全文获取类型
收费全文 | 38050篇 |
免费 | 3124篇 |
国内免费 | 3247篇 |
专业分类
电工技术 | 3148篇 |
技术理论 | 5篇 |
综合类 | 2449篇 |
化学工业 | 2468篇 |
金属工艺 | 300篇 |
机械仪表 | 1411篇 |
建筑科学 | 1326篇 |
矿业工程 | 188篇 |
能源动力 | 1359篇 |
轻工业 | 462篇 |
水利工程 | 272篇 |
石油天然气 | 231篇 |
武器工业 | 172篇 |
无线电 | 2711篇 |
一般工业技术 | 2970篇 |
冶金工业 | 956篇 |
原子能技术 | 150篇 |
自动化技术 | 23843篇 |
出版年
2024年 | 159篇 |
2023年 | 611篇 |
2022年 | 465篇 |
2021年 | 741篇 |
2020年 | 1028篇 |
2019年 | 1101篇 |
2018年 | 1032篇 |
2017年 | 1376篇 |
2016年 | 1497篇 |
2015年 | 1328篇 |
2014年 | 2258篇 |
2013年 | 3468篇 |
2012年 | 1819篇 |
2011年 | 2315篇 |
2010年 | 1673篇 |
2009年 | 2171篇 |
2008年 | 2166篇 |
2007年 | 2168篇 |
2006年 | 1878篇 |
2005年 | 1696篇 |
2004年 | 1431篇 |
2003年 | 1355篇 |
2002年 | 1241篇 |
2001年 | 988篇 |
2000年 | 987篇 |
1999年 | 896篇 |
1998年 | 799篇 |
1997年 | 713篇 |
1996年 | 646篇 |
1995年 | 564篇 |
1994年 | 502篇 |
1993年 | 482篇 |
1992年 | 370篇 |
1991年 | 354篇 |
1990年 | 281篇 |
1989年 | 217篇 |
1988年 | 188篇 |
1987年 | 169篇 |
1986年 | 137篇 |
1985年 | 180篇 |
1984年 | 189篇 |
1983年 | 167篇 |
1982年 | 147篇 |
1981年 | 96篇 |
1980年 | 72篇 |
1979年 | 85篇 |
1978年 | 61篇 |
1977年 | 67篇 |
1976年 | 19篇 |
1975年 | 13篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
George Weiss 《Mathematics of Control, Signals, and Systems (MCSS)》1991,4(2):193-203
We give an elementary proof of the well-known fact that shift-invariant operators onL
2[0, ∞) are represented by transfer functions which are bounded and analytic on the right open half-plane. We prove a generalization
to Banach space-valuedL
p
-functions, where 1≤p<∞. We show that the result no longer holds forp=∞.
This research was supported partially by the Weizmann Fellowship, and partially by the Air Force Office of Scientific Research
under Contract F49620-86-C-0111. 相似文献
72.
We obtain a necessary and sufficient condition for a discrete-time nonlinear system to be locally state equivalent to the nonlinear observer form. The result looks similar to the continuous counterpart except for the fact that Ad-operation is utilized instead of ad-operation. 相似文献
73.
The objective of this note is to propose a method for stabilization of structurally fixed modes in expansions of LTI dynamic systems in the scope of overlapping decentralized control design based on the expansion/contraction framework, enabling successful design for a broader class of problems than considered so far. The method is based on a judicious choice of complementary matrices in the expanded space. Numerical examples are provided to illustrate simplicity and efficiency of the proposed approach. 相似文献
74.
A constant trend towards more compact mechanical systems with higher power densities and increased thermo-mechanical loads emphasises the importance of the development of new design approaches and novel tribological systems. Ignoring this may cause a significant slow down in technological and industrial development. Tribotronics or active tribology based on adaptive performance is thought of as being critical in the implementation of smart machine concepts. Recognition of the importance of tribotronics, or active control of system loss outputs, such as those through friction and wear will have significant beneficial economic consequences as a result of the associated accelerated rate of technological progress. These smart tribotronic systems can be embedded in a great variety of machines and mechanisms. If this integration is made at the design stage, products that are more flexible, efficient and reliable can be produced. The concept of tribotronics is presented and discussed in this paper. Some illustrative examples that show the feasibility of an “active” approach are given. In addition, various possibilities already reported in literature are discussed. 相似文献
75.
