全文获取类型
收费全文 | 1509篇 |
免费 | 50篇 |
国内免费 | 15篇 |
专业分类
电工技术 | 16篇 |
综合类 | 12篇 |
化学工业 | 340篇 |
金属工艺 | 27篇 |
机械仪表 | 34篇 |
建筑科学 | 78篇 |
矿业工程 | 2篇 |
能源动力 | 27篇 |
轻工业 | 118篇 |
水利工程 | 10篇 |
石油天然气 | 9篇 |
无线电 | 163篇 |
一般工业技术 | 228篇 |
冶金工业 | 358篇 |
原子能技术 | 7篇 |
自动化技术 | 145篇 |
出版年
2023年 | 8篇 |
2022年 | 23篇 |
2021年 | 17篇 |
2020年 | 22篇 |
2019年 | 18篇 |
2018年 | 17篇 |
2017年 | 21篇 |
2016年 | 47篇 |
2015年 | 31篇 |
2014年 | 46篇 |
2013年 | 69篇 |
2012年 | 62篇 |
2011年 | 56篇 |
2010年 | 46篇 |
2009年 | 43篇 |
2008年 | 56篇 |
2007年 | 48篇 |
2006年 | 54篇 |
2005年 | 46篇 |
2004年 | 45篇 |
2003年 | 34篇 |
2002年 | 36篇 |
2001年 | 31篇 |
2000年 | 25篇 |
1999年 | 22篇 |
1998年 | 91篇 |
1997年 | 73篇 |
1996年 | 59篇 |
1995年 | 34篇 |
1994年 | 46篇 |
1993年 | 34篇 |
1992年 | 13篇 |
1991年 | 19篇 |
1990年 | 13篇 |
1989年 | 19篇 |
1988年 | 19篇 |
1987年 | 10篇 |
1986年 | 13篇 |
1985年 | 13篇 |
1984年 | 8篇 |
1983年 | 13篇 |
1982年 | 10篇 |
1981年 | 10篇 |
1980年 | 9篇 |
1979年 | 16篇 |
1978年 | 15篇 |
1977年 | 18篇 |
1976年 | 30篇 |
1975年 | 18篇 |
1974年 | 8篇 |
排序方式: 共有1574条查询结果,搜索用时 15 毫秒
1.
El-Denglawey A. Issa Shams A. M. Saddeek Yasser B. Tekin H. O. Zakaly Hesham M. H. 《Journal of Inorganic and Organometallic Polymers and Materials》2021,31(10):3934-3942
Journal of Inorganic and Organometallic Polymers and Materials - This work aimed to investigate the impact of Lead-fluoride based glasses via theoretical and simulation techniques on mechanical and... 相似文献
2.
3.
Mohsen A. Issa Mahmoud A. Issa H. Abdalla Md. S. Islam A. Chudnovsky 《Probabilistic Engineering Mechanics》2002,17(2)
In the present work, the distribution of the random toughness characteristics (i.e. critical energy release rate, G1c) has been evaluated on the basis of experimental observations. Fracture test results from three groups of geometrically similar concrete specimens of size (width×total depth×thickness), 420×420×50–1680×1680×200 mm3, made with different maximum aggregate size of 9.5, 19, 38, and 76 mm were analyzed using a recently proposed distribution of extremes. In applications of probability, it is important to use an appropriate distribution type and adequate techniques for estimating the parameters of distribution. In this study, a new type distribution of minima is employed for probability computations. It was noticed that the entropy of distribution increases with the crack length, i.e. the uncertainty of toughness, G1c, value increases with crack length. A non-linear reduction of the maximum allowable splitting force with the defect size, a, was noticed. For large specimens, the maximum allowable splitting load is more sensitive to the required reliability level than that for small specimens. Reliability increases with aggregate size when all other conditions were constant. 相似文献
4.
Summary Both preferential adsorption coefficient λ and intrinsic viscosity [η] for poly (di-o-alkylphenyl methacrylates) /Tetrahydrofuran
(THF)/water have been determined. The results are discussed in relation to the steric effect of the ortho-substituent groups
on the aromatic ring. 相似文献
5.
Three interesterified vegetable oils (IVOs) prepared from palm, cottonseed, and olive oil, respectively, have been studied for application to Frankfurters. Beef fat (10%) was replaced by one of the IVOs at 20, 60 or 100%. Fatty acid composition of the lipid fraction in the Frankfurters and saturated/unsaturated ratios were established for all batches. We found that total or partial replacement of beef fat by IVOs did not lead to significant changes in appearance, colour, texture, flavour or sensory score. We conclude that IVOs may be successfully applied as beef fat substitutes in Frankfurters. 相似文献
6.
7.
8.
9.
10.
Two experiments explore whether synchrony between peak circadian arousal periods and time of testing influences inhibitory efficiency for younger and older adults. Experiment 1 assesses inhibitory control over no-longer-relevant thoughts, and Experiment 2 assesses control over unwanted but strong responses, as well as performance on neuropsychological tasks that index frontal function. Inhibitory control is greatest at optimal times for both age groups and is generally greater for younger than for older adults. Performance on 2 neuropsychological measures (Stroop and Trails) also changes over the day, at least for older adults, and is correlated with inhibitory indexes, suggesting that for older adults changes in inhibition may be mediated by circadian variations in frontal functioning. By contrast, access to well-learned responses is not vulnerable to synchrony or age effects. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献