全文获取类型
收费全文 | 13076篇 |
免费 | 2287篇 |
国内免费 | 424篇 |
专业分类
化学 | 1775篇 |
晶体学 | 88篇 |
力学 | 2982篇 |
综合类 | 143篇 |
数学 | 2501篇 |
物理学 | 8298篇 |
出版年
2025年 | 68篇 |
2024年 | 269篇 |
2023年 | 313篇 |
2022年 | 276篇 |
2021年 | 340篇 |
2020年 | 448篇 |
2019年 | 367篇 |
2018年 | 391篇 |
2017年 | 449篇 |
2016年 | 450篇 |
2015年 | 376篇 |
2014年 | 773篇 |
2013年 | 733篇 |
2012年 | 752篇 |
2011年 | 853篇 |
2010年 | 708篇 |
2009年 | 697篇 |
2008年 | 765篇 |
2007年 | 750篇 |
2006年 | 714篇 |
2005年 | 670篇 |
2004年 | 627篇 |
2003年 | 580篇 |
2002年 | 447篇 |
2001年 | 424篇 |
2000年 | 354篇 |
1999年 | 300篇 |
1998年 | 293篇 |
1997年 | 231篇 |
1996年 | 197篇 |
1995年 | 184篇 |
1994年 | 131篇 |
1993年 | 138篇 |
1992年 | 120篇 |
1991年 | 119篇 |
1990年 | 82篇 |
1989年 | 77篇 |
1988年 | 66篇 |
1987年 | 53篇 |
1986年 | 27篇 |
1985年 | 29篇 |
1984年 | 30篇 |
1983年 | 17篇 |
1982年 | 26篇 |
1981年 | 20篇 |
1980年 | 11篇 |
1979年 | 12篇 |
1977年 | 5篇 |
1973年 | 7篇 |
1971年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
Hongwei Hao Minsheng Wu Yifang Chen Jiaowen Tang Qingyu Wu 《Colloids and surfaces. B, Biointerfaces》2004,33(3-4):151-156
To prevent cyanobacterial bloom in eutrophic water by ultrasonic method, ultrasonic irradiations with different parameters were tested to inhibit Spirulina platensis from growth. The experimental result based on cyanobacterial growth, chlorophyll a and photosynthetic activity showed that, the ultrasonic irradiation inhibited cyanobacterial proliferation effectively, furthermore the inhibition effectiveness increased in the order: 200 kHz>1.7 MHz>20 kHz and became saturated with the increased power. The inhibition mechanism can be mainly attributed to the mechanical damage to the cell structures caused by ultrasonic cavitation, which was confirmed by light microscopy and differential interference microscopy. The optimal frequency of 200 kHz in cavition and sonochemistry was also most effective in cyanobacterial growth inhibition. The higher frequency of 1.7 MHz is weaker than 20 kHz in cavitation, but has more effective inhibition because it is nearer to the resonance frequency of gas vesicle. The inhibition saturation with ultrasonic power was due to the ultrasonic attenuation induced by the acoustic shielding of bubbles enclosing the radiate surface of transducer. 相似文献
2.
An infinite row of periodically spaced, identical rigid circularcylinders is excited by an acoustic line source which is parallelto the generators of the cylinders. A method for calculatingthe scattered field accurately and efficiently is presented.When the cylinders are sufficiently close together, Rayleigh–Blochsurface waves that propagate energy to infinity along the arrayare excited. An expression is derived which enables the amplitudesof these surface waves to be computed without requiring thesolution to the full scattering problem. 相似文献
3.
A finite volume solver for the 2D depth‐integrated harmonic hyperbolic formulation of the mild‐slope equation for wave propagation is presented and discussed. The solver is implemented on unstructured triangular meshes and the solution methodology is based upon a Godunov‐type second‐order finite volume scheme, whereby the numerical fluxes are computed using Roe's flux function. The eigensystem of the mild‐slope equations is derived and used for the construction of Roe's matrix. A formulation that updates the unknown variables in time implicitly is presented, which produces a more accurate and reliable scheme than hitherto available. Boundary conditions for different types of boundaries are also derived. The agreement of the computed results with analytical results for a range of wave propagation/transformation problems is very good, and the model is found to be virtually paraxiality‐free. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
4.
5.
LIZHIBIN SHIHE 《高校应用数学学报(英文版)》1996,11(1):1-6
Abstract. We consider the following simplified model for the Belousou-Zhabotinskii(B-Z)reaction: 相似文献
6.
《Analytical letters》2012,45(10):723-728
Abstract A new method for the end-point detection in complexometric titration using a tensammetric wave of organic reagents such as oxine and alizarin complexone (ALC) was studied. The tensammetric wave of these reagents disappears by their chelate formation and reappears by the liberation of free indicator during the exchange reaction between indicator chelate and EDTA. This mechanism is utilized for the end-point detection in complexometric titration of metals. Since the sensitivity of tensammetric wave is extremely high, very sharp end-point can be obtained for the titration of metals even in the concentration of 10?5M. 相似文献
7.
8.
9.
Effects of a finite ion temperature on the Hall magnetohydrodynamics (MHD), which breaks down for a finite ion temperature, are clarified in terms of a rigorous three-field kinetic dispersion relation. The MHD mode equation becomes anisotropic with respect to the ion pressure because of the double adiabaticity in ion dynamics. 相似文献
10.