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   1606818篇
  免费   131841篇
  国内免费   2598篇
耳鼻咽喉   21706篇
儿科学   53108篇
妇产科学   46330篇
基础医学   228435篇
口腔科学   47246篇
临床医学   141775篇
内科学   315635篇
皮肤病学   34154篇
神经病学   130536篇
特种医学   64832篇
外国民族医学   474篇
外科学   244346篇
综合类   39749篇
现状与发展   3篇
一般理论   546篇
预防医学   123524篇
眼科学   36519篇
药学   121584篇
  3篇
中国医学   2976篇
肿瘤学   87776篇
  2018年   14932篇
  2016年   13015篇
  2015年   15171篇
  2014年   20827篇
  2013年   31615篇
  2012年   42956篇
  2011年   45152篇
  2010年   26542篇
  2009年   25527篇
  2008年   43311篇
  2007年   45595篇
  2006年   46393篇
  2005年   45023篇
  2004年   44382篇
  2003年   42468篇
  2002年   41532篇
  2001年   75723篇
  2000年   78352篇
  1999年   66426篇
  1998年   17780篇
  1997年   16363篇
  1996年   16358篇
  1995年   16057篇
  1994年   15097篇
  1993年   14254篇
  1992年   55440篇
  1991年   53785篇
  1990年   52571篇
  1989年   50843篇
  1988年   47233篇
  1987年   46568篇
  1986年   44290篇
  1985年   42850篇
  1984年   32056篇
  1983年   27577篇
  1982年   16155篇
  1981年   14452篇
  1980年   13571篇
  1979年   30471篇
  1978年   21068篇
  1977年   17771篇
  1976年   16700篇
  1975年   17576篇
  1974年   21490篇
  1973年   20672篇
  1972年   18853篇
  1971年   17771篇
  1970年   16289篇
  1969年   15268篇
  1968年   13949篇
排序方式: 共有10000条查询结果,搜索用时 1 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