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   4422篇
  免费   405篇
  国内免费   24篇
耳鼻咽喉   35篇
儿科学   129篇
妇产科学   104篇
基础医学   530篇
口腔科学   92篇
临床医学   491篇
内科学   1048篇
皮肤病学   29篇
神经病学   329篇
特种医学   269篇
外科学   376篇
综合类   177篇
一般理论   8篇
预防医学   501篇
眼科学   40篇
药学   374篇
  2篇
中国医学   8篇
肿瘤学   309篇
  2021年   74篇
  2020年   48篇
  2019年   65篇
  2018年   78篇
  2017年   42篇
  2016年   48篇
  2015年   64篇
  2014年   91篇
  2013年   142篇
  2012年   178篇
  2011年   218篇
  2010年   93篇
  2009年   106篇
  2008年   173篇
  2007年   220篇
  2006年   205篇
  2005年   209篇
  2004年   199篇
  2003年   173篇
  2002年   209篇
  2001年   148篇
  2000年   146篇
  1999年   138篇
  1998年   73篇
  1997年   73篇
  1996年   61篇
  1995年   66篇
  1994年   49篇
  1993年   44篇
  1992年   72篇
  1991年   96篇
  1990年   58篇
  1989年   109篇
  1988年   97篇
  1987年   111篇
  1986年   74篇
  1985年   95篇
  1984年   63篇
  1983年   43篇
  1982年   32篇
  1980年   29篇
  1979年   45篇
  1978年   26篇
  1977年   34篇
  1974年   29篇
  1973年   41篇
  1972年   30篇
  1971年   29篇
  1970年   27篇
  1969年   27篇
排序方式: 共有4851条查询结果,搜索用时 15 毫秒
11.
12.
13.
14.
15.
16.
Theories of agrammatism have been challenged by the discovery that agrammatic patients can make above - chance judgements of grammaticality. Chinese poses an interesting test of this phenomenon, because its grammar is so austere, with few obligatory features. An on - line grammaticality judgement task was conducted with normal and aphasic speakers of Chinese, using the small set of constructions that do permit judgements of grammaticality in this language. Broca's and Wernicke's aphasics showed similar patterns, with above - chance discrimination between grammatical and ungrammatical forms, suggesting once again that Broca's aphasics are not unique in the degree of sparing or impairment that they show in receptive grammar. However, even for young normals, false - negative rates were high. We conclude that there is some sensitivity to grammatical well - formedness in Chinese aphasics, but the effect is fragile for aphasics and probabilistic for normals, reflecting the peculiar status of grammaticality in this language.  相似文献   
17.
Although intravenous digital subtraction angiography was originally intended as a means of performing lessinvasive peripheral angiography, this less invasive approach has not proven feasible for coronary artery studies. Digital imaging has, however, proven helpful for the immediate replay, enhancement and quantification of coronary arteriography and enables the performance of regional blood flow (coronary flow reserve) analysis. Flow analysis is clinically helpful in determining the hemodynamic significance of individual coronary stenoses, which cannot always be assessed even using quantitative stenosis measurements. One method of assessing flow reserve by digital means uses parametric images to display the timing (color coded) and density (intensity coded) of the contrast bolus as it transverses the regional myocardial circulation. Analysis of baseline and hyperemic condition parametric images provides quantitative regional flow reserve information.  相似文献   
18.

Purpose

Non-Hispanic Blacks in the US have lower rates of major depression than non-Hispanic Whites, in national household samples. This has been termed a “paradox,” as Blacks suffer greater exposure to social stressors, a risk factor for depression. Subgroup analyses can inform hypotheses to explain this paradox. For example, it has been suggested that selection bias in household samples undercounts depression in Blacks; if selection is driving the paradox, Black–White differences should be most pronounced among young men with low education.

Methods

We examined Black–White differences in lifetime major depression in subgroups defined simultaneously by sex, age, and education using data from the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC) and the Collaborative Psychiatric Epidemiology Surveys (CPES).

Results

In NESARC and CPES, Blacks had lower odds than Whites of lifetime major depression in 21 and 23 subgroups, respectively, of 24. All statistically significant differences were in subgroups favoring Blacks, and lower odds in Blacks were more pronounced among those with more education.

Conclusions

These results suggest that hypotheses to explain the paradox must posit global mechanisms that pertain to all subgroups defined by sex, age, and education. Results do not lend support for the selection bias hypothesis.  相似文献   
19.
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