全文获取类型
收费全文 | 306篇 |
免费 | 9篇 |
国内免费 | 2篇 |
专业分类
化学 | 228篇 |
晶体学 | 8篇 |
力学 | 2篇 |
数学 | 27篇 |
物理学 | 52篇 |
出版年
2023年 | 3篇 |
2022年 | 2篇 |
2021年 | 6篇 |
2020年 | 12篇 |
2019年 | 9篇 |
2018年 | 3篇 |
2017年 | 5篇 |
2016年 | 4篇 |
2015年 | 6篇 |
2014年 | 5篇 |
2013年 | 24篇 |
2012年 | 15篇 |
2011年 | 15篇 |
2010年 | 8篇 |
2009年 | 14篇 |
2008年 | 17篇 |
2007年 | 29篇 |
2006年 | 27篇 |
2005年 | 29篇 |
2004年 | 8篇 |
2003年 | 13篇 |
2002年 | 14篇 |
2001年 | 3篇 |
2000年 | 1篇 |
1999年 | 1篇 |
1997年 | 3篇 |
1996年 | 4篇 |
1995年 | 4篇 |
1994年 | 3篇 |
1993年 | 4篇 |
1992年 | 4篇 |
1991年 | 2篇 |
1988年 | 2篇 |
1984年 | 3篇 |
1983年 | 1篇 |
1982年 | 3篇 |
1981年 | 3篇 |
1980年 | 3篇 |
1979年 | 2篇 |
1976年 | 2篇 |
1973年 | 1篇 |
排序方式: 共有317条查询结果,搜索用时 31 毫秒
71.
Yuka Akimura Toshiki Maruyama Naotaka Yoshinaga Satoshi Chiba 《Acta Physica Hungarica A》2006,27(2-3):355-358
We study the hadron-quark phase transition in a molecular dynamics (MD) of quark degrees of freedom. The hadron state at low density and temperature, and the deconfined quark state at high density and temperature are observed in our model. We investigate the equations of state and draw the phase diagram at wide baryon density and temperature range. We also discuss the transport property, e.g. viscosity, of $q\bar q$ matter. It is found that the ratio of the shear viscosity to the entropy density is less than one for quark matter. 相似文献
72.
Sato Y Ichihashi T Nishizawa S Teramae N 《Angewandte Chemie (International ed. in English)》2012,51(26):6369-6372
Firmly tied: The binding affinity of amiloride for an abasic (AP) site-containing RNA duplex is two orders of magnitude superior to the affinity of the corresponding AP site-containing DNA duplex. The observed high binding affinity for the RNA duplex arises from a favorable enthalpy gain. The binding-induced fluorescence response of amiloride is applicable to microRNA detection. 相似文献
73.
Haruka Egawa OoyamaAkiko Hayashi Toshiki MamuraTakashi Ide Toshihiko HinoTakuya Tanigami Katsuhira Yoshida 《Journal of photochemistry and photobiology. A, Chemistry》2012,230(1):38-46
Structural isomers of unsymmetric polycyclicphenazine-type D-π-A fluorescent dyes have been newly synthesized and characterized in both solution and polymer films. The dyes exhibited two strong absorption bands at around 328-401 nm and 516-532 nm, and an intense fluorescence band at around 595-629 nm (Φ = 0.32-0.84) in 1,4-dioxane. The dye-doped polymer films showed good ability of wavelength conversion; the films can efficiently convert ultraviolet and green-yellow lights into red light (Φ = 0.43-0.86). Moreover, the photostability of the dyes-doped PS, PMMA, and PLA films has been investigated. 相似文献
74.
Toshiki Miyazaki Hyun-Min Kim Tadashi Kokubo Hirofumi Kato Takashi Nakamura 《Journal of Sol-Gel Science and Technology》2001,21(1-2):83-88
Untreated tantalum metal forms bonelike apatite layer on its surface in a simulated body fluid (SBF) after a long period. The apatite formation on the tantalum metal is significantly accelerated, when the metal was previously subjected to NaOH and heat treatments to form an amorphous sodium tantalate on its surface. The fast formation of the apatite on the NaOH- and heat-treated tantalum metal was explained as follows. The sodium tantalate on the surface of the metal releases the Na+ ion via exchange with H3O+ ion in SBF to form a lot of Ta-OH groups on its surface. Thus formed Ta-OH groups induce the apatite nucleation and the released Na+ ion accelerates the apatite nucleation by increasing ionic activity product of the apatite in SBF due to increase in OH– ion concentration. In the present study, in order to confirm this explanation, apatite formations on sodium tantalate gels with different Na/Ta atomic ratios, which were prepared by a sol-gel method were investigated. It was found that even Na2O-free tantalum oxide gel forms the apatite on its surface in SBF. This proves that the Ta-OH groups abundant on the gel can induce the apatite nucleation. The apatite-forming ability of the gels increased with increasing Na/Ta atomic ratios of the gels. The sodium-containing tantalum oxide gels released the Na+ ion, the amount of which increased with increasing Na/Ta atomic ratios of the gels. The released Na+ ion gave an increase in pH of SBF. These results prove that the apatite nucleation induced by the Ta-OH groups is accelerated with the released Na+ ion by increasing ionic activity product of the apatite in SBF. 相似文献
75.
