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   645篇
  免费   9篇
化学工业   20篇
金属工艺   2篇
机械仪表   4篇
建筑科学   19篇
能源动力   9篇
轻工业   33篇
石油天然气   1篇
无线电   13篇
一般工业技术   39篇
冶金工业   502篇
自动化技术   12篇
  2023年   1篇
  2022年   1篇
  2021年   5篇
  2019年   1篇
  2018年   1篇
  2017年   2篇
  2015年   10篇
  2014年   5篇
  2013年   10篇
  2012年   8篇
  2011年   19篇
  2010年   4篇
  2009年   4篇
  2008年   5篇
  2007年   7篇
  2006年   1篇
  2005年   4篇
  2004年   6篇
  2003年   4篇
  2002年   2篇
  2001年   6篇
  2000年   7篇
  1999年   17篇
  1998年   139篇
  1997年   78篇
  1996年   66篇
  1995年   31篇
  1994年   29篇
  1993年   36篇
  1992年   6篇
  1991年   10篇
  1990年   9篇
  1989年   10篇
  1988年   7篇
  1987年   11篇
  1986年   7篇
  1985年   9篇
  1983年   4篇
  1982年   6篇
  1981年   1篇
  1980年   2篇
  1979年   1篇
  1978年   4篇
  1977年   19篇
  1976年   34篇
  1973年   2篇
  1972年   1篇
  1967年   1篇
  1960年   1篇
排序方式: 共有654条查询结果,搜索用时 15 毫秒
11.
Two generations of outcome research demonstrate the potential efficacy of marital therapy in the treatment of depression. After reviewing treatment outcome studies on marital therapy for depression, we examine basic research linking aspects of the marital relationship to depressive symptoms. In doing so, we highlight a number of theoretical perspectives and research findings that can inform work with couples in which one spouse is depressed. Finally, we identify potential innovations that may lead to a third generation of marital interventions for depression and several avenues of inquiry for a third generation of outcome research on marital therapy for depression.  相似文献   
12.
OBJECTIVES: To compare gastric tonometry (pHi) with estimates of pHi in ill injured patients, and to correlate pHi with haemodynamic variables. DESIGN: Prospective, non-interventional study. SETTING: ICU of Level I trauma centre, USA. MAIN OUTCOME MEASURES: 154 gastric tonometry measurements were compared with physicians' estimates of adequacy of resuscitation. Resuscitation was categorised as inadequate (pHi < 7.35) or adequate (pHi> or = 7.35). Measured and estimated pHi were also compared with oxygen delivery, oxygen consumption, cardiac index, mixed venous O2 saturation, and critical illness scores. RESULTS: Estimated pHi was often higher than measured pHi in the judgement of all four surgical intensive care physicians. Measured pHi correlated positively with mixed venous O2 tension (r = 0.21). There were significant negative correlations between measured pHi and both oxygen delivery (r = -0.25) and oxygen consumption (r = 0.28). Estimated pHi correlated positively with mean arterial pressure (r = 0.21) and hospital day (r = 0.26); it correlated negatively with pulmonary arterial elastance (r = -0.35). CONCLUSION: Experienced intensive care physicians tended to overestimate visceral perfusion, which suggests that gastric tonometry adds useful information over and above routine haemodynamic indices. Arterial blood pressure and mixed venous oxygen saturation correlated better with measured pHi than with other indices of perfusion.  相似文献   
13.
