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   119464篇
  免费   6169篇
  国内免费   139篇
耳鼻咽喉   1806篇
儿科学   5275篇
妇产科学   3956篇
基础医学   16489篇
口腔科学   3039篇
临床医学   8696篇
内科学   22641篇
皮肤病学   3479篇
神经病学   9323篇
特种医学   5166篇
外国民族医学   32篇
外科学   19568篇
综合类   1605篇
一般理论   29篇
预防医学   5987篇
眼科学   3401篇
药学   8448篇
中国医学   328篇
肿瘤学   6504篇
  2018年   990篇
  2017年   831篇
  2016年   1168篇
  2015年   1285篇
  2014年   1713篇
  2013年   2503篇
  2012年   3280篇
  2011年   3289篇
  2010年   2067篇
  2009年   2021篇
  2008年   3380篇
  2007年   3643篇
  2006年   3806篇
  2005年   3882篇
  2004年   3821篇
  2003年   3703篇
  2002年   3631篇
  2001年   7138篇
  2000年   7084篇
  1999年   5977篇
  1998年   1670篇
  1997年   1601篇
  1996年   1364篇
  1995年   1234篇
  1994年   1119篇
  1993年   1149篇
  1992年   3853篇
  1991年   3651篇
  1990年   3615篇
  1989年   3400篇
  1988年   3060篇
  1987年   2941篇
  1986年   2857篇
  1985年   2671篇
  1984年   1971篇
  1983年   1621篇
  1982年   953篇
  1981年   936篇
  1980年   785篇
  1979年   1852篇
  1978年   1366篇
  1977年   1125篇
  1976年   943篇
  1975年   1200篇
  1974年   1231篇
  1973年   1224篇
  1972年   1052篇
  1971年   993篇
  1970年   886篇
  1969年   795篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
52.
In 50 children, 4 months to 12 years of age, with minor head trauma non-target visual event-related potentials were performed and compared to a second registration of the potentials some months later. On following-up there was a clear tendency for a relative improvement of the latencies of the endogenous potentials. In this way non-target visual event-related potentials proved to be of value in the investigation of mental impairment in early childhood.  相似文献   
53.
Trypsin and Zymosan induce an increase in respiration activity of cultivated endothelial cells. These effects are not due to the production of oxygen radicals. The effect of trypsin will be explained by interfering with the cellular homeostasis of calcium. The stimulated respiration after incubation with zymosan may be connected with the increased phagocytosis.  相似文献   
54.
55.
Conformationally restricted analogues of the selective partial muscarinic agonist N-methyl-N-(1-methyl-4-pyrrolidino-2-butynyl)acetamide (BM 5; 2) were synthesized. The compounds were tested for muscarinic and antimuscarinic activity in the isolated guinea pig ileum and in intact mice. They were found to be moderately potent muscarinic antagonists or weak partial agonists. The new compounds were less potent than 2 in inhibiting (-)-[3H]-N-methylscopolamine binding in the rate cerebral cortex. Thus, structural modifications of 2 in which part of the amide moiety has been connected with the methyl group in the butynyl chain to form a five-membered ring decrease affinity and in most cases abolish efficacy.  相似文献   
56.
57.
The duodenal contents were examined in 81 patients with gastroduodenal ulcer. Bile acid concentrations, alkaline phosphatase activity, and sodium ion concentration were measured for the detection of duodenogastric reflux. Measurements of sodium ion concentration permitted estimation of the immediate volume of the duodenogastric reflux in the gastric contents. No methods for duodenogastric reflux detection should be given preference in examinations of peptic ulcer patients. Multiple-modality studies appear to be the most effective.  相似文献   
58.
The analysis of vestibular responses in a comatose patient often provides the critical information for making a correct preliminary diagnosis and directing the subsequent laboratory evaluation. Because of some uncertainties about what is being tested with the various bedside maneuvers that are used to elicit vestibular responses, we review the physiologic basis for the oculomotor responses that occur with head rotation or with caloric stimuli. We further urge precise and unambiguous terminology to describe both stimulus and response. We suggest using physiologically well-defined terms such as vestibulo-ocular reflex and cervico-ocular reflex and avoiding potentially misleading terms such as the doll's head and the oculocephalic maneuvers.  相似文献   
59.
60.
Influence of mesh materials on collagen deposition in a rat model.   总被引:5,自引:0,他引:5  
Alterations of the extracellular matrix (ECM) with its major component collagen are increasingly discussed as possible risk factors implicated in the development of abdominal-wall herniation. Because of the widespread use of alloplastic meshes for the surgical repair of hernias, an animal study was performed to analyze the influence of various mesh materials on the quantity and quality of collagen deposition. In 60 male Sprague-Dawley rats an abdominal replacement was performed using three different kinds of mesh materials: polyester (PE), a pure polypropylene (PP), and a composite mesh made of polypropylene and polyglactin (PG). A simple fascia suture repair served as control. The count of fibroblasts, the collagen/protein ratio, the type I/III collagen ratio, and the expression of basic fibroblast growth factor (b-FGF) at the interface were analyzed after 7, 21, and 90 days. The ratio of collagen to overall protein (microg/mg) showed significant differences comparing different mesh materials (sham controls 38.44 +/- 16.33 microg/mg, PE 68.5 +/- 23.8 microg/mg, PP 101.6 +/- 32.3 microg/mg, PG 49.6 +/- 11.6 microg/mg at day 90). The ratio of collagen type I/III increased over time in all groups. However, 90 days after mesh implantation the ratio was always significantly lowered compared to the controls. No significant difference was found comparing different mesh materials. The alteration of the scar composition is closely connected to an increased b-FGF expression. b-FGF and count of fibroblasts highly correlated (r =.95) and showed significant elevated levels compared to simple suture repair. The results of our study strongly support the notion that wound healing is affected by mesh implantation. The quality of the ECM deposition as determined by collagen type I/III ratio is impaired in general, whereas the quantity of ECM deposition is markedly influenced by the kind of mesh material.  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