全文获取类型
收费全文 | 286285篇 |
免费 | 4160篇 |
国内免费 | 306篇 |
专业分类
电工技术 | 4342篇 |
综合类 | 114篇 |
化学工业 | 48393篇 |
金属工艺 | 15852篇 |
机械仪表 | 10846篇 |
建筑科学 | 5338篇 |
矿业工程 | 3837篇 |
能源动力 | 4758篇 |
轻工业 | 15909篇 |
水利工程 | 4438篇 |
石油天然气 | 13130篇 |
武器工业 | 33篇 |
无线电 | 21710篇 |
一般工业技术 | 68801篇 |
冶金工业 | 39903篇 |
原子能技术 | 11298篇 |
自动化技术 | 22049篇 |
出版年
2021年 | 3799篇 |
2020年 | 2952篇 |
2019年 | 3642篇 |
2018年 | 6914篇 |
2017年 | 7172篇 |
2016年 | 7558篇 |
2015年 | 4188篇 |
2014年 | 6711篇 |
2013年 | 12853篇 |
2012年 | 9530篇 |
2011年 | 11130篇 |
2010年 | 9039篇 |
2009年 | 9701篇 |
2008年 | 9689篇 |
2007年 | 9289篇 |
2006年 | 7363篇 |
2005年 | 6438篇 |
2004年 | 6262篇 |
2003年 | 6000篇 |
2002年 | 5793篇 |
2001年 | 5439篇 |
2000年 | 5406篇 |
1999年 | 4760篇 |
1998年 | 9621篇 |
1997年 | 7445篇 |
1996年 | 5475篇 |
1995年 | 4302篇 |
1994年 | 3934篇 |
1993年 | 4170篇 |
1992年 | 3420篇 |
1991年 | 3581篇 |
1990年 | 3647篇 |
1989年 | 3534篇 |
1988年 | 3438篇 |
1987年 | 3406篇 |
1986年 | 3292篇 |
1985年 | 3466篇 |
1984年 | 3377篇 |
1983年 | 3256篇 |
1982年 | 3133篇 |
1981年 | 3196篇 |
1980年 | 3222篇 |
1979年 | 3325篇 |
1978年 | 3568篇 |
1977年 | 3704篇 |
1976年 | 4447篇 |
1975年 | 3258篇 |
1974年 | 3338篇 |
1973年 | 3411篇 |
1972年 | 3012篇 |
排序方式: 共有10000条查询结果,搜索用时 406 毫秒
81.
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82.
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
83.
Quality enhancement of the abundant under‐valued crustacean,lobster krill (Munida spp.), during its chilled storage
下载免费PDF全文
![点击此处可从《International Journal of Food Science & Technology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
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
84.
Strength of Materials - The statistical analysis performed on the defectiveness of rails in the Kiev subway railway shows that the main cause of the occurrence of most defects is the contact... 相似文献
85.
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
86.
Strength of Materials - Methodical aspects of experimental investigation of brittle materials under local edge loading by scratching the specimen surface with a Rockwell indenter to its edge... 相似文献
87.
Measurement Techniques - A method is proposed for transferring the unit of mean power of laser radiation by means of measuring high-intensity power (kilowatts), with the possibility of constant... 相似文献
88.
In this paper, a new inverse identification method of constitutive parameters is developed from full kinematic and thermal field measurements. It consists in reconstructing the heat source field from two different approaches by using the heat diffusion equation. The first one requires the temperature field measurement and the value of the thermophysical parameters. The second one is based on the kinematic field measurement and the choice of a thermo-hyperelastic model that contains the parameters to be identified. The identification is carried out at the local scale, ie, at any point of the heat source field, without using the boundary conditions. In the present work, the method is applied to the challenging case of hyperelasticity from a heterogeneous test. Due to large deformations undergone by the rubber specimen tested, a motion compensation technique is developed to plot the kinematic and the thermal fields at the same points before reconstructing the heterogeneous heat source field. In the present case, the constitutive parameter of the Neo-Hookean model has been identified, and its distribution has been characterized with respect to the strain state at the surface of a cross-shaped specimen. 相似文献
89.
Semiconductors - On the basis of the Monte Carlo algorithm, a method for calculating the energy spectrum of hot nonequilibrium electrons and holes in the track of a primary recoil atom after being... 相似文献
90.