全文获取类型
收费全文 | 1118篇 |
免费 | 224篇 |
国内免费 | 16篇 |
专业分类
化学 | 1327篇 |
力学 | 1篇 |
综合类 | 5篇 |
数学 | 3篇 |
物理学 | 22篇 |
出版年
2024年 | 1篇 |
2023年 | 12篇 |
2022年 | 49篇 |
2021年 | 42篇 |
2020年 | 89篇 |
2019年 | 41篇 |
2018年 | 43篇 |
2017年 | 27篇 |
2016年 | 70篇 |
2015年 | 60篇 |
2014年 | 72篇 |
2013年 | 80篇 |
2012年 | 76篇 |
2011年 | 58篇 |
2010年 | 49篇 |
2009年 | 69篇 |
2008年 | 72篇 |
2007年 | 69篇 |
2006年 | 58篇 |
2005年 | 69篇 |
2004年 | 63篇 |
2003年 | 44篇 |
2002年 | 33篇 |
2001年 | 15篇 |
2000年 | 7篇 |
1999年 | 5篇 |
1998年 | 2篇 |
1997年 | 9篇 |
1996年 | 10篇 |
1995年 | 16篇 |
1994年 | 6篇 |
1993年 | 5篇 |
1992年 | 2篇 |
1991年 | 2篇 |
1990年 | 2篇 |
1989年 | 5篇 |
1987年 | 4篇 |
1986年 | 2篇 |
1985年 | 4篇 |
1984年 | 5篇 |
1982年 | 6篇 |
1981年 | 2篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1976年 | 1篇 |
排序方式: 共有1358条查询结果,搜索用时 15 毫秒
101.
102.
103.
104.
105.
Jochen Lutz The Vinh Ho Richard H. Fish Andreas Schmid 《Journal of organometallic chemistry》2004,689(25):4783-4790
The biocatalytic, regioselective hydroxylation of 2-hydroxybiphenyl to the corresponding catechol was accomplished utilizing the monooxygenase 2-hydroxybiphenyl 3-monooxygenase (HbpA). The necessary natural 1,4-dihydronicotinamde adenine dinucleotide (NADH) co-factor for this biocatalytic process was replaced by a biomimetic co-factor, N-benzyl-1,4-dihydronicotinamide, 1b. The interaction between the flavin (FAD) containing HbpA enzyme and the corresponding biomimetic NADH compound, N-benzyl-1,4-dihdronicotinamide, 1b, for hydride transfer, was shown to readily occur. The in situ recycling of the reduced NADH biomimic 1b from 1a was accomplished with [Cp*Rh(bpy)H](Cl); however, productive coupling of this regeneration reaction to the enzymatic hydroxylation reaction was not totally successful, due to a deactivation process concerning the HbpA enzyme peripheral groups; i.e., -SH or -NH2 possibly reacting with the precatalyst, [Cp*Rh(bpy)(H2O)](Cl)2, and thus inhibiting the co-factor regeneration process. The deactivation mechanism was studied, and a promising strategy of derivatizing these peripheral -SH or -NH2 groups with a polymer containing epoxide was successful in circumventing the undesired interaction between HbpA and the precatalyst. This latter strategy allowed tandem co-factor regeneration using 1a or 2a, [Cp*Rh(bpy)(H2O)](Cl)2, and formate ion, in conjunction with the polymer bound, FAD containing HbpA enzyme to provide the catechol product. 相似文献
106.
The molecular-recognition abilities of a water-soluble chitin derivative, chitin-graft-polysarcosine (2) were investigated using chitinase, lysozyme, and wheat germ agglutinin (WGA). The enzymatic degradabilities of 2 were evaluated using chitinase and lysozyme. The molecular weight of those compounds of 2 with a higher affinity toward water decreased rapidly, as compared with partially deacetylated chitin (1). The 1H NMR spectrum of the low-molecular-weight fraction, yielded after lysozymic hydrolysis, indicated that saccharide residues in the chitinous backbone were specifically recognized by the lysozyme, then beta-glycosidic linkages in the backbone were selectively hydrolyzed. Furthermore, the molecular-recognition ability of the chitinous backbone of graft copolymer 2 toward the lectin WGA was elucidated by the enzyme-linked lectin-binding assay (ELLA). It was revealed that the graft copolymer with a lower degree of substitution (DS) value efficiently interacted with WGA. Interestingly, a graft copolymer having longer polysarcosine side chains showed higher recognition ability toward WGA than that having short side chains. 相似文献
107.
108.
109.
110.
Integrated microfluidic systems 总被引:2,自引:0,他引:2
Ismagilov RF 《Angewandte Chemie (International ed. in English)》2003,42(35):4130-4132