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   5900篇
  免费   49篇
  国内免费   15篇
电工技术   29篇
综合类   15篇
化学工业   327篇
金属工艺   58篇
机械仪表   81篇
建筑科学   85篇
矿业工程   18篇
能源动力   59篇
轻工业   182篇
水利工程   10篇
石油天然气   21篇
武器工业   1篇
无线电   228篇
一般工业技术   332篇
冶金工业   4248篇
原子能技术   23篇
自动化技术   247篇
  2022年   24篇
  2021年   29篇
  2020年   20篇
  2019年   29篇
  2018年   13篇
  2017年   22篇
  2016年   28篇
  2015年   27篇
  2014年   36篇
  2013年   125篇
  2012年   46篇
  2011年   88篇
  2010年   66篇
  2009年   60篇
  2008年   70篇
  2007年   66篇
  2006年   70篇
  2005年   82篇
  2004年   61篇
  2003年   53篇
  2002年   50篇
  2001年   50篇
  2000年   47篇
  1999年   156篇
  1998年   1379篇
  1997年   813篇
  1996年   485篇
  1995年   305篇
  1994年   255篇
  1993年   276篇
  1992年   67篇
  1991年   47篇
  1990年   70篇
  1989年   72篇
  1988年   70篇
  1987年   68篇
  1986年   54篇
  1985年   60篇
  1984年   15篇
  1983年   35篇
  1982年   44篇
  1981年   40篇
  1980年   39篇
  1979年   17篇
  1978年   26篇
  1977年   110篇
  1976年   175篇
  1975年   22篇
  1974年   13篇
  1973年   14篇
排序方式: 共有5964条查询结果,搜索用时 15 毫秒
1.
A hybrid power compensator (HPC) consisting of a static VAr compensator and a dynamic compensator needs to be optimally controlled during the compensation of nonlinear loads. The HPC must be controlled to meet minimum requirements in terms of power factor and harmonic distortion, while at the same time minimizing its total cost. An artificial neural network (ANN) is used to control the HPC amidst a very dynamic power system environment. The performance of a reference ANN is evaluated while controlling an HPC connected to a typical nonlinear industrial load. The training and performance of the ANN is then optimized in terms of training set size, training set packing and ANN topology and the performance compared to the reference ANN. This paper highlights the importance of optimising the mentioned ANN parameters to achieve optimum ANN training and modeling accuracy. The results obtained reveals that the application of an ANN in controlling an HPC is feasible given that the ANN parameters are chosen appropriately.  相似文献   
2.
3.
Gamma delta T-Cells represent a minor subpopulation of T-lymphocytes in man and their role in normal and diseased human skin is unknown. This article is a comprehensive review of T-lymphocytes bearing the gamma delta T-cell receptor in normal and pathological human skin. Firstly, we have documented the occurrence of gamma delta T-cells in normal skin and in a range of reactive and malignant skin conditions. We have then discussed the experimental findings regarding the repertoire used by gamma delta T-cells in normal human skin and in cutaneous disorders with an increased percentage of gamma delta T-cells.  相似文献   
4.
5.
台北101层国际金融中心之结构施工技术与其设计考量概述   总被引:1,自引:0,他引:1  
本文旨在简要说明目前正在施工中之超高层大楼—台北国际金融中心之结构系统、钢结构工程、钢筋混凝土工程基础与深开挖工程等特殊施工技术,并佐以相关之设计考量与施工规划概要,以供工程界做参考。  相似文献   
6.
The results presented in the literature, which attempt to elucidate the mechanisms by which triglyceride oils are bleached by earths, are reviewed. The impact of this work and how the mechanistic proposals affect changes in oil properties are considered, with particular emphasis on the needs of the palm oil processor. Important properties include color, metals and phosphorus content and oxidative stability of the oil. Investigations made in our own laboratories have been aimed at elucidating the effect of varying physical and chemical properties of the bleaching earth on the quality of bleached and deodorized oils. Techniques used in this work are pore-size distribution, surface area, scanning and transmission electron microscopy and a variety of chemical and X-ray analysis methods. The ability to vary such parameters in montmorillonite clays by alteration of process conditions to give materials with specific performance characteristics is demonstrated. Comparisons are made between acid-activated montmorillonites and other clay types.  相似文献   
7.
8.
Comparison evaluation of the methods of treatment was based on the analysis of the results of management of 347 patients with general purulent decompensated peritonitis with polyorganic insufficiency. The efficacy of closed drainage in 98 patients, continuous flow irrigation (dialysis) in 126, stage programmed irrigation and inspection of the abdominal cavity in 99, and open drainage in 24 patients was compared. The causes of peritonitis were: complications after acute surgical diseases (in 156 cases), in planned operations (59), and in obstetrical and gynecological diseases (132). Most of the patients were brought to the clinic from other hospitals because of unsuccessful treatment of peritonitis and absence of means for performing hemodialysis and management of polyorganic insufficiency. The incidence of the last-named reached 71.0 to 91.0% in the different groups of patients. In monotypic complex treatment, stage programmed irrigation was marked by a much lesser number of abscesses and other complications and a lower mortality (20.2%) as compared to flow irrigation (30.0%, closed drainage (27.5%), and open (laparostomy) treatment (37.5%). Despite the very serious contingent of patients, total mortality (27.0%) in the application of the indicated methods was quite low.  相似文献   
9.
BACKGROUND: This study examined patients with a first-episode of affective psychosis during acute and compensated states in order to determine whether changes in attentional functioning over time were accompanied by changes in the severity of psychotic or affective symptoms. METHODS: Attentional performance was measured in patients (n = 27) using the degraded-stimulus continuous Performance Test (CPT) and symptoms were assessed at the time of index hospitalization, and 2 months after discharge. A comparison group of normal volunteers (n = 31) also performed the CPT two months apart. RESULTS: Patients performed significantly worse than controls at the initial testing but not at follow-up. The improvement in attentional performance significantly correlated with decreased severity of manic symptoms. CONCLUSIONS: Results suggest attentional dysfunction is a state-dependent characteristic of mania, and may provide an additional measure of clinical improvement following treatment.  相似文献   
10.
A rare case associated with congenital hematometrocolpos in a circumcised 13 years old Somalian girl is presented. Emphasis on proper history is highlighted. Mutilation caused by bad cultural practice of female circumcision which is although not a problem in Pakistan, is brought into notice for those who may be unaware of perineal appearance of a circumcised female and stitched over vagina.  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