全文获取类型
收费全文 | 7247篇 |
免费 | 361篇 |
国内免费 | 235篇 |
专业分类
电工技术 | 193篇 |
综合类 | 573篇 |
化学工业 | 350篇 |
金属工艺 | 431篇 |
机械仪表 | 1355篇 |
建筑科学 | 406篇 |
矿业工程 | 154篇 |
能源动力 | 180篇 |
轻工业 | 722篇 |
水利工程 | 154篇 |
石油天然气 | 67篇 |
武器工业 | 53篇 |
无线电 | 136篇 |
一般工业技术 | 450篇 |
冶金工业 | 997篇 |
原子能技术 | 12篇 |
自动化技术 | 1610篇 |
出版年
2024年 | 9篇 |
2023年 | 53篇 |
2022年 | 91篇 |
2021年 | 127篇 |
2020年 | 166篇 |
2019年 | 163篇 |
2018年 | 156篇 |
2017年 | 135篇 |
2016年 | 174篇 |
2015年 | 211篇 |
2014年 | 299篇 |
2013年 | 417篇 |
2012年 | 393篇 |
2011年 | 446篇 |
2010年 | 385篇 |
2009年 | 416篇 |
2008年 | 323篇 |
2007年 | 503篇 |
2006年 | 449篇 |
2005年 | 387篇 |
2004年 | 370篇 |
2003年 | 365篇 |
2002年 | 342篇 |
2001年 | 296篇 |
2000年 | 220篇 |
1999年 | 181篇 |
1998年 | 151篇 |
1997年 | 128篇 |
1996年 | 108篇 |
1995年 | 84篇 |
1994年 | 85篇 |
1993年 | 46篇 |
1992年 | 22篇 |
1991年 | 16篇 |
1990年 | 15篇 |
1989年 | 9篇 |
1988年 | 10篇 |
1987年 | 13篇 |
1986年 | 4篇 |
1985年 | 6篇 |
1984年 | 12篇 |
1983年 | 9篇 |
1982年 | 7篇 |
1980年 | 3篇 |
1979年 | 3篇 |
1966年 | 5篇 |
1963年 | 3篇 |
1959年 | 3篇 |
1958年 | 4篇 |
1954年 | 4篇 |
排序方式: 共有7843条查询结果,搜索用时 15 毫秒
1.
Some picture fuzzy Bonferroni mean operators with their application to multicriteria decision making
In this paper, we extend the Bonferroni mean (BM) operator with the picture fuzzy numbers (PFNs) to propose novel picture fuzzy aggregation operators and demonstrate their application to multicriteria decision making (MCDM). On the basis of the algebraic operational rules of PFNs and BM, we introduce some aggregation operators: the picture fuzzy Bonferroni mean, the picture fuzzy normalized weighted Bonferroni mean, and the picture fuzzy ordered weighted Bonferroni mean. Then, a new picture fuzzy MCDM method is proposed with the help of the proposed operators. Lastly, a practical application of proposed model is given to verify the developed model and related results of the proposed model is compared with the results of the existing models to indicate its applicability. 相似文献
2.
3.
4.
This study demonstrates the application of an improved Evolutionary optimization Algorithm (EA), titled Multi-Objective Complex Evolution Global Optimization Method with Principal Component Analysis and Crowding Distance Operator (MOSPD), for the hydropower reservoir operation of the Oroville–Thermalito Complex (OTC) – a crucial head-water resource for the California State Water Project (SWP). In the OTC's water-hydropower joint management study, the nonlinearity of hydropower generation and the reservoir's water elevation–storage relationship are explicitly formulated by polynomial function in order to closely match realistic situations and reduce linearization approximation errors. Comparison among different curve-fitting methods is conducted to understand the impact of the simplification of reservoir topography. In the optimization algorithm development, techniques of crowding distance and principal component analysis are implemented to improve the diversity and convergence of the optimal solutions towards and along the Pareto optimal set in the objective space. A comparative evaluation among the new algorithm MOSPD, the original Multi-Objective Complex Evolution Global Optimization Method (MOCOM), the Multi-Objective Differential Evolution method (MODE), the Multi-Objective Genetic Algorithm (MOGA), the Multi-Objective Simulated Annealing approach (MOSA), and the Multi-Objective Particle Swarm Optimization scheme (MOPSO) is conducted using the benchmark functions. The results show that best the MOSPD algorithm demonstrated the best and most consistent performance when compared with other algorithms on the test problems. The newly developed algorithm (MOSPD) is further applied to the OTC reservoir releasing problem during the snow melting season in 1998 (wet year), 2000 (normal year) and 2001 (dry year), in which the more spreading and converged non-dominated solutions of MOSPD provide decision makers with better operational alternatives for effectively and efficiently managing the OTC reservoirs in response to the different climates, especially drought, which has become more and more severe and frequent in California. 相似文献
5.
