全文获取类型
收费全文 | 104篇 |
免费 | 8篇 |
国内免费 | 17篇 |
专业分类
化学 | 85篇 |
晶体学 | 2篇 |
力学 | 1篇 |
数学 | 14篇 |
物理学 | 27篇 |
出版年
2022年 | 1篇 |
2021年 | 3篇 |
2019年 | 1篇 |
2016年 | 1篇 |
2015年 | 2篇 |
2014年 | 5篇 |
2013年 | 11篇 |
2012年 | 2篇 |
2011年 | 3篇 |
2010年 | 1篇 |
2009年 | 3篇 |
2008年 | 5篇 |
2007年 | 2篇 |
2006年 | 3篇 |
2005年 | 3篇 |
2004年 | 2篇 |
2001年 | 2篇 |
2000年 | 3篇 |
1999年 | 3篇 |
1998年 | 2篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1995年 | 2篇 |
1994年 | 2篇 |
1992年 | 2篇 |
1991年 | 3篇 |
1990年 | 3篇 |
1989年 | 3篇 |
1988年 | 1篇 |
1987年 | 4篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1981年 | 3篇 |
1978年 | 1篇 |
1977年 | 2篇 |
1976年 | 5篇 |
1975年 | 3篇 |
1974年 | 4篇 |
1973年 | 3篇 |
1972年 | 1篇 |
1971年 | 2篇 |
1969年 | 4篇 |
1968年 | 2篇 |
1967年 | 5篇 |
1966年 | 3篇 |
1965年 | 1篇 |
1962年 | 2篇 |
排序方式: 共有129条查询结果,搜索用时 15 毫秒
61.
将纳米金(NG)电沉积在有序介孔碳(OMC)修饰玻碳电极表面,并将L-半胱氨酸(L-Cys)自组装至OM C/NG修饰电极表面,制备了OM C/NG/L-Cys修饰电极。采用透射电子显微镜考察了OM C的结构,扫描电子显微镜研究了OMC/NG/L-Cys修饰电极的表面形貌。考察了Cu2+在该修饰电极上的电化学行为,优化了Cu2+的测定条件。在最优条件下,溶出峰峰电流与Cu2+浓度在0.05~6.0μmol/L范围内呈良好线性关系,检出限为0.03μmol/L(S/N=3)。方法用于河水样品分析,其加标回收率在92.7%~101.6%之间。 相似文献
62.
Summary
Spectrophotometric Microgram Determination of Copper in Organic Compounds by Wet or Oxygen Flask Combustion
A spectrophotometric method for the microgram (2–30 ppm) determination of copper in organic compounds after wet digestion or oxygen flask combustion has been developed. The copper content is determined through the formation of the molybdenum blue complex, which is formed by the addition of 1 ml of each of 1% KCN, 1% phosphomolybdic acid and 1M HCl solutions, in the order mentioned. The absorbance is measured at 725 nm. A series of 10 compounds with 10–40% copper gave highly satisfactory results. The total average error is ±0.05% and the overall standard deviation value is 0.220. The method described is rapid, simple and accurate; the reagents required are cheap and readily available. 相似文献
63.
The X-band ( x ; 9.4 v GHz) electron spin resonance (ESR) spectra of the un-doped isotopically enriched lithium tetraborate (LTB) Li 2 B 4 O 7 single crystals, irradiated by thermal neutrons (fluences | n =2.74 ‐ 10 15 1 1.79 v ‐ 10 18 v cm m 2 ) were investigated at 300 and 77 v K. The LTB crystals of high chemical purity and optical quality with different isotope compositions ( 6 Li 2 10 B 4 O 7 , 6 Li 2 11 B 4 O 7 , 7 Li 2 10 B 4 O 7 and 7 Li 2 11 B 4 O 7 ) were grown by Czochralski technique. The thermal neutrons (the total quantity >90%) with fluence near 10 18 v cm m 2 induce at least 4 different types of stable paramagnetic centers in the Li and B isotopically enriched LTB crystals. The ESR spectra, electron structure and efficiency of generation for centers, induced by thermal neutrons, essentially depend on neutron fluence and isotope composition of the LTB crystals. The local symmetry and the spin Hamiltonian parameters of the observed paramagnetic centers were determined and their electron structure were established. The possible models and formation mechanism of the radiation defects, induced by thermal neutrons in the LTB lattice, are proposed. 相似文献
64.
Statistical distributions of the frequencies of OH vibrations calculated from the experimental Raman spectra of HOD molecules over the temperature range of 10–200 C using the recently developed deconvolution technique have been analysed in the framework of fluctuation theory of hydrogen bonding. Two temperature independent functions that are the basis of the Zhukovsky theory for describing the temperature transformation of frequency distribution functions of OH vibrations in a statistical ensemble of O—H…O bonds were established and analytically approximated. This made it possible to reconstruct the entire set of initial spectra and to extrapolate their forms to a wider temperature range. These results support the continuum model of liquid water structure. 相似文献
65.
HAN Guo-qiang YA O Hai-lou 《数学季刊》2014,(2):244-246
Let K be an algebraically closed field and A be a finite dimensional algebra over K. In this paper we give a classification of biserial incidence algebras with quiver methods. 相似文献
66.
67.
68.
69.
A.YA. Dorofeev L.S. Kazarin V.M. Sidelnikov M.E. Tuzhilin 《Designs, Codes and Cryptography》2005,37(3):391-404
We consider a finite matrix group
with 34· 216 elements, which is a subgroup of the infinite group
, where
is the regular representation of the quaternion group and C is a matrix that transforms the regular representation Q to its cellwise-diagonal form. There is a number of ways to define the matrix C. Our aim is to make the group
similar in a certain sense to a finite group. The eventual choice of an appropriate matrix C done heuristically.
We study the structure of the group
and use this group to construct spherical orbit codes on the unit Euclidean sphere in R8. These codes have code distance less than 1. One of them has 32· 28 = 2304 elements and its squared Euclidean code distance is 0.293.
Communicated by: V. A. Zinoviev 相似文献
70.