全文获取类型
收费全文 | 304篇 |
免费 | 0篇 |
国内免费 | 5篇 |
专业分类
化学 | 84篇 |
晶体学 | 3篇 |
力学 | 3篇 |
数学 | 107篇 |
物理学 | 112篇 |
出版年
2022年 | 2篇 |
2021年 | 7篇 |
2019年 | 4篇 |
2018年 | 3篇 |
2017年 | 4篇 |
2016年 | 3篇 |
2015年 | 3篇 |
2014年 | 7篇 |
2013年 | 17篇 |
2012年 | 12篇 |
2011年 | 10篇 |
2010年 | 8篇 |
2009年 | 8篇 |
2008年 | 7篇 |
2007年 | 13篇 |
2006年 | 10篇 |
2005年 | 15篇 |
2004年 | 11篇 |
2003年 | 4篇 |
2002年 | 12篇 |
2001年 | 13篇 |
2000年 | 4篇 |
1999年 | 6篇 |
1998年 | 7篇 |
1997年 | 6篇 |
1996年 | 6篇 |
1995年 | 5篇 |
1994年 | 2篇 |
1993年 | 3篇 |
1992年 | 7篇 |
1991年 | 7篇 |
1989年 | 4篇 |
1988年 | 2篇 |
1986年 | 6篇 |
1985年 | 10篇 |
1984年 | 5篇 |
1983年 | 5篇 |
1982年 | 3篇 |
1981年 | 11篇 |
1980年 | 6篇 |
1979年 | 5篇 |
1978年 | 4篇 |
1977年 | 2篇 |
1976年 | 3篇 |
1975年 | 4篇 |
1974年 | 3篇 |
1971年 | 2篇 |
1970年 | 2篇 |
1969年 | 1篇 |
1968年 | 2篇 |
排序方式: 共有309条查询结果,搜索用时 15 毫秒
111.
Photoinduced changes in the optical absorption of large crystals of cadmium sulphide doped with cadmium and copper, are used to store Bragg-angle holograms by means of a He-Ne laser. The recordings are stable in the dark at room temperature and can be erased either optically or thermally. Diffraction efficiencies of over 1% at a write energy of about 1J/cm2 are obtained. 相似文献
112.
General ideas of robust statistics, and specifically robust statistical methods for calibration and dimension reduction are discussed. The emphasis is on analyzing high-dimensional data. The discussed methods are applied using the packages chemometrics and rrcov of the statistical software environment R. It is demonstrated how the functions can be applied to real high-dimensional data from chemometrics, and how the results can be interpreted. 相似文献
113.
O. Mekenyan S. Dimitrov T. Pavlov G. Dimitrova M. Todorov P. Petkov 《SAR and QSAR in environmental research》2013,24(5-6):553-606
Animals and humans are exposed to a wide array of xenobiotics and have developed complex enzymatic mechanisms to detoxify these chemicals. Detoxification pathways involve a number of biotransformations, such as oxidation, reduction, hydrolysis and conjugation reactions. The intermediate substances created during the detoxification process can be extremely toxic compared with the original toxins, hence metabolism should be accounted for when hazard effects of chemicals are assessed. Alternatively, metabolic transformations could detoxify chemicals that are toxic as parents. The aim of the present paper is to describe specificity of eukaryotic metabolism and its simulation and incorporation in models for predicting skin sensitization, mutagenicity, chromosomal aberration, micronuclei formation and estrogen receptor binding affinity implemented in the TIMES software platform. The current progress in model refinement, data used to parameterize models, logic of simulating metabolism, applicability domain and interpretation of predictions are discussed. Examples illustrating the model predictions are also provided. 相似文献
114.
