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31.
Maria Chiara Munisso Satomi Yano Wenliang Zhu Giuseppe Pezzotti 《Continuum Mechanics and Thermodynamics》2008,20(3):123-132
The main aim of this work is a precise experimental assessment of the local stress fields developed at the notch-root in a
ruby crystal, selected as a paradigm brittle material, by means of photo- and electron-stimulated luminescence techniques.
Our approach takes advantage of the piezo-spectroscopic (PS) effect, which consists of a spectral shift of the luminescence
emitted by the material due to lattice strain. Highly spatially resolved stress maps were extensively collected at the notch-root
and spectral shifts monitored for the chromophoric (R-lines) fluorescence observed in a single-crystalline ruby sample. Experimental data were analyzed and compared to the theoretical
solutions of notch-root stress fields given by Filippi and by Creager-Paris. Due to its inherent simplifications, the Creager–Paris
solution was found leading to underestimation of the maximum stress value piled up in the material, while the Filippi’s solution
represented a more suitable approximation for the stress field developed at the notch-root. 相似文献
32.
Satomi Niwayama Elizabeth M. Holt 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(7):e300-e301
The title compound, C12H16O6, prepared by a standard synthetic method, was determined by single‐crystal X‐ray crystallography to exist with a cyclopropane ring fused to a cyclopentene ring. Comparison of the unit‐cell dimensions and space group of this material with those of a crystal of the same material prepared using a route involving pig liver esterase hydrolysis shows them to be identical. 相似文献
33.
34.
The conditions of the practical selective monohydrolysis of symmetric diesters we previously reported have been modified and applied to selective monohydrolysis of bulky symmetric diesters. While ultrasound is generally considered effective for two-phase reactions, its effect actually turned out to be rather marginal. Instead, use of a larger proportion of a polar aprotic co-solvent, DMSO, and aqueous KOH helped enhance the reaction rates and improve the yields of the half-esters. The reactions are simple, mild and practical without special devices. 相似文献
35.
Akihiro Imamura Hiromune Ando Satomi KorogiGenzoh Tanabe Osamu MuraokaHideharu Ishida Makoto Kiso 《Tetrahedron letters》2003,44(35):6725-6728
We have discovered an unusual α-galactosylation using phenylthioglycoside of 4,6-O-di-tert-butylsilylene (DTBS)-protected galactose derivatives as a glycosyl donor, which was not hampered by the neighboring participation of C-2 acyl functionality such as NTroc and OBz. The power of the DTBS effect has been exemplified by the coupling reaction with various glycosyl acceptors. 相似文献
36.
Igarashi Y Kumazawa H Ohshima T Satomi H Terabayashi S Takeda S Aburada M Miyamoto K 《Chemical & pharmaceutical bulletin》2005,53(9):1088-1091
We describe the synthesis of 2-[(4-hydroxyphenyl)thio]-7-isopropoxy-5,6-dimethoxy-4H-chromen-4-one 2 from 3,4,5-trimethoxyphenol 6 via the key intermediate, 3-iodo-7-isopropoxy-5,6-dimethoxy-4H-chromen-4-one 3. An important feature of this synthetic scheme involves selective alkylation, which can be achieved by two different routes. One route involves the selective isopropylation of a triacetate derivative 4 under basic conditions. The second route employs the selective demethylation of a trimethoxy derivative 5 under acidic conditions followed by isopropylation. The product of these alternative routes, compound 3, is then converted to a capillarisin sulfur analogue 2 in a one-pot reaction via the imidazolyl intermediate 22. 相似文献
37.
13C NMR spectroscopic studies were performed for carbonyl compounds having a hydroxyl group, a carboalkoxy group, an acetoxy group, or a carboxyl group in various solvents with different polarities for observation of their behaviors of 13C NMR chemical shifts of carbonyl carbons in solutions. It was found that the chemical shifts of the carbonyl carbons in 13C NMR have good correlation with the empirical parameter for solvent polarities, ETN, depending on the structures. Inter- or intramolecular hydrogen bonding and dipolar-dipolar interactions appear to play a key role in this observation. 相似文献
38.
