全文获取类型
收费全文 | 386篇 |
免费 | 26篇 |
专业分类
化学 | 362篇 |
晶体学 | 3篇 |
力学 | 1篇 |
数学 | 9篇 |
物理学 | 37篇 |
出版年
2023年 | 1篇 |
2022年 | 6篇 |
2021年 | 3篇 |
2020年 | 16篇 |
2019年 | 13篇 |
2018年 | 8篇 |
2017年 | 3篇 |
2016年 | 13篇 |
2015年 | 16篇 |
2014年 | 14篇 |
2013年 | 27篇 |
2012年 | 41篇 |
2011年 | 37篇 |
2010年 | 17篇 |
2009年 | 8篇 |
2008年 | 32篇 |
2007年 | 18篇 |
2006年 | 16篇 |
2005年 | 25篇 |
2004年 | 16篇 |
2003年 | 10篇 |
2002年 | 10篇 |
2001年 | 2篇 |
2000年 | 2篇 |
1999年 | 7篇 |
1998年 | 2篇 |
1997年 | 5篇 |
1996年 | 6篇 |
1995年 | 2篇 |
1994年 | 1篇 |
1993年 | 2篇 |
1992年 | 1篇 |
1990年 | 2篇 |
1987年 | 3篇 |
1986年 | 5篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1982年 | 4篇 |
1981年 | 1篇 |
1980年 | 3篇 |
1979年 | 4篇 |
1978年 | 2篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1974年 | 1篇 |
1973年 | 2篇 |
排序方式: 共有412条查询结果,搜索用时 10 毫秒
151.
Shohei Nishitani Prof. Dr. Ryo Sekiya Prof. Dr. Takeharu Haino 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(2):679-683
The development of chiral nanographenes has mostly been carried out by bottom-up methods and examples of species developed by the post-modification of nanographenes prepared by top-down methods remain limited. We show that the attachment of chiral functional groups onto the edge of nanographenes generates chirality on the surface. X-ray diffraction analysis and DFT calculations indicate that the chirality of the functional groups is transferred to the surface via steric interactions from the chiral center through the five-membered cyclic imide to the nanographene edge. The exciton coupling between the p-bromophenyl groups confirms that the functional groups are arranged on the armchair edges at distances that permit exciton coupling, which provides information about their relative orientation. These pieces of information help to elucidate the edge structure of nanographenes prepared by top-down methods. 相似文献
152.
A cholesterol-conjugated fluorescence Zn(2+) sensor based on the fluorescein platform was designed and synthesized. The cholesterol moiety is essential for localizing the Zn(2+) sensor to the cell membrane, allowing the sensor to probe changes in the Zn(2+) concentration in a localized area of the cell. 相似文献
153.
Haketa Y Sakamoto S Chigusa K Nakanishi T Maeda H 《The Journal of organic chemistry》2011,76(13):5177-5184
Dipyrrolyldiketone BF(2) complexes acting as acyclic anion receptors form supramolecular assemblies with structures and properties that are dependent on the pyrrole β-substituents. In particular, although β-alkyl substituents interfered with the formation of stable gel states, the introduction of fluorine moieties induced a stable supramolecular gel when compared to that of β-unsubstituted receptor. 相似文献
154.
Asakura N Fujimoto S Michihata N Nishii K Imagawa H Yamada H 《The Journal of organic chemistry》2011,76(23):9711-9719
A reliable method for synthesizing each enantiomer of the hexahydroxydiphenoyl (HHDP) compounds has been developed. The synthesis involved atropselective construction of the aryl-aryl bond of the HHDP compounds. This construction relied on the CuCl(2)·n-BuNH(2)-mediated intramolecular coupling of bis(4-O-benzylgallate) on two simple chiral auxiliaries, both of which were derived from l-(+)-tartaric acid. The coupling reaction realized complete or near-perfect atropselectivity. The two auxiliaries induced opposite axial chirality despite their identical origin. The diastereoselectivities of these couplings were probably controlled kinetically. Modifications of the free phenolic hydroxy groups and the carbonyl groups in the resulting HHDP compounds demonstrated the potential derivatization of a wide variety of HHDP analogues. 相似文献
155.
Tsuyoshi Miura Shohei NishidaAkira Masuda Norihiro TadaAkichika Itoh 《Tetrahedron letters》2011,52(32):4158-4160
Fluorous thiourea organocatalyst 3 promotes the Michael reaction of aldehydes with maleimides to afford the corresponding adducts in high yields with up to 99% ee. Fluorous organocatalyst 3 can be easily recovered as an insoluble precipitate from the reaction mixture by simple filtration and can be reused without significant loss of catalytic activity. 相似文献
156.
Nomura K Fukuda H Katao S Fujiki M Kim HJ Kim DH Zhang S 《Dalton transactions (Cambridge, England : 2003)》2011,40(31):7842-7849
Various half-sandwich titanium complexes containing iminoimidazolidide ligands, CpTiCl(2)[1,3-R(2)(CH(2)N)(2)C=N] (1a-d) [R = Ph (a), 2,6-Me(2)C(6)H(3) (b), cyclohexyl (c), (t)Bu (d)], have been employed as the catalyst precursors for ethylene polymerisation, syndiospecific styrene polymerisation, and copolymerisation of ethylene with 1-hexene in the presence of MAO cocatalyst; 1d showed the highest catalytic activity for ethylene polymerisation whereas 1b showed the highest activity for syndiospecific styrene polymerisation. 相似文献
157.
Okano K Ogino S Kawamoto M Yamashita T 《Chemical communications (Cambridge, England)》2011,47(43):11891-11893
We demonstrated the formation of a photoinduced surface relief grating using thin films comprising a photochromic molecular motor, 9-(2-phenyl-2,3-dihydro-cyclopenta[a]naphthalen-1-ylidene)-9H-fluorene. Results show that mass migration occurred by patterned light irradiation prepared from interfered laser beams and a photomask. 相似文献
158.
Hydrogel particles composed of poly(N-isopropylacrylamide) were used as a particulate steric stabilizer for the dispersion polymerization of styrene for the first time. The effects of the size and concentration of the hydrogel particles on the resultant polystyrene particles were investigated. As expected, the hydrogel particles indeed play the role of steric stabilizer for dispersion polymerization. Moreover, some of the resultant polystyrene particles were covered with hydrogel particles, which was confirmed by electron microscopy and X-ray photoelectron spectroscopy. 相似文献
159.
Bando Y Sakamoto S Yamada I Haketa Y Maeda H 《Chemical communications (Cambridge, England)》2012,48(17):2301-2303
Assemblies comprising anion complexes of π-extended oligopyrrole derivatives and counter cations, as well as those of anion-free receptor molecules, exhibited the formation of mesophases based on columnar structures using electrostatic and π-π interactions. 相似文献
160.
Clever GH Kawamura W Tashiro S Shiro M Shionoya M 《Angewandte Chemie (International ed. in English)》2012,51(11):2606-2609
Neatly wrapped up: alternately stacked square-planar platinum(II) complexes inside a dinuclear coordination cage were prepared to give a discrete and soluble Pt(5) -array of the Magnus' salt type. Characterization of the complex in solution was complemented by an X-ray crystal structure of {[Pt(pyridine)(4)]? [PtCl(4)](2) @Cage}; this structure showed the linear, pentanuclear array within the cages and their circular packing into a hollow tubular superstructure. 相似文献