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   1601957篇
  免费   131505篇
  国内免费   2583篇
耳鼻咽喉   21646篇
儿科学   52934篇
妇产科学   46235篇
基础医学   227812篇
口腔科学   47203篇
临床医学   140917篇
内科学   314831篇
皮肤病学   34091篇
神经病学   130118篇
特种医学   64733篇
外国民族医学   474篇
外科学   243865篇
综合类   39714篇
现状与发展   3篇
一般理论   544篇
预防医学   122884篇
眼科学   36504篇
药学   121265篇
  3篇
中国医学   2974篇
肿瘤学   87295篇
  2018年   14775篇
  2016年   12902篇
  2015年   15025篇
  2014年   20650篇
  2013年   31356篇
  2012年   42564篇
  2011年   44764篇
  2010年   26346篇
  2009年   25308篇
  2008年   43002篇
  2007年   45246篇
  2006年   46055篇
  2005年   44678篇
  2004年   44099篇
  2003年   42183篇
  2002年   41296篇
  2001年   75684篇
  2000年   78329篇
  1999年   66388篇
  1998年   17732篇
  1997年   16338篇
  1996年   16314篇
  1995年   16023篇
  1994年   15071篇
  1993年   14218篇
  1992年   55430篇
  1991年   53776篇
  1990年   52566篇
  1989年   50843篇
  1988年   47225篇
  1987年   46562篇
  1986年   44287篇
  1985年   42846篇
  1984年   32035篇
  1983年   27566篇
  1982年   16149篇
  1981年   14441篇
  1980年   13570篇
  1979年   30464篇
  1978年   21068篇
  1977年   17766篇
  1976年   16696篇
  1975年   17578篇
  1974年   21489篇
  1973年   20674篇
  1972年   18855篇
  1971年   17774篇
  1970年   16292篇
  1969年   15268篇
  1968年   13951篇
排序方式: 共有10000条查询结果,搜索用时 0 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