全文获取类型
收费全文 | 18242篇 |
免费 | 1487篇 |
国内免费 | 1254篇 |
专业分类
电工技术 | 1047篇 |
综合类 | 1613篇 |
化学工业 | 588篇 |
金属工艺 | 705篇 |
机械仪表 | 1679篇 |
建筑科学 | 501篇 |
矿业工程 | 463篇 |
能源动力 | 419篇 |
轻工业 | 692篇 |
水利工程 | 179篇 |
石油天然气 | 419篇 |
武器工业 | 250篇 |
无线电 | 1257篇 |
一般工业技术 | 861篇 |
冶金工业 | 1149篇 |
原子能技术 | 132篇 |
自动化技术 | 9029篇 |
出版年
2024年 | 41篇 |
2023年 | 116篇 |
2022年 | 302篇 |
2021年 | 373篇 |
2020年 | 408篇 |
2019年 | 395篇 |
2018年 | 325篇 |
2017年 | 433篇 |
2016年 | 544篇 |
2015年 | 652篇 |
2014年 | 970篇 |
2013年 | 944篇 |
2012年 | 1093篇 |
2011年 | 1300篇 |
2010年 | 1073篇 |
2009年 | 1206篇 |
2008年 | 1295篇 |
2007年 | 1443篇 |
2006年 | 1345篇 |
2005年 | 1170篇 |
2004年 | 969篇 |
2003年 | 891篇 |
2002年 | 679篇 |
2001年 | 564篇 |
2000年 | 411篇 |
1999年 | 399篇 |
1998年 | 328篇 |
1997年 | 264篇 |
1996年 | 224篇 |
1995年 | 164篇 |
1994年 | 132篇 |
1993年 | 85篇 |
1992年 | 62篇 |
1991年 | 50篇 |
1990年 | 44篇 |
1989年 | 45篇 |
1988年 | 31篇 |
1987年 | 22篇 |
1986年 | 13篇 |
1985年 | 16篇 |
1984年 | 12篇 |
1966年 | 9篇 |
1965年 | 9篇 |
1964年 | 10篇 |
1963年 | 8篇 |
1962年 | 8篇 |
1960年 | 13篇 |
1959年 | 12篇 |
1957年 | 9篇 |
1955年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
92.
Miller Mark W.; Greif Jennifer L.; Smith Alethea A. 《Canadian Metallurgical Quarterly》2003,15(2):205
This study used the Multidimensional Personality Questionnaire (MPQ; A. Tellegen, in press) to identify personality-based subtypes of posttraumatic response. Cluster analyses of MPQs completed by combat veterans revealed subgroups that differed on measures relating to the externalization versus internalization of distress. The MPQ profile of the externalizing cluster was defined by low Constraint and Harmavoidance coupled with high Alienation and Aggression. Individuals in this cluster also had histories of delinquency and high rates of substance-related disorder. In comparison, the MPQ profile of the internalizing cluster was characterized by lower Positive Emotionality, Alienation, and Aggression and higher Constraint, and individuals in this cluster showed high rates of depressive disorder. These findings suggest that dispositions toward externalizing versus internalizing psychopathology may account for heterogeneity in the expression of posttraumatic responses, including patterns of comorbidity. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
93.
This article reviews the theory of successful intelligence and attempts to construct-validate the theory of successful intelligence. It describes 4 distinct converging operations that have been used in these attempts. Two sets involve internal validation of the structure of the theory and 2 sets external validation of the theory with outside criteria. The internal validation operations involve information-processing (componential) analyses and both exploratory and confirmatory factor analyses. The external validation operations involve correlational analysis and analyses of instructional interventions based on the theory. The results are generally supportive of the theory and suggest that conventional conceptions of intelligence may be too narrow. The theory is of use in consulting because it broadens the scope of skills one looks for in seeking "intelligent" people for hiring, retention, and promotion and in assessing a person's ability to do his or her current job. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
94.
In this study, crisp and fuzzy multiple-goal optimization approaches are respectively introduced to design an optimal biocompatible solvent to a two-stage extractive fermentation with cell recycling for ethanol production. When designing a biocompatible solvent for the extractive fermentation process, many issues, such as extractive efficiency, conversion, amount of solvent utilized and so on, have to be considered. An interactive multiple-goal design procedure is introduced to determine a trade-off result in order to satisfy such contradicted goals. Both approaches could be iterated to solve the interactive multiple-goal design problem in order to yield a trade-off result. However, the crisp optimization design is a tedious task that requires the designer to provide various pairs of the upper bounds for the design problem to obtain the corresponding solution. The fuzzy optimization approach is able to be trade-off several goals simultaneously and to yield the overall satisfactory grade for the product/process design problem. 相似文献
95.