Shigeyuki Tasaka Hirokazu Tanabe Yoshiyuki Sasaki Toshiki Machida Mayumi Iino Akira Kiue Seiji Naito Michihiko Kuwano 《Journal of heterocyclic chemistry》1997,34(6):1763-1767
We have investigated 3-substituted-2-phenylimidazo[2,1-b]benzothiazole derivatives and herein we have discussed their pharmaceutical activities. We found that some 2-phenyl-5,6,7,8-tetrahydroimidazo[2,1-b]-benzothiazoles could overcome multidrug resistance for tumor cells. Among them, 2-phenyl-3-(N-methyl-3-piperidyl)carbonylammomiinomemyl-5,6,7,8-tetrahydVoimidazo[2,1-b]benzothiazole [N276-12] demonstrated the most potent activity for overcoming multidrug resistance. 相似文献
76.
Pham Huu Anh Ngoc Toshiki Naito 《Journal of Mathematical Analysis and Applications》2007,328(1):170-191
In this paper, we present a unifying approach to the problems of computing of stability radii of positive linear systems. First, we study stability radii of linear time-invariant parameter-varying differential systems. A formula for the complex stability radius under multi perturbations is given. Then, under hypotheses of positivity of the system matrices, we prove that the complex, real and positive stability radii of the system under multi perturbations (or affine perturbations) coincide and they are computed via simple formulae. As applications, we consider problems of computing of (strong) stability radii of linear time-invariant time-delay differential systems and computing of stability radii of positive linear functional differential equations under multi perturbations and affine perturbations. We show that for a class of positive linear time-delay differential systems, the stability radii of the system under multi perturbations (or affine perturbations) are equal to the strong stability radii. Next, we prove that the stability radii of a positive linear functional differential equation under multi perturbations (or affine perturbations) are equal to those of the associated linear time-invariant parameter-varying differential system. In particular, we get back some explicit formulas for these stability radii which are given recently in [P.H.A. Ngoc, Strong stability radii of positive linear time-delay systems, Internat. J. Robust Nonlinear Control 15 (2005) 459-472; P.H.A. Ngoc, N.K. Son, Stability radii of positive linear functional differential equations under multi perturbations, SIAM J. Control Optim. 43 (2005) 2278-2295]. Finally, we give two examples to illustrate the obtained results. 相似文献
77.
Toshiki Aoki Tomoyuki Fukuda Ken-ichi Shinohara Takashi Kaneko Masahiro Teraguchi Masayuki Yagi 《Journal of polymer science. Part A, Polymer chemistry》2004,42(18):4502-4517
To develop better polymeric materials for optical-resolution membranes, we synthesized nine chiral phenylacetylenes containing pinanyl groups. We used them to investigate the effects of chemical structures, including the number and position of the chiral groups in the monomers, on the induction of chirality in the main chain during polymerization and on the degree of enantioselectivity in the permeation of the polymeric membranes. The monomers included six new chiral p-(oligomethylpinanylsiloxanyl)phenylacetylenes. The homopolymerizations of these nine monomers with a Rh complex produced high-molecular-weight polymers (molecular weight = 105–106). Of the five polymers with a chiral pinanyl group at the 1-position of each oligosiloxanyl group, all except for two polymers showed high molar ellipticity in the main-chain region in the circular dichroism spectra. This finding indicated that these polymers had a chiral helical main chain. The membranes fabricated from all the polymers synthesized in this study were high-quality, except for two polymers. All these membranes showed enantioselective permeabilities for two amino acids and an alcohol. The membranes from the polymers with a chiral helical backbone, a high content of pinanyl groups, no oligodimethylsiloxane moieties, or a combination of these showed good enantioselectivities (= 1.7–640) in permeation. We propose that the sense of the main-chain helicity determined the selectivity. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4502–4517, 2004 相似文献
78.
Masahide Monde Tsuyoshi Uematsu Toshiki Toda Kazuhiko Ohnuma Yoshizumi Yasuda 《Optical Review》1995,2(2):132-134
To make holograms from computer graphic (CG) in a short time, a new holographic three dimensional (3D) printer is proposed here. This printer consists of galvanometer scanners, a micro computer and a laser, and uses a holographic contact duplicating method. Experiments have shown that a hologram of 39 × 41 mm can be obtained in 4 min.Presented at the International Commission for Optics Topical Meeting, Kyoto, 1994. 相似文献
79.
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
![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)
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
80.
Nishino T Okada M Kuroki T Watanabe T Nishiyama Y Sonoda N 《The Journal of organic chemistry》2002,67(24):8696-8698
A convenient synthetic method of unsymmetrical selenides has been developed. When diphenyl diselenide was allowed to react with two equimolar amounts of primary alkyl iodides and bromides in the presence of an equimolar amount of lanthanum metal, alkyl phenyl selenides were formed in moderate to good yields. For the reaction of primary alkyl chlorides and secondary alkyl iodides, the yields of the selenides were low; however, the yields were dramatically improved by the addition of TMEDA or HMPA. A reaction pathway involving the generation of a lanthanum phenylselenolate intermediate was suggested. 相似文献