全文获取类型
收费全文 | 10343篇 |
免费 | 1244篇 |
国内免费 | 1037篇 |
学科分类
数理化 | 12624篇 |
出版年
2024年 | 13篇 |
2023年 | 92篇 |
2022年 | 135篇 |
2021年 | 184篇 |
2020年 | 251篇 |
2019年 | 302篇 |
2018年 | 273篇 |
2017年 | 360篇 |
2016年 | 398篇 |
2015年 | 347篇 |
2014年 | 533篇 |
2013年 | 857篇 |
2012年 | 534篇 |
2011年 | 634篇 |
2010年 | 499篇 |
2009年 | 597篇 |
2008年 | 642篇 |
2007年 | 662篇 |
2006年 | 533篇 |
2005年 | 512篇 |
2004年 | 476篇 |
2003年 | 433篇 |
2002年 | 457篇 |
2001年 | 369篇 |
2000年 | 365篇 |
1999年 | 325篇 |
1998年 | 289篇 |
1997年 | 260篇 |
1996年 | 185篇 |
1995年 | 129篇 |
1994年 | 115篇 |
1993年 | 85篇 |
1992年 | 70篇 |
1991年 | 83篇 |
1990年 | 54篇 |
1989年 | 62篇 |
1988年 | 55篇 |
1987年 | 50篇 |
1986年 | 36篇 |
1985年 | 62篇 |
1984年 | 49篇 |
1983年 | 22篇 |
1982年 | 42篇 |
1981年 | 42篇 |
1980年 | 24篇 |
1979年 | 27篇 |
1978年 | 24篇 |
1977年 | 16篇 |
1976年 | 20篇 |
1973年 | 11篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
建立了相变热力学理论和场论的关系. 强调在量子场论中必须引进序参量场, 则相变的讨论就类似于Goldstone bosons 的产生. 如果只讨论一级相变, Goldstone bosons场就足够了; 如果要讨论二级相变, 则必须讨论一系列的场, 这些场构成一个对称群的表示. 另外, 也将这一思想用到色超导中. In this paper we built a relation between the thermodynamical theory of the phase transition and field theory. We emphasized that in the quantum field theory we have to introduce the order parameter fields. Then the discussion of the phase transition is closed to the creation of the Goldstone bosons. If we only discuss the first order transition, the Goldstone bosons fields are sufficient. If we want to discuss the second order transition, we have to discuss a set of fields that constructs a representation of a symmetry group. We also apply this concept to color superconductivity. 相似文献
32.
D. Amutha Rani Y. Yamamoto S. Mohri M. Sivakumar Y. Tsujita H. Yoshimizu 《Journal of Polymer Science.Polymer Physics》2003,41(3):269-273
In this study, a novel stepwise extraction method has been examined. The guest molecules housed between the helices of the clathrate δ form of syndiotactic polystyrene can be removed completely with this method. A systematic study of the preparation of a solvent‐free mesophase (emptied clathrate) membrane, its helical and residual solvent contents, and its structural transformations has been performed. In this first attempt, an enhancement in the TTGG helical content has been observed in the extracted membrane, and a conceptual mechanism is proposed. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 269–273, 2003 相似文献
33.
Mats Gyllenberg 《Journal of Differential Equations》2004,205(1):50-76
For time-periodic dissipative and irreducible type-K competitive Kolmogorov systems, it is proved that there is a canonically defined countable family F of unordered, disjoint invariant sets with the property that, for every persistent trajectory whose ω-limit set is not a cycle, there exists a unique trajectory in some element of F such that these two trajectories are asymptotic and the corresponding points in these two trajectories are K-related. 相似文献
34.
Vinod Kumar Pragya Das R.P. Singh S. Muralithar R.K. Bhowmik 《The European Physical Journal A - Hadrons and Nuclei》2003,17(2):153-157
The fusion evaporation reaction 122Sn(14N, 4n)132La was used to populate the high-spin states of 132La at the beam energy of 60 MeV. A new band consisting of mostly E2 transitions has been discovered. This band has the interesting links to the ground state 2- and the isomeric state 6-. A new transition of energy 351 keV connecting the low-spin states of the positive-parity band based on the πh
11/2 ⊗ νh
11/2 particle configuration, has been found. This has played a very important role in resolving the existing ambiguities and inconsistencies
in the spin assignment of the band head.
Received: 12 August 2002 / Accepted: 18 March 2003 / Published online: 7 May 2003 相似文献
35.
袁文俊 《数学物理学报(A辑)》2003,23(2):224-230
该文考虑具有控制系数 A\-0 和系数仅有有限个极点的高阶线性齐次微分方程(1.1)。得到了一个复振荡结果,该结果是J. K. Langley[11]等作者在整系数下相应结果的推广。 相似文献
36.
High-speed imaging of phenomena akin to laser lithotripsy is performed. A new method for guiding laser light for the stone destruction is proposed. This is based on a combination of signals obtained from the correlation of fluorescent and ballistic images. 相似文献
37.
38.
We obtain exponential upper bounds for tails of distributions of generalized L-statistics based on a sample from an exponential distribution. We prove the asymptotic normality of generalized L-statistics based on a sample from the uniform distribution on [0,1] and of L-statistics with decomposed kernels (without any restrictions on the sample distribution type). 相似文献
39.
40.
B. Saha S. Bhattacharyya T. K. Mukherjee P. K. Mukherjee 《International journal of quantum chemistry》2003,92(5):413-418
In the framework of nonrelativistic variational formalism a new type of basis set is proposed, to estimate separately the effect of radial and angular correlations on the ground‐state energy for helium isoelectronic sequence H? to Ar16+. Effect of radial correlation is incorporated by using multiexponential functions arising from product basis sets suitably formed out of Slater‐type one‐particle orbitals. The angular correlation can be switched on by incorporating an expansion in terms of basis involving interparticle coordinates. With a set of six‐term Slater‐type one‐particle basis and five‐term interparticle expansion, the ground‐state energy of helium is estimated as ?2.9037236 (a.u.) compared with the multiterm variational estimates ?2.9037244 (a.u.) due to Pekeris and Thakkar and Smith and Drake. Matrix elements of different operators in the ground state have been calculated and found to be in good agreement with available accurate results. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2003 相似文献