全文获取类型
收费全文 | 36076篇 |
免费 | 1371篇 |
国内免费 | 1107篇 |
专业分类
电工技术 | 1333篇 |
技术理论 | 1篇 |
综合类 | 1808篇 |
化学工业 | 6876篇 |
金属工艺 | 4191篇 |
机械仪表 | 1707篇 |
建筑科学 | 886篇 |
矿业工程 | 388篇 |
能源动力 | 1219篇 |
轻工业 | 1408篇 |
水利工程 | 109篇 |
石油天然气 | 698篇 |
武器工业 | 221篇 |
无线电 | 3876篇 |
一般工业技术 | 5573篇 |
冶金工业 | 760篇 |
原子能技术 | 621篇 |
自动化技术 | 6879篇 |
出版年
2024年 | 65篇 |
2023年 | 298篇 |
2022年 | 534篇 |
2021年 | 623篇 |
2020年 | 499篇 |
2019年 | 492篇 |
2018年 | 469篇 |
2017年 | 687篇 |
2016年 | 937篇 |
2015年 | 1186篇 |
2014年 | 1845篇 |
2013年 | 1745篇 |
2012年 | 1966篇 |
2011年 | 3493篇 |
2010年 | 2786篇 |
2009年 | 2971篇 |
2008年 | 2576篇 |
2007年 | 2665篇 |
2006年 | 2290篇 |
2005年 | 1982篇 |
2004年 | 1732篇 |
2003年 | 1726篇 |
2002年 | 1471篇 |
2001年 | 764篇 |
2000年 | 613篇 |
1999年 | 489篇 |
1998年 | 348篇 |
1997年 | 305篇 |
1996年 | 204篇 |
1995年 | 138篇 |
1994年 | 125篇 |
1993年 | 108篇 |
1992年 | 94篇 |
1991年 | 61篇 |
1990年 | 56篇 |
1989年 | 47篇 |
1988年 | 25篇 |
1987年 | 20篇 |
1986年 | 22篇 |
1985年 | 24篇 |
1984年 | 17篇 |
1983年 | 9篇 |
1982年 | 8篇 |
1981年 | 5篇 |
1980年 | 9篇 |
1979年 | 6篇 |
1977年 | 5篇 |
1959年 | 2篇 |
1957年 | 1篇 |
1951年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
41.
42.
M. Hara Y. Hatano T. Abe K. Watanabe T. Naitoh S. Ikeno Y. Honda 《Journal of Nuclear Materials》2003,320(3):265-271
To improve the durability of hydrogen storage materials against surface poisoning by impurity gases, effectiveness of Pd-coating layer prepared by using a Barrel-Sputtering System was examined for ZrNi powder. The effectiveness of Pd-coating was evaluated by activation temperature, at which Pd/ZrNi poisoned by air could be activated to absorb hydrogen. Characterization of Pd-coated ZrNi (denoted as Pd/ZrNi) by scanning electron microscopy, electron probe microanalysis and X-ray diffraction showed that a uniform Pd-coating layer was formed with the barrel-sputtering system. It was found that the poisoned Pd/ZrNi sample could be activated even at 423 K to absorb hydrogen at room temperature. This exhibits remarkable contrast to bare ZrNi, which could be only activated appreciably above 1073 K. It is concluded that the Pd-coating by barrel sputtering is quite effective to avoid the effect of surface poisoning of powdery hydrogen storage materials. However, the activation at excessively high temperature resulted in the loss of high activity to absorb hydrogen. It was concluded that this phenomenon was associated with reactions between Pd and ZrNi to form PdZr and other byproducts. 相似文献
43.
The GILDES computer model, incorporating Stumm's concept of proton- and ligand-promoted dissolution, has been used to simulate the exposure of copper at room temperature to 210 ppb sulfur dioxide and 80% relative humidity. The agreement is good between the calculations and laboratory exposures performed under these exposure conditions. Surface reactions are relatively more important at lower relative humidities and the dominant corrosion products formed are solid state Cu2SO3, CuSO3 and Cu2U. Free-radical redox processes are important participants and control the relative distribution of Cu(I)- and Cu(H)-containing corrosion products. 相似文献
44.
45.
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
46.
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
47.
48.
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
49.
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
50.
多任务调度算法在单片机控制系统中的应用 总被引:1,自引:1,他引:0
为了满足单片机控制系统的复杂要求 ,提出了多任务调度算法 ,通过与单任务程序结构的对比和分析 ,详细说明了多任务调度算法的实现 ,指出了应用该算法的必要性 ,并且以科研生产的实例说明其具体应用。 相似文献