篇
  1984年   1篇
  1983年   1篇
排序方式: 共有2777条查询结果,搜索用时 23 毫秒
1.
苦寒类中药善于清热燥湿以改善机体内环境稳态,目前在临床上被广泛应用于糖尿病、肥胖、炎症、菌群失调等慢性或代谢性疾病,而这些疾病往往都伴随着机体生物钟系统的失衡。改善生物钟失衡可能是苦寒药治疗这些疾病的作用机制之一,同时,在生物钟的调控下,机体新陈代谢及内分泌等行为的节律性波动也可能影响苦寒药的药效。既往对苦寒药在临床应用上的研究大部分集中于胃肠动力及激素等基础研究上,从生物钟基因的角度鲜有见到深入的研究与阐述。因此,本文从临床常用苦寒药对生物钟基因的影响及生物钟基因对苦寒药作用的影响两个方面探讨苦寒药的应用,同时分析二者之间的关系和归纳苦寒药影响生物钟基因共同的物质基础,以期为苦寒药作用多靶点以及指导临床合理用药和中药药性物质基础研究提供参考。  相似文献   
2.
李盼  陈雨微  丁丽琴  曹世杰  张德芹  邱峰 《中草药》2019,50(22):5577-5583
辛味是中药五味学说中的重要性味之一,通常具有“发散”“行气”和“行血”的作用,且辛味中药在传统医学临床应用中占有较大比例。结合中药辛味的功效内涵及传统中医理论对消渴证的认识,阐述辛味中药与消渴证治疗之间的内在联系,总结辛味中药对“消渴三消”的治疗意义与价值。并在此基础上,对中药五味理论的现代研究趋势和发展方向进行思考,为同行研究提供参考。  相似文献   
3.
Agri-environmental schemes (AES) aim to restore biodiversity and biodiversity-mediated ecosystem services in landscapes impoverished by modern agriculture. However, a systematic, empirical evaluation of different AES types across multiple taxa and functional groups is missing. Within one orthogonal design, we studied sown flowering AES types with different temporal continuity, size, and landscape context and used calcareous grasslands as seminatural reference habitat. We measured species richness of 12 taxonomic groups (vascular plants, cicadas, orthopterans, bees, butterflies, moths, hoverflies, flower visiting beetles, parasitoid wasps, carabid beetles, staphylinid beetles, and birds) representing 5 trophic levels. A total of 54,955 specimens were identified using traditional taxonomic methods, and bulk arthropod samples were identified through DNA metabarcoding, resulting in a total of 1,077 and 2,110 taxa, respectively. Species richness of most taxonomic groups, as well as multidiversity and richness of pollinators, increased with temporal continuity of AES types. Some groups responded to size and landscape context, but multidiversity and richness of pollinators and natural enemies were not affected. AES flowering fields supported different species assemblages than calcareous grasslands, but assemblages became more similar to those in seminatural grasslands with increasing temporal continuity. Our results indicate that AES flowering fields and seminatural grasslands function synergistically. Flowering fields support biodiversity even when they are relatively small and in landscapes with few remaining seminatural habitats. We therefore recommend a network of smaller, temporally continuous AES flowering fields of different ages, combined with permanent seminatural grasslands, to maximize benefits for biodiversity conservation and ecosystem service delivery in agricultural landscapes.

