全文获取类型
收费全文 | 576621篇 |
免费 | 6763篇 |
国内免费 | 2269篇 |
专业分类
电工技术 | 10335篇 |
综合类 | 2962篇 |
化学工业 | 80048篇 |
金属工艺 | 26196篇 |
机械仪表 | 20548篇 |
建筑科学 | 12914篇 |
矿业工程 | 3278篇 |
能源动力 | 12699篇 |
轻工业 | 38981篇 |
水利工程 | 6221篇 |
石油天然气 | 9485篇 |
武器工业 | 48篇 |
无线电 | 69477篇 |
一般工业技术 | 115389篇 |
冶金工业 | 98606篇 |
原子能技术 | 11449篇 |
自动化技术 | 67017篇 |
出版年
2021年 | 3529篇 |
2020年 | 2652篇 |
2019年 | 3389篇 |
2018年 | 23914篇 |
2017年 | 23401篇 |
2016年 | 17709篇 |
2015年 | 4926篇 |
2014年 | 7141篇 |
2013年 | 19540篇 |
2012年 | 15559篇 |
2011年 | 29147篇 |
2010年 | 24691篇 |
2009年 | 23547篇 |
2008年 | 24849篇 |
2007年 | 26990篇 |
2006年 | 12922篇 |
2005年 | 15618篇 |
2004年 | 14095篇 |
2003年 | 13517篇 |
2002年 | 11891篇 |
2001年 | 11516篇 |
2000年 | 10931篇 |
1999年 | 11582篇 |
1998年 | 30455篇 |
1997年 | 20906篇 |
1996年 | 16082篇 |
1995年 | 12002篇 |
1994年 | 10520篇 |
1993年 | 10536篇 |
1992年 | 7337篇 |
1991年 | 7083篇 |
1990年 | 6854篇 |
1989年 | 6680篇 |
1988年 | 6160篇 |
1987年 | 5351篇 |
1986年 | 5393篇 |
1985年 | 6035篇 |
1984年 | 5431篇 |
1983年 | 4970篇 |
1982年 | 4646篇 |
1981年 | 4807篇 |
1980年 | 4589篇 |
1979年 | 4295篇 |
1978年 | 4271篇 |
1977年 | 4911篇 |
1976年 | 6552篇 |
1975年 | 3646篇 |
1974年 | 3526篇 |
1973年 | 3506篇 |
1972年 | 2975篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
41.
Solov’ev V. P. Tsivadze A. Yu. 《Protection of Metals and Physical Chemistry of Surfaces》2015,51(1):1-35
Stability constants and formation enthalpies of supramolecular complexes of crown ethers and their cyclic and acyclic analogues are determined on the basis of experimental data obtained by different physicochemical methods in the terms of a general approach developed and implemented in the ChemEqui software package. The established regularities of variation of stability of complexes are discussed as dependent on the ligand structure, nature of the cation, solvent, and anion. The applicability of the suggested method of determining complexation selectivity is shown for multicomponent equilibria in solutions.
相似文献42.
V. E. Gromov A. M. Glezer K. V. Morozov Yu. F. Ivanov K. V. Volkov 《Russian Metallurgy (Metally)》2015,2015(13):1094-1097
A layer-by-layer analysis of the structures, the phase compositions, and the defect substructures of differentially hardened rails has been carried by optical and transmission electron microscopy. It is found that the material volume of the rail head fillet is cooled faster than the volume located along the central axis. 相似文献
43.
Quality enhancement of the abundant under‐valued crustacean,lobster krill (Munida spp.), during its chilled storage 下载免费PDF全文
Bibiana García‐Soto José M. Miranda Jorge Barros‐Velázquez Santiago P. Aubourg 《International Journal of Food Science & Technology》2015,50(3):708-716
Lobster krill (Munida genus) represents an under‐valued crustacean frequently caught on European fishing banks. In this work, its sensory, microbiological and biochemical qualities were evaluated during chilled storage. Additionally, the effects of a prestorage antimelanosic treatment consisting of soaking in sodium metabisulphite (SMB) solutions at two different concentrations (0.25% and 0.75%) were also studied. SMB prestorage treatment provided lobster specimens that still exhibited acceptable sensory quality after 10 days of storage, while control specimens were unacceptable at that time. SMB treatment also resulted in a significant (P < 0.05) inhibition of microbial growth, mainly of Enterobacteriaceae, psychrotrophes and proteolytic bacteria. Low lipid oxidation levels were observed for all batches; however, a significantly higher (P < 0.05) retention of polyunsaturated fatty acids was found in SMB‐treated lobster, especially in the 0.75% SMB batch. The results presented here open the way to the potential commercialisation of currently under‐utilised lobster krill as a chilled product. 相似文献
44.
45.
Journal of Communications Technology and Electronics - Abstract—The article considers the two-dimensional diffraction problem of a TM-type plane electromagnetic wave on a cylindrical silver... 相似文献
46.
Loboda P. I. Minitsky A. V. Byba Ye. G. Sysoev M. O. Radchuk S. V. 《Powder Metallurgy and Metal Ceramics》2020,58(11-12):651-656
Powder Metallurgy and Metal Ceramics - The infiltration of aluminum melts into porous metal skeletons produced by powder metallurgy methods, including 3D printing, under a pressure gradient was... 相似文献
47.
Wireless Personal Communications - In the fusion experiment, sensitive radio frequency signal diagnostic instruments need to be protected against high power stray radiation coming from the Electron... 相似文献
48.
J. Cochard P. Léonide J. Borgomano Y. Guglielmi G. Massonnat J-P. Rolando L. Marié A. Pasquier 《Journal of Petroleum Geology》2020,43(1):75-94
Upper Barremian – Lower Aptian inner platform “Urgonian” limestones in the Mont de Vaucluse region, SE France, consist of alternating metre-scale microporous and tight intervals. This paper focuses on the influence of structural deformation on the reservoir properties of the Urgonian limestone succession in a study area near the town of Rustrel. Petrographic, petrophysical and structural data were recovered from five fully-cored boreholes, from the walls of a 100 m long underground tunnel, and from a 50 m long transect at a nearby outcrop. The data allowed reservoir property variations in the Urgonian limestones to be studied from core to reservoir scale. Eleven Reservoir Rock Types (RRTs) were identified based on petrographic features (texture, grain size), reservoir properties (porosity, permeability), and the frequency of structural discontinuities such as fractures, faults and stylolites. Tight and microporous reservoir rock types were distinguished. Tight reservoir rock types were characterised by early cementation of intergranular pore spaces and by the presence of frequent structural discontinuities. By contrast microporous reservoir rock types contained preserved intragranular microporosity and matrix permeability, but had very few structural discontinuities. Observed vertical alternations of microporous and tight rock types are interpreted to have been controlled by the early diagenesis of the Urgonian carbonates. Deformation associated with regional-scale tectonic phases, including Albian – Cenomanian “Durancian” uplift (∼105 to 96 Ma) and Pyrenean compression (∼55 to 25 Ma), resulted in the modification of the initial petrophysical properties of the Urgonian limestones. An early diagenetic imprint conditioned both the intensity of structural deformations and the associated circulations of diagenetic and meteoric fluids. Evolution of the Reservoir Rock Types is therefore linked both to the depositional conditions and to subsequent phases of structural deformation. 相似文献
49.
50.