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   1387篇
  免费   78篇
  国内免费   4篇
电工技术   15篇
综合类   1篇
化学工业   340篇
金属工艺   25篇
机械仪表   19篇
建筑科学   52篇
矿业工程   12篇
能源动力   48篇
轻工业   92篇
水利工程   8篇
石油天然气   12篇
无线电   104篇
一般工业技术   381篇
冶金工业   85篇
原子能技术   28篇
自动化技术   247篇
  2024年   2篇
  2023年   17篇
  2022年   16篇
  2021年   51篇
  2020年   35篇
  2019年   39篇
  2018年   36篇
  2017年   51篇
  2016年   41篇
  2015年   49篇
  2014年   64篇
  2013年   117篇
  2012年   92篇
  2011年   110篇
  2010年   69篇
  2009年   56篇
  2008年   88篇
  2007年   78篇
  2006年   58篇
  2005年   56篇
  2004年   37篇
  2003年   49篇
  2002年   43篇
  2001年   18篇
  2000年   13篇
  1999年   13篇
  1998年   13篇
  1997年   19篇
  1996年   14篇
  1995年   9篇
  1994年   13篇
  1993年   13篇
  1992年   7篇
  1991年   7篇
  1990年   5篇
  1989年   11篇
  1987年   3篇
  1986年   3篇
  1985年   2篇
  1984年   6篇
  1983年   7篇
  1982年   5篇
  1981年   2篇
  1980年   3篇
  1979年   7篇
  1976年   3篇
  1971年   5篇
  1969年   2篇
  1955年   1篇
  1954年   1篇
排序方式: 共有1469条查询结果,搜索用时 125 毫秒
1.
At times, people keep their emotions from showing during social interactions. The authors' analysis suggests that such expressive suppression should disrupt communication and increase stress levels. To test this hypothesis, the authors conducted 2 studies in which unacquainted pairs of women discussed an upsetting topic. In Study 1, one member of each pair was randomly assigned to (a) suppress her emotional behavior, (b) respond naturally, or (c) cognitively reappraise in a way that reduced emotional responding. Suppression alone disrupted communication and magnified blood pressure responses in the suppressors' partners. In Study 2, suppression had a negative impact on the regulators' emotional experience and increased blood pressure in both regulators and their partners. Suppression also reduced rapport and inhibited relationship formation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
2.
There is widespread application of indicators to the assessment of environmental condition of streams. These indicators are intended for use by managers in making various comparative and absolute assessments and often have a role in resource allocation and performance assessment. Therefore, the problem of formally defining confidence in the results is important but difficult because the sampling strategies used are commonly based on a compromise between the requirements of statistical rigour and the pragmatic issues of access and resources. It is rare to see this compromise explicitly considered and consequently there is seldom quantification of the uncertainty that could affect the confidence a manager has in an indicator. In this paper, we present a method for quantitatively assessing the tradeoffs between sampling density and uncertainty in meeting various monitoring objectives. Assessments using judgement‐based representative reaches are shown to be unreliable; instead a sampling approach is recommended based on the random selection of measuring sites. A detailed dataset was collected along two streams in Victoria, Australia, and the effect of sampling density was assessed by subsampling from this dataset with precision related to the number of sites assessed per reach length and the intensity of the sampling at each site. The sampling scheme to achieve a given precision is shown to depend on the monitoring objective. In particular, three objectives were considered: (1) making a baseline assessment of current condition; (2) change detection; and (3) detection of a critical threshold in condition. Change detection is shown to be more demanding than assessing baseline condition with additional sampling effort required to achieve the same precision. Sampling to detect a critical threshold depends on nominating acceptable values of Type I and II error and the size of the effect to be detected. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   
3.
This paper analyses the load influence on a d.c. drive motor servo system for all six degrees of freedom of industrial robots with an articulated configuration. Through the analyses, the analytical equations of total inertia and gravitation moments of an industrial robot servo system for external coordinate function were obtained. A mathematical model of an electro-mechanical industrial robot system was also developed.  相似文献   
4.
随着广播、电信和IT业的融合,未来的电话和数字电视都将成为互联网上的应用,这样就需要采用新型的客户端设备(CPE)和网络基础设施,以适应更高数据传输速率的要求,并满足新出现的DVB—T/S/C标准以及符合当前和提议中的通讯要求。  相似文献   
5.
6.
7.
8.
Growth of aerobic mesophilic bacteria in mixed salad without dressing, containing cooked sweet corn and raw endive, was similar to that of raw endive alone. At 9°C, sweet corn permitted the growth of the lactic acid bacterium Leuconostoc mesenteroides , whenever the bacterium was present on raw endive, whereas no growth of lactic acid bacteria was recorded on raw endive alone. Listeria monocytogenes , artificially inoculated in the samples, grew more in the mixed salad than in the raw endive alone, for products stored at 6°C and 9°C. Acidification of sweet corn to pH 5.0 was proposed to reduce the development of L. monocytogenes in the mixed salad to a level similar to that recorded in the raw endive alone. Acidification with citric acid reduced spoilage of sweet corn, whereas acetic acid caused necrosis on the leaves of raw endive.  相似文献   
9.
10.
Subchronic intoxication was induced in outbred male rats by repeated intraperitoneal injections with lead oxide (PbO) and/or cadmium oxide (CdO) nanoparticles (NPs) 3 times a week during 6 weeks for the purpose of examining its effects on the contractile characteristics of isolated right ventricle trabeculae and papillary muscles in isometric and afterload contractions. Isolated and combined intoxication with these NPs was observed to reduce the mechanical work produced by both types of myocardial preparation. Using the in vitro motility assay, we showed that the sliding velocity of regulated thin filaments drops under both isolated and combined intoxication with CdO–NP and PbO–NP. These results correlate with a shift in the expression of myosin heavy chain (MHC) isoforms towards slowly cycling β–MHC. The type of CdO–NP + PbO–NP combined cardiotoxicity depends on the effect of the toxic impact, the extent of this effect, the ratio of toxicant doses, and the degree of stretching of cardiomyocytes and muscle type studied. Some indices of combined Pb–NP and CdO–NP cardiotoxicity and general toxicity (genotoxicity included) became fully or partly normalized if intoxication developed against background administration of a bioprotective complex.  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