全文获取类型
收费全文 | 14369篇 |
免费 | 1239篇 |
国内免费 | 446篇 |
专业分类
化学 | 2721篇 |
晶体学 | 66篇 |
力学 | 6731篇 |
综合类 | 92篇 |
数学 | 2528篇 |
物理学 | 3916篇 |
出版年
2024年 | 10篇 |
2023年 | 133篇 |
2022年 | 224篇 |
2021年 | 283篇 |
2020年 | 373篇 |
2019年 | 284篇 |
2018年 | 323篇 |
2017年 | 356篇 |
2016年 | 397篇 |
2015年 | 423篇 |
2014年 | 541篇 |
2013年 | 1023篇 |
2012年 | 716篇 |
2011年 | 903篇 |
2010年 | 635篇 |
2009年 | 828篇 |
2008年 | 797篇 |
2007年 | 808篇 |
2006年 | 720篇 |
2005年 | 618篇 |
2004年 | 651篇 |
2003年 | 550篇 |
2002年 | 491篇 |
2001年 | 375篇 |
2000年 | 382篇 |
1999年 | 331篇 |
1998年 | 336篇 |
1997年 | 326篇 |
1996年 | 304篇 |
1995年 | 260篇 |
1994年 | 235篇 |
1993年 | 213篇 |
1992年 | 210篇 |
1991年 | 159篇 |
1990年 | 142篇 |
1989年 | 113篇 |
1988年 | 106篇 |
1987年 | 69篇 |
1986年 | 72篇 |
1985年 | 78篇 |
1984年 | 70篇 |
1983年 | 38篇 |
1982年 | 76篇 |
1981年 | 23篇 |
1980年 | 12篇 |
1979年 | 6篇 |
1978年 | 7篇 |
1976年 | 5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 203 毫秒
51.
52.
53.
The Rio de la Plata is a large and shallow water body that discharges onto the Atlantic Ocean. The main driving forces for the river flow are the bathymetry, tides, the outflow from the Paraná and Uruguay rivers and the winds. A numerical model covering the entire river was set up with the objective of increasing our understanding of the hydrographical features and morphological dynamics in the Estuary. The simulations revealed a counter-clockwise residual circulation in the Samborombón Bay and an eastward net flow near the Uruguayan coast. The residual flow is forced by both the tides and the bathymetry. The residence time for the entire river ranges from 40 to 80 days. However, residence times above 120 days was found in the Samborombón Bay. Three corridors of flow have been identified. 相似文献
54.
本文针对一类非饱和土壤水流问题,提出了基于二次插值的特征差分格式,得到了严谨的L2模误差估计.并作了数值试验,指明方法的有效性. 相似文献
55.
Masanobu Haraguchi David F. P. Pile Toshihiro Okamoto Masuo Fukui Dmitri K. Gramotnev 《Optical Review》2006,13(4):228-230
We have numerically shown the existence of coupled wedge plasmons (CWPs) which propagates along a nano gap of a twin metal
wedge. The CWPs are formed by wedge plasmons which can interact with each other. The dispersion relations of the wavenumber,
propagation distance, and beam area of CWPs, are described and show that the characteristics of CWPs are similar to those
of wedge plasmons and of gap plasmons. We also propose a new plasmon waveguide composed of twin metal wedges with a nano gap. 相似文献
56.
We consider a multipath maximum flow problem introduced by Kishimoto (Networks 27(4)(1996)279-291). The focus is on efficient transformation from arc flows into multipath flows, where a multipath flow is a nonnegative combination of multipaths. A new algorithm that is more efficient than existing ones is proposed for the transformation. 相似文献
57.
58.
59.
In this paper, an interior point cutting plane method (IPCPM)is applied to solve optimal power flow (OPF) problems. Comparedwith the simplex cutting plane method (SCPM), the IPCPM is simpler,and efficient because of its polynomial-time characteristic.Issues in implementing IPCPM for OPF problems are addressed,including (1) how to generate cutting planes without using thesimplex tableau, (2) how to identify the basis variables inIPCPM, and (3) how to generate mixed integer cutting planes.The calculation speed of the proposed algorithm is further enhancedby utilizing the sparsity features of the OPF formulation. Numericalsimulations on IEEE 14-300-bus test systems have shown thatthe proposed method is effective. 相似文献
60.