全文获取类型
收费全文 | 4030篇 |
免费 | 213篇 |
国内免费 | 12篇 |
专业分类
电工技术 | 43篇 |
综合类 | 10篇 |
化学工业 | 1117篇 |
金属工艺 | 80篇 |
机械仪表 | 69篇 |
建筑科学 | 84篇 |
矿业工程 | 13篇 |
能源动力 | 154篇 |
轻工业 | 209篇 |
水利工程 | 28篇 |
石油天然气 | 15篇 |
武器工业 | 2篇 |
无线电 | 354篇 |
一般工业技术 | 909篇 |
冶金工业 | 561篇 |
原子能技术 | 66篇 |
自动化技术 | 541篇 |
出版年
2023年 | 35篇 |
2022年 | 115篇 |
2021年 | 176篇 |
2020年 | 72篇 |
2019年 | 84篇 |
2018年 | 108篇 |
2017年 | 106篇 |
2016年 | 125篇 |
2015年 | 103篇 |
2014年 | 175篇 |
2013年 | 278篇 |
2012年 | 206篇 |
2011年 | 248篇 |
2010年 | 180篇 |
2009年 | 187篇 |
2008年 | 193篇 |
2007年 | 161篇 |
2006年 | 122篇 |
2005年 | 119篇 |
2004年 | 114篇 |
2003年 | 113篇 |
2002年 | 112篇 |
2001年 | 73篇 |
2000年 | 58篇 |
1999年 | 59篇 |
1998年 | 105篇 |
1997年 | 85篇 |
1996年 | 74篇 |
1995年 | 50篇 |
1994年 | 46篇 |
1993年 | 41篇 |
1992年 | 33篇 |
1991年 | 22篇 |
1990年 | 37篇 |
1989年 | 22篇 |
1988年 | 15篇 |
1987年 | 19篇 |
1986年 | 22篇 |
1985年 | 19篇 |
1984年 | 26篇 |
1983年 | 24篇 |
1982年 | 22篇 |
1981年 | 20篇 |
1980年 | 19篇 |
1979年 | 18篇 |
1977年 | 14篇 |
1976年 | 26篇 |
1975年 | 18篇 |
1965年 | 12篇 |
1964年 | 12篇 |
排序方式: 共有4255条查询结果,搜索用时 31 毫秒
1.
Olga Yu Kurapova Sergey M. Shugurov Evgenia A. Vasil'eva Daniil A. Savelev Vladimir G. Konakov Sergey I. Lopatin 《Ceramics International》2021,47(8):11072-11079
Ceria-based solid solutions are important materials for high- and medium-temperature electrochemical applications. However, the stabilities of both binary and ternary ceria-based solid solutions are insufficient at elevated temperatures, which limits their application as solid electrolytes or SOFC cathodes. Data on the high-temperature stability of ceria-based ceramics are unavailable in the literature. In the present study, we report a thermodynamic stability investigation of Y2O3-CeO2 and Y2O3-ZrO2-CeO2 solid solutions. The thermal prehistories of binary and ternary systems were investigated using STA, XRD, and ESCA techniques. The vaporization processes were investigated in the temperature range of 1577–2227°С via the Knudsen effusion mass spectrometry technique. Using data on the component activity in solid-phase thermodynamic properties of Y2O3-CeO2 solid solutions, which is represented as the Gibbs energy, the excess Gibbs energy was calculated as a function of the ceria mol. %. It was shown that the reduction of Ce4+ to Ce3+ in Y2O3-CeO2 and Y2O3-ZrO2-CeO2 solid solutions corresponds to less-negative Gibbs energy compared to ZrO2-CeO2 solid solutions. 相似文献
2.