Castellan JP Rosenkranz S Goremychkin EA Chung DY Todorov IS Kanatzidis MG Eremin I Knolle J Chubukov AV Maiti S Norman MR Weber F Claus H Guidi T Bewley RI Osborn R 《Physical review letters》2011,107(17):177003
We report inelastic neutron scattering measurements of the resonant spin excitations in Ba(1-x)K(x)Fe(2)As(2) over a broad range of electron band filling. The fall in the superconducting transition temperature with hole doping coincides with the magnetic excitations splitting into two incommensurate peaks because of the growing mismatch in the hole and electron Fermi surface volumes, as confirmed by a tight-binding model with s(±)-symmetry pairing. The reduction in Fermi surface nesting is accompanied by a collapse of the resonance binding energy and its spectral weight, caused by the weakening of electron-electron correlations. 相似文献
115.
The title compounds were prepared by direct reactions of the corresponding elements at high temperature. They are isostructural with each other (monoclinic, P2(1)/m, Z = 2; Na(8)BaPb(6), a = 13.116(4), b = 5.351(1), and c = 16.166(5) A, beta = 108.07(2) degrees; Na(8)BaSn(6), a = 12.897(4), b = 5.362(1), and c = 16.826(5) A, beta = 108.19(2) degrees; Na(8)EuSn(6), a = 12.912(2), b = 5.220(1), and c = 15.721(2) A, beta = 108.09(1) degrees ) and contain isolated, flat, and aromatic pentagonal rings of Sn(5)(6)(-) and Pb(5)(6)(-) as well as isolated anions of Sn(4)(-) and Pb(4)(-). According to four-probe conductivity measurements, the tin compounds, Na(8)BaSn(6) and Na(8)EuSn(6), are semiconducting with band gaps of 0.11 and 0.09 eV, respectively, and are therefore electronically balanced. Magnetic measurements show that Na(8)BaSn(6) is diamagnetic while Na(8)EuSn(6) is paramagnetic and undergoes two transitions at low temperatures. 相似文献
116.
M. A. Goberna L. Hernández M. I. Todorov 《Journal of Optimization Theory and Applications》2005,124(2):363-386
A linear inequality system with infinitely many constraints is polynomial [analytical] if its index set is a compact interval of the real line and all its coefficients are polynomial [analytical] functions of the index on this interval. This paper provides sufficient conditions for a given closed convex set to be the solution set of a certain polynomial or at least analytical system.The authors are indebted to Dr. J. M. Almira for valuable comments and suggestions. 相似文献
117.
A natural supersymmetric extension
is defined of the current (= affine Kac-Moody Lie) algebra
; it corresponds to a superconformal and chiral invariant 2-dimensional quantum field theory (QFT), and hence appears as an ingredient in superstring models. All unitary irreducible positive energy representations of
are constructed. They extend to unitary representations of the semidirect sumS
(G) of
with the superconformal algebra of Neveu-Schwarz, for
, or of Ramond, for =0.On leave of absence from the Institute for Nuclear Research and Nuclear Energy of the Bulgarian Academy of Sciences, BG-1184 Sofia, Bulgaria 相似文献
118.
Bojko Bakalov Nikolay M. Nikolov Karl-Henning Rehren Ivan Todorov 《Communications in Mathematical Physics》2007,271(1):223-246
The superselection sectors of two classes of scalar bilocal quantum fields in D ≥ 4 dimensions are explicitly determined by working out the constraints imposed by unitarity. The resulting classification
in terms of the dual of the respective gauge groups U(N) and O(N) confirms the expectations based on general results obtained in the framework of local nets in algebraic quantum field theory,
but the approach using standard Lie algebra methods rather than abstract duality theory is complementary. The result indicates
that one does not lose interesting models if one postulates the absence of scalar fields of dimension D−2 in models with global conformal invariance. Another remarkable outcome is the observation that, with an appropriate choice
of the Hamiltonian, a Lie algebra embedded into the associative algebra of observables completely fixes the representation
theory. 相似文献
119.
120.
Makreski Petre Todorov Jovica Jovanovski Gligor Stojanovska Monika Petrushevski Gjorgji 《Journal of Thermal Analysis and Calorimetry》2019,135(4):2265-2276
Journal of Thermal Analysis and Calorimetry - The work represents a pioneering attempt to couple TG analysis and hot-stage t-ATR-FTIR spectroscopy to describe the dehydration and dehydroxylation... 相似文献