全文获取类型
收费全文 | 2383篇 |
免费 | 104篇 |
国内免费 | 9篇 |
专业分类
化学 | 1542篇 |
晶体学 | 12篇 |
力学 | 87篇 |
数学 | 350篇 |
物理学 | 505篇 |
出版年
2023年 | 19篇 |
2022年 | 22篇 |
2021年 | 51篇 |
2020年 | 62篇 |
2019年 | 75篇 |
2018年 | 59篇 |
2017年 | 42篇 |
2016年 | 106篇 |
2015年 | 72篇 |
2014年 | 84篇 |
2013年 | 151篇 |
2012年 | 163篇 |
2011年 | 170篇 |
2010年 | 103篇 |
2009年 | 89篇 |
2008年 | 150篇 |
2007年 | 134篇 |
2006年 | 107篇 |
2005年 | 111篇 |
2004年 | 101篇 |
2003年 | 74篇 |
2002年 | 90篇 |
2001年 | 32篇 |
2000年 | 33篇 |
1999年 | 21篇 |
1998年 | 28篇 |
1997年 | 25篇 |
1996年 | 18篇 |
1995年 | 14篇 |
1994年 | 9篇 |
1993年 | 13篇 |
1992年 | 12篇 |
1991年 | 16篇 |
1990年 | 11篇 |
1989年 | 13篇 |
1988年 | 7篇 |
1986年 | 7篇 |
1985年 | 11篇 |
1984年 | 17篇 |
1982年 | 12篇 |
1981年 | 12篇 |
1980年 | 14篇 |
1979年 | 14篇 |
1978年 | 20篇 |
1977年 | 8篇 |
1976年 | 8篇 |
1974年 | 9篇 |
1973年 | 11篇 |
1970年 | 7篇 |
1968年 | 10篇 |
排序方式: 共有2496条查询结果,搜索用时 46 毫秒
981.
Résumé. Nous majorons le degré d'une isogénie minimale entre deux modules de Drinfel'd. Il s'agit d'un analogue d'un résultat démontré
tout d'abord sur les courbes elliptiques, puis généralisé aux variétés abéliennes par Masser et Wüstholz. Comme dans le cas
abélien, la majoration dépend uniquement de la hauteur de l'un des modules et du degré d'un corps de définition commun aux
deux modules. Cette dépendance est polyn?miale.
We give a bound for the degree of a minimal isogeny between two Drinfel'd modules. This result is an anlogue of a theorem first proved on elliptic curves and then extended to abelian varieties by Masser and Wüstholz. This upper bound, as in the abelian case depends only on the height of one of the modules and on the degree of a field over which both modules are defined. We get a polynomial bound.
Received: 4 October 1994 / in final form: 30 July 1998 相似文献
982.
Corrado Lattanzio Denis Serre 《NoDEA : Nonlinear Differential Equations and Applications》1999,6(3):319-340
We consider the interaction between shock waves in a semilinear relaxation approximation to N×N systems of conservation laws. This interaction is described by proving the existence of a particular solution to the relaxing
system, with a certain asymptotic as
Received July 1998 相似文献
983.
Philip Kraft JerzyA. Bajgrowicz Caroline Denis Georg Frter 《Angewandte Chemie (International ed. in English)》2000,39(17):2980-3010
Fragrance chemistry is, together with the closely related area of flavor chemistry, one of the few domains, if not the only one, in which chemists can immediately experience structure–activity relationships. This review presents structure–odor correlations and olfactophore models for the main odor notes of perfumery: “fruity”, “marine”, “green”, “floral”, “spicy”, “woody”, “amber”, and “musky”. New trendsetters and so‐called captive odorants of these notes are introduced, and recent activities and highlights in fragrance chemistry are summarized. The design of odorants, their chemical synthesis, and their use in modern perfumery is discussed. Our selection is guided and illustrated by creative fragrances, and features new odorants which encompassed current trends in perfumery. New odorants for grapefruit and blackcurrant, for galbanum, and leafy top notes are presented. Compounds with fashionable marine, ozonic, and aquatic facets are treated, as well as new odorants for classical lily‐of‐the‐valley, rose, and jasmine accords. Compounds with sweet and spicy tonalities are also discussed, as are the most recent developments for woody notes such as sandalwood and vetiver. We conclude with musky and ambery odorants possessing uncommon or unusual structural features. Some odor trends and effects are illustrated by microencapsulated fragrance samples, and areas where there is need for the development of new synthetic materials and methodologies are pointed out. Thus, chemists are invited to explore fragrance chemistry and participate in the design and synthesis of new odorants. This review gives the latest state of the art of the subject. 相似文献
984.
