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   3547篇
  免费   35篇
  国内免费   2篇
电工技术   4篇
综合类   2篇
化学工业   217篇
金属工艺   36篇
机械仪表   31篇
建筑科学   32篇
能源动力   34篇
轻工业   118篇
水利工程   6篇
石油天然气   7篇
无线电   95篇
一般工业技术   257篇
冶金工业   2636篇
原子能技术   9篇
自动化技术   100篇
  2021年   11篇
  2020年   8篇
  2019年   11篇
  2018年   22篇
  2017年   12篇
  2016年   19篇
  2015年   21篇
  2014年   23篇
  2013年   84篇
  2012年   34篇
  2011年   35篇
  2010年   28篇
  2009年   27篇
  2008年   41篇
  2007年   44篇
  2006年   37篇
  2005年   27篇
  2004年   29篇
  2003年   38篇
  2002年   37篇
  2001年   32篇
  2000年   16篇
  1999年   107篇
  1998年   872篇
  1997年   501篇
  1996年   290篇
  1995年   177篇
  1994年   137篇
  1993年   160篇
  1992年   26篇
  1991年   36篇
  1990年   38篇
  1989年   44篇
  1988年   52篇
  1987年   54篇
  1986年   28篇
  1985年   43篇
  1983年   13篇
  1982年   17篇
  1981年   22篇
  1980年   28篇
  1979年   12篇
  1978年   16篇
  1977年   55篇
  1976年   118篇
  1975年   18篇
  1973年   8篇
  1972年   8篇
  1971年   8篇
  1970年   8篇
排序方式: 共有3584条查询结果,搜索用时 15 毫秒
1.
Lateral scattering of retrograde well implants is shown to have an effect on the threshold voltage of nearby devices. The threshold voltage of both NMOSFETs and PMOSFETs increases in magnitude for conventional retrograde wells, but for triple-well isolated NMOSFETs the threshold voltage decreases for narrow devices near the edge of the well. Electrical data, SIMS, and SUPREM4 simulations are shown that elucidate the phenomenon.  相似文献   
2.
3.
The transjugular intrahepatic portosystemic shunt procedure is an accepted treatment for adults with complications of portal hypertension. We performed a retrospective review of all pediatric TIPS placements performed at the University of California, San Francisco between 1990 and 1996. Twelve procedures were attempted in nine children, with a mean age (+/- SD) of 9.4 +/- 3.9 years (range, 5 to 15 years) and a mean weight of 31 +/- 18 kg (range, 16 to 70 kg). The indications for TIPS placement were portal hypertension complicated by chronic variceal hemorrhage not controlled with sclerotherapy (n = 7) and hypersplenism with thrombocytopenia (n = 2). TIPS placement was successfully completed initially in seven of nine (78%) patients. Unfavorable vascular anatomy was the cause of failure in two cases. The seven patients who underwent successful TIPS placement were followed up for an average of 136 days (range, 1 to 800 days); two still have patent shunts, three underwent liver transplantation, one had a splenorenal shunt after stenosis, and one died of underlying liver disease. Variceal bleeding was controlled in four of five patients who successfully underwent TIPS placement. Shunt occlusion occurred in four patients; patency was restored by transjugular shunt revision in three, and a splenorenal shunt was performed in one.  相似文献   
4.
PURPOSE: To assess the role postoperative mydriatics play after extracapsular cataract extraction (ECCE) and posterior chamber intraocular lens (IOL) implantation in causing iris modifications and in controlling inflammation. SETTING: Outpatients Department, Ninewells Hospital, Dundee, Scotland. METHODS: The prospective study comprised 136 patients who had standardized ECCE. Half the patients used a mydriatic for 2 weeks postoperatively. Anterior chamber activity, pain, and eye redness were evaluated at 2 weeks postoperatively; pupil shape, peripheral anterior synechias, IOL position, and iris adhesions, at 6 weeks. RESULTS: Iris-lens adhesions were significantly more common in the group using a mydriatic. There was no difference between the two groups in postoperative inflammation. CONCLUSION: Mydriatics should not be used routinely after ECCE with posterior chamber IOL implantation.  相似文献   
5.
In a prospective study we found good results concerning postoperative complications (21%), perioperative lethality (3.2%) and lethality during hospital stay (6.5%) after implantation of dynamic hip screws (DHS) in patients with per- and subtrochanteric fractures of the femur. The ability to walk, as well as housing and social care postoperatively and follow-up for at least six months after dismissal demonstrates the importance of these fractures for the elderly. One of three patients needs professional care, 21% at home, 13% in nursing homes. Six months after operation the lethality is nearly 20%, i.e. three times higher than in hospital. These are the essential data for all techniques of osteosynthesis used in patients with these fractures, which could only be documented in prospective studies.  相似文献   
6.
Gastric bacteria from cheetahs with gastritis were used to inoculate specific-pathogen free kittens and conventional mice. Helicobacter sp. and Gastrospirillum sp. colonized kittens, while only Gastrospirillum sp. colonized mice. In kittens, both bacterial species induced mild lymphofolliclar gastritis which did not change over the course of the 11 months observation period. In mice, Gastrospirillum sp. induced lymphoplasmacytic and follicular gastritis which increased in severity over 6 months and persisted for the 12 month observation period. Gastric ulcers and gastric mucosal hypertrophy were present in chronically infected mice. These results indicate that host but not bacterial factors influence the severity of gastritis, and that in mice, bacterial gastritis increases in severity with time and may lead to gastric ulceration in some individuals.  相似文献   
7.
8.
9.
10.
How critical is the therapeutic alliance in the treatment of sexual offenders? To date such process issues have been neglected in the field of sex offender treatment. This article reviews the literature on the influence on behavior change of therapist features, clients' perceptions, and the therapeutic alliance. Among the many therapist features identified as helpful are empathy, warmth, and being directive and rewarding. Therapists who are aggressively confrontational appear not to foster beneficial changes in their clients. These issues are directly related to treatment issues faced by therapists who work with sexual offenders, such as dealing with cognitive distortions, lack of empathy, and lack of motivation to change. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  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