全文获取类型
收费全文 | 348篇 |
免费 | 29篇 |
国内免费 | 1篇 |
专业分类
化学 | 254篇 |
晶体学 | 2篇 |
力学 | 3篇 |
数学 | 18篇 |
物理学 | 101篇 |
出版年
2023年 | 1篇 |
2022年 | 3篇 |
2021年 | 4篇 |
2020年 | 6篇 |
2019年 | 8篇 |
2018年 | 7篇 |
2017年 | 1篇 |
2016年 | 8篇 |
2015年 | 14篇 |
2014年 | 13篇 |
2013年 | 12篇 |
2012年 | 18篇 |
2011年 | 28篇 |
2010年 | 15篇 |
2009年 | 17篇 |
2008年 | 19篇 |
2007年 | 21篇 |
2006年 | 24篇 |
2005年 | 19篇 |
2004年 | 10篇 |
2003年 | 18篇 |
2002年 | 14篇 |
2001年 | 13篇 |
2000年 | 12篇 |
1999年 | 3篇 |
1998年 | 2篇 |
1997年 | 1篇 |
1996年 | 5篇 |
1995年 | 3篇 |
1994年 | 3篇 |
1993年 | 3篇 |
1992年 | 4篇 |
1990年 | 2篇 |
1988年 | 2篇 |
1987年 | 6篇 |
1986年 | 2篇 |
1985年 | 4篇 |
1984年 | 7篇 |
1983年 | 2篇 |
1982年 | 7篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1979年 | 3篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 2篇 |
1975年 | 2篇 |
1974年 | 2篇 |
1973年 | 2篇 |
1970年 | 1篇 |
排序方式: 共有378条查询结果,搜索用时 62 毫秒
131.
Inside Back Cover: Porous Carbon Fibers Containing Pores with Sizes Controlled at the Ångstrom Level by the Cavity Size of Pillar[6]arene (Angew. Chem. Int. Ed. 22/2015)
下载免费PDF全文
![点击此处可从《Angewandte Chemie (International ed. in English)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
132.
Dr. Marian Olaru Dr. Julius F. Kögel Risa Aoki Prof. Dr. Ryota Sakamoto Prof. Dr. Hiroshi Nishihara Dr. Enno Lork Dr. Stefan Mebs Dr. Matthias Vogt Prof. Dr. Jens Beckmann 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(1):275-284
The reaction of 2,6-F2C6H3SiMe3 with Ph2PLi provided 2,6-(Ph2P)2C6H3SiMe3 ( 1 ), which can be regarded as precursor for the novel anionic tridentate ligand [2,6-(Ph2P)2C6H3]− (PCP)−. The reaction of 1 with [AuCl(tht)] (tht=tetrahydrothiophene) afforded 2,6-(Ph2PAuCl)2C6H3SiMe3 ( 2 ). The subsequent reaction of 2 with CsF proceeded with elimination of Me3SiF and yielded the neutral tetranuclear complex linear-[Au4Cl2(PCP)2] ( 3 ) comprising a string-like arrangement of four Au atoms. Upon chloride abstraction from 3 with NaBArF4 (ArF=3,5-(CF3)2C6H3) in the presence of tht, the formation of the dicationic tetranuclear complex linear-[Au4(PCP)2(tht)2](BArF4)2 ( 4 ) was observed, in which the string-like structural motif is retained. Irradiation of 4 with UV light triggered a facile rearrangement in solution giving rise to the dicationic tetranuclear complex cyclo-[Au4(PCP)2(tht)2](BArF4) ( 5 ), which comprises a rhomboidal motif of four Au atoms. In 3 – 5 , the Au atoms are associated by a number of significant aurophilic interactions. The atom-economic and selective reaction of 3 with HgCl2 yielded the neutral trinuclear bimetallic complex [HgAu2Cl3(PCP)] ( 6 ) comprising significant metallophilic interactions between the Au and Hg atoms. Therefore, 6 may be also regarded as a metallopincer complex [ClHg(AuCAu)] between HgII and the anionic tridentate ligand [2,6-(Ph2PAuCl)2C6H3]− (AuCAu)− containing a central carbanionic binding site and two “gold-arms” contributing pincer-type chelation trough metallophilic interactions. Compounds 1 – 6 were characterized experimentally by multinuclear NMR spectroscopy and X-ray crystallography and computationally using a set of real-space bond indicators (RSBIs) derived from electron density (ED) methods including Atoms In Molecules (AIM), the Electron Localizability Indicator (ELI-D) as well as the Non-Covalent Interaction (NCI) Index. 相似文献
133.
β-1,3-Dicarbonyl aldehydes were synthesized by iron-catalyzed oxidative reactions between 1,3-dicarbonyl compounds and two molecules of tertiary amines in the presence of tert-butyl hydroperoxide (TBHP). α,β-Unsaturated aldehydes generated by tertiary amine oxidation in situ act as key intermediates under mild reaction conditions. 相似文献
134.
