全文获取类型
收费全文 | 90775篇 |
免费 | 7627篇 |
国内免费 | 4085篇 |
专业分类
电工技术 | 5695篇 |
技术理论 | 2篇 |
综合类 | 5777篇 |
化学工业 | 14052篇 |
金属工艺 | 4957篇 |
机械仪表 | 5218篇 |
建筑科学 | 6738篇 |
矿业工程 | 1853篇 |
能源动力 | 2652篇 |
轻工业 | 7094篇 |
水利工程 | 1811篇 |
石油天然气 | 3877篇 |
武器工业 | 675篇 |
无线电 | 12051篇 |
一般工业技术 | 11671篇 |
冶金工业 | 4620篇 |
原子能技术 | 1029篇 |
自动化技术 | 12715篇 |
出版年
2024年 | 371篇 |
2023年 | 1371篇 |
2022年 | 2574篇 |
2021年 | 3571篇 |
2020年 | 2503篇 |
2019年 | 2110篇 |
2018年 | 2360篇 |
2017年 | 2801篇 |
2016年 | 2456篇 |
2015年 | 3398篇 |
2014年 | 4447篇 |
2013年 | 5680篇 |
2012年 | 6046篇 |
2011年 | 6757篇 |
2010年 | 5861篇 |
2009年 | 5656篇 |
2008年 | 5591篇 |
2007年 | 5355篇 |
2006年 | 5130篇 |
2005年 | 4187篇 |
2004年 | 2854篇 |
2003年 | 2356篇 |
2002年 | 2375篇 |
2001年 | 2028篇 |
2000年 | 1915篇 |
1999年 | 1943篇 |
1998年 | 1826篇 |
1997年 | 1577篇 |
1996年 | 1412篇 |
1995年 | 1185篇 |
1994年 | 925篇 |
1993年 | 762篇 |
1992年 | 608篇 |
1991年 | 462篇 |
1990年 | 385篇 |
1989年 | 299篇 |
1988年 | 253篇 |
1987年 | 182篇 |
1986年 | 152篇 |
1985年 | 139篇 |
1984年 | 100篇 |
1983年 | 75篇 |
1982年 | 68篇 |
1981年 | 59篇 |
1980年 | 51篇 |
1979年 | 35篇 |
1978年 | 32篇 |
1977年 | 32篇 |
1976年 | 54篇 |
1973年 | 21篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
951.
The main objective of this paper is to propose an approach within the AHP framework for tackling the uncertainty and imprecision of service evaluations during pre-negotiation stages, where the expert’s comparison judgments are represented as fuzzy triangular numbers. A fuzzy prioritization method, which derives crisp priorities from consistent and inconsistent fuzzy comparison matrices, is described. The fuzzy analytic hierarchy process (FAHP)-based decision-making method can provide decision makers or buyer a valuable reference for evaluating software quality. A case study demonstrates the effectiveness of the proposed scheme. Importantly, the proposed scheme can assist decision makers in assessing the feasibility of digital video recorder system to management public space, making it highly applicable for academic and commercial purposes. 相似文献
952.
953.
954.
955.
956.
957.
958.
We present a new manifold learning algorithm called Local Orthogonality Preserving Alignment (LOPA). Our algorithm is inspired by the Local Tangent Space Alignment (LTSA) method that aims to align multiple local neighborhoods into a global coordinate system using affine transformations. However, LTSA often fails to preserve original geometric quantities such as distances and angles. Although an iterative alignment procedure for preserving orthogonality was suggested by the authors of LTSA, neither the corresponding initialization nor the experiments were given. Procrustes Subspaces Alignment (PSA) implements the orthogonality preserving idea by estimating each rotation transformation separately with simulated annealing. However, the optimization in PSA is complicated and multiple separated local rotations may produce globally contradictive results. To address these difficulties, we first use the pseudo-inverse trick of LTSA to represent each local orthogonal transformation with the unified global coordinates. Second the orthogonality constraints are relaxed to be an instance of semi-definite programming (SDP). Finally a two-step iterative procedure is employed to further reduce the errors in orthogonal constraints. Extensive experiments show that LOPA can faithfully preserve distances, angles, inner products, and neighborhoods of the original datasets. In comparison, the embedding performance of LOPA is better than that of PSA and comparable to that of state-of-the-art algorithms like MVU and MVE, while the runtime of LOPA is significantly faster than that of PSA, MVU and MVE. 相似文献
959.
The notion of amortisation has been integrated in quantitative bisimulations to make long-term behavioral comparisons between nondeterministic systems. In this paper, we present sound and complete proof systems for amortised strong probabilistic bisimulation and its observational congruence on a process algebra with probability and nondeterminism, and prove their soundness and completeness. Our results make it possible to reason about long-term (observable) probabilistic behaviors by syntactic manipulations. 相似文献
960.
快速建筑建模研究领域追求的目标包括模型的高精度、构建的高效率,以及对用户领域知识要求低、交互简单,而这往往互相矛盾.为解决这些问题,提出了一种基于组件的多层参数建模方法,使用概率网络描述建筑和组件的高层参数,作为友好的用户交互接口;使用规则库描述组件低层参数,指导高层参数生成低层参数;最后使用构建模板描述建筑构建过程.基于此,实现了徽派建筑自动营造系统,能较好的完成具有真实构建流程、高精度徽派建筑快速建模.实验结果证明了所提方法的实用性和有效性,且系统具有友好简单的交互方式,扩展性好,用户无论是否具备领域知识都能获得良好的用户体验. 相似文献