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   10945篇
  免费   1213篇
  国内免费   507篇
电工技术   2103篇
技术理论   1篇
综合类   855篇
化学工业   924篇
金属工艺   181篇
机械仪表   382篇
建筑科学   1038篇
矿业工程   342篇
能源动力   729篇
轻工业   686篇
水利工程   2902篇
石油天然气   156篇
武器工业   37篇
无线电   425篇
一般工业技术   370篇
冶金工业   648篇
原子能技术   61篇
自动化技术   825篇
  2024年   92篇
  2023年   287篇
  2022年   512篇
  2021年   578篇
  2020年   434篇
  2019年   389篇
  2018年   373篇
  2017年   419篇
  2016年   406篇
  2015年   421篇
  2014年   654篇
  2013年   570篇
  2012年   722篇
  2011年   791篇
  2010年   561篇
  2009年   599篇
  2008年   568篇
  2007年   671篇
  2006年   597篇
  2005年   500篇
  2004年   434篇
  2003年   376篇
  2002年   283篇
  2001年   289篇
  2000年   185篇
  1999年   168篇
  1998年   125篇
  1997年   123篇
  1996年   84篇
  1995年   88篇
  1994年   94篇
  1993年   60篇
  1992年   50篇
  1991年   36篇
  1990年   37篇
  1989年   34篇
  1988年   19篇
  1987年   8篇
  1986年   4篇
  1985年   3篇
  1984年   2篇
  1983年   3篇
  1982年   3篇
  1980年   4篇
  1977年   1篇
  1976年   2篇
  1975年   1篇
  1966年   1篇
  1958年   1篇
  1951年   1篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
981.
通过对采区内掘进工作面各个时段迎头风量的调控,使采区范围内各用风地点风量分配趋近合理,采区范围内采、掘作业在时间和空间上尽量达到统一,保证矿井安全、正常有序生产。  相似文献   
982.
A pilot plant of biomass pyrolysis using pyrolysis products as fuel has been tested and shown to improve energy balance of the process and to be environmentally friendly by avoiding rejection of pyrolysis pollutants fumes into the atmosphere. The high number of parameters involved in a pyrolysis process makes it difficult to specify an optimum procedure for charcoal yield and pyrolysis cycle durability. So the knowledge of the essential parameters which govern the kinetics mechanisms of the biomass thermal decomposition and the combustion of pyrolysis gases is very useful to understand the operating cycle of the plant. In the present study a thermochemical model is developed in order to simulate and control the operating cycle of the system. The effect of the inlet molar air flow rate on the temporal evolution of biomass mass loss rate and temperatures in the different active zones of the pilot plant as well as the determination of the critical inlet molar air flow rate for which accidental runaway of combustion reactions occurs are presented. To avoid this accidental phenomenon a Proportional-Integral-Derived (PID) anticipated regulation is used in order to control temperatures evolution in the different zones of the device and avoid the runaway of combustion reactions.  相似文献   
983.
In groupware tools, the activation of a function may affect other users who might have conflicting interests. We developed technical mechanisms to support users in resolving them. Contrary to current implementations of groupware tools, these mechanisms strengthen the position of the users who are affected by the activation of said functions. Supporting the visibility of a function's activation, and providing a channel for communication or means to intervene against the function's activation are approaches which constitute a framework to implement these mechanisms. We conclude with showing implementation examples of the framework and their evaluation in the POLITeam project.  相似文献   
984.
本文介绍的数字锁相系统,用于调节激振装置中直流电动机的速度。根据激振装置的要求研制了各控制环节,在频率给定及速度反馈方面具有一定特点,并建立了系统的数学模型。该装置用于工业生产多年,实践表明该系统可获得较高的转速精度。  相似文献   
985.
The differential relations of children's emotion-related regulation (i.e., effortful control and impulsivity) to their personality resiliency, adult-rated popularity, and social competence were examined in children who were 4.5-7.9 years old and who were remeasured 2 years later. Parents and teachers reported on all constructs, and children's attentional persistence was observed. Structural equation modeling was used to test the mediating role of resiliency on the relations between regulation/control and popularity using two-wave longitudinal data. The results provide some evidence of the mediating role of resiliency in the relations between effortful control and popularity, provide some evidence of bidirectional effects, and also buttress the view that emotional regulation should be differentiated into effortful and reactive forms of control. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
986.
Objective: To examine cardiac rehabilitation program (CRP) participants' beliefs about their interventionists (proxy efficacy and reliance), self-efficacy, and exercise behavior during transition to home-based exercise. Participants and Design: Participants were 44 (16 women and 28 men) CRP outpatients (Mage = 59.43 ± 13.53 years). The design was prospective, with proxy efficacy and reliance as well as self-efficacy being used to predict two outcomes: self-regulatory self-efficacy and home-based exercise. Results: After self-regulatory efficacy reported earlier in the program was controlled for, proxy reliance predicted later program self-regulatory efficacy for home-based exercise (adjusted R2 = .10, p = .02). Proxy efficacy for self-regulation predicted home-based exercise frequency (adjusted R2 = .18, p = .01). Greater proxy efficacy for self-regulation was associated with higher exercise frequency. Conclusion: CRP participants' beliefs in the capabilities of their exercise consultants to help them develop self-regulatory skills play a role in how much exercise they do after supervised rehabilitation. Yet, individuals who strongly rely on their interventionists to assist them in exercising report weaker self-efficacy for exercising on their own. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
987.
分析了挠力河流域的自然地理概况及降水、径流和蒸发等水文特性。  相似文献   
988.
黑龙江流域冬季径流特征   总被引:1,自引:1,他引:1  
黑龙江流域地处高纬度。冬季严寒漫长,冻土深,受季风影响径流年内分配极不均匀,了解冬季径流特征,对分析、评估和利用冬季水资源是十分重要的。  相似文献   
989.
PDF文件链接信息提取与修改   总被引:2,自引:0,他引:2  
顾兆军  张俊 《计算机工程》2005,31(Z1):187-188
主要介绍了航空规章采用PDF文件格式,使用了书签、链接功能;利用AdobeAcrobat提供的编程接口编写Plug-in插件,实现了文件内和文件间的链接信息自动生成技术。  相似文献   
990.
In this paper, we will establish a framework that can convert the robust output regulation problem for discrete‐time nonlinear systems into a robust stabilization problem for an appropriately augmented system consisting of the given plant and a specific dynamic system called internal model. We then apply this framework to solve the local robust output regulation problem for a general class of discrete‐time nonlinear systems. The results of this paper gives a discrete‐time counterpart of the recent results on the continuous‐time robust output regulation problem. Copyright © 2005 John Wiley & Sons, Ltd.  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