全文获取类型
收费全文 | 444篇 |
免费 | 12篇 |
国内免费 | 18篇 |
专业分类
化学 | 77篇 |
晶体学 | 7篇 |
力学 | 138篇 |
数学 | 31篇 |
物理学 | 221篇 |
出版年
2023年 | 15篇 |
2022年 | 6篇 |
2021年 | 7篇 |
2020年 | 9篇 |
2019年 | 4篇 |
2018年 | 12篇 |
2017年 | 10篇 |
2016年 | 11篇 |
2015年 | 16篇 |
2014年 | 28篇 |
2013年 | 35篇 |
2012年 | 20篇 |
2011年 | 32篇 |
2010年 | 26篇 |
2009年 | 35篇 |
2008年 | 33篇 |
2007年 | 27篇 |
2006年 | 34篇 |
2005年 | 16篇 |
2004年 | 12篇 |
2003年 | 11篇 |
2002年 | 14篇 |
2001年 | 8篇 |
2000年 | 9篇 |
1999年 | 10篇 |
1998年 | 7篇 |
1997年 | 4篇 |
1996年 | 10篇 |
1995年 | 1篇 |
1994年 | 2篇 |
1993年 | 4篇 |
1991年 | 1篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1986年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
排序方式: 共有474条查询结果,搜索用时 31 毫秒
31.
32.
Structural analysis of proteins using the emission of intrinsic fluorophores is complicated by spectral overlap. Anisotropy resolved multidimensional emission spectroscopy (ARMES) overcame the overlap problem by the use of anisotropy, with chemometric analysis, to better resolve emission from different fluorophores. Total synchronous fluorescence scan (TSFS) provided information about all the fluorophores that contributed to emission while anisotropy provided information about the environment of each fluorophore. Here the utility of ARMES was demonstrated via study of the chemical and thermal denaturation of human serum albumin (HSA). 相似文献
33.
34.
In this contribution, an inverse identification strategy of constitutive laws for elastoplastic behaviour is presented. The proposed inverse algorithm is composed on an appropriate finite element calculation combined with an optimisation procedure. It is applied to identify material anisotropic coefficients using a set up of easy performed laboratory tests. The used experimental data are the plane tensile test and the off axes tensile tests. The identified behaviour models are mainly based on Hill's quadratic yield criterion. Two cases of this yield criterion have been considered: the transverse isotropic and the orthotropic one under an associated and non-associated flow rule assumptions for each case. The yield surface has been assumed to expand isotropically (isotropic strain hardening law) as a function of the plastic work.In order to better describe anisotropic plastic properties of the studied materials, a recently planar anisotropic yield function is used. It is a non-quadratic yield criterion which takes account of anisotropic yield stresses as well as anisotropic strain ratios. It is subsequently shown that the agreement between inverse identification results and experimental measurements were improved.We prove also that the presented strategy is a good alternative to the simplified homogeneous tests assumption, especially for the plane tensile test. 相似文献
35.
Relations Between Relaxation Modulus and Creep Compliance in Anisotropic Linear Viscoelasticity 总被引:2,自引:0,他引:2
The results obtained previously for scalar and class P completely monotone relaxation moduli are extended to arbitrary anisotropy.
It is shown for general anisotropic viscoelastic media that, if the relaxation modulus is a locally integrable completely
monotone function, then the creep compliance is a Bernstein function and conversely. The elastic and equilibrium limits of
the two material functions are related to each other. The relaxation modulus or its derivative can be singular at 0. A rigorous
general formulation of the relaxation spectrum in an anisotropic viscoelastic medium is given. The effect of Newtonian viscosity
on creep compliance is examined.
Put some makeup on him and lay him to rest. Anonymous 相似文献
36.
