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21.
H Nukaya H Watanabe H Ishida K Tsuji Y Suwa K Wakabayashi M Nagao T Sugimura T Kosuge 《Chemical & pharmaceutical bulletin》1991,39(2):533-535
The pyrolysis product of creatine showed potent mutagenic activity to Salmonella typhimurium TA98 with metabolic activation by S9 mix. One of the mutagenic substances in creatine pyrolysate was isolated and named Cre-P-1. Its structure was determined by X-ray crystallography to be 4-amino-1,6-dimethyl-2-methylamino-1H,6H-pyrrolo[3,4-f]benzimidazole- 5,7-dione. Cre-P-1 is the first registered mutagenic heterocyclic amine containing oxygen atoms in the molecule, that has been isolated from pyrolysis products. 相似文献
22.
Tashiro Shinichi Miki Satoshi Murphy Anthony B. Tanaka Manabu Kisaka Yuji Kimura Fumiaki Suwa Tomone Takahashi Yoshikazu 《Plasma Chemistry and Plasma Processing》2022,42(1):229-245
Plasma Chemistry and Plasma Processing - In arc welding, a groove is often used between metal pieces being welded. In tungsten inert gas welding of high-manganese stainless steels with arc voltage... 相似文献
23.
Kou Hiroya Yusuke Ichihashi Yoshihiro Suwa Tetsuro Ikai Kiyofumi Inamoto Takayuki Doi 《Tetrahedron letters》2010,51(29):3728-3731
The C2-side chain hydroxyl group of 1,3-cycloalkanedione discriminates between two ketones depending on its chirality. It chooses one ketone to form hydrogen bond with the oxygen atom of the TBDPS-oxymethyl group, but chooses the other ketone upon conversion to the isopropyl acetal. Two optically pure diastereomers, whose absolute configuration at the angular position is opposite for each other, were thus synthesized from this single chiral source through simple operations. This method may be applied for the synthesis of a variety of compounds with asymmetric quaternary centers. 相似文献
24.
Otsuki J Suwa K Narutaki K Sinha C Yoshikawa I Araki K 《The journal of physical chemistry. A》2005,109(35):8064-8069
The isomerization behaviors of 2-(phenylazo)imidazole (Pai-H) and 1-N-methyl-2-(phenylazo)imidazole (Pai-Me) have been investigated. The crystal structure of trans-Pai-Me was determined, revealing that key structures around the azo group are nearly identical among azobenzene, Pai-H, and Pai-Me. Pai-Me undergoes reversible cis/trans photoisomerization, whereas Pai-H responds poorly to irradiation. The quantum yields of trans-to-cis isomerization of Pai-Me on 454 and 355 nm excitation are 0.35 +/- 0.03 and 0.25 +/- 0.03, respectively, in toluene. The wavelength-dependent isomerization quantum yield is well-known for azobenzene, but these values are substantially higher than those of azobenzene. The activation energy of thermal cis-to-trans isomerization of Pai-Me in toluene is 79.0 +/- 3.5 kJ mol(-1), which is lower than that of azobenzene by 15 kJ mol(-1). The thermal cis-to-trans isomerization of Pai-H is even faster. Density functional theory calculations were performed, revealing that the energy gaps between the azo n-orbital and the highest pi-orbital of azoimidazoles are much narrower than that of azobenzene. Finally, a preliminary study suggested that metal ions can modulate the absorption spectrum of Pai-Me without a loss of the gross photochromic behavior. 相似文献
25.
Y. Masada K. Hashimoto T. Inoue Y. Sumida T. Kishi Y. Suwa 《Journal of separation science》1979,2(7):400-404
A novel method is described for the preparation of stable glass capillary columns (glass open tubular columns), including the etching and formation of a polymer film on the inner glass capillary surfaces. The approach used here is based on low-temperature plasma etching and polymerization. Under the influence of a field of radio frequency discharge, low pressure gases of fluoric compounds, introduced into the glass capillary tube, generate excited fluorine radicals which etch the inner surface. The plasma of organosilicone monomer in the glass capillary yields a uniform polymerized film on the inner surface. The resultant material functions as a good stationary phase for glass capillary gas chromatography (GC2). The inner surfaces treated with such a plasma, can be studied by means of a scanning electron microscope (SEM). The flexibility of this method permits the use of various stationary phases and surface modification. 相似文献
26.
