首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   17154篇
  免费   1336篇
  国内免费   1596篇
化学   1029篇
晶体学   30篇
力学   863篇
综合类   331篇
数学   15447篇
物理学   2386篇
  2024年   26篇
  2023年   165篇
  2022年   242篇
  2021年   279篇
  2020年   393篇
  2019年   432篇
  2018年   370篇
  2017年   496篇
  2016年   488篇
  2015年   364篇
  2014年   761篇
  2013年   1360篇
  2012年   725篇
  2011年   900篇
  2010年   847篇
  2009年   1083篇
  2008年   1198篇
  2007年   1188篇
  2006年   1042篇
  2005年   955篇
  2004年   814篇
  2003年   793篇
  2002年   677篇
  2001年   574篇
  2000年   528篇
  1999年   493篇
  1998年   483篇
  1997年   439篇
  1996年   336篇
  1995年   216篇
  1994年   189篇
  1993年   139篇
  1992年   108篇
  1991年   119篇
  1990年   93篇
  1989年   67篇
  1988年   67篇
  1987年   48篇
  1986年   52篇
  1985年   80篇
  1984年   64篇
  1983年   56篇
  1982年   53篇
  1981年   57篇
  1980年   47篇
  1979年   51篇
  1978年   47篇
  1977年   23篇
  1976年   21篇
  1974年   9篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
111.
We study the mean square of the error term of the mean value for binary Egyptian fractions.We get an asymptotic formula under the Riemann Hypothesis.  相似文献   
112.
By means of the Monte Carlo sampling technique the equilibrium thermodynamics of fluids and magnets can be calculated numerically. We show that the questions of convergence and accuracy of this method can be understood in terms of the dynamics of the appropriate stochastic model. Also, we discuss to what extent various choices of transition probabilities lead to different dynamic properties of the system. As examples of applications, we consider Ising and Heisenberg spin systems. The numerical results about the dynamic correlation functions are compared to simple approximations taken from the theory of the kinetic Ising model.  相似文献   
113.
It is shown that if the ‘mean excitation energy’ assumption is introduced in the Brillouin-Wigner perturbation series, then the resulting series can be exactly summed. The implications of the result for calculating energy shift and for constructing trial functions are examined with special reference to the ground state of the helium atom.  相似文献   
114.
We estimate the difference for bounded functions h: ℝ → ℝ satisfying the Lipschitz condition, where Z v = B v −1 i=0 v i X i and with discount factor ν such that 0 < ν < 1. Here {X n , n ≥ 0} is a sequence of strongly mixing random variables with , and N is a standard normal random variable. In a particular case, the obtained upper bounds are of order O((1 − ν)1/2). Published in Lietuvos Matematikos Rinkinys, Vol. 47, No. 3, pp. 399–409, July–September, 2007. The research was partially supported by the Lithuanian State Science and Studies Foundation, grant No. T-15/07.  相似文献   
115.
建立了中立型随机微分时滞方程的LaSalle不变原理,然后应用LaSalle不变原理讨论了不确定中立型随机时滞系统的随机渐近稳定和几乎必然指数稳定的代数判据, 同时给出示例说明结果的有效性.  相似文献   
116.
Bell’s theorem is purported to demonstrate the impossibility of a local “hidden variable” theory underpinning quantum mechanics. It relies on the well-known assumption of ‘locality’, and also on a little-examined assumption called ‘statistical independence’ (SI). Violations of this assumption have variously been thought to suggest “backward causation”, a “conspiracy” on the part of nature, or the denial of “free will”. It will be shown here that these are spurious worries, and that denial of SI simply implies nonlocal correlation between spacelike degrees of freedom. Lorentz-invariant theories in which SI does not hold are easily constructed: two are exhibited here. It is conjectured, on this basis, that quantum-mechanical phenomena may be modeled by a local theory after all. This paper is dedicated to the memory of John A. Wheeler.  相似文献   
117.
In this paper, we study the thermal properties of the inner horizon of a Kerr-Newman black hole. By adopting Damour-Ruffini method and the thin film model which is developed on the base of brick wall model suggested by ’t Hooft, we calculate the temperature and the entropy of the inner horizon of a Kerr-Newman black hole. We conclude that the temperature of inner horizon is positive and the entropy of the inner horizon is proportional to the area of the inner horizon. The cut-off factor is same as it in calculation of the entropy of the outer horizon, 90β. In addition, we write the integral and differential Bekenstein-Smarr formula as the parameters of the inner horizon. Then, we discuss that if the contribution of the inner horizon is taken into account to the total entropy of the black hole, the Nernst theorem can be satisfied. At last, We calculate the tunneling rate of the outer horizon Γ+ and the inner horizon Γ. The total tunneling rate Γ should be the product of the rates of the outer and inner horizon, Γ=Γ+⋅Γ. We find that the total tunneling rate is in agreement with the Parikh’s standard result, Γ→exp (ΔS BH ), and there is no information loss.  相似文献   
118.
119.
We give a complete discussion of the C or analytic regularity of blow-up curves for Cauchy problems or some mixed problems for the Liouville equation in one space dimension. In the case of mixed problems, the regularity results depend on the boundary condition: actually, we show the existence of a sequence of boundary conditions for which the regularity of the blow-up curve is better than in the general case.  相似文献   
120.
风险企业的委托-代理模型   总被引:4,自引:0,他引:4  
传统的委托—代理理论在解释风险企业家的行为时遇到了困难。通过对传统的委托—代理理论进行重新构造和拓展,本提出逆反努力法则,验证了隐藏行动的道德风险的存在,并通过Newton迭代法和图形学方法对风险企业家的长期努力水平进行计算,发现努力水平对努力效应指数n表现出协同效应。  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号