LonWorks总线在锅炉模糊控制系统中的应用 总被引:1,自引:1,他引:0
采用LonWorks总线技术可以提高锅炉控制系统燃烧效率及可靠性、保证环保要求、降低成本、优化网络的热量分配。尤其多台锅炉通过LON总线联网运行能够合理分配负荷,从而达到提高工作效率的目的。 相似文献
96.
U. Bodenhofer 《Soft Computing - A Fusion of Foundations, Methodologies and Applications》2003,7(4):220-227
This paper is devoted to a general concept of openness and closedness with respect to arbitrary fuzzy relations – along with
appropriate opening and closure operators. It is shown that the proposed framework unifies existing concepts, in particular,
the one for fuzzy preorderings as well as the triangular norm-based approach to fuzzy mathematical morphology.
The author acknowledges support of the K
plus Competence Center Program which is funded by the Austrian Government, the Province of Upper Austria, and the Chamber of Commerce
of Upper Austria. 相似文献
97.
Blanchard Kimberly A.; Morgenstern Jon; Morgan Thomas J.; Lobouvie Erich W.; Bux Donald A. 《Canadian Metallurgical Quarterly》2003,17(4):328
Negative consequences are an important component of the substance use change process, yet no standardized measure exists to assess consequences of use. This study evaluated the psychometric properties of the Inventory of Drug Use Consequences, a self-report measure assessing drinking and drug use consequences. Participants (N=252) were assessed at entry into outpatient substance abuse treatment. Items loaded strongly on 1 factor, and internal consistency of the total scale was high. Fifteen items with the highest correlations with the total scale were chosen to represent the construct. The shortened measure exhibited good internal consistency, convergent and discriminant validity, and detected change over time and may be the measure of substance use consequences that is lacking in the field. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
98.
The aluminium species in different tea infusions were investigated, by determining their stability constants and concentration. This was done for some particular samples using a simple experimental method based on the sorption of aluminium on the strongly sorbing resin Chelex 100, by a batch procedure. From the thermodynamic information obtained it is possible to calculate the concentration of the different species, and in particular that of the free metal ion, which is very important for evaluating the adsorption of aluminium on biological membranes. It was found that aluminium in the tea infusions here considered is present at high total concentration, approximately 0.1 mM, but mainly linked to strong complexes, for instance with side reaction coefficient higher than 10(5.11) at pH 3.95 in one case (tea 1). This could be the reason for the low toxicity of aluminium in tea. These strong complexes were not dissociated even in the presence of Chelex 100. In this case only a limiting value of the reaction coefficient could be evaluated. The presence of the very strong complexes was found in all the tea sample here considered. In two of the considered samples (one black and one green tea) a part of Al(III) was linked to less strong complexes, for example with a reaction coefficient 10(4.14) (tea 2, pH 4.20). The presence in the considered tea infusions of other substances able to complex aluminium was also detected, by the well known ligand titration procedure, at concentration ranging from 0.65 to 3.37 mM in three tea infusions, and at somewhat higher concentration in the case of the ready drink, which was also considered for comparison. 相似文献
99.
Racial and ethnic identity (REI) measures are in danger of becoming conceptually meaningless because of evaluators' insistence that they conform to measurement models intended to assess unidimensional constructs, rather than the multidimensional constructs necessary to capture the complexity of internalized racial or cultural socialization. Some aspects of the intersection of REI theoretical constructs with research design and psychometric practices are discussed, and recommendations for more informed use of each are provided. A table that summarizes some psychometric techniques for analyzing multidimensional measures is provided. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
100.
D.E. Kvasov D. Menniti A. Pinnarelli Y.D. Sergeyev N. Sorrentino 《Electric Power Systems Research》2008
In this paper, the problem of global tuning of fuzzy power-system stabilizers (FPSSs) present in a multi-machine power system in order to damp the power system oscillations is considered. In particular, it is formulated as a problem of global minimization of a multiextremal black-box function over a multidimensional hyperinterval. A global optimization technique, recently proposed, is used for solving the stated problem: the search hyperinterval is partitioned into smaller hyperintervals and the objective function is evaluated only at two vertices corresponding to the main diagonal of the generated hyperintervals, thus avoiding unnecessary ponderous simulations. Then, the performances of this technique are numerically compared with ones of a genetic algorithm (GA). 相似文献