全文获取类型
收费全文 | 200篇 |
免费 | 2篇 |
专业分类
化学 | 168篇 |
晶体学 | 3篇 |
数学 | 9篇 |
物理学 | 22篇 |
出版年
2023年 | 1篇 |
2022年 | 1篇 |
2021年 | 4篇 |
2020年 | 2篇 |
2019年 | 1篇 |
2018年 | 1篇 |
2016年 | 1篇 |
2015年 | 1篇 |
2014年 | 11篇 |
2013年 | 16篇 |
2012年 | 8篇 |
2011年 | 17篇 |
2010年 | 6篇 |
2009年 | 4篇 |
2008年 | 14篇 |
2007年 | 10篇 |
2006年 | 12篇 |
2005年 | 20篇 |
2004年 | 9篇 |
2003年 | 12篇 |
2002年 | 15篇 |
2001年 | 2篇 |
2000年 | 2篇 |
1999年 | 4篇 |
1998年 | 2篇 |
1997年 | 3篇 |
1996年 | 1篇 |
1994年 | 1篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1987年 | 3篇 |
1985年 | 2篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1973年 | 2篇 |
1968年 | 1篇 |
1964年 | 1篇 |
1962年 | 1篇 |
排序方式: 共有202条查询结果,搜索用时 608 毫秒
101.
We report the development of a new selective and specific electrochemical biosensor for bacterial lipolysaccharide (LPS). An electrode interface was constructed using a l-cysteine-gold nanoparticle (AuNpCys) composite to be immobilized by electrostatic interaction in the network of a poly(vinyl chloride-vinyl acetate maleic acid) (PVM) layer on a gold bare electrode. The impedimetric biosensor is fabricated by self-assembled CramoLL lectin on the PVM-AuNpCys-modified gold electrode through electrostatic interaction. CramoLL is used as the recognition interface. AFM images showed that LPS was specifically recognized on the PVM-AuNpCys-CramoLL system surface. The measurements of cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) showed that the electrochemical response of a redox probe system (K(4)[Fe(CN)(6)](4-)/K(3)[Fe(CN)(6)](3-)) were blocked, due to the procedures of modified electrode with PVM-AuNpCys-CramoLL. In the majority of the experiments the lectin retained its activity as observed through its interaction with LPS from Escherichia coli, Serratia marcescens, Salmonella enterica and Klebsiella pneumoniae. The results are expressed in terms of the charge transfer resistance and current peak anodic using the EIS and CV techniques for the development of a biosensor for contamination by endotoxins. A new type of sensor for selective discrimination of LPS types with a high sensitivity has been obtained. 相似文献
102.
Conversion of the formyl group at the 7-position in chlorophyll (Chl) b to the methyl group via the hydroxymethyl group is biologically important in Chl b degradation. To clarify the effects of the 7-substituents on demetalation properties of chlorophyllous pigments in the early process of Chl b degradation, we report demetalation kinetics of the zinc Chl derivative possessing a 7-hydroxymethyl group, which is a good model compound of the intermediate molecule in the early process of Chl b degradation, under acidic conditions, and compare its properties with those of zinc Chl derivatives possessing a methyl and a formyl group, which are model compounds of Chls a and b, respectively. Demetalation rate constants of 7-hydroxymethyl zinc chlorin were much larger than those of 7-formyl zinc chlorin, but were slightly smaller than those of 7-methyl zinc chlorin. The activation energy for demetalation reaction of 7-formyl zinc chlorin was larger than those of other derivatives. Demetalation rate constants of 7-deformyl-7-hydroxymethyl Chl b were also larger than those of Chl b, and were similar to those of Chl a. These indicate that the 7-hydroxymethyl group in the chlorin macrocycle has a smaller effect on demetalation compared with the 7-formyl group. 相似文献
103.
Noriyuki Isobe Da-Sol Lee Ye-Jin Kwon Satoshi Kimura Shigenori Kuga Masahisa Wada Ung-Jin Kim 《Cellulose (London, England)》2011,18(5):1251-1256
A technique of immobilizing an enzyme/antibody was developed using cellulose hydrogel prepared from an aqueous alkali-urea
solvent. Partial oxidation by sodium periodate activated the cellulose gel for introducing aldehyde groups. Proteins were
covalently introduced to cellulose gel by a Schiff base formation between the aldehyde and the amino groups of proteins, and
stabilized by a reduction of imines. Coloring reactions confirmed the high activity of the immobilized enzymes. The activity
of the immobilized enzymes increased with aldehyde content, but the effect leveled off at a low degree of oxidation, at approximately
8.1 of oxidized glucose/100 glucose unit. The amount of immobilized peroxidase calculated from the activity was 8.0 ng/g for
an aldehyde content of 0.18 mmol/g: 14.6 ng/g for both 0.46 mmol/g and 1.04 mmol/g. The same method could be applied to the
peroxidase antibody. Thus, various active proteins could be immobilized on cellulose gels by mild and facile processing. Owing
to high mechanical and chemical stability of cellulose, this technique and resulting materials are potentially useful in biochemical
processing and sensing technologies. 相似文献
104.
