全文获取类型
收费全文 | 35116篇 |
免费 | 4111篇 |
国内免费 | 2790篇 |
专业分类
电工技术 | 3647篇 |
技术理论 | 1篇 |
综合类 | 5745篇 |
化学工业 | 3875篇 |
金属工艺 | 916篇 |
机械仪表 | 2032篇 |
建筑科学 | 1676篇 |
矿业工程 | 613篇 |
能源动力 | 887篇 |
轻工业 | 1204篇 |
水利工程 | 1054篇 |
石油天然气 | 1930篇 |
武器工业 | 419篇 |
无线电 | 3335篇 |
一般工业技术 | 4650篇 |
冶金工业 | 914篇 |
原子能技术 | 477篇 |
自动化技术 | 8642篇 |
出版年
2024年 | 146篇 |
2023年 | 444篇 |
2022年 | 703篇 |
2021年 | 860篇 |
2020年 | 1017篇 |
2019年 | 1046篇 |
2018年 | 1057篇 |
2017年 | 1214篇 |
2016年 | 1320篇 |
2015年 | 1258篇 |
2014年 | 1840篇 |
2013年 | 2478篇 |
2012年 | 2548篇 |
2011年 | 2502篇 |
2010年 | 1936篇 |
2009年 | 2000篇 |
2008年 | 1959篇 |
2007年 | 2158篇 |
2006年 | 2110篇 |
2005年 | 1704篇 |
2004年 | 1505篇 |
2003年 | 1352篇 |
2002年 | 1176篇 |
2001年 | 923篇 |
2000年 | 893篇 |
1999年 | 833篇 |
1998年 | 717篇 |
1997年 | 631篇 |
1996年 | 590篇 |
1995年 | 550篇 |
1994年 | 447篇 |
1993年 | 363篇 |
1992年 | 321篇 |
1991年 | 276篇 |
1990年 | 234篇 |
1989年 | 191篇 |
1988年 | 137篇 |
1987年 | 95篇 |
1986年 | 69篇 |
1985年 | 67篇 |
1984年 | 56篇 |
1983年 | 41篇 |
1982年 | 61篇 |
1981年 | 43篇 |
1980年 | 17篇 |
1979年 | 27篇 |
1978年 | 18篇 |
1977年 | 14篇 |
1964年 | 10篇 |
1959年 | 6篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
61.
We propose two new antidiffusive schemes for advection (or linear transport), one of them being a mixture of Roe’s Super-Bee
scheme and of the “Ultra-Bee” scheme. We show how to apply these schemes to treat time-dependent first order Hamilton–Jacobi–Bellman
equations with discontinuous initial data, possibly infinitely-valued. Numerical tests are proposed, in one and two space
dimensions, in order to validate the methods
AMS subject classifications. Primary 65M12, Secondary 58J47 相似文献
62.
63.
The error of solution of Cauchy problems for systems of ordinary differential equations is estimated in the case where the
input data are approximate. It is shown how to prepare a program for computing the right-hand sides of the system automatically
and simultaneously. Diagrams are presented to illustrate the efficiency of parallelization.
__________
Translated from Kibernetika i Sistemnyi Analiz, No. 2, pp. 175–182, March–April 2007. 相似文献
64.
65.
Shu‐Li Sun Jing Ma Nan Lv 《International Journal of Adaptive Control and Signal Processing》2008,22(10):932-948
Based on the optimal fusion estimation algorithm weighted by scalars in the linear minimum variance sense, a distributed optimal fusion Kalman filter weighted by scalars is presented for discrete‐time stochastic singular systems with multiple sensors and correlated noises. A cross‐covariance matrix of filtering errors between any two sensors is derived. When the noise statistical information is unknown, a distributed identification approach is presented based on correlation functions and the weighted average method. Further, a distributed self‐tuning fusion filter is given, which includes two stage fusions where the first‐stage fusion is used to identify the noise covariance and the second‐stage fusion is used to obtain the fusion state filter. A simulation verifies the effectiveness of the proposed algorithm. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
66.
A task-switching paradigm with a 2:1 mapping between cues and tasks was used to separate cue-switching processes (indexed through pure cue-switch costs) from actual task-switching processes (indexed through additional costs in case of cue and task changes). A large portion of total switch costs was due to cue changes (Experiments 1 and 2), and cue-switch costs but not task-switch costs were sensitive to effects of practice (Experiment 1) and preparation (Experiment 2). In contrast, task-switch costs were particularly sensitive to response-priming effects (Experiments 1 and 2) and task-set inhibition (Experiment 3). Results suggest two processing stages relevant during task-set selection: cue-driven retrieval of task rules from long-term memory and the automatic application of rules to a particular stimulus situation. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
67.
In this paper the response of nonlinear systems driven by parametric Poissonian white noise is examined.As is well known, the response sample function or the response statistics of a system driven by external white noise processes is completely defined. Starting from the system driven by external white noise processes, when an invertible nonlinear transformation is applied, the transformed system in the new state variable is driven by a parametric type excitation. So this latter artificial system may be used as a tool to find out the proper solution to solve systems driven by parametric white noises. In fact, solving this new system, being the nonlinear transformation invertible, we must pass from the solution of the artificial system (driven by parametric noise) to that of the original one (driven by external noise, that is known). Moreover, introducing this invertible nonlinear transformation into the Itô’s rule for the original system driven by external input, one can derive the Itô’s rule for systems driven by a parametric type excitation, directly. In this latter case one can see how natural is the presence of the Wong–Zakai correction term or the presence of the hierarchy of correction terms in the case of normal and Poissonian white noise, respectively. Direct transformation on the Fokker–Planck and on the Kolmogorov–Feller equation for the case of parametric input are found. 相似文献
68.
69.
The results are given of numerical solution of the Boltzmann equation in a binomial approximation in view of elastic and inelastic electron collisions in Xe+CH4 mixtures and in pure methane. The electron energy distribution functions obtained are used to calculate the electron transport coefficients for E/N values of up to several Townsends, i.e., the drift velocity, mobility, average and characteristic energies, diffusion coefficient. The results of calculation for pure methane fit the available experimental data. A similarity rule is found for the electron transport coefficients in a Xe+CH4 mixture with different concentrations of methane molecules, which enables one to determine the values of transport coefficients in a mixture with a minor (less than 30 percents) methane content. 相似文献
70.