全文获取类型
收费全文 | 296篇 |
免费 | 18篇 |
国内免费 | 1篇 |
专业分类
化学 | 241篇 |
晶体学 | 4篇 |
力学 | 5篇 |
数学 | 17篇 |
物理学 | 48篇 |
出版年
2023年 | 3篇 |
2022年 | 2篇 |
2021年 | 7篇 |
2020年 | 7篇 |
2019年 | 10篇 |
2018年 | 2篇 |
2016年 | 9篇 |
2015年 | 8篇 |
2014年 | 5篇 |
2013年 | 12篇 |
2012年 | 13篇 |
2011年 | 23篇 |
2010年 | 12篇 |
2009年 | 5篇 |
2008年 | 11篇 |
2007年 | 19篇 |
2006年 | 35篇 |
2005年 | 16篇 |
2004年 | 24篇 |
2003年 | 18篇 |
2002年 | 13篇 |
2001年 | 6篇 |
1999年 | 2篇 |
1998年 | 4篇 |
1997年 | 4篇 |
1996年 | 2篇 |
1995年 | 2篇 |
1994年 | 1篇 |
1993年 | 3篇 |
1992年 | 2篇 |
1990年 | 2篇 |
1988年 | 4篇 |
1986年 | 2篇 |
1985年 | 5篇 |
1984年 | 5篇 |
1983年 | 4篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1980年 | 1篇 |
1978年 | 4篇 |
1977年 | 3篇 |
1976年 | 1篇 |
1967年 | 1篇 |
排序方式: 共有315条查询结果,搜索用时 234 毫秒
311.
312.
The V(acac)3 (acac = acetylacetonato)/AlEt2Cl catalyst is known to promote the living polymerization of propylene at low temperature. In the present study, the catalyst was modified by contacting with α,ω-unconjugated diene compounds, and the resulting catalyst was applied to propylene polymerization. The polymer produced shows a bimodal molar mass distribution, where the molecular weight of the higher molecular weight portion is twice that of the lower molecular weight portion. By using the CO quenching technique, it was found that the polymer with the higher molecular weight has a telechelic structure. 相似文献
313.
Dr. Yoshifumi Hashikawa Shumpei Sadai Shu Okamoto Prof. Dr. Yasujiro Murata 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2023,135(2):e202215380
Though [60]fullerene is an achiral molecular nanocarbon with Ih symmetry, it could attain an inherent chirality depending upon a functionalization pattern. The conventional chiral induction of C60 relies mainly upon a multiple addition affording a mixture of achiral and chiral isomers while their chiral function would be largely offset by the existence of pseudo-mirror plane(s). These are major obstacles to proceed further study on fullerene chirality and yet leave its understanding elusive. Herein, we showcase a carbene-mediated synthesis of C1-symmetric chiral open [60]fullerenes showing an intense far-red to near-infrared absorption. The large dissymmetry factor of |gabs|=0.12 was achieved at λ=820 nm for circular dichroism in benzonitrile. This is, in general, unachievable by other small chiral organic molecules, demonstrating the potential usage of open [60]fullerenes as novel types of chiral chromophores. 相似文献
314.
To check the possibility of living polymerization with a biscyclopentadienyl metallocene, propylene polymerization was conducted by Cp2ZrMe2 at –78°C or Cp2HfMe2 at –50°C using B(C6F5)3 and AlOct3 as a cocatalyst. The polymer yield increased linearly with polymerization time. The polypropylene obtained showed narrow molecular weight distribution (Mw/Mn 1.04–1.15). In addition, the number-average molecular weight increased in proportion to the polymerization time. It was, thus, found that living polymerization of propylene proceeds with the catalyst systems at a very low temperature. Isospecific living polymerization of 1-hexene also proceeded with the rac-(et)Ind2ZrMe2 catalyst at –78°C. 相似文献
315.
Alberto F. Garrido-Castro Yuta Hioki Yoshifumi Kusumoto Kyohei Hayashi Jeremy Griffin Kaid C. Harper Yu Kawamata Phil S. Baran 《Angewandte Chemie (International ed. in English)》2023,62(42):e202309157
A mild, scalable (kg) metal-free electrochemical decarboxylation of alkyl carboxylic acids to olefins is disclosed. Numerous applications are presented wherein this transformation can simplify alkene synthesis and provide alternative synthetic access to valuable olefins from simple carboxylic acid feedstocks. This robust method relies on alternating polarity to maintain the quality of the electrode surface and local pH, providing a deeper understanding of the Hofer-Moest process with unprecedented chemoselectivity. 相似文献