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   176106篇
  免费   16287篇
  国内免费   8865篇
电工技术   12353篇
技术理论   10篇
综合类   12665篇
化学工业   28309篇
金属工艺   10011篇
机械仪表   11386篇
建筑科学   14660篇
矿业工程   4963篇
能源动力   5248篇
轻工业   12134篇
水利工程   3557篇
石油天然气   9703篇
武器工业   1561篇
无线电   20658篇
一般工业技术   20456篇
冶金工业   7328篇
原子能技术   2091篇
自动化技术   24165篇
  2024年   738篇
  2023年   2833篇
  2022年   5233篇
  2021年   7561篇
  2020年   5681篇
  2019年   4630篇
  2018年   4933篇
  2017年   5700篇
  2016年   5033篇
  2015年   7171篇
  2014年   8826篇
  2013年   10463篇
  2012年   11934篇
  2011年   12676篇
  2010年   11198篇
  2009年   10830篇
  2008年   10677篇
  2007年   9889篇
  2006年   9922篇
  2005年   8388篇
  2004年   5840篇
  2003年   5088篇
  2002年   5181篇
  2001年   4666篇
  2000年   4329篇
  1999年   4106篇
  1998年   3275篇
  1997年   2769篇
  1996年   2498篇
  1995年   2142篇
  1994年   1717篇
  1993年   1222篇
  1992年   1011篇
  1991年   775篇
  1990年   562篇
  1989年   505篇
  1988年   396篇
  1987年   274篇
  1986年   167篇
  1985年   108篇
  1984年   68篇
  1983年   44篇
  1982年   71篇
  1981年   45篇
  1980年   44篇
  1979年   16篇
  1978年   3篇
  1965年   3篇
  1959年   9篇
  1951年   6篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
32.
唐英,清代沈阳人,隶属汉军正白旗。《陶人心语》是清代督陶官唐英撰写的诗集。该诗集内容丰富,表达了唐英对皇帝的感恩之情,以及他的赤城之心;对制陶事业的热爱之情;对亲人的思念关爱之情,体恤百姓的疾苦,关心百姓等。此书具有丰富的文学价值和历史价值。  相似文献   
33.
Qin  Yi  Tao  Xianping  Huang  Yu    Jian 《World Wide Web》2019,22(1):1-37
World Wide Web - Rule mechanism has been widely used in many areas, such as databases, artificial intelligent and pervasive computing. In a rule mechanism, rule activation decides which rules are...  相似文献   
34.
本项目主要研究和实现了工业废白土在BAYAH燃煤自备电厂中的再利用,实现变废为宝,减少了环境污染,同时为企业创造了一定的经济效益。针对废白土的特性,对燃料输送系统给煤机、皮带机、煤仓、下料溜子和排渣系统进行了改造。通过修改操作规程消除废白土对锅炉运行的影响。  相似文献   
35.
To overcome the drawbacks of solid microporous materials for CO2 capture, this proof‐of‐concept study demonstrates a low‐cost and rapid method for producing composites consisting of hypercrosslinked polymers (HCP) with a polyethyleneimine (PEI) binder. The resulting materials capture CO2 through physical and chemical absorption simultaneously. Compared with HCP, the composites exhibit higher CO2 uptake, higher volumetric density, and improved tolerance to water which is attributed to the PEI binder.  相似文献   
36.
37.
Parameter estimation plays an important role in the field of system control. This article is concerned with the parameter estimation methods for multivariable systems in the state-space form. For the sake of solving the identification complexity caused by a large number of parameters in multivariable systems, we decompose the original multivariable system into some subsystems containing fewer parameters and study identification algorithms to estimate the parameters of each subsystem. By taking the maximum likelihood criterion function as the fitness function of the differential evolution algorithm, we present a maximum likelihood-based differential evolution (ML-DE) algorithm for parameter estimation. To improve the parameter estimation accuracy, we introduce the adaptive mutation factor and the adaptive crossover factor into the ML-DE algorithm and propose a maximum likelihood-based adaptive differential evolution algorithm. The simulation study indicates the efficiency of the proposed algorithms.  相似文献   
38.
39.
In the future, hydrogen will be an important energy carrier and industrial raw material. Catalytic steam reforming of bio-oils is a promising and economically viable technology for hydrogen production. However, during the reforming process, the catalysts are rapidly deactivated due to coke formation and sintering. Thus, maintaining the activity and stability of catalysts is the key issue in this process. Optimized operation conditions could extend the catalyst lifetime by affecting the coke morphology or promoting coke gasification. This article summarizes the recent developments in the field of catalytic steam reforming of bio-oils, focusing on the operation conditions, the properties of the catalysts, and the effects of the catalyst supports. The expected insights into the catalytic steam reforming of bio-oils will provide further guidance for hydrogen production from bio-oils.  相似文献   
40.
Abstract

Different drying methods (spray drying (SD), vacuum drying (VD), microwave vacuum drying (MVD), and infrared vacuum drying (IFVD)) were applied in order to compare the hygroscopicity behavior of chicken powders. The hygroscopicity curves and glass transition temperature were used to evaluate the influence of ambient humidity and temperature on moisture absorption of powders. The results showed that the chicken powder dried by MVD had the lowest moisture absorption, followed by IFVD, VD, and SD. The hygroscopicity of SD chicken powders was different from other three kinds of chicken powders due to the physical properties of particles and the changes of protein secondary structure as detected by the Fourier transform-infrared spectrometer. For the three vacuum drying methods, the difference of protein secondary structure was the main reason of differences in hygroscopicity. Although MVD chicken powders were slightly inferior to SD chicken powders in taste, MVD chicken powders were the best in terms of smell and color as suggested by instrumental sensory parameter evaluations. It was found that MVD had a positive effect on reducing moisture absorption and maintaining sensory quality of chicken powders.  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