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   1329600篇
  免费   95952篇
  国内免费   2896篇
耳鼻咽喉   19762篇
儿科学   40207篇
妇产科学   38655篇
基础医学   186591篇
口腔科学   39762篇
临床医学   112094篇
内科学   260741篇
皮肤病学   30157篇
神经病学   106016篇
特种医学   53630篇
外国民族医学   435篇
外科学   207740篇
综合类   30986篇
现状与发展   6篇
一般理论   436篇
预防医学   91618篇
眼科学   31303篇
药学   99954篇
  2篇
中国医学   2978篇
肿瘤学   75375篇
  2018年   11737篇
  2015年   11872篇
  2014年   16684篇
  2013年   25244篇
  2012年   32999篇
  2011年   34866篇
  2010年   20734篇
  2009年   20231篇
  2008年   33580篇
  2007年   36678篇
  2006年   37258篇
  2005年   36013篇
  2004年   35091篇
  2003年   34070篇
  2002年   33593篇
  2001年   63627篇
  2000年   65329篇
  1999年   55395篇
  1998年   14653篇
  1997年   13397篇
  1996年   12104篇
  1995年   12130篇
  1994年   11395篇
  1992年   42710篇
  1991年   41280篇
  1990年   40539篇
  1989年   39529篇
  1988年   36933篇
  1987年   36398篇
  1986年   34876篇
  1985年   33094篇
  1984年   24786篇
  1983年   20990篇
  1982年   12612篇
  1981年   11504篇
  1980年   10710篇
  1979年   23873篇
  1978年   17023篇
  1977年   14768篇
  1976年   13339篇
  1975年   15229篇
  1974年   18054篇
  1973年   17547篇
  1972年   16793篇
  1971年   15705篇
  1970年   14887篇
  1969年   14330篇
  1968年   13440篇
  1967年   11990篇
  1966年   11247篇
排序方式: 共有10000条查询结果,搜索用时 437 毫秒
991.
992.
The disintegrin and metalloproteinase 10 (ADAM10) is a membrane‐anchored metalloproteinase with both proteolytic and disintegrin characteristics. Here, we investigate the expression, regulation, and functional role of ADAM10 in axonal outgrowth and myelination of the peripheral nerve. Expression pattern analysis of 11 ADAM family members in co‐cultures of rat dorsal root ganglia (DRG) neurons and Schwann cells (SCs) demonstrated the most pronounced mRNA expression for ADAM10. In further studies, ADAM10 was found to be consistently upregulated in DRG‐SC co‐cultures before the induction of myelination. Neurons as well as SCs widely expressed ADAM10 at the protein level. In neurons, the expression of ADAM10 was exclusively limited to the axons before the induction of myelination. Inhibition of ADAM10 activity by the hydroxamate‐based inhibitors GI254023X and GW280264X resulted in a significant decrease in the mean axonal length. These data suggest that ADAM10 represents a prerequisite for myelination, although its activity is not required during the process of myelination itself as demonstrated by expression analysis of myelin protein zero (P0) and Sudan black staining. Hence, during the process of myelin formation, ADAM10 is highly upregulated and appears to be critically involved in axonal outgrowth that is a requirement for myelination in the peripheral nerve. © 2009 Wiley‐Liss, Inc.  相似文献   
993.
Designed to help persons with schizophrenia to persist and perform better at job placements, the Indianapolis Vocational Intervention Program (IVIP) is a program of cognitive-behavioral group and individual interventions. While its feasibility has been previously demonstrated, it is unknown whether IVIP assists persons to achieve greater levels of participation in vocational rehabilitation and higher levels of job performance. In this study, 100 participants with schizophrenia or schizoaffective disorder were offered a six month job placement and randomized to receive IVIP (n = 50) or support services (n = 50) matched for treatment intensity. Number of hours worked was recorded weekly and job performance was assessed biweekly using the Work Behavior Inventory with raters blind to condition. t-tests revealed that participants in the IVIP group worked a significantly greater number of weeks than those in the support condition. Also, repeated measures ANOVA revealed the IVIP group worked more hours across that 26 week period as well. And with regards to work performance, repeated measures of the 56 participants who worked for at least two-thirds of the intervention revealed that participants in the IVIP group had generally better work performance than those in the support condition. Results suggest a connection between cognitive-behavioral interventions and higher levels of work performance in people with schizophrenia.  相似文献   
994.
骨细胞(osteocyte)是在矿化骨基质内名副其实的骨的细胞(bonecell)。通过细胞突触,骨细胞彼此相连,很可能也与骨髓中某些细胞相接,从而形成三维细胞网络。从骨的超微结构看,骨细胞处于很理想的位置,可以担当骨生理的重要调节因子。然而,由于骨细胞处于矿化骨基质深层,对其功能了解甚少。但随着新技术方法的应用,就有可能对这种成骨细胞系中的终末分化细胞进行深入研究,人们也由此对骨细胞的兴趣大增。骨细胞被认为是骨的机械应力感受器,它有可能参与骨重建。骨细胞能分泌具有调节成骨细胞功能的硬骨素(sclerostin)。一种能降低肾脏磷回吸收的激素——调磷因子FGF23也主要源白骨细胞。随着我们对骨细胞了解的深入,清楚显示,骨细胞不仅能影响局部骨转换活性,而且对全身矿物质的体内平衡也有多种功能。因此,对骨细胞的研究,可以为代谢性骨病的治疗探索新的途径。  相似文献   
995.
996.
997.
Background: In elderly patients, opioids may cause prominent postoperative sedation and respiratory depression. We evaluated the influence of age on the effects of opioids and plasma concentrations of fentanyl and oxycodone in cardiac surgery patients.
Methods: Thirty (≥75 years, gender M9/F21) and 20 (≤60 years, gender M20/F0) patients scheduled to undergo cardiac surgery. A standard anesthesia with fentanyl as an opioid was used. Fentanyl plasma concentrations were measured at the end of surgery and 2 h later. After tracheal extubation, when the pain intensity was at least moderate, blood samples for fentanyl and oxycodone plasma concentration measurements were taken. Thereafter, oxycodone hydrochloride 0.05 mg/kg i.v. was administered. After 15 and 45 min, pain intensity, sedation and oxycodone plasma concentration were determined. This test protocol was repeated twice.
Results: The elderly had a higher plasma concentration of fentanyl at the end of surgery than younger patients (5.7±2.2 vs. 3.8±1.2 ng/ml, P =0.001). The plasma concentrations of oxycodone were comparable between the groups. The interval between the second and the third oxycodone dose was longer in the elderly patients ( P =0.036). Pain intensity on the verbal rating scale was lower at the 45-min assessment point after all three oxycodone test doses ( P =0.008) and sedation scores were significantly higher after the third dose in the elderly patients ( P =0.035).
Conclusions: In elderly patients, the plasma concentration of fentanyl was higher but plasma levels of oxycodone were at a similar level compared with middle-aged patients. However, the elderly patients had less pain and were more sedated after doses of oxycodone.  相似文献   
998.
999.
1000.
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