全文获取类型
收费全文 | 2719篇 |
免费 | 99篇 |
国内免费 | 5篇 |
专业分类
化学 | 2239篇 |
晶体学 | 15篇 |
力学 | 22篇 |
数学 | 272篇 |
物理学 | 275篇 |
出版年
2024年 | 2篇 |
2023年 | 21篇 |
2022年 | 74篇 |
2021年 | 83篇 |
2020年 | 65篇 |
2019年 | 57篇 |
2018年 | 28篇 |
2017年 | 37篇 |
2016年 | 84篇 |
2015年 | 92篇 |
2014年 | 94篇 |
2013年 | 169篇 |
2012年 | 182篇 |
2011年 | 214篇 |
2010年 | 125篇 |
2009年 | 119篇 |
2008年 | 207篇 |
2007年 | 210篇 |
2006年 | 172篇 |
2005年 | 165篇 |
2004年 | 113篇 |
2003年 | 109篇 |
2002年 | 72篇 |
2001年 | 29篇 |
2000年 | 44篇 |
1999年 | 21篇 |
1998年 | 18篇 |
1997年 | 19篇 |
1996年 | 16篇 |
1995年 | 17篇 |
1994年 | 12篇 |
1993年 | 16篇 |
1992年 | 11篇 |
1991年 | 7篇 |
1990年 | 11篇 |
1989年 | 3篇 |
1988年 | 7篇 |
1987年 | 10篇 |
1986年 | 10篇 |
1985年 | 16篇 |
1984年 | 11篇 |
1983年 | 6篇 |
1982年 | 6篇 |
1981年 | 8篇 |
1980年 | 7篇 |
1979年 | 8篇 |
1978年 | 6篇 |
1975年 | 2篇 |
1933年 | 1篇 |
1931年 | 1篇 |
排序方式: 共有2823条查询结果,搜索用时 31 毫秒
1.
2.
3.
Marco Biroli Silvia Mataloni Michele Matzeu 《NoDEA : Nonlinear Differential Equations and Applications》2005,12(3):295-321
Some stability results for Mountain Pass and Linking type solutions of semilinear problems involving a very general class
of Dirichlet forms are stated. The non linear terms are supposed to have a suitable superlinear growth and the family of Dirichlet
forms is required to be dominated from below and from above by a fixed diffusion type form. Some concrete examples are also
given. 相似文献
4.
5.
Rodrigo París José Luis de la Fuente 《Journal of polymer science. Part A, Polymer chemistry》2007,45(16):3538-3549
Different diblock copolymers constituted by one segment of a monomer supporting a reactive functional group, like allyl methacrylate (AMA), were synthesized by atom transfer radical polymerization (ATRP). Bromo‐terminated polymers, like polystyrene (PS), poly(methyl methacrylate) (PMMA), and poly(butyl acrylate) (PBA) were employed as macroinitiators to form the other blocks. Copolymerizations were carried out using copper chloride with N,N,N′,N″,N″‐pentamethyldiethylenetriamine (PMDETA) as the catalyst system in benzonitrile solution at 70 °C. At the early stage, the ATRP copolymerizations yielded well‐defined linear block copolymers. However, with the polymerization progress a change in the macromolecular architecture takes place due to the secondary reactions caused by the allylic groups, passing to a branched and/or star‐shaped structure until finally yielding gel at monomer conversion around 40% or higher. The block copolymers were characterized by means of size exclusion chromatography (SEC), 1H NMR spectroscopy, and differential scanning calorimetry (DSC). In addition, one of these copolymers, specifically P(BA‐b‐AMA), was satisfactorily modified through osmylation reaction to obtain the subsequent amphiphilic diblock copolymer of P(BA‐b‐DHPMA), where DHPMA is 2,3‐dihydroxypropyl methacrylate; demonstrating the feasibility of side‐chain modification of the functional obtained copolymers. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3538–3549, 2007 相似文献
6.
Silvia Vogel 《Annals of Operations Research》2006,142(1):269-282
The paper considers upper semicontinuous behavior in distribution of sequences of random closed sets. Semiconvergence in distribution
will be described via convergence in distribution of random variables with values in a suitable topological space. Convergence
statements for suitable functions of random sets are proved and the results are employed to derive stability statements for
random optimization problems where the objective function and the constraint set are approximated simultaneously.
The author is grateful to two anonymous referees for helpful suggestions. 相似文献
7.
In [7] point-reflection geometries were studied which can be derived from commutative kinematic
spaces without involutory elements. But the class of point-reflection geometries is larger. For example, elliptic
planes with their reflections cannot be derived from commutative kinematic spaces. Here we investigate a larger
class of reflection geometries.This paper was sponsored by Vigoni Program 1999. 相似文献
8.
Silvia Lorenzo-Freire José M. Alonso-Meijide Balbina Casas-Méndez Ruud Hendrickx 《European Journal of Operational Research》2007
Calleja et al. [Calleja, P., Borm, P., Hendrickx, R., 2005. Multi-issue allocation situations. European Journal of Operational Research 164, 730–747] introduced multi-issue allocation situations with awards. In this paper, we extend the classical model of cooperative games with transferable utility to the cooperative games with transferable utility and awards. We define a run-to-the-bank rule for cooperative games with transferable utility and awards and characterise it in terms of a property of balanced contributions. We apply our main result to bankruptcy problems and multi-issue allocation situations with awards. 相似文献
9.
In this paper we report the results of a morphological and structural investigation on film properties of a soluble polydiacetylene, the poly[1,6-bis(3,6-dihexadecyl-N-carbazolyl)-2,4-hexadiyne] (polyDCHD-HS). The red films of this polymer, prepared by standard spin-coating techniques, revealed absence of linear dichroism and birefringence in contrast with the ordered mesophases detected by powder X-ray studies. In order to interpret the optical behavior of this polymer, we performed AFM and SEM studies of polyDCHD-HS films spun on hydrophylic and hydrophobic glass substrates. We found the presence of surfaces organized in rod-like particles, more regularly oriented on the hydrophylic substrate. GIXRD studies, carried out on films sufficiently thick to allow the observation of the diffraction pattern, reveled the presence of a lamellar structure with a spacing of 3.22 nm. The low intensity of the diffraction peaks and the isotropic linear optical properties of the films show that the lamellar mesophases are not extended over large areas. These findings were compared with the data obtained from AFM and SEM studies on films of two other polydiacetylenes, the poly[1-(3,6-dihexadexyl-N-carbazolyl)-6-(N-carbazolyl)-2,4-hexadyine] (polya-DCHD) and the poly[1,6-bis(3,6-dipalmitoyl-N-carbazolyl)-2,4-hexadyine] (polyDPCHD), spun on hydrophylic glass substrate. The results confirmed the presence of nodular morphologies which seem to be a general characteristic of this class of materials. The particles organization appears instead related to the chemical nature of the substituents on the carbazolyl rings. 相似文献
10.
Alejandro Balbs Raquel Balbs Silvia Mayoral 《Mathematical and Computer Modelling》2007,45(11-12):1308-1318
The first Fundamental Theorem of Asset Pricing establishes the equivalence between the absence of arbitrage in financial markets and the existence of Equivalent Martingale Measures, if appropriate conditions hold. Since the theorem may fail when dealing with infinitely many trading dates, this paper draws on the A.A. Lyapunov Theorem in order to retrieve the equivalence for complete markets such that the Sharpe Ratio is adequately bounded. 相似文献