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   2826261篇
  免费   210362篇
  国内免费   6160篇
耳鼻咽喉   37025篇
儿科学   94479篇
妇产科学   77170篇
基础医学   398826篇
口腔科学   78822篇
临床医学   254071篇
内科学   554749篇
皮肤病学   63878篇
神经病学   226454篇
特种医学   107143篇
外国民族医学   696篇
外科学   427877篇
综合类   65387篇
现状与发展   7篇
一般理论   958篇
预防医学   216966篇
眼科学   65840篇
药学   203604篇
  7篇
中国医学   6845篇
肿瘤学   161979篇
  2021年   22049篇
  2019年   22718篇
  2018年   40592篇
  2017年   31032篇
  2016年   35112篇
  2015年   31198篇
  2014年   43731篇
  2013年   64180篇
  2012年   89951篇
  2011年   100128篇
  2010年   60637篇
  2009年   55597篇
  2008年   92536篇
  2007年   99477篇
  2006年   91186篇
  2005年   89128篇
  2004年   86080篇
  2003年   82851篇
  2002年   78975篇
  2001年   139202篇
  2000年   142845篇
  1999年   118072篇
  1998年   32649篇
  1997年   28847篇
  1996年   28840篇
  1995年   27601篇
  1994年   25197篇
  1993年   23433篇
  1992年   89955篇
  1991年   86351篇
  1990年   83105篇
  1989年   79752篇
  1988年   73017篇
  1987年   71356篇
  1986年   66842篇
  1985年   63641篇
  1984年   47536篇
  1983年   40203篇
  1982年   23489篇
  1979年   41937篇
  1978年   29191篇
  1977年   24529篇
  1976年   23138篇
  1975年   23986篇
  1974年   29055篇
  1973年   28017篇
  1972年   26080篇
  1971年   23939篇
  1970年   22579篇
  1969年   21061篇
排序方式: 共有10000条查询结果,搜索用时 421 毫秒
11.
The coronavirus disease 2019 (COVID-19) pandemic has rapidly created widespread impacts on global health and the economy. Data suggest that women are less susceptible to severe illness. However, sex-disaggregated data are incomplete, leaving room for misinterpretation, and focusing only on biologic sex underestimates the gendered impact of the pandemic on women. This narrative review summarizes what is known about gender disparities during the COVID-19 pandemic and the economic, domestic, and health burdens along with overlapping vulnerabilities related to the pandemic. In addition, this review outlines recommended strategies that advocacy groups, community leaders, and policymakers should implement to mitigate the widening gender disparities related to COVID-19.  相似文献   
12.
13.
14.
15.
Amacrine cells of the retina are conspicuously variable in their morphologies, their population demographics, and their ensuing functions. Vesicular glutamate transporter 3 (VGluT3) amacrine cells are a recently characterized type of amacrine cell exhibiting local dendritic autonomy. The present analysis has examined three features of this VGluT3 population, including their density, local distribution, and dendritic spread, to discern the extent to which these are interrelated, using male and female mice. We first demonstrate that Bax-mediated cell death transforms the mosaic of VGluT3 cells from a random distribution into a regular mosaic. We subsequently examine the relationship between cell density and mosaic regularity across recombinant inbred strains of mice, finding that, although both traits vary across the strains, they exhibit minimal covariation. Other genetic determinants must therefore contribute independently to final cell number and to mosaic order. Using a conditional KO approach, we further demonstrate that Bax acts via the bipolar cell population, rather than cell-intrinsically, to control VGluT3 cell number. Finally, we consider the relationship between the dendritic arbors of single VGluT3 cells and the distribution of their homotypic neighbors. Dendritic field area was found to be independent of Voronoi domain area, while dendritic coverage of single cells was not conserved, simply increasing with the size of the dendritic field. Bax-KO retinas exhibited a threefold increase in dendritic coverage. Each cell, however, contributed less dendrites at each depth within the plexus, intermingling their processes with those of neighboring cells to approximate a constant volumetric density, yielding a uniformity in process coverage across the population.SIGNIFICANCE STATEMENT Different types of retinal neuron spread their processes across the surface of the retina to achieve a degree of dendritic coverage that is characteristic of each type. Many of these types achieve a constant coverage by varying their dendritic field area inversely with the local density of like-type neighbors. Here we report a population of retinal amacrine cells that do not develop dendritic arbors in relation to the spatial positioning of such homotypic neighbors; rather, this cell type modulates the extent of its dendritic branching when faced with a variable number of overlapping dendritic fields to approximate a uniformity in dendritic density across the retina.  相似文献   
16.
17.
18.
19.
20.
Major depressive disorder and other neuropsychiatric disorders are often managed with long-term use of antidepressant medication. Fluoxetine, an SSRI antidepressant, is widely used as a first-line treatment for neuropsychiatric disorders. However, fluoxetine has also been shown to increase the risk of metabolic diseases such as non-alcoholic fatty liver disease. Fluoxetine has been shown to increase hepatic lipid accumulation in vivo and in vitro. In addition, fluoxetine has been shown to alter the production of prostaglandins which have also been implicated in the development of non-alcoholic fatty liver disease. The goal of this study was to assess the effect of fluoxetine exposure on the prostaglandin biosynthetic pathway and lipid accumulation in a hepatic cell line (H4-II-E-C3 cells). Fluoxetine treatment increased mRNA expression of prostaglandin biosynthetic enzymes (Ptgs1, Ptgs2, and Ptgds), PPAR gamma (Pparg), and PPAR gamma downstream targets involved in fatty acid uptake (Cd36, Fatp2, and Fatp5) as well as production of 15-deoxy-Δ12,14PGJ2 a PPAR gamma ligand. The effects of fluoxetine to induce lipid accumulation were attenuated with a PTGS1 specific inhibitor (SC-560), whereas inhibition of PTGS2 had no effect. Moreover, SC-560 attenuated 15-deoxy-Δ12,14PGJ2 production and expression of PPAR gamma downstream target genes. Taken together these results suggest that fluoxetine-induced lipid abnormalities appear to be mediated via PTGS1 and its downstream product 15d-PGJ2 and suggest a novel therapeutic target to prevent some of the adverse effects of fluoxetine treatment.  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