Tryptophan (Trp), an aromatic amino acid, is a constituent of peptides/proteins and is also a precursor of serotonin, kynurenine derivatives, and nicotinamide adenine dinucleotides. There have been a number of reports on photochemical reactions involving peptides/proteins which contain Trp that showed significant photodegradation, dimerization, and photoionization. The photochemical properties of Trp have not been fully elucidated, and this would provide novel insight into the handling of Trp-containing peptides/proteins. Consequently, we have been trying to evaluate the photochemical properties of Trp, as well as other essential amino acids, focusing on their photosensitivity, photodegradation, and their ability to induce lipid peroxidation. Among all the essential amino acids tested, Trp exhibited the maximal level of superoxide anion generation under 18 h of light exposure (30000 lux). UV spectral analysis of Trp suggested the absorbability of UVA/B light, and exposure of Trp, in both solid and solution states, to UVA/B light resulted in significant photodegradation (t(0.5): 18 h) and gradual color changes. In addition, photoirradiated Trp generated lipoperoxidant, a causative agent of photoirritation, and this might be associated with ROS generation. 相似文献
39.
Chotika Viriyarattanasak Motoo Shiro Shigeru Munekawa Felix Franks Satomi Ikeda Kazuhito Kajiwara 《Acta Crystallographica. Section C, Structural Chemistry》2015,71(11):954-958
Raffinose [or O‐α‐D‐galactopyranosyl‐(1→6)‐α‐D‐glucopyranosyl‐(1→2)‐β‐D‐fructofuranoside] pentahydrate, C18H32O16·5H2O, (I), and three lower hydrates, namely the 4.433‐, (II), 4.289‐, (III), and 4.127‐hydrated, (IV), forms, obtained in the course of the dehydration of (I), have been studied. The unit cells in the space group P212121 are of similar dimensions for all the crystals. The conformation of the raffinose molecules remains almost the same across the four crystal structures. The raffinose molecules are linked into a three‐dimensional hydrogen‐bonded network involving all the –OH groups, the ring and glycosidic O atoms, and the water molecules. Six water sites were identified in the structures of (II), (III) and (IV), of which W1, W4 and W6 (W = water) are partially occupied with their populations coupled. W1, W4 and one of the –OH groups of the galactose ring form an infinite hydrogen‐bonding chain around a 21 axis parallel to the a axis (denoted chain A), and W6 and the same –OH group form a similar chain (chain A′) disordered with chain A. The occupancy ratio of chain A to chain A′ for N‐hydrates (N is a hydration number between 4 and 5) is (N− 4):(5 −N). The transformation of chain A to chain A′ as part of the dehydration process has little effect on the rest of the structure. Thus, the dehydration proceeds without significant impact on the crystal structure. 相似文献
40.
Daisuke Yasokawa Satomi Murata Yumiko Iwahashi Emiko Kitagawa Ryoji Nakagawa Tazusa Hashido Hitoshi Iwahashi 《Applied biochemistry and biotechnology》2010,160(6):1685-1698
To assess the toxicity of the C1 compounds methanol and formaldehyde, gene expression profiles of treated baker’s yeast were
analyzed using DNA microarrays. Among approximately 6,000 open reading frames (ORFs), 314 were repressed and 375 were induced
in response to methanol. The gene process category “energy” comprised the greatest number of induced genes while “protein
synthesis” comprised the greatest number of repressed genes. Products of genes induced by methanol were mainly integral membrane
proteins or were localized to the plasma membrane. A total of 622 and 610 ORFs were induced or repressed by formaldehyde,
respectively. More than one-third of the genes found to be strongly repressed by formaldehyde belonged to the “protein synthesis”
functional category. Conversely, genes in the subcategory of “nitrogen, sulfur, and selenium metabolism” within “metabolism”
and in the category of “cell rescue, defense, and virulence” were up-regulated by exposure to formaldehyde. Our data suggest
that membrane structure is a major target of methanol toxicity, while proteins were major targets of formaldehyde toxicity. 相似文献