全文获取类型
收费全文 | 654篇 |
免费 | 90篇 |
国内免费 | 53篇 |
专业分类
化学 | 159篇 |
力学 | 25篇 |
综合类 | 10篇 |
数学 | 266篇 |
物理学 | 337篇 |
出版年
2023年 | 9篇 |
2022年 | 13篇 |
2021年 | 24篇 |
2020年 | 27篇 |
2019年 | 23篇 |
2018年 | 29篇 |
2017年 | 18篇 |
2016年 | 23篇 |
2015年 | 19篇 |
2014年 | 30篇 |
2013年 | 78篇 |
2012年 | 29篇 |
2011年 | 41篇 |
2010年 | 30篇 |
2009年 | 42篇 |
2008年 | 36篇 |
2007年 | 47篇 |
2006年 | 38篇 |
2005年 | 16篇 |
2004年 | 23篇 |
2003年 | 21篇 |
2002年 | 19篇 |
2001年 | 22篇 |
2000年 | 21篇 |
1999年 | 16篇 |
1998年 | 18篇 |
1997年 | 9篇 |
1996年 | 12篇 |
1995年 | 5篇 |
1994年 | 4篇 |
1993年 | 8篇 |
1992年 | 3篇 |
1991年 | 4篇 |
1990年 | 3篇 |
1989年 | 8篇 |
1988年 | 3篇 |
1987年 | 2篇 |
1986年 | 4篇 |
1985年 | 3篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1978年 | 1篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1970年 | 2篇 |
1959年 | 1篇 |
排序方式: 共有797条查询结果,搜索用时 31 毫秒
191.
《Expositiones Mathematicae》2022,40(4):947-960
In this article we show that the main C*-algebras describing the canonical commutation relations of quantum physics, i.e., the Weyl and resolvent algebras, are in the class of Følner C*-algebras, a class of C*-algebras admitting a kind of finite approximations of Følner type. In particular, we show that the tracial states of the resolvent algebra are uniform locally finite dimensional. 相似文献
192.
A statistical thermodynamic model for the interpretation of the equilibria in solution is based on the principle that the representative statistical ensembles can be characterized by two types of molecular distribution, one for non-reacting systems and another for reacting ones, respectively. Non-reacting and reacting ensembles correspond at the molecular level to one or a couple of potential curves, respectively. The properties of the thermodynamic model for solutions can be set up following some rules. These concern the statistical extension of the microscopic model to the whole ensemble and the successive averaging to get a mean partition function. The mean partition function is linked to the experimental domain of concentrations, dilutions and equilibrium constants (probability space) and to that of calorimetry, chemical work, and potentiometry (thermodynamics space). The formal connection between probability and thermodynamic space and the conformity of thermal equivalent dilution with the formulations of statistical thermodynamics are also shown. 相似文献
193.
194.
We develop and test an approximate approach for canonical simulations of weakly bound atomic or molecular systems for which some degrees of freedom can be treated separately by quantum mechanics. The system chosen for testing is Kr10–H, for which the adiabatic approximation applied to separate the hydrogen degrees of freedom works reasonably well. The hydrogen atom is bound to the Kr clusters at cold temperatures and we calculate several bound states for clusters in the n=1–9 range, in the global minimum configuration. The structural character of the mixed quantum classical simulation is substantially different than the classical simulation for Kr10–H as a result of zero point energy effects. When quantum effects are included, the low temperature dynamics of Kr10–H are dominated by a significant well to well hopping about an incomplete icosahedral krypton core. 相似文献
195.
We have been studying the three-dimensional Ising model using some finite-size scaling ideas. The simulation is done by a fast microcanonical method. Here we present our results for the critical exponents and. 相似文献
196.
For classical point particles in a box with potential energy H(N)=N
–1(1/2)
ij=1
N
V(x
i,x
j) we investigate the canonical ensemble for largeN. We prove that asN the correlation functions are determined by the global minima of a certain free energy functional. Locally the distribution of particles is given by a superposition of Poisson fields. We study the particular case =[–L, L] andV(x, y)=}- cos(x–y),L}>0, }>0.References 相似文献
197.
We have examined the influence of parametric noise on the solution behavioru(t, x) of a nonlinear initial value() problem arising in cell kinetics. In terms of ensemble statistics, the eventual limiting solution mean
and variance
are well-characterized functions of the noise statistics, and
and
depend on . When noise is continuously present along the trajectory,
and
are independent of the noise statistics and . However, in their evolution toward
and
, both
u
(t, x) and
u
2
(t, x) depend on the noise and. 相似文献
198.
组合偏最小二乘回归方法在近红外光谱定量分析中的应用 总被引:3,自引:1,他引:3
针对近红外光谱数据局部效应显著,变量个数多,彼此间常存在严重的复共线性,并多与样品组分含量呈非线性关系,构建一种组合非线性偏最小二乘回归(E-S-QPLSR)方法。它采用无重复采样技术(subag-ging),从训练样本中生成若干子样,然后每个子样通过二次多项式偏最小二乘回归(QPLSR),建立其子模型,并实现对训练样本因变量的定量预测,再将它们交由线性PLS算法用于计算各子模型的组合权系数。将该法应用于80个玉米样品的水组分含量与其近红外光谱的定量关系建模,效果良好,显示出很强的学习能力,所建模型的预报性能也优于其它方法。 相似文献
199.
A. Ciach 《Journal of statistical physics》1985,40(3-4):593-606
A one-dimensional lattice gas (Ising model) of lengthL and with nearest-neighbor couplingJ is considered in a canonical ensemble with fixed number of particlesN=L/2. Exact expressions and asymptotic forms for largeL are derived for the density-density correlation function, using periodic boundary conditions, and for the density (magnetization) profile, using antisymmetric boundary conditions. The density-density correlation function,g, assumes for temperaturesT> T, withT = 2J(BlnL)–1 and forL large, the formg(x) =g
gc(x) +BL
–1 +a(x)L
–1 +O(L–2) wherex is a distance between considered lattice sites,B is known from earlier work of Lebowitz and Percus,(1b) anda(x) decays exponentially forx . For TT, the correlation function and the density profile behave differently, the latter exhibiting a step in the middle of the interface. 相似文献
200.
《Journal of the Egyptian Mathematical Society》2014,22(3):317-321
In this paper, we compute the 1-gap sequences of 1-Weierstrass points of non-hyperelliptic smooth projective curves of genus 10. Furthermore, the geometry of such points is classified as flexes, sextactic and tentactic points. Also, upper bounds for their numbers are estimated. 相似文献