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   12445篇
  免费   990篇
  国内免费   71篇
耳鼻咽喉   73篇
儿科学   296篇
妇产科学   202篇
基础医学   1551篇
口腔科学   226篇
临床医学   1631篇
内科学   2399篇
皮肤病学   178篇
神经病学   1254篇
特种医学   578篇
外国民族医学   1篇
外科学   2003篇
综合类   196篇
现状与发展   1篇
一般理论   9篇
预防医学   1007篇
眼科学   223篇
药学   919篇
中国医学   48篇
肿瘤学   711篇
  2023年   53篇
  2021年   224篇
  2020年   133篇
  2019年   204篇
  2018年   273篇
  2017年   194篇
  2016年   205篇
  2015年   220篇
  2014年   383篇
  2013年   474篇
  2012年   746篇
  2011年   899篇
  2010年   424篇
  2009年   427篇
  2008年   667篇
  2007年   802篇
  2006年   647篇
  2005年   734篇
  2004年   620篇
  2003年   602篇
  2002年   596篇
  2001年   234篇
  2000年   264篇
  1999年   253篇
  1998年   172篇
  1997年   149篇
  1996年   151篇
  1995年   120篇
  1994年   110篇
  1993年   111篇
  1992年   159篇
  1991年   134篇
  1990年   140篇
  1989年   149篇
  1988年   137篇
  1987年   145篇
  1986年   121篇
  1985年   163篇
  1984年   130篇
  1983年   93篇
  1982年   81篇
  1981年   87篇
  1980年   72篇
  1979年   82篇
  1978年   65篇
  1977年   68篇
  1976年   59篇
  1975年   38篇
  1974年   46篇
  1972年   46篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
High-dose gadoteridol in MR imaging of intracranial neoplasms.   总被引:6,自引:0,他引:6  
Twelve patients with a high suspicion of brain metastases by previous clinical or radiologic examinations were studied in a phase III investigation with magnetic resonance (MR) imaging at 1.5 T after a bolus intravenous injection of 0.1 mmol/kg gadoteridol followed at 30 minutes by a second bolus injection of 0.2 mmol/kg gadoteridol. All lesions were best demonstrated (showed greatest enhancement) at the 0.3-mmol/kg (cumulative) dose, with image analysis confirming signal intensity enhancement in the majority of cases after the second gadoteridol injection. More lesions were detected with the 0.3-mmol/kg dose than with the 0.1-mmol/kg dose, and more lesions were detected with the 0.1-mmol/kg dose than on precontrast images. In this limited clinical trial, high-dose gadoteridol injection (0.3-mmol/kg cumulative dose) provided improved lesion detection on MR images specifically in intracranial metastatic disease.  相似文献   
32.
33.
A study comparing the macular function of both eyes of 130 urological surgeons was carried out to investigate whether the increased light exposure to the endoscoping eye caused any deterioration of macular function. The non-endoscoping eye was used as a control. A sophisticated computer test of colour contrast sensitivity was used. The computer assesses the degree of brightness at which the subject is just able to detect a coloured grating, and for each eye this is expressed as a threshold for the red/green axis and the blue/yellow (tritan) axis. The subjects also completed a questionnaire about their working patterns and their general and ophthalmic history and had a brief examination of the fundus. The results do not suggest that urologists are suffering any significant macular damage as a result of their work with endoscopes.  相似文献   
34.
35.
N C Dean  W C Amend  M A Matthay 《Chest》1987,91(4):619-620
A 21-year-old man developed the adult respiratory distress syndrome (ARDS) within five hours of receiving antilymphocyte globulin. No other identifiable cause of ARDS was present. The mechanism for development of acute lung injury is unknown, but may be related either to direct lung cytotoxicity or to complement-mediated leukocyte and platelet destruction with secondary lung injury from inflammatory mediators.  相似文献   
36.
Although major tissue trauma produces profound depression of cell-mediated immunity, it is not known whether surgical trauma (i.e., midline laparotomy) has any adverse effect on the antigen presentation function and membrane interleukin-1 (IL-1) activity of peritoneal macrophages. To study this, C3H/HEJ (endotoxin-tolerant) mice were anesthetized. An approximately 1-inch midline abdominal incision was made, followed by abdominal closure. On days 1, 3, 5, and 7, peritoneal macrophages were harvested by means of peritoneal lavage, and antigen presentation capability was tested by incubating various numbers of peritoneal macrophages with 2 X 10(4) D10.G4.1 cells per well in the presence of conalbumin (400 micrograms/ml). The T helper cell clone (D.10.G4.1) proliferates on recognition of conalbumin in the context of Iak and also proliferates in the presence of membrane-bound IL-1 plus concanavalin A. To measure membrane IL-1 expression in peritoneal macrophages, Concanavalin A (10 micrograms/ml) was substituted for conalbumin. Cultures were incubated for 72 hours, pulsed with tritiated thymidine, and harvested. Peritoneal macrophages from laparotomized mice induced significantly less T helper cell proliferation on days 1 and 3 in the antigen presentation assay (37% and 30%, respectively; p less than 0.05) and in the membrane IL-1 assay (14% and 10%, respectively; p less than 0.05) as compared with the control. This difference was not detectable on day 5. More effective antigen presentation capability (167% of control; p less than 0.05) was seen on day 7. Thus laparotomy by itself produces marked depression of both antigen presentation function and membrane IL-1 activity of peritoneal macrophages, which may enhance susceptibility to intra-abdominal sepsis.  相似文献   
37.
38.
Mechanisms of zinc (Zn) toxicity are incompletely understood and data regarding potential endocrine alterations in Zn toxicity are scarce. To examine mechanisms of Zn toxicity, day-old chicks were pair-fed diets containing 5280 ppm (Hz) or 73 ppm (CON) Zn. Impaired postnatal growth, independent of feed consumption, and multiple endocrinopathies were observed following short-term (1-2 weeks) exposure to the high Zn diet. Reduced levels of serum cholesterol, high-density lipoprotein cholesterol, and growth hormone were associated with HZ feeding. Depressed levels of circulating thyroid hormones and histological evidence that follicle area of thyroids from HZ birds was 63% less than CON indicated that impaired growth of HZ birds may be caused, in part, by reduced thyroidal function.  相似文献   
39.
We describe a two generation family with variable ulnar and radial ray reduction and midline craniofacial abnormalities. The features suggest a diagnosis of Weyers' ulnar ray/oligodactyly syndrome originally described in two isolated cases. Syndromes of ulnar ray reduction are briefly reviewed and the relationship between limb bud and midline development discussed.  相似文献   
40.
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