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   293898篇
  免费   25156篇
  国内免费   17286篇
耳鼻咽喉   2629篇
儿科学   3814篇
妇产科学   5677篇
基础医学   34209篇
口腔科学   5121篇
临床医学   36893篇
内科学   47872篇
皮肤病学   3436篇
神经病学   15880篇
特种医学   10729篇
外国民族医学   130篇
外科学   32722篇
综合类   42209篇
现状与发展   59篇
一般理论   61篇
预防医学   18567篇
眼科学   7991篇
药学   29760篇
  215篇
中国医学   13705篇
肿瘤学   24661篇
  2024年   851篇
  2023年   4153篇
  2022年   10338篇
  2021年   13679篇
  2020年   10071篇
  2019年   9078篇
  2018年   9596篇
  2017年   8437篇
  2016年   8101篇
  2015年   12090篇
  2014年   15225篇
  2013年   14530篇
  2012年   21180篇
  2011年   23166篇
  2010年   14352篇
  2009年   11538篇
  2008年   15606篇
  2007年   15771篇
  2006年   15118篇
  2005年   14995篇
  2004年   10698篇
  2003年   9577篇
  2002年   8391篇
  2001年   7475篇
  2000年   7523篇
  1999年   7712篇
  1998年   4354篇
  1997年   4369篇
  1996年   3361篇
  1995年   3056篇
  1994年   2655篇
  1993年   1768篇
  1992年   2753篇
  1991年   2377篇
  1990年   2032篇
  1989年   1769篇
  1988年   1525篇
  1987年   1422篇
  1986年   1135篇
  1985年   901篇
  1984年   604篇
  1983年   464篇
  1982年   284篇
  1981年   270篇
  1980年   228篇
  1979年   313篇
  1978年   178篇
  1977年   139篇
  1974年   152篇
  1973年   128篇
排序方式: 共有10000条查询结果,搜索用时 10 毫秒
11.
12.
晶体玻璃体视网膜联合手术治疗复杂性视网膜脱离   总被引:6,自引:2,他引:4  
目的探讨玻璃体视网膜手术(vitreretinalsurgery,VR术)联合晶体切除/超声粉碎的效果。方法对81例(81只眼)应用晶体玻璃体视网膜联合手术(lenticular-vitreoretinalsurgery,LVR术)治疗的复杂性视网膜脱离进行回顾性分析。结果解剖性成功者64只眼(79.01%),功能性成功者45只眼(55.56%);手术成功率显著降低的原因是前部增殖性玻璃体视网膜病变(proliferativevitreo-retinopathy,PVR)(成功率42.86%,P<0.01)和术中/术后眼内出血(成功率58.82%,P<0.025)。结论LVR术是治疗复杂性视网膜脱离的主要方法;显著影响手术预后的因素是前部PVR和术中/术后眼内出血。  相似文献   
13.
医源性胆管狭窄X线表现   总被引:1,自引:0,他引:1  
本文报道了13例医源性胆管狭窄,分析其影像表现。特点为:环形狭窄;线样狭窄,包括规则的和不规则的线样狭窄;闭塞性狭窄;胆管闭塞和胆管中断分离。ERCT和PCT对狭窄的形态,位置及长度显示优于CT和US。  相似文献   
14.
15.
16.
17.
The effects of intracellular Ca2+ (Ca2+i) on K+ currents in hippocampal cells were examined using acutely isolated cells obtained from adult guinea pigs. Whole-cell voltage-clamp recordings were carried out in a configuration that allowed a continuous perfusion of the intracellular medium. Recording media were made to block inward currents and allowed selective activation of K(+)-dependent outward currents. Voltage-dependent outward currents consisted of an initial rapidly decaying component followed by a sustained component. The time constant of decay of the transient current was about 25 msec, and previous studies (Numann et al., 1987) showed that the kinetic and pharmacological properties of this current closely resembled the A current recorded in invertebrate neurons (Connor and Stevens, 1971; Thompson, 1982). Intracellular perfusion of hippocampal cells with a solution containing elevated Ca2+ (about 4.5 x 10(-4) M) elicited outward currents at the holding potential (-45 to -55 mV) and produced changes in voltage-dependent K+ currents. The transient outward current (IA) activated by depolarization was suppressed with increases in Ca2+i. Delayed, sustained K+ currents were greatly potentiated. Data also showed that, among the 3 effects elicited by Ca2+i, suppression of IA was most sensitive to Ca2+i elevation. Previous results (Numann et al., 1987) showed that IA had a lower threshold (about -45 mV) than sustained currents (about -40 mV). By using low levels of depolarization (-40 mV), IA can be selectively activated, and the suppressive effect of Ca2+i on IA was confirmed on the kinetically isolated IA.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
18.
S R Roffler  M H Yu  B M Chen  E Tung  M Y Yeh 《Cancer research》1991,51(15):4001-4007
Pseudomonas exotoxin A (PE) linked to the F(ab')2 fragment of 1H10, a murine monoclonal antibody recognizing a carbohydrate epitope of a glycoconjugate expressed on the surface of human cervical carcinoma tumor cells, was evaluated for in vitro and in vivo activity. PE can kill cells by ADP-ribosylating elongation factor 2 thus inhibiting protein synthesis. Disulfide- as well as thioether-linked immunotoxins (1H10-PE) killed cervical carcinoma cells in vitro and were 20-160 times more inhibitory to target than to control cells. Cell killing was antibody mediated as demonstrated by the reduction of 1H10-PE growth inhibition to target CaSki cells by free 1H10 F(ab')2. In addition, a control antibody immunotoxin was nontoxic to CaSki cells. Thioether-linked 1H10-PE administered either i.v. or i.p. suppressed the growth of established solid s.c. cervical carcinoma tumors xenografted in nude mice for over 30 days. Treatment with antibody alone or a control immunotoxin had no significant effect on tumor growth. Administration of immunotoxin i.p. was associated with less toxicity than administration i.v., but i.v. injections were more effective at suppressing the growth of established solid tumors.  相似文献   
19.
Intravenous administration of human bone marrow stromal cells (hMSCs) after middle cerebral artery occlusion (MCAo) in rats provides functional benefit. We tested the hypothesis that these functional benefits are derived in part from hMSC production of growth and trophic factors. Quantitative sandwich enzyme‐linked immunosorbent assay (ELISA) of hMSCs cultured with normal and MCAo brain extracts were performed. hMSCs cultured in supernatant derived from ischemic brain extracts increased production of brain‐derived neurotrophic factor (BDNF), nerve growth factor (NGF), vascular endothelial growth factor (VEGF) and hepatocyte growth factor (HGF). These neurotrophins and angiogenic growth factors increased in a post‐ischemia time‐dependent manner. The hMSC capacity to increase expression of growth and trophic factors may be the key to the benefit provided by transplanted hMSCs in the ischemic brain.  相似文献   
20.
糖尿病患者腹部手术后消化道功能的观察   总被引:6,自引:0,他引:6  
目的了解糖尿病患者腹部手术后消化道功能恢复情况,为临床进行有针对性的护理提供依据.方法对72例糖尿病患者腹部手术后消化道功能恢复情况进行观察,并随机抽取70例非糖尿病腹部手术患者作对照.结果在肠鸣音恢复及肛门排气时间、进流质饮食后食欲状况、恶心呕吐、腹胀发生情况5个方面进行比较,两组消化道功能恢复差异明显(P均<0.01).结论糖尿病患者腹部手术后消化道功能恢复延迟,临床护理中应予重视.  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