全文获取类型
收费全文 | 8881篇 |
免费 | 801篇 |
国内免费 | 473篇 |
专业分类
电工技术 | 516篇 |
技术理论 | 1篇 |
综合类 | 550篇 |
化学工业 | 1378篇 |
金属工艺 | 572篇 |
机械仪表 | 449篇 |
建筑科学 | 742篇 |
矿业工程 | 424篇 |
能源动力 | 211篇 |
轻工业 | 489篇 |
水利工程 | 209篇 |
石油天然气 | 750篇 |
武器工业 | 79篇 |
无线电 | 1073篇 |
一般工业技术 | 1064篇 |
冶金工业 | 475篇 |
原子能技术 | 69篇 |
自动化技术 | 1104篇 |
出版年
2024年 | 56篇 |
2023年 | 167篇 |
2022年 | 325篇 |
2021年 | 428篇 |
2020年 | 352篇 |
2019年 | 306篇 |
2018年 | 306篇 |
2017年 | 330篇 |
2016年 | 275篇 |
2015年 | 398篇 |
2014年 | 453篇 |
2013年 | 577篇 |
2012年 | 561篇 |
2011年 | 594篇 |
2010年 | 504篇 |
2009年 | 502篇 |
2008年 | 436篇 |
2007年 | 488篇 |
2006年 | 449篇 |
2005年 | 402篇 |
2004年 | 244篇 |
2003年 | 227篇 |
2002年 | 185篇 |
2001年 | 172篇 |
2000年 | 199篇 |
1999年 | 241篇 |
1998年 | 187篇 |
1997年 | 137篇 |
1996年 | 140篇 |
1995年 | 120篇 |
1994年 | 104篇 |
1993年 | 66篇 |
1992年 | 60篇 |
1991年 | 46篇 |
1990年 | 29篇 |
1989年 | 28篇 |
1988年 | 19篇 |
1987年 | 10篇 |
1986年 | 8篇 |
1985年 | 8篇 |
1984年 | 2篇 |
1983年 | 3篇 |
1982年 | 4篇 |
1981年 | 1篇 |
1980年 | 3篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1951年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
2.
In this paper, we first re-examine the previous protocol of controlled quantum secure direct communication of Zhang et al.’s scheme, which was found insecure under two kinds of attacks, fake entangled particles attack and disentanglement attack. Then, by changing the party of the preparation of cluster states and using unitary operations, we present an improved protocol which can avoid these two kinds of attacks. Moreover, the protocol is proposed using the three-qubit partially entangled set of states. It is more efficient by only using three particles rather than four or even more to transmit one bit secret information. Given our using state is much easier to prepare for multiqubit states and our protocol needs less measurement resource, it makes this protocol more convenient from an applied point of view. 相似文献
3.
4.
5.
6.
通过工程实例及理论分析 ,对横向风振“锁住区”问题进行了探讨 ,对《建筑结构荷载规范》(GB5 0 0 0 9— 2 0 0 1 )中有关这一方面内容存在的一些问题进行了分析 ,希望对工程设计人员能有所帮助 相似文献
7.
8.
M.Y. Shen Z.B. ZhangX.L. Niu 《Computer Methods in Applied Mechanics and Engineering》2003,192(25):2703-2725
The generalized compact (GC) schemes and some of their important properties are presented. And a new way for constructing high order accuracy and high-resolution GC schemes is presented. The schemes constructed by using this way could satisfy some principles and demands prescribed in advance to ensure some desired properties to the schemes, such as the principle about suppression of the oscillations, the principle of stability, the order of accuracy and number of scheme points, etc. As two examples, a three-point third-order compact scheme and a three-point fifth-order GC scheme satisfying the principle about suppression of the oscillations and the principle of stability are described in this paper. Numerical results show that these schemes are shock-capturing. The time-dependent boundary conditions proposed by Thompson are well employed when the algorithm is applied to the Euler equations of gas dynamics. Fourier analysis shows that the resolution characteristics are spectral-like. 相似文献
9.
10.
In order to study water-gas transport processes in the gas-diffusion-layer (GDL) of a proton exchange membrane (PEM) fuel cell system, a multiphase, multiple-relaxation-time lattice Boltzmann model is presented in this work. The model is based on the mean-field diffuse interface theory and can handle the multiphase flows with large density ratios and various viscosities. By using the standard bounce back boundary condition and an approximate average scheme for the non-slip and wetting boundary walls, respectively, detailed liquid-gas transportation in the GDL, in which exact boundary condition is difficult to be implemented, can be simulated. Unlike most of lattice Boltzmann methods based on the Bhatnagar–Gross–Krook collision operator, the present model shows a viscosity-independent velocity field, which is very important in simulating multiphase flows where various viscosities coexist. We validate our model by simulating a static droplet on a wetting wall and compare with theoretical predictions. Then, we simulate a water-gas flow in the GDL of a PEM fuel cell and investigate the saturation-dependent transport properties under different conditions. The results are shown to be qualitatively consistent with the previous numerical and theoretical works. 相似文献