Technical Physics - Single-crystal Bi4Ti3O12 films deposited on a 4-nm-thick Ba0.4Sr0.6TiO3 sublayer covering an MgO(001) substrate have been investigated. It has been found that the unit cells of... 相似文献
985.
Alomar Antoni Nicole Aurlie Sipp Denis Rialland Valrie Vuillot Franois 《Theoretical and Computational Fluid Dynamics》2020,34(1):49-77
Theoretical and Computational Fluid Dynamics - The present article deals with the spatiotemporal reduction of a reacting, supersonic, turbulent jet. A flowfield dataset is first obtained from a LES... 相似文献
986.
987.
Mechanical, calorimetric, dynamic mechanical and dielectric properties were measured in starch and amylose films plasticized by different glycerol contents. Low-temperature relaxation was found to be highly dependent on plasticizer level and related to unusual mechanical properties. 相似文献
988.
Evgeny Filatov Pavel Smirnov Dmitry Potemkin Denis Pishchur Natalya Kryuchkova Pavel Plyusnin Sergey Korenev 《Molecules (Basel, Switzerland)》2022,27(4)
The thermal behaviour of Ag2[PtCl4] and Ag2[PtCl6] complex salts in inert and reducing atmospheres has been studied. The thermolysis of compounds in a helium atmosphere is shown to occur in two stages. At the first stage, the complexes decompose in the temperature range of 350–500 °C with the formation of platinum and silver chloride and the release of chlorine gas. At the second stage, silver chloride is sublimated in the temperature range of 700–900 °C, while metallic platinum remains in the solid phase. In contrast to the thermolysis of Ag2[PtCl6], the thermal decomposition of Ag2[PtCl4] at 350 °C is accompanied by significant heat release, which is associated with disproportionation of the initial salt to Ag2[PtCl6], silver chloride, and platinum metal. It is confirmed by DSC measurements, DFT calculations of a suggested reaction, and XRD. The thermolysis of Ag2[PtCl4] and Ag2[PtCl6] compounds is shown to occur in a hydrogen atmosphere in two poorly separable steps. The compounds are decomposed within 170–350 °C, and silver and platinum are reduced to a metallic state, while a metastable single-phase solid solution of Ag0.67Pt0.33 is formed. The catalytic activity of the resulting nanoalloy Ag0.67Pt0.33 is studied in the reaction of CO total (TOX) and preferential (PROX) oxidation. Ag0.67Pt0.33 enhanced Pt nano-powder activity in CO TOX, but was not selective in CO PROX. 相似文献
989.
990.
Masoud Farhadi‐Khouzani Daniel M. Chevrier Prof. Dr. Peng Zhang Prof. Dr. Niklas Hedin Dr. Denis Gebauer 《Angewandte Chemie (International ed. in English)》2016,55(28):8117-8120
Temperature and pH value can affect the short‐range order of proto‐structured and additive‐free amorphous calcium carbonates (ACCs). Whereas a distinct change occurs in proto‐vaterite (pv) ACC above 45 °C at pH 9.80, proto‐calcite (pc) ACC (pH 8.75) is unaffected within the investigated range of temperatures (7–65 °C). IR and NMR spectroscopic studies together with EXAFS analysis showed that the temperature‐induced change is related to the formation of proto‐aragonite (pa) ACC. The data strongly suggest that the binding of water molecules induces dipole moments across the carbonate ions in pa‐ACC as in aragonite, where the dipole moments are due to the symmetry of the crystal structure. Altogether, a (pseudo‐)phase diagram of the CaCO3 polyamorphism in which water plays a key role can be formulated based on variables of state, such as the temperature, and solution parameters, such as the pH value. 相似文献