全文获取类型
收费全文 | 38435篇 |
免费 | 4494篇 |
国内免费 | 3182篇 |
专业分类
电工技术 | 2774篇 |
技术理论 | 12篇 |
综合类 | 5356篇 |
化学工业 | 1470篇 |
金属工艺 | 705篇 |
机械仪表 | 1886篇 |
建筑科学 | 9571篇 |
矿业工程 | 748篇 |
能源动力 | 632篇 |
轻工业 | 1291篇 |
水利工程 | 732篇 |
石油天然气 | 1824篇 |
武器工业 | 348篇 |
无线电 | 4382篇 |
一般工业技术 | 2552篇 |
冶金工业 | 631篇 |
原子能技术 | 317篇 |
自动化技术 | 10880篇 |
出版年
2024年 | 175篇 |
2023年 | 479篇 |
2022年 | 910篇 |
2021年 | 976篇 |
2020年 | 1084篇 |
2019年 | 906篇 |
2018年 | 916篇 |
2017年 | 1122篇 |
2016年 | 1299篇 |
2015年 | 1499篇 |
2014年 | 2515篇 |
2013年 | 2211篇 |
2012年 | 2816篇 |
2011年 | 3158篇 |
2010年 | 2670篇 |
2009年 | 2685篇 |
2008年 | 2733篇 |
2007年 | 3063篇 |
2006年 | 2679篇 |
2005年 | 2138篇 |
2004年 | 1786篇 |
2003年 | 1440篇 |
2002年 | 1178篇 |
2001年 | 966篇 |
2000年 | 847篇 |
1999年 | 708篇 |
1998年 | 541篇 |
1997年 | 397篇 |
1996年 | 367篇 |
1995年 | 352篇 |
1994年 | 312篇 |
1993年 | 217篇 |
1992年 | 204篇 |
1991年 | 118篇 |
1990年 | 103篇 |
1989年 | 105篇 |
1988年 | 69篇 |
1987年 | 46篇 |
1986年 | 39篇 |
1985年 | 46篇 |
1984年 | 34篇 |
1983年 | 27篇 |
1982年 | 29篇 |
1981年 | 26篇 |
1980年 | 19篇 |
1979年 | 18篇 |
1978年 | 13篇 |
1977年 | 16篇 |
1975年 | 7篇 |
1959年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
131.
T. Bag 《Information Sciences》2006,176(19):2910-2931
In this paper, definitions of strongly fuzzy convergent sequence, l-fuzzy weakly convergent sequence and l-fuzzy weakly compact set are given in a fuzzy normed linear space. The concepts of fuzzy normal structure, fuzzy non-expansive mapping, uniformly convex fuzzy normed linear space are introduced and fixed point theorems for fuzzy non-expansive mappings are proved. 相似文献
132.
A two‐phase flow CFD model using the volume of fluid (VOF) method is presented for predicting the hydrodynamics of falling film flow on inclined plates, corresponding to the surface texture of structured packing. Using the proposed CFD model the influence of the solid surface microstructure, liquid properties and gas flow rate on the flow behavior was investigated. From the simulated results it was shown that under the condition of no gas flow the liquid flow patterns are dependent on the microstructure of the plates, and proper microstructuring of the solid surface will improve the formation of a continuous liquid film. It was also found that liquid properties, especially surface tension, play an important role in determining the thin‐film pattern. However, there are very different liquid film patterns under the action of gas flow. Thinner liquid films break easily, but thicker liquid films can remain continuous even at higher gas flow rates, which demonstrates that all factors affecting the liquid film thickness will affect the liquid film patterns under conditions of counter‐current two‐phase flow. 相似文献
133.