Adaptive decision making requires that contingencies between decision options and their relative assets be assessed accurately and quickly. The present research addresses the challenging notion that contingencies may be more visible from small than from large samples of observations. An algorithmic account for such a seemingly paradoxical effect is offered within a satisficing-choice framework. Accordingly, a choice is only made when the sample contingency describing the relative evaluation of the 2 options exceeds a critical threshold. Small samples, because of the high dispersion of their sampling distribution, facilitate above-threshold contingencies. Across a broad range of parameters, the resulting small-sample advantage in terms of hits is stronger than their disadvantage in false alarms. Computer simulations and experiments support the model predictions. The relative advantage of small samples is most apparent when information loss is low, when the threshold is high relative to the ecological contingency, and when the sampling process is self-truncated. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
6.
Reports an error in "Tradeoffs and Theory: The Double-Mediation Model" by Marc Scholten and Steven J. Sherman (Journal of Experimental Psychology: General, 2006 May, Vol 135[2], 237-261). This article was inadvertently printed with the incorrect title. The original title was "Tradeoffs and Conflict: The Double-Mediation Model." This title highlights the relation between tradeoffs and conflict as investigated by the authors and accounted for by their model. However, readers are asked to refer to the article by the title with which it was printed to facilitate its retrieval.. (The following abstract of the original article appeared in record 2006-06642-006.) Most theories of decision making suggest that, when options imply tradeoffs between their attributes, conflict increases as tradeoff size increases, because greater sacrifices are to be incurred in choosing one option instead of another. An alternative view is that conflict decreases as tradeoff size increases, because stronger arguments can be made for any decision. The authors propose a unified model, the double-mediation model, which combines the mediating effects of sacrifice and argumentation. Our model generally predicts an inverse U-shaped relation between tradeoff size and conflict. Results support this prediction. Also, when the decision situation increases the mediating effect of sacrifice relative to that of argumentation, the relation between tradeoff size and conflict changes in an upward direction; conversely, when the decision situation increases the mediating effect of argumentation relative to that of sacrifice, the relation changes in a downward direction. Results support these predictions as well. Commonalities and differences between our model and other formulations are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
7.
At some point in their careers, clinicians who work or consult in forensic and correctional settings will almost certainly encounter individuals who exhibit psychopathic personality features. Because of the widespread use of this disorder to inform legal and clinical decision making, psychologists should be exceedingly familiar with the relevant research literature on this topic before venturing into these settings. This article reviews the empirical bases of several clinically relevant claims and assertions regarding psychopathy and concludes that many areas of research are decidedly more equivocal in their findings than is commonly perceived. Although there is much to be gained by assessing psychopathy in various contexts, clinicians need to be cautious about drawing overzealous and empirically questionable conclusions about an important disorder that also has great potential for abuse. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
8.
基于ISO/IEC17799标准建立了一个综合的信息系统风险分析框架,并运用模糊多准则决策(FMCDM)方法计算信息安全风险,根据风险等级矩阵(RLM)对信息资产风险进行级别划分,最终建立评估信息资产相关风险的完整模型。 相似文献
9.
谐波齿轮机构在商业表格印刷机中的应用 总被引:1,自引:1,他引:0
从商业表格印刷机特殊要求出发,以某一具体机型的传动系统为例,提出采用谐波齿轮机构解决纵向套准的问题。并且分析研究了谐波齿轮机构的工作原理及其在商业表格印刷机中的使用。 相似文献
10.
交通平衡分配下的公路桥收费策略 总被引:3,自引:0,他引:3
假定一个城市被一条河流分为两部分(如我国的武汉,重庆等市),河上至少架设了两座公路桥梁,本文研究在交通平衡状态下,怎样制定车辆过桥梁的收费水平,使获得的总收入最大,乘客的总行驶时间最少,对多车种问题,研究了等价的数学模型和算法。还对一个含两座桥梁与三种车型的简单算例,进行了计算与分析。 相似文献