全文获取类型
收费全文 | 270篇 |
免费 | 4篇 |
国内免费 | 2篇 |
专业分类
化学 | 259篇 |
晶体学 | 7篇 |
物理学 | 10篇 |
出版年
2018年 | 3篇 |
2017年 | 2篇 |
2016年 | 3篇 |
2015年 | 2篇 |
2014年 | 6篇 |
2013年 | 12篇 |
2012年 | 6篇 |
2011年 | 8篇 |
2010年 | 4篇 |
2009年 | 2篇 |
2008年 | 4篇 |
2007年 | 10篇 |
2006年 | 5篇 |
2005年 | 12篇 |
2004年 | 5篇 |
2003年 | 5篇 |
2002年 | 4篇 |
2001年 | 2篇 |
2000年 | 7篇 |
1999年 | 6篇 |
1997年 | 2篇 |
1996年 | 2篇 |
1995年 | 5篇 |
1994年 | 8篇 |
1993年 | 9篇 |
1992年 | 3篇 |
1991年 | 5篇 |
1990年 | 7篇 |
1989年 | 5篇 |
1988年 | 4篇 |
1987年 | 8篇 |
1986年 | 15篇 |
1985年 | 5篇 |
1984年 | 4篇 |
1982年 | 4篇 |
1981年 | 2篇 |
1980年 | 3篇 |
1979年 | 8篇 |
1978年 | 15篇 |
1977年 | 9篇 |
1976年 | 4篇 |
1975年 | 2篇 |
1974年 | 6篇 |
1972年 | 2篇 |
1971年 | 3篇 |
1970年 | 3篇 |
1969年 | 2篇 |
1968年 | 5篇 |
1967年 | 10篇 |
1966年 | 2篇 |
排序方式: 共有276条查询结果,搜索用时 15 毫秒
71.
Bouzid Menaa Masahide Takahashi Yomei Tokuda Toshinobu Yoko 《Journal of Sol-Gel Science and Technology》2006,39(2):185-194
Phenylsilsesquioxane-diphenylsiloxane glass thick films doped with anthracene were prepared from homogeneous coating sols
obtained from two different approaches. One approach consisted in incorporating the dye during the glass preparation (which
implies the incorporation of the dye in an aqueous media). The doped-glass was further dissolved in the solvents mixture composed
of cyclohexane and acetone. The other approach which is non-aqueous consisted simply in dissolving directly the preformed
non-doped polyphenylsiloxane glass in the dye solutions. The stability of the organic-inorganic hybrid glass matrix in most
organic solvents makes possible the incorporation of the dye without problems of miscibility and dispersion in the hybrid
matrix. The coating was performed at room temperature using spin-coating technique prior to further heat-treatment. Crack-free
and homogeneous films of high optical quality were obtained. The optical properties of the doped films based on their absorption
and emission spectra were discussed owing the incorporation route of the dye. The results showed that the non-aqueous approach
used to incorporate the dye minimizes the dye aggregation. This property associated to the preparation route permits to obtain
optically active hybrid films loaded with high concentrations of anthracene (in the order of 10−2 M) which enhance the fluorescence of the doped films. The hybrid doped-films obtained represent therefore a tremendous potential
for applications in the field of optics and photonics including the development of new nonlinear optical materials.
Bouzid Menaa and Masahide Takahashi both the author contributed equally. 相似文献
72.
Photoconductivity of localized electrons, which are not solvated, in γ-irradiated ethanol glass at 4 K was studied. Photocurrents of 10?13 A or larger were stably detected in the wavelength range of 900–2200 nm. The wavelength dependence of the photocurrent reveals that pre-solvated electrons probably have no bound excited states. 相似文献
73.
Silylallenes () are selectively prepared from trimethylsilylpropargyl phenyl ether and trialkylboranes by treatment with sodium methoxide. 相似文献
74.
T. Higashimura Y. Ohsumi K. Kuroda S. Okamura 《Journal of polymer science. Part A, Polymer chemistry》1967,5(4):863-875
Highly crystalline poly(methyl vinyl ether) (PMVE) was produced in toluene in a temperature range of 0 to ?20°C. with the use of sulfuric acid–aluminum sulfate complex (SA catalyst). It was found from the NMR spectra that these polymers contained more than 50% of the triad isotactic fraction and the melting point of the unfractionated polymer was about 130°C. However, PMVE containing a large amount of the isotactic fraction was insoluble in nitromethane, so the triad tacticity of highly crystalline PMVE could not be quantitatively determined. The molecular weight of PMVE increased with increasing conversion and increasing polymerization temperature. This behavior is different from that in metal halide catalysts. Also, the stereoregularity of PMVE decreased with increasing monomer concentration. However, addition of a polar solvent and increasing the polymerization temperature had little effect on the stereoregularity of the polymer. The increase in the isotactic fraction at high catalyst concentration and the difference in the monomer composition in the copolymerization of methyl vinyl ether with 2-chloroethyl vinyl ether by SA catalyst from that obtained by BF3·O(C2H5)2 suggest that the absorption of MVE on a catalyst surface is an important step in the propagation step by SA catalyst. The fraction of the triad tacticity calculated from the enantiomorphic catalyst sites model8 coincided with the experimental results. This fact shows that the steric structure of the adding monomer is determined only by the nature of the catalyst irrespective of the nature of a growing chain end. It is concluded, on considering also the results of the previous paper, that completely different factors can control the steric structure of a polymer even for the same monomer when different catalysts are used. 相似文献
75.
