全文获取类型
收费全文 | 817篇 |
免费 | 26篇 |
国内免费 | 4篇 |
专业分类
化学 | 534篇 |
晶体学 | 3篇 |
力学 | 13篇 |
数学 | 67篇 |
物理学 | 230篇 |
出版年
2023年 | 5篇 |
2022年 | 6篇 |
2021年 | 6篇 |
2020年 | 19篇 |
2019年 | 10篇 |
2018年 | 11篇 |
2017年 | 13篇 |
2016年 | 22篇 |
2015年 | 10篇 |
2014年 | 19篇 |
2013年 | 42篇 |
2012年 | 38篇 |
2011年 | 33篇 |
2010年 | 29篇 |
2009年 | 23篇 |
2008年 | 50篇 |
2007年 | 55篇 |
2006年 | 44篇 |
2005年 | 34篇 |
2004年 | 51篇 |
2003年 | 22篇 |
2002年 | 26篇 |
2001年 | 28篇 |
2000年 | 27篇 |
1999年 | 22篇 |
1998年 | 13篇 |
1997年 | 12篇 |
1996年 | 14篇 |
1995年 | 7篇 |
1994年 | 8篇 |
1993年 | 10篇 |
1992年 | 5篇 |
1991年 | 6篇 |
1990年 | 6篇 |
1989年 | 7篇 |
1988年 | 5篇 |
1987年 | 11篇 |
1986年 | 9篇 |
1985年 | 15篇 |
1984年 | 10篇 |
1983年 | 7篇 |
1982年 | 9篇 |
1981年 | 4篇 |
1980年 | 6篇 |
1979年 | 7篇 |
1978年 | 3篇 |
1977年 | 7篇 |
1976年 | 5篇 |
1975年 | 3篇 |
1973年 | 3篇 |
排序方式: 共有847条查询结果,搜索用时 15 毫秒
11.
Ramesh P Okazaki T Taniguchi R Kimura J Sugai T Sato K Ozeki Y Shinohara H 《The journal of physical chemistry. B》2005,109(3):1141-1147
Double-wall carbon nanotubes (DWNTs) have been selectively synthesized over Fe/Co loaded mesoporous silica by catalytic chemical vapor deposition of alcohol. Several silica materials with desired pore diameter and morphology have been investigated for the DWNT growth. The diameter distribution and selectivity of the DWNT are found to depend on the reaction temperature, pore size, and thermal stability of the support material. A high-yield synthesis of DWNTs has been achieved at 900 degrees C over high-temperature stable mesoporous silica. The outer diameter of DWNTs is found to be in the range of 1.5-5.4 nm with a "d" spacing of 0.38 +/- 0.02 nm between inner and outer layers, which is much larger than those of multiwall carbon nanotubes. 相似文献
12.
Oxime-based salen-type tetradentate ligands with high stability against imine metathesis reaction 总被引:2,自引:0,他引:2
Akine S Taniguchi T Dong W Masubuchi S Nabeshima T 《The Journal of organic chemistry》2005,70(5):1704-1711
Although salen and its analogues are versatile chelate ligands in inorganic and organometallic chemistry, synthesis of unsymmetrical salen derivatives consisting of two different salicylideneimine moieties is difficult because of the C=N bond recombination. To develop stable analogues of salen-type ligands, we synthesized a series of new ligands salamo (=1,2-bis(salicylideneaminooxy)ethane) on the basis of O-alkyl oxime instead of the imine moiety. Eight salamo ligands 1a-h were prepared in 64-88% yields as colorless crystals from the corresponding salicylaldehydes 2a-h. The crystal structure of 1a-c suggests that the oxime-OH form is more predominant than the keto-NH form. The reaction of 2a-e with excess 1,2-bis(aminooxy)ethane gave monooximes 3a-e in 59-86%, which further reacted with a different salicylaldehyde to afford unsymmetrical salamo ligands 4-8 as stable crystals in 51-70%. No reaction took place when a mixture of salamo derivatives 1a and 1b was treated at 40 degrees C in H2O/MeCN (5:95). However, the metathesis reaction of salen derivatives 9a and 9b completed in 2 h to give a statistical mixture. Monooxime 3b was much more stable than monoimine 11 which is difficult to be isolated. These results indicate the extremely high stability of the salamo derivatives 1 and precursors 3. 相似文献
13.
