全文获取类型
收费全文 | 5846篇 |
免费 | 121篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 73篇 |
综合类 | 3篇 |
化学工业 | 1013篇 |
金属工艺 | 128篇 |
机械仪表 | 100篇 |
建筑科学 | 273篇 |
矿业工程 | 26篇 |
能源动力 | 111篇 |
轻工业 | 384篇 |
水利工程 | 50篇 |
石油天然气 | 55篇 |
无线电 | 564篇 |
一般工业技术 | 708篇 |
冶金工业 | 1767篇 |
原子能技术 | 43篇 |
自动化技术 | 673篇 |
出版年
2022年 | 42篇 |
2021年 | 58篇 |
2019年 | 54篇 |
2018年 | 57篇 |
2017年 | 87篇 |
2016年 | 79篇 |
2015年 | 67篇 |
2014年 | 83篇 |
2013年 | 294篇 |
2012年 | 131篇 |
2011年 | 185篇 |
2010年 | 156篇 |
2009年 | 175篇 |
2008年 | 189篇 |
2007年 | 193篇 |
2006年 | 181篇 |
2005年 | 189篇 |
2004年 | 130篇 |
2003年 | 166篇 |
2002年 | 122篇 |
2001年 | 138篇 |
2000年 | 94篇 |
1999年 | 133篇 |
1998年 | 333篇 |
1997年 | 228篇 |
1996年 | 183篇 |
1995年 | 123篇 |
1994年 | 122篇 |
1993年 | 109篇 |
1992年 | 93篇 |
1991年 | 83篇 |
1990年 | 97篇 |
1989年 | 90篇 |
1988年 | 89篇 |
1987年 | 87篇 |
1986年 | 75篇 |
1985年 | 90篇 |
1984年 | 72篇 |
1983年 | 75篇 |
1982年 | 72篇 |
1981年 | 58篇 |
1980年 | 57篇 |
1979年 | 59篇 |
1978年 | 53篇 |
1977年 | 76篇 |
1976年 | 102篇 |
1975年 | 42篇 |
1974年 | 47篇 |
1973年 | 54篇 |
1972年 | 44篇 |
排序方式: 共有5971条查询结果,搜索用时 15 毫秒
1.
Felipe A. Perdomo Siti H. Khalit Claire S. Adjiman Amparo Galindo George Jackson 《American Institute of Chemical Engineers》2021,67(3):e17194
The SAFT-γ Mie group-contribution equation of state is used to represent the fluid-phase behavior of aqueous solutions of a variety of linear, branched, and cyclic amines. New group interactions are developed in order to model the mixtures of interest, including the like and unlike interactions between alkyl primary, secondary, and tertiary amine groups (NH2, NH, N), cyclic secondary and tertiary amine groups (cNH, cN), and cyclic methine-amine groups (cCHNH, cCHN) with water (H2O). The group-interaction parameters are estimated from appropriate experimental thermodynamic data for pure amines and selected mixtures. By taking advantage of the group-contribution nature of the method, one can describe the fluid-phase behavior of mixtures of molecules comprising those groups over broad ranges of temperature, pressure, and composition. A number of aqueous solutions of amines are studied including linear, branched aliphatic, and cyclic amines. Liquid–liquid equilibria (LLE) bounded by lower critical solution temperatures (LCSTs) have been reported experimentally and are reproduced here with the SAFT-γ Mie approach. The main feature of the approach is the ability not only to represent accurately the experimental data employed in the parameter estimation, but also to predict the vapor–liquid, liquid–liquid, and vapor–liquid–liquid equilibria, and LCSTs with the same set of parameters. Pure compound and binary phase diagrams of diverse types of amines and their aqueous solutions are assessed in order to demonstrate the main features of the thermodynamic and fluid-phase behavior. 相似文献
2.
3.
4.
van Dick Rolf; Wagner Ulrich; Pettigrew Thomas F.; Christ Oliver; Wolf Carina; Petzel Thomas; Castro Vanessa Smith; Jackson James S. 《Canadian Metallurgical Quarterly》2004,87(2):211
Furthering G. W. Allport's (1954) contentions for optimal contact, the authors introduce a new construct: the perceived importance of contact. They propose that perceived importance is the best proximal predictor of contact's reduction of prejudice. If individuals have opportunities for contact at work or in the neighborhood, their chances to have intergroup acquaintances and friends increase. Intergroup contact among acquaintances and friends can be perceived as more or less important, which in turn determines intergroup evaluations. A 1st study shows that the new measure of perceived importance is indeed distinct from established quantity and quality indicators. The results are cross-validated in a 2nd study that also sheds light on the meaning of importance. In 3rd and 4th studies, structural equation analyses and a meta-analysis support the hypotheses. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
5.
Systematic assessment of anger among people with developmental disabilities has been lacking, especially for hospital inpatients. Reliability and validity of anger self-report psychometric scales were investigated with 129 male patients, mostly forensic. Anger prevalence and its relationship to demographic, cognitive, and personality variables and to hospital assaultive behavior were examined. High internal and intermeasure consistency, and some concurrent validity with staff ratings, were found. Retrospective validity regarding physically assaultive behavior in the hospital was obtained. Hierarchical regressions revealed that patient-reported anger was a significant predictor of assaults postadmission, controlling for age, length of stay, IQ, violence offense history, and personality variables. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
6.
7.
8.
Hannes Verlinde Martine De Cock Raymond Boute 《IEEE transactions on systems, man, and cybernetics. Part B, Cybernetics》2006,36(3):679-684
As opposed to quantitative association rule mining, fuzzy association rule mining is said to prevent the overestimation of boundary cases, as can be shown by small examples. Rule mining, however, becomes interesting in large databases, where the problem of boundary cases is less apparent and can be further suppressed by using sensible partitioning methods. A data-driven approach is used to investigate if there is a significant difference between quantitative and fuzzy association rules in large databases. The influence of the choice of a particular triangular norm in this respect is also examined. 相似文献
9.
Values of D0 /δ and Q for grain-boundary diffusion, derived from published studies of normal grain growth in Al2 O3 , BeO, CaO, MgO, SiO2 , and CaSiO3 , are fit by the linear compensation equation log D0 /δ=0.03170Q -7.6792 (r2 =0.9384). Comparison of grain-boundary diffusion coefficients derived from grain growth in oxides with those obtained by direct experimental measurement suggests that the kinetics of normal grain growth are controlled by grain-boundary diffusion of oxygen. 相似文献
10.
We consider the dynamics of a dark soliton in an elongated harmonically trapped Bose-Einstein condensate. A central question
concerns the behavior at finite temperatures, where dissipation arises due to the presence of a thermal cloud. We study this
problem using coupled Gross-Pitaevskii and N-body simulations, which include the mean field coupling between the condensate and thermal cloud. We find that the soliton
decays relatively quickly even at very low temperatures, with the decay rate increasing with rising temperature. 相似文献