全文获取类型
收费全文 | 170篇 |
免费 | 9篇 |
国内免费 | 1篇 |
专业分类
化学 | 160篇 |
晶体学 | 1篇 |
数学 | 2篇 |
物理学 | 17篇 |
出版年
2023年 | 2篇 |
2022年 | 3篇 |
2021年 | 3篇 |
2020年 | 8篇 |
2019年 | 5篇 |
2018年 | 1篇 |
2017年 | 2篇 |
2016年 | 5篇 |
2015年 | 6篇 |
2014年 | 7篇 |
2013年 | 7篇 |
2012年 | 12篇 |
2011年 | 18篇 |
2010年 | 7篇 |
2009年 | 7篇 |
2008年 | 12篇 |
2007年 | 16篇 |
2006年 | 12篇 |
2005年 | 13篇 |
2004年 | 8篇 |
2003年 | 5篇 |
2002年 | 7篇 |
2001年 | 4篇 |
1997年 | 3篇 |
1995年 | 1篇 |
1994年 | 2篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1988年 | 1篇 |
1980年 | 1篇 |
排序方式: 共有180条查询结果,搜索用时 0 毫秒
71.
Tsunehisa Hirashita Ayumi Hayashi Makoto Tsuji Jiro Tanaka Shuki Araki 《Tetrahedron》2008,64(11):2642-2650
Intra- and intermolecular reactions of carbon-centered radicals generated by photolysis of organoindium compounds were examined. The photolysis of vinylindium compounds and indium acetylides provided vinyl and alkynyl radicals, respectively, which were trapped with ethyl iodoacetate giving the corresponding β,γ-unsaturated esters. Allylic indium compounds, prepared from 8-bromo- or 8-iodooct-1,6-dienes and powdered indium metal, underwent an intramolecular radical cyclization to afford the 5-exo-trig product. 相似文献
72.
Maki Komiya Miki Kato Daisuke Tadaki Teng Ma Hideaki Yamamoto Ryugo Tero Yuzuru Tozawa Michio Niwano Ayumi Hirano‐Iwata 《Chemical record (New York, N.Y.)》2020,20(7):730-742
An artificial cell membrane that is composed of bilayer lipid membranes (BLMs) with transmembrane proteins incorporated within them represents a well‐defined system for the analysis of membrane proteins, especially ion channel proteins that are major targets for drug design. Because the BLM system has a high compatibility with recently developed cell‐free expression systems, it has attracted attention as a next‐generation drug screening system. However, three issues associated with BLM systems, i. e., their instability, the need for non‐volatile organic solvents and a low efficiency of ion channel incorporation, have limited their use as a drug screening platform. In this personal account, we discuss our recent approaches to address these issues based on microfabrication. We also discuss the potential for using the BLM system combined with cell‐free expression systems as a drug screening system for future personalized medicine. 相似文献
73.
Moriwaki H Watanabe A Arakawa R Tsujimoto Y Shimizu M Noda T Warashina M Tanaka M 《Journal of mass spectrometry : JMS》2002,37(11):1152-1157
We describe a novel method for the determination of three kinds of dimethylbenzylmercapturic acids (DMM) and six kinds of dimethylhippuric acids (DMH), found in urine as metabolites of trimethylbenzenes, based on liquid chromatography/electrospray ionization tandem mass spectrometry. A solid-phase extraction procedure was used for the extractions of DMM and DMH from a urine sample, and the separation was performed on a reversed-phase C(30) column. The analytes were ionized by electrospray in the positive-ion mode. Operating in the multiple reaction monitoring mode, the linearity of the relative mass spectrometric responses to the internal standard versus analyte concentrations were established in the range 0.1-100 ng ml(-1). The extraction procedure was rapid and the relative standard deviations were below 5%. The detection limits of DMM and DMH in the urine by the proposed method were in the ranges 0.26-0.41 and 0.42-2.0 ng l(-1), respectively. Furthermore, DMM and DMH were detected in a urine sample from an individual who did not suffer from occupational exposure to trimethylbenzenes, by using this method. 相似文献
74.
Elucidation of Pseurotin Biosynthetic Pathway Points to Trans‐Acting C‐Methyltransferase: Generation of Chemical Diversity 下载免费PDF全文
Dr. Yuta Tsunematsu Manami Fukutomi Dr. Takayoshi Saruwatari Prof. Dr. Hiroshi Noguchi Prof. Dr. Kinya Hotta Prof. Dr. Yi Tang Prof. Dr. Kenji Watanabe 《Angewandte Chemie (International ed. in English)》2014,53(32):8475-8479
Pseurotins comprise a family of structurally related Aspergillal natural products having interesting bioactivity. However, little is known about the biosynthetic steps involved in the formation of their complex chemical features. Systematic deletion of the pseurotin biosynthetic genes in A. fumigatus and in vivo and in vitro characterization of the tailoring enzymes to determine the biosynthetic intermediates, and the gene products responsible for the formation of each intermediate, are described. Thus, the main biosynthetic steps leading to the formation of pseurotin A from the predominant precursor, azaspirene, were elucidated. The study revealed the combinatorial nature of the biosynthesis of the pseurotin family of compounds and the intermediates. Most interestingly, we report the first identification of an epoxidase C‐methyltransferase bifunctional fusion protein PsoF which appears to methylate the nascent polyketide backbone carbon atom in trans. 相似文献
75.
