全文获取类型
收费全文 | 1056篇 |
免费 | 42篇 |
国内免费 | 3篇 |
专业分类
化学 | 785篇 |
晶体学 | 9篇 |
力学 | 22篇 |
数学 | 134篇 |
物理学 | 151篇 |
出版年
2023年 | 9篇 |
2022年 | 14篇 |
2021年 | 28篇 |
2020年 | 18篇 |
2019年 | 15篇 |
2018年 | 16篇 |
2017年 | 19篇 |
2016年 | 38篇 |
2015年 | 34篇 |
2014年 | 32篇 |
2013年 | 58篇 |
2012年 | 65篇 |
2011年 | 63篇 |
2010年 | 46篇 |
2009年 | 30篇 |
2008年 | 60篇 |
2007年 | 60篇 |
2006年 | 67篇 |
2005年 | 55篇 |
2004年 | 27篇 |
2003年 | 33篇 |
2002年 | 26篇 |
2001年 | 12篇 |
2000年 | 11篇 |
1999年 | 14篇 |
1998年 | 9篇 |
1997年 | 6篇 |
1996年 | 12篇 |
1995年 | 8篇 |
1994年 | 11篇 |
1993年 | 14篇 |
1992年 | 12篇 |
1991年 | 10篇 |
1990年 | 15篇 |
1989年 | 8篇 |
1988年 | 6篇 |
1986年 | 10篇 |
1985年 | 18篇 |
1984年 | 13篇 |
1983年 | 7篇 |
1982年 | 13篇 |
1981年 | 10篇 |
1980年 | 9篇 |
1979年 | 8篇 |
1978年 | 7篇 |
1977年 | 11篇 |
1976年 | 6篇 |
1974年 | 4篇 |
1973年 | 5篇 |
1969年 | 3篇 |
排序方式: 共有1101条查询结果,搜索用时 15 毫秒
71.
We report a detailed analytic and numerical study of electronic thermal conductivity in d-wave superconductors. We compare theory of the crossover at low temperatures from T dependence to T(3) dependence for increasing temperature with recent experiments on YBa(2)Cu(3)O(7) in zero magnetic field for T approximately [0.04 K,0.4 K] by Hill et al. [Phys. Rev. Lett. 92, 027001 (2004)]. Transport theory, including impurity scattering and inelastic scattering within strong-coupling superconductivity, can consistently fit the temperature dependence of the data in the lower half of the temperature regime. We discuss the conditions under which we expect power-law dependences over wide temperature intervals. 相似文献
72.
Tengel T Fex T Emtenas H Almqvist F Sethson I Kihlberg J 《Organic & biomolecular chemistry》2004,2(5):725-731
Identification of compounds from chemical libraries that bind to macromolecules by use of NMR spectroscopy has gained increasing importance during recent years. A simple methodology based on (19)F NMR spectroscopy for the screening of ligands that bind to proteins, which also provides qualitative information about relative binding strengths and the presence of multiple binding sites, is presented here. A library of fluorinated compounds was assembled and investigated for binding to the two bacterial chaperones PapD and FimC, and also to human serum albumin (HSA). It was found that library members which are bound to a target protein could be identified directly from line broadening and/or induced chemical shifts in a single, one-dimensional (19)F NMR spectrum. The results obtained for binding to PapD using (19)F NMR spectroscopy agreed well with independent studies based on surface plasmon resonance, providing support for the versatility and accuracy of the technique. When the library was titrated to a solution of PapD chemical shift and linewidth changes were observed with increasing ligand concentration, which indicated the presence of several binding sites on PapD and enabled the assessment of relative binding strengths for the different ligands. Screening by (19)F NMR spectroscopy should thus be a valuable addition to existing NMR techniques for evaluation of chemical libraries in bioorganic and medicinal chemistry. 相似文献
73.
Gly-His-Leu-Leu-Cys coated CdS quantum dots detected Cu2+ and Ag+ selectively with high sensitivity, below 0.5 microM. 相似文献
74.
Trompier F Kornak L Calas C Romanyukha A Leblanc B Mitchell CA Swartz HM Clairand I 《Radiation measurements》2007,42(6-7):1085-1088
There is an increased need for after-the-fact dosimetry because of the high risk of radiation exposures due to terrorism or accidents. In case of such an event, a method is needed to make measurements of dose in a large number of individuals rapidly and with sufficient accuracy to facilitate effective medical triage. Dosimetry based on EPR measurements of fingernails potentially could be an effective tool for this purpose. This paper presents the first operational protocols for EPR fingernail dosimetry, including guidelines for collection and storage of samples, parameters for EPR measurements, and the method of dose assessment. In a blinded test of this protocol application was carried out on nails freshly sampled and irradiated to 4 and 20 Gy; this protocol gave dose estimates with an error of less than 30%. 相似文献
75.
M. Iapaolo F. Del Frate M. Petitdidier T. Leblanc Y. Meijer K. Stebel 《Journal of Quantitative Spectroscopy & Radiative Transfer》2007,107(1):105-119
Ozone profiles retrieved from Global Ozone Monitoring Experiment (GOME, flying on ERS-2 satellite) spectra from July 1995 to June 2003 by means of 2 independent neural network (NN) schemes have been validated with ozone lidar measurements performed at different stations belonging to the network for the detection of atmospheric composition changes (NDACC). The retrieval and the whole validation have been carried out by using the performances and resources of the European project Enabling Grid for E-sciencE (EGEE) and of a local Grid at the European Space Research Institute of the European Space Agency (ESRIN/ESA). Roughly 1800 collocated profiles have been found, in tropical, mid-latitude and high-latitude regions; for each lidar station the differences between GOME and lidar profiles have been evaluated and the global performance of the proposed NN approaches has been critically discussed. The results indicate the potentialities for obtaining reliable ozone field analysis on global scale, including detailed altitude resolved trend analysis. 相似文献
76.
77.
The thermal variations of the hyperfine fields of the two iron sites (1a, 2d) of NaMnFeF6 (S.G.P321) indicate a weak magnetic coupling of the (2d) sublattice to the net magnetization, and suggest a magnetic phase transition near 32 K. The Mössbauer and magnetization data are consistent with a ferrimagnetic structure (TN=44.6 ± 0.5 K) with low-temperature compensation point. 相似文献
78.
We use Janelidze's Categorical Galois Theory to extend Brown and Ellis's higher Hopf formulae for homology of groups to arbitrary semi-abelian monadic categories. Given such a category A and a chosen Birkhoff subcategory B of A, thus we describe the Barr-Beck derived functors of the reflector of A onto B in terms of centralization of higher extensions. In case A is the category Gp of all groups and B is the category Ab of all abelian groups, this yields a new proof for Brown and Ellis's formulae. We also give explicit formulae in the cases of groups vs. k-nilpotent groups, groups vs. k-solvable groups and precrossed modules vs. crossed modules. 相似文献
79.
Neil S. Keddie Geert Bultynck Tomas Luyten Alexandra M.Z. Slawin Stuart J. Conway 《Tetrahedron: Asymmetry》2009,20(6-8):857-866
The synthesis of d-myo-inositol 1,4,5-trisphosphate (InsP3) from methyl α-d-glucopyranose, via a type 2 Ferrier rearrangement is reported. A key intermediate in this synthesis possesses orthogonal protecting groups at the 1-, 4- and 5-position, making it a versatile starting point for the synthesis of unnatural InsP3 derivatives. Biological evaluation of the synthetic InsP3 demonstrates that this compound evokes selective Ca2+ release via activation of InsP3 receptors. 相似文献
80.