Katsumi Yoshino Yoshiaki Kawagishi Shigenori Satoh Sergey Lee Keizo Nakayama Hiroyoshi Take 《Molecular Crystals and Liquid Crystals》2013,570(2):485-490
Abstract Nano-scale periodic structures of conducting polymer and carbons, which were prepared by infiltration of polymers and carbons in nano-scale interconnected periodic pores in synthetic opals made of regular array of SiO2 spheres and then removing SiO2 by etching, have been found to exhibit novel electrical and optical properties. Their electrical and optical properties in thus fabricated conducting polymer and carbon replicas change drastically upon pyrolysis due to progress of carbonization and graphitization. That is, due to the changes in periodicity, pore size, carbonization degree and crystal structure, electrical conductivity, magnetoconductance and their temperature dependences and optical reflection spectra have changed drastically. These replicas with porous nature can be infiltrated and also intercalated with various materials, resulting in also remarkable changes of properties. The synthetic opal infiltrated with conducting polymer can be electrochemically doped, with which remarkable change of optical properties have been observed due to the shift of the diffraction peak accompanying with the change in refractive index. Alkali metal intercalated carbon and graphite with nano-scale periodic structures have been also studied. The applications of these nano-scale periodic structures of conducting polymer and carbon are also discussed. 相似文献
105.
Fujikawa S Takaki R Kunitake T 《Langmuir : the ACS journal of surfaces and colloids》2006,22(21):9057-9061
We report herein fabrication of arrays of sub-20-nm silica walls via photolithography and the surface sol-gel process. A photolithographically fabricated line template on a silicon wafer was coated with a silica nanolayer using the surface sol-gel process, and then the topmost portion of the silica layer and the template were successively removed using CHF(3) and oxygen plasma, respectively, leaving the sidewalls of the silica layers remaining on the substrate. These walls were fully self-supporting, and the thicknesses of silica wall were 6, 8, and 12 nm at 20, 30, and 60 cycles, respectively. The height/width ratio of the wall was 38 at the 30-cycle coating. This ratio is surprisingly high when compared to that of the conventional photolithography processes. Successive formation of the silica, polymer, and silica layers yielded a trilayer sidewall, and the spacer polymer layer could be selectively removed to form a doubled sidewall. Size reduction and proliferation of sub-20-nm silica wall was thus achieved. The reported method is simple and cost-efficient and opens a gateway to further miniaturization of nanostructures. 相似文献
106.
KENJI FUJIWARA 《Natural Resource Modeling》2010,23(4):591-609
Abstract This paper develops a reciprocal market model of international duopoly with transboundary pollution from consumption to examine the effects of bilateral tariff reductions on the equilibrium pollution tax and welfare. I show that tariff reductions induce each country to raise an emission tax and that trade liberalization is welfare improving if the parameter of pollution damages is sufficiently large. These results are in contrast to the case of production‐generated pollution, and I seek the reason for this contrast. 相似文献
107.
Kohei Shimamura Fuyuki Shimojo Aiichiro Nakano Shigenori Tanaka 《Journal of computational chemistry》2019,40(2):349-359
Recent experiments concerning prebiotic materials syntheses suggest that the iron-bearing meteorite impacts on ocean during Late Heavy Bombardment provided abundant organic compounds associated with biomolecules such as amino acids and nucleobases. However, the molecular mechanism of a series of chemical reactions to produce such compounds is not well understood. In this study, we simulate the shock compression state of a meteorite impact for a model system composed of CO2, H2O, and metallic iron slab by ab initio molecular dynamics combined with multiscale shock technique, and clarify possible elementary reaction processes up to production of organic compounds. The reactions included not only pathways similar to the Fischer–Tropsch process known as an important hydrocarbon synthesis in many planetary processes but also those resulting in production of a carboxylic acid. It is also found that bicarbonate ions formed from CO2 and H2O participated in some forms in most of these observed elementary reaction processes. These findings would deepen the understanding of the full range of chemical reactions that could occur in the meteorite impact events. © 2018 Wiley Periodicals, Inc. 相似文献
108.
109.
110.