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   2762篇
  免费   143篇
  国内免费   77篇
电工技术   160篇
技术理论   1篇
综合类   236篇
化学工业   192篇
金属工艺   11篇
机械仪表   36篇
建筑科学   259篇
矿业工程   74篇
能源动力   191篇
轻工业   110篇
水利工程   41篇
石油天然气   46篇
武器工业   3篇
无线电   110篇
一般工业技术   139篇
冶金工业   960篇
原子能技术   14篇
自动化技术   399篇
  2024年   7篇
  2023年   23篇
  2022年   44篇
  2021年   51篇
  2020年   44篇
  2019年   38篇
  2018年   52篇
  2017年   51篇
  2016年   60篇
  2015年   55篇
  2014年   86篇
  2013年   131篇
  2012年   73篇
  2011年   169篇
  2010年   147篇
  2009年   164篇
  2008年   150篇
  2007年   184篇
  2006年   196篇
  2005年   184篇
  2004年   171篇
  2003年   167篇
  2002年   130篇
  2001年   84篇
  2000年   40篇
  1999年   56篇
  1998年   48篇
  1997年   30篇
  1996年   26篇
  1995年   21篇
  1994年   21篇
  1993年   17篇
  1992年   18篇
  1991年   10篇
  1990年   15篇
  1989年   15篇
  1988年   19篇
  1987年   10篇
  1985年   13篇
  1984年   12篇
  1983年   10篇
  1982年   16篇
  1981年   7篇
  1979年   7篇
  1978年   7篇
  1966年   8篇
  1965年   8篇
  1963年   9篇
  1961年   7篇
  1955年   7篇
排序方式: 共有2982条查询结果,搜索用时 31 毫秒
1.
With the emergence of distributed ledger technology (DLT), numerous practitioners and researchers have proclaimed its beneficial impact on supply chain transactions in the future. However, the vast majority of DLT initiatives are discontinued after a short period. With the full potential of DLT laying far down the road, especially managers in supply chain management (SCM) seek for short-term cost-saving effects of DLT in order to achieve long-term benefits of DLT in the future. However, the extant research has bypassed grounding long-term as well as short-term effects of DLT on supply chain transaction with empirical data. We address this shortcoming, following an abductive research approach and combining empirical data from a multiple case study design with the corresponding literature. Our study reveals that the effects of DLT on supply chain transactions are two-sided. We found six effects of DLT solutions that have a cost-reducing or cost avoidance impact on supply chain transactions. In addition, we found two effects that change the power distribution between buyers and suppliers in transactions and a single effect that reduces the dependency of supply chain transactions on third parties. While cost-reducing and avoidance as well as dependency-reducing effects are positive effects, the change in power distribution might come with disadvantages. With these findings, the paper provides the first empirical evidence of the impact of DLT on supply chain transactions, which will enable managers to improve their assessment of DLT usage in supply chains.  相似文献   
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.
试论循环水装置的经济性及其成本分析   总被引:2,自引:1,他引:1  
通过对循环水装置的投资和成本分析,阐述了建设该装置的经济性和社会意义。  相似文献   
4.
大乘资氮集团有限公司狠抓管理和科技,使企业由经营型向效益型转变,同时加速了企业经济增长方式的转变。  相似文献   
5.
Agglomeration and networks in spatial economies   总被引:1,自引:0,他引:1  
We consider the parallel developments in the economics of agglomeration and the economics of networks. We explore the complementarities between the productivity benefits of agglomeration and those of network linkages, arguing that networks of actors dispersed over space may substitute for agglomerations of actors at a single point.JEL Classification: D20, L14, R30  相似文献   
6.
Reviews the book, L'insomnie: Traitement comportemental by Robert Ladouceur and Yves Gros-Louis (1984). The work offers a prospect broader than the medical vision which traditionally dominates the treatment of insomnia. More specifically, the work is articulated around two chapters. The first locates the relative source data of insomnia, and provides the criteria for a precise diagnosis, establishing a clear distinction between primary insomnia and secondary insomnia, and methods generally utilized to measure sleep. As for the second chapter, it is centered on the behavioral methods of treatment of insomnia. According to the authors, any treatment must be preceded by factual information on insomnia, to facilitate the application of the chosen method. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
7.
On the basis of the behavioral approach system (BAS) dysregulation theory of bipolar disorder, this study examined the relation between occurrence of a BAS activation-relevant life event--goal striving--and onset of hypomanic and depressive episodes and symptoms. In particular, the authors examined the relation between preparing for and completing final exams (a goal-striving event) and onset of bipolar spectrum episodes and symptoms in college students with bipolar II disorder or cyclothymia (i.e., "soft" bipolar spectrum conditions). One hundred fifty-nine individuals with either a bipolar spectrum disorder (n=68) or no major affective psychopathology (controls; n=91) were further classified on the basis of whether they were college students (i.e., completed final exams). Consistent with the BAS dysregulation theory, preparing for and completing final exams was associated with an increase in hypomanic but not depressive episodes and symptoms in individuals with a soft bipolar spectrum diagnosis. Furthermore, self-reported BAS sensitivity moderated the presence of certain hypomanic symptoms during final exams. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
8.
We prove NP-completeness of deciding the existence of an economic equilibrium in so-called house allocation markets. House allocation markets are markets with indivisible goods in which every agent holds exactly one copy of some good.  相似文献   
9.
Hispanic children are the fastest growing segment of the population. Numerous factors place them at-risk for school success. This study examined the effects of Child-Centered Play Therapy (CCPT) compared to a curriculum-based small group intervention with 29 Hispanic children referred for school counseling due to behavior problems. Children were assigned to treatment groups by random drawing within grade levels. Treatment was provided by Hispanic bilingual counselors. Statistical analysis revealed that, according to parent report, children receiving CCPT showed statistically significant decreases in externalizing behavior problems, compared to the curriculum-based treatment group. Effect size calculations revealed that CCPT demonstrated a large treatment effect on externalizing behavior problems and a moderate treatment effect on internalizing behavior problems. Cultural considerations and recommendations for practice and future research are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
10.
张燕 《福建建筑》2007,(9):97-98
本文主要从经济角度分析净水厂实际生产情况及经济技术指标等方面的数据。阐述福州西区水厂一期滤池由原先双阀滤池改造成V型滤池的经济性。  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