全文获取类型
收费全文 | 47101篇 |
免费 | 1568篇 |
国内免费 | 27篇 |
专业分类
化学 | 29253篇 |
晶体学 | 449篇 |
力学 | 959篇 |
数学 | 7196篇 |
物理学 | 10839篇 |
出版年
2023年 | 313篇 |
2022年 | 315篇 |
2021年 | 550篇 |
2020年 | 707篇 |
2019年 | 756篇 |
2018年 | 1054篇 |
2017年 | 993篇 |
2016年 | 1767篇 |
2015年 | 1410篇 |
2014年 | 1547篇 |
2013年 | 3129篇 |
2012年 | 2964篇 |
2011年 | 3196篇 |
2010年 | 2060篇 |
2009年 | 1727篇 |
2008年 | 2692篇 |
2007年 | 2532篇 |
2006年 | 2318篇 |
2005年 | 1905篇 |
2004年 | 1606篇 |
2003年 | 1248篇 |
2002年 | 1184篇 |
2001年 | 937篇 |
2000年 | 905篇 |
1999年 | 650篇 |
1998年 | 548篇 |
1997年 | 430篇 |
1996年 | 533篇 |
1995年 | 408篇 |
1994年 | 389篇 |
1993年 | 409篇 |
1992年 | 372篇 |
1991年 | 280篇 |
1990年 | 293篇 |
1989年 | 226篇 |
1988年 | 245篇 |
1987年 | 228篇 |
1986年 | 218篇 |
1985年 | 350篇 |
1984年 | 324篇 |
1983年 | 244篇 |
1982年 | 250篇 |
1981年 | 243篇 |
1980年 | 227篇 |
1979年 | 235篇 |
1978年 | 244篇 |
1977年 | 229篇 |
1976年 | 256篇 |
1975年 | 239篇 |
1974年 | 223篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
921.
We consider overdetermined nonlinear systems of equationsF(x)=0, whereF:
n
m
,mn. For this type of systems we define weighted least square distance (WLSD) solutions, which represent an alternative to classical least squares solutions and to other solutions based on residual normas. We introduce a generalization of the classical method of Cimmino for linear systems and we prove local convergence results. We introduce a practical strategy for improving the global convergence properties of the method. Finally, numerical experiments are presented.Work supported by FAPESP (Grant 90/3724/6), FINEP, CNPq and FAEP-UNICAMP. 相似文献
922.
M. Pavičić 《International Journal of Theoretical Physics》1993,32(9):1481-1505
It is shown that an orthomodular lattice is an ortholattice in which aunique operation of bi-implication corresponds to the equality relation and that the ordering relation in the binary formulation of quantum logic as well as the operation of implication (conditional) in quantum logic are completely irrelevant for their axiomatization. The soundness and completeness theorems for the corresponding algebraic unified quantum logic are proved. A proper semantics, i.e., a representation of quantum logic, is given by means of a new YES-NO relation which might enable a proof of the finite model property and the decidability of quantum logic. A statistical YES-NO physical interpretation of the quantum logical propositions is provided. 相似文献
923.
The paper describes magic labelings of type (1,1,1) for two classes of graphs, which are obtained by a combination of vertex, edge and face labelings. 相似文献
924.
Vidmantas Bentkus Friedrich Götze Ričardas Zitikis 《Journal of Theoretical Probability》1993,6(4):727-780
LetB be a real separable Banach space and letX,X 1,X 2,...∈B denote a sequence of independent identically distributed random variables taking values inB. DenoteS n =n ?1/2(X 1+...X n ). Let π:B→R be a polynomial. We consider (truncated) Edgeworth expansions and other asymptotic expansions for the distribution function of the r.v. π(S n ) with uniform and nonuniform bounds for the remainder terms. Expansions for the density of π(S n ) and its higher order derivatives are derived as well. As an application of the general results we get expansions in the integral and local limit theorems for ω-statistics $$\omega _n^p (q)\mathop { = n^{{p \mathord{\left/ {\vphantom {p 2}} \right. \kern-\nulldelimiterspace} 2}} }\limits^\Delta \smallint _{(0,1)} \{ F_n (x) - x\} ^p q(x)dx$$ and investigate smoothness properties of their distribution functions. Herep≥2 is an even number,q: [0, 1]→[0, ∞] is a measurable weight function, andF n denotes the empirical distribution function. Roughly speaking, we show that in order to get an asymptotic expansion with remainder termO(n ?α), α<p/2, for the distribution function of the ω-statistic, it is sufficient thatq is nontrivial, i.e., mes{t∈(0, 1):q(t)≠0}>0. Expansions of arbitrary length are available provided the weight functionq is absolutely continuous and positive on an nonempty subinterval of (0, 1). Similar results hold for the density of the distribution function and its derivatives providedq satisfies certain very mild smoothness condition and is bounded away from zero. The last condition is essential since the distribution function of the ω-statistic has no density whenq is vanishing on an nonempty subinterval of (0, 1). 相似文献
925.
Y. A. Gordon V. Jakšić S. Molčanov B. Simon 《Communications in Mathematical Physics》1993,157(1):23-50
We investigate spectral properties of random Schrödinger operators H = - + n()(1 + |n|) acting onl
2(Z
d), where n are independent random variables uniformly distributed on [0, 1].Research partially supported by a Sloan Doctoral Dissertation Fellowship and NSERC under grant OGP-0007901Research partially supported by NSF grant DMS-9101716 相似文献
926.
The problem of calculation of Sturmian functions (positive energy Weinberg states) for nonlocal (exchange) interactions is considered. It is shown that the method of continued fractions proposed by Horáek and Sasakawa makes the calculation of Sturmian eigenfunctions and eigenvalues feasible even for complicated nonlocal interactions. As an example Sturmian functions and Sturmian eigenvalues for the low energy electron-hydrogen scattering in the static exchange approximation are calculated. In addition a very general proof of convergence of the method of continued fractions is presented.Dedicated to the memory of Professor Jozef Kvasnica. 相似文献
927.
P. PŘikryl F. Vodák O. Kapičková J. Drchalová R. černý 《Czechoslovak Journal of Physics》1993,43(1):63-71
The influence of the microgravity environment on solidification processes is discussed. A simple model of the solidification of a binary-alloy is presented with the chemical diffusion influenced by the gravitational field. Using the results of Mullins and Sekerka, we employ the linear theory of hydrodynamic stability to investigate the interfacial instability driving the pattern-forming processes in solidification. As a result, we estimate the characteristic size of the elements of the emerging pattern. We show that, in spite of good agreement of our result with the size of cellulae observed in experiments, the model cannot explain the changes in the patterns occurring in space environment. In conclusion we shortly discuss the possibility of adding realism to our simple model by including the effect of convection. 相似文献
928.
929.
930.