全文获取类型
收费全文 | 486篇 |
免费 | 8篇 |
国内免费 | 3篇 |
专业分类
化学 | 199篇 |
晶体学 | 5篇 |
力学 | 16篇 |
数学 | 63篇 |
物理学 | 214篇 |
出版年
2022年 | 5篇 |
2021年 | 10篇 |
2020年 | 4篇 |
2019年 | 12篇 |
2018年 | 8篇 |
2017年 | 14篇 |
2016年 | 21篇 |
2015年 | 10篇 |
2014年 | 12篇 |
2013年 | 18篇 |
2012年 | 24篇 |
2011年 | 23篇 |
2010年 | 16篇 |
2009年 | 13篇 |
2008年 | 24篇 |
2007年 | 15篇 |
2006年 | 12篇 |
2005年 | 11篇 |
2004年 | 9篇 |
2003年 | 10篇 |
2002年 | 9篇 |
2001年 | 11篇 |
2000年 | 8篇 |
1997年 | 6篇 |
1996年 | 4篇 |
1994年 | 4篇 |
1993年 | 8篇 |
1991年 | 5篇 |
1990年 | 6篇 |
1989年 | 4篇 |
1988年 | 4篇 |
1987年 | 4篇 |
1986年 | 9篇 |
1985年 | 7篇 |
1984年 | 15篇 |
1983年 | 5篇 |
1982年 | 7篇 |
1981年 | 8篇 |
1980年 | 10篇 |
1979年 | 4篇 |
1978年 | 6篇 |
1977年 | 8篇 |
1976年 | 7篇 |
1975年 | 11篇 |
1974年 | 6篇 |
1973年 | 5篇 |
1970年 | 6篇 |
1969年 | 3篇 |
1966年 | 6篇 |
1959年 | 3篇 |
排序方式: 共有497条查询结果,搜索用时 46 毫秒
11.
Direct detection of thioester intermediate mixtures bound to EpoC, a 195 kDa polyketide synthase, has been achieved using limited proteolysis and Fourier-transform mass spectrometry (FTMS). Incubation with various N-acetylcysteamine thioester (S-NAC) substrate mimics produced mass shifts on the EpoC ACP domain consistent with their condensation with an enzyme-bound carbanion produced by the decarboxylation of methylmalonyl-S-EpoC. Reconstitution of EpoA-ACP, EpoB, and EpoC gave a +165.0 Da mass shift consistent with the formation of the methylthiazolyl-methacrylyl product by incorporation of acetyl-CoA, cysteine, and methylmalonyl-CoA. Thioester-templated reaction intermediates and products are typically characterized by quantifying radioactive substrates, either enzyme bound or chemically hydrolyzed. In contrast, the MS-based methodology described here provides semiquantifiable ratios of free enzyme, intermediate, and product occupancy and reveals that certain substrates result in a >50% formation of nonproductive intermediates. 相似文献
12.
13.
14.
R. Dylewicz A. Z. Khokhar R. Wasielewski P. Mazur F. Rahman 《Applied physics. B, Lasers and optics》2012,107(2):393-399
We describe the fabrication and characterization of a randomly etched gallium nitride (GaN) surface for enhancing light extraction from light-emitting diodes. Our technique uses silica spheres as nano-targets in a sputter-etch process and produces a fine-grained surface with features around 35 nm. The textured surface layer acts as a graded refractive index layer with antireflection properties. Measurements show that photoluminescence intensity from such treated surfaces on a GaN LED wafer increases 2.2?times over that from pristine surfaces. These findings are also supported by computer modelling studies described here. 相似文献
15.
16.
17.
Different methods for the interpretation of linear dichroic spectra of molecules incorporated in uniaxial matrices are discussed. A method based on the combination of both polarized absorption and emission measurements is described for the resolution of absorption and emission spectra into their different polarized components, and for the investigation of molecular distributions in the oriented matrix. The distributions of some planar molecules of different shapes incorporated in stretched polyethylene films are presented. 相似文献
18.
Rafa Lewandkw Miosz Grodzicki Piotr Mazur Antoni Ciszewski 《Surface and interface analysis : SIA》2021,53(1):118-124
Al2O3 insulator layers were deposited step by step by the physical vapor deposition (PVD) method onto gallium nitride in the wurtzite form, n‐type and (0001)‐oriented. The substrate surface and the early stages of Al2O3/n‐GaN(0001) interface formation were characterized in situ under ultra‐high vacuum conditions by X‐ray and ultraviolet photoelectron spectroscopy (XPS, UPS). The electron affinity (EA) of the substrate cleaned by annealing was 3.6 eV. Binding energies of the Al 2p (76.0 eV) and the O 1s (532.9 eV) confirmed the creation of the Al2O3 compound in the deposited film for which the EA was 1.6 eV. The Al2O3 film was found to be amorphous with a bandgap of 6.9 eV determined from the O 1s loss feature. As a result, the calculated Al2O3/n‐GaN(0001) valence band offset (VBO) is ?1.3 eV and the corresponding conduction band offset (CBO) 2.2 eV. 相似文献
19.
D.?Yu.?VelikovskiiEmail author M.?M.?Mazur A.?A.?Pavlyuk V.?E.?Pozhar S.?F.?Solodovnikov L.?I.?Yudanova 《Physics of Wave Phenomena》2015,23(1):58-62
A KLuW laser crystal is investigated as an acousto-optic material. It is shown that the crystal can be used in devices for controlling high-power laser radiation. Obtainable characteristics of promising classical devices (modulator, deflector) are estimated. A possibility of developing a new type of device for both lasing and Q-switching is analyzed. 相似文献
20.
Three-dimensional texture analysis is now an efficient tool for examining polycrystalline materials. Owing to its widespread application, the possibilities and restrictions of determining the orientation distribution function on the basis of various kinds of experimental data should be recognized. With this in mind, the paper considers pole figures featuring reflection coincidence. 相似文献