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   114746篇
  免费   2686篇
  国内免费   436篇
电工技术   989篇
综合类   2333篇
化学工业   17565篇
金属工艺   5339篇
机械仪表   3685篇
建筑科学   3035篇
矿业工程   625篇
能源动力   1629篇
轻工业   8754篇
水利工程   1542篇
石油天然气   459篇
武器工业   5篇
无线电   10322篇
一般工业技术   21411篇
冶金工业   10691篇
原子能技术   373篇
自动化技术   29111篇
  2024年   78篇
  2023年   288篇
  2022年   303篇
  2021年   761篇
  2020年   656篇
  2019年   749篇
  2018年   15432篇
  2017年   14337篇
  2016年   11114篇
  2015年   1622篇
  2014年   1435篇
  2013年   2753篇
  2012年   4956篇
  2011年   10863篇
  2010年   9522篇
  2009年   6669篇
  2008年   7855篇
  2007年   8770篇
  2006年   894篇
  2005年   1867篇
  2004年   1747篇
  2003年   1716篇
  2002年   1079篇
  2001年   503篇
  2000年   558篇
  1999年   489篇
  1998年   2411篇
  1997年   1643篇
  1996年   1075篇
  1995年   629篇
  1994年   484篇
  1993年   573篇
  1992年   217篇
  1991年   230篇
  1990年   156篇
  1989年   160篇
  1988年   181篇
  1987年   141篇
  1986年   125篇
  1985年   144篇
  1984年   129篇
  1983年   97篇
  1982年   130篇
  1981年   148篇
  1980年   156篇
  1979年   79篇
  1978年   81篇
  1977年   280篇
  1976年   622篇
  1954年   68篇
排序方式: 共有10000条查询结果,搜索用时 9 毫秒
71.
A dozen CuO samples prepared under various conditions and from different starting materials were evaluated as cathode materials for a primary Li/CuO cell. The “thin electrode” method was used for rapid evaluation of the samples. Both coulombic efficiency and discharge voltage depend considerably on the method of synthesis. No correlation was found between the specific surface area and the resistivity of the samples on the one hand and the cathode performance on the other. Best results were obtained from CuO prepared by the oxidation of Cu2O under controlled temperature and time of oxidation.  相似文献   
72.
73.
74.
75.
The Vesilind settling velocity function forms the basis of flux theory used both in state point analysis (for design and capacity rating) and one-dimensional dynamic models (for dynamic process modelling). This paper proposes new methods to address known shortcomings of these methods, based on an extensive set of batch settling tests conducted at different scales. The experimental method to determine the Vesilind parameters from a series of bench scale settling tests is reviewed. It is confirmed that settling cylinders must be slowly stirred in order to represent settling performance of full scale plants for the whole range of solids concentrations. Two new methods to extract the Vesilind parameters from settling test series are proposed and tested against the traditional manual method. Finally, the same data set is used to propose an extension to one-dimensional (1-D) dynamic settler models to account for compression settling. Using the modified empirical function, the model is able to describe the batch settling interface independently of the number of layers.  相似文献   
76.
A new analytical method has been developed for the determination of the reactive lysine content of soya bean protein. The method is based on the reaction of the free basic groups of the protein with 1-phenylazo-2 naphthol-6,8 disulphonic acid. With regard to the stoichiometry of the procedure, it has been proved, contrary to earlier reports, that the basic amino acids, histidine, arginine and lysine, each combine with one mole of the dye. After acylation with propionic anhydride lysine alone loses its dye reactivity. The usefulness of the proposed method has been demonstrated by the determination of the reactive lysine content of several untreated, heat-treated and acid-treated soya bean samples. The results show that heat damage of about 5% in reactive lysine content can be measured in 1·5 h with good reproducibility.  相似文献   
77.
78.
Discusses the theoretical and clinical applications of the postmodern paradigm of social constructionism as a basis for counseling culturally different clients. Such applications avoid the trap of perpetuating the status-quo when working with minority and marginalized clientele. The main points of multiculturalism and social constructionism are summarized, and issues of mutual concern to both perspectives are examined. Applications to psychotherapy are explored, and the challenges of applying the social constructionist approach to culturally competent counseling are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
79.
80.
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