The Florida Department of Transportation (FDOT) is in the process of implementing Pontis, a Bridge Management System, to provide decision support to engineers in the headquarters and district offices as they make routine policy, programming, and budgeting decisions regarding the preservation and improvement of the state’s bridges. As part of this effort, an ongoing research program is underway to adapt the system to FDOT needs as well as to advance the state of the art in several areas important to the Department. Most of the research results are organized around a new project-level decision support framework that complements and builds on Pontis’ existing network-level analysis. Specific new models include accident risk and user cost due to roadway width and alignment deficiencies; user cost of load capacity and vertical clearance restrictions, and moveable bridge openings; project-level prediction models for bridge element condition and costs; and prediction of economics of scale and scoping possibilities. The new models are built into a highly graphical spreadsheet model for decision support use. 相似文献
76.
Ali J. Koshkouei 《International Journal of Adaptive Control and Signal Processing》2008,22(9):859-874
Passivity with sliding mode control for a class of nonlinear systems with and without unknown parameters is considered in this paper. In fact, a method for deriving a nonlinear system with external disturbances to a passive system is considered. Then a passive sliding mode control is designed corresponding to a given storage function. The passivity property guarantees the system stability while sliding mode control techniques assures the robustness of the proposed controller. When the system includes unknown parameters, an appropriate updated law is obtained so that the new transformed system is passive. The passivation property of linear systems with sliding mode is also analysed. The linear and nonlinear theories are applied to a simple pendulum model and the gravity‐flow/pipeline system, respectively. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
77.
Gokhan Tur 《Machine Learning》2007,69(1):55-74
We propose three methods for extending the Boosting family of classifiers motivated by the real-life problems we have encountered. First, we propose a semisupervised learning method for exploiting the unlabeled data in Boosting. We then present a novel classification model adaptation method. The goal of adaptation is optimizing an existing model for a new target application, which is similar to the previous one but may have different classes or class distributions. Finally, we present an efficient and effective cost-sensitive classification method that extends Boosting to allow for weighted classes. We evaluated these methods for call classification in the AT&;T VoiceTone® spoken language understanding system. Our results indicate that it is possible to obtain the same classification performance by using 30% less labeled data when the unlabeled data is utilized through semisupervised learning. Using model adaptation we can achieve the same classification accuracy using less than half of the labeled data from the new application. Finally, we present significant improvements in the “important” (i.e., higher weighted) classes without a significant loss in overall performance using the proposed cost-sensitive classification method. 相似文献
78.
In this paper, we present a control methodology for a class of discrete time nonlinear systems that depend on a possibly exogenous scheduling variable. This class of systems consists of an interpolation of nonlinear dynamic equations in strict feedback form, and it may represent systems with a time-varying nonlinear structure. Moreover, this class of systems is able to represent some cases of gain scheduling control, Takagi-Sugeno fuzzy systems, as well as input-output realizations of nonlinear systems which are approximated via localized linearizations. We present two control theorems, one using what we call a “global” approach (akin to traditional backstepping), and a “local” approach, our main result, where backstepping is again used but the control law is an interpolation of local control terms. An aircraft wing rock regulation problem with varying angle of attack is used to illustrate and compare the two approaches. 相似文献
79.
Teerapong Senjuntichai Yasothorn Sapsathiarn 《Canadian Metallurgical Quarterly》2003,129(11):1330-1341
This paper considers the vertical vibrations of an elastic circular plate in a multilayered poroelastic half space. The plate is subjected to axisymmetric time–harmonic vertical loading and its response is governed by the classical thin-plate theory. The contact surface between the plate and the multilayered half space is assumed to be smooth and either fully permeable or impermeable. The half space under consideration consists of a number of layers with different thicknesses and material properties and is governed by Biot’s poroelastodynamic theory. The vertical displacement of the plate is represented by an admissible function containing a set of generalized coordinates. Contact stress and pore pressure jump are established in terms of generalized coordinates through the solution of flexibility equations based on the influence functions corresponding to vertical and pore pressure loading. Solutions for generalized coordinates are obtained by establishing the equation of motion of the plate through the application of Lagrange’s equations of motion. Selected numerical results are presented to portray the influence of various parameters on dynamic interaction between an elastic plate and a multilayered poroelastic half space. 相似文献
80.
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