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排序方式: 共有655条查询结果,搜索用时 15 毫秒
91.
In this paper, stabilization of a nonlinear bilateral teleoperation system with time delays and actuator saturation is investigated via active disturbance rejection control (ADRC). An linear extended state observer is introduced to deal with the lumped system uncertainties. Lyapunov functions are given to prove the stabilization of the closed‐loop bilateral teleoperation system. Two Phantom Premium 1.5 HighForce (HF) robot manipulators are used in experiments to demonstrate the effectiveness of the proposed method in this paper. 相似文献
92.
There are several ways that can be used to classify or compare iterative methods for nonlinear equations, for instance; order of convergence, informational efficiency, and efficiency index. In this work, we use another way, namely the basins of attraction of the method. The purpose of this study is to compare several iterative schemes for nonlinear equations. All the selected schemes are of the third-order of convergence and most of them have the same efficiency index. The comparison depends on the basins of attraction of the iterative techniques when applied on several polynomials of different degrees. As a comparison, we determine the CPU time (in seconds) needed by each scheme to obtain the basins of attraction, besides, we illustrate the area of convergence of these schemes by finding the number of convergent and divergent points in a selected range for all methods. Comparisons confirm the fact that basins of attraction differ for iterative methods of different orders, furthermore, they vary for iterative methods of the same order even if they have the same efficiency index. Consequently, this leads to the need for a new index that reflects the real efficiency of the iterative scheme instead of the commonly used efficiency index. 相似文献
93.
European elm bark beetles,Scolytus multistriatus (Marsh.), were strongly attracted to American elms,Ulmus americana L., baited with theS. multistriatus attractant, multilure, or killed by injection of the arboricide, cacodylic acid; a combination of the two treatments was most attractive. Comparisons of beetle catches on sticky bands affixed to the trees with samples of bark from the same trees showed that the number of beetles landing on cacodylic acid-treated trees was approximately 40 times greater than the number boring into them. Spraying the bark with the insecticide chlorpyrifos had no direct effect on attraction. No live bark beetle brood was found in trees that had been treated with cacodylic acid or chlorpyrifos, but trees that were only baited or left untreated (check) were attacked, killed, and colonized. We suggest that the contribution of the cacodylic acid trap tree technique to Dutch elm disease control will be enhanced by baiting treated trees with multilure and spraying their lower boles with 0.5% chlorpyrifos. This treatment will eliminate diseased and unwanted elms as potential breeding material and kill large numbers of elm bark beetles that might otherwise innoculate healthy elms with the Dutch elm disease fungus. 相似文献
94.
乔薇 《黄河水利职业技术学院学报》2009,21(4):93-96
经济波动是供给和需求这一对矛盾运动的必然结果。经济波动是以长波为基础的短经济周期叠加上去的波动形态。自市场经济产生以来,推动经济长波的力量除了在自然经济阶段已具有的3种力量外,又增加了市场竞争力,它促进了经济长波的进一步缩短。竞争力推动了创新,创新成果的形成和扩散,推动了经济结构的调整和经济结构的转换。创新的过程实际是质量发展的过程。技术创新应分为6种形态。技术创新的实质就是通过质量创新来增加使用价值和实现交换价值。 相似文献
95.
Erbilgin N Mori SR Sun JH Stein JD Owen DR Merrill LD Bolaños RC Raffa KF Montiel TM Wood DL Gillette NE 《Journal of chemical ecology》2007,33(1):131-146
Bark beetles (Coleoptera: Curculionidae, Scolytinae) have specialized feeding habits, and commonly colonize only one or a
few closely related host genera in their geographical ranges. The red turpentine beetle, Dendroctonus valens LeConte, has a broad geographic distribution in North America and exploits volatile cues from a wide variety of pines in
selecting hosts. Semiochemicals have been investigated for D. valens in North America and in its introduced range in China, yielding apparent regional differences in response to various host
volatiles. Testing volatiles as attractants for D. valens in its native and introduced ranges provides an opportunity to determine whether geographic separation promotes local adaptation
to host compounds and to explore potential behavioral divergence in native and introduced regions. Furthermore, understanding
the chemical ecology of host selection facilitates development of semiochemicals for monitoring and controlling bark beetles,
especially during the process of expansion into new geographic ranges. We investigated the responses of D. valens to various monoterpenes across a wide range of sites across North America and one site in China, and used the resulting information
to develop an optimal lure for monitoring populations of D. valens throughout its Holarctic range. Semiochemicals were selected based on previous work with D. valens: (R)-(+)-α-pinene, (S)-(−)-α-pinene, (S)-(−)-β-pinene, (S)-(+)-3-carene, a commercially available lure [1:1:1 ratio of (R)-(+)-α-pinene:(S)-(−)-β-pinene:(S)-(+)-3-carene], and a blank control. At the release rates used, (+)-3-carene was the most attractive monoterpene tested throughout
the native range in North America and introduced range in China, confirming results from Chinese studies. In addition to reporting
a more effective lure for D. valens, we present a straightforward statistical procedure for analysis of insect trap count data yielding cells with zero counts,
an outcome that is common but makes the estimation of the variance with a Generalized Linear Model unreliable because of the
variability/mean count dependency. 相似文献
96.
The use of bonded composite patches to extend the life of aging metal airframes continues to grow as air forces and airline companies operate larger fleets beyond their original design lives. The crack-slowing power of bonded composite patches is well-known; often the process can be accomplished at a few percent of the cost of replacing the damaged component. However, care must be taken in the design of repairs to multiple site fatigue and corrosion damage so the repairs in close proximity do not create additional structural problems by inducing high stresses into the area of the repair.The current paper discusses recent modeling efforts to quantify the effects of multiple bonded composite patches in close proximity. It is well-established that a single structural repair attracts load into the locally stiffened area around the patch; further, single-sided repairs induce significant bending in the skin. The paper addresses the situation when two or more structural repairs occur near each other, and illustrates with simple design rules the acceptable practices for this case. 相似文献
97.
98.
99.
In this paper, the stochastic stabilization problem for a class of Markov jumping linear systems (MJLS) subject to actuator saturation is considered. The concept of domain of attraction in mean square sense is used to analyze the closed-loop stability. When the jumping mode is available, a mode-dependent state feedback controller is developed. Otherwise, we give a less conservative approach to design the mode-independent state feedback controller. Both design procedures can be converted into a set of linear matrix inequalities (LMIs). Finally, a numerical example is provided to show the effectiveness of the techniques. 相似文献
100.
A dynamic output feedback controller design approach based on cone complementary linearisation procedure is proposed for linear time-invariant (LTI) systems with actuator saturation. First, the estimation of the domain of attraction is given. Then, a design method to find a larger estimation of the domain of attraction is presented. In the process of design, nonconvex conditions are obtained, so a cone complementary linearisation procedure is exploited to solve the nonconvex feasibility problem. Two examples are given to illustrate the efficiency of the design method. 相似文献