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221.
Hydroxyapatite-bound cationic ruthenium complexes as novel heterogeneous lewis acid catalysts for Diels-Alder and aldol reactions 总被引:2,自引:0,他引:2
Mori K Hara T Mizugaki T Ebitani K Kaneda K 《Journal of the American Chemical Society》2003,125(38):11460-11461
Creation of a stable and well-defined active center on a solid surface is a promising protocol for designing more efficient hybrid-catalysts that bridge the gap between homogeneous and heterogeneous catalysis. Treatment of a hydroxyapatite-bound Ru complex (RuHAP) with an aqueous solution of AgX (X = SbF6-, TfO-) afforded a new type of cationic Ru phosphate complex, having potentially vacant coordination sites. These cationic RuHAPs exhibited Lewis acidity toward carbonyl and cyano groups, promoting Diels-Alder and Aldol reactions with high efficiencies. Moreover, no Ru leaching was detected in the above organic reactions, and then the catalysts were recyclable. 相似文献
222.
Kazuo Itoh Masahiko Chikuma Mieko Nishimura Tomoo Tanaka Motoko Tanaka Morio Nakayama Hisashi Tanaka 《Fresenius' Journal of Analytical Chemistry》1989,333(2):102-107
Summary A sulfonic acid derivative of bismuthiol-II (bisIIS) was synthesized from 4-hydrazinobenzene sulfonic acid and carbon disulfide. Selenium(IV) was adsorbed selectively and quantitatively on the anion-exchange resin loaded with bis-IIS. Selenium adsorbed on the resin was eluted by the use of penicillamine and determined by hydride generation atomic absorption spectrometry (hydride generation/AAS). Selenium(VI) and other forms of selenium, which were not adsorbed onto the resin, were collected on the resin after digestion with nitric acid followed by reduction with hydrochloric acid. Separative preconcentration of selenium(IV), selenium(VI) and other forms of selenium in 0.5 mol/l sodium chloride could be carried out successfully by the proposed procedures. However, in the case of estuarial sea water containing a large quantity of organic substances, selenium(IV) could not be separated, because organic substances interfered with the reduction of selenium(VI) to selenium(IV) by the use of hydrochloric acid. Selenium(IV) and total amount of selenium(VI) and other forms of selenium dissolved in polluted sea water samples were determined by the proposed procedures.
Bestimmung von Selen (IV) und anderen in Meereswasser gelösten Selenformen mit Hilfe eines mit dem Sulfonsäurederivat von Bismuthiol-II beladenen Anionenaustauschers und der Hydrid-AAS相似文献
223.
Hong Hai Tomoo Miura Tomoyoshi Kobayashi Yuichiro Maéda Masao Miki 《Journal of fluorescence》2000,10(2):193
Contraction of vertebrate striated muscle is regulated by the strong Ca2+-dependent interaction among troponin (Tn), tropomyosin (Tm), and actin on the thin filament. Using fluorescence resonance energy transfer (FRET), the interactions between Tm and the Tn complex or between Tm and the Tn subunit, TnI or TnC, with or without other troponin subunits, were characterized in the presence or absence of F-actin and Ca2+ ions. Cys-190 of Tm was selectively labeled with the acceptor probe, 4-dimethylaminophenylazophenyl 4-maleimide. Troponin was selectively labeled at position 9 or 133 of TnI and position 98 of TnC with a donor probe, 5-(2-iodoacetylaminoethyl)aminonaphtha lene 1-sulfonic acid. FRET measurements indicate that the interaction between TnI and Tm alone is very weak, but that in the presence of F-actin, TnI binds to the proper binding site on Tm even in the absence of TnT. The distances between Cys-190 of Tm on F-actin and Cys-9 or Cys-133 of Tnl or Cys-98 of TnC in the reconstituted Tn were determined to be 52.8, 53.7, Å and 56.5 Å, respectively, in the absence of Ca2+, indicating that the Tnl—TnC complex, the globular portion of Tn, is located near Cys-190 of Tm on the reconstituted thin filaments. Upon binding of Ca2+ to TnC, these distances increased by 5.6 and 1.4 Å or decreased by 5.4 Å, respectively. These Ca2+-induced changes in Tn—Tm seem to occur only when F-actin is present, suggesting that the stable complex formation of TnI with the outer domain of F-actin upon removal of Ca2+ is a very important event during inhibition. 相似文献
224.