Masahito Sano Ayumi Kamino Junko Okamura Seiji Shinkai 《Journal of inclusion phenomena and macrocyclic chemistry》2001,41(1-4):49-52
As-grown, string-shaped single-walled carbon nanotubes were transformed into other shapes by applications of organic chemistry. Cutting carbon nanotubes in strong acids affords oxygen-containing groups at both ends of the open tubes. These groups were utilized for ring-closure reactions in very dilute conditions. Atomic force microscopy reveals ring-shaped nanotubes with a mean diameter of 540 nm as products. Also, the end groups were used to react with the surface amine groups of PAMAM dendrimer. It gave star-shaped structures in which straight nanotubes are radiating from dendrimer centers. These experiments clearly demonstrate that covalent chemistry is useful for construction of super-structured carbon nanotubes. 相似文献
76.
77.
78.
Ayumi Hirano-Iwata Michio Niwano Masao Sugawara 《Trends in analytical chemistry : TRAC》2008,27(6):512-520
We describe the current status of techniques for preparing planar lipid bilayers, the fusion of sensory elements and the design of bilayer interfaces for analytical applications. Advances in bilayer fabrication have allowed preparation of lipid bilayers with membrane resistance of >1 GΩ (“gigaseal”) in flow, microfluidic and array formats, which have enabled single-channel and multi-channel recording. Not only biological but also engineered channels have been adopted as sensory elements for lipid-bilayer-based biosensors. Synthetic and inorganic channels are also emerging for designing membranes for lipid-bilayer sensors. We discuss the potential of lipid bilayers containing biological, engineered or synthetic channels for the design of biosensors, including drug-screening biosensors. 相似文献
79.
Variation in the chromatographic,material, and chemical characteristics of methacrylate‐based polymer monoliths during photoinitiated low‐temperature polymerization 下载免费PDF全文
Ayumi Kobayashi Takuya Nakaza Tomohiko Hirano Shinya Kitagawa Hajime Ohtani 《Journal of separation science》2016,39(13):2459-2465
Both the separation behavior and the structure of a polymer monolith column depends on both the reaction solution composition and the polymerization conditions. In photoinitiated low‐temperature polymerization, polymerization temperature, irradiation intensity, and polymerization time were key factors to control the monolith characteristics. In this study, the effect of polymerization time on the chromatographic, material, and chemical characteristics of poly(butyl methacrylate‐co‐ethylene dimethacrylate) monoliths was studied using pyrolysis‐gas chromatography, Raman spectroscopy, inverse size exclusion chromatography, scanning electron microscopy, and chromatographic methods. Both butyl methacrylate and ethylene dimethacrylate monomers were incorporated into the monolith as the polymerization time increased, and it resulted in increases in both the flow resistance (decrease in both permeability and total/through pore porosities) and retention factors. The longer polymerization time led to lower relative amounts of free methacrylate functional groups in the monolith, i.e. cross‐linking was enhanced. The increase of the polymerization time from 8 to 12 min significantly reduced the separation efficiency for the retained analyte, whereas an increase in the fraction of the mesoporosity was observed. 相似文献
80.
Kitano H Gemmei-Ide M Anraku Y Saruwatari Y 《Colloids and surfaces. B, Biointerfaces》2007,56(1-2):188-Optics
A disulfide-carrying random telomer with pendent d-glucosylurea groups (Cys-poly(glucosylureaethyl methacrylate-r-ureaethyl methacrylate), Cys-Poly(GUMA-r-UMA)) was obtained by UV-irradiation of GUMA and UMA in the presence of benzyl N,N-diethyldithiocarbamoyl (BDC) derivative which shows the abilities of initiation, transfer, and termination (iniferter). The disulfide-carrying telomer was accumulated on a gold electrode and colloidal gold-immobilized glass substrate, and the binding of various proteins to the surface of the polymer brush was examined by both cyclic voltammetry (CV) with hydroquinone as a probe, and localized surface plasmon resonance (LSPR) absorption method. The Cys-Poly(GUMA-r-UMA) brush did not show a significant non-specific adsorption of proteins such as bovine serum albumin and egg white lysozyme. Furthermore, sugar binding proteins, concanavalin A (with an affinity for mannose and glucose) and wheat germ agglutinin (with an affinity for N-acetylglucosamine), were only slightly adsorbed to the GUMA-carrying brush, which is in contrast with the prompt and distinct binding of these proteins to the brushes composed of 2-methacryloyloxyethyl d-glucopyranoside and 1-(6′-methacrylamido)hexyl-2-N-acetoamido-2-deoxy-d-glucopyranoside, respectively. The glucosylurea group-carrying telomer brush prepared here might be useful to provide a “bio-inert” surface in bio-medical fields. 相似文献