全文获取类型
收费全文 | 12632篇 |
免费 | 2089篇 |
国内免费 | 1218篇 |
专业分类
电工技术 | 1432篇 |
综合类 | 1182篇 |
化学工业 | 2249篇 |
金属工艺 | 449篇 |
机械仪表 | 1006篇 |
建筑科学 | 235篇 |
矿业工程 | 189篇 |
能源动力 | 749篇 |
轻工业 | 158篇 |
水利工程 | 187篇 |
石油天然气 | 463篇 |
武器工业 | 363篇 |
无线电 | 1580篇 |
一般工业技术 | 1600篇 |
冶金工业 | 320篇 |
原子能技术 | 98篇 |
自动化技术 | 3679篇 |
出版年
2024年 | 120篇 |
2023年 | 319篇 |
2022年 | 519篇 |
2021年 | 521篇 |
2020年 | 651篇 |
2019年 | 530篇 |
2018年 | 492篇 |
2017年 | 612篇 |
2016年 | 648篇 |
2015年 | 654篇 |
2014年 | 791篇 |
2013年 | 908篇 |
2012年 | 969篇 |
2011年 | 1069篇 |
2010年 | 743篇 |
2009年 | 795篇 |
2008年 | 661篇 |
2007年 | 800篇 |
2006年 | 662篇 |
2005年 | 527篇 |
2004年 | 412篇 |
2003年 | 407篇 |
2002年 | 335篇 |
2001年 | 263篇 |
2000年 | 263篇 |
1999年 | 185篇 |
1998年 | 183篇 |
1997年 | 153篇 |
1996年 | 132篇 |
1995年 | 104篇 |
1994年 | 109篇 |
1993年 | 57篇 |
1992年 | 77篇 |
1991年 | 51篇 |
1990年 | 44篇 |
1989年 | 32篇 |
1988年 | 23篇 |
1987年 | 24篇 |
1986年 | 16篇 |
1985年 | 13篇 |
1984年 | 20篇 |
1983年 | 14篇 |
1982年 | 13篇 |
1981年 | 8篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1974年 | 1篇 |
1951年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
21.
S. Zisekas G. Karagiannakis C. Kokkofitis M. Stoukides 《Journal of Applied Electrochemistry》2008,38(8):1143-1149
The reaction of NH3 decomposition was studied on Ag in a proton conducting double chamber cell-reactor. The proton conductor was a strontia-ceria-ytterbia
(SCY) perovskite of the form SrCe0.95Yb0.05O3−α. The reaction was studied at 350–700 °C and atmospheric total pressure. The proton transference number (PTN) was calculated
by simultaneous measurement of the imposed current and the proton flux and it was found to vary between 0.5 and 0.7. The effects
of imposed current, temperature and inlet gas composition on the reaction rate and the PTN, were examined. Although the faradaic
efficiency (Λ) remained near unity in all experiments, reaction rate enhancements (ρ) as high as 57 were achieved. An up to
90% decrease in the activation energy of the reaction was observed when protons were electrochemically “pumped” away from
the catalyst. 相似文献
22.
The temperature programmed (palladium) hydride decomposition appeared very effective method for diagnosing the extent of alloying in Pd-Pt/SiO2 catalysts. Introduction of Pt to Pd catalysts moves the TPHD peak gradually towards lower temperatures and the shift in hydride decomposition peak is accompanied by a decrease in the amount of released hydrogen. The catalysts prepared the direct redox method showed much better alloy homogeneity than the samples prepared by coimpregnation. The results of probing with other techniques, i.e. catalytic probing with hydrodechlorination of CCl2F2 and XRD, were in line with TPHD data. The catalytic probing showed the presence of synergistic effect, a clear indication of Pd-Pt mixing. XRD data of post-reaction samples showed carbon incorporation into Pd-rich phase, whereas separate Pt-rich phase did not experience any bulk carbiding. 相似文献
23.
本文研究了用金属有机物热发解法制备PLT8薄膜的工艺过程和基片对薄膜结构的影响,并且给出了铁电性能的测量结果。 相似文献
24.
采用奇异值分解设计广义系统的最优滤波器 总被引:6,自引:2,他引:4
本文讨论广义离散随机线性系统的状态估计问题,通过矩阵奇值分解,本文给出了一种设计降阶最优滤波器的实用方法,该方法同时还得到了动态系统和量测系统的干扰噪声的估计。 相似文献
25.
The decomposition of NO and of N2O over a CuZSM-5 zeolite and a Fe-mordenite, respectively, has been studied using tracer techniques. The results demonstrate the high mobility of the lattice oxygen ions in self-diffusion. They afford a possible explanation for the problem of how two extralattice oxygens located at positions remote from each other may combine to form the O2 molecules which are spontaneously desorbed in these redox reactions. They show that a portion of the lattice oxygen mixes into the O2 released on decomposition. The data also show that N18O and N2
18O undergo exchange with the catalyst oxygen under reaction conditions.On leave from Central Research Institute for Chemistry, Hungarian Academy of Sciences, H-1525 Budapest, Hungary. 相似文献
26.
27.
Yvon Maday Frédéric Magoulès 《Computer Methods in Applied Mechanics and Engineering》2007,196(8):1541-1553
In this paper an original variant of the Schwarz domain decomposition method is introduced for heterogeneous media. This method uses new optimized interface conditions specially designed to take into account the heterogeneity between the sub-domains on each sides of the interfaces. Numerical experiments illustrate the dependency of the proposed method with respect to several parameters, and confirm the robustness and efficiency of this method based on such optimized interface conditions. Several mesh partitions taking into account multiple cross points are considered in these experiments. 相似文献
28.
A method of processing complex signals in passive multi-element antenna arrays based on an analysis of the natural values of the correlation matrix of the signal is considered. By means of the method it is possible to substantially increase the output signal-to-noise ratio. An iterational process by means of which optimal estimators of both the signal and the amplitude-phase distribution may be obtained, is proposed. Theoretical estimators of the efficiency of the method are given. It is proved that, in terms of the efficiency, the approach considered in the article comes close to the technique of matched filtration. Results of statistical modeling that confirm the statistical results are presented. 相似文献
29.
B. E. Rytsar 《Cybernetics and Systems Analysis》2007,43(2):192-207
The paper considers the set-theoretical approach to the joint decomposition of systems of Boolean functions of variables specified
in different representation forms. The approach is based on the method of q-partitions of conjuncterms and concept of decomposition
clones. Theorems on joint decomposition of a system of full and partial functions are formulated. The approach is illustrated
by examples.
Parts I and II of this article are published in No. 5 (2001) and No. 1 (2002).
__________
Translated from Kibernetika i Sistemnyi Analiz, No. 2, pp. 39–58, March–April 2007. 相似文献
30.
From the principle of of the Domain Decomposition Method (DDM), we analyse the 2nd-order linear elliptic partial differential problems and link the Separated-Layers Algorithm (SLA) with DDM. The mathematical properties of SLA and numerical example are presented to obtain satisfactory computation results. For general linear differential ones, also are the structure of SLA and its characteristics discussed. 相似文献