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   2867篇
  免费   166篇
  国内免费   2篇
电工技术   12篇
综合类   3篇
化学工业   720篇
金属工艺   34篇
机械仪表   16篇
建筑科学   133篇
矿业工程   4篇
能源动力   48篇
轻工业   487篇
水利工程   29篇
石油天然气   19篇
武器工业   1篇
无线电   130篇
一般工业技术   489篇
冶金工业   537篇
原子能技术   20篇
自动化技术   353篇
  2023年   13篇
  2022年   58篇
  2021年   118篇
  2020年   59篇
  2019年   48篇
  2018年   59篇
  2017年   89篇
  2016年   88篇
  2015年   87篇
  2014年   110篇
  2013年   157篇
  2012年   162篇
  2011年   199篇
  2010年   150篇
  2009年   131篇
  2008年   163篇
  2007年   159篇
  2006年   143篇
  2005年   103篇
  2004年   87篇
  2003年   85篇
  2002年   68篇
  2001年   56篇
  2000年   33篇
  1999年   52篇
  1998年   66篇
  1997年   53篇
  1996年   41篇
  1995年   29篇
  1994年   37篇
  1993年   39篇
  1992年   28篇
  1991年   19篇
  1990年   28篇
  1989年   22篇
  1988年   21篇
  1987年   21篇
  1986年   17篇
  1985年   23篇
  1984年   10篇
  1983年   16篇
  1982年   11篇
  1981年   6篇
  1980年   15篇
  1979年   6篇
  1978年   6篇
  1977年   10篇
  1974年   7篇
  1973年   4篇
  1960年   5篇
排序方式: 共有3035条查询结果,搜索用时 15 毫秒
1.
2.
The present concurrent study combined developmental and ecological considerations to examine the unique contribution of multiple preschool competencies to an indicator of early academic success. Participants included 195 Head Start children from 32 classrooms representative of a large, urban Head Start program. Dimensional (variable-centered) analyses revealed 3 distinct classroom competency dimensions (i.e., General Classroom Competencies, Specific Approaches to Learning, and Interpersonal Classroom Behavioral Problems). The first 2 of these dimensions were found to be uniquely associated with early academic success. Findings from typological (person-centered) analyses supported the dimensional findings. Typological analyses revealed 7 profiles of classroom competency distinguished by high scores on the dimensions of General Competencies and Approaches to Learning, and these profiles were found to relate differentially to the indicator of early academic success. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
3.
For many companies, productivity improvements are the watchwords of the 1990s. IS organizations are having to demonstrate increased productivity on an annual basis. For the end-user computing (EUC) department, this requirement often comes in addition to the request to quantify the services it provides, presenting the EUC manager with the proverbial nightmare of juggling two number-one priorities. Which should receive the highest attention? The savvy manager recognizes that the correct answer is both.  相似文献   
4.
X-ray diffraction and ab initio MO theoretical calculations were used in order to investigate the structural and electronic properties of sarmazenil, a weak inverse agonist at the omega modulatory sites (benzodiazepine receptors). This compound was compared to bretazenil, a partial agonist, and to the antagonist flumazenil on the basis of structural and electronic data. The conformational and theoretical properties (interatomic pi overlap populations, molecular electrostatic potential (MEP), the topology of frontier orbitals, and proton affinity) of these three imidazobenzodiazepinones were determined in order to analyse the stereoelectronic properties in relation with their distinct intrinsic efficacies at the omega modulatory sites.  相似文献   
5.
In a conceptual replication of A. Biglan et al (see record 1989-39898-001), 288 Ss rated their emotional and behavioral responses to aggressive, distressed, and neutral behaviors. The stimulus behaviors occurred in the context of casual relationships and were portrayed by male and female actors. Consistent with Biglan et al, it was found that aggressive behaviors evoked angry emotions and negative behavioral responses; distressed behaviors evoked both angry and concerned emotions and supportive behavioral responses. However, in contrast to the original results, evidence was also found of negative (primarily avoidant) behavioral responses to distressed behavior. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
6.
Longitudinal analyses on normal versus impaired functioning across 7 domains were conducted in children who had experienced profound institutional deprivation up to the age of 42 months and were adopted from Romania into U.K. families. Comparisons were made with noninstitutionalized children adopted from Romania and with nondeprived within-U.K. adoptees placed before the age of 6 months. Specifically, the validity of the assessment, the degree of continuity and change in levels of functioning from 6 to 11 years, and the factors in the pre- and postadoption environment accounting for heterogeneity in outcome were examined. Pervasive impairment was significantly raised in children experiencing institutional deprivation for ≥6 months of life, with a minority within this group showing no impairment. There was no additional significant effect of duration of deprivation beyond the 6-month cutoff, and few other predictors explained outcome. The pattern of normality/impairment was mainly established by 6 years of age, with considerable continuity at the individual level between 6 and 11 years. The findings are discussed in terms of the possibility of a sensitive period for development. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
7.
This article reports research intended to assess and extend a recent theory of peer responses to low-performing team members (J. A. LePine & L. Van Dyne, 2001a). An instrument that assesses 4 types of peer responses to low performers (compensating for, training, motivating, and rejecting) was developed and then cross-validated in a subsequent study. Results of the study supported the validity of the peer responses measure and were generally consistent with the attributional theory of peer responses. Low-performer characteristics influenced the peer responses. These effects were mediated in part by peer attributions, affect, and cognitions, which explained variance in the peer responses over and above the variance explained by respondents' personality characteristics (i.e., The Big Five). (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
8.
9.
10.
The influence of fibrin glue on adhesion formation and peritoneal healing is evaluated in a prospective, randomized, controlled study. In all, 20 Wistar rats underwent microsurgical suturing of two silicone sheets, one covered with a fibrin glue barrier, to the anterior peritoneum. Each animal thus served as its own control. After 10 days, adhesions and peritoneal healing were evaluated by a blinded observer through a second-look laparotomy. Adhesions were scored using a modification of the classification of Diamond. Tissue around the silicone sheet was examined histologically and by scanning electron microscopy to evaluate the inflammatory reaction and peritoneal healing (ingrowth of blood vessels and quality of peritoneal cells). Adhesion scores for treated and control sides were (mean +/- SD) 2.89 +/- 4.68 and 6.79 +/- 9.09 (P = 0.181) respectively, and the percentage of the sheet covered by peritoneum was 26.25 +/- 31.50 and 29.21 +/- 40.21 (P = 0.226) respectively. Using the paired Wilcoxon rank test, the P values for the ingrowth of blood vessels and peritoneal healing evaluated by histology and scanning electron microscopy were 0.842, 0.692 and 0.695 respectively. We conclude that although the mean adhesion score was reduced by > 50% by fibrin glue, there is no statistically significant difference concerning adhesion formation or peritoneal healing with the use of fibrin glue.  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