全文获取类型
收费全文 | 6826篇 |
免费 | 252篇 |
国内免费 | 318篇 |
专业分类
化学 | 7105篇 |
晶体学 | 2篇 |
力学 | 101篇 |
综合类 | 11篇 |
数学 | 13篇 |
物理学 | 164篇 |
出版年
2023年 | 55篇 |
2022年 | 92篇 |
2021年 | 106篇 |
2020年 | 122篇 |
2019年 | 123篇 |
2018年 | 86篇 |
2017年 | 121篇 |
2016年 | 150篇 |
2015年 | 162篇 |
2014年 | 142篇 |
2013年 | 216篇 |
2012年 | 302篇 |
2011年 | 300篇 |
2010年 | 310篇 |
2009年 | 372篇 |
2008年 | 299篇 |
2007年 | 316篇 |
2006年 | 439篇 |
2005年 | 616篇 |
2004年 | 399篇 |
2003年 | 330篇 |
2002年 | 185篇 |
2001年 | 125篇 |
2000年 | 152篇 |
1999年 | 157篇 |
1998年 | 138篇 |
1997年 | 152篇 |
1996年 | 140篇 |
1995年 | 124篇 |
1994年 | 91篇 |
1993年 | 80篇 |
1992年 | 92篇 |
1991年 | 85篇 |
1990年 | 91篇 |
1989年 | 71篇 |
1988年 | 92篇 |
1987年 | 68篇 |
1986年 | 57篇 |
1985年 | 50篇 |
1984年 | 69篇 |
1983年 | 50篇 |
1982年 | 78篇 |
1981年 | 60篇 |
1980年 | 41篇 |
1979年 | 62篇 |
1978年 | 28篇 |
排序方式: 共有7396条查询结果,搜索用时 0 毫秒
1.
Triazines are widely used in agriculture around the world as selective pre‐ and post‐emergence herbicides for the control of broad leaf and grassy weeds. With high toxicity and persistence, triazines can contaminate the environment and crops, so the development of rapid and sensitive methods for the determination of different triazines is necessary. Capillary electrophoresis comprises a group of techniques used to separate chemical mixtures. Analytical separation is based on different electrophoretic mobilities. This review focuses on the analysis of triazine herbicides with different modes of capillary electrophoresis, including capillary zone electrophoresis, micellar electrokinetic capillary electrophoresis, capillary electrochromatography and nonaqueous capillary electrophoresis. Determinations of triazines in various matrices such as surface water, groundwater, vegetables, soil and grains are emphasized. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
2.
3.
V.B. Fainerman V.N. Kazakov S.V. Lylyk A.V. Makievski R. Miller 《Colloids and surfaces. A, Physicochemical and engineering aspects》2004,250(1-3):97-102
One of the essential differences in the design of bubble pressure tensiometers consists in the geometry of the measuring capillaries. To reach extremely short adsorption times of milliseconds and below, the so-called deadtime of the capillaries must be of the order of some 10 ms. In particular, for concentrated surfactant solutions, such as micellar solutions, short deadtimes are needed to minimize the initial surfactant load of the generated bubbles. A theoretical model is derived and confirmed by experiments performed for a wide range of experimental conditions, mainly in respect to variations in deadtime and bubble volume. 相似文献
4.
Becky Lavi Abraham Marmur 《Colloids and surfaces. A, Physicochemical and engineering aspects》2004,250(1-3):409-414
An equation for the kinetics of partial drop spreading is proposed. This equation was empirically derived from experimental data for the spreading kinetics of partially wetting liquids in terms of the wet area versus time. The equation has the form of an exponential power law (EPL), and transforms into the well-known power law for complete wetting, when the equilibrium contact angle approaches zero. The EPL fits very well available experimental data. To lend additional support to the validity of this generalized equation, it will be demonstrated that when it is transformed to present the dynamic contact angle (DCA), it fits very well DCA experimental data for other wetting processes, such as capillary flow and tape coating. 相似文献
5.
The content of residual monomers is one of the most important characteristics of polymer dispersions. As a result of the similar physicochemical parameters of ethyl acrylate and methyl methacrylate, it is very difficult to determine the residual monomers in acrylate dispersions obtained by emulsion polymerization of both monomers. Gas chromatography with capillary columns, however, permits separation of these monomers and their quantitative determination in acrylate dispersions. 相似文献
6.
7.
8.
Ansgar Jüngel 《Mathematische Nachrichten》1997,185(1):85-110
A multi-dimensional transient drift-diffusion model for (at most) three charged particles, consisting of the continuity equations for the concentrations of the species and the Poisson equation for the electric potential, is considered. The diffusion terms depend on the concentrations. Such a system arises in electrophoretic modeling of three species (neutrally, positively and negatively charged) and in semiconductor theory for two species (positively charged holes and negatively charged electrons). Diffusion terms of degenerate type are also possible in semiconductor modeling. For the initial boundary value problem with mixed Dirichlet - Neumann boundary conditions and general reaction rates, a global existence result is proved. Uniqueness of solutions follows in the Dirichlet boundary case if the diffusion terms are uniformly parabolic or if the initial and boundary densities are strictly positive. Finally, we prove that solutions exist which are positive uniformly in time and globally bounded if the reaction rates satisfy appropriate growth conditions. 相似文献
9.
10.