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   9346篇
  免费   246篇
  国内免费   11篇
电工技术   96篇
综合类   14篇
化学工业   1965篇
金属工艺   147篇
机械仪表   131篇
建筑科学   518篇
矿业工程   47篇
能源动力   221篇
轻工业   868篇
水利工程   113篇
石油天然气   38篇
无线电   607篇
一般工业技术   1280篇
冶金工业   2492篇
原子能技术   102篇
自动化技术   964篇
  2021年   125篇
  2020年   106篇
  2019年   99篇
  2018年   110篇
  2017年   118篇
  2016年   130篇
  2015年   113篇
  2014年   171篇
  2013年   464篇
  2012年   295篇
  2011年   376篇
  2010年   300篇
  2009年   327篇
  2008年   399篇
  2007年   396篇
  2006年   344篇
  2005年   306篇
  2004年   261篇
  2003年   260篇
  2002年   236篇
  2001年   167篇
  2000年   168篇
  1999年   162篇
  1998年   211篇
  1997年   189篇
  1996年   164篇
  1995年   168篇
  1994年   152篇
  1993年   143篇
  1992年   147篇
  1991年   94篇
  1990年   123篇
  1989年   131篇
  1988年   133篇
  1987年   123篇
  1986年   125篇
  1985年   160篇
  1984年   154篇
  1983年   143篇
  1982年   145篇
  1981年   153篇
  1980年   114篇
  1979年   141篇
  1978年   127篇
  1977年   110篇
  1976年   102篇
  1975年   96篇
  1974年   94篇
  1973年   112篇
  1972年   61篇
排序方式: 共有9603条查询结果,搜索用时 187 毫秒
51.
52.
Electroabsorption optical modulators have been fabricated on GaInAs/GaInAsP multiquantum well structures whose bandgap had been increased by laser photoabsorption-induced disordering. Modulation depths of 20 dB have been obtained in material which has been bandgap blue shifted by as much as 120 nm, while samples shifted by 80 nm gave depths as high as 27 dB  相似文献   
53.
Three methods of accounting for case manager effects in tests of the efficacy of mental health services are explored. These methods include (1) treating the case manager as a fixed factor, (2) treating the case manager as a random factor, and (3) examining service effects within the case manager. They are demonstrated with data from a nationally known case management program serving individuals with serious and persistent mental illness. Specifically, 3 conceptually distinct types of services provided or brokered by case managers are identified: habilitation-rehabilitation, community support, and traditional psychiatric services. The effectiveness of each in improving clients' adjustment is then examined with multiple regression adjustment strategies and each of the 3 methods to account for case manager effects. The results provide strong support for effects attributable to case managers and some support for the efficacy of habilitation-rehabilitation and community support services beyond the effects of traditional psychiatric services. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
54.
Presents a model for conceptualizing 4 basic types of suicidality among substance abusers (avoidance of painful consequences, the depressive experience of "crashing," the threat of personal loss, and environmental strain) and offers practical tips for treating the problem. Four general forms of intervention are discussed: pacing the crisis encounter; desensitizing the patient's sense of desperation; talking frankly about the suicidality; and attending to one's own needs as a counselor. These crisis-intervention tips are intended to aid counselors in handling suicidality as it is manifested in substance-abusing populations. Tips and guidelines for suicidal risk assessment with drug and alcohol abusers are given. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
55.
Social typicality effects occur when people apply their attitudes more consistently toward typical than toward atypical category members presumably because attitudes are directed toward the prototypic category member. Four studies tested whether individuals also apply social policy attitudes more consistently toward typical than toward atypical persons affected by the policy. Study 1 used attitude concept maps to assess how extensively individuals spontaneously reference the typical person affected by a social policy. Death penalty proponents did so more than did opponents; welfare proponents and opponents did so equally. In 3 other studies, death penalty proponents displayed greater typicality effects in sentencing "convicted murderers" than did opponents, welfare proponents and opponents displayed equal typicality effects in evaluating cases of suspected welfare fraud, and individuals whose attitude concept maps about welfare referred more to persons displayed greater typicality effects than did individuals whose maps referred more to principles. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
56.
57.
58.
This article quantifies errors arising from various integration methods and from sampling density in the numerical estimation of colorimetric integrals, e.g., tristimulus values. Both data sampling density and various numerical integration method errors will be distinguished. A test is presented to quantify sampling interval requirements for accurate colorimetric calculations for various illuminants. © 1992 John Wiley & Sons, Inc.  相似文献   
59.
60.
A longitudinal design was used to test the effects of life events experienced by young adolescents and their parents. The criteria were the adolescents' depression, anxiety, and self-esteem. The longitudinal analysis revealed a significant effect for the adolescents' controllable, but not uncontrollable, negative events. However, causal analyses revealed that this effect was the result of the significant relation between initial adjustment and the subsequent occurrence of controllable life stress (e.g., school suspension). The longitudinal analysis also revealed the stress-protective role of positive events, but only with respect to girls' self-esteem. There was no longitudinal support for the role of the parents' negative life events. These findings do not support the etiological importance of an accumulation of relatively discrete negative events experienced by early adolescents and their parents, but they do suggest the need (a) to conceptualize (controllable) life stress as a dependent variable in future research on developmental psychopathology; (b) to examine gender differences in early adolescent life stress; and (c) to develop more sophisticated measures of family life stress. (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