全文获取类型
收费全文 | 39228篇 |
免费 | 1423篇 |
国内免费 | 18篇 |
专业分类
化学 | 25467篇 |
晶体学 | 355篇 |
力学 | 760篇 |
数学 | 6168篇 |
物理学 | 7919篇 |
出版年
2023年 | 301篇 |
2022年 | 259篇 |
2021年 | 457篇 |
2020年 | 607篇 |
2019年 | 574篇 |
2018年 | 807篇 |
2017年 | 756篇 |
2016年 | 1476篇 |
2015年 | 1220篇 |
2014年 | 1244篇 |
2013年 | 2566篇 |
2012年 | 2597篇 |
2011年 | 2793篇 |
2010年 | 1660篇 |
2009年 | 1367篇 |
2008年 | 2244篇 |
2007年 | 2199篇 |
2006年 | 1902篇 |
2005年 | 1661篇 |
2004年 | 1384篇 |
2003年 | 1091篇 |
2002年 | 1004篇 |
2001年 | 774篇 |
2000年 | 696篇 |
1999年 | 522篇 |
1998年 | 402篇 |
1997年 | 330篇 |
1996年 | 450篇 |
1995年 | 332篇 |
1994年 | 321篇 |
1993年 | 378篇 |
1992年 | 344篇 |
1991年 | 264篇 |
1990年 | 253篇 |
1989年 | 210篇 |
1988年 | 212篇 |
1987年 | 227篇 |
1986年 | 198篇 |
1985年 | 302篇 |
1984年 | 269篇 |
1983年 | 210篇 |
1982年 | 217篇 |
1981年 | 194篇 |
1980年 | 177篇 |
1979年 | 196篇 |
1978年 | 183篇 |
1977年 | 161篇 |
1976年 | 188篇 |
1975年 | 184篇 |
1974年 | 161篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
Summary The gas chromatographic behaviour of crosslinked macroporous 2-hydroxyethyl methacrylate grafted with 2-methyloxazoline was
investigated and the range of applicability of the copolymer was assessed. Retention index values were measured on this copolymer
and compared with those obtained on the terpolymer 2-hydroxyethyl methacrylate-ethylene dimethacrylate-acrylonitrile. Rohrschneider
constants and efficiency data for selected sorbates are given. The use of this type of polymer in the separation of various
types of compounds is documented by various examples. 相似文献
52.
J. Ježek 《Czechoslovak Mathematical Journal》2004,54(1):233-246
We investigate congruences in one-element extensions of algebras in the variety generated by tournaments. 相似文献
53.
J. Mlynár J. Ongena The EFDA JET Contributions I. Duran M. Hron R. Pánek V. Petržílka F. Žáček 《Czechoslovak Journal of Physics》2004,54(3):C28
JET (Joint European Torus) is the largest tokamak in the world and the only fusion facility able to operate with Tritium, the fusion fuel, and Beryllium, the ITER first wall material. JET also features the most complete remote handling equipment for invessel maintenance. As a multinational research center, JET provides logistic experience in preparing for operation of the global facility, tokamak ITER.Experiments on JET are focused on ITER-relevant studies, in particular on detailing the operational scenarios (EL My H-modes and advanced regimes), on enhancing the heating systems, on developing diagnostics for burning plasmas etc. Pioneering real-time control techniques have been implemented that maximize performance and minimize internal disturbances of JET plasmas. In helium plasmas, ion cyclotron heating (ICRH) created fast α-particles, mimicking their populations in future burning plasmas. The recent successful Trace Tritium campaign provided important new data on fuel transport. Current enhancements on JET include a new ITER-like ELM-resilient high power ICRH antenna (7 MW) and over twenty new diagnostics that will further extend the JET scientific capabilities and push the facility even closer to the ITER parameters.A special mention is given to the involvement of the fusion experts from Association EURATOM-IPP.CR, who have been actively participating in the collective use of JET facility for more than three years. 相似文献
54.
