全文获取类型
收费全文 | 593篇 |
免费 | 19篇 |
国内免费 | 9篇 |
专业分类
化学 | 382篇 |
晶体学 | 8篇 |
力学 | 6篇 |
数学 | 73篇 |
物理学 | 152篇 |
出版年
2023年 | 3篇 |
2021年 | 9篇 |
2020年 | 5篇 |
2019年 | 15篇 |
2018年 | 7篇 |
2016年 | 18篇 |
2015年 | 6篇 |
2014年 | 10篇 |
2013年 | 27篇 |
2012年 | 28篇 |
2011年 | 32篇 |
2010年 | 26篇 |
2009年 | 25篇 |
2008年 | 21篇 |
2007年 | 39篇 |
2006年 | 34篇 |
2005年 | 33篇 |
2004年 | 22篇 |
2003年 | 27篇 |
2002年 | 24篇 |
2001年 | 18篇 |
2000年 | 23篇 |
1999年 | 8篇 |
1998年 | 7篇 |
1997年 | 4篇 |
1996年 | 8篇 |
1995年 | 3篇 |
1994年 | 4篇 |
1993年 | 6篇 |
1992年 | 7篇 |
1991年 | 9篇 |
1990年 | 8篇 |
1989年 | 5篇 |
1988年 | 7篇 |
1987年 | 3篇 |
1986年 | 8篇 |
1985年 | 11篇 |
1984年 | 3篇 |
1983年 | 7篇 |
1981年 | 3篇 |
1980年 | 3篇 |
1978年 | 3篇 |
1976年 | 11篇 |
1975年 | 7篇 |
1973年 | 4篇 |
1970年 | 5篇 |
1969年 | 3篇 |
1967年 | 3篇 |
1966年 | 3篇 |
1965年 | 2篇 |
排序方式: 共有621条查询结果,搜索用时 31 毫秒
121.
The behavior ofp-nitrotoluene adsorbed at zeolite/n-heptane interface has been investigated by the electronic spectroscopy under pressure up to 300 MPa. The uv-vis absorption bands of adsorbedp-nitrotoluene were deconvoluted into ones for the species adsorbed on the cation sites, and one for that on the pore wall of zeolite. The peak of adsorbed species on the cation site red-shifted by 20–80 nm from the position of the same species in the liquid phase, and their magnitudes of shift depended on the strength of electric field generated by the cation in zeolites. The peak intensities of adsorbed species on the cation site were enhanced but these or the pore wall site were reduced with the increase in pressure, suggesting that a part ofp-nitroluene molecules on the pore wall site desorbed and the adsorption on the cation site was enhanced by compression. The pressure dependence of peak intensity indicated that the behavior of this adsorption system was strongly governed by the solvation structure of the adsorbate in the zeolite pore. In particular, it was found that the adsorption of solvent molecules on the cation site strongly affected the volume change of the adsorption system. 相似文献
122.
Tohru Ozawa 《Communications in Mathematical Physics》1991,139(3):479-493
We consider the scattering problem for the nonlinear Schrödinger equation in 1+1 dimensions: where = /x,R{0},R,p>3. We show that modified wave operators for (*) exist on a dense set of a neighborhood of zero in the Lebesgue spaceL
2(R) or in the Sobolev spaceH
1(R)., The modified wave operators are introduced in order to control the long range nonlinearity |u|2
u.Laboratoire associé au Centre National de la Recherche Scientifique 相似文献
123.
Ozawa M 《Physical review letters》1991,67(15):1956-1959
124.
We consider the scattering problem for the Hartree type equation in
n
withn2:
相似文献
125.
Strain‐Induced Double Carbon–Carbon Bond Activations of Cycloparaphenylenes by a Platinum Complex: Application to the Synthesis of Cyclic Diketones 下载免费PDF全文
Dr. Eiichi Kayahara Toshiki Hayashi Dr. Katsuhiko Takeuchi Prof. Dr. Fumiyuki Ozawa Keita Ashida Prof. Dr. Sensuke Ogoshi Prof. Dr. Shigeru Yamago 《Angewandte Chemie (International ed. in English)》2018,57(35):11418-11421
The carbon–carbon (C?C) bond activation of [n]cycloparaphenylenes ([n]CPPs) by a transition‐metal complex is herein reported. The Pt0 complex Pt(PPh3)4 regioselectively cleaves two C?C σ bonds of [5] CPP and [6]CPP to give cyclic dinuclear platinum complexes in high yields. Theoretical calculations reveal that the relief of ring strain drives the reaction. The cyclic complex was further transformed into a cyclic diketone by using a CO insertion reaction. 相似文献
126.
