全文获取类型
收费全文 | 120篇 |
免费 | 8篇 |
专业分类
化学 | 97篇 |
数学 | 3篇 |
物理学 | 28篇 |
出版年
2023年 | 1篇 |
2022年 | 2篇 |
2020年 | 7篇 |
2019年 | 3篇 |
2018年 | 1篇 |
2017年 | 2篇 |
2016年 | 2篇 |
2015年 | 9篇 |
2014年 | 7篇 |
2013年 | 4篇 |
2012年 | 8篇 |
2011年 | 9篇 |
2010年 | 6篇 |
2009年 | 9篇 |
2008年 | 11篇 |
2007年 | 5篇 |
2006年 | 5篇 |
2005年 | 4篇 |
2004年 | 5篇 |
2003年 | 7篇 |
2002年 | 6篇 |
2001年 | 1篇 |
2000年 | 1篇 |
1997年 | 1篇 |
1995年 | 1篇 |
1994年 | 2篇 |
1988年 | 1篇 |
1985年 | 2篇 |
1984年 | 3篇 |
1983年 | 1篇 |
1982年 | 2篇 |
排序方式: 共有128条查询结果,搜索用时 31 毫秒
101.
Dr. Masaaki Komatsuda Prof. Dr. Junichiro Yamaguchi 《Chemical record (New York, N.Y.)》2023,23(9):e202200281
Fluorine-containing molecules have attracted much attention in medicinal, agrochemical, and materials sciences because they offer unique physical and biological properties. Therefore, many efficient fluorination reactions have been developed over the years. Recent advancements in fluorination chemistry have expanded the range of substrates, and regioselectivity/stereoselectivity control has also been achieved. Ring-opening fluorination is an efficient method to construct complex fluorine-containing molecules with diversity, starting from simple cyclic compounds. This review aims to summarize developments in ring-opening fluorination, particularly with larger-sized cyclic compounds. Fluorine introduction and bond cleavage of cyclic compounds such as carbocycles, heterocycles, and aromatics provide efficient access to fluorine-containing compounds that are difficult to be synthesized by conventional methods. 相似文献
102.
Stereodivergent Synthesis of Arylcyclopropylamines by Sequential CH Borylation and Suzuki–Miyaura Coupling
下载免费PDF全文
![点击此处可从《Angewandte Chemie (International ed. in English)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Shin Miyamura Misaho Araki Prof. Dr. Takayoshi Suzuki Prof. Dr. Junichiro Yamaguchi Prof. Dr. Kenichiro Itami 《Angewandte Chemie (International ed. in English)》2015,54(3):846-851
A step‐economical and stereodivergent synthesis of privileged 2‐arylcyclopropylamines (ACPAs) through a C(sp3)? H borylation and Suzuki–Miyaura coupling sequence has been developed. The iridium‐catalyzed C? H borylation of N‐cyclopropylpivalamide proceeds with cis selectivity. The subsequent B‐cyclopropyl Suzuki–Miyaura coupling catalyzed by [PdCl2(dppf)]/Ag2O proceeds with retention of configuration at the carbon center bearing the Bpin group, while epimerization at the nitrogen‐bound carbon atoms of both the starting materials and products is observed under the reaction conditions. This epimerization is, however, suppressed in the presence of O2. The present new ACPA synthesis results in not only a significant reduction in the steps required for making ACPA derivatives, but also the ability to access either isomer (cis or trans) by simply changing the atmosphere (N2 or O2) in the coupling stage. 相似文献
103.
CH Activation Generates Period‐Shortening Molecules That Target Cryptochrome in the Mammalian Circadian Clock
下载免费PDF全文
![点击此处可从《Angewandte Chemie (International ed. in English)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Tsuyoshi Oshima Dr. Iori Yamanaka Dr. Anupriya Kumar Dr. Junichiro Yamaguchi Dr. Taeko Nishiwaki‐Ohkawa Kei Muto Rika Kawamura Dr. Tsuyoshi Hirota Prof. Dr. Kazuhiro Yagita Prof. Dr. Stephan Irle Prof. Dr. Steve A. Kay Prof. Dr. Takashi Yoshimura Prof. Dr. Kenichiro Itami 《Angewandte Chemie (International ed. in English)》2015,54(24):7193-7197
The synthesis and functional analysis of KL001 derivatives, which are modulators of the mammalian circadian clock, are described. By using cutting‐edge C? H activation chemistry, a focused library of KL001 derivatives was rapidly constructed, which enabled the identification of the critical sites on KL001 derivatives that induce a rhythm‐changing activity along with the components that trigger opposite modes of action. The first period‐shortening molecules that target the cryptochrome (CRY) were thus discovered. Detailed studies on the effects of these compounds on CRY stability implicate the existence of an as yet undiscovered regulatory mechanism. 相似文献
104.