Shigeyuki S
miya Takao Kumaki Kazumitsu Hishinuma Zenjiro Nakai Tokuji Akiba Yukio Suwa 《Progress in Crystal Growth and Characterization of Materials》1991,21(1-4):195-198
Since 1980 much attention has been payed to hydrothermal processing. There are several papers related to hydrothermal fine Zirconia powders by authors 1), 2), 3) and 3).
The authors 3) prepared ZrO2 and Y2O3-ZrO2 powders under hydrothermal conditions. Several methods were used to prepare fine ZrO2 powders under hydrothermal conditions: hydrothermal precipatation, hydrothermal crystallization, hydrothermal oxidation, hydrothermal decomposition, hydrothermal synthesis, hydrothermal anodic oxidation, RESA (reactive electrode submerged arc) process, etc.
This paper describes hydrothermal precipatation processing of ZrO2 and Y-ZrO2 powder. 相似文献
27.
Takeshi Suwa Terutaka Watanabe Tadao Seguchi Jiro Okamoto Sueo Machi 《Journal of polymer science. Part A, Polymer chemistry》1979,17(1):111-127
The size, distribution, and number of PTFE particles formed by radiation-induced emulsifier-free polymerization were measured by electron microscope and automatic particle analyzer (centrifugation method). From the electron micrographs we found that the particles are formed within 5 min. The change in the number of polymer particles (np) with reaction time (t) depends on the relative concentration of growing polymer chains to stabilizing species produced by the radiolysis of water and monomer; that is, it was governed by TFE pressure/dose rate ratio and classified into three cases: case I, dnp/dt = 0 (e.g., at 3 × 104 rad/hr and 20 kg/cm2); case II, dnp/dt < 0 (e.g., at dose rate below 1.9 × 104 rad/hr and 20 kg/cm2); case III, dnp/dt > 0 (e.g., at 3 × 104 rad/hr and 2 kg/cm2). The polymer molecular weight above 106 is almost independent of the particle size. The polymerization loci are mainly on the surface of polymer particles dispersed in the aqueous phase in cases I and II except in the initial stage. In case III new particles are formed successively during polymerization. Therefore the polymerization loci are mainly in the aqueous phase. Especially in case I, we concluded that after the generation of particles the propagation proceeds mainly on the surface of polymer particles like the core shell model proposed by Granico and Williams. 相似文献
28.
Takeshi Suwa Tadao Seguchi Masaaki Takehisa Sueo Machi 《Journal of Polymer Science.Polymer Physics》1975,13(11):2183-2194
Melting and crystallization behavior of polytetrafluoroethylene as polymerized in emulsion and suspension is shown to depend on molecular weight. DSC heating curves for virgin PTFE with low molecular weight below 3 × 105 have a single peak, whereas curves for higher molecular weight samples have double peaks. With increasing heating rate the areas of higher melting peaks become larger than the lower melting peaks. The morphology of polymer exhibiting double melting peaks is mainly folded ribbons or granular particles. The phenomenon of double melting is explained on the basis of two different crystalline states which correspond to the “fold regions” and the “linear segments” in a folded ribbon. The melting temperature of virgin PTFE is almost constant at ca. 330°C for molecular weights below 1 × 106, and rises as the molecular weight increases above 1 × 106. The heat of melting of virgin PTFE is nearly independent of molecular weight. On the basis of these results, we propose a model for melting and crystallization of low and high molecular weight PTFE and for the crystal structure. 相似文献
29.
J.-P. Brasselet D. Lehmann J. Seade T. Suwa 《Transactions of the American Mathematical Society》2002,354(4):1351-1371
Let be a compact local complete intersection defined as the zero set of a section of a holomorphic vector bundle over the ambient space. For each connected component of the singular set of , we define the Milnor class in the homology of . The difference between the Schwartz-MacPherson class and the Fulton-Johnson class of is shown to be equal to the sum of over the connected components of . This is done by proving Poincaré-Hopf type theorems for these classes with respect to suitable tangent frames. The -degree component coincides with the Milnor numbers already defined by various authors in particular situations. We also give an explicit formula for when is a non-singular component and satisfies the Whitney condition along .
30.
We propose that a chain of five-membered rings (polyaminotriazole) should be ferromagnetic with an appropriate doping that is envisaged to be feasible with a field-effect transistor structure. The ferromagnetism is confirmed by a spin density functional calculation, which also shows that ferromagnetism survives the Peierls instability. We explain the magnetism in terms of the Mielke and Tasaki flatband ferromagnetism with the Hubbard model. This opens a new possibility of band ferromagnetism in purely organic polymers. 相似文献