全文获取类型
收费全文 | 40447篇 |
免费 | 4010篇 |
国内免费 | 2921篇 |
专业分类
电工技术 | 1789篇 |
综合类 | 3662篇 |
化学工业 | 6267篇 |
金属工艺 | 2137篇 |
机械仪表 | 1653篇 |
建筑科学 | 4760篇 |
矿业工程 | 1812篇 |
能源动力 | 1606篇 |
轻工业 | 3161篇 |
水利工程 | 1373篇 |
石油天然气 | 2242篇 |
武器工业 | 436篇 |
无线电 | 5143篇 |
一般工业技术 | 6326篇 |
冶金工业 | 2128篇 |
原子能技术 | 946篇 |
自动化技术 | 1937篇 |
出版年
2024年 | 197篇 |
2023年 | 688篇 |
2022年 | 1183篇 |
2021年 | 1406篇 |
2020年 | 1463篇 |
2019年 | 1363篇 |
2018年 | 1175篇 |
2017年 | 1528篇 |
2016年 | 1485篇 |
2015年 | 1554篇 |
2014年 | 2279篇 |
2013年 | 2434篇 |
2012年 | 2693篇 |
2011年 | 2926篇 |
2010年 | 2237篇 |
2009年 | 2332篇 |
2008年 | 2174篇 |
2007年 | 2614篇 |
2006年 | 2409篇 |
2005年 | 1986篇 |
2004年 | 1704篇 |
2003年 | 1515篇 |
2002年 | 1330篇 |
2001年 | 1043篇 |
2000年 | 976篇 |
1999年 | 764篇 |
1998年 | 612篇 |
1997年 | 578篇 |
1996年 | 482篇 |
1995年 | 413篇 |
1994年 | 358篇 |
1993年 | 300篇 |
1992年 | 232篇 |
1991年 | 199篇 |
1990年 | 167篇 |
1989年 | 138篇 |
1988年 | 100篇 |
1987年 | 66篇 |
1986年 | 45篇 |
1985年 | 32篇 |
1984年 | 36篇 |
1983年 | 23篇 |
1982年 | 22篇 |
1981年 | 12篇 |
1980年 | 18篇 |
1979年 | 22篇 |
1965年 | 5篇 |
1963年 | 5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
61.
62.
63.
Urcuioli Peter J.; Vu Kim-Phuong L.; Proctor Robert W. 《Canadian Metallurgical Quarterly》2005,134(1):93
Pigeons pecked left versus right keys contingent upon the color presented at 1 of those locations. Spatial-response latencies were shorter when the color appeared at the same location as the required response than at the opposite location. This Simon effect occurred when the stimulus on the alternative key was constant, varied from trial to trial, or changed when the color cue appeared and when the reinforcement probability for correct responses was the same on corresponding as on noncorresponding trials. Humans performing the same task by touching the keys also showed the Simon effect. These findings demonstrate that for pigeons, too, a relevant symbolic cue activates a spatial code that produces faster responses at the location corresponding with the activated code. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
64.
CeO2和La2O3对高炉喷吹煤粉燃烧过程的影响 总被引:12,自引:0,他引:12
在模拟高炉喷吹的条件下,对添加CeO2 和La2O3的混合煤粉进行了燃烧试验,考察了稀土氧化物对高炉喷吹煤粉燃烧过程的影响,并探讨了其助燃作用机理. 相似文献
65.
66.
A new analytical method is proposed for the analysis of boundary effect in a pipe bend portion loaded by bending moment combined
with internal pressure. The proposed method is based on the simplifying hypotheses, which make possible to represent all deformation-
and force-related parameters in terms of the tangential displacement assumed in the form of the Fourier series expansion by
the circumferential coordinate. A set of quadric differential equations by axial coordinate containing unknown displacement
expansion coefficients is derived. We obtained an analytical approximate solution for a pipe bend portion and precise solution
for a straight pipe, which are expressed via Krylov functions. We formulate the application procedure for the method of initial
parameter, where the values of tangential and longitudinal displacements, axial and tangential forces are used as boundary
conditions. We present the equations relating the above-mentioned parameters in the initial and end sections of the pipe bend
portion. The results obtained are compared with the available published data.
__________
Translated from Problemy Prochnosti, No. 4, pp. 64 – 94, July – August, 2005. 相似文献
67.
R.C. Picu G. Vincze F. Ozturk J.J. Gracio F. Barlat A.M. Maniatty 《Materials Science and Engineering: A》2005,390(1-2):334-343
The mechanical behavior of the commercial aluminum alloy AA5182-O is investigated at temperatures ranging from −120 to 150 °C and strain rates from 10−6 to 10−1 s−1. The strain rate sensitivity parameter is determined as a function of temperature and plastic strain, and the strain rate and temperature range in which dynamic strain aging leads to negative strain rate sensitivity is mapped. The effect of dynamic strain aging on ductility and strain hardening is investigated. The sensitivity of the measured quantities to the experimental method employed and their dependence on grain shape are discussed. The experimental data are compared with the predictions of a model constructed based on a recently proposed mechanism for dynamic strain ageing. The mechanism is based on the effect solute clustering at forest dislocations has on the strength of dislocation junctions. The model is shown to reproduce qualitatively the experimental trends. 相似文献
68.
69.
辐射的低剂量生物效应及分子流行病学研究现状 总被引:2,自引:0,他引:2
对低剂量辐射效应研究中的主要问题,诸如线性无阈假设、辐射致癌危险评价、辐射致癌机理以及辐射旁效应进行了综述,并概要介绍了分子流行病学在辐射效应研究中的应用及其研究现状。 相似文献
70.
An inherent self-heating effect of the silicon-on-insulator (SOI) devices limits their application at high current Ievels. In this paper a novel solution to reduce the self-heating effect is proposed, based on N+ and O+ co-implantation into silicon wafer to form a new buried layer structure. This new structure was simulated using Medici program, and the temperature distnbution and output characteristics were compared with those of the conven-tional SOI counterparts. As expected, a reduction of self-heating effect in the novel SOI device was observed. 相似文献