Human societies are facing a worldwide loss of biodiversity with alarming declines of insect diversity in temperate agricultural landscapes (1, 2). This loss of biodiversity is jeopardizing agricultural production as important ecosystem services ensuring crop yields are directly driven by biodiversity (3). Biodiversity, however, requires suitable habitats for species to persist, forage, nest, reproduce, and hibernate (4, 5). This challenge has been recognized and agri-environmental schemes (AES) have been introduced in the European Union and other regions to reverse biodiversity declines, to restore functional diversity, and to harness the benefits of ecosystem services, like pollination and pest control, in agricultural landscapes (68).An important component of AES to fulfill these goals is the establishing of habitats that provide limiting resources, such as food and shelter for a broad range of organisms. Typically, farmers are financially compensated on a per area basis, but the effectiveness of schemes is often unclear. Thus, compensations might not direct farmers’ decisions among different AES to the ecologically most meaningful ones (7). A variety of different habitats are created as AES, ranging from hedgerows to sown flower strips or flowering fields, with the latter being widely used due to their flexible applicability and public appreciation (4). Recent assessments, however, found that overall, European AES are not fulfilling their goals (6, 9). Particularly, the value of AES for securing biodiversity is under debate (10, 11). Beneficial effects previously reported focused on single taxonomic or trophic levels or ecosystem services and varied among study designs, taxa, or services assessed (1214). Conclusive multitaxa approaches assessing potential services and disservices in one design are missing (8). Furthermore, it is unclear how different properties of AES habitats (e.g., their temporal continuity or size) and varying landscape context affect biodiversity across multiple taxonomic groups.Temporal continuity is an important factor affecting biodiversity. Higher temporal continuity increases heterogeneity within a habitat and creates niches for more species (15, 16). Temporal continuity also enables weak dispersers and higher tropic levels to colonize a habitat, with the latter being dependent on established populations of lower trophic levels (15). In AES habitats, the influence and the effects of temporal continuity have so far been neglected. Newly established flowering fields were found to be more attractive to pollinators than older flowering fields, but pollination services in adjacent fields peak 2 y after initial sowing (14, 17). Older AES habitats could potentially also benefit rare and endangered species with specific habitat requirements, if species assemblages in AES habitats change toward those in permanent species-rich seminatural grasslands with time or increased temporal continuity (18).Apart from temporal continuity, size might be an important predictor for the conservation value of AES habitats. Increasing habitat size leads to an increased species richness as it is accompanied with the establishment of larger, more stable populations and allows higher trophic levels to persist (1921). It is unclear whether biodiversity in a landscape benefits more from few large habitats or a network of many small habitats (22, 23). Relationships between size and species richness might therefore be essential for the planning and strategic placement of AES habitats.Source habitats for biodiversity are needed in agricultural landscapes to build up local populations in newly established AES habitats from regional species pools (24). Seminatural habitats embedded in agricultural landscapes have been shown to support farmland diversity (25, 26), and thus AES habitats in complex landscapes with high proportions of seminatural habitats potentially host the highest diversity.Here, we investigate the effects of AES differing in temporal continuity, size, and surrounding landscape context over several years on multiple taxonomic groups within one study design. Different types of flowering fields are commonly established by farmers as part of AES to provide additional flower resources. These fields are sown with seed mixtures adapted to local soil properties and taken from regional species pools. After a certain timespan, often varying from 1 to 10 y, flowering fields are returned to crop production. The studied flowering fields differed in temporal continuity from: 1) Newly sown on arable land, over 2) refreshed (i.e., flower fields resown after 5 y) to 3) continuous, 6-y-old flowering fields. Species-rich calcareous grasslands were