全文获取类型
收费全文 | 41476篇 |
免费 | 1656篇 |
国内免费 | 1228篇 |
专业分类
电工技术 | 1903篇 |
技术理论 | 1篇 |
综合类 | 2108篇 |
化学工业 | 7337篇 |
金属工艺 | 4476篇 |
机械仪表 | 2160篇 |
建筑科学 | 1061篇 |
矿业工程 | 487篇 |
能源动力 | 1333篇 |
轻工业 | 1629篇 |
水利工程 | 129篇 |
石油天然气 | 770篇 |
武器工业 | 268篇 |
无线电 | 4753篇 |
一般工业技术 | 6004篇 |
冶金工业 | 951篇 |
原子能技术 | 823篇 |
自动化技术 | 8167篇 |
出版年
2024年 | 71篇 |
2023年 | 324篇 |
2022年 | 607篇 |
2021年 | 714篇 |
2020年 | 585篇 |
2019年 | 548篇 |
2018年 | 529篇 |
2017年 | 807篇 |
2016年 | 1093篇 |
2015年 | 1378篇 |
2014年 | 2181篇 |
2013年 | 2062篇 |
2012年 | 2346篇 |
2011年 | 4013篇 |
2010年 | 3227篇 |
2009年 | 3464篇 |
2008年 | 2956篇 |
2007年 | 3039篇 |
2006年 | 2641篇 |
2005年 | 2272篇 |
2004年 | 1910篇 |
2003年 | 1910篇 |
2002年 | 1607篇 |
2001年 | 877篇 |
2000年 | 692篇 |
1999年 | 561篇 |
1998年 | 396篇 |
1997年 | 342篇 |
1996年 | 244篇 |
1995年 | 164篇 |
1994年 | 147篇 |
1993年 | 127篇 |
1992年 | 106篇 |
1991年 | 68篇 |
1990年 | 68篇 |
1989年 | 53篇 |
1988年 | 29篇 |
1987年 | 26篇 |
1986年 | 25篇 |
1985年 | 28篇 |
1984年 | 21篇 |
1983年 | 14篇 |
1982年 | 13篇 |
1981年 | 11篇 |
1980年 | 9篇 |
1979年 | 8篇 |
1977年 | 7篇 |
1974年 | 4篇 |
1957年 | 4篇 |
1951年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
61.
It is demonstrated that glassy carbon powder can be thermochemically activated. During activation, a film with open pores is created on the glassy carbon particles. This film has a large internal surface area, which is accessible to liquids and gases. A simple model for the evolution of the internal surface area in glassy carbon powder during thermochemical gas-phase oxidation is also presented and compared with experimental data. Experimental results are in qualitative agreement with the model. We found that a sharp particle size distribution is desirable with regard to potential technical applications. 相似文献
62.
No authorship indicated 《Canadian Metallurgical Quarterly》1992,47(4):479a
The Early Career Awards recognize the large number of excellent young psychologists. Recipients of this award may not have held a PhD for more than nine years. The areas considered in 1991 were animal learning and behavior, developmental, and personality. The winners for 1991 were Kent C. Berridge, Susan A. Gelman, and Randy J. Larsen. For each winner a citation, biography, and selected bibliography of their works are presented. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
63.
64.
65.
66.
67.
Coatings derived from organofunctional silanes have been investigated as possible replacements for the chromate-based systems used in the aerospace industry. In this study, organofunctional silanes [bis-(triethoxysilylpropyl)ethane and bis(triethoxysilylpropyl) tetrasulfide] were reacted with commercially available acrylate (ECO-CRYL™ 9790) and epoxy (EPI-REZ™ WD-510) resins, resulting in a one-step, low-VOC, chromate-free primer. Liquid-state 29Si and 13C NMR were used to determine structural characteristics of various optimized formulations. 相似文献
68.
Ali Hassanzadeh 《Corrosion Science》2007,49(4):1895-1906
In our previous works, the corrosion inhibition properties of propylamine (PA), iso-propylamine (i-PA), butylamine (BA), tert-butylamine (t-BA), hexylamine (HA), ethylenediamine (EDA), diethanolamine (DEA), 3-amino-1-propanol (3-AP), 2-dimethylethanolamine (2-DEA), cyclohexylamine (CHA), N-methylcyclohexylamine (N-MCA) and dicyclohexylamine (DCHA) have been investigated by means of electrochemical impedance spectroscopy (EIS) with a carbon steel rotating disc electrode in some petroleum/water corrosive mixtures containing acetic acid and NaCl at 25 °C. In this work, the Kramers-Kronig transformations (KKTs) were applied to evaluate the validity of the impedance data of these amine compounds in hydrodynamic condition. The results obtained showed that experimental impedance data did not satisfy in K-K relations completely viz. indicated some errors. These errors were related to stray capacitances, external transmission line effects, pits formation and change in interface during data acquisition at high and low frequencies regions. In addition, the selection of a suitable equivalent circuit strongly emphasized to better interpret of EIS data which in turn cause better resulted KKTs spectra. With considering obtained transformations, more effective inhibitor was selected with regard to its charge transfer resistance, the corrosion capacitance and well satisfying in K-K relations. 相似文献
69.
Enhanced C (EC) is a set-oriented, extensible, C-like language. EC uses data abstractions to define new types. These data abstractions, called clusters, are macro-like devices that perform substitution on the typed syntax tree. Debugging programs that use clusters raise problems that are not encountered in ordinary programming languages. At compile time there is a need to determine and report whether the macro expansion will result in a legal program before this expansion actually takes place. At run-time the problems are how to account for replaced statements and how to handle variables whose types have been established by the clusters, variables that disappear, or variables whose names have been changed. This article presents these problems and their solutions as implemented by the EC compiler and the EC symbolic debugger. Similar debugging problems appear in other languages: The need to handle variables at run time is common to all languages that support data abstraction even if the abstractions are procedure oriented; also, a mild form of the problem of the replaced statement appears in inline procedure substitution of Ada. The solutions developed for the EC debugger apply to these cases as well. 相似文献
70.
介绍了图像增强技术中,空间域处理方法中的邻域平均法的原理、算法,及该原理在windows平台上以C++ Builder为开发工具的具体程序实现。 相似文献