全文获取类型
收费全文 | 1064篇 |
免费 | 49篇 |
国内免费 | 7篇 |
专业分类
化学 | 726篇 |
晶体学 | 1篇 |
力学 | 23篇 |
数学 | 164篇 |
物理学 | 206篇 |
出版年
2023年 | 17篇 |
2022年 | 11篇 |
2021年 | 35篇 |
2020年 | 26篇 |
2019年 | 27篇 |
2018年 | 11篇 |
2017年 | 13篇 |
2016年 | 39篇 |
2015年 | 37篇 |
2014年 | 40篇 |
2013年 | 66篇 |
2012年 | 65篇 |
2011年 | 70篇 |
2010年 | 35篇 |
2009年 | 43篇 |
2008年 | 41篇 |
2007年 | 60篇 |
2006年 | 43篇 |
2005年 | 51篇 |
2004年 | 40篇 |
2003年 | 28篇 |
2002年 | 35篇 |
2001年 | 16篇 |
2000年 | 7篇 |
1999年 | 18篇 |
1998年 | 13篇 |
1997年 | 13篇 |
1996年 | 17篇 |
1995年 | 10篇 |
1994年 | 11篇 |
1993年 | 17篇 |
1992年 | 21篇 |
1991年 | 6篇 |
1990年 | 5篇 |
1987年 | 5篇 |
1986年 | 13篇 |
1985年 | 10篇 |
1984年 | 4篇 |
1983年 | 5篇 |
1982年 | 7篇 |
1980年 | 11篇 |
1979年 | 7篇 |
1978年 | 5篇 |
1977年 | 4篇 |
1976年 | 8篇 |
1975年 | 7篇 |
1974年 | 7篇 |
1973年 | 3篇 |
1972年 | 6篇 |
1971年 | 4篇 |
排序方式: 共有1120条查询结果,搜索用时 453 毫秒
1.
Cavitation erosion is caused in solids exposed to strong pressure waves developing in an adjacent fluid field. The knowledge of the transient distribution of stresses in the solid is important to understand the cause of damaging by comparisons with breaking points of the material. The modeling of this problem requires the coupling of the models for the fluid and the solid. For this purpose, we use a strategy based on the solution of coupled Riemann problems that has been originally developed for the coupling of 2 fluids. This concept is exemplified for the coupling of a linear elastic structure with an ideal gas. The coupling procedure relies on the solution of a nonlinear equation. Existence and uniqueness of the solution is proven. The coupling conditions are validated by means of quasi‐1D problems for which an explicit solution can be determined. For a more realistic scenario, a 2D application is considered where in a compressible single fluid, a hot gas bubble at low pressure collapses in a cold gas at high pressure near an adjacent structure. 相似文献
2.
3.
High-precision sub-pixel interpolation in particle image velocimetry image processing 总被引:4,自引:0,他引:4
The task of image interpolation and re-sampling for particle image velocimetry (PIV) is investigated, which is used for window shifting with sub-pixel accuracy and image or window deformation. A new interpolation scheme based on a Gaussian filter is introduced and compared with commonly used and widely accepted interpolation techniques in terms of the achievable root mean square deviation of the displacement estimates. 相似文献
4.
5.
Screening of 400 Streptomyces strains for biotransformation of the natural lignan matairesinol led to the identification of Streptomyces sp. LS136, capable of producing a single metabolite in moderate yields. Isolation and purification by preparative HPLC, followed by structural analyses by LC-MS and NMR, established the structure as matairesinol-4-O-rhamnoside. This bacterial strain was also used for rhamnosylation of the abundant natural lignans, hydroxymatairesinol and secoisolariciresinol. 相似文献
6.
7.
An immobiline DryStrip application method enabling high-capacity two-dimensional gel electrophoresis 总被引:5,自引:0,他引:5
Sabounchi-Schütt F Aström J Olsson I Eklund A Grunewald J Bjellqvist B 《Electrophoresis》2000,21(17):3649-3656
In the field of proteomics the need to detect low-abundance cellular components, such as regulatory proteins, is of critical importance. Two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) is one of the most commonly used separation tools for these biological investigations. In this paper we report an alternative micropreparative 2-D PAGE sample application method, called the "paper bridge loading" method. This method makes it possible to apply a larger sample volume to commercially available immobilized pH gradient (IPG) strips. The Vh products required for focusing are only marginally longer than those used in analytical experiments. The method was compared to traditional cup loading and in-gel rehydration. With 18 cm long narrow-range Immobiline DryStrip pH 4.5-5.5, the "paper bridge" method allowed the application of 10 mg human plasma proteins compared to 3 mg with traditional loading methods. The corresponding figures using Escherichia coli sample was found to be 6 mg and less than 2 mg, respectively. The paper bridge method also showed the best results in terms of spot resolution and separation of high molecular weight proteins. 相似文献
8.
9.
Nils G. A. Ekelund Christer Sundqvist Peter H. Quail Richard D. Vierstra 《Photochemistry and photobiology》1985,41(2):221-223
Abstract— From light-induced changes in linear dichroism, we have calculated the rotation of the long-wavelength-absorbing transition moment that occurs during phototransformation of 124-kilodalton Avena sativa phytochrome. Phytochrome was purified to homogeneity and immobilized onto Sepharose beads covalently coated with antibodies against A. sativa phytochrome. Changes in linear dichroism were induced by plane-polarized red or far-red light and measured by the absorbance differences at 660 and 730 nm using a dual-wavelength spectrophotometer equipped with polarizing filters in the measuring beams. From such measurements, we calculate a rotation angle of 31o (or 149o ) during photoconversion of Pr to Pfr and 30o (or 150o ) during photoconversion of Pfr to Pr. These values are similar to the value of 32o (or 148o ) reported earlier for the rotation of the transition moment of "large" A. sativa phytochrome (∽ 120 kilodalton) isolated under conditions that did not preclude post homogenization proteolysis of the 124 kilodalton molecule. 相似文献
10.
The 4p photoelectron spectra of metallic Nb, Mo, Ru and Rh have been recorded. By use of a deconvolution procedure it is shown that the 4p spin-orbit component has a linewidth which significantly exceeds that of the 4p component. This suggests that N2N3N45 super Coster Kronig processes give a considerable contribution to the decay rata of the 4p hole state. 相似文献