全文获取类型
收费全文 | 1615篇 |
免费 | 42篇 |
国内免费 | 7篇 |
专业分类
化学 | 1130篇 |
晶体学 | 18篇 |
力学 | 19篇 |
数学 | 44篇 |
物理学 | 453篇 |
出版年
2023年 | 9篇 |
2022年 | 8篇 |
2021年 | 13篇 |
2020年 | 17篇 |
2019年 | 19篇 |
2018年 | 19篇 |
2016年 | 19篇 |
2015年 | 28篇 |
2014年 | 46篇 |
2013年 | 61篇 |
2012年 | 89篇 |
2011年 | 92篇 |
2010年 | 46篇 |
2009年 | 60篇 |
2008年 | 77篇 |
2007年 | 102篇 |
2006年 | 89篇 |
2005年 | 89篇 |
2004年 | 54篇 |
2003年 | 56篇 |
2002年 | 63篇 |
2001年 | 51篇 |
2000年 | 27篇 |
1999年 | 14篇 |
1998年 | 12篇 |
1997年 | 17篇 |
1996年 | 21篇 |
1995年 | 14篇 |
1994年 | 16篇 |
1993年 | 22篇 |
1992年 | 31篇 |
1991年 | 22篇 |
1990年 | 31篇 |
1989年 | 21篇 |
1988年 | 29篇 |
1987年 | 33篇 |
1986年 | 32篇 |
1985年 | 29篇 |
1984年 | 20篇 |
1983年 | 11篇 |
1982年 | 15篇 |
1981年 | 11篇 |
1980年 | 11篇 |
1979年 | 19篇 |
1978年 | 11篇 |
1977年 | 16篇 |
1975年 | 12篇 |
1974年 | 19篇 |
1973年 | 7篇 |
1971年 | 6篇 |
排序方式: 共有1664条查询结果,搜索用时 0 毫秒
1.
Dr. Nozomi Mihara Dr. Yasuyuki Yamada Dr. Hikaru Takaya Prof. Yasutaka Kitagawa Dr. Kazunobu Igawa Prof. Katsuhiko Tomooka Prof. Hiroshi Fujii Prof. Kentaro Tanaka 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(13):3369-3375
Development of supramolecular methods to further activate a highly reactive intermediate is a fascinating strategy to create novel potent catalysts for activation of inert chemicals. Herein, a supramolecular approach to enhance the oxidizing ability of a high-valent oxo species of a nitrido-bridged iron porphyrinoid dimer that is a known potent molecular catalyst for light alkane oxidation is reported. For this purpose, a nitrido-bridged dinuclear iron complex of porphyrin-phthalocyanine heterodimer 3 5+, which is connected through a fourfold rotaxane, was prepared. Heterodimer 3 5+ catalyzed ethane oxidation in the presence of H2O2 at a relatively low temperature. The site-selective complexation of 3 5+ with an additional anionic porphyrin (TPPS4−) through π–π stacking and electrostatic interactions afforded a stable 1:1 complex. It was demonstrated that the supramolecular post-synthetic modification of 3 5+ enhances its catalytic activity efficiently. Moreover, supramolecular conjugates achieved higher catalytic ethane oxidation activity than nitrido-bridged iron phthalocyanine dimer, which is the most potent iron-oxo-based molecular catalyst for light-alkane oxidation reported so far. Electrochemical measurements proved that the electronic perturbation from TPPS4− to 3 5+ enhanced the catalytic activity. 相似文献
2.
3.
4.
5.
6.
M. Fukushima H. Tamate N. Fujii Y. Nakano 《Journal of Radioanalytical and Nuclear Chemistry》2003,257(1):105-108
In this work, we determined the levels of trace metals in protein fractions isolated from rock oysters by neutron activation analysis (NAA) and particle induced X-ray emission (PIXE). Proteins were extracted from mantles and hepatopancreases of rock oysters and fractionated by size-exclusion high performance liquid chromatography (HPLC). The protein fractions from mantles and hepatopancreases are found to be abundant in Fe, Cu, Zn, Mn, Pb, and Ag. HPLC profiles of Fe, Cu, Zn, and Ag indicate that those elements are bound to proteins extracted from mantles and hepatopancreases. 相似文献
7.
N Fujii T Watanabe A Otaka K Bessho I Yamamoto T Noda H Yajima 《Chemical & pharmaceutical bulletin》1987,35(12):4769-4776
8.
9.
10.
In this paper, we treat a domain optimization problem in which the boundary-value problem is a Neumann problem. In the case where the domain is in a three-dimensional Euclidean space, the first-order and the second-order necessary conditions which the optimal domain must satisfy are derived under a constraint which is the generalization of the requisite of constant volume.Portions of this paper were presented at the 13th IFIP Conference on System Modelling and Optimization, Tokyo, Japan, 1987. 相似文献