全文获取类型
收费全文 | 2325篇 |
免费 | 93篇 |
国内免费 | 7篇 |
专业分类
化学 | 1657篇 |
晶体学 | 25篇 |
力学 | 56篇 |
数学 | 321篇 |
物理学 | 366篇 |
出版年
2022年 | 18篇 |
2021年 | 25篇 |
2020年 | 21篇 |
2019年 | 25篇 |
2018年 | 21篇 |
2017年 | 10篇 |
2016年 | 53篇 |
2015年 | 50篇 |
2014年 | 62篇 |
2013年 | 148篇 |
2012年 | 117篇 |
2011年 | 143篇 |
2010年 | 87篇 |
2009年 | 68篇 |
2008年 | 121篇 |
2007年 | 124篇 |
2006年 | 140篇 |
2005年 | 120篇 |
2004年 | 128篇 |
2003年 | 96篇 |
2002年 | 86篇 |
2001年 | 22篇 |
2000年 | 29篇 |
1999年 | 22篇 |
1998年 | 28篇 |
1997年 | 29篇 |
1996年 | 35篇 |
1995年 | 25篇 |
1994年 | 28篇 |
1993年 | 28篇 |
1992年 | 18篇 |
1991年 | 20篇 |
1990年 | 18篇 |
1989年 | 28篇 |
1988年 | 21篇 |
1987年 | 14篇 |
1986年 | 22篇 |
1985年 | 34篇 |
1984年 | 36篇 |
1983年 | 26篇 |
1982年 | 22篇 |
1981年 | 29篇 |
1980年 | 32篇 |
1979年 | 21篇 |
1978年 | 20篇 |
1977年 | 29篇 |
1976年 | 20篇 |
1975年 | 24篇 |
1974年 | 16篇 |
1973年 | 21篇 |
排序方式: 共有2425条查询结果,搜索用时 15 毫秒
1.
Guy Bayada 《Journal of Mathematical Analysis and Applications》2003,282(1):212-231
The asymptotic behaviour of a Stokes flow with Tresca free boundary friction conditions when one dimension of the fluid domain tends to zero is studied. A specific Reynolds equation associated with variational inequalities is obtained and uniqueness is proved. 相似文献
2.
Guy Schmitz 《国际化学动力学杂志》2007,39(1):17-21
At bromide concentrations higher than 0.1 M, a second term must be added to the classical rate law of the bromate–bromide reaction that becomes ?d[BrO3?]/dt = [BrO3?][H+]2(k1[Br?] + k2[Br?]2). In perchloric solutions at 25°C, k1 = 2.18 dm3 mol?3 s?1 and k2 = 0.65 dm4 mol?4 s?1 at 1 M ionic strength and k1 = 2.60 dm3 mol3 s?1and k2 = 1.05 dm4 mol?4 s?1 at 2 M ionic strength. A mechanism explaining this rate law, with Br2O2 as key intermediate species, is proposed. Errors that may occur when using the Guggenheim method are discussed. © 2006 Wiley Periodicals, Inc. Int J Chem Kinet 39: 17–21, 2007 相似文献
3.
Girard V Farrenq R Sorokin E Sorokina IT Guelachvili G Picqué N 《Chemical physics letters》2006,419(4-6):584-588
The spectral dynamics of a mid-infrared multimode Cr(2+):ZnSe laser located in a vacuum sealed chamber containing acetylene at low pressure is analyzed by a stepping-mode high-resolution time-resolved Fourier transform interferometer. Doppler-limited absorption spectra of C(2)H(2) in natural isotopic abundance are recorded around 4000 cm(-1) with kilometric absorption path lengths and sensitivities better than 3 10(-8) cm(-1). Two cold bands are newly identified and assigned to the ν(1)+ν(4) (1) and ν(3)+ν(5) (1) transitions of (12)C(13)CH(2). The ν(1)+ν(5) (1) band of (12)C(2)HD and fourteen (12)C(2)H(2) bands are observed, among which for the first time ν(2)+2ν(4) (2)+ν(5) (-1). 相似文献
4.
5.
This study provides a stability theory for the nonlinear least-squares formulation of estimating the diffusion coefficient in a two-point boundary-value problem from an error-corrupted observation of the state variable. It is based on analysing the projection of the observation on the nonconvex attainable set.This research was started while G. Chavent visited the Technical University of Graz. Support through the Steiermaerkische Landesregierung is gratefully acknowledged. 相似文献
6.
Serge Palacin Christophe Bureau Julienne Charlier Guy Deniau Brigitte Mouanda Pascal Viel 《Chemphyschem》2004,5(10):1468-1481
Electrografting is a powerful and versatile technique for modifying and decorating conducting surfaces with organic matter. Mainly based on the electro-induced polymerization of dissolved electro-active monomers on metallic or semiconducting surfaces, it finds applications in various fields including biocompatibility, protection against corrosion, lubrication, soldering, functionalization, adhesion, and template chemistry. Starting from experimental observations, this Review highlights the mechanism of the formation of covalent metal-carbon bonds by electro-induced processes, together with major applications such as derivatization of conducting surfaces with biomolecules that can be used in biosensing, lubrication of low-level electrical contacts, reversible trapping of ionic waste on reactive electrografted surfaces as an alternative to ion-exchange resins, and localized modification of conducting surfaces, a one-step process providing submicrometer grafted areas and which is used in microelectronics. 相似文献
7.
A phenanthridinium salt was prepared in four steps, including an intramolecular CH-arylation and a hydride abstraction reaction. Treatment with sterically demanding bases does not lead to the corresponding carbene, but rather to addition products: the planar-constrained geometry significantly enhances the electrophilicity over the acidity of C-aryl iminium salts. 相似文献
8.
In order to determine the energetic driving forces for surface segregation in bimetallic clusters, we use a combined approach coupling numerical simulations within an N-body interatomic potential and a lattice-gas model. This approach, which has been used successfully to study both the superficial segregation in semi-infinite alloys and the intergranular segregation, allows us to determine the relative contributions of the three elementary driving forces for the different sites of the cluster surface (vertices, edges and facets) in both dilute limits for the Cu-Ag system. We show that the segregation hierarchy based on broken-bond arguments (preferential segregation to the vertex sites, less to edge sites, and least to facet sites) is not at all universal. In particular, unusual hierarchies are predicted when the sizes of the constituents are strongly different. Furthermore, we compare the segregation driving forces for cubo-octahedral and icosahedral clusters. They are similar for the vertex sites and edge sites, whereas they differ significantly for the sites of the triangular facets. The segregation of the species with the largest atomic radius (Ag) is indeed largely enhanced in the icosahedral structure due to dilations of the orthoradial distances. 相似文献
9.
10.
Nicolas Meyer Mohamad Nasser Eddine Christelle Delaite Guy Hurtrez Philippe Dumas 《Journal of polymer science. Part A, Polymer chemistry》2003,41(21):3329-3335
The reactions of polystyryllithium and potassium on dimethoxymethyl 1,1‐diphenylethylene derivatives were studied in different solvents. In a polar medium, A3 and A6 star types were formed according to the stoichiometry, whereas in a nonpolar medium, hyperbranched structures were synthesized. Extensions of an already proposed mechanism in polar and nonpolar media were examined. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3329–3335, 2003 相似文献