An effective practical approach that allows not only a significant reduction in the scope of practical experiments in the course of studying suspension separation processes in hydrocyclones, but also makes it possible to assess the intensity of random components of the processes and define the interrelation between such components and hydrodynamics of flows in a hydrocyclone is presented. Within the frames of the developed probabilistic‐statistical model of suspension separation in hydrocyclones on the basis of statistical self‐similarity properties, a relationship was found between determined and random components of the processes. This allowed transitioning from three‐parameter probability density functions for suspension particles in hydrocyclones to two‐parameter functions; thus significantly improving the efficiency of practical application of the developed model. 相似文献
3.
4.
Reports an error in "Tradeoffs and Theory: The Double-Mediation Model" by Marc Scholten and Steven J. Sherman (Journal of Experimental Psychology: General, 2006 May, Vol 135[2], 237-261). This article was inadvertently printed with the incorrect title. The original title was "Tradeoffs and Conflict: The Double-Mediation Model." This title highlights the relation between tradeoffs and conflict as investigated by the authors and accounted for by their model. However, readers are asked to refer to the article by the title with which it was printed to facilitate its retrieval.. (The following abstract of the original article appeared in record 2006-06642-006.) Most theories of decision making suggest that, when options imply tradeoffs between their attributes, conflict increases as tradeoff size increases, because greater sacrifices are to be incurred in choosing one option instead of another. An alternative view is that conflict decreases as tradeoff size increases, because stronger arguments can be made for any decision. The authors propose a unified model, the double-mediation model, which combines the mediating effects of sacrifice and argumentation. Our model generally predicts an inverse U-shaped relation between tradeoff size and conflict. Results support this prediction. Also, when the decision situation increases the mediating effect of sacrifice relative to that of argumentation, the relation between tradeoff size and conflict changes in an upward direction; conversely, when the decision situation increases the mediating effect of argumentation relative to that of sacrifice, the relation changes in a downward direction. Results support these predictions as well. Commonalities and differences between our model and other formulations are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
5.
Vladimir Rozenshtein Alexander Berg Haim Levanon Uwe Krueger Dietmar Stehlik Yuri Kandrashkin Art Van Der Est 《Israel journal of chemistry》2003,43(3-4):373-381
Light-induced spin-polarized transient EPR spectra are reported for several water-soluble copper porphyrins. The spectra are assigned to the doublet ground state, with emissive spin polarization resulting from photoexcitation and subsequent electronic relaxation. In contrast to other systems for which polarization of a doublet ground state has been observed, the exchange interactions in the copper porphyrins are strong and the geometry is fixed. It is proposed that intersystem crossing from the photoexcited trip-doublet to the trip-quartet state can lead to net polarization of the spin system and that this polarization is maintained during electronic decay, possibly via charge-transfer and exciplex states. The intensity of the observed spin polarization is essentially independent of the molecular orientation in the external field, but is strongly dependent on the nature of the charged peripheral groups. Possible reasons for this behavior are discussed. 相似文献
6.
7.
8.
Brezina V 《Neurocomputing》2007,70(10-12):1863-1869
Variability of the neuronal spike pattern is usually thought of in terms of the information that the different interspike intervals might be encoding. However, the very presence of the variability can have other kinds of functional significance. Here we consider the example of the B15/B16-ARC neuromuscular system of Aplysia, a model system for the study of neuromuscular modulation and control. We show that variability of motor neuron spike timing at the input to the system penetrates throughout the system, affecting all downstream variables including modulator release, modulator concentrations, modulatory actions, and the contraction of the muscle. Furthermore, not only does the variability penetrate through the system, but it is actually instrumental in maintaining its modulation and contractions at a robust, physiological level. 相似文献
9.
Mark Sherman Jonathan Rosenberg Ann Marks Jaap Akkerhuis 《Computer Standards & Interfaces》1991,11(3):177-182
Many advanced document systems provide a formatting mechanism called ‘style sheets’ Style sheets provide a great deal of flexibility in describing a document's format, and allow easy maintenance of different house styles for a collection of documents. In this paper, we describe the basics of general style sheet systems, argue that successful document interchange must include the exchange of style sheet information, and evaluate ODA's style mechanism against this requirement. 相似文献
10.