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   3295篇
  免费   105篇
  国内免费   5篇
电工技术   35篇
综合类   1篇
化学工业   274篇
金属工艺   17篇
机械仪表   40篇
建筑科学   72篇
矿业工程   4篇
能源动力   34篇
轻工业   131篇
水利工程   15篇
石油天然气   7篇
无线电   307篇
一般工业技术   396篇
冶金工业   1765篇
原子能技术   23篇
自动化技术   284篇
  2022年   15篇
  2021年   21篇
  2020年   28篇
  2019年   28篇
  2018年   36篇
  2017年   28篇
  2016年   28篇
  2015年   46篇
  2014年   37篇
  2013年   119篇
  2012年   49篇
  2011年   77篇
  2010年   56篇
  2009年   42篇
  2008年   73篇
  2007年   57篇
  2006年   56篇
  2005年   55篇
  2004年   60篇
  2003年   49篇
  2002年   50篇
  2001年   35篇
  2000年   48篇
  1999年   96篇
  1998年   516篇
  1997年   345篇
  1996年   189篇
  1995年   113篇
  1994年   107篇
  1993年   118篇
  1992年   43篇
  1991年   37篇
  1990年   52篇
  1989年   39篇
  1988年   33篇
  1987年   27篇
  1986年   42篇
  1985年   46篇
  1984年   23篇
  1983年   40篇
  1982年   28篇
  1981年   37篇
  1980年   31篇
  1978年   20篇
  1977年   60篇
  1976年   101篇
  1975年   19篇
  1974年   12篇
  1972年   13篇
  1970年   14篇
排序方式: 共有3405条查询结果,搜索用时 15 毫秒
991.
The meaning of medication and the way in which people use medicines has been the focus of a number of studies in recent years. However, there has been little attention directed to the meaning and management of neuroleptic medication by people who have received a diagnosis of schizophrenia. This topic is highly relevant to policy because of the central role given to neuroleptics in contemporary mental health and community care services. Using data from in-depth interviews with people with a diagnosis of schizophrenia we explore patients reasons for taking neuroleptics and the ways in which patients self-regulate their medication. The data suggest that the main utility of taking neuroleptic medication is to control specific symptoms and to gain personal control over managing symptoms. The costs of taking medication were side-effects which at times equalised or outweighed the positive gains of the neuroleptic medication. Patient accounts suggest that everyday medication practices are to a significant degree related to a policy context which stresses the need to survey and control the behaviour of people living in the community and the wider meaning and symbolic significance that schizophrenia has for patients in their everyday lives. For this reason, self regulatory action in this group of patients tends to be less evident and the threat of external social control greater than patients taking medication for other chronic conditions. The findings suggest the need to develop a collaborative patient-centred model of medication management for patients diagnosed with schizophrenia.  相似文献   
992.
A high-powered semiconductor diode laser (805 nm) has recently been developed for medical use. The laser-tissue interactions of this wavelength have been compared with Nd:YAG (1064 nm). When used in the contact mode, the extent of tissue vaporization and zones of thermal necrosis produced by these two lasers were similar. The diode laser was also an effective and haemostatic laser scalpel. This compact laser unit has potential advantages over existing Nd:YAG lasers.  相似文献   
993.
994.
To identify plant defense responses that limit pathogen attack, Arabidopsis eds mutants that exhibit enhanced disease susceptibility to the virulent bacterial pathogen Pseudomonas syringae pv maculicola ES4326 were previously identified. In this study, we show that each of four eds mutants (eds5-1, eds6-1, eds7-1, and eds9-1) has a distinguishable phenotype with respect to the degree of susceptibility to a panel of bacterial phytopathogens and the ability to activate pathogenesis-related PR-1 gene expression after pathogen attack. None of the four eds mutants exhibited observable defects in mounting a hypersensitive response. Although all four eds mutants were also capable of mounting a systemic acquired resistance response, enhanced growth of P. s. maculicola ES4326 was still apparent in the secondarily infected leaves of three of the eds mutants. These data indicate that eds genes define a diverse set of previously unknown defense responses that affect resistance to virulent pathogens.  相似文献   
995.
996.
A number of steroids seem to have anesthetic effects resulting primarily from their ability to potentiate currents gated by gamma-aminobutyric acidA (GABAA) receptor activation. One such compound is (3alpha,5alpha, 17beta)-3-hydroxyandrostane-17-carbonitrile [(+)-ACN]. We were interested in whether carbonitrile substitution at other ring positions might result in other pharmacological consequences. Here we examine effects of (3beta,5alpha, 17beta)-17-hydroxyestrane-3-carbonitrile [(+)-ECN] on GABAA receptors and Ca2+ channels. In contrast to (+)-ACN, (+)-ECN does not potentiate GABAA-receptor activated currents, nor does it directly gate GABAA-receptor mediated currents. However, both steroids produce an enantioselective reduction of T-type current. (+)-ECN blocked T current with an IC50 value of 0.3 microM with a maximal block of 41%. (+)-ACN produced a partial block of T current (44% maximal block) with an IC50 value of 0.4 microM. Block of T current showed mild use- and voltage-dependence. The (-)-ECN enantiomer was about 33 times less potent than (+)-ECN, with an IC50 value of 10 microM and an amount of maximal block comparable to (+)-ECN. (+)-ECN was less effective at blocking high-voltage-activated Ca2+ current in DRG neurons (IC50 value of 9. 3 microM with maximal block of about 27%) and hippocampal neurons. (+)-ECN (10 microM) had minimal effects on voltage-gated sodium and potassium currents in rat chromaffin cells. The results identify a steroid with no effects on GABAA receptors that produces a partial inhibition of T-type Ca2+ current with reasonably high affinity and selectivity. Further study of steroid actions on T currents may lead to even more selective and potent agents.  相似文献   
997.
43 college students suffering from recurrent tension headache were randomly assigned to 1 of 4 EMG biofeedback training conditions. Although all Ss were led to believe they were learning to decrease frontal EMG activity, actual feedback was contingent on decreased EMG activity for half of the Ss and increased EMG activity for the other half. Within these 2 groups, Ss also viewed bogus video displays designed to convince them they were achieving large (high success) or small (moderate success) reductions in EMG activity. Results show that regardless of actual changes in EMG activity, Ss receiving high-success feedback had substantially greater improvement in headache activity (53%) than Ss receiving moderate success feedback (26%). Performance feedback was also related to score changes in locus of control and self-efficacy measures administered pre- and posttreatment. Changes in these 2 cognitive variables during biofeedback training were correlated with reductions in headache activity following treatment, while changes in EMG activity exhibited during training were uncorrelated with outcome. (54 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
998.
999.
1000.
The literature on many different types of management programs says that effective program installations depend on the level of top management commitment: the stronger the commitment, the greater the potential for program success. A meta-analysis of 18 studies that evaluated the impact of management by objectives was presented to test this hypothesis. Results showed that the gain in job satisfaction was approximately one third of one standard deviation when top management had high commitment to program implementation. Little improvement was found in studies that had moderate or low commitment from top management. (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