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   2876篇
  免费   139篇
  国内免费   24篇
耳鼻咽喉   34篇
儿科学   103篇
妇产科学   33篇
基础医学   308篇
口腔科学   228篇
临床医学   206篇
内科学   544篇
皮肤病学   55篇
神经病学   216篇
特种医学   340篇
外科学   319篇
综合类   53篇
预防医学   314篇
眼科学   15篇
药学   129篇
中国医学   23篇
肿瘤学   119篇
  2023年   16篇
  2022年   43篇
  2021年   70篇
  2020年   54篇
  2019年   52篇
  2018年   80篇
  2017年   48篇
  2016年   64篇
  2015年   80篇
  2014年   97篇
  2013年   148篇
  2012年   186篇
  2011年   209篇
  2010年   130篇
  2009年   128篇
  2008年   171篇
  2007年   150篇
  2006年   130篇
  2005年   107篇
  2004年   80篇
  2003年   77篇
  2002年   63篇
  2001年   42篇
  2000年   38篇
  1999年   46篇
  1998年   59篇
  1997年   62篇
  1996年   46篇
  1995年   28篇
  1994年   47篇
  1993年   29篇
  1992年   23篇
  1991年   27篇
  1990年   20篇
  1989年   39篇
  1988年   34篇
  1987年   27篇
  1986年   40篇
  1985年   27篇
  1984年   24篇
  1983年   18篇
  1982年   18篇
  1981年   27篇
  1980年   11篇
  1979年   14篇
  1978年   13篇
  1977年   17篇
  1976年   16篇
  1975年   15篇
  1970年   9篇
排序方式: 共有3039条查询结果,搜索用时 0 毫秒
1.
2.
3.
4.
As in the principal industrial countries, Brazilian women have lived longer than men. However, paradoxically, women present higher morbidity indicators than men. Knowledge of the Brazilian pattern regarding this matter could be a useful contribution to an understanding of their determinants in our specific reality, as well as enabling us to foresee future trends that would make it possible to plan adjustment in the health system. A morbidity study based on data from the National Household Sample Survey (PNAD/IBGE), was undertaken in ten Brazilian states in 1986 with this in view. Coefficients of the prevalence of perceived morbidity, demand for and utilization of health services according to sex, standardized by age and using the direct method, were built up. As a measurement of the differentials, sex ratios were calculated. The excess of perceived morbidity in women was constant in all the regions. The sex differential in the utilization of health services showed regional variations, suggesting a relationship with the health services supply. Sex differentials were not observed in childhood; the highest values were found during the woman's reproductive period, decreasing sharply after 60 years of age. The pattern is very similar in all regions. In the present study, the findings could be partially explained by the methodology adopted, but they are similar to the findings reported in other countries. The intense transformations in the reproductive pattern and in the social status of Brazilian women probably have a considerable impact on the health status and on the recourse to health services, not as yet evaluated.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
5.
Y zeolites with different sodium contents and a sodium mordenite were evaluated as support for bis(cyclopentadienyl)zirconium dichloride as catalyst for ethylene polymerization. The results showed that, although the activities of the supported catalysts were lower than that of the homogeneous system, the average molecular weight of the polyethylene produced from the former was in general much higher than that of the polymer produced in solution. Contrary to the expected trend if the specific area was the dominant factor for catalyst activity, the best catalyst was the one supported on NaM zeolite. Thus, our results indicate that the concentration of framework aluminium atoms is the dominant factor, but that the contribution of the external surface is also important.  相似文献   
6.
7.
Characteristics of the specificity and affinity of surface Fc-receptors induced on Raji (a Burkitt's lymphoma derived B cell line) and Molt-4 (a T cell line derived from a leukaemic patient) after herpes simplex virus (HSV) infection were studied, together with the expression of other surface markers. Inhibition experiments of EA-rosetting suggested that Raji cells infected by HSV had a higher affinity for soluble aggregated IgG than for IgG serologically adsorbed onto erythrocytes; an opposite pattern was noted with Molt-4, a non-Burkitt's lymphoma cell line. Using radiometric and microspectrofluorometric techniques, the expression of Fc-receptors, as detected by their capacity to fix aggregated IgG, paralleled the expression of serologically detectable Fc-receptors and Ia determinants. In contrast to beta 2-microglobulin, both Fc-receptor and Ia antigen expression increased following Hsv infection: this suggests a specific induction of these markers on human lymphoid cells following HSV infection. To our knowledge, this is the first report showing a specific induction of both Fc-receptors and Ia antigens by HSV following in vitro infection of human lymphoid cells.  相似文献   
8.
9.

Background  

The Internet has been increasingly utilized in biomedical research. From online searching for literature to data sharing, the Internet has emerged as a primary means of research for many physicians and scientists. As a result, Web-based surveys have been employed as an alternative to traditional, paper-based surveys. We describe DADOS-Survey, an open-source Web-survey application developed at our institution that, to the best of our knowledge, is the first to be compliant with the Checklist for Reporting Results of Internet E-Surveys (CHERRIES). DADOS-Survey was designed with usability as a priority, allowing investigators to design and execute their own studies with minimal technical difficulties in doing so.  相似文献   
10.
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