Front load carriage is a common occupational task in some industries (e.g. agriculture, construction), but, as compared to lifting tasks, relatively little research has been conducted on the biomechanical loading during these activities. The focus of this study was to explore the low back biomechanics during these activities and, specifically, to examine the effects of load height and walking speed on trunk muscle activity and trunk posture. Eleven male participants participated in two separate front load-carriage experiments. The first experiment called for carrying a barbell (with weight corresponding to 20% of elbow flexion strength) at three heights (knuckle height, elbow height and shoulder height) at a constant horizontal distance from the spine. The second experiment called for participants to carry a bucket of potatoes weighing 14 kg at the same three heights, but with no further restrictions in technique. In both experiments, the participants performed this task while either standing still or walking at a self-selected speed. As they performed these tasks, the activity levels of the right-side muscle of the rectus abdominis, external oblique, biceps brachii, anterior deltoid and three levels (T9, T12 and L3) of the erector spinae were sampled. Mid-sagittal plane trunk posture was also quantified using three magnetic field-based motion sensors at T9, T12 and L3. The results showed a significant effect of both walking speed and load height on trunk posture and trunk muscle activity levels in both the barbell and bucket experiments. In the barbell experiment, the walking trials generated 43% more trunk muscle activity than the standing trials. Trials at shoulder height produced 11% more muscle activity than trials at elbow height in the T9 erector spinae muscles and 71% more muscle activity in the anterior deltoid. In the bucket experiment, trunk muscle activity responded in a similar fashion, but the key result here was the quantification of the natural hyperextension posture of the spine used to balance the bucket of potatoes. These results provide insight into muscle activation patterns in dynamic settings, especially (load) carrying biomechanics, and have implications in industrial settings that require workers to carry loads in front of their bodies.  相似文献   
14.
15.
16.
Objective: Social psychological theories such as attribution theory have been applied to conditions such as depression and physical disability, but not to traumatic brain injury (TBI). The goal of this paper is to show that that attribution theory and related concepts help to explain the public's misconceptions about TBI and other challenges faced by clinicians and families of persons with TBI. Results: Research shows that misconceptions about brain injury occur because people misattribute the actions of persons with brain injury. These misattributions reflect two features: (a) the absence of visible markers of the injury, and (b) the tendency to compare persons with TBI with their peers rather than their own preinjury performance. These two processes lead to the opposite pattern to the stigma that occurs with visible disabilities: specifically, a failure among members of the public to recognize that problematic behaviors may result from the injury. This analysis suggests several therapeutic strategies for managing public misconceptions in ways that enhance coping and recovery. Conclusion: Clarifying the attribution processes that underpin misconceptions about brain injury provides a framework for enhancing rehabilitation and addressing these misconceptions effectively. (PsycINFO Database Record (c) 2011 APA, all rights reserved)  相似文献   
17.
Matching pursuits with a wave-based dictionary   总被引:10,自引:0,他引:10  
The method of matching pursuits utilizes a nonlinear iterative procedure to project a given waveform onto a particular dictionary. For scattering problems, the most appropriate dictionary is composed of wave objects that are consistent with the underlying wave phenomenology. A signal scattered from most targets of interest can be decomposed in terms of wavefronts, resonances, and chirps-and each of these subclasses can be further subdivided based on characteristic wave physics. Here, we investigate the efficacy of applying the method of matching pursuits with a wave-based dictionary for the processing of scattering data. The performance of this algorithm is examined for scattering data with and without additive noise  相似文献   
18.
19.
A case involving multiple bite marks is presented. The bite marks were photographed over a 31-day period to document the injuries and preserve their evidentiary value. The evidence recovered at each photography session is discussed and photographs are presented for review. Suggestions concerning the need for more research are presented.  相似文献   
20.
OBJECTIVE: The purpose of this study was to evaluate a hydroxylapatite-based material and calcium sulfate when each was used under a resin-modified glass ionomer cement to repair furcation perforations. STUDY DESIGN: Perforations of pulp chamber floors were made in 72 teeth of 9 dogs. Perforations were divided into 3 equal-sized groups and repaired with resin-modified glass ionomer either alone or over an artificial floor. The artificial floor was either a hydroxylapatite-based material or calcium sulfate. Three dogs were killed at each of 3 intervals (1, 3, and 6 months). The tissue response to the tested materials was evaluated clinically, radiographically, and histologically. RESULTS: The hydroxylapatite-based material showed the highest radiographic success; this was followed by calcium sulfate and glass ionomer. From histologic evaluation, the average success rate was found to be 67% for calcium sulfate, 62% for the hydroxylapatite-based material, and 59% for glass ionomer. However, there was no statistical significant difference with the resin-modified glass ionomer when it was used alone and when it was used over a barrier. There was also no significant difference between the hydroxylapatite-based material and the calcium sulfate when they were used as artificial floors. CONCLUSION: The use of an artificial floor may not be necessary when flowable resin-modified glass ionomer cements are used.  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