全文获取类型
收费全文 | 4146篇 |
免费 | 78篇 |
国内免费 | 22篇 |
专业分类
化学 | 2705篇 |
晶体学 | 25篇 |
力学 | 161篇 |
数学 | 651篇 |
物理学 | 704篇 |
出版年
2021年 | 27篇 |
2020年 | 31篇 |
2019年 | 33篇 |
2018年 | 39篇 |
2017年 | 38篇 |
2016年 | 61篇 |
2015年 | 74篇 |
2014年 | 86篇 |
2013年 | 229篇 |
2012年 | 170篇 |
2011年 | 199篇 |
2010年 | 124篇 |
2009年 | 116篇 |
2008年 | 171篇 |
2007年 | 165篇 |
2006年 | 177篇 |
2005年 | 196篇 |
2004年 | 158篇 |
2003年 | 145篇 |
2002年 | 157篇 |
2001年 | 61篇 |
2000年 | 70篇 |
1999年 | 65篇 |
1998年 | 47篇 |
1997年 | 73篇 |
1996年 | 75篇 |
1995年 | 65篇 |
1994年 | 55篇 |
1993年 | 59篇 |
1992年 | 50篇 |
1991年 | 54篇 |
1990年 | 39篇 |
1989年 | 44篇 |
1988年 | 35篇 |
1987年 | 32篇 |
1985年 | 79篇 |
1984年 | 62篇 |
1983年 | 50篇 |
1982年 | 65篇 |
1981年 | 72篇 |
1980年 | 53篇 |
1979年 | 66篇 |
1978年 | 68篇 |
1977年 | 78篇 |
1976年 | 52篇 |
1975年 | 53篇 |
1974年 | 50篇 |
1973年 | 38篇 |
1971年 | 36篇 |
1968年 | 27篇 |
排序方式: 共有4246条查询结果,搜索用时 15 毫秒
41.
Bernard Helffer 《Letters in Mathematical Physics》1996,38(3):297-312
This Letter gives detailed proofs concerning the analysis of the pair correlations for a nonconvex model. Using the transfer matrix approach, the problem is reduced to the analysis of the spectral properties of this transfer operator. Although the problem is similar to the semiclassical study of the Kac operator presented in a paper with M. Brunaud, which was devoted to the study of exp-(v/2) exp h
2 exp-(v/2) for h small, new features appear for the model exp-(v/2h) exp h exp-(v/2h). Our principal results concern the splitting of this operator between the two largest eigenvalues. We give an upper and a lower bound for this splitting in the semi-classical regime. As a corollary, we get good control of the decay of the pair correlation. Some of the results were announced in a previous paper. Related WKB constructions will be developed in a later paper.Inspired by papers by M. Kac [15, 16]. 相似文献
42.
43.
44.
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
45.
1,3,5-Trisubstituted hexahy drotriazines react with hydrogen chloride in the presence of anhydrous solvents to form useful intermediates for the introduction of the RNHCH2- group into compounds which undergo the Mannich reaction. The effectiveness of the new aminomethyl-ating agent has been demonstrated by the preparation of secondary aminomethyl sulfide hydro-chlorides. 相似文献
46.
Inverse gas chromatography using water probing at 110°C was carried out to characterize rayon yarns after prior heating at 200 and 250°C in both inert (nitrogen) and oxidative (dry air) atmospheres for successively longer time intervals. During the early stages of heating in either atmosphere, the affinity of the rayon for water drops rapidly. However, whereas continued heating in N2 results in a further loss of activity, data have been obtained showing that after an initial period yarns heated in air at 250°C exhibit an increasing attraction for water even while losing more weight. 相似文献
47.
Ibra Gueye Dioum Jacques Vedel Bernard Tremillon 《Journal of Electroanalytical Chemistry》1982,137(2):219-226
Molten potassium tetrachlorogallate and potassium tetraiodogallate were studied in terms of halogenoacidity, based on X? ion-exchange. Titration of KX solution with GaX3 were achieved and characterized by the shift of cathodic voltammetric curves. Autodissociation constants Ki,X/mol2 kg?1 were determined: ?log Ki,Cl=4.25±0.05 and ?log Ki,I=2.6±0.05, as well as the solubility values of KX: 0.41±0.02 and 0.80±0.02 mol kg?1 for KCl and KI respectively. 相似文献
48.
The electrochemically induced dissolution of ferrocene in a carbon paste electrode is investigated by using chronoamperometry at constant potential. Two types of behaviour are observed, according to the initial form of ferrocene: particles or deposit. The experimental i-t curves are respectively in agreement with the theoretical curves, derived earlier, in the case of spherical particles or planar slabs of solid. The analysis of the curve shows that the process is diffusion controlled, so that the dissolution rate of ferrocene cannot be measured. The parameters calculated from the curves (thickness of the deposit, initial distance from the electrode, area) have a reasonable order of magnitude. 相似文献
49.
Summary Using X-ray diffraction techniques, we have determined the specific surface of polar groups in the two structures observed for binary soap-water systems in the mesomorphic state: the cylindrical structure and the lamellar one.This parameter depends upon the temperature, the nature of the polar group, the type of structure of the system and the quantity of water present in the mixture. It is, on the contrary, independent of the length of the paraffin chain of the soap. This result suggests that the role of the electrical state of the aqueous regions is by far the most important.
Zusammenfassung Mit Hilfe der Röntgenstrahlen-Diffraktion wurde die spezifische Fläche polarer Gruppen der zwei wichtigsten Strukturen der binären Seifen/Wasser-Systeme im mesomorphen Zustand bestimmt: die zylindrische und die lamellare Struktur.Diese Größe ist von der Temperatur, der Natur der polaren Gruppen, der Struktur des Systems und des Wassergehaltes der Mischung abhängig. Die spezifische Fläche ist jedoch von der Länge der Seifen-Paraffin-Kette unabhängig. Der elektrische Zustand des wässerigen Teiles scheint also sehr wichtig zu sein.相似文献
50.
Broussy S Bernardes-Génisson V Gornitzka H Bernadou J Meunier B 《Organic & biomolecular chemistry》2005,3(4):666-669
An ortho-metallation-electrophilic substitution sequence was employed as a key step to build the 4-benzoylpyridine framework. It was found that 4-benzoylpyridine-3-carboxamide and an N-pyridyl alkylated derivative both exist in a unique cyclized hemiamidal structure, not in the usually expected keto-amide open form. These structures represent fragment models of the Isoniazid-NAD adducts involved in the mechanism of action of the antituberculous drug Isoniazid. 相似文献