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71.
Naozumi Teramoto Toyoki Motoyama Ryutoku Yosomiya Mitsuhiro Shibata 《European Polymer Journal》2003,39(2):255-261
High amylose corn starch (HACS) was etherified with 1-bromopropane in dimethyl sulfoxide. The structure of the products was characterized by infra-red and 1H-NMR spectroscopy. The degree of substitution (DS) on glucose unit calculated from 1H-NMR spectrum was varied from 0.9 to 2.7 by changing feed ratio of 1-bromopropane to HACS. Thermogravimetric analysis reveals that the etherified HACS has a higher decomposition temperature than unmodified HACS. Differential scanning calorimetry analysis reveals that the etherified starch has a clear glass transition temperature which decreased with increasing DS, and that no melting point is observed. This result demonstrates that the etherified HACS mainly consists of amorphous region. The biodegradation rate decreases with increasing degree of etherification. 相似文献
72.
Masanobu Watanabe Izumi Motoyama Hirotoshi Sano 《Journal of organometallic chemistry》1996,510(1-2):243-253
Oxidation of [1.1]ferrocenylruthenocenophane with a large excess and 1.5 equivalents of iodine gives dicationic iodo[1.1]ferrocenylruthenocenophanium2+I3− · 0.5I22 (1) and monocationic [1.1]ferrocenylruthenocenophanium+I3− (2) salts respectively. The structures of 1 and 2 were analyzed by single-crystal X-ray diffraction studies. The crystal form of 1 is monoclinic space group C2/c, A = 21.35](5), B = 20.594(5), C = 17.397(4) Å, β = 124.17(1)°, Z = 8, and the final R = 0.068 and Rw = 0.070. The cation formulated as [FeIII(C5H4CH2C5H4)2RuIVI]2+ exists in a syn-conformation as in the cases of the neutral compound. The distance between the RuIV and FeII is 4.656(4) Å, which is much shorter than the value of the neutral compound (4.792(2) Å), and the bond angle of I---RuIV,FeIII is 81.26°. The dihedral angle between the two η5-C5H4 (fulvenide) rings on the RuIV moiety is 37.56° due to the RuIV---I bond (2.758(3) Å). These two rings of FeIII and RuIV moieties are essentially eclipsed. The unit cell has three kinds of I3− (I3a−, I3b− and I3c−) and one I2, and the formula of 1 is given as [FeIII(C5H4CH2CSH4)2RuIVI]2+I3− · 0.5(I3−)2 · 0.5I2. The crystal of 2 formulated as [FeIII(C5H4CH2C5H4)2RuII]+I3− is triclinic space group
, and the final R = 0.067 and Rw = 0.068. The unit cell has two independent molecules (unit A and B); i.e. two kinds of distance between the RuII and FeIII, are observed; one (A) is 4.615(3) and the other (B) is 4.647(3) α. The two η5-C5H4 rings of both FeIII and RuII are essentially staggered and the dihedral angles between the rings of FcH and RcH moieties are less than 5.8°. Typical ferrocenium-type broad singlet 57Fe-Mössbauer lines are observed for both salts (1, 2) at all temperatures. 相似文献
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73.
74.
Takayuki Tsukegi Toru Motoyama Haruo Nishida Takeshi Endo 《Polymer Degradation and Stability》2007,92(4):552-559
To control the depolymerization process of poly(l-lactic acid) into l,l-lactide for feedstock recycling, the racemization of l,l-lactide as a post-depolymerization reaction was investigated. In the absence of a catalyst, the conversion to meso-lactide increased with increase in the heating temperature and time at a higher rate than the conversion into oligomers. The resulting high composition of meso-lactide suggests that the direct racemization of l,l-lactide had occurred in addition to the known racemization mechanism that occurs on the oligomer chains. In the presence of MgO, the oligomerization rapidly proceeded to reach an equilibrium state between monomers and oligomers. The equilibrium among l,l-, meso-, and d,d-lactides was found to be a convergent composition ratio l,l-:meso-:d,d-lactides = 1:1.22:0.99 (wt/wt/wt) after 120 min at 300 °C. This composition ratio also indicates that in addition to the known racemization reaction on the oligomer chains, direct racemization among the lactides is also a frequent occurrence. 相似文献
75.