Stable chlorins bearing few or no substituents have been subjected to a variety of reactions including demetalation, magnesium insertion, oxochlorin formation, and bromination followed by Suzuki coupling. The kinetics of deuteration also have been determined for two oxochlorins and a series of chlorins bearing 0, 1, 2, or 3 meso-aryl substituents. 相似文献
14.
K. Okano A. Taniguchi S. Yamada T. Sharshar M. Shibata K. Yamauchi 《Zeitschrift für Physik A Hadrons and Nuclei》1995,352(3):243-244
The -decay of150La, the heaviest isotope of lanthanum, has been identified by observing -rays from mass separated activities obtained at KUR-ISOL. From the decay curves of 97.0 and 208.7 keV -rays in150Ce and of Ce-K X-ray, the half-life of150La has been determined as 0.51(3) s. This value is in agreement with theoretical predictions from microscopic theory. 相似文献
15.
16.
17.
Leesajakul W Nakano M Taniguchi A Handa T 《Colloids and surfaces. B, Biointerfaces》2004,34(4):253-258
Cubosomes are novel dispersed nanoparticles with bicontinuous cubic phases of monoolein in their interior. We investigated their disintegration process in plasma by in vitro and in vivo studies. Cubosomes were incubated with whole plasma or plasma components such as HDL, LDL, and albumin. The lypolysis study indicated lipolytic activity of whole plasma towards cubosomes. Gel filtration chromatography revealed that HDL, LDL and albumin interacted with cubosomes. HDL affected cubosomes’ integrity and gave rise to smaller particles which contained the components of both cubosomes and HDL. Upon incubation with LDL, cubosomes fused with LDL. Albumin was shown to take up monoolein out of the particles. Cubosomes were disintegrated by whole plasma as a result of the interaction with plasma components. It was concluded that in vivo observation of a long circulation time of a hydrophobic substance in cubosomes was due to the sustained behavior of cubosome remnant particles. 相似文献
18.
Five routes to stable chlorins bearing 0 or 1 meso substituents have been investigated, among which reaction of a 9-bromo-1-formyldipyrromethane and 2,3,4,5-tetrahydro-1,3,3-trimethyldipyrrin proved most effective. Application of this route afforded metallochlorins [Cu(II), Zn(II), and Pd(II)] including the chlorin lacking any β-pyrrole and meso substituents. 相似文献
19.
Takaki K Itono Y Nagafuji A Naito Y Shishido T Takehira K Makioka Y Taniguchi Y Fujiwara Y 《The Journal of organic chemistry》2000,65(2):475-481
Three-component coupling of acylphosphonates and two carbonyl compounds leading to beta-hydroxyphosphonates has been achieved with low-valent samariums. Thus, acylphosphonates reacted with aldehydes in the presence of semicatalytic amounts of samarium metal or SmI(2) to give acyloxyphosphonates in good yields. The second coupling reaction of the acyloxyphosphonates with aldehydes or ketones promoted by SmI(2) afforded beta-hydroxyphosphonates instead of olefins. Moreover, these two reactions could be carried out in one pot. 相似文献
20.
Ishikawa Y Matsumoto Y Nishida Y Taniguchi S Watanabe J 《Journal of the American Chemical Society》2003,125(21):6558-6562
Silicon carbide (SiC) and diamond were decomposed to CO(2)(g) by the photocatalysis with TiO(2) at room temperature, although the decomposition rate of diamond was very slow. According to the XPS spectra of Si2p on the SiC surface, SiO(2) was simultaneously formed on the surface by the TiO(2) photocatalysis. The thickness of the SiO(2) formed on the SiC surface during the photocatalytic oxidation for 1 h was estimated to be about 40 A from the depth profile of the XPS spectra using Ar etching. The SiC surface was oxidized by the TiO(2) photocatalysis even under the condition without a direct contact with the TiO(2). This indicates that the photocatalytic oxidation of the SiC occurs due to active oxygen species photogenerated on the TiO(2) surface, but not by hole produced in the valence band of the TiO(2). Moreover, a remote surface treatment system using the quartz beads coated with TiO(2) was developed for the SiC surface oxidation. Consequently, the TiO(2) photocatalysis will be very useful for the surface treatment of SiC such as photopatterning without defects and damage to the substrate because the photocatalytic reaction is carried out under mild conditions. 相似文献