全文获取类型
收费全文 | 595篇 |
免费 | 12篇 |
国内免费 | 3篇 |
专业分类
化学 | 453篇 |
晶体学 | 3篇 |
力学 | 20篇 |
数学 | 37篇 |
物理学 | 97篇 |
出版年
2022年 | 5篇 |
2021年 | 6篇 |
2020年 | 5篇 |
2019年 | 4篇 |
2018年 | 5篇 |
2017年 | 6篇 |
2016年 | 8篇 |
2015年 | 10篇 |
2014年 | 6篇 |
2013年 | 17篇 |
2012年 | 33篇 |
2011年 | 39篇 |
2010年 | 18篇 |
2009年 | 21篇 |
2008年 | 21篇 |
2007年 | 34篇 |
2006年 | 29篇 |
2005年 | 29篇 |
2004年 | 25篇 |
2003年 | 26篇 |
2002年 | 15篇 |
2001年 | 10篇 |
2000年 | 17篇 |
1999年 | 16篇 |
1998年 | 7篇 |
1997年 | 17篇 |
1996年 | 9篇 |
1995年 | 8篇 |
1994年 | 12篇 |
1993年 | 12篇 |
1992年 | 9篇 |
1991年 | 13篇 |
1990年 | 9篇 |
1989年 | 6篇 |
1988年 | 4篇 |
1987年 | 7篇 |
1986年 | 3篇 |
1985年 | 8篇 |
1984年 | 9篇 |
1983年 | 4篇 |
1982年 | 7篇 |
1981年 | 6篇 |
1980年 | 4篇 |
1979年 | 12篇 |
1978年 | 7篇 |
1977年 | 6篇 |
1976年 | 3篇 |
1974年 | 4篇 |
1973年 | 5篇 |
1972年 | 3篇 |
排序方式: 共有610条查询结果,搜索用时 31 毫秒
1.
Takumi Watanabe Yuichiro Nishizawa Haruka Minato Dr. Chihong Song Prof. Dr. Kazuyoshi Murata Prof. Dr. Daisuke Suzuki 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(23):8934-8938
The three-dimensional structure of nanocomposite microgels was precisely determined by cryo-electron micrography. Several nanocomposite microgels that differ with respect to their nanocomposite structure, which were obtained from seeded emulsion polymerization in the presence of microgels, were used as model nanocomposite materials for cryo-electron micrography. The obtained three-dimensional segmentation images of these nanocomposite microgels provide important insights into the interactions between the hydrophobic monomers and the microgels, that is, hydrophobic styrene monomers recognize molecular-scale differences in polarity within the microgels during the emulsion polymerization. This result led to the formation of unprecedented multi-layered nanocomposite microgels, which promise substantial potential in colloidal applications. 相似文献
2.
3.
Photochemical deprotection of nitro-substituted benzenesulfenates via photoinduced electron transfer
Kan Wakamatsu Mitsuru Kouda Kazuyoshi Shimaoka Haruo Yamada 《Tetrahedron letters》2004,45(34):6395-6398
The photochemical deprotection of alkyl 2,4-dinitrobenzenesulfenate or alkyl 2-nitrobenzenesulfenate was successfully achieved by addition of triethylamine, while it was unsuccessful without triethylamine. The sulfur-oxygen bond cleavage is thought to occur heterolytically in the sulfenate anion radical produced by photoinduced electron transfer with triethylamine. 相似文献
4.
H. -L. Li Y. Ujihira S. Tanaka T. Yamashita K. Horie 《Journal of Radioanalytical and Nuclear Chemistry》1996,210(2):543-553
Positron annihilation lifetime measurements of PMMA, PEMA, PiPMA, PnPMA and PnBMA were performed in the temperature range between 15 and 300 K, where , and relaxational transitions occur for these polyalkylmethacrylates. The variations of free volume size and content calculated from the longest lifetime component against temperature are correlated to the results obtained by dielectric, viscoelastic and dynamic mechanical relaxation data of the polymers. The variations of free volume sizes and contents, apparent free volume fraction and size distribution of the polyalkylmethacrylates are well correlated with the rotational transitions of side chains. The location of free volumes, in which positronium annihilates can be estimated near the vicinity of alkyl groups bound to oxygen atom of side ester chains. 相似文献
5.
