全文获取类型
收费全文 | 357篇 |
免费 | 9篇 |
国内免费 | 1篇 |
专业分类
化学 | 310篇 |
晶体学 | 1篇 |
力学 | 1篇 |
数学 | 16篇 |
物理学 | 39篇 |
出版年
2023年 | 2篇 |
2022年 | 4篇 |
2021年 | 3篇 |
2020年 | 7篇 |
2019年 | 5篇 |
2018年 | 2篇 |
2017年 | 3篇 |
2016年 | 4篇 |
2015年 | 7篇 |
2014年 | 11篇 |
2013年 | 22篇 |
2012年 | 26篇 |
2011年 | 33篇 |
2010年 | 19篇 |
2009年 | 9篇 |
2008年 | 27篇 |
2007年 | 30篇 |
2006年 | 23篇 |
2005年 | 20篇 |
2004年 | 19篇 |
2003年 | 21篇 |
2002年 | 26篇 |
2001年 | 3篇 |
2000年 | 3篇 |
1999年 | 2篇 |
1998年 | 2篇 |
1997年 | 1篇 |
1996年 | 4篇 |
1995年 | 1篇 |
1994年 | 3篇 |
1992年 | 2篇 |
1991年 | 4篇 |
1990年 | 1篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1935年 | 1篇 |
排序方式: 共有367条查询结果,搜索用时 15 毫秒
71.
Acyclic diterpene glycosides, named capsianosides I', II, III (1), C (2), D (3), E (4) and F (5), have been isolated from the dried hot red pepper fruits of Capsicum annuum L. used in Kimchi. The structures of these compounds have been revised in the sugar connectivities by 1D- and 2D-NMR spectroscopic and chemical methods. 相似文献
72.
Yoshiya T Taniguchi A Sohma Y Fukao F Nakamura S Abe N Ito N Skwarczynski M Kimura T Hayashi Y Kiso Y 《Organic & biomolecular chemistry》2007,5(11):1720-1730
The O-acyl isopeptide method has recently received attention as an efficient synthetic method for peptides. Herein, forty kinds of "O-acyl isodipeptide unit" Boc-Ser/Thr(Fmoc-Xaa)-OH (1-40) were effectively synthesized in two-steps without epimerization. The O-acyl isodipeptide units are important building blocks to enable the routine use of the O-acyl isopeptide method. 相似文献
73.
Tryptophan (Trp), an aromatic amino acid, is a constituent of peptides/proteins and is also a precursor of serotonin, kynurenine derivatives, and nicotinamide adenine dinucleotides. There have been a number of reports on photochemical reactions involving peptides/proteins which contain Trp that showed significant photodegradation, dimerization, and photoionization. The photochemical properties of Trp have not been fully elucidated, and this would provide novel insight into the handling of Trp-containing peptides/proteins. Consequently, we have been trying to evaluate the photochemical properties of Trp, as well as other essential amino acids, focusing on their photosensitivity, photodegradation, and their ability to induce lipid peroxidation. Among all the essential amino acids tested, Trp exhibited the maximal level of superoxide anion generation under 18 h of light exposure (30000 lux). UV spectral analysis of Trp suggested the absorbability of UVA/B light, and exposure of Trp, in both solid and solution states, to UVA/B light resulted in significant photodegradation (t(0.5): 18 h) and gradual color changes. In addition, photoirradiated Trp generated lipoperoxidant, a causative agent of photoirritation, and this might be associated with ROS generation. 相似文献
74.
A twisted link is a generalization of a virtual link, which is related to a link diagram on a closed, possibly non-orientable surface. In this paper we generalize the Miyazawa polynomial invariant of a virtual link to an invariant of a twisted link in two formulae one of which is introduced by A. Ishii and the other by the author. 相似文献
75.
Gakuse Hoshina Shigeru Ohba Naoko Tsuchiya Tetsuhiko Isobe Mamoru Senna 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(5):e191-e192
The title mononuclear iron(II) complex, [Fe(C12H8N2)3](NCS)2·3H2O, has a slightly distorted octahedral coordination. One of the thiocyanate ions and one of the water molecules of crystallization show positional disorder. 相似文献
76.
We introduce a two-variable polynomial invariant of a long virtual knot, which dominates the Kauffman f-polynomial and the Miyazawa polynomial of the closure. Our invariant satisfies a product formula for the concatenation product of long virtual knots. It describes a formula of the Miyazawa polynomial of a ‘connected sum’ of two virtual knots. It also gives lower bounds for the real crossing number and the virtual crossing number of a long virtual knot. 相似文献
77.
In representation theory of finite groups, one of the most important and interesting problems is that, for a p-block A of a finite group G where p is a prime, the numbers k(A) and ℓ(A) of irreducible ordinary and Brauer characters, respectively, of G in A are p-locally determined. We calculate k(A) and ℓ(A) for the cases where A is a full defect p-block of G, namely, a defect group P of A is a Sylow p-subgroup of G and P is a nonabelian metacyclic p-group M
n+1(p) of order p
n+1 and exponent p
n
for
n \geqslant 2{n \geqslant 2}, and where A is not necessarily a full defect p-block but its defect group P = M
n+1(p) is normal in G. The proof is independent of the classification of finite simple groups. 相似文献
78.
79.
We study the nonequilibrium steady state realized in a general stochastic system attached to multiple heat baths. Starting from the detailed fluctuation theorem, we derive concise and suggestive expressions for the corresponding stationary distribution which are correct up to the second order in thermodynamic forces. The probability of a microstate eta is proportional to exp[Phi(eta)] where Phi(eta)=-[under summation operator]kbeta_{k}E_{k}(eta) is the excess entropy change. Here, E_{k}(eta) is the difference between two kinds of conditioned path ensemble averages of excess heat transfer from the kth heat bath whose inverse temperature is beta_{k}. This result can be easily extended to steady states maintained with other sources, e.g., particle current driven by an external force. Our expression may be verified experimentally in nonequilibrium states realized, for example, in mesoscopic systems. 相似文献
80.
Kawasaki T Ogawa A Terashima R Saheki T Ban N Sekiguchi H Sakaguchi KE Sakamoto M 《The Journal of organic chemistry》2005,70(8):2957-2966
Hexahydropyrrolo[2,3-b]indoles 6 were synthesized in five steps from indolin-3-one 8 by a general and efficient method, in which elements of molecular diversity were readily added onto the 3a-position of the pyrrolo[2,3-b]indole ring system. Horner-Wadsworth-Emmons reaction of 2-allyloxyindolin-3-ones 7, derived from indolin-3-one 8 and a variety of allylic alcohols, smoothly proceeded with successive Claisen rearrangement to give the corresponding 3-allyl-3-cyanomethylindolin-2-ones 15. Indolin-2-ones 15 were converted into pyrrolo[2,3-b]indoles 6 using partial hydrolysis followed by reductive cyclization with LiAlH(4). Synthesis of N-methylated pyrrolo[2,3-b]indole derivatives 23 and 26 is also described. 相似文献