Bullwhip reduction for ARMA demand: The proportional order-up-to policy versus the full-state-feedback policy 总被引:1,自引:0,他引:1
Gerard Gaalman Author Vitae 《Automatica》2006,42(8):1283-1290
A ‘proportional’ order-up-to policy reacting to ARMA demand is analyzed using stochastic optimal control theory. This policy is compared with a full-state-feedback order-up-to policy. Necessary conditions for an optimum of a weighted sum of the inventory and the ordering variances for both policies are formulated. Based on this a relatively simple expression for the ‘full-state’ policy is derived. The comparison between the two policies demonstrates that the ‘intuitively’ designed proportional policy does not fulfill the objective of controlling both the inventory and ordering variance for all parameter values of the demand model as well as the full-state-feedback policy. The full-state-feedback policy outperforms the proportional policy in several aspects. 相似文献
134.
Failure analysis of hollow glasses The failure analysis is very important to clarify damages of hollow glasses. Damages of glass bottle through over pressure are very often linked with damages to persons. This is the reason why the causal research is from particular importance. Different surface characteristics of glass fragments as well as the fracture pattern give hints to the direction of the crack, the stress just before breakage and the reason of stress. A reconstruction of the bottle is a further helpful instrument for cause studies. The difference of the various characteristics of the surface will be explained. Further on there will be discussed different reasons and mechanism of fracture. 相似文献
135.
G. N. Lilis A. Halder S. Telukunta S. Servetto 《International journal for numerical methods in engineering》2007,71(3):277-312
Many problems in geophysics, acoustics, elasticity theory, cancer treatment, food process control and electrodynamics involve study of wave field synthesis (WFS) in some form or another. In the present work, modelling of wave propagation phenomena is studied as a static problem, using finite element method and treating time as an additional spatial dimension. In particular, WFS problems are analysed using discrete methods. It is shown that a fully finite element-based scheme is very natural and effective method for the solution of such problems. Distributed WFS in the context of two-dimensional problems is outlined and incorporation of any geometric or material non-linearities is shown to be straightforward. This has significant implications for problems in geophysics or biological media, where material inhomogeneities are quite prevalent. Numerical results are presented for several problems referring to media with material inhomogeneities and predefined absorption profiles. The method can be extended to three-dimensional problems involving anisotropic media properties in a relatively straightforward manner. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
136.
Generalized null space uncorrelated Fisher discriminant analysis for linear dimensionality reduction
We propose a generalized null space uncorrelated Fisher discriminant analysis (GNUFDA) technique integrating the uncorrelated discriminant analysis and weighted pairwise Fisher criterion. The GNUFDA can effectively deal with the small sample-size problem and perform satisfactorily when the dimensionality of the null space decreases with increase in the number of training samples per class and/or classes, C. The proposed GNUFDA can extract at most C-1 optimal uncorrelated discriminative vectors without being influenced by the null-space dimensionality. 相似文献
137.
138.
化学模式识别法在钢铁工业中的若干应用 总被引:1,自引:0,他引:1
本文涉及一种崭新的非函数数据处理法及其在工业诊断和优化中的应用。并对其进行要因分析和优化决策的原理作了介绍。结合钢铁工业生产中的实例进行了分析。还探讨了该方法在钢铁工业中应用的意义。 相似文献
139.
Gerardo Gabriel Acosta Miguel Angel Mayosky José Maria Catalfo 《Applied Intelligence》1994,4(1):53-66
This article proposes a scheme for the on-line adjustment of three mode controller settings based on experimental measurements of closed-loop performance. It uses a recently developed heuristic tuning procedure to identify estimated process parameters. This method may give rise to conflicting estimates. Fuzzy Set theory is applied to manage the situation in terms of a fuzzy conjunction to combine the various estimates. PID control was chosen because of its wide use in the industrial environment due to driving simplicity and robustness. The article shows design, development, and computer simulation aspects. 相似文献
140.
非线性地基上桩结构物空间分析 总被引:1,自引:0,他引:1
本文提出了桩结构物-非线性地基空间相互作用分析的迭代法和非线性有限元法。其中,桩基分析用p-y曲线法。结合实际结构物进行了大量的计算及比较分析,成果是令人满意的,可以付诸应用。 相似文献