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   38522篇
  免费   4246篇
  国内免费   2339篇
电工技术   6193篇
技术理论   2篇
综合类   2939篇
化学工业   1539篇
金属工艺   842篇
机械仪表   2970篇
建筑科学   4049篇
矿业工程   2715篇
能源动力   957篇
轻工业   1158篇
水利工程   3239篇
石油天然气   1005篇
武器工业   260篇
无线电   4081篇
一般工业技术   1797篇
冶金工业   758篇
原子能技术   539篇
自动化技术   10064篇
  2024年   148篇
  2023年   490篇
  2022年   1057篇
  2021年   1306篇
  2020年   1314篇
  2019年   937篇
  2018年   857篇
  2017年   1201篇
  2016年   1478篇
  2015年   1797篇
  2014年   3038篇
  2013年   2652篇
  2012年   3778篇
  2011年   3663篇
  2010年   2467篇
  2009年   2405篇
  2008年   2306篇
  2007年   2575篇
  2006年   2217篇
  2005年   2025篇
  2004年   1704篇
  2003年   1326篇
  2002年   988篇
  2001年   684篇
  2000年   608篇
  1999年   427篇
  1998年   329篇
  1997年   286篇
  1996年   239篇
  1995年   204篇
  1994年   152篇
  1993年   95篇
  1992年   71篇
  1991年   58篇
  1990年   39篇
  1989年   37篇
  1988年   41篇
  1987年   10篇
  1986年   14篇
  1985年   11篇
  1984年   9篇
  1983年   14篇
  1982年   13篇
  1981年   10篇
  1980年   8篇
  1979年   5篇
  1977年   3篇
  1975年   2篇
  1963年   2篇
  1951年   2篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
何虎 《西北水电》2006,(2):57-59
系统地介绍了SSJ-3060计算机监控系统,说明了系统的结构、功能、特点,并着重介绍了该系统在宝珠寺电站运行情况及使用效果。  相似文献   
102.
The authors investigated relationships between marijuana and inhalant use and several cultural and demographic factors in Anglo American and Hispanic American adolescents (N=1,094). Outcome measures assessed lifetime and 30-day marijuana and inhalant use. Predictors and covariates used in logistic regression analyses were region, grade, gender, knowledge, acculturation, familism, and parental monitoring. Hispanic Americans exhibited higher usage across all measures. In this group, high acculturation was associated with low marijuana, but high inhalant, use. Across all participants, positive family relations and parental monitoring were strongly associated with attenuated marijuana use hut only among those most knowledgeable about drugs. Familism and monitoring were not associated with diminished usage among the less knowledgeable. For inhalants, monitoring combined with high knowledge or high familism was associated with diminished usage. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
103.
This paper describes the implementation and experimental studies of an adaptive self-optimizing pole shifting power system stabilizer. Using an Intel iSBC386/21 single-board computer, the adaptive power system stabilizer has been tested on a physical model of a single-machine infinite-bus power system. Under different operating conditions and disturbances, the behavior of the proposed adaptive stabilizer was investigated. Comparison has also been made to a digital-type conventional fixed-parameter power system stabilizer. Results of the experimental studies show that the proposed adaptive stabilizer outperforms the conventional stabilizer.  相似文献   
104.
较详细地介绍了在北京核电厂模拟培训中心的模拟器上建立RMS仿真系统的工作。首先对仿真的原型进行分析和简化,建立数学物理模型,并对包括RCS、PZR、SG、CVCS等的近20个核电厂系统进行了动态仿真建模,确定RMS各监测点放射性水平仿真读数的计算方法,最后,给出部分仿真实验结果,以验证数学物理模型的可靠性和适用性。  相似文献   
105.
海洋是个特殊的环境,为许多光纤传感器提供了一个极好的应用领域。对于海洋这个特殊的“敌对”环境,光纤传感器将面临许多挑战。 本文着重介绍应用于海水温度、浊度、盐份浓度、浮游生物和溶解物光吸收量以及环境湿度等海洋环境参数监测的光纤传感器的原理、结构和特性,展望光纤传感器在海洋环境监测方面的美好前景。  相似文献   
106.
Reflectance anisotropy spectroscopy (RAS) has been used to study As-by-P exchange during metalorganic vapor phase epitaxy. The study focuses on the processes occurring during switching from GaAs to GaInP, especially the effect of purging PH3 over a GaAs surface. GaAsP/GaAs superlattices of different periodicity were grown and the P-content was determined by high-resolution x-ray diffraction and correlated to the RAS spectra. From the temperature dependence of the P-content, an activation energy of 0.56 eV was estimated for the incorporation mechanism. In addition to the insights into the processes at mixed group-V heterointerfaces, our study demonstrates the reproducibility of RAS transients that thus can be used for process monitoring.  相似文献   
107.
通过对几座典型水库大坝原型观测设施的分析论证,总结了土坝测压管观测设备分析论证的步骤和方法,从观测设施的考证及全面性、合理性、可靠性等方面进行分析,以确定各测压管的可操作性,从而为观测资料的准确性以及整编分析提供可靠的保证。  相似文献   
108.
In this paper, we introduce the LOPOCOS (Low Power Co-synthesis) system, a prototype CAD tool for system level co-design. LOPOCOS targets the design of energy-efficient embedded systems implemented as heterogeneous distributed architectures. In particular, it is designed to solve the specific problems involved in architectures that include dynamic voltage scalable (DVS) processors. The aim of this paper is to demonstrate how LOPOCOS can support the system designer in identifying energy-efficient hardware/software implementations for the desired embedded systems. Hence, highlighting the necessary optimization steps during design space exploration for DVS enable architectures. The optimization steps carried out in LOPOCOS involve component allocation and task/communication mapping as well as scheduling and dynamic voltage scaling. LOPOCOS has the following key features, which contribute to this energy efficiency. During the voltage scaling valuable power profile information of task execution is taken into account, hence, the accuracy of the energy estimation is improved. A combined optimization for scheduling and communication mapping based on genetic algorithm, optimizes simultaneously execution order and communication mapping towards the utilization of the DVS processors and timing behaviour. Furthermore, a separation of task and communication mapping allows a more effective implementation of both task and communication mapping optimizationsteps. Extensive experiments are conducted to demonstrate the efficiency of LOPOCOS. We report up to 38% higher energy reductions compared to previous co-synthesis techniques for DVS systems. The investigations include a real-life example of an optical flow detection algorithm.  相似文献   
109.
结合紫金苑工程实例,分析喷锚结合水泥搅拌桩在基坑支护中的应用并总结施工、监测经验。  相似文献   
110.
Determining contributions of source-monitoring and inhibitory function to age-related forgetting has been an elusive goal for cognitive theorists. Five studies used a verbal working memory paradigm to examine mechanisms accounting for disproportionate retroactive interference (RI) experienced with adult aging. Participants distinguished studied target-word pairs from interfering pairs that were read aloud. Source-monitoring and inhibitory task components varied through manipulations of response requirements. RI effects were primarily due to source-monitoring failures rather than to inhibitory failures. Removing both source and inhibitory components eliminated age differences in RI. When source monitoring was emphasized, RI continued to be observed in all age groups but disproportionately for older adults. Process dissociation analyses of memory found recollection decreases and familiarity increases consistent with source failures. (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