Matsuta K. Minamisono T. Tanigaki M. Fukuda M. Nojiri Y. Mihara M. Onishi T. Yamaguchi T. Harada A. Sasaki M. Miyake T. Minamisono K. Fukao T. Sato K. Matsumoto Y. Ohtsubo T. Fukuda S. Momota S. Yoshida K. Ozawa A. Kobayashi T. Tanihata I. Alonso J. R. Krebs G. F. Symons T. J. M. 《Hyperfine Interactions》1996,97(1):519-526
The magnetic moments of the proton drip-line nuclei13O(I
= 3/2–,T
1/2 = 8.6 ms) and 9C(I
= 3/2–,T
1/2 = 126 ms) have been determined for the first time through the combined techniques of polarized radioactive nuclear beams and-NMR detection. The observed magnetic moments are ¦(13O)¦ = 1.3891 ±0.0003
N and ¦(9C)¦ = 1.3914 ±0.0005
N. Spin expectation values are deduced to be 0.76 and 1.44 for13O and9C, respectively. While the of13O is consistent with the systematics from isospinT= 1/2 mirror pairs, the of9C is unusually large, even far larger than the single particle value, = 1. 相似文献
127.
128.
The IR absorption band of methane adsorbed on an active carbon was obtained at 153 K. The IR nu(1) band of methane (inherently IR inactive in the gaseous phase) adsorbed on the active carbon was induced by the electric field of surface groups, even though the adsorbent was known to be macroscopically hydrophobic. The source of the electric field was suggested to be a hydrogen-bonding surface carboxyl or phenolic OH group. The strength of the electric field was estimated to be 1.13 x 10(5) esu, although the number of sites bearing an electric field was very small. A strong electric field (1.75 x 10(5) esu) was created on the carbon surface by oxidation, and its origin was suggested to be carbonyl groups. Copyright 2000 Academic Press. 相似文献
129.
T Miwa S Sakashita H Ozawa J Haginaka N Asakawa Y Miyake 《Journal of chromatography. A》1991,566(1):163-171
An ovomucoid-conjugated polymer column was prepared for the liquid chromatographic resolution of racemic compounds. The column showed strong retention of acidic solutes, a characteristic attributed to the structure of the stationary phase support gel. Although the efficiency of the column was lower than that of an ovomucoid-conjugated silica gel column, enantiospecific chlorprenaline determination in plasma was achieved with solute amounts from 1.0 ng to 0.1 microgram. 相似文献
130.
Cyclodextrin-modified monolithic columns for resolving dansyl amino acid enantiomers and positional isomers by capillary electrochromatography 总被引:1,自引:0,他引:1
We describe beta- and gamma-cyclodextrins (beta- and gamma-CD)-modified monolithic columns prepared by sol-gel process and chemical modifications. The monolithic silica column was fabricated inside a fused-silica capillary with 100 microm inner diameter by sol-gel process. The monolithic silica matrix was chemically modified chiral selectors of beta- or gamma-CDs with a spacer of 3-glycidoxypropyltrimethoxysilane by on-column reactions. Gamma-CD-modified monolithic column has successfully been applied for the separation of dansyl amino acid enantiomers. Beta-CD-modified monolithic column has been used for the separation of the positional isomers of o-, m-, and p-cresols and the enantioseparation of racemates of benzoin and several dansyl amino acids by capillary electrochromatography, respectively. For the separation of neutral positional isomers, a positive electric field was applied. However, for the separation of negatively charged analytes, a negative electric field was applied at the inlet of column. The separation efficiency of 5.0 x 10(4) theoretical plates/m for dansyl-L-threonine was obtained at electric field strength of -300 V/cm in the mobile phase of 50 mM 2-(N-morpholino)ethanesulfonic acid (MES)-Tris/methanol (70/30) buffer at pH 7.0. L-enantiomers were eluted as the first peak. Scanning electron micrograph showed that monolithic columns have the morphology of continuous skeleton and large through-pores. 相似文献
|