全文获取类型
收费全文 | 1079篇 |
免费 | 50篇 |
国内免费 | 6篇 |
专业分类
化学 | 682篇 |
晶体学 | 2篇 |
力学 | 40篇 |
数学 | 195篇 |
物理学 | 216篇 |
出版年
2023年 | 11篇 |
2022年 | 13篇 |
2021年 | 38篇 |
2020年 | 26篇 |
2019年 | 20篇 |
2018年 | 17篇 |
2017年 | 25篇 |
2016年 | 49篇 |
2015年 | 40篇 |
2014年 | 47篇 |
2013年 | 57篇 |
2012年 | 58篇 |
2011年 | 75篇 |
2010年 | 30篇 |
2009年 | 36篇 |
2008年 | 63篇 |
2007年 | 67篇 |
2006年 | 75篇 |
2005年 | 56篇 |
2004年 | 43篇 |
2003年 | 31篇 |
2002年 | 35篇 |
2001年 | 14篇 |
2000年 | 14篇 |
1999年 | 13篇 |
1998年 | 12篇 |
1997年 | 8篇 |
1996年 | 7篇 |
1995年 | 7篇 |
1994年 | 6篇 |
1993年 | 6篇 |
1992年 | 7篇 |
1991年 | 4篇 |
1990年 | 4篇 |
1989年 | 13篇 |
1988年 | 5篇 |
1987年 | 8篇 |
1986年 | 10篇 |
1985年 | 9篇 |
1984年 | 12篇 |
1983年 | 4篇 |
1981年 | 7篇 |
1980年 | 11篇 |
1979年 | 9篇 |
1978年 | 4篇 |
1977年 | 5篇 |
1976年 | 6篇 |
1975年 | 3篇 |
1974年 | 4篇 |
1972年 | 2篇 |
排序方式: 共有1135条查询结果,搜索用时 46 毫秒
111.
Plasma treatments in Radio Frequency Glow Discharges fed with NH3−H2 mixtures have been performed for modifying polyethylene surfaces. Treatment kinetics and the role of species present in the
glow have been investigated. Actinometric Optical Emission Spectroscopy has been utilized as a plasma diagnostic technique.
Electron Spectroscopy for Chemical Analysis has been utilized for studying surface composition of treated substrates, which
have been examined both astreated and after derivatization of amine-functionalities with 4-trifluoromethylbenzaldehyde vapors.
It has been found that experimental plasma parameters and plasma density of active species can be controlled to achieve selective
grafting of-NH2 among all other nitrogen-containing groups. 相似文献
112.
Riccardo Zecchina 《Pramana》2005,64(6):1161-1173
The combinatorial problem of satisfying a given set of constraints that depend on N discrete variables is a fundamental one in optimization and coding theory. Even for instances of randomly generated problems, the question “does there exist an assignment to the variables that satisfies all constraints?” may become extraordinarily difficult to solve in some range of parameters where a glass phase sets in. We shall provide a brief review of the recent advances in the statistical mechanics approach to these satisfiability problems and show how the analytic results have helped to design a new class of message-passing algorithms — the survey propagation (SP) algorithms — that can efficiently solve some combinatorial problems considered intractable. As an application, we discuss how the packing properties of clusters of solutions in randomly generated satisfiability problems can be exploited in the design of simple lossy data compression algorithms. 相似文献
113.
Daniele Simoni Giuseppe GianniniPier Giovanni Baraldi Romeo RomagnoliMarinella Roberti Riccardo RondaninRiccardo Baruchello Giuseppina GrisoliaMarcello Rossi Danilo MirizziFrancesco Paolo Invidiata Stefania GrimaudoManlio Tolomeo 《Tetrahedron letters》2003,44(14):3005-3008
A double Suzuki cross-coupling protocol has been devised as a practical route to a variety of terphenyls. Good chemoselectivity was observed. Unsymmetrically substituted triphenylenes were also easily prepared. 相似文献
114.
The equilibrium and transport properties of interacting ad-particles on bivariate heterogeneous chains are studied by combining analytical and simulation approaches. Heterogeneity is introduced in the way of patches of shallow and deep adsorbing sites distributed in a deterministic alternating way. Adsorption isotherms and mean-square fluctuations of the surface coverage, as well as the jump and collective diffusion coefficients, are calculated for different values of lateral interactions between ad-particles and substrate heterogeneity. In addition, different elementary jump mechanisms are introduced and their influence in the coverage dependence of the collective diffusion coefficient is investigated. 相似文献
115.
116.
117.
118.
In this paper we are concerned with the adhesion of lipid tubules to a plane wall: we treat both the statics and the dynamics
of this phenomenon. Though we provide an exact solution to the equilibrium problem, our treatment of the dynamical problem
is approximate, as it is based on a simplified model, which, nevertheless allows us to obtain quantitative information about
the detachment dynamics of tubules.
Received September 1, 1997 相似文献
119.
The behavior of a cw dye laser under variation of the output coupling has been investigated. By studying the dependence of
laser threshold, output power and slope efficiency on the degree of outcoupling, numerical values for macroscopic and microscopic
laser parameters have been obtained. The macroscopic data comprise values for internal cavity losses and mode matching conditions,
the microscopic data refer to molecular parameters of the dye used, such as cross-sections for stimulated emission and triplet-triplet
absorption. 相似文献
120.
Riccardo Goldoni 《General Relativity and Gravitation》1983,15(7):691-699
We propose a bimetric machian approach to gravitation with a mathematical structure much simpler than the one of Rosen's bimetric theories. We obtain two cosmological models based on the simplest assumption that the Universe be filled of pure dust matter. One of the two cosmological models is compatible with the currently observed value of the density of dust matter, and provides an age of the Universe which is of the order of the inverse of the present Hubble parameter. One also obtains the Schwarzschild-like solution and its Newtonian limit together with the modified three Kepler laws which allow us to find that presently 0.5×10?10 (yr)?1 δ(A/A)δ 0.625×10?10 (yr)?1, a denoting the semimajor axis of the orbit of the test particle. Lastly we obtain the Newtonian limit of the theory. 相似文献