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   2736578篇
  免费   204033篇
  国内免费   6074篇
耳鼻咽喉   36188篇
儿科学   90529篇
妇产科学   75645篇
基础医学   387786篇
口腔科学   77702篇
临床医学   247902篇
内科学   536539篇
皮肤病学   62847篇
神经病学   217780篇
特种医学   103252篇
外国民族医学   696篇
外科学   411793篇
综合类   63974篇
现状与发展   7篇
一般理论   948篇
预防医学   209549篇
眼科学   64161篇
药学   197212篇
  7篇
中国医学   6599篇
肿瘤学   155569篇
  2021年   20820篇
  2019年   21965篇
  2018年   31535篇
  2017年   23884篇
  2016年   26606篇
  2015年   29992篇
  2014年   42069篇
  2013年   62394篇
  2012年   85533篇
  2011年   90650篇
  2010年   53443篇
  2009年   50364篇
  2008年   83812篇
  2007年   88982篇
  2006年   89793篇
  2005年   86446篇
  2004年   83154篇
  2003年   79255篇
  2002年   76396篇
  2001年   138689篇
  2000年   142183篇
  1999年   117720篇
  1998年   32343篇
  1997年   28531篇
  1996年   28602篇
  1995年   27370篇
  1994年   24978篇
  1993年   23254篇
  1992年   89733篇
  1991年   86115篇
  1990年   82872篇
  1989年   79550篇
  1988年   72814篇
  1987年   71159篇
  1986年   66658篇
  1985年   63473篇
  1984年   47401篇
  1983年   40099篇
  1982年   23380篇
  1979年   41808篇
  1978年   29106篇
  1977年   24481篇
  1976年   23042篇
  1975年   23960篇
  1974年   29006篇
  1973年   27980篇
  1972年   26059篇
  1971年   23908篇
  1970年   22537篇
  1969年   21015篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
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   
3.
4.
BackgroundThe aim of this study was to estimate the prevalence of dental prosthetic treatment and to investigate the demographic, social, economic and medical factors associated with the use of fixed and removable dentures in a representative sample of adults living in France.MethodsThe data were obtained from the 2002–2003 Decennial Health Survey, a cross-sectional study of a representative sample of the population living in France, which included 29,679 adults. Information was collected by interview. The variables collected were fixed denture, removable denture, age, gender, number of children, area of residence, nationality, educational attainment, family social status, employment status, annual household income per capita, supplementary insurance, chronic disease, eyesight problems/glasses, hearing problems/hearing aids. Multinomial logistic regression models were used to study the relationship between prosthetic treatment and demographic, socioeconomic and medical characteristics unadjusted, adjusted for age and adjusted for all the characteristics.ResultsThe prevalence of prosthetic treatment was 34.6% (95% confidence interval (CI): [34.1; 35.2]) for fixed prosthetic dentures and 13.8% (95% CI: [13.4; 14.2]) for removable prosthetic dentures. We showed a gradient between educational attainment and removable dentures; the odds ratio adjusted for all the variables (aOR) associated with no or primary education compared to post-secondary education was 2.56; 95% CI: [2.09; 3.13]. When annual household income per capita was low, subjects were less likely to report fixed dentures (aOR = 0.68; 95% CI: [0.62; 0.75]) than those with high annual household income per capita. Individuals without insurance less often reported fixed dentures than those with private insurance. Those reporting chronic disease were less likely to report fixed dentures (aOR = 0.87; 95% CI: [0.79; 0.95]) but more likely to report removable dentures (aOR = 1.29; 95% CI: [1.17; 1.43]) than those without chronic disease.ConclusionThis study reveals social, economic and medical inequalities in fixed and removable prosthetic treatment among adults in France.  相似文献   
5.
6.
7.
8.
9.
10.
Graefe's Archive for Clinical and Experimental Ophthalmology - The published online version contains mistake as the author's first name and last name have been interchanged as "Hild...  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