全文获取类型
收费全文 | 270篇 |
免费 | 2篇 |
国内免费 | 2篇 |
专业分类
化学 | 184篇 |
晶体学 | 6篇 |
力学 | 6篇 |
数学 | 40篇 |
物理学 | 38篇 |
出版年
2022年 | 11篇 |
2021年 | 8篇 |
2020年 | 11篇 |
2019年 | 12篇 |
2018年 | 4篇 |
2017年 | 4篇 |
2016年 | 7篇 |
2015年 | 12篇 |
2014年 | 14篇 |
2013年 | 29篇 |
2012年 | 16篇 |
2011年 | 19篇 |
2010年 | 25篇 |
2009年 | 16篇 |
2008年 | 21篇 |
2007年 | 15篇 |
2006年 | 10篇 |
2005年 | 10篇 |
2004年 | 6篇 |
2003年 | 7篇 |
2002年 | 3篇 |
2001年 | 1篇 |
2000年 | 5篇 |
1999年 | 2篇 |
1996年 | 2篇 |
1995年 | 2篇 |
1993年 | 1篇 |
1989年 | 1篇 |
排序方式: 共有274条查询结果,搜索用时 0 毫秒
161.
162.
M. M. Quazi M. A. Fazal A. S. M. A. Haseeb Farazila Yusof H. H. Masjuki A. Arslan 《固体与材料科学评论》2016,41(2):106-131
Aluminum (Al) and its alloys have widespread engineering applications because of their higher strength to weight ratio, ductility, and formability. However, in various applications, mechanical properties such as hardness, corrosion, wear, and fatigue resistance are prerequisite at near surface regions. Such localized modification without affecting the bulk phase can be performed by various surface-engineering approaches including electro-deposition, physical and chemical vapor depositions, thermal spraying, plasma spraying, and organic polymeric coatings. Delamination failure of such coatings from the substrate is often inevitable due to the difference in film-to-substrate elastic modulus associated with the aforementioned processes. Recently, researchers have adopted a new approach of laser surface engineering to modify the near surface regions of metallic substrate by laser beams resulting in superior mechanical properties with the formation of novel microstructures. In this article, the recent developments in the surface modification of Al and its alloy by laser treatment are reviewed. Processing parameters and resulting microstructures of Al and its alloys are briefly summarized, along with their impact on mechanical properties. Finally, this article concludes future research directions. 相似文献
163.
164.
165.
A sensitive method for the determination of estradiol is presented that is based on an electrode modified with multi-walled carbon nanotubes (MWNTs) along with an ionic liquid. The resulting electrode showed more sensitive voltammetric response to estradiol than other electrodes modified with MWNTs. The peak current for estradiol is linearly related to concentration over two decades, and the limit of detection is 5 nM. The method was applied to the determination of estradiol in rabbit blood serum and in environmental waters. The recoveries were 95.3–104.0% and 97.0–104.7%, respectively. 相似文献
166.
Mo(CO)6 was reacted with the Schiff base ligand obtained by condensation reaction of 2‐acetyl‐ or benzoylpyridine with poly(propylene glycol)bis(2‐aminopropyl ether) to obtain polymeric, dinuclear metal tetracarbonyl compounds. The long‐chain Schiff base complexes are highly soluble even in non‐polar solvents such as petroleum ether, diethyl ether and n‐hexane. These complexes, as free‐radical initiators, afforded methyl methacrylate polymerization in chlorinated solvents. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
167.
168.
The reaction between phenylmagnesium bromide and hexachlorocyclotriphophazene (N 3 P 3 Cl 6 ) ( 1 ) was reinvestigated for the synthesis of hexaphenylcyclotriphosphazene (N 3 P 3 Ph 6 ) ( 2 ) in high yield. The reaction is complete within two weeks at room temperature using toluene as solvent. When the reactants (PhMgBr and N 3 P 3 Cl 6 ) were employed in a 6:1, 36:1 and 72:1 molar ratio, compound 2 was obtained in 2.6%, 14%, and 33.4% yield, respectively. The formation of N 3 P 3 Cl 6 ( 2 ) during the reaction was followed by thin-layer chromatography. Compound 2 was characterized by elemental analysis, IR, UV-VIS, 1 H, 13 C, and 31 P NMR spectroscopy as well as by mass spectrometry. 相似文献
169.
Margarita G. Ilyina Edward M. Khamitov Rail N. Galiakhmetov Ildar A. Mustafin Arslan F. Akhmetov Regina Kh. Shayakhmetova Akhat G. Mustafin 《中国化学会会志》2020,67(1):33-40
In the present work, the composition and relative density of light gasoil of catalytic cracking (LGCC) were studied using chromato-mass-spectrometry and its key physical properties were numerically simulated using molecular dynamics. We have studied the distribution of hydrocarbon compounds over narrow fractions of LGCC. We have applied the ASTM D2892-11a standard distillation to find the component composition of LGCC and its narrow fractions obtained from a mixture of West Siberian oils. Molecular dynamics simulations were performed using the GROMOS96 54a7 force field for the ensemble of constant number of particles (N), pressure (P) and temperature (T) (NPT) ensemble under the constant temperature and constant pressure conditions. The topologies of the structures under study were generated by the automated topology builder (ATB) service. Both the chromatographic mass spectrometry experiments and molecular dynamics simulations indicate the contents of aromatic hydrocarbons in LGCC from the mixture of West Siberian oils up to 80 wt%. 相似文献
170.
The synthesis and characterization of two donor acceptor type conjugated polymers were investigated. Electrochemical properties were examined by cyclic voltammetry, spectroelectrochemistry and kinetic studies. The increase in the alkyl chain length attached to the fluorene unit was investigated in terms of electrochemical properties. The synthesis was carried out via Stille coupling of 4,7-dibromo-4′-(tert-butyl)spiro[benzo[d]imidazole-2,1′ cyclohexane] and 2,5-bis(tributylstannyl)thiophene with 9,9-dihexyl-9H fluorine (P1) and 9,9-didodecyl-9H fluorene (P2) respectively. Both polymers were neutral state green polymers. They had optical band gaps of 1.55 and 1.47 eV respectively. Increasing the chain length resulted in an increase in solubility and processibility of the polymer. Polymers are multichromic, revealing colors from neutral state green to doped state blue. 相似文献