全文获取类型
收费全文 | 2118篇 |
免费 | 75篇 |
国内免费 | 18篇 |
专业分类
化学 | 1408篇 |
晶体学 | 6篇 |
力学 | 75篇 |
数学 | 438篇 |
物理学 | 284篇 |
出版年
2022年 | 18篇 |
2021年 | 17篇 |
2020年 | 19篇 |
2019年 | 35篇 |
2018年 | 28篇 |
2017年 | 20篇 |
2016年 | 49篇 |
2015年 | 61篇 |
2014年 | 47篇 |
2013年 | 142篇 |
2012年 | 120篇 |
2011年 | 124篇 |
2010年 | 91篇 |
2009年 | 74篇 |
2008年 | 123篇 |
2007年 | 123篇 |
2006年 | 110篇 |
2005年 | 98篇 |
2004年 | 120篇 |
2003年 | 95篇 |
2002年 | 93篇 |
2001年 | 39篇 |
2000年 | 37篇 |
1999年 | 25篇 |
1998年 | 27篇 |
1997年 | 21篇 |
1996年 | 43篇 |
1995年 | 23篇 |
1994年 | 25篇 |
1993年 | 14篇 |
1992年 | 26篇 |
1991年 | 15篇 |
1990年 | 7篇 |
1989年 | 23篇 |
1988年 | 16篇 |
1987年 | 8篇 |
1986年 | 13篇 |
1985年 | 20篇 |
1984年 | 18篇 |
1983年 | 15篇 |
1982年 | 21篇 |
1981年 | 21篇 |
1980年 | 20篇 |
1979年 | 14篇 |
1978年 | 15篇 |
1977年 | 19篇 |
1976年 | 12篇 |
1975年 | 12篇 |
1974年 | 15篇 |
1973年 | 19篇 |
排序方式: 共有2211条查询结果,搜索用时 15 毫秒
11.
Molinier V Fenet B Fitremann J Bouchu A Queneau Y 《Journal of colloid and interface science》2005,286(1):360-368
The micellization of pure monosubstituted sucrose fatty acid esters in water, namely sucrose octanoate, sucrose decanoate, sucrose laurate, sucrose dodec-5-cis-enoate, sucrose myristate, and sucrose palmitate, has been investigated by means of two NMR methods, pulsed field gradient spin-echo NMR (PFGSE-NMR), giving access to the self-diffusion coefficients of free molecules and micelles in solution, and the ERETIC method (electronic reference to access in vivo concentrations) for the measurement of concentrations by external calibration of a synthetic NMR signal. The early micellar regions and, when possible, the premicellar regions were investigated. By this method, we obtained the hydrodynamic radii of micelles, displaying a linear progression in relation to the chain length and an accurate determination of critical micellar concentration (CMC) for each sucrose ester. The effect of the regiochemistry of fatty chain grafting has been investigated, showing special behavior for 1'-O-sucrose palmitate. 相似文献
12.
Yves Martin 《Transactions of the American Mathematical Society》1996,348(12):4825-4856
Let be the Dedekind -function. In this work we exhibit all modular forms of integral weight , for positive integers and and arbitrary integers , such that both and its image under the Fricke involution are eigenforms of all Hecke operators. We also relate most of these modular forms with the Conway group via a generalized McKay-Thompson series.
13.
14.
Improved L.C.A.O. method primitively built for conjugated molecules holding only atoms of second row in the periodic classification is extended to molecules holding atoms of the third row. The application is done for thiophen, thioketones, SO2 and SO3. d orbitals are not introduced in this study. Discussion about results shows that d orbitals must be introduced when the sulphur atom is strongly positively charged like in sulphur oxides. 相似文献
15.
Francois Delyon Yves Lévy Bernard Souillard 《Communications in Mathematical Physics》1985,100(4):463-470
We prove that discrete Schrödinger operators on
d
with a random-potential have almost-surely only pure point spectrum and exponentially decaying eigenfunctions for large disorder or large energy. This is the first proof of localization for multi-dimensional Anderson models.Groupe de recherche 048 du CNRS 相似文献
16.
We investigate a piecewise linear (area-preserving) mapT describing two coupled baker transformations on two squares, with coupling parameter 0c1. The resulting dynamical system is Kolmogorov for anyc0. For rational values ofc, we construct a generating partition on whichT induces a Markov chain. This Markov structure is used to discuss the decay of correlation functions: exponential decay is found for a class of functions related to the partition. Explicit results are given forc=2–n. The macroscopic analog of our model is a leaking process between two (badly) stirred containers: according to the Markov analysis, the corresponding progress variable decays exponentially, but the rate coefficients characterizing this decay are not those determined from the one-way flux across the cell boundary. The validity of the macroscopic rate law is discussed. 相似文献
17.
Trimethylsilyl bromide is an effective reagent for the deprotection of methoxymethyl ethers under mild conditions. 相似文献
18.
The reactivity of (diethoxy)-N-methyl-N-benzyl phosphoramide (I) and bis(dinethylamino)-N-methyl-N-benzylphosphoramide (II) when treated with strong bases (RLi, R2NLi) is very different: (I) gives a novel elimination, whereas (II) under the same experimental conditions gives a stable carbanion whose reactivity has been investigated. 相似文献
19.
Yves Biollay 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》1980,31(5):556-567
Summary We consider here the Dirichlet's problem for the Lamé's equations without body force in a semi-infinite cylinder (0z<) with cross-sectionS
z
, the displacementsu
i
vanishing on the cylindrical surface. We give in this paper an explicit decay estimate for aL
2-norm ofu
i
. The evaluation is of the type
wherek
1 andk
2 are determined constants andI(f
i
) an integral depending only on the displacementsf
i
prescribed onS
0. Our results consequently reinforce the Saint-Venant's principle.
Résumé On considère ici le problème de Dirichlet pour les équations de Lamé sans force volumique dans un cylindre semi-infini (0z<) de section droiteS z , les déplacementsu i étant nuls sur la surface cylindrique. On donne dans ce travail une estimation explicite de la décroissance pour une norme (dansL 2) desu i . L'évaluation est du type oùk 1 etk 2 sont des constantes déterminées etI(f i ) une intégrale ne dépendant que des déplacementsf i imposés surS 0. Notre résultat, par conséquent, renforce le principe de Saint-Venant.相似文献
20.
Anne Astier Jean-Claude Daran Yves Jeannin Catherine Rigault 《Journal of organometallic chemistry》1983,241(1):53-68
Syntheses and single-crystal X-ray diffraction studies have been completed on two cycloruthenapentadienyl (CO)6Ru2L2 derivatives, with L = CH2OHC = CCH2OH and C2H5C=CCH2CH2OH respectively. Crystal data are as follows: for [(CO)3RuC4(CH2OH)4]Ru(CO)3·H2O, P21/c, a 13.72(1), b 9.501(4), c 14.86(1) Å, β 101.10(6)°, Rw = 0.052 for 1911 reflections; for [(CO)3RuC4(CH2CH2OH)2(C2H5)2]Ru(CO)3, P21/c, a 9.191(3), b 16.732(4), c 14.903(3) Å, β 113.61(4)°, Rw = 0.042 for 2865 reflections. Both compounds are built up from binuclear units, each unit being regarded as a Ru(CO)3 fragment π-bonded to a cycloruthenapentadienyl ring. The molecular parameters are compared with those of known cyclometallapentadienyl complexes of transition metals. The presence of a semi-bridging CO group is discussed. 相似文献