Magnus Ekh Robert Lillbacka Kenneth Runesson 《International Journal of Plasticity》2004,20(12):2143-2159
We develop a model framework for anisotropic damage coupled to crystal (visco)plasticity, which is based on the concept of a fictitious (undamaged) configuration. The theoretical setting is that of finite strains, which is natural when studying crystal inelasticity even in the case of actual small strains. It turns out that the evolution law for damage, which reflects degradation in the slip planes and which is the key new relation, bears strong resemblance with the inelastic flow rule. Some numerical results showing qualitatively the anisotropic development of damage concludes the paper. 相似文献
37.
Hill's 1948 anisotropic theory of plasticity (Hill, R., 1948. A theory of yielding and plastic flow of anisotropic metals. Proc. Roy. Soc. London A193, 281–297) is extended to include the concept of combined isotropic-kinematic hardening, and the objective of this paper is to validate the model so that it may be useful for analyses of sheet metal forming. Isotropic hardening and kinematic hardening may be experimentally observed in sheet metals, if yielding is defined by the proportional limit or by a small proof strain. In this paper, a single exponential term is used to describe isotropic hardening and Prager's linear kinematic hardening rule is applied for simplicity. It is shown that this model can satisfactorily describe both the yield stress and the plastic strain ratio, the R-ratio, observed in tension test of specimens cut at various angles measured from the rolling direction of the sheet. Kinematic hardening leads to a gradual change in the direction of the plastic strain increment, as the axial strain increases in the tension test; while in the traditional approach for sheet metal, this direction does not change due to the use of isotropic hardening. 相似文献
38.
The rapid, quantitative analysis of the complex cell culture media used in biopharmaceutical manufacturing is of critical importance. Requirements for cell culture media composition profiling, or changes in specific analyte concentrations (e.g. amino acids in the media or product protein in the bioprocess broth) often necessitate the use of complicated analytical methods and extensive sample handling. Rapid spectroscopic methods like multi-dimensional fluorescence (MDF) spectroscopy have been successfully applied for the routine determination of compositional changes in cell culture media and bioprocess broths. Quantifying macromolecules in cell culture media is a specific challenge as there is a need to implement measurements rapidly on the prepared media. However, the use of standard fluorescence spectroscopy is complicated by the emission overlap from many media components. Here, we demonstrate how combining anisotropy measurements with standard total synchronous fluorescence spectroscopy (TSFS) provides a rapid, accurate quantitation method for cell culture media. Anisotropy provides emission resolution between large and small fluorophores while TSFS provides a robust measurement space. Model cell culture media was prepared using yeastolate (2.5 mg mL–1) spiked with bovine serum albumin (0 to 5 mg mL–1). Using this method, protein emission is clearly discriminated from background yeastolate emission, allowing for accurate bovine serum albumin (BSA) quantification over a 0.1 to 4.0 mg mL–1range with a limit of detection (LOD) of 13.8 μg mL–1. 相似文献
39.
The Diels-Alder adduct of phencyclone and N-n-butylmaleimide has been prepared, and NMR studies have been carried out in CDCl3 solution at ambient temperatures by one-and two-dimensional 1H NMR (300 MHz) and 13C NMR (75 MHz) techniques. The resulting spectra appear to be consistent with slow rotation about the hindered C(sp2)-C(sp3) bonds to the bridgehead unsubstituted phenyls, i.e., slow exchange limit (SEL) spectra. Full rigorous 1H spectral assignments have been made via high-resolution COSY experiments. The number of signals in the 13C NMR aryl region were also consistent with hindered phenyl rotations; preliminary 13C assignments are given. Striking evidence for magnetic anisotropic effects due to the phenanthrene moiety, bridging ketone carbonyl, and bridgehead phenyls are discussed, supporting endo stereochemical assignment of the adduct. 相似文献
40.
This paper briefly describes an acoustical transmission traveltime tomography method to simultaneously account for the anisotropy and heterogeneity of media. This method is applied to real data gathered at the rock wall of an underground plant in southwest China. The anisotropic tomograms reveal the rock wall features, which coincide well with the site observations, and provide very useful information for the evaluation and reinforcement of the rock wall. 相似文献