L. Martinovič 《Few-Body Systems》2005,36(1-4):167-171
We study three problems of the light-front field theory quantized in a finite volume with fields (anti-)periodic in x−: (a) microcausality by deriving an integral representation for the discrete Pauli-Jordan function; (b) surface terms violating Poincaré algebra; (c) a LF version of the Goldstone theorem. The first two problems are resolved by careful mathematical treatment. The third one illustrates the usefulness of DLCQ as an analytical scheme. 相似文献
55.
Here we prove a limit theorem in the sense of the weak convergence of probability measures in the space of meromorphic functions
for a general Dirichlet series. The explicit form of the limit measure in this theorem is given.
Partially supported by Lithuanian Foundation of Studies and Science 相似文献
56.
In the paper the asymptotics for Dirichlet polynomials associated to certain cusp forms are obtained.
Partially supported by Lithuanian Foundation of Studies and Science 相似文献
57.
Anna Jenčová 《International Journal of Theoretical Physics》2004,43(7-8):1635-1649
We use a class of generalized relative entropies on density matrices to obtain one-parameter families of torsion-free affine connections. 相似文献
58.
L.G. Casado I. García T. Csendes V.G. Ruíz 《Journal of Optimization Theory and Applications》2003,118(1):27-43
Based on the investigation carried out in Ref. 1, this paper incorporates new studies about the properties of inclusion functions on subintervals while a branch-and-bound algorithm is solving global optimization problems. It is found that the relative place of the global minimum value within the inclusion function value of the objective function at the current interval indicates mostly whether the given interval is close to a minimizer point. This information is used in a heuristic interval rejection rule that can save a considerable amount of computation. Illustrative examples are discussed and an extended numerical study shows the advantages of the new approach. 相似文献
59.
E. García-Matres N. Stüßer M. Hofmann M. Reehuis 《The European Physical Journal B - Condensed Matter and Complex Systems》2003,32(1):35-42
The magnetic structures of Mn1-xFexWO4 with x
= 0.0, 0.16, 0.21, 0.225, 0.232, 0.24, 0.27, 0.29, and 1.0 were refined from neutron powder diffraction data. The magnetic phase
diagram could be completed in the coexistence range of different magnetic structures up to x
= 0.29. For the magnetic state at 1.5 K a commensurate antiferromagnetic structure with a propagation vector
= (±1/4, 1/2, 1/2) was found for x
⩽ 0.22 while the magnetic spins order with
= (1/2, 0, 0) for x
≥ 0.22. In the latter phase, additionally, weak magnetic reflections indexed to an incommensurate ordering with
= (- 0.214, 1/2, 0.457) occur in the diffraction pattern up to x
= 0.29 indicating the occurence of a reentrant phase. For 0.12 ⩽
x
⩽ 0.29 the low temperature phases are separated from a magnetic high temperature phase showing only magnetic reflections indexed
to a spin arrangement with
= (1/2, 0, 0). The magnetic phase diagram is discussed qualitatively considering random superexchange between the statistically distributed
Mn2+- and Fe2+-ions in the coexistence range 0.12 ⩽
x
⩽ 0.29 of different magnetic structures related to those of pure MnWO4 and FeWO4.
Received 9 October 2002 Published online 14 March 2003 相似文献
60.
Martin Vohralík 《Comptes Rendus Mathematique》2004,339(7):525-528
We consider the lowest-order Raviart–Thomas mixed finite element method for elliptic problems on simplicial meshes in two or three space dimensions. This method produces saddle-point type problems for scalar and flux unknowns. We show how to easily eliminate the flux unknowns, which implies an equivalence between this method and a particular multi-point finite volume scheme, without any approximate numerical integration. We describe the stencil of the final matrix and give sufficient conditions for its symmetry and positive definiteness. We present a numerical example illustrating the performance of the proposed method. To cite this article: M. Vohralík, C. R. Acad. Sci. Paris, Ser. I 339 (2004). 相似文献