全文获取类型
收费全文 | 852篇 |
免费 | 28篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 7篇 |
综合类 | 1篇 |
化学工业 | 232篇 |
金属工艺 | 19篇 |
机械仪表 | 19篇 |
建筑科学 | 18篇 |
矿业工程 | 2篇 |
能源动力 | 31篇 |
轻工业 | 37篇 |
水利工程 | 1篇 |
石油天然气 | 7篇 |
无线电 | 82篇 |
一般工业技术 | 226篇 |
冶金工业 | 52篇 |
原子能技术 | 13篇 |
自动化技术 | 135篇 |
出版年
2024年 | 5篇 |
2022年 | 18篇 |
2021年 | 26篇 |
2020年 | 18篇 |
2019年 | 30篇 |
2018年 | 30篇 |
2017年 | 28篇 |
2016年 | 30篇 |
2015年 | 13篇 |
2014年 | 24篇 |
2013年 | 63篇 |
2012年 | 32篇 |
2011年 | 56篇 |
2010年 | 37篇 |
2009年 | 29篇 |
2008年 | 28篇 |
2007年 | 24篇 |
2006年 | 21篇 |
2005年 | 19篇 |
2004年 | 20篇 |
2003年 | 18篇 |
2002年 | 7篇 |
2001年 | 11篇 |
2000年 | 11篇 |
1999年 | 15篇 |
1998年 | 15篇 |
1997年 | 15篇 |
1996年 | 13篇 |
1995年 | 19篇 |
1994年 | 17篇 |
1993年 | 16篇 |
1992年 | 24篇 |
1991年 | 11篇 |
1990年 | 4篇 |
1989年 | 10篇 |
1988年 | 8篇 |
1987年 | 8篇 |
1986年 | 5篇 |
1985年 | 11篇 |
1984年 | 13篇 |
1983年 | 6篇 |
1982年 | 5篇 |
1981年 | 5篇 |
1980年 | 9篇 |
1979年 | 13篇 |
1978年 | 6篇 |
1976年 | 4篇 |
1974年 | 5篇 |
1973年 | 7篇 |
1971年 | 3篇 |
排序方式: 共有882条查询结果,搜索用时 15 毫秒
61.
Low-stress creep behaviour of a two-phase Zr–2.5%Nb alloy, differently heat treated, has been investigated using helical test
specimens. The phase diagram of the α (hcp) + β (bcc) alloy is characterized by the monotectoid reaction at 893 ± 10 K: β
1 → (α + β
2) where β
1 (Zr–20Nb) and β
2 (Zr–80Nb) have widely differing compositions. At the creep testing temperature, 818 K, which is close to but below the monotectoid
temperature, the creep rate for samples with the equilibrium α + β
2 structure has been found to be considerably higher, over an order of magnitude, than that in samples with the metastable
α + β
1 structure. Microstructural changes accompanying the markedly enhanced creep rate for the α + β
2 structure at stresses as low as 1–4 MPa have been explained in terms of the relative stability of the β
1 and the β
2 phases during the creep process. An attempt has been made to elicit the likely mechanism underlying the observed enhancement
of creep rate and the changes in morphology, composition and volume fraction of the β phase. 相似文献
62.
The effect of alkali and alkaline earth oxides on the crystallization of lithia-alumina-silica glasses has been studied. Crystallization
behaviour of glasses has been investigated using DTA and XRD techniques. The principal crystallization phases are identified
asβ-spodumene solid solution and lithium metasilicate. The crystallization temperature of glasses decreases with increase in
the values of the ionic field strength of the alkali and alkaline earth cations. Addition of these oxides at lower concentrations
has no significant effect on the crystalline phases. 相似文献
63.
64.
65.
66.
This short note reports the results concerning electron paramagnetic resonance (EPR) and optical absorption spectra of Cu2+ ions doped in sodium potassium sulphate both at 300K and 77K. 相似文献
67.
Reproducible, nondestructive methods of prooftesting continuous, multikllometer lengths of high-strength (>1.4 GPa) optical fiber are important in high-performance applications of lightguide technology. An alternative prooftester based on the concept of continuously imparting a constant strain rather than a constant weight to the optical fiber has been built and tested. The constant-strain design is somewhat simpler and has certain advantages over a widely used prooftester. The constant-strain method is explained, and prooftest data that substantiate the advantages of the design are presented. 相似文献
68.
Using the basic equations of heat conducting micropolar fluid, heat transfer through a channel of porous walls has been studied. The temperature distribution is obtained for different values of suction parameter , convective parameter and micropolar parameter . 相似文献
69.
Michael Netzel Gabriele Netzel Dimitrios Zabaras Leif Lundin Li Day Rama Addepalli Simone A. Osborne Robert Seymour 《Food research international (Ottawa, Ont.)》2011,44(4):868-874
The release and absorption (bioavailability) of carotenoids is a prerequisite for their nutritional impact. This can be strongly affected by the processing conditions used to prepare the food matrix that contains them. To determine the effect of processing on carotenoid bioavailability, homogenized, raw, blanched and cooked carrots were exposed to an in vitro gastric and intestinal digestion model. Final digest samples were placed onto a Caco-2 cell trans-well monolayer culture to mimic intestinal absorption. The results show that the cooked carrot puree consisting of primarily single plant cell particles had the highest release of carotenes, followed by blanched consisting primarily of plant cell clusters and raw carrot puree consisting of larger plant cell clusters. Absorption through the Caco-2 cell layer was the highest from the digesta of cooked carrot puree followed by the digesta of blanched carrot puree. This study demonstrates that thermal processing and/or mechanical homogenization to disrupt plant cell wall matrix enhances the in vitro bioavailability of carotenes from carrots. 相似文献
70.
L. Rama Krishna G. Sundararajan 《JOM Journal of the Minerals, Metals and Materials Society》2014,66(6):1045-1060
Magnesium (Mg) and its alloys, in the current era of persistently growing engineering demands, have become the most promising materials finding widespread industrial applications. Numerous processes are available for surface protection of Mg and its alloys to potentially minimize corrosion damage. The micro arc oxidation (MAO), a fairly recent and eco-friendly coating process, emerged as a novel means to provide an adherent, hard, scratch-resistant, wear-resistant, and corrosion-resistant coatings on Mg alloys. However, the successful utilization of such coatings demands a thorough understanding of the influence of a relatively large number of process parameters such as electrolytic composition, presence of insoluble additives in the electrolyte, electrical parameters employed, and the composition of the Mg alloy substrate on the corrosion resistance. The detailed influence of all the above parameters on the corrosion behavior of Mg alloys is critically reviewed and presented in this article. In addition, this article also reviews the recent trends in terms of duplexing the MAO process using different techniques/processes such that the composite coatings are produced with enhanced corrosion resistance. 相似文献