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   40051篇
  免费   2104篇
  国内免费   142篇
耳鼻咽喉   527篇
儿科学   2567篇
妇产科学   697篇
基础医学   4788篇
口腔科学   1126篇
临床医学   2905篇
内科学   7201篇
皮肤病学   1133篇
神经病学   2351篇
特种医学   1180篇
外科学   5997篇
综合类   1277篇
一般理论   17篇
预防医学   2042篇
眼科学   1486篇
药学   4018篇
  1篇
中国医学   350篇
肿瘤学   2634篇
  2023年   332篇
  2022年   967篇
  2021年   1637篇
  2020年   888篇
  2019年   994篇
  2018年   1384篇
  2017年   1018篇
  2016年   1336篇
  2015年   1339篇
  2014年   1982篇
  2013年   2239篇
  2012年   3145篇
  2011年   3061篇
  2010年   1843篇
  2009年   1441篇
  2008年   2051篇
  2007年   2077篇
  2006年   1892篇
  2005年   1672篇
  2004年   1557篇
  2003年   1317篇
  2002年   1133篇
  2001年   776篇
  2000年   713篇
  1999年   593篇
  1998年   265篇
  1997年   213篇
  1996年   218篇
  1995年   184篇
  1994年   155篇
  1993年   130篇
  1992年   351篇
  1991年   335篇
  1990年   363篇
  1989年   330篇
  1988年   287篇
  1987年   241篇
  1986年   234篇
  1985年   229篇
  1984年   177篇
  1983年   125篇
  1982年   70篇
  1981年   75篇
  1980年   69篇
  1979年   109篇
  1978年   71篇
  1977年   87篇
  1976年   65篇
  1973年   62篇
  1971年   60篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
Intravascular papillary endothelial hyperplasia (IPEH) is an unusual vascular lesion of proliferating endothelial cells. It is more frequently seen in the extremities, particularly in the fingers. Oral IPEH has been reported with the common sites being lip, tongue, and buccal mucosa. In this article, we present a case of oral IPEH of the floor of the mouth, an unusual location, presenting in a 9-month-old male. The histogenesis, histologic features, and ultrastructural features are also reviewed. A misdiagnosis of angiosarcoma can be made in a case of IPEH due to similar histopathologic features. It is imperative to rule out this error by an elaborate histopathologic evaluation ofthese lesions.  相似文献   
72.
73.
It is clear that the vitamin D endocrine system plays a central role in the maintenance of calcium and phosphate homeostasis. It may be involved in the cellular differentiation and growth of various cells. Investigation of these properties in the future is likely to yield interesting information concerning the biology of this sterol hormone.  相似文献   
74.
75.
Epidemiological studies have indirectly linked compounds ofchromium, nickel and arsenic to human carcinogenesis. However,there is no evidence that metal compounds can transform humancells to the tumorigenic phenotype in culture. We show herethat exposure to 36 µM NiS04 for 48–96 h resultsin transformation of an immortal, non-tumorigenic, osteoblast-likecell line, HOS TE85, to the tumorigenic phenotype. Continuouspassaging following treatment leads to the formation of a fewdense foci. The cells isolated and expanded from the foci aremorphologically transformed, and form anchorage-independentcolonies of the size and abundance comparable to that formedby Kirsten murine sarcoma virus transformed HOS TE85 cells.The transformed cells from tumors in nude mice, have enhancedlevels of plasminogen activators and have lost the ability toform model bone matrix on extended culture in the presence ofascorbic acid and ß-glycerophosphate. A number ofcell lines have been established from nude mouse tumors. Cytogeneticanalysis reveals 16 marker chromosomes and an aberrant chromosome16. This is the first report of the transformation of a humancell line to tumorigenic phenotype by a metal carcinogen.  相似文献   
76.
77.
Role of Natural Killer Cell Subsets in Cardiac Allograft Rejection   总被引:2,自引:0,他引:2  
To achieve donor-specific immune tolerance to allogeneic organ transplants, it is imperative to understand the cell types involved in acute allograft rejection. In wild-type mice, CD4(+) T cells are necessary and sufficient for acute rejection of cardiac allografts. However, when T-cell responses are suboptimal, such as in mice treated with costimulation-targeting agents or in CD28-deficient mice, and perhaps in transplanted patients taking immunosuppressive drugs, the participation of other lymphocytes such as CD8(+) T cells and NK1.1(+) cells becomes apparent. We found that host NK but not NKT cells were required for cardiac rejection. Ly49G2(+) NK cells suppressed rejection, whereas a subset of NK cells lacking inhibitory Ly49 receptors for donor MHC class I molecules was sufficient to promote rejection. Notably, rejection was independent of the activating receptors Ly49D and NKG2D. Finally, our experiments supported a mechanism by which NK cells promote expansion and effector function of alloreactive T cells. Thus, therapies aimed at specific subsets of NK cells may facilitate transplantation tolerance in settings of impaired T-cell function.  相似文献   
78.
We present a case of wooden foreign bodies in the foot with delayed diagnosis. Unreliability of plain radiographs in these situations is emphasized. The comparative utility of computed tomography, magnetic resonance scans and ultrasonography is evaluated from a literature review. We utilized a sinogram which showed the splinters and also indicated their location and orientation in a region of complex anatomy, thus reducing surgical time and morbidity. Management of a suspected radiolucent foreign body is fraught with pitfalls and we provide a possible algorithm for management.  相似文献   
79.
This paper examines the role of selective serotonin reuptake inhibitors (SSRIs) in the treatment of hepatitis-C virus (HCV) patients who have developed interferon-α induced depression. A 2-year data analysis of HCV psychiatric liaison clinic has been undertaken. The diagnosis, treatment, and progress of those patients who were treated with interferon-α (INF-α) are reported. 53 of the 78 patients enrolled at the HCV Clinic and treated with INF-α were referred for psychiatric consultation. Six patients developed major depressive illness following INF therapy. They were all treated with SSRIs and they made full recovery. This is a significant observation and is concordant with other studies. Its biochemical ramifications are presented. It is concluded that INF-induced depression is fully reversible. A hypothesis is proposed that SSRIs modulate the neuro-protective neurotoxic ratio by possibly inhibiting the indole-2,3-dioxygenase induction of the kynurenine pathway.  相似文献   
80.
目的:比较儿童期癌症标准疗法与Ⅲ期随机化临床试验阶段所验证的新疗法,研究新疗法优于或劣于标准疗法的概率;此类临床试验中,纳入患者的民族因素可能对试验结果造成不确定性影响,所以,本文还研究新疗法的成功和失败模式是否与前述不确定性影响之间存在一致性。试验设计:临床观  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