used as permanent control (Fig. 1 and Table 1). Calcareous grasslands are seminatural biodiversity hotspots in Europe and are preserved by low intensive mowing or grazing (27). We investigated species richness in these 4 AES types across 12 taxonomic groups belonging to 5 trophic levels, including pollinators (bees, butterflies, moths, flower visiting beetles, and hoverflies) and natural enemies (parasitoid wasps, carabid beetles, staphylinid beetles, and birds) as providers of important ecosystem services (3). Species were identified by classic taxonomic techniques (vascular plants, orthopterans, bees, butterflies, moths, flower visiting beetles, carabid beetles, staphylinid beetles, and birds) and DNA metabarcoding (cicadas, hoverflies, and parasitoid wasps). Repeated recordings of a subset of four taxonomic groups (plants, orthopterans, bees, and carabid beetles) within 2 y were performed to clarify whether short-term succession changed assemblages in newly established flowering fields toward those in seminatural calcareous grasslands. Apart from analyses for each taxonomic group, we performed a multidiversity analysis by calculating a diversity index across all taxa, pollinators, and natural enemies (28). Our study aims to judge which types of AES fulfill the goal of restoring biodiversity and ecosystem services in agricultural landscapes best, and should therefore be fostered. Such data are urgently needed to build the scientific basis for a successful transition of European Union and global policies to biodiversity-friendly and sustainable crop production.Open in a separate windowFig. 1.Study design on the landscape and site level. Biodiversity across 12 different taxonomic levels (from top to bottom: Vascular plants, orthopterans, cicadas, bees, butterflies, moths, flower visiting beetles, hoverflies, parasitoid wasps, carabid beetles, staphylinid beetles, birds) was recorded using a variety of classic methods (pan traps, pitfall traps, transect walks, light traps combined with taxonomic identification) as well as metabarcoding analyses (using samples collected with Malaise traps). The different types of flowering fields and calcareous grasslands were located along a gradient of temporal continuity (Table 1). All AES types covered independent gradients of seminatural habitat in the surrounding landscape and habitat size (purple, AES; yellow, arable land; light green, seminatural habitat; dark green, forest; gray, urban). Repeated recordings over 2 y were performed for vascular plants, orthopterans, bees, and carabid beetles to assess whether succession shifted assemblages in flowering fields toward those in seminatural calcareous grasslands.Table 1.Differences in temporal continuity
Habitat age, yLast soil disturbance, yTemporal continuityPrevious land useManagementVegetation
New sown flowering field11LowArable landNoneCustomary flower seed mixture; sown in the previous year
Refreshed sown flowering field>61Low–intermediateSown flowering field (5 y)NoneCustomary flower seed mixture; sown in the previous year
Continuous sown flowering field>6>6Intermediate–highSown flowering field (5 y)Mulching above ground once per year after JuneCustomary flower seed mixture sown >6 y ago; strongly shaped by succession
Calcareous grassland>>20>>20HighNAGrazing or mowing once per year after JuneSeminatural xerothermic grassland vegetation
Open in a separate windowDifferences in temporal continuity—resulting from habitat age and management—of the studied AES types in 2016 (first year of the study).We expected that: 1) Benefits of temporal habitat continuity differ among taxonomic groups, pollinators, and natural enemies; 2) temporal continuity and short-term succession alter species assemblages of sown flowering fields toward those in seminatural grasslands; and 3) multidiversity in sown flowering fields benefits most from the combination of temporal continuity, large habitat size, and high proportion of seminatural habitats in the landscape.  相似文献   
4.
5.
气味理论是中药药性理论的核心内容。五味中之辛味能兼通四气,复兼四味。历代医籍有关气味配伍的记载有很多。如辛行淡渗、辛甘化阳、辛散咸软、辛散酸收、辛开苦降等配伍方法,充分体现了辛味药物在方剂配伍应用中的广泛性特点。因此,认真研究、总结辛味药在方剂中的作用并进而探讨其配伍规律,具有重要的理论意义和应用价值。本文以辛味药为例,探讨其在方剂学中的作用,发现:辛味药的作用主要体现在"运动"二字。这与中医学对机体的认识的主旨思想"阴阳相贯,如环无端"相一致。作用机理在于:以其"动"的特性,协其他药性之偏以纠正机体阴阳之偏,即以偏纠偏。  相似文献   
6.
目的研究表没食子儿茶素没食子酸酯(EGCG)对高盐引起的高血压模型大鼠的降压作用及作用机制。方法大鼠随机分为对照组、模型组和EGCG 50、100 mg/kg组,测定大鼠的大鼠平均动脉压,并采用Western blotting印迹法检测大鼠下丘脑室旁核(PVN)中Toll样受体4(TLR4)、核因子κB(NF-κB)p65、白细胞介素-1β(IL-1β)的水平;采用酶联免疫吸附试验(ELISA)法检测大鼠PVN中单核细胞趋化蛋白1(MCP-1)、肿瘤坏死因子α(TNF-α)和IL-6水平。结果高盐诱导的高血压模型大鼠中TLR4表达量明显增加(P<0.05)。EGCG 50、100 mg/kg显著降低大鼠的平均动脉压(P<0.05),并明显降低PVN中TLR4、NF-κBp65、IL-1β和TNF-α、IL-6、IL-1β水平(P<0.05)。结论 EGCG可降低高盐诱导大鼠的高血压,其机制可能与阻断TLR4信号有关。  相似文献   
7.
