全文获取类型
收费全文 | 891篇 |
免费 | 25篇 |
国内免费 | 3篇 |
专业分类
化学 | 719篇 |
晶体学 | 14篇 |
力学 | 19篇 |
数学 | 47篇 |
物理学 | 120篇 |
出版年
2023年 | 5篇 |
2021年 | 5篇 |
2020年 | 7篇 |
2019年 | 16篇 |
2018年 | 9篇 |
2017年 | 9篇 |
2016年 | 14篇 |
2015年 | 16篇 |
2014年 | 17篇 |
2013年 | 42篇 |
2012年 | 39篇 |
2011年 | 43篇 |
2010年 | 23篇 |
2009年 | 30篇 |
2008年 | 49篇 |
2007年 | 63篇 |
2006年 | 62篇 |
2005年 | 49篇 |
2004年 | 51篇 |
2003年 | 52篇 |
2002年 | 36篇 |
2001年 | 13篇 |
2000年 | 16篇 |
1999年 | 9篇 |
1998年 | 15篇 |
1997年 | 11篇 |
1996年 | 11篇 |
1995年 | 8篇 |
1994年 | 6篇 |
1993年 | 7篇 |
1992年 | 6篇 |
1991年 | 5篇 |
1990年 | 8篇 |
1989年 | 9篇 |
1988年 | 10篇 |
1986年 | 7篇 |
1985年 | 16篇 |
1984年 | 17篇 |
1982年 | 12篇 |
1981年 | 13篇 |
1980年 | 6篇 |
1979年 | 7篇 |
1978年 | 12篇 |
1977年 | 15篇 |
1976年 | 9篇 |
1975年 | 4篇 |
1974年 | 5篇 |
1973年 | 3篇 |
1972年 | 3篇 |
1967年 | 3篇 |
排序方式: 共有919条查询结果,搜索用时 203 毫秒
71.
Front Cover: Construction of a Triangle‐Shaped Trimer and a Tetrahedron Using an α‐Helix‐Inserted Circular Permutant of Cytochrome c555 (Chem. Asian J. 10/2018)
下载免费PDF全文
![点击此处可从《化学:亚洲杂志》网站下载免费的PDF全文](/ch/ext_images/free.gif)
72.
Umakoshi K Yamasaki T Fukuoka A Kawano H Ichikawa M Onishi M 《Inorganic chemistry》2002,41(16):4093-4095
Treatment of pyridine-2-thiol (pytH) with H(2) (60 atm) in the presence of 5-methylpyridine-2-thiolate (5-mpyt)-bridged dinuclear Pt(III), Pt(II), or Pd(II) complexes (1 mol %) in DMF at 150 degrees C for 72 h leads to the formation of pyridine in 3-51% yield. From the (1)H NMR study of the exchange reactions and of the products under D(2) pressure, it is suggested that the catalytic reaction involves bimetallic activation of the pyt ligand followed by the liberation of pyridine and H(2)S. 相似文献
73.
Spectroscopic and crystallographic studies on the stability of self-assembled coordination nanotubes
Aoyagi M Tashiro S Tominaga M Biradha K Fujita M 《Chemical communications (Cambridge, England)》2002,(18):2036-2037
On complexation with (en)Pd(NO3)2, tetrakis(3,5-pyridine) ligand gives two isomeric coordination nanotubes, which are in slow equilibrium despite the presence of sixteen Pd-N bonds in the tube framework. 相似文献
74.
The reaction of 2,3-dichloro-5,6-dicyanopyrazine ( 1 ) with enamines as well as a few tertiary amines as enamine precursors was investigated. Both reactions gave aminovinyl-substituted pyrazine derivatives. During the attempted purification of 3c or 3d by column chromatography on silica gel, 2-chloro-5,6-dicyano-3-(1′-oxocyclopent-2′-yl)pyrazine ( 4 ) was obtained, apparently by hydrolytic cleavage. The products prepared are all of interest as potential pesticides. 相似文献
75.
Minoru Kumakura Masaru Yoshida Isao Kaetsu 《Applied biochemistry and biotechnology》1978,3(3):175-183
The immobilization ofStreptomyces phaeochromogenes cells was studied by the radiation-induced polymerization of various hydrophobic glass-forming monomers at low temperatures. The glucose isomerase activity of cells immobilized in hydrophobic polymers showed no decrease in activity with repeated use (batch enzyme reaction). Activity increased with increasing monomer concentration in contrast to results with the immobilized enzyme. The hydrophobic polymer composite was microspheric in form. The particle diameter of the composite increased with the increasing monomer concentration.K m values of the immobilized cells were close to that of intact cells. It was deduced that the cells were trapped on the surface part of the hydrophobic polymer ready to react with the substrate, and not within the matrix where diffusion would play an important role in reaction rates. 相似文献
76.
The C-S stretching vibrations of 28 aliphatic sulfides including one thiol are summarized, and all of the C-S stretching bands are classified into several groups. An extraordinarily low frequency associated with the ethyl group is discussed briefly. 相似文献
77.
Calorimetric measurements at 25°C were made to determine the thermodynamic quantities for the intercalation of pyridine with α- and γ-zirconium phosphates. These phosphates showed exothermic reactions with ΔH0 = ?59.3 and ?21.9 kJ mole?1, respectively. The large difference between the depyridination temperatures for both intercalates is rediscussed with the aid of the ΔG0 data obtained. 相似文献
78.
79.
4,4'-Dihydroxytriphenylmethanes were synthesized using Br?nsted acid or Lewis acid in yields of 24-86% as target compounds for developing antiviral agents. Most of the 4,4'-dihydroxytriphenylmethanes showed significant activity against herpes simplex virus type 1 (anti-HSV-1 activity) in a plaque reduction assay. Higher cytotoxicity was observed generally in halogenated 4,4'-dihydroxytriphenylmethanes (2a-d) than in non-halogenated derivatives. The non-halogenated derivative, 4,4',4"-trihydroxy-3"-methoxytriphenylmethane (3), showed remarkable antiviral activity with an EC(50) value of 1.8 microg/ml. 相似文献
80.
Ohki Y Sunada Y Honda M Katada M Tatsumi K 《Journal of the American Chemical Society》2003,125(14):4052-4053
The [8Fe-7S] core of the P-clusters in nitrogenases is unique among the known [Fe-S] clusters which are essential to electron-transfer processes in nature. The [8Fe-7S] cluster has been thought unstable and to exist only in protein environments. We found that this unusual [8Fe-7S] structure can be self-assembled from the reaction of Fe(II) bis-amide, tetramethylthiourea, 2,4,6-triisopropylbenzenethiol, and elemental sulfur in a specific mole ratio. The structure of the complex isolated therefrom closely resembles that of the reduced form (PN) of the P-clusters, while the 6Fe(II)2Fe(III) oxidation state was manifested by the M?ssbauer study. 相似文献