首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   80篇
  免费   4篇
化学   72篇
晶体学   2篇
数学   2篇
物理学   8篇
  2023年   2篇
  2022年   2篇
  2021年   2篇
  2020年   3篇
  2019年   3篇
  2018年   3篇
  2017年   1篇
  2016年   4篇
  2015年   4篇
  2014年   1篇
  2013年   6篇
  2012年   7篇
  2011年   6篇
  2010年   5篇
  2009年   3篇
  2008年   3篇
  2007年   3篇
  2006年   1篇
  2005年   4篇
  2004年   1篇
  2003年   2篇
  2001年   2篇
  1996年   1篇
  1994年   3篇
  1993年   1篇
  1989年   1篇
  1988年   1篇
  1985年   1篇
  1984年   1篇
  1980年   2篇
  1979年   1篇
  1977年   1篇
  1974年   1篇
  1957年   2篇
排序方式: 共有84条查询结果,搜索用时 10 毫秒
21.
Glycidyl methacrylate was copolymerized with tert-butyl acrylate in bulk at 60°C using benzoyl peroxide as free radical initiator. The copolymer composition was determined by chemical analysis as well as from 13C-NMR data. The monomer reactivity ratios were calculated by using the YBR method. The number average sequence length of the copolymers was determined from 13C-NMR data and compared with those obtained from reactivity ratios. The intrinsic viscosity of the copolymers was determined in DMF, and thermal stability as well as mechanism of thermal degradation of the copolymers were evaluated.  相似文献   
22.
Poly(2-chloroethyl α-chloroacrylate) was synthesized by radical initiation, and its microstructure was evaluated using carbon-13 NMR. Methyl methacrylate (M1) and 2-chloroethyl α-chloroacrylate (M2) were copolymerized in toluene at 55°C using azobisisobutyronitrile as initiator. The reactivity ratios are 0.37 ± 0.28 and 1.21 ± 2.26, The thermal properties of these copolymers have also been reported.  相似文献   
23.
A new, efficient, and diastereoselective one-pot synthesis of cis-fused pyrano and furano chromenylaminoanthraquinones through hetero Diels–Alder reaction of 1-aminoanthraquinone and salicylaldehydes with electron-rich alkenes such as 3,4-dihydro-2H-pyran, 2,3-dihydrofuran, and ethyl vinyl ether under mild conditions is reported.  相似文献   
24.
25.
The title salts, 4‐chloroanilinium hydrogen phthalate (PCAHP), C6H7ClN+·C8H5O4, 2‐hydroxyanilinium hydrogen phthalate (2HAHP), C6H8NO+·C8H5O4, and 3‐hydroxyanilinium hydrogen phthalate (3HAHP), C6H8NO+·C8H5O4, all crystallize in the space group P21/c. The asymmetric unit of 2HAHP contains two independent ion pairs. The hydrogen phthalate ions of 2HAHP and 3HAHP show a short intramolecular O—H...O hydrogen bond, with O...O distances ranging from 2.3832 (15) to 2.3860 (14) Å. N—H...O and O—H...O hydrogen bonds, together with short C—H...O contacts in PCAHP and 3HAHP, generate extended hydrogen‐bond networks. PCAHP forms a two‐dimensional supramolecular sheet extending in the (100) plane, whereas 2HAHP has a supramolecular chain running parallel to the [100] direction and 3HAHP has a two‐dimensional network extending parallel to the (001) plane.  相似文献   
26.
27.
Cyclohexyl α-chloroacrylate (CCA) was polymerized by radical anionic and γ-radiation initiation. The anionic polymerization of cyclohexyl α-chloroacrylate gave moderately isotactic polymer in toluene and syndiotactic-rich polymer in THF. Poly(cyclohexyl α-chloroacrylate) (PCCA) was found to undergo two-stage weight loss in thermogravimetric analysis, and the first-stage weight loss was attributed to the lactonization reaction. PCCA degraded under γ-radiation, and the radiation yields of crosslinking and scission, G x and G s, were 0.6 and 3.8, respectively.  相似文献   
28.
In the salt 1‐methylpiperazine‐1,4‐diium bis(dihydrogen phosphate), C5H13N22+·2H2PO4, (I), and the solvated salt 2‐(pyridin‐2‐yl)pyridinium dihydrogen phosphate–orthophosphoric acid (1/1), C10H9N2+·H2PO4·H3PO4, (II), the formation of O—H...O and N—H...O hydrogen bonds between the dihydrogen phosphate (H2PO4) anions and the cations constructs a three‐ and two‐dimensional anionic–cationic network, respectively. In (I), the self‐assembly of H2PO4 anions forms a two‐dimensional pseudo‐honeycomb‐like supramolecular architecture along the (010) plane. 1‐Methylpiperazine‐1,4‐diium cations are trapped between the (010) anionic layers through three N—H...O hydrogen bonds. In solvated salt (II), the self‐assembly of H2PO4 anions forms a two‐dimensional supramolecular architecture with open channels projecting along the [001] direction. The 2‐(pyridin‐2‐yl)pyridinium cations are trapped between the open channels by N—H...O and C—H...O hydrogen bonds. From a study of previously reported structures, dihydrogen phosphate anions show a supramolecular flexibility depending on the nature of the cations. The dihydrogen phosphate anion may be suitable for the design of the host lattice for host–guest supramolecular systems.  相似文献   
29.
30.
Jagan  R.  Sathya  D.  Sivakumar  K. 《Crystallography Reports》2021,66(6):991-999
Crystallography Reports - In title compound bis(2,5-dichloroanilinium) sulfate, the equally disordered sulfate anion occupies 2-fold rotation axis with equivalent component generated through the...  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号