Toru Motoyama Takayuki Tsukegi Yoshihito Shirai Takeshi Endo 《Polymer Degradation and Stability》2007,92(7):1350-1358
To control the depolymerization of poly-l-lactic acid (PLLA) into l,l-lactide, effects of altering the physical and chemical properties of magnesium oxide (MgO) on its ability as a catalyst were investigated. Four kinds of MgO particles: MgO-heavy, 0.2, 0.05, and 0.01 μm, having primary particles of different dimensions, surface areas, and chemical structures/species were used. Thermo-gravimetric profiles of PLLA/MgO composites shifted into a lower temperature range due to an increase in the catalytic surface area resulting from a decrease in the dimensions of the MgO particles. However, decreasing the dimensions caused frequent side reactions with unfavorable products: cyclic oligomers and meso-lactide, due to the presence of different chemical structures/species. Heat treatment of the MgO particles not only effectively suppressed the oligomer production and enhanced the l,l-lactide production, but also accelerated the meso-lactide production at lower temperatures. These results indicate that the surface properties of MgO considerably influence the depolymerization of PLLA, with the catalytic behavior of MgO controllable by heat treatment and selection of the depolymerization conditions. 相似文献
76.
Ishigami N Ago H Motoyama Y Takasaki M Shinagawa M Takahashi K Ikuta T Tsuji M 《Chemical communications (Cambridge, England)》2007,(16):1626-1628
We have fabricated a microreactor incorporating vertically-aligned carbon nanotubes supporting Pt nanoparticles and found that the presence of aligned nanotubes significantly enhances the catalytic reaction and extends the catalyst lifetime as compared with conventional microreactors using a Pt metal film or Pt nanoparticles directly deposited on the channel walls. 相似文献
77.
78.
Tatsunori Hirotsu Taishi Higashi Keiichi Motoyama Fumitoshi Hirayama Kaneto Uekama Hidetoshi Arima 《Journal of inclusion phenomena and macrocyclic chemistry》2014,80(1-2):107-112
Recently, a large number of peptides and proteins have been utilized as active pharmaceutical ingredients in the clinical field. However, the stability of peptide and protein drugs is often low. In addition, some peptides and proteins adsorb onto glass or polypropylene tube. In the present study, to improve these pharmaceutical properties of peptides and proteins, we newly prepared glucuronylglucosyl-β-cyclodextrin (GUG-β-CyD) conjugate with insulin, a model protein drug, and evaluated its enzymatic or thermal stability and adsorption onto glass or polypropylene tube. The insulin conjugate with GUG-β-CyD was successfully prepared by condensation of amine group of insulin and carboxyl group of GUG-β-CyD. Circular dichroism spectra showed that the secondary structure of insulin in this conjugate was retained. Adsorption of insulin onto glass or polypropylene tube was decreased by the conjugation with GUG-β-CyD. Moreover, enzymatic and thermal stabilities of the conjugate were higher than those of insulin and the mixture of insulin and GUG-β-CyD. These results suggest that insulin conjugation with GUG-β-CyD could improve the pharmaceutical properties of insulin. 相似文献
79.
Hatsumi Nakazawa Shinobu Fujinami Miho Motoyama Takao Ohta Takeaki Araki Hajime Tanaka 《Molecular Crystals and Liquid Crystals》2013,570(1):871-878
Abstract Polymerization-induced phase separation in polymer-dispersed liquid crystal is studied by computer simulations in two dimensions. The domain morphology resulting from phase separation is investigated by solving the couple set of equations for the local volume fraction and the nematic order parameter, taking into account the viscoelastic effects and gelation due to polymerization. Comparing the morphology of phase separation by temperature quench, it is shown that the viscoelastic effects and gelation enable the polymer-rich phase to form a stable interconnected domain even when the polymer component is minority. 相似文献
80.
Chemoselective hydrogenation of nitroarenes with carbon nanofiber-supported platinum and palladium nanoparticles 总被引:1,自引:0,他引:1
Platinum and palladium nanoparticles supported on three types of carbon nanofibers (CNFs) are synthesized and used as catalysts in the hydrogenation of nitroarenes. Nanosized platinum particles dispersed on platelet-type CNF efficiently catalyze the reduction of functionalized nitroarenes to the corresponding substituted anilines in high turnover numbers with other functional groups remaining intact. 相似文献