全文获取类型
收费全文 | 16543篇 |
免费 | 1371篇 |
国内免费 | 545篇 |
专业分类
化学 | 3687篇 |
晶体学 | 71篇 |
力学 | 6735篇 |
综合类 | 86篇 |
数学 | 2523篇 |
物理学 | 5357篇 |
出版年
2024年 | 22篇 |
2023年 | 158篇 |
2022年 | 270篇 |
2021年 | 319篇 |
2020年 | 411篇 |
2019年 | 326篇 |
2018年 | 366篇 |
2017年 | 408篇 |
2016年 | 439篇 |
2015年 | 493篇 |
2014年 | 627篇 |
2013年 | 1118篇 |
2012年 | 826篇 |
2011年 | 1061篇 |
2010年 | 778篇 |
2009年 | 976篇 |
2008年 | 932篇 |
2007年 | 981篇 |
2006年 | 837篇 |
2005年 | 728篇 |
2004年 | 731篇 |
2003年 | 629篇 |
2002年 | 554篇 |
2001年 | 413篇 |
2000年 | 413篇 |
1999年 | 367篇 |
1998年 | 367篇 |
1997年 | 359篇 |
1996年 | 330篇 |
1995年 | 280篇 |
1994年 | 265篇 |
1993年 | 245篇 |
1992年 | 229篇 |
1991年 | 177篇 |
1990年 | 170篇 |
1989年 | 134篇 |
1988年 | 133篇 |
1987年 | 89篇 |
1986年 | 93篇 |
1985年 | 90篇 |
1984年 | 74篇 |
1983年 | 40篇 |
1982年 | 89篇 |
1981年 | 31篇 |
1980年 | 16篇 |
1979年 | 11篇 |
1978年 | 15篇 |
1976年 | 8篇 |
1971年 | 6篇 |
1957年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
Plasma-assisted flow control is of high industrial interest, but practical applications at full scale require a large surface of interaction. Nanosecond pulsed Dielectric Barrier Discharge (DBD) have demonstrated promising results of flow control, but their interacting region is limited to only a few cm2. In this paper, the conditions to extend a surface nanosecond DBD are documented. It is shown that a sliding discharge regime can fully fill an inter-electrode distance of 40 mm. This discharge regime promotes the formation of two hemispheric pressure waves originating from both air-exposed electrodes while an horizontal region of pressure gradient is also observed. 相似文献
4.
5.
David K Bisset 《国际流体数值方法杂志》2002,39(10):961-977
Turbulent flow simulation methods based on finite differences are attractive for their simplicity, flexibility and efficiency, but not always for accuracy or stability. This paper demonstrates that a good compromise is possible with the advected grid explicit (AGE) method. Starting from the same initial field as a previous spectral DNS, AGE method simulations of a planar turbulent wake were carried out as DNS, and then at three levels of reduced resolution. The latter cases were in a sense large‐eddy simulations (LES), although no specific sub‐grid‐scale model was used. Results for the two DNS methods, including variances and power spectra, were very similar, but the AGE simulation required much less computational effort. Small‐scale information was lost in the reduced resolution runs, but large‐scale mean and instantaneous properties were reproduced quite well, with further large reductions in computational effort. Quality of results becomes more sensitive to the value chosen for one of the AGE method parameters as resolution is reduced, from which it is inferred that the numerical stability procedure controlled by the parameter is acting in part as a sub‐grid‐scale model. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
6.
托卡马克工程试验混合堆等离子体性能的等值线图分析 总被引:3,自引:3,他引:0
盛光昭 《核聚变与等离子体物理》1989,9(1):29-36
本文简要叙述托卡马克工程试验混合堆等离子体概念设计的物理基础,对等离子体性能进行了等值线图(Plasma Operation Contour)分析。根据工程试验混合堆的要求,得出一组等离子体参数。 相似文献
7.
A Garcia-Quiroz David L AzevedoE.C da Silva 《Journal of Physics and Chemistry of Solids》2002,63(10):1863-1866
Properties of oxygenated carbon nitride films have attracted the attention of physics researchers due to their magnetic and physical properties, as well as for their usefulness in the industry. The free radicals were investigated using electron paramagnetic resonance applied in the study of spin concentration due to the different mechanism of preparation of carbon nitride films by RF-discharge with different kinds of plasma. Unpaired spin concentrations, in the order of 1020 per cm3, were measured and their time recombination dependency was important in those films. The films were grown by plasma enhanced chemical vapor deposition using mixtures of hydrocarbons, N2 and O2 in different proportions. 相似文献
8.
9.
A convective flow CO laser composed of polytetrafluoroethylene discharge tubes, nickel–chromium steel components, a cupric heat exchanger and other components is described. Operating in liquid nitrogen condition, output power of 60 W has been obtained from a non-selective cavity. 相似文献
10.
介绍了车用压差式气体流量传感器的结构设计和电测电路,指出了传感器的使用范围,由实验测出了特性曲线.该仪器可检测车用发动机曲轴箱窜气量,适用于发动机不解体故障诊断. 相似文献