Antiviral activity of natural occurring flavonoids in vitro 总被引:2,自引:0,他引:2
Y Tsuchiya M Shimizu Y Hiyama K Itoh Y Hashimoto M Nakayama T Horie N Morita 《Chemical & pharmaceutical bulletin》1985,33(9):3881-3886
6.
Analysis of tea components by high-performance liquid chromatography and high-performance capillary electrophoresis 总被引:3,自引:0,他引:3
Tea is one of the most popular beverages in the world. The number of reports on the analysis of tea components, especially for catechins, has recently been increasing. We review the recent reports on the analysis of tea components using the analytical methods of high-performance liquid chromatography and high-performance capillary electrophoresis. 相似文献
7.
M Horie K Saito Y Hoshino N Nose N Hamada H Nakazawa 《Journal of chromatography. A》1990,502(2):371-378
A simple and selective method for the determination of sulphamethazine (SMT) and its metabolite, N4-acetylsulphamethazine (N4-AcSMT), in meat by high-performance liquid chromatography (HPLC) with photodiode-array detection was developed. The drugs were extracted from meat with 0.2% metaphosphoric acid-methanol (6:4), followed by a Bond-Elut C18 clean-up procedure. The HPLC separation was carried out on a Supersphere RP-18e column (125 X 4.0 mm I.D.) using 0.05 M sodium dihydrogenphosphate (pH 4.5)-acetonitrile (8:2) as the mobile phase at a flow-rate of 0.5 ml/min, and monitored with a photodiode-array detector. The recoveries of SMT and N4-AcSMT from meat fortified at 0.5 micrograms/g were 90.1-93.3 and 93.0-94.4%, respectively, with coefficients of variation of 1.9-3.2 and 1.5-2.7%. The limits of detection were 0.02 micrograms/g for each drug. SMT was found in ten samples of imported meat (12.5%) at levels ranging from 0.05 to 1.05 micrograms/g. 相似文献
8.
Shibuya H Kitamura C Maehara S Nagahata M Winarno H Simanjuntak P Kim HS Wataya Y Ohashi K 《Chemical & pharmaceutical bulletin》2003,51(1):71-74
The microbial transformation of four Cinchona alkaloids (quinine, quinidine, cinchonidine, and cinchonine) by endophytic fungi isolated from Cinchona pubescens was investigated. The endophytic filamentous fungus Xylaria sp. was found to transform the Cinchona alkaloids into their 1-N-oxide derivatives. 相似文献
9.
Konda-Yamada Y Asano K Satou T Monma S Sakayanagi M Satou N Takeda K Harigaya Y 《Chemical & pharmaceutical bulletin》2005,53(5):529-536
Oxopropyl E-(pyrrolidine-2-ylidene)glycinamide (5c) and allyl E-(pyrrolidine-2-ylidene)glycinate (5d) were effectively synthesized from 2,3,5-tri-O-benzyl-4-O-tert-butyldimethylsilyl(TBDMS)-D-arabinal (7) using intramolecular 1,3-dipolar cyclic reaction of azide and olefin as a key reaction. These results proved this cyclic reaction should be applicable for the synthesis of various (pyrrolidine-2-ylidene)glycinate and glycinamide. In addition, the development of a synthetic route for the precursor of an unsaturated cyclic dehydro amino acid involved in azinomycins (carzinophilin) using relating glycinate, methyl E-(pyrrolidine-2-ylidene)glycinate (5a) was described. 相似文献
10.
Yan Ouyang Wei Zhang Yue Ma Na Xu Dai-Zheng Liao Kazuyoshi Yoshimura Shi-Ping Yan 《Structural chemistry》2007,18(6):891-898
Two new tetranuclear complexes of macrocyclic oxamide [Cd(CuL)3](NO3)2·2.5H2O 1, [Mn(CuL)3(OH)2](ClO4)2·Mn(H2O)6·4.5H2O 2 (L = 1,4,8,11-tatraazacyclotradecanne-2,3-dione) have been synthesized, structurally characterized and preliminary investigated
by magnetic studies. The structures of the title complexes consist of a tetranuclear units MCu3 (M = Cd, Mn), the packing diagram shows two-dimensional and three-dimensional system through intermolecular weak interactions.
The temperature-dependent magnetic susceptibilities of complex 2 were analyzed by an approximate treatment leading to J = −33 cm−1, gCu = 2.10, gMn = 1.95 indicating antiferromagnetic exchange between Cu(II) and Mn(II) ions. 相似文献