危立飞  于慧  王新陆 《天津中医药》2019,36(12):1145-1148
文章总结了前期有关血浊理论的成果,提出血浊理论是应现代疾病谱系变化而提出的新的"中医理论",用血浊理论指导中医临床可以纳入检验医学等更多的现代诊疗手段,扩展中医四诊范畴,配合"援药理论",初步形成了适应现代临床的"理法方药"系统,为指导治未病提供了良好的时代落脚点,为中医现代化提供了良好的理论典范和启示。  相似文献   
8.
Dolichandrone serrulata flower (DSF) has been believed to reduce blood glucose in hyperglycaemic persons with sub-fertility but its effect on improvement of male reproductive impairment has never been elucidated scientifically. This study attempted to investigate the hypoglycaemic effects of DSF on male reproductive damages in type 2 diabetes mellitus (T2DM) rats. Adult Sprague Dawley rats were divided into four groups (control, T2DM, DSF200 + T2DM and DSF600 + T2DM; n = 10/each). Control rats received low-fat diet for 14 days before saline injection while streptozocin (50 mg/kg BW) induced T2DM groups received high-fat diet and were orally administered with DSF (200 and 600 mg/kg BW) for 28 days. At the end, fasted blood glucose (FBG), malondialdehyde (MDA), testosterone, sperm quality, histology and protein expressions were examined. The result showed that DSF decreased high FBG and testicular MDA and increased testosterone levels of T2DM-treated rats. Low-sperm quality and histological malfunction were ameliorated in DSF-treated group. There was significant decrease in the expression of androgen receptor, heat-shock 70 and steroidogenic acute regulatory proteins of T2DM-treated rats. Our study demonstrated changes of six bands (116, 51, 45, 39, 35 and 29 kDas) of tyrosine-phosphorylated proteins. In conclusion, DSF could reduce the FBGand ameliorate the reproductive damages in male T2DM rats.  相似文献   
9.
目的探究糖尿病周围神经病变患者开展中药穴位敷贴联合中药汤剂治疗的效果。方法研究时限为2017年8月—2018年11月,研究对象为此期间收治的糖尿病周围神经病变患者42例,将其随机分为常规组(21例)、中药组(21例),分别开展常规治疗、中药穴位敷贴+中药汤剂治疗,比较治疗结果。结果2组患者治疗前中医证候积分、TCSS(多伦多临床评分)相近(P>0.05),治疗后中药组患者以上评分均较常规组具鲜明优势(P<0.05);常规组患者不良反应发生率为14.3%,与中药组0.0%相比,未见鲜明差异(P>0.05)。结论予糖尿病周围神经病变患者开展中药穴位敷贴联合中药汤剂治疗,效果安全有效。  相似文献   
10.
目的系统评价中药联合溴隐亭治疗女性高泌乳素血症的疗效和安全性。方法检索VIP、WANFANG Data,CNKI. ,PubMe[J]. Sinomed Web of Science .Embase ,Coechrane Libranry SeneDiret数据库自建库以来至2020年11月5日公开发表的与中药联合溴隐亭治疗高泌乳素血症有关的临床随机对照试验。由两名研究者根据纳人及排除标准筛选文献,运用Cochnne协作网提供的RerMan 5.4版软件进行临床疗效和安全性评价。结果共纳人18箱文献,共计1934例惠者ometa分析结果显示,与对照組相比,试验组总有效率高(P<0.01),治疗后试验组血清泌乳素(PRL)水平、中医症状积分降低,血清雄二醇(E)水 平显著升高,试验组不良反应发生率和复发率低(P<0.01)。结论联合应用中药和澳隐亭治疗女性高铭乳素血症可提高临床疗效,降低PRL水平,改善Ea水平,且更加安全。  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