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   40050篇
  免费   3158篇
  国内免费   88篇
耳鼻咽喉   299篇
儿科学   1753篇
妇产科学   1234篇
基础医学   5394篇
口腔科学   475篇
临床医学   4831篇
内科学   7327篇
皮肤病学   695篇
神经病学   4725篇
特种医学   760篇
外国民族医学   1篇
外科学   3951篇
综合类   376篇
现状与发展   1篇
一般理论   74篇
预防医学   5425篇
眼科学   641篇
药学   2620篇
中国医学   41篇
肿瘤学   2673篇
  2024年   81篇
  2023年   632篇
  2022年   1004篇
  2021年   1981篇
  2020年   1183篇
  2019年   1709篇
  2018年   1918篇
  2017年   1298篇
  2016年   1468篇
  2015年   1533篇
  2014年   2013篇
  2013年   2550篇
  2012年   3646篇
  2011年   3545篇
  2010年   1770篇
  2009年   1523篇
  2008年   2364篇
  2007年   2457篇
  2006年   2083篇
  2005年   1910篇
  2004年   1651篇
  2003年   1350篇
  2002年   1246篇
  2001年   225篇
  2000年   163篇
  1999年   227篇
  1998年   250篇
  1997年   152篇
  1996年   128篇
  1995年   127篇
  1994年   114篇
  1993年   114篇
  1992年   94篇
  1991年   74篇
  1990年   74篇
  1989年   65篇
  1988年   51篇
  1987年   40篇
  1986年   48篇
  1985年   53篇
  1984年   43篇
  1983年   33篇
  1982年   29篇
  1981年   28篇
  1980年   31篇
  1979年   22篇
  1978年   27篇
  1977年   19篇
  1974年   15篇
  1972年   20篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
Semen samples from 279 infertility patients attending an Immunological Centre were analysed to evaluate the relationship between the populations of leucocytes, seminal quality, antisperm antibodies, and seminal vesicle function. The most frequent finding between leucocytospermic samples was asthenozoospermia (57%), whereas in non-leucocytospermic samples normozoospermia was the most frequent finding (47%). In the samples with asthenozoospermia, granulocytes predominated, whereas in those with oligozoospermia and azoospermia a reduction in the number of macrophages and lymphocytes was observed, suggesting an obstructive process at the level of epididymis and/or vas deferens where these leucocytes are mostly produced. In the case of hypofunction of the seminal vesicles there was a predominance in granulocytes. The increased levels of each type of leucocytes affected seminal quality only when seminal vesicles were affected. Only the elevated granulocytes count was related to a decrease in sperm motility. In those samples with leucocytospermia, positive antisperm antibodies (ASA) were associated with low sperm motility, low sperm normal morphology, and low value of seminal corrected fructose, whereas, in the absence of leucocytospermia, ASA, were more related to low sperm counts. These data suggest that granulocytes were more related to seminal vesicles dysfunction and sperm motility changes, and that ASA may be observed in the presence or absence of leucocytospermia.  相似文献   
72.
73.
74.
75.
76.
Objective   To profile the expression of all known members of the matrix metalloproteinase ( MMP ), a disintegrin and metalloproteinase with thrombospondin motifs ( ADAMTS ), and tissue inhibitor of metalloproteinases ( TIMP s) gene families in normal cartilage and that from patients with osteoarthritis (OA).
Methods   Human cartilage was obtained from femoral heads at joint replacement for either osteoarthritis or following fracture to the neck of femur. Total RNA was purified and expression of genes assayed using quantitative real-time PCR.
Results   Several members of the above gene families were regulated in OA. Genes increasing in expression in OA were: at P  < 0.001, MMP-13 , MMP-28 , ADAMTS-16 ; at P  < 0.01, MMP-9 , MMP-16 , ADAMTS-2 , ADAMTS-14 and at P  < 0.05, MMP-2 , TIMP-3 , ADAMTS-12 . Genes decreasing in expression in OA were: at P  < 0.001, MMP-1 , MMP-3 , ADAMTS-1 ; at P  < 0.01, MMP-10 , TIMP-1 , ADAMTS-9 and at P  < 0.05, TIMP-4 , ADAMTS-5 , ADAMTS-15 . Correlation analysis revealed that groups of genes across the gene families are co-expressed in cartilage.
Conclusion   This is the first comprehensive expression profile of all known MMP , ADAMTS and TIMP genes in cartilage. Patterns of expression provide a foundation on which to understand mechanisms of gene regulation in OA and potentially for refining the specificity of anti-proteolytic therapies.  相似文献   
77.
This paper reviews the literature on colorectal cancer from a sex and gender-based perspective. Colorectal cancer is a major cause of death in the developed world, with rates increasing in developing countries. Although described by some writers as an ‘equal opportunity’ disease, it presents more risk to men than women. Both biological, or sex-linked factors, and gender-linked factors play a part in the aetiology of the disease, while gender differences in the use of screening and treatment also help shape the mortality gap between women and men for this condition. Without an appreciation of the part played by sex and gender in the risk of colorectal cancer, and without a gender-sensitive approach to screening in particular, it is possible that the mortality gap between men and women for this condition will widen in the future.  相似文献   
78.
OBJECTIVES: The impact of preoperative endoscopic therapy on the difficulty of laparoscopic Heller myotomy and the impact of the difficulty of the myotomy on long-term outcome has not been determined. This study was undertaken to determine whether preoperative therapy impacts the difficulty of laparoscopic Heller myotomy and whether preoperative therapy or difficulty of myotomy impacts long-term outcomes. METHODS: Since 1992, 305 patients, 56% male, median age 49 years, underwent laparoscopic Heller myotomy and were prospectively followed. The difficulty of the laparoscopic Heller myotomy was scored by the operating surgeon for the most recent 170 consecutive patients on a scale of 1 (easiest) to 5 (most difficult). Patients scored their symptoms before and after myotomy using a Likert scale from 0 (never/not bothersome) to 10 (always/very bothersome). RESULTS: Before myotomy, 66% of patients underwent endoscopic therapy: 33% dilation, 11% Botox, and 22% both. Preoperative endoscopic therapy did not correlate with the difficulty of the myotomy (P=NS). Median follow-up was 25 months. Regardless of the difficulty of the myotomy, dysphagia improved with myotomy (P<0.0001). By regression analysis, the frequency and severity of post-myotomy dysphagia correlated with neither preoperative endoscopic therapy nor the difficulty of the myotomy. CONCLUSIONS: Laparoscopic Heller myotomy improves the frequency and severity of dysphagia. The difficulty of laparoscopic Heller myotomy is not impacted by preoperative therapy, and neither preoperative therapy nor difficulty of the myotomy impact long-term outcome.  相似文献   
79.
80.
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