全文获取类型
收费全文 | 16415篇 |
免费 | 2120篇 |
国内免费 | 1085篇 |
专业分类
电工技术 | 644篇 |
技术理论 | 1篇 |
综合类 | 947篇 |
化学工业 | 2853篇 |
金属工艺 | 1753篇 |
机械仪表 | 1847篇 |
建筑科学 | 641篇 |
矿业工程 | 1459篇 |
能源动力 | 982篇 |
轻工业 | 266篇 |
水利工程 | 147篇 |
石油天然气 | 219篇 |
武器工业 | 295篇 |
无线电 | 1636篇 |
一般工业技术 | 2005篇 |
冶金工业 | 625篇 |
原子能技术 | 78篇 |
自动化技术 | 3222篇 |
出版年
2024年 | 100篇 |
2023年 | 621篇 |
2022年 | 793篇 |
2021年 | 955篇 |
2020年 | 928篇 |
2019年 | 662篇 |
2018年 | 562篇 |
2017年 | 667篇 |
2016年 | 675篇 |
2015年 | 922篇 |
2014年 | 1272篇 |
2013年 | 1371篇 |
2012年 | 2126篇 |
2011年 | 1997篇 |
2010年 | 1290篇 |
2009年 | 1162篇 |
2008年 | 556篇 |
2007年 | 790篇 |
2006年 | 609篇 |
2005年 | 234篇 |
2004年 | 101篇 |
2003年 | 99篇 |
2002年 | 134篇 |
2001年 | 89篇 |
2000年 | 84篇 |
1999年 | 80篇 |
1998年 | 65篇 |
1997年 | 44篇 |
1996年 | 52篇 |
1995年 | 53篇 |
1994年 | 63篇 |
1993年 | 44篇 |
1992年 | 45篇 |
1991年 | 30篇 |
1990年 | 26篇 |
1989年 | 23篇 |
1988年 | 37篇 |
1987年 | 75篇 |
1986年 | 87篇 |
1985年 | 28篇 |
1984年 | 11篇 |
1983年 | 10篇 |
1982年 | 10篇 |
1981年 | 11篇 |
1980年 | 3篇 |
1979年 | 6篇 |
1978年 | 6篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1951年 | 10篇 |
排序方式: 共有10000条查询结果,搜索用时 10 毫秒
41.
The multi-dimensional torus is one of the most popular underlying topologies for massively parallel systems. In this study, we consider a non-bipartite n-dimensional torus where n≥2 and prove that for 1≤m≤2n, m vertex disjoint paths exist that cover all vertices between any two distinct vertices. In other words, we construct the one-to-one m-disjoint path cover of a non-bipartite torus for any m where 1≤m≤2n. 相似文献
42.
Understanding how fuel sloshes in a fuel cell, as a vehicle races around a circuit, is an important but mostly unexplored factor when designing fuel containment systems. Cell designs are based on knowledge of how liquids slosh in other containers, with the design and placement of structures, such as weirs, based on engineering judgement.This work aims to provide better understanding for this difficult problem with a view to improve future designs. A Graphics Processing Unit (GPU) based Smoothed Particle Hydrodynamics (SPH) model is presented to simulate the fuel sloshing problem, with results from a simplified and real fuel cell geometry shown and compared against real data recorded in a vehicle. The vehicle motion and accelerations are included in the SPH simulations using a body force within the momentum equation. Results show good agreement between the simulation and the real fuel movement, with bulk motion captured well for accelerations up to 5 times gravity.Focus is placed on the practicality of the method for use as part of an industrial design process, therefore the amount of time needed to compute results is considered throughout. Computational performance is found to be within acceptable limits, while numerical accuracy is actively considered through the use of Kahan compensated summation. It is concluded that the model is successful in capturing the necessary fluid dynamics for it to be useful in fuel cell design. It is expected that the method will provide insight into current cell designs and highlight where improvements can be made. 相似文献
43.
44.
针对不一致决策表的规则获取,从属性多粒度角度考虑,按粒度由粗到细将决策表划分成不同的粒度空间,通过定义相容粒关系矩阵和不相容粒关系矩阵,并充分挖掘隐含在矩阵中的启发式信息,实现对不同粒度空间确定性规则和不确定性规则的获取.最后,从实例分析以及UCI测试对算法进行验证,并与现有算法进行实验对比,实验结果与分析表明了所提出算法的可行性和有效性,而且按此方法获取的规则集的泛化能力更强. 相似文献
45.
隧道作为路段的特殊构造物,具有易发生事故及事故危害程度大,难于处理的特点。为保障公路隧道内道路畅通和行车安全,减少交通事故的发生,防止造成二次事故,隧道需要设置交通控制系统。以青海柳梢沟隧道监控系统为例,系统通过组建ABB AC500 PLC冗余系统OPC服务器,由组态软件i FIX自带的OPC客户端驱动读取服务器数据,与工业以太网技术相结合来实现公路隧道的远程数据采集。实际运行表明,该系统操作简便、易于维护、通信稳定且数据传输速率高。 相似文献
46.
47.
48.
In this paper, a nonlinear entanglement witness criterion based on continuous-variable local orthogonal observables for bipartite states is established, which is strictly stronger than the the linear entanglement witnesses criterion introduced by Zhang et al. (Phys. Rev. Lett. 111:190501, 2013). This criterion is particularly applied to two-mode Gaussian states yielding a criterion in terms of the covariance matrix. Comparison with CCNR criterion is discussed. 相似文献
49.
Virtual screening uses computer based methods to discover new ligands on the basis of biological structures. Among all virtual screening methods structure based docking has received considerable attention. In an attempt to identify new ligands as urease inhibitors, structure-based virtual screening (SBVS) of an in-house database of 10,000 organic compounds was carried out. The X-ray crystallographic structure of Bacillus pasteurii (BP) in complex with acetohydroxamic acid (PDB Code 4UBP) was used as a protein structure. As a starting point, ~10,000 compounds of our in-house database were analyzed to check redundancy and the compounds found repeated were removed from the database. Finally 6993 compounds were docked into the active site of BP urease using GOLD and MOE-Dock software. A remarkable feature of this study was the identification of monastrol, a well-known KSP inhibitor already in clinical trials, as a novel urease inhibitor. The hits identified were further evaluated by molecular docking and on examination of the affinity predictions, twenty-seven analogs of monastrol were synthesized by a multicomponent Biginelli reaction followed by their in vitro screening as urease inhibitors. Finally twelve compounds were identified as new urease inhibitors. The excellent in vitro activity suggested that these compounds may serve as viable lead compounds for the treatment of urease related problems. 相似文献
50.
Concurrence for infinite-dimensional quantum systems 总被引:1,自引:0,他引:1
Concurrence is an important entanglement measure for states in finite-dimensional quantum systems that was explored intensively in the last decade. In this paper, we extend the concept of concurrence to infinite-dimensional bipartite systems and show that it is continuous and does not increase under local operation and classical communication. 相似文献