Kobayashi K Nishimura Y Gao F Gotoh K Nishihara Y Takagi K 《The Journal of organic chemistry》2011,76(6):1949-1952
Carbonylative homocoupling of arylzinc compounds 1 using 1 atm of CO and 1,2-dibromoethane as an oxidant was achieved in the presence of Rh-dppf catalyst, affording symmetrical diaryl ketones in good yields. Under similar conditions, Pd or Ni catalysts induced oxidative homocoupling of 1 to yield biaryls instead. The beneficial catalysis by Rh in the carbonylation was presumed to stem from the facility by which the migration of the aryl ligand to CO at the Rh(3+) intermediate occurred. 相似文献
135.
Kimichi Suzuki Masanori Tachikawa Hiroshi Ogawa Somlak Ittisanronnachai Hirotomo Nishihara Takashi Kyotani Umpei Nagashima 《Theoretical chemistry accounts》2011,130(4-6):1039-1042
To analyze the proton/deuteron (H/D) isotope effect on the stable adsorption sites on zeolite-templated carbon (ZTC), we have performed path integral molecular dynamics simulations including thermal and nuclear quantum effects with the semi-empirical PM3 potential at 300?K. Here, for the adsorption sites of additional proton (H*) and deuteron (D*), we chose different five carbon atoms labeled as ??-, ??1-, ??2-, ??-, and ??-carbons from edge to bottom for inside of buckybowl (C36H12 and C36D12). The stable adsorption sites of D* are observed on all carbon atoms, while those of H* are not observed on ??-carbon atom, but only on ??-, ??1-, ??2-, and ??-carbon atoms. This result is explained by the fact that H* can easily go over the barrier height for hydrogen transferring from ??- to ??2-carbons at 300?K, since the zero-point energy of H* is greater than that of D*. 相似文献
136.
137.
Hasegawa Y Takahashi K Kume S Nishihara H 《Chemical communications (Cambridge, England)》2011,47(24):6846-6848
Iron(II) complexes of Z- and E-2,6-di(1H-pyrazol-1-yl)-4-styrylpyridine (Z-2 and E-2, respectively) exhibited visible light photoisomerization from Z-2 to E-2, both in solution and in solid phases. Z-2 occupied the high-spin state over the full temperature range examined, whereas E-2 displayed a spin crossover phenomenon between 100 K and 300 K. 相似文献
138.
Yasushi Nishihara Eiji Inoue Shintaro Noyori Daisuke Ogawa Yoshiaki Okada Masayuki Iwasaki Kentaro Takagi 《Tetrahedron》2012,68(24):4869-4881
In this paper, we explore the copper/palladium-cocatalyzed cross-coupling reactions of 1-aryl-2-trimethylsilylethynes with aryl iodides, bromides, and chlorides as coupling partners, to furnish unsymmetrically disubstituted ethynes in moderate to excellent yields. Various aryl iodides were subjected to reaction under the optimized conditions with 5 mol % of Pd(PPh3)2 and 50 mol % of CuCl. The steric properties of the aryl iodide proved more influential to the outcome of the cross-coupling reaction than electronic factors. In addition, we succeeded in synthesizing unsymmetrical diarylethynes using two different aryl iodides in one-pot. Furthermore, under the same reaction conditions with 10 mol % of PdCl2, 40 mol % of P(4-FC6H4)3, and 50 mol % of CuCl as catalyst, we succeeded in synthesizing unsymmetrical diarylethynes from various aryl bromides. Finally, we explored reactions with aryl chlorides and duly discovered that unsymmetrical diarylethynes were obtainable in moderate to good yields when 10 mol % of Pd(OAc)2, 10 mol % of (?)-DIOP, and 10 mol % of CuCl were used. These reactions proceed through a direct activation of a carbon–silicon bond in alkynylsilanes by CuCl to generate the corresponding alkynylcopper species via transmetalation from silicon to copper. Mechanistic investigations on the reaction of alkynylsilanes with aryl bromides confirmed that the trimethylsilyl bromide generated in situ retarded both transmetalation steps between CuCl and alkynylsilane, and between palladium(II) species formed by oxidative addition and alkynylcopper species. 相似文献
139.
Abstract The lattice constants of Hf1-xTaxFe2 with C14 structure were measured at room temperature under pressure up to 5 GPa. The magnetic phase diagram obtained as a function of pressure was compared with that obtained as a function of Ta concentration x. It is shown that changes in lattice constants by applying pressure and /or by substituting Ta for Hf affect remarkably the magnetic phase stability, which is consistent qualitatively with a recent theoretical prediction based on the local spin density approximation. 相似文献
140.
M Nishihara 《The Journal of the Operational Research Society》2012,63(1):107-121
We develop a model for determining whether a firm should exercise two real options individually or simultaneously. The simultaneous exercise of both options has synergy of cost savings, while the separate exercise of each option benefits from project flexibility. This trade-off determines the optimal exercise policy. We compare static and dynamic management of multiple real options. A firm under static management determines the type of exercise of real options ex ante; on the other hand, a firm under dynamic management makes the decision at the time of exercise. We show that highly correlated projects increase the option values under both styles of management because a firm is more likely to enjoy the synergy gains of joint investment. We also highlight the advantage of dynamic management over static management for weakly correlated projects. 相似文献