全文获取类型
收费全文 | 1762篇 |
免费 | 35篇 |
国内免费 | 5篇 |
专业分类
化学 | 1292篇 |
晶体学 | 14篇 |
力学 | 23篇 |
综合类 | 1篇 |
数学 | 77篇 |
物理学 | 395篇 |
出版年
2021年 | 9篇 |
2020年 | 8篇 |
2019年 | 18篇 |
2018年 | 10篇 |
2017年 | 9篇 |
2016年 | 15篇 |
2015年 | 29篇 |
2014年 | 28篇 |
2013年 | 77篇 |
2012年 | 72篇 |
2011年 | 94篇 |
2010年 | 49篇 |
2009年 | 37篇 |
2008年 | 92篇 |
2007年 | 110篇 |
2006年 | 95篇 |
2005年 | 80篇 |
2004年 | 72篇 |
2003年 | 75篇 |
2002年 | 81篇 |
2001年 | 54篇 |
2000年 | 46篇 |
1999年 | 23篇 |
1998年 | 16篇 |
1997年 | 10篇 |
1996年 | 19篇 |
1995年 | 13篇 |
1994年 | 23篇 |
1993年 | 24篇 |
1992年 | 25篇 |
1991年 | 25篇 |
1990年 | 24篇 |
1989年 | 17篇 |
1988年 | 23篇 |
1987年 | 31篇 |
1986年 | 24篇 |
1985年 | 35篇 |
1984年 | 23篇 |
1983年 | 16篇 |
1982年 | 19篇 |
1981年 | 14篇 |
1980年 | 17篇 |
1979年 | 20篇 |
1978年 | 24篇 |
1977年 | 20篇 |
1976年 | 19篇 |
1975年 | 25篇 |
1974年 | 22篇 |
1973年 | 18篇 |
1972年 | 10篇 |
排序方式: 共有1802条查询结果,搜索用时 15 毫秒
21.
Atsushi Ikeda Masaru Kawaguchi Yoshio Suzuki Tsukasa Hatano Munenori Numata Seiji Shinkai Akio Ohta Makoto Ohta 《Journal of inclusion phenomena and macrocyclic chemistry》2000,38(1-4):163-170
The calixarene-fullerene interaction,which causes only a slight change in the absorptionspectra, has been substantiated by calorimetricmeasurements: the H° values arecomparable with those obtained from the associationconstants estimated by a spectroscopic method. Furthermore, we determined the association constantbetween homooxacalix[3]arene and [60]fullerenederivatives with a porphyrin moiety by fluorescencespectra. 相似文献
22.
Kinetics of chemiluminescence reactions of 2-methyl-6-phenylimidazo[1,2-a]pyrazin-3(7H)-one (1c, Cypridina luciferin analogue) and substituent effects of the 6-aryl group of derivatives 1 strongly suggest that the rate-determining step is a single electron transfer from an anion derived from 1 to a triplet molecular oxygen (O2) in the oxygenation process. 相似文献
23.
[reaction: see text] Several functionalized terminal allenes were prepared in moderate to excellent yield by a palladium-catalyzed reaction of chloroprene (2-chloro-1,3-butadiene) with soft nucleophiles. 相似文献
24.
25.
Satoshi Ikeda 《Annalen der Physik》1987,499(8):558-562
Some structural considerations are made on the Finslerian gravitational field: A Finslerian metrical structure such as gλχ(x, y) = γλχ(x) + hλχ(x, y) is proposed, where γλχ denotes the Riemann metric of Einstein's gravitational field, while hλχ the Finsler metric induced by the Riemann metric hij(y) of the internal field; The intrinsic behaviour of the internal variable y, which is expressed as ?i = K(x, y) yj in the internal field, is grasped by the Finslerian parallelism δyi (=0), which is reflected in the spatial structure of the external gravitational field by the mapping relation δyχ = e(x) δyi. The whole metrical Finsler connection D for gλχ(i.e., Dgλχ = 0) is determined by taking account of the intrinsic behaviour δyχ. 相似文献
26.
The nature of a very high-dimensional chaotic attractor in an infinite-dimensional phase space is examined for the purpose of studying the relationships between the physical processes occurring in the real space and the characteristics of high-dimensional attractor in the phase space. We introduce two complementary bases from which the attractor is observed, one the Lyapunov basis composed of the Lyapunov vectors and the another the Fourier basis composed of the Fourier modes. We introduce the exterior subspaces on the basis of the Lyapunov vectors and observe the chaotic motion projected onto these exteriors. It is shown that a certain statistical property of the projected motion changes markedly as the exterior subspace goes out of the attractor. The origin of such a phenomenon is attributed to more fundamental features of our attractor, which become manifest when the attractor is observed from the Lyapunov basis. A counterpart of the phenomenon can be observed also on the Fourier basis because there is a statistical one-to-one correspondence between the Lyapunov vectors and the Fourier modes. In particular, a statistical property of the high-pass filtered time series reflects clearly the difference between the interior and the exterior of the attractor. 相似文献
27.
Satoshi Ito Kazuya Koizumi Katsuhiko Fukuda Naohiro Kameta Tsukasa Ikeda Toru Oba Kazuhisa Hiratani 《Tetrahedron letters》2006,47(48):8563-8566
A new series of BINOL-based macrocycles with two phenolic protons have been synthesized via oxidative coupling reaction using CuCl(OH)-TMEDA. 相似文献
28.
[structure: see text] New fluorescent compounds (1), lariat ethers having plural pyrenylmethyl groups on the sidearms, were prepared, and their complexation behavior with alkaline earth metal cations was examined by fluorescence spectrometry. The pyrene excimer emission decreased accompanied with an increase in the monomer emission upon complexation with the metal ion. This finding is ascribed to the cooperative participation of one of the two sidearms in the complexation of the crown ring with the metal ion. 相似文献
29.
Akiya Karen Noriaki Ikeda Noboru Mataga Fumio Tanaka† 《Photochemistry and photobiology》1983,37(5):495-502
Formation of singlet charge transfer (heteroexcimer) states in the course of the fluorescence quenching of lumiflavin and riboflavin tetrabutyrate by indole and N-methylindole have been directly observed by means of time-resolved absorption spectral measurements using a picosecond laser photolysis method. Similar transient spectra have been observed also in the case of a flavoenzyme, D-amino acid oxidase. 相似文献
30.
[reaction: see text] A conjugated pi-electron compound, 2-aryl-3-silyl-1,3-butadiene, was easily prepared from 1-benzyloxy-3-silyl-2-propyne, bis(iodozincio)methane, and an aryl halide in the presence of nickel catalyst. A subsequent cross-coupling reaction of the product with another aryl halide gave an unsymmetrical 2,3-diaryl-1,3-butadiene efficiently. 相似文献