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   1603606篇
  免费   131545篇
  国内免费   2582篇
耳鼻咽喉   21665篇
儿科学   52980篇
妇产科学   46314篇
基础医学   228163篇
口腔科学   47214篇
临床医学   140987篇
内科学   315133篇
皮肤病学   34113篇
神经病学   130269篇
特种医学   64826篇
外国民族医学   474篇
外科学   243977篇
综合类   39717篇
现状与发展   3篇
一般理论   544篇
预防医学   122971篇
眼科学   36502篇
药学   121510篇
  3篇
中国医学   2981篇
肿瘤学   87387篇
  2018年   14782篇
  2016年   12920篇
  2015年   15051篇
  2014年   20677篇
  2013年   31403篇
  2012年   42628篇
  2011年   44845篇
  2010年   26377篇
  2009年   25334篇
  2008年   43075篇
  2007年   45348篇
  2006年   46153篇
  2005年   44744篇
  2004年   44173篇
  2003年   42247篇
  2002年   41384篇
  2001年   75730篇
  2000年   78382篇
  1999年   66430篇
  1998年   17736篇
  1997年   16346篇
  1996年   16321篇
  1995年   16022篇
  1994年   15075篇
  1993年   14226篇
  1992年   55447篇
  1991年   53799篇
  1990年   52596篇
  1989年   50872篇
  1988年   47254篇
  1987年   46587篇
  1986年   44311篇
  1985年   42875篇
  1984年   32059篇
  1983年   27584篇
  1982年   16156篇
  1981年   14450篇
  1980年   13571篇
  1979年   30495篇
  1978年   21083篇
  1977年   17787篇
  1976年   16707篇
  1975年   17602篇
  1974年   21515篇
  1973年   20704篇
  1972年   18877篇
  1971年   17805篇
  1970年   16314篇
  1969年   15297篇
  1968年   13976篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
91.
92.
93.
94.
95.
A 19-item survey instrument was designed and mailed by the Infectious Diseases Society of America to its membership to determine the media preferred by infectious diseases physicians for continuing medical education on general topics and on antimicrobial resistance. The objective of the survey was to offer the developers of educational programs knowledge on which to base more-effective ways to deliver educational materials to physicians in this specialty.  相似文献   
96.
OBJECTIVE: To assess the effects of adding combined estradiol/norethisterone acetate therapy (CENT) to goserelin acetate treatment (GA) of dysfunctional uterine bleeding (DUB) in perimenopausal women. METHODS: In a randomized, placebo-controlled, double-blind trial followed by an open follow-up study, 31 perimenopausal women with DUB were recruited from gynecological outpatient departments of two Dutch hospitals and randomized for treatment with either GA/placebo or GA/CENT for 6 months followed by 18 months of GA/CENT for all. The main outcome measures were abdominal pain, number of bleeding days, double-layer endometrial thickness (DET), Greene climacteric score (GCS), visual analog scale for well-being, bone mineral density (BMD) and mammographic density (BI-RAD score). RESULTS: Abdominal pain, number of bleeding days and DET decreased in both groups, the between-group difference in decrease not being statistically significant. GCS initially showed significant improvement in the GA/CENT group. BMD decreased significantly in the GA/placebo group (-4.1%) compared with the GA/CENT group (-0.3%). Another 18 months of GA/CENT did not result in a lasting difference in BMD between groups. BI-RAD scores did not differ significantly between or within the two groups. CONCLUSIONS: Adding CENT to GA treatment for DUB in perimenopausal women initially prevented BMD loss and improved climacteric complaints, while having no negative impact on vaginal bleeding, abdominal pain or BI-RAD scores. However, prolonged treatment did not result in a lasting prevention of bone loss.  相似文献   
97.
The incidence of uterine cervical cancer has increased slightly in Western countries, with an increase in relatively young women. Overexpression of matrix metalloproteinases (MMPs)-2 and -9 has turned out as a prognostic factor in many cancers. We compared the expression of the proteins MMP-2 and MMP-9 in cervical primary tumors with clinical outcome and risk factors of cervical cancer. One hundred sixty-one patients with cervical cancer treated in Ume? University Hospital or Sahlgrenska University Hospital, Sweden, between 1991 and 1995 were included in the study. Paraffin-embedded tissue samples obtained prior to treatment were examined immunohistochemically by specific antibodies for MMP-2 and MMP-9. Forty-two percent of the tumors were intensively positive for MMP-2 and 31% for MMP-9. Nineteen percent of the samples were intensively positive for both proteinases and 47% negative or weak for both. Overexpression of MMP-2 seemed to predict unfavorable survival under Kaplan-Meier analysis and in the multivariate analysis. Early sexual activity and low parity seemed to correlate to overexpression of MMP-2. MMP-9 was not associated with survival or sexual behavior. Intensive MMP-9 was noted in grade 1 tumors. We conclude that MMP-2 and MMP-9 have different roles in uterine cervical cancer. MMP-2 could be associated with aggressive behavior, but MMP-9 expression diminishes in high-grade tumors.  相似文献   
98.
99.
100.
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