Masahide Takahashi Masaru Suzuki Yuya Miyagawa Rie Ihara Yomei Tokuda Toshinobu Yoko Takashi Nemoto Seiji Isoda 《Journal of Sol-Gel Science and Technology》2010,54(3):319-324
Photo-curable vinyl modified silicate-phosphate alternating copolymers were prepared by a direct condensation of organochlorosilane
and organophosphoric acid in a solvent-free condition. The obtained copolymers have complete alternating copolymer structure
of silicate and phosphate unit, where the main oxo chain consist of –(Si–O–P–O)
n
-network. They exhibited an excellent solubility of ionic species such as ionic organic dyes. It was also demonstrated the
photo-reduction of Au+ ions to form Au nano particles for plasmonics applications. Micro patterns were also fabricated by soft lithographic processes.
These results indicate that the photo-curable alternating copolymers are one of promising materials for advanced optical information
processing devices. 相似文献
76.
Wataru Uchida Maiki Yoshikawa Tomohiro Seki Ryotaro Miki Toshinobu Seki Takashi Fujihara Yoshihiro Ishimaru Yuya Egawa 《Journal of inclusion phenomena and macrocyclic chemistry》2017,89(3-4):281-288
A boronic acid-appended γ-cyclodextrin (BA-CyD) was synthesized as a hybrid cross-linker of polyvinyl alcohol (PVA) to form a new type of hydrogel. The CyD moiety of BA-CyD forms an inclusion complex with the PVA chain to produce a mechanically interlocking structure. At the same time, the BA moiety of BA-CyD forms covalent bonds with the 1,3-diol moieties of PVA. On the basis of these two modes of interaction, the hybrid cross-linker connects two PVA chains, thus resulting in the formation of a hydrogel. To investigate the possibility of this hydrogel becoming the basis for an intelligent material for drug delivery, sugar-responsive drug release from the hydrogel was demonstrated. 相似文献
77.
Yuko Takao Tomoaki Masuoka Koji Yamamoto Tadashi Mizutani Fukashi Matsumoto Kazuyuki Moriwaki Koichi Hida Toshiyuki Iwai Takatoshi Ito Takumi Mizuno Toshinobu Ohno 《Tetrahedron letters》2014
Novel fluorinated subnaphthalocyanine derivatives were newly designed and synthesized as donor materials for low molecular organic photovoltaic cells using fullerene as an acceptor. They were designed to have the low-lying HOMO energy levels for improvement of open circuit voltage without any expense of short-circuit current density. The HOMO/LUMO energy levels of hexafluoro-, heptafluoro-, dodecafluoro-, tridecafluoro- and the parent subnaphthalocyanine estimated based on the photoelectron spectroscopy were −5.69/−3.93, −5.67/−3.90, −5.96/−4.19, −5.92/−4.11 and −5.30/−3.58 eV, respectively, showing that frontier orbital energy levels can be effectively tuned by fluorination. 相似文献
78.
Korenaga T Nomura K Onoue K Sakai T 《Chemical communications (Cambridge, England)》2010,46(45):8624-8626
α,α,α-Trifluoroacetophenone (2), which is susceptible to noncatalytic reduction by BH(3), could be reduced to chiral alcohol up to 90% ee by using electronically tuned-CBS catalyst (1) with BH(3). The enantioselectivities highly correlated with the differential orbital energies between 1-BH(3) adduct and 2, which were calculated by DFT method. 相似文献
79.
80.
Toshinobu Suzuki Masahiko Okazaki Keiryo Mitsuhashi 《Journal of heterocyclic chemistry》1986,23(3):935-939
The title compound was reacted with four types of electrophiles and the respective reaction sites were investigated. The reaction with aryl isocyanates in the conventional way yielded the corresponding ureas. In the presence of triethylamine, the 3-amino group was diacylated with acyl chlorides. On the other hand, in the cases with arylsulfonyl chlorides and p-nitrobenzaldehyde under similar conditions, the methyl group at 5-position was preferentially attacked to give arylsulfonylmethyl and p-nitrostyryl derivatives, respectively. 相似文献