全文获取类型
收费全文 | 641篇 |
免费 | 94篇 |
国内免费 | 83篇 |
专业分类
电工技术 | 29篇 |
综合类 | 99篇 |
化学工业 | 29篇 |
金属工艺 | 4篇 |
机械仪表 | 22篇 |
建筑科学 | 46篇 |
矿业工程 | 7篇 |
能源动力 | 19篇 |
轻工业 | 7篇 |
水利工程 | 11篇 |
石油天然气 | 9篇 |
武器工业 | 5篇 |
无线电 | 131篇 |
一般工业技术 | 41篇 |
冶金工业 | 15篇 |
原子能技术 | 3篇 |
自动化技术 | 341篇 |
出版年
2024年 | 3篇 |
2023年 | 13篇 |
2022年 | 23篇 |
2021年 | 31篇 |
2020年 | 35篇 |
2019年 | 37篇 |
2018年 | 26篇 |
2017年 | 37篇 |
2016年 | 42篇 |
2015年 | 40篇 |
2014年 | 70篇 |
2013年 | 57篇 |
2012年 | 46篇 |
2011年 | 49篇 |
2010年 | 30篇 |
2009年 | 39篇 |
2008年 | 38篇 |
2007年 | 42篇 |
2006年 | 31篇 |
2005年 | 32篇 |
2004年 | 22篇 |
2003年 | 19篇 |
2002年 | 13篇 |
2001年 | 9篇 |
2000年 | 4篇 |
1998年 | 9篇 |
1997年 | 1篇 |
1996年 | 2篇 |
1995年 | 4篇 |
1994年 | 2篇 |
1993年 | 3篇 |
1991年 | 2篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1987年 | 2篇 |
1985年 | 1篇 |
1971年 | 1篇 |
排序方式: 共有818条查询结果,搜索用时 15 毫秒
1.
Qin Song Zou Xubiao Zhong Yan Zhang Zhongdong 《中国炼油与石油化工》2006,(1):31-35
1 Introduction Propylene as an important feedstock for organic chemicals is mainly originated from steam cracking and catalytic cracking processes. During the FCC process the propylene content varies with the FCC catalyst and process technology adopted, resulting in significant difference in propylene concentration in the cracked product——LPG. The conventional FCC pro- cess generally gives a propylene yield of around 4%, while the FCC process with maximization of propylene yield can in… 相似文献
2.
Dodo J. Thampapillai 《国际能源研究杂志》1985,9(2):179-192
Three social objectives figure prominently in the extraction of finite energy resources, namely income maximization, environmental quality, and inter-generational concern. Owing to lack of complementarity, the pursuit of these objectives often results in conflicts. As a result, extraction strategies should be based on the determination of trade-offs between the objectives. The paper deals with the formulation and illustration of a systems model to determine these trade-offs. The recognition of such trade-offs results in a greater conservation of the finite energy resource, and hence could act as an incentive for the development of alternative energy sources. 相似文献
3.
V. V. Semenov 《Cybernetics and Systems Analysis》2007,43(2):246-252
For infinitely dimensional convex vector maximization problems, it is proved that there exists, under certain conditions,
an arbitrarily small additive perturbation of the performance criterion by a linear continuous operator such that the perturbed
problem has efficient solutions.
The study was sponsored by the Ukrainian State Fund for Basic Research
__________
Translated from Kibernetika i Sistemnyi Analiz, No. 2, pp. 105–114, March–April 2007. 相似文献
4.
R. Kamimura 《Algorithmica》1998,22(1-2):173-197
5.
6.
《Expert systems with applications》2014,41(6):2957-2963
In this paper, we consider interactive fuzzy programming for multi-level 0–1 programming problems involving random variable coefficients both in objective functions and constraints. Following the probability maximization model together with the concept of chance constraints, the formulated stochastic multi-level 0–1 programming problems are transformed into deterministic ones. Taking into account vagueness of judgments of the decision makers, we present interactive fuzzy programming. In the proposed interactive method, after determining the fuzzy goals of the decision makers at all levels, a satisfactory solution is derived efficiently by updating satisfactory levels of the decision makers with considerations of overall satisfactory balance among all levels. For solving the transformed deterministic problems efficiently, we also introduce novel tabu search for general 0–1 programming problems. A numerical example for a three-level 0–1 programming problem is provided to illustrate the proposed method. 相似文献
7.
吴胜杰 《山东电力高等专科学校学报》2010,13(3):74-76
收入分配改革是社会主义和谐社会建设的重要保障。进行收入分配体制改革攻坚是完善社会主义市场经济体制和构建主义和谐社会的重要内容。本文从库兹涅茨的倒U字型顶点区界定、收入分配改革的社会诱因以及历史背景方面对收入分配改革的启动寻找理论依据,以形成国民收入分配格局调整阶段的理论基础。 相似文献
8.
Joint bandwidth and power allocation for a multi-radio access(MRA)system in a heterogeneous wireless access environment is studied.Since both the number of users being served by the system and the wireless channel state are time-varying,the optimal resource allocation is no longer a static optimum and will change with the varying network state.Moreover,distributed resource allocation algorithms that require iterative updating and signaling interactions cannot converge in negligible time.Thus,it is unrealistic to assume that the active user number and the wireless channel state remain unchanged during the iterations.In this paper,we propose an adaptive joint bandwidth and power allocation algorithm based on a novel iteration stepsize selection method,which can adapt to the varying network state and accelerate the convergence rate.A distributed solution is also designed for the adaptive joint resource allocation implementation.Numerical results show that the proposed algorithm can not only track the varying optimal resource allocation result much more quickly than a traditional algorithm with fixed iteration stepsize,but can also reduce the data transmission time for users and increase the system throughput. 相似文献
9.
Software systems can be represented as complex networks and their artificial nature can be investigated with approaches developed in network analysis.Influence maximization has been successfully applied on software networks to identify the important nodes that have the maximum influence on the other parts.However,research is open to study the effects of network fabric on the influence behavior of the highly influential nodes.In this paper,we construct class dependence graph(CDG)networks based on eight practical Java software systems,and apply the procedure of influence maximization to study empirically the correlations between the characteristics of maximum influence and the degree distributions in the software networks.We demonstrate that the artificial nature of CDG networks is reflected partly from the scale free behavior:the in-degree distribution follows power law,and the out-degree distribution is lognormal.For the influence behavior,the expected influence spread of the maximum influence set identified by the greedy method correlates significantly with the degree distributions.In addition,the identified influence set contains influential classes that are complex in both the number of methods and the lines of code(LOC).For the applications in software engineering,the results provide possibilities of new approaches in designing optimization procedures of software systems. 相似文献
10.
In this paper, the decentralized transceivers and corresponding channel state information (CSI) signaling concepts are proposed for weighted sum rate (WSR) maximization, via linear downlink transceiver" optimization in multi-relay aided multiuser multiple-input multiple-output (MIMO) networks. Three decentral- ized algorithms are proposed with the local CSI requirements at the base station (BS) and the relay nodes. In the first proposed algorithm, the generalized channel inversion precoding is used at the BS to avoid the second hop channel sharing requirements among the relay nodes, and decentralized transceiver optimization of the relay nodes and users are developed to maximize the WSR. A minimum mean square error (MMSE)-based enhanced method is proposed as well. To further improve the performance, we provide a novel structure of the precoding matrix of the BS. The decentralized joint BS, relay and user transceiver optimization problem is formulated and solved. Also, the CSI signaling and decentralized processing in the time division duplex (TDD) system are analyzed. Simulation results show the effectiveness of the decentralized transceiver design compared to the existing algorithms. 相似文献