全文获取类型
收费全文 | 15175篇 |
免费 | 633篇 |
国内免费 | 67篇 |
专业分类
化学 | 10466篇 |
晶体学 | 106篇 |
力学 | 440篇 |
数学 | 2479篇 |
物理学 | 2384篇 |
出版年
2023年 | 111篇 |
2022年 | 92篇 |
2021年 | 270篇 |
2020年 | 291篇 |
2019年 | 285篇 |
2018年 | 291篇 |
2017年 | 243篇 |
2016年 | 582篇 |
2015年 | 483篇 |
2014年 | 483篇 |
2013年 | 982篇 |
2012年 | 1026篇 |
2011年 | 1133篇 |
2010年 | 618篇 |
2009年 | 571篇 |
2008年 | 1012篇 |
2007年 | 970篇 |
2006年 | 883篇 |
2005年 | 791篇 |
2004年 | 642篇 |
2003年 | 562篇 |
2002年 | 554篇 |
2001年 | 279篇 |
2000年 | 251篇 |
1999年 | 180篇 |
1998年 | 157篇 |
1997年 | 160篇 |
1996年 | 185篇 |
1995年 | 119篇 |
1994年 | 139篇 |
1993年 | 141篇 |
1992年 | 118篇 |
1991年 | 82篇 |
1990年 | 83篇 |
1989年 | 77篇 |
1988年 | 65篇 |
1987年 | 65篇 |
1986年 | 51篇 |
1985年 | 102篇 |
1984年 | 116篇 |
1983年 | 74篇 |
1982年 | 79篇 |
1981年 | 58篇 |
1980年 | 62篇 |
1979年 | 38篇 |
1978年 | 52篇 |
1977年 | 43篇 |
1976年 | 25篇 |
1975年 | 28篇 |
1974年 | 30篇 |
排序方式: 共有10000条查询结果,搜索用时 500 毫秒
61.
This paper focuses on a new property for bankruptcy rules, calledsustainability, which requires that the agents with small enough claims be fully reimbursed. We show that the constrained equal-awards rule is the only rule that satisfies path independence and sustainability. Exploiting duality relations, we also provide a characterization of the constrained equal-losses rule, as the only one that satisfies composition and independence of residual claims (the dual property of sustainability). 相似文献
62.
Scopo del lavoro è di studiare la stabilità asintotica per le soluzioni di problemi di evoluzione astratti. Si considerano
operatori differenziali quali ilp-Laplaciano, e il poliarmonico, termini smorzanti e fortemente smorzanti, potenziali di richiamo o di sorgente.
相似文献
63.
Juan F García-Reyes Pilar Ortega-Barrales Antonio Molina-Díaz 《Analytical sciences》2007,23(4):423-428
A combined approach based on solid-phase optosensing and multicommutation principles has been applied to develop a method for the simultaneous analysis of two pharmaceuticals (naproxen and salicylic acid) in biological fluids. The multicommuted flow-through optosensor was based on direct native fluorescence measurements of both analgesics using a non-polar sorbent (C18 silica gel) as a solid sensing zone. The flow system was controlled by Java-written home-made software and designed using three-way solenoid valves for an independent automated manipulation of sample and carrier solutions. Using an optimized sampling time, the method was calibrated in the range of 1 - 25 and 5 - 200 ng mL(-1). The obtained detection limits were 0.3 and 1.3 ng mL(-1) for naproxen and salicylic acid, respectively, with RSD (%) values of better than 2% for both analytes. The proposed methodology was successfully applied to urine, serum and pharmaceutical preparations. Recovery percentages ranging from 96.1 to 104% were obtained for both analytes. 相似文献
64.
In this work we show that the energy associated to the linear three-dimensional magneto-elastic system decays polynomially to zero as time goes to infinity, provided the initial data is smooth enough. 相似文献
65.
C. Torres O. Alejos C. de Francisco J.M. Muñoz P. Hernández-Gómez 《Applied Physics A: Materials Science & Processing》2003,77(3-4):543-547
This paper describes a robust and fast fitting procedure applicable for relaxing processes that cannot be understood as a discrete sum of single processes but require an activation energy distribution. The method is based on a set of closed-form expressions that allow the computation of the relaxation parameters directly from the isochronal curves obtained experimentally. The usefulness of this method is checked by analyzing the isochronal curves given by a theoretical energy distribution and the magnetic disaccommodation spectra observed in yttrium iron garnet (YIG) samples. PACS 02.60.Ed; 75.60.Lr; 75.50.Gg 相似文献
66.
67.
Yuri Bozhkov Antonio Carlos Gilli Martins 《Journal of Mathematical Analysis and Applications》2004,294(1):334-344
It is shown that a Lie point symmetry of the Lane-Emden system is a Noether symmetry if and only if its parameters belong to the critical hyperbola. 相似文献
68.
Algebraic Formulation of Quantum Decoherence 总被引:1,自引:0,他引:1
An algebraic formalism for quantum decoherence in systems with continuous evolution spectrum is introduced. A certain subalgebra, dense in the characteristic algebra of the system, is defined in such a way that Riemann–Lebesgue theorem can be used to explain decoherence in a well defined final pointer basis. 相似文献
69.
In this paper an extension of the (r|X
p
)-medianoid on networks introduced by Hakimi (1983) is studied. In this extension the customer considers not only the distance
but some characteristics of the facilities such as store size, quality of service and parking space. A new firm wants to establishr new facilities which have to compete with thep facilities that already exist in the market. The entry firm wants to find their locations and characteristics to maximize
profits. Three different customer choice rules (binary, partially binary and proportional preferences) are considered. Some
discretization results are obtained and a resolution procedure is proposed. The problem is solved combining a global search
algorithm based on a branch and bound procedure with some combinatorial heuristics (greedy, interchange, and tabu search).
Some computational experiences are presented.
Partially supported by Ministerio de Ciencia y Tecnología (Spain) and FEDER, grant BFM2002-04525-C02-01. 相似文献
70.