全文获取类型
收费全文 | 454篇 |
免费 | 3篇 |
国内免费 | 3篇 |
专业分类
化学 | 318篇 |
晶体学 | 4篇 |
力学 | 10篇 |
数学 | 19篇 |
物理学 | 109篇 |
出版年
2022年 | 3篇 |
2021年 | 6篇 |
2020年 | 4篇 |
2018年 | 4篇 |
2017年 | 4篇 |
2016年 | 3篇 |
2015年 | 2篇 |
2014年 | 10篇 |
2013年 | 14篇 |
2012年 | 25篇 |
2011年 | 17篇 |
2010年 | 41篇 |
2009年 | 34篇 |
2008年 | 10篇 |
2007年 | 13篇 |
2006年 | 9篇 |
2005年 | 11篇 |
2004年 | 18篇 |
2003年 | 12篇 |
2002年 | 6篇 |
2001年 | 1篇 |
2000年 | 6篇 |
1999年 | 2篇 |
1998年 | 2篇 |
1997年 | 7篇 |
1996年 | 2篇 |
1995年 | 2篇 |
1994年 | 2篇 |
1993年 | 6篇 |
1992年 | 1篇 |
1991年 | 14篇 |
1990年 | 16篇 |
1989年 | 23篇 |
1988年 | 15篇 |
1987年 | 21篇 |
1986年 | 4篇 |
1985年 | 3篇 |
1984年 | 1篇 |
1983年 | 3篇 |
1982年 | 4篇 |
1981年 | 3篇 |
1979年 | 5篇 |
1978年 | 2篇 |
1977年 | 18篇 |
1976年 | 7篇 |
1975年 | 9篇 |
1974年 | 11篇 |
1973年 | 17篇 |
1972年 | 5篇 |
1971年 | 1篇 |
排序方式: 共有460条查询结果,搜索用时 15 毫秒
1.
2.
对不同的本底真空条件下,采用甚高频等离子体增强化学气相沉积技术沉积的氢化微晶硅(μc_Si∶H)薄膜中的氧污染问题进行了比较研究.对不同氧污染条件下制备的薄膜样品的x射线光电子能谱与傅里叶变换红外吸收光谱测量结果表明:μc_Si∶H薄膜中,氧以Si—O,O—O和O—H三种不同的键合模式存在,不同的键合模式源自不同的物理机理.μc_Si∶H薄膜的Raman光谱、电导率与激活能的测量结果进一步显示:沉积过程中氧污染程度的不同,对μc_Si∶H薄膜的结构特性与电学特性产生显著影响;而不同氧污染对μc_Si∶H薄膜电学特性的影响不同于氢化非晶硅(a_Si:H)薄膜.
关键词:
氢化微晶硅薄膜
甚高频等离子体增强化学气相沉积
氧污染 相似文献
3.
4.
V. V. Kuznetsov A. Pal'ma A. é. Aliev M. Fernandes N. S. Prostakov A. V. Varlamov 《Chemistry of Heterocyclic Compounds》1993,29(6):671-675
The cydization of 1-allyl-1-arylaminocyclohexanes under conditions of acid catalysis afforded 1,2,3,4-tetrahydro-4-methylspiro [quinoline-2-cyclohexanes] methyl (methoxy)-substituted in the phenylene ring. Their mono- and dinitro derivatives were synthesized, and their structure was established. Propositions on the direction of the nitration reaction of these heterocyclic compounds were expressed.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 784–788, June, 1993. 相似文献
5.
Riedl Z Kövér P Soós T Hajós G Egyed O Fábián L Messmer A 《The Journal of organic chemistry》2003,68(14):5652-5659
2-Arylsulfanyl and 2-benzylsulfanylpyridinium N-arylimides (2) easily prepared from 3-aryltetrazolopyridinium salts (1) with aryl and benzylthiolates, respectively, reacted with various dipolarophiles yielding cycloadducts that underwent transformation to give tetrahydropyrrolo[3,2-b]pyridines (5, 6, and 8) in good yields. A similar rearrangement (formation of 15) was also observed in the case of parent derivatives being unsubstituted in position 2 (12). The abscence of any significant solvent effect, comparison of the sulfur and non-sulfur analogues, as well as the stereoselective nature of the observed ring transformation seem to support a sigmatropic mechanism. Structure elucidation of the products has been carried out by single-crystal X-ray diffraction and (1)H NMR experiments. 相似文献
6.
7.
A. é. Mistryukov I. D. Sadekov V. S. Sergienko G. M. Abakarov M. A. Porai-Koshits A. A. Shneider A. D. Garnovskii 《Chemistry of Heterocyclic Compounds》1989,25(12):1407-1409
The crystal and molecular structure of 2-phenylbenzotellurazole is determined by x-ray methods. The heterocyclic fragment of the molecule is planar. The dihedral angle between planes of the heterocycle and the 2-phenyl substituent is 31.2. Somewhat shortened Te-N intermolecular ocntacts (3.43 å) are seen in the crystal. These do not substantially affect the physical properties of the compound.For Communication 3, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1690–1692, December, 1989. 相似文献
8.
It has been established that 2-(tert-butyl)-3-hydroxy-3-(4-chlorophenyl)isoindolinone and N-(tert-Alkyl)-2-aroylbenzamides are dealkylated in concentrated sulfuric acid to give 3-hydroxy-3-arylisoindolinones. The reaction is realizable. only when there is a tert-alkyl group attached to the nitrogen atom. The reaction mechanism is discussed on the basis of data on the change with time in the electronic spectra of the investigated compounds in concentrated sulfuric acid and a comparison with the spectra of model structures.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 763–765, June, 1977. 相似文献
9.
O. S. Attaryan G. V. Asratyan G. A. éliazyan G. A. Panosyan F. S. Kinoyan E. G. Darbinyan 《Chemistry of Heterocyclic Compounds》1989,25(4):414-420
The phase-transfer catalyzed (PTC) alkylation of pyrazoles and 1,2,4-triazole with cis- and trans-1,4-dichloro-2-butenes (DCB) has been examined. The monoalkylation products of pyrazoles with cis-DCB are bicyclic salts formed by intramolecular cyclization of the intermediate cis-1-(4-chloro-2-butenyl)pyrazoles. The corresponding trans-compounds are incapable of cyclization, but on prolonged standing they undergo intermolecular polyquaternization. Both cis- and trans-DCB undergo phase-transfer catalyzed reaction with 1,2,4-triazole to give polymeric quaternary salts. Conditions have been worked out for the dehydrochlorination of 1-(4-chloro-2-butenyl)azoles to 1-(butadien-2-yl)azoles.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 497–503, April, 1989. 相似文献
10.
G. I. Khaskin A. B. Rozhenko E. G. Khil'chevskaya T. é. Bezmenova‡ 《Chemistry of Heterocyclic Compounds》1988,24(10):1180-1184
Reaction of trans-3-chloro-A-aminothiolane 1,1-dioxide hydrochloride with aryl isothiocyanates gives, according to the base involved, cis-perhydrothieno[3,4-d]imidazole-2-thione 5,5-dioxides or the hitherto undescribed cis-2-aryliminoperhydrothieno 3,4-d] thiazole 5,5-dioxides.For Part 2, see [1].Deceased.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1420–1423, October, 1988. 相似文献