Naohiko OHKOUCHI Junichiro KURODA Asahiko TAIRA 《Proceedings of the Japan Academy. Series B, Physical and biological sciences》2015,91(7):273-291
Black shale is dark-colored, organic-rich sediment, and there have been many episodes of black shale deposition over the history of the Earth. Black shales are source rocks for petroleum and natural gas, and thus are both geologically and economically important. Here, we review our recent progress in understanding of the surface ocean ecosystem during periods of carbonaceous sediment deposition, and the factors triggering black shale deposition. The stable nitrogen isotopic composition of geoporphyrins (geological derivatives of chlorophylls) strongly suggests that N2-fixation was a major process for nourishing the photoautotrophs. A symbiotic association between diatoms and cyanobacteria may have been a major primary producer during episodes of black shale deposition. The timing of black shale formation in the Cretaceous is strongly correlated with the emplacement of large igneous provinces such as the Ontong Java Plateau, suggesting that black shale deposition was ultimately induced by massive volcanic events. However, the process that connects these events remains to be solved. 相似文献
105.
Shin Miyamura Misaho Araki Takayoshi Suzuki Junichiro Yamaguchi Kenichiro Itami 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2015,127(3):860-865
A step‐economical and stereodivergent synthesis of privileged 2‐arylcyclopropylamines (ACPAs) through a C(sp3) H borylation and Suzuki–Miyaura coupling sequence has been developed. The iridium‐catalyzed C H borylation of N‐cyclopropylpivalamide proceeds with cis selectivity. The subsequent B‐cyclopropyl Suzuki–Miyaura coupling catalyzed by [PdCl2(dppf)]/Ag2O proceeds with retention of configuration at the carbon center bearing the Bpin group, while epimerization at the nitrogen‐bound carbon atoms of both the starting materials and products is observed under the reaction conditions. This epimerization is, however, suppressed in the presence of O2. The present new ACPA synthesis results in not only a significant reduction in the steps required for making ACPA derivatives, but also the ability to access either isomer (cis or trans) by simply changing the atmosphere (N2 or O2) in the coupling stage. 相似文献
106.
Ryosuke Takise Kei Muto Prof. Dr. Junichiro Yamaguchi Prof. Dr. Kenichiro Itami 《Angewandte Chemie (International ed. in English)》2014,53(26):6791-6794
The nickel‐catalyzed α‐arylation of ketones with readily available phenol derivatives (esters and carbamates) provides access to useful α‐arylketones. For this transformation, 3,4‐bis(dicyclohexylphosphino)thiophene (dcypt) was identified as a new, enabling, air‐stable ligand for this transformation. The intermediate of an assumed C? O oxidative addition was isolated and characterized by X‐ray crystal‐structure analysis. 相似文献
107.
Aleksandar Staykov Junichiro Yamabe Brian P. Somerday 《International journal of quantum chemistry》2014,114(10):626-635
A small addition of oxygen to hydrogen gas is known to mitigate the hydrogen embrittlement (HE) of steels. As atomic hydrogen dissolution in steels is responsible for embrittlement, catalysis of molecular hydrogen dissociation by the steel surface is an essential step in the embrittlement process. The most probable role of oxygen in mitigating HE is to inhibit the reactions between molecular hydrogen and the steel surface. To elucidate the mechanism of such surface reaction of hydrogen with the steel in the presence of oxygen, hydrogen, and oxygen adsorption, dissociation, and coadsorption on the Fe(100) surface were investigated using density functional theory. The results show that traces of O2 would successfully compete with H2 for surface adsorption sites due to the grater attractive force acting on the O2 molecule compared to H2. The H2 dissociation would be hindered on iron surfaces with predissociated oxygen. Prompted by the notable results for H2 + O2, other practical systems were considered, that is, H2 + CO and CH4. Calculations were performed for the CO chemisorption and H2 dissociation on iron surface with predissociated CO, as well as, CH4 surface dissociation. The results indicate that CO inhibition of H2 dissociation proceeds via similar mechanism to O2 induced inhibition, whereas CH4 traces in the H2 gas have no effect on H2 dissociation. © 2014 Wiley Periodicals, Inc. 相似文献
108.
109.
110.
Marc Steinmetz Kirika Ueda Prof. Dr. Stefan Grimme Dr. Junichiro Yamaguchi Dr. Sylvia Kirchberg Prof. Dr. Kenichiro Itami Prof. Dr. Armido Studer 《化学:亚洲杂志》2012,7(6):1256-1260
Direct C? H phenylation of 2‐ethylthiophene and 2‐chlorothiophene with PhPdI(bipy) complex to form either the corresponding 4‐phenyl or 5‐phenylthiophene derivative is studied under stoichiometric conditions using various Lewis acids as additives. It is shown that reactions occur via the corresponding cationic Pd complex (PhPdbipy+) and that the counteranion determines the regioselectivity. High‐level DFT calculations reveal that C? C bond formation occurs via a carbopalladation pathway and not via electrophilic palladation. These calculations give some indications regarding the regioselectivity of the thiophene arylation. 相似文献