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   2441179篇
  免费   190249篇
  国内免费   6996篇
耳鼻咽喉   32071篇
儿科学   80530篇
妇产科学   68724篇
基础医学   352669篇
口腔科学   66783篇
临床医学   230405篇
内科学   476785篇
皮肤病学   53129篇
神经病学   202417篇
特种医学   90921篇
外国民族医学   790篇
外科学   351167篇
综合类   56268篇
现状与发展   4篇
一般理论   900篇
预防医学   202665篇
眼科学   54823篇
药学   176291篇
  7篇
中国医学   5689篇
肿瘤学   135386篇
  2021年   19343篇
  2019年   20532篇
  2018年   28772篇
  2017年   21782篇
  2016年   24263篇
  2015年   27410篇
  2014年   38394篇
  2013年   58393篇
  2012年   79728篇
  2011年   84539篇
  2010年   49453篇
  2009年   46504篇
  2008年   77786篇
  2007年   82183篇
  2006年   82799篇
  2005年   80124篇
  2004年   76265篇
  2003年   72846篇
  2002年   70265篇
  2001年   114092篇
  2000年   117209篇
  1999年   97827篇
  1998年   28059篇
  1997年   25484篇
  1996年   25285篇
  1995年   24119篇
  1994年   22196篇
  1993年   20831篇
  1992年   75827篇
  1991年   73475篇
  1990年   71185篇
  1989年   67631篇
  1988年   62556篇
  1987年   60907篇
  1986年   57466篇
  1985年   54836篇
  1984年   41637篇
  1983年   35409篇
  1982年   21580篇
  1981年   19097篇
  1979年   37528篇
  1978年   26566篇
  1977年   22034篇
  1976年   21181篇
  1975年   21708篇
  1974年   26411篇
  1973年   25773篇
  1972年   23824篇
  1971年   21989篇
  1970年   20707篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
12.
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   
13.
14.
15.
The coronavirus 2019 pandemic has affected almost every aspect of health care delivery in the United States, and the emergency medicine system has been hit particularly hard while dealing with this public health crisis. In an unprecedented time in our history, medical systems and clinicians have been asked to be creative, flexible, and innovative, all while continuing to uphold the important standards in the US health care system. To continue providing quality services to patients during this extraordinary time, care providers, organizations, administrators, and insurers have needed to alter longstanding models and procedures to respond to the dynamics of a pandemic. The Emergency Medicine Treatment and Active Labor Act of 1986, or EMTALA, is 1 example of where these alterations have allowed health care facilities and clinicians to continue their work of caring for patients while protecting both the patients and the clinicians themselves from infectious exposures at the same time.  相似文献   
16.
17.
18.
19.
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   
20.
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