全文获取类型
收费全文 | 199篇 |
免费 | 11篇 |
国内免费 | 63篇 |
专业分类
化学 | 267篇 |
力学 | 5篇 |
物理学 | 1篇 |
出版年
2022年 | 3篇 |
2021年 | 2篇 |
2020年 | 1篇 |
2019年 | 3篇 |
2018年 | 3篇 |
2017年 | 5篇 |
2016年 | 4篇 |
2015年 | 4篇 |
2014年 | 11篇 |
2013年 | 16篇 |
2012年 | 11篇 |
2011年 | 12篇 |
2010年 | 12篇 |
2009年 | 13篇 |
2008年 | 13篇 |
2007年 | 12篇 |
2006年 | 16篇 |
2005年 | 14篇 |
2004年 | 24篇 |
2003年 | 6篇 |
2002年 | 7篇 |
2001年 | 18篇 |
2000年 | 9篇 |
1999年 | 4篇 |
1998年 | 2篇 |
1997年 | 5篇 |
1996年 | 3篇 |
1995年 | 6篇 |
1994年 | 5篇 |
1993年 | 12篇 |
1992年 | 5篇 |
1991年 | 2篇 |
1990年 | 4篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
排序方式: 共有273条查询结果,搜索用时 15 毫秒
81.
82.
简要介绍含二苯酮基的大分子光敏引发剂的合成制备、引发聚合机理及应用方面的研究进展情况。 相似文献
83.
The cationic polymerization of 1, 3-pentadiene was initiated by the organic azide/Et_2 AlClinitiating system in CH_2Cl_2 and n-hexane. The polymerizations were also carried out in parallelwith organic chloride/Et_2AlCl and Et_2 AlCl alone for comparison. The Et_2 AlCl- induced polymer-ization gives a low yield while the polymerization initiated by organic chloride/Et_2 AlCl producesmainly insoluble product. In contrast, the polymerization with azide/Et,AlCl has a high conver-sion and the resulting polymer having a high molecular weight is totally soluble. The SEC spectraof the polymers have clearly shown the differences between these initiating systems. 相似文献
84.
Fumio Hamazu Sumio Akashi Tatsuya Koizumi Toshikazu Takata Takeshi Endo 《Journal of polymer science. Part A, Polymer chemistry》1993,31(4):1023-1028
Various p-substituted benzyl p-hydroxyphenyl methyl sulfonium salts ( 2 ) were synthesized and their initiator activities were evaluated in bulk polymerization of glycidyl phenyl ether (PGE). The order of the activity was found to be 2b (X = CH3) > 2a (X = H) ≈ 2c (X = Cl) > 2d (X = NO2), indicating that the introduction of an electron-donating group enhanced the activity. In Hammett's plots, the logarithm of the ratio of the polymerization rates (log kx/kH) was correlated with σ+ρ better than with σp and a negative ρ+ value (-1.18) was obtained. Reaction of 2a with benzyl mercaptan mainly gave dibenzyl sulfide and p-hydroxyphenyl methyl sulfide. The obtained results seemed to demonstrate that the OH group of the aryl group yielded no proton as initiator for the polymerization, whereas the benzyl group caused the polymerization, which was initiated by the corresponding benzyl cation formed by C? S bond cleavage. © 1993 John Wiley & Sons, Inc. 相似文献
85.
The ring-opening polymerization of 1,4-dioxan-2-one (PDO) was carried out by lanthanum tris(2,6-di-tert-butyl-4-methylphenolate) (La(OAr)3) as novel single component initiator. The influences of polymerization reaction temperature and the molar ratio of monomer to initiator on the monomer conversion and molecular weight of poly(1,4-dioxan-2-one) (PPDO) were explored. PPDO with high viscosity average molecular weight of 1.95 × 105 can be prepared at 40℃ when [PDO]/ [La(OAr)3] molar ratio was 800. Mechanism investigation shows that the polymerization proceeds through a "coordinationinsertion" mechanism with selective rupture of acyl-oxygen bond of PDO. 相似文献
86.
The polymerization of metyl methacrylate (MMA) was studied in detail by use of CuCI/L as a catalyst and cholesteryl chloroformate (CC) as an initiator. It was found that the atom transfer radical polymerization of MMA could proceed when L equals to a multidentate aliphatic amine ligand, N,N,N‘,N“,N“-penta(methyl acrylate)diethylenetriamine (MA5-DETA), and no polymerization was occurred while L=2,2‘-bipyridine and 1,10phenanthroline. The linear proportionality of the molecular weights to the conversions and straight lines observed in ln[M]0/[M] versus time plots indicated that the present polymerization system had the typical controlled polymerization characteristics. 相似文献
87.
ATOM TRANSFER RADICAL POLYMERIZATION OF 2,5-BIS[(4-HEXYLOXYPHENYL)OXYCARBONYL]STYRENE 总被引:2,自引:0,他引:2
A side-on liquid crystalline monomer, 2,5-bis[(4-hexyloxyphenyl)oxycarbonyl]styrene) (HPCS), was successfully polymerized via atom transfer radical polymerization (ATRP). The polymerization was catalyzed by CuBr/PMDETA in chlorobenzene at 90℃ with (1-bromoethyl)benzene as the initiator. The polymers have narrow MWD. It is the second example of mesogen-jacketed liquid crystalline polymer (MJLCP) prepared by ATRP. 相似文献
88.
含偶氮聚四氢呋喃的合成及分解 总被引:1,自引:0,他引:1
<正> 本文以4,4′-偶氮二异氰基戊酰氯(ACVCl)与SbCl_5引发体系,低温下进行THF聚合,合成出主链中含有一个偶氮基的聚四氢呋喃(简称AZO-PTHF)。该聚合物中的AZO基和通常低分子偶氮化合物一样可在受热时发生分解反应,生成大分子游离基,因此可作为高分子引发剂引发乙烯基单体聚合。ESR波谱分析表明,该聚合物在40°C左右热分解产生游离基。 相似文献
89.
以数均分子量为6000的聚乙二醇为引发剂,以辛酸亚锡为催化剂引发丙交酯开环,再用甲基丙烯酸酐进行封端生成大分子单体.然后将大分子单体和α-环糊精混合,分别用维生素C和硫酸亚铁与过硫酸铵组成的氧化还原引发剂引发聚合,得到了两种不同结构的超分子结构水凝胶.用1HNMR,FTIR,TGA和XRD等分析测试手段对大分子单体及形成的水凝胶进行了表征.流变仪测试结果表明,该水凝胶固化时间合适,并具有可注射性. 相似文献
90.