全文获取类型
收费全文 | 201篇 |
免费 | 8篇 |
专业分类
化学 | 159篇 |
晶体学 | 4篇 |
力学 | 9篇 |
数学 | 19篇 |
物理学 | 18篇 |
出版年
2023年 | 1篇 |
2022年 | 1篇 |
2021年 | 2篇 |
2020年 | 2篇 |
2019年 | 2篇 |
2018年 | 2篇 |
2017年 | 4篇 |
2016年 | 8篇 |
2015年 | 3篇 |
2014年 | 4篇 |
2013年 | 11篇 |
2012年 | 12篇 |
2011年 | 15篇 |
2010年 | 4篇 |
2009年 | 4篇 |
2008年 | 13篇 |
2007年 | 10篇 |
2006年 | 9篇 |
2005年 | 8篇 |
2004年 | 9篇 |
2003年 | 16篇 |
2002年 | 16篇 |
2001年 | 3篇 |
2000年 | 2篇 |
1998年 | 6篇 |
1997年 | 3篇 |
1996年 | 2篇 |
1995年 | 3篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1990年 | 3篇 |
1989年 | 5篇 |
1988年 | 2篇 |
1986年 | 2篇 |
1985年 | 5篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1975年 | 4篇 |
排序方式: 共有209条查询结果,搜索用时 15 毫秒
201.
Naokazu Kano Kazuhide Yanaizumi Xiangtai Meng Takayuki Kawashima 《Heteroatom Chemistry》2012,23(5):429-434
Phosphine imides with a boryl substituent 3–5 were synthesized. Their structures were revealed to have a tetracoordinated boron and a phosphorus atom, featuring the N–B coordination by X‐ray crystallographic analysis and NMR spectroscopy. The phosphine imide moiety was persistent to hydrolysis, methylation, and the aza‐Wittig reaction. The N–B coordination remained intact upon treating with pyridine or fluoride ion. © 2012 Wiley Periodicals, Inc. Heteroatom Chem 23:429–434, 2012; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.21033 相似文献
202.
Zhenjun Du Toshihiro Kawatani Kazuhide Kataoka Rikiya Omatsu Junzo Nokami 《Tetrahedron》2012,68(11):2471-2480
Isopropyl, ethyl, and methyl 2-(2-benzothiazolylsulfinyl)acetates have been found to be useful synthetic reagents for sulfinyl-Knoevenagel reaction with various aldehydes to give directly the corresponding 4-hydroxyalk-2-enoates [R′CH(OH)CHCHCO2R], which are ubiquitous structures in biologically active natural products and useful building blocks for organic synthesis of chiral compounds. From the optically pure (R)-2-(2-benzothiazolylsulfinyl)acetates (>99% ee) prepared by the enzymatic kinetic resolution of (±)-2-(2-benzothiazolylsulfinyl)acetates, optically active 4-hydroxyalk-2-enoates (up to 91% ee) have been obtained in good yields. 相似文献
203.
204.
Mase N Watanabe K Yoda H Takabe K Tanaka F Barbas CF 《Journal of the American Chemical Society》2006,128(15):4966-4967
We have developed a direct, asymmetric Michael reaction that can be performed in brine or seawater without addition of organic solvents. A bifunctional catalyst with long hydrophobic alkyl chains efficiently catalyzed Michael reactions and afforded the desired products in excellent yield with high enantiomeric excess, even when only an equal molar ratio of the donor to acceptor was used. 相似文献
205.
Tao ZF Konishi K Keith G Hecht SM 《Journal of the American Chemical Society》2006,128(46):14806-14807
The antitumor antibiotic bleomycin has long been believed to exert its therapeutic effects at the level of DNA cleavage. Recently, evidence has been presented to suggest that RNA cleavage may also be important and that one or more transfer RNAs may be involved. To define those tRNAs that may represent important loci for the action of bleomycin, we have fractionated chicken liver tRNAs and identified those isoacceptors most susceptible to oxidative cleavage by Fe(II).BLM. Two chicken liver tRNAs, tRNA3Lys and tRNAPhe, were found to be cleaved with exceptional facility by Fe(II).BLM, and both were cleaved predominantly at U66. The cleavage of tRNA3Lys was shown to be minimally affected by physiological concentrations of Mg2+. Chicken liver tRNA3Lys is identical in sequence with human tRNA3Lys. These findings support a possible role for a critical tRNA such as tRNA3Lys in the mechanism by which bleomycin mediates its antitumor activity. 相似文献
206.
207.
208.
Keisuke Shigenobu Taku Sudoh Junichi Murai Kaoru Dokko Masayoshi Watanabe Kazuhide Ueno 《Chemical record (New York, N.Y.)》2023,23(8):e202200301
Highly concentrated electrolytes (HCEs) have a similarity to ionic liquids (ILs) in high ionic nature, and indeed some of HECs are found to behave like an IL. HCEs have attracted considerable attention as prospective candidates for electrolyte materials in future lithium secondary batteries owing to their favorable properties both in the bulk and at the electrochemical interface. In this study, we highlight the effects of the solvent, counter anion, and diluent of HCEs on the Li+ ion coordination structure and transport properties (e. g., ionic conductivity and apparent Li+ ion transference number measured under anion-blocking conditions, ). Our studies on dynamic ion correlations unveiled the difference in the ion conduction mechanisms in HCEs and their intimate relevance to values. Our systematic analysis of the transport properties of HCEs also suggests the need for a compromise to simultaneously achieve high ionic conductivity and high values. 相似文献
209.
Unique macromolecular helicity inversion of stereoregular, optically active poly(phenylacetylene) derivatives induced by external achiral and chiral stimuli is briefly reviewed. Stereoregular, cis-transoidal poly(phenylacetylene)s bearing an optically active substituent, such as (1R,2S)-norephedrine (poly- 1 ) and β-cyclodextrin residues (poly- 2 ), show an induced circular dichroism (ICD) in the UV-visible region of the polymer backbone in solution due to a predominantly one-handed helical conformation of the polymers. However, poly- 1 undergoes a helix-helix transition upon complexation with chiral acids having an R configuration, and the complexes exhibit a dramatic change in the ICD of poly- 1 . Poly- 2 also shows the inversion of macromolecular helicity responding to molecular and chiral recognition events that occurred at the remote cyclodextrin residues from the polymer backbone; the helicity inversion is accompanied by a visible color change. A similar helix-helix transition of poly((R)- or (S)-(4-((1-(1-naphthyl)ethyl)carbamoyl)phenyl)acetylene) is also briefly described. 相似文献