全文获取类型
收费全文 | 1679篇 |
免费 | 230篇 |
国内免费 | 125篇 |
专业分类
化学 | 349篇 |
晶体学 | 7篇 |
力学 | 499篇 |
综合类 | 16篇 |
数学 | 185篇 |
物理学 | 978篇 |
出版年
2024年 | 3篇 |
2023年 | 10篇 |
2022年 | 24篇 |
2021年 | 29篇 |
2020年 | 35篇 |
2019年 | 38篇 |
2018年 | 39篇 |
2017年 | 35篇 |
2016年 | 55篇 |
2015年 | 43篇 |
2014年 | 83篇 |
2013年 | 142篇 |
2012年 | 95篇 |
2011年 | 114篇 |
2010年 | 76篇 |
2009年 | 121篇 |
2008年 | 89篇 |
2007年 | 111篇 |
2006年 | 99篇 |
2005年 | 93篇 |
2004年 | 79篇 |
2003年 | 81篇 |
2002年 | 64篇 |
2001年 | 55篇 |
2000年 | 59篇 |
1999年 | 49篇 |
1998年 | 37篇 |
1997年 | 38篇 |
1996年 | 29篇 |
1995年 | 27篇 |
1994年 | 27篇 |
1993年 | 27篇 |
1992年 | 26篇 |
1991年 | 24篇 |
1990年 | 15篇 |
1989年 | 11篇 |
1988年 | 13篇 |
1987年 | 3篇 |
1986年 | 9篇 |
1985年 | 5篇 |
1984年 | 6篇 |
1983年 | 4篇 |
1982年 | 6篇 |
1981年 | 2篇 |
1980年 | 3篇 |
1979年 | 1篇 |
排序方式: 共有2034条查询结果,搜索用时 234 毫秒
101.
本文详细论述了毛细管和二维狭缝中流过血液时的Fahraeus效应研究历史及现状,给出了迄今为止得到的全部结论,并报道了笔者对狭缝缝隙中Fahraeus效应研究的最新进展。本文所涉及的内容对于微循环的理论与应用以至有关流变学仪器的设计优化都有重要意义。 相似文献
102.
The thermal decomposition of CS2 highly diluted in Ar was studied behind reflected shock waves by monitoring time-dependent absorption profiles of S(3P) and S(1D) using atomic resonance absorption spectroscopy (ARAS). The rate coefficient of the reaction:
相似文献
103.
104.
K.A. Antonopoulos 《International Journal of Heat and Fluid Flow》1985,6(3):193-204
This paper considers laminar flow heat transfer in tube assemblies. The main interest is focused on the virtually unexplored cases of heat transfer under conditions of fully-developed flow inclined to the axes of the tubes and of purely transverse developing flow. The limiting cases of purely axial or purely transverse fully-developed flow are also examined. In all cases, the thermal boundary condition on the tubes is constant heat flux. Governing differential equations are expressed in terms of curvilinear-orthogonal coordinates and solved using finite-differences. Results are compared with available theoretical and experimental data. The effect of the transverse component of the flow on the temperature distribution is found to remain very strong even in nearly-axial flows and therefore considerably higher heat transfer coefficients are exhibited by a nearly-axial flow than a purely axial one. 相似文献
105.
Synthesis and applications of diethylstilbestrol-based molecularly imprinted polymer-coated hollow fiber tube 总被引:1,自引:0,他引:1
A novel molecularly imprinted polymer-coated polypropylene hollow fiber tube (MIP-HFT) was photoinitiated for the copolymerization of diethylstilbestrol (DES) as a template molecule, α-methacrylic acid as a functional monomer, and ethylene glycol dimethacrylate as a crosslinking agent. The characteristics and applications of the MIP-HFT were investigated. In order to compare its characteristics with those of a non-imprinted polymer-immersed hollow fiber tube, the selectivity of the MIP-HFT was investigated using dienestrol and hexestrol as the structural analogues of a DES template, and phenol and methylbenzene were taken as reference compounds. The MIP-HFT was employed in the HPLC analysis of spiked milk samples. The detection limits of the method were found to be in the range 2.5-3.3 μg L−1 for DES, dienestrol and hexestrol and the RSD% were in the range 6.4-8.9. The limits of quantitation were found to be in the range 8.7-9.4 μg L−1 in milk for DES, dienestrol and hexestrol, and their average recoveries were 83.7-90.6% in the spiked milk samples. The experimental results revealed that the MIP-HFT provides a good carrier for the selective adsorption of DES and its chemical structure analogs, and can be used for the preconcentration of these compounds in complicated samples. 相似文献
106.
In the present study, a GPU accelerated 1D space–time CESE method is developed and applied to shock tube problems with and without condensation. We have demonstrated how to implement the CESE algorithm to solve 1D shock tube problems using an older generation GPU (the NVIDIA 9800 GT) with relatively limited memory. To optimize the code performance, we used Shared Memory and solved the inter-Block boundary problem in two ways, namely the branch scheme and the overlapping scheme. The implementations of these schemes are discussed in detail and their performances are compared for the Sod shock tube problems. For the Sod problem without condensation, the speedup over an Intel CPU E7300 is 23 for the branch scheme and 41 for the overlapping scheme, respectively. While for problems with condensation, both schemes achieve higher acceleration ratios, 53 and 71, respectively. The higher speedup of the condensation case can be ascribed to the source term calculation which has a local dependence on the mesh point and the SOURCE kernel has a higher acceleration ratio. 相似文献
107.
We present in this paper a numerical scheme for incompressible Navier–Stokes equations with open and traction boundary conditions, in the framework of pressure-correction methods. A new way to enforce this type of boundary condition is proposed and provides higher pressure and velocity convergence rates in space and time than found in the present state of the art. We illustrate this result by computing some numerical and physical tests. In particular, we establish reference solutions of a laminar flow in a geometry where a bifurcation takes place and of the unsteady flow around a square cylinder. 相似文献
108.
In this work, the effect of an axial external moveable magnetic field on the output power of a CuBr laser with small-bore tube has been investigated. In all experiments, by applying an EMF along the tube axis, the laser output power has been decreased and by moving the EMF toward the cathode region, more substantial decrease of output power has been observed. The effect is more significant at a magnetic field intensity of 1100 G, Ne gas pressure of 35 Torr, frequency of 19 kHz and voltage of 3.8 kV, such that there was no laser emission when the EMF was placed around the cathode. 相似文献
109.
110.
|