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   1607476篇
  免费   132065篇
  国内免费   2583篇
耳鼻咽喉   21691篇
儿科学   53020篇
妇产科学   46341篇
基础医学   228603篇
口腔科学   47358篇
临床医学   141636篇
内科学   315952篇
皮肤病学   34134篇
神经病学   130761篇
特种医学   64984篇
外国民族医学   474篇
外科学   244476篇
综合类   39846篇
现状与发展   3篇
一般理论   546篇
预防医学   123467篇
眼科学   36687篇
药学   121594篇
  3篇
中国医学   2979篇
肿瘤学   87569篇
  2018年   14865篇
  2016年   12981篇
  2015年   15122篇
  2014年   20791篇
  2013年   31553篇
  2012年   42894篇
  2011年   45063篇
  2010年   26515篇
  2009年   25459篇
  2008年   43283篇
  2007年   45499篇
  2006年   46310篇
  2005年   44909篇
  2004年   44325篇
  2003年   42384篇
  2002年   41537篇
  2001年   75821篇
  2000年   78455篇
  1999年   66513篇
  1998年   17808篇
  1997年   16389篇
  1996年   16379篇
  1995年   16073篇
  1994年   15121篇
  1993年   14259篇
  1992年   55566篇
  1991年   53890篇
  1990年   52665篇
  1989年   50947篇
  1988年   47328篇
  1987年   46660篇
  1986年   44370篇
  1985年   42942篇
  1984年   32114篇
  1983年   27648篇
  1982年   16193篇
  1981年   14484篇
  1980年   13602篇
  1979年   30518篇
  1978年   21118篇
  1977年   17816篇
  1976年   16734篇
  1975年   17627篇
  1974年   21543篇
  1973年   20730篇
  1972年   18901篇
  1971年   17801篇
  1970年   16339篇
  1969年   15295篇
  1968年   13973篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
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   
82.
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   
83.
84.
85.
86.
OBJECTIVES: To identify and describe current women's thoughts about the menopause, hormone treatment (HT) and perceptions about breast cancer. METHODS: Between December 2004 and January 2005, 4201 postmenopausal women in seven European countries were interviewed via a standardized computer-aided telephone interview protocol. RESULTS: Almost all women reported to have experienced climacteric symptoms, and 63% of the women rated them as being severe. Only 52% of women were aware of the benefits of HT for relief of climacteric symptoms. Although 84% felt that severe symptoms should be treated, only 40% had used HT at some point in time. Thirty-four percent of the women preferring treatment with natural products did so because of the risk of breast cancer associated with HT. HT was recognized by 59% of the women as one of the most important contributors to an increased breast cancer risk. Most women received their information about HT and breast cancer risk from the media. CONCLUSIONS: This European survey reveals that the majority of women experience climacteric symptoms but that their decision whether or not to use HT is highly dependent on their concern about breast cancer risk. An increase in knowledge of the benefits and risks of HT is required for women to make appropriate decisions about hormone use.  相似文献   
87.
Bleeding disorders encountered during administration of hormone replacement therapy (HRT) are reviewed. The incidence of bleeding disorders is dependent on the phase of HRT and the age of the patient. In the diagnosis of these bleedings transvaginal sonography and minihysteroscopy are very important methods. Endometrial thickness can be monitored exactly by transvaginal sonography. Outpatient minihysteroscopy without anesthesia results in higher compliance to HRT after the procedure. In hormonal treatment of bleeding disorders during HRT, the sonographically supported progestogen test is very useful and can reduce endometrium thickness. Operative treatments include myoma and polyp resection as well as endometrial ablation. By these methods a high rate of bleeding-free HRT can be reached. The problem of endometrial cancer during HRT is discussed on the basis of new literature and critical statements. The review shows the importance of individual diagnostic and treatment schedules for bleeding disorders during HRT.  相似文献   
88.
89.
In einer clusteranalytischen Untersuchung mit 137 Patienten, die einen Parasuizid verübt hatten, wurden 6 Subgruppen unter Berücksichtigung der Klassifikationsvariable “suicide intent” isoliert. Es wurde die Hypothese geprüft, dass sich sowohl die Motivstrukturen als auch die Raten an wiederholten Parasuiziden in Abh?ngigkeit der Clusterl?sung bedeutsam voneinander unterscheiden. Die Ergebnisse unterstützen die Annahme einer zunehmenden Ausdifferenzierung der interpersonell orientierten Motivstrukturen mit sinkendem bzw. einer Einengung der Motivstruktur auf den Todeswunsch mit steigendem “suicide intent”. Es wurden folgende Subgruppen differenziert: eine Suizid-Hochrisikogruppe mit ausschlie?licher Todesintention und -motivation, 2 moderate Suizid-Risikogruppen mit hoher Todesintention und leichten Tendenzen zu interpersoneller Motivation, eine Subgruppe, gekennzeichnet durch eine manipulativ/strategisch orientierte Motivstruktur und auff?llig h?ufigen Parasuizidwiederholungen, eine Subgruppe mit vorrangig appellativ orientierten Motiven, Kontrollverlust und vergleichsweise seltenen Parasuizidwiederholungen und eine Subgruppe mit ambivalenter Motivstruktur (interpersonell und todesorientiert).  相似文献   
90.
Cytokines play a part in the control of cellular growth, differentiation and development. Given such pleiotropic activities, it is not unexpected that the expression of the cytokines is tightly regulated. When cytokine-mediated processes are altered by mutation and/or overexpression of some cytokine or cytokine receptor genes, oncogenic transformation can occur. Oncogenes which derive their transforming potential through this mechanism include sis, which represents the activated form of the platelet-derived growth factor B chain, hst1/K-fgflint-2, which share appreciable homology with the gene family of fibroblast growth factors, fms, which is related to the cell surface receptor for macrophage-colony stimulating factor, and erbB-1, which encodes a truncated form of the epidermal growth factor receptor. Cytokine treatment has resulted in modulation of aberrant oncogene activity in some model systems.  相似文献   
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