全文获取类型
收费全文 | 1025篇 |
免费 | 22篇 |
国内免费 | 3篇 |
专业分类
化学 | 739篇 |
晶体学 | 4篇 |
力学 | 10篇 |
数学 | 38篇 |
物理学 | 259篇 |
出版年
2022年 | 5篇 |
2021年 | 9篇 |
2020年 | 8篇 |
2019年 | 11篇 |
2018年 | 6篇 |
2017年 | 5篇 |
2016年 | 14篇 |
2015年 | 11篇 |
2014年 | 14篇 |
2013年 | 48篇 |
2012年 | 39篇 |
2011年 | 75篇 |
2010年 | 35篇 |
2009年 | 41篇 |
2008年 | 56篇 |
2007年 | 62篇 |
2006年 | 53篇 |
2005年 | 54篇 |
2004年 | 46篇 |
2003年 | 37篇 |
2002年 | 34篇 |
2001年 | 34篇 |
2000年 | 27篇 |
1999年 | 16篇 |
1998年 | 14篇 |
1997年 | 10篇 |
1996年 | 13篇 |
1995年 | 15篇 |
1994年 | 19篇 |
1993年 | 9篇 |
1992年 | 16篇 |
1991年 | 13篇 |
1990年 | 16篇 |
1989年 | 12篇 |
1988年 | 14篇 |
1987年 | 11篇 |
1986年 | 9篇 |
1985年 | 22篇 |
1984年 | 12篇 |
1983年 | 4篇 |
1982年 | 10篇 |
1981年 | 13篇 |
1980年 | 12篇 |
1979年 | 13篇 |
1978年 | 6篇 |
1977年 | 6篇 |
1976年 | 6篇 |
1975年 | 6篇 |
1973年 | 10篇 |
1972年 | 3篇 |
排序方式: 共有1050条查询结果,搜索用时 884 毫秒
51.
Kanji Omura 《合成通讯》2013,43(5):877-885
Preparation and high resistance to acid hydrolysis of sterically hindered p-quinone monoketals 1a, 1b and 1c are described. Thermal stability of ketal alcohols 2a and 2b derived from 1a and 1c, respectively, is also mentioned. 相似文献
52.
53.
Yuichi Tominaga Takuya Kubo Kenji Sueyoshi Ken Hosoya Koji Otsuka 《Journal of polymer science. Part A, Polymer chemistry》2013,51(15):3153-3158
To synthesize the novel molecular‐ and pH‐stimulus‐responsive hydrogel, we prepared poly(ethylene glycol)‐based hydrogel containing ionic groups. We evaluated the fundamental swelling/shrinking properties of the hydrogels synthesized by various conditions. Decreasing the molecular weight of a crosslinker provided the increasing of the equilibrium swelling ratio. Also, the equilibrium swelling ratio was changed by the introduction of functional ionic monomers and its compositions. Furthermore, the swelling/shrinking behaviors of the hydrogels were affected by the environmental condition of aqueous solution, in fact the hydrogels were considerably shrunk (to one‐fifth volume) using a di‐ionic solute in the aqueous solution through the ionic interactions between the hydrogel and the solutes. Additionally, the specific shrinking to diamine compounds was also observed in response to pH change. These results clearly show the swelling/shrinking responsibility of the hydrogels toward the molecular recognitions and its pH conditions. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 3153–3158 相似文献
54.
55.
56.
Masami Kuriyama Satoko Tanigawa Yuki Kubo Yosuke Demizu Osamu Onomura 《Tetrahedron: Asymmetry》2010,21(11-12):1370-1373
A facile synthetic method toward optically active 3,3-disubstituted oxindoles with excellent enantioselectivity was achieved using chiral copper-catalyzed desymmetrization of prochiral 1,3-diols. The monotosylated product was transformed into oxindole derivatives efficiently. 相似文献
57.
Kazuyuki Kubo Hiroshi Nakazawa Hiroyasu Inagaki Tomoyuki Miyake Tsutomu Mizuta Katsuhiko Miyoshi 《Phosphorus, sulfur, and silicon and the related elements》2013,188(8-9):2159-2160
Treatment of [Cp*(CO) 2 M{P(NHPh)(OMe) 2 }]PF 6 (M = Fe and Ru) with NaNH 2 gives metallaiminophosphoranes, Cp*(CO) 2 M{P(NPh)(OMe) 2 }. The x-ray structures and reactivity of the complexes are reported. 相似文献
58.
Tatsuro Ouchi Hiroshi Sakamoto Masayasu Kubo Yoshifumi Hosaka Minoru Imoto 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(2):111-123
The radical polymerization of vinyl monomers initiated with several kinds of hydrophilic macromolecule was carried out in a magnetic field. The magnetic field promoted the polymerization; the conversion of monomers and the molecular weight of the polymers obtained increased with increasing field strength in the range of 0–0.1 T. The dependence of the composition and tacticity of the mother polymer on the magnitude of the magnetic field was studied. Using graft or block copolymers, which consisted of hard and soft segments, the effect of a magnetic field was further investigated. The degree of hardness and tightness of the hydrophobic areas (reaction areas) formed by the mother polymer in the aqueous solution was found to affect the magnetic field effect on the uncatalyzed polymerization. The overall activation energy obtained in the magnetic field was almost equal to that obtained without a magnetic field. 相似文献
59.
Yew-Hong Ooi Chun-Chieh Han Hong-Cheu Lin Kenji Kubo Masato M. Ito 《Liquid crystals》2013,40(4):516-527
A series of symmetrical trimeric liquid crystalline compounds of which the molecular structure with a central core of 1,3,5-benzene attached by three rod-like mesogenic Schiff base moieties via the propylene spacers and ether linkages has successfully been synthesised and characterised by infra red and nuclear magnetic resonance spectroscopic techniques. All the star-shaped compounds in this series exhibit predominantly SmC phase except the analogue possessing terminal C8H17 group. It is apparent that the members with even parity from C10H21 to C16H33 show enantiotropic SmC phase while the member with longest terminal chain of C18H37 is inclined to monotropic smectogen. The X-ray diffraction measurements reveal that the tilted smectic layer structures of the SmC phase are confirmed to have an obvious sharp peak at small angles of 2θ ~ 1.03°–1.48° with d-spacing values of 4.01–4.58 nm, which are corresponding to tilt angles of ~48° in the SmC phase. 相似文献
60.
Nobutaka Yamaoka Kohei Sumida Itsuki Itani Hiroko Kubo Yusuke Ohnishi Sho Sekiguchi Dr. Toshifumi Dohi Prof. Dr. Yasuyuki Kita 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(44):15004-15011
Metal‐free oxidative C? C coupling by using polyalkoxybenzene‐derived diaryliodonium(III) salts as both the oxidant and aryl source has been developed. These salts can induce single‐electron‐transfer (SET) oxidation to yield electron‐rich arenes and subsequently transfer the polyalkoxyphenyl group into in situ generated aromatic radical cations to produce biaryl products. The reaction is promoted by a Lewis acid that activates the iodonium salts. It has been revealed that the reactivity of the salts under acidic conditions is quite different to their known behavior under basic conditions. The reactivity preference of a series of iodonium salts in the SET oxidation and their ligand transfer abilities have been systematically investigated and the results are summarized in this report. 相似文献