Asami Yoshii Yuzuka Onaka Koki Ikemoto Tomoo Izumi Sota Sato Hiroshi Kita Hideo Taka Hiroyuki Isobe 《化学:亚洲杂志》2020,15(14):2181-2186
Oligo‐meta‐phenylenes have been designed and synthesized as multipotent base materials of single‐layer organic light‐emitting devices. Simple molecular structures of oligo‐meta‐phenylenes composed of linear phenylene arrays benefited from the wealth of modern reactions available for biaryl couplings and were concisely synthesized in a series. Structure‐performance relationship studies with the first seven congeners revealed key features important for the multipotent materials in single‐layer devices. As a result, highly efficient phosphorescent electroluminescence was made possible in a highly simplified device architecture comprising one‐region, single‐layer configurations. Detailed investigations with hole‐only devices disclosed that the hole mobility was effectively retarded by potent materials, which should facilitate hole/electron recombination for electroluminescence. 相似文献
225.
Arata Yajima Saki KounoTohru Dairi Manami MogiRyo Katsuta Haruo SetoTomoo Nukada 《Tetrahedron letters》2011,52(38):4934-4937
The first synthesis of (±)-cyclic dehypoxanthine futalosine (cyclic DHFL), a biosynthetic intermediate in the futalosine pathway for menaquinones operating in microorganisms, has been achieved. Efficient growth of the Streptomyces coelicolor mutant, which lacks the cyclic DHFL synthetase gene (mqnC gene) was observed in the presence of synthetic (±)-cyclic DHFL. 相似文献
226.
Four stereoisomers of Phytophthora mating hormone α2 were synthesized using both enantiomers of citronellol as starting materials. The absolute configuration of the natural product was determined to be 7S,11R,15R by oospore-inducing assays of the synthetic isomers. A concise synthetic procedure of α1 was also established using a common synthetic intermediate of α2. 相似文献
227.
228.
Some random copolymer blends have been found to be miscible in a certain range of copolymer composition even though any combinations of their corresponding homopolymers are not miscible. The opposite case may exist. These two types of miscibility behaviors have been called miscibility and immiscibility windows, respectively. Such two miscibility behaviors were discussed by application of the equation-of-state theory to copolymer systems. The equation-of-state theory gives two kinds of temperature dependences of the interaction parameter X: (a) a U-shaped curve which is always positive regardless of temperature and (b) a function increasing monotonically from negative to positive values. Infinite molecular weight polymer blends are immiscible over all the temperature in the case (a), while in the case (b) two polymers are miscible below a temperature at which X=0. Applying the equation-of-state theory to random copolymer blends in which miscibility changes with the copolymer composition at a certain temperature to be immiscible → miscible → immiscible, two types of dependences of the temperature-X curve can be obtained: (1) (a) → (b) → (a) dependent on the copolymer composition and (2) (b) regardless of the copolymer composition. For the blends in which miscibility changes with the copolymer composition to be miscible → immiscible → miscible, there can be two types: (3) (b) → (a) → (b) and (4) (b) regardless of the copolymer composition. It may be concluded that socalled miscibility and immiscibility windows should be defined by the types (1) and (3), respectively. The equation-of-state theory for random copolymer systems was applied to the real systems. The blends of poly(vinyl acetate-co-vinyl chloride) and poly(ethylene-co-vinyl acetate) were of the type (1), while it was suggested that the blends of poly(vinyl acetate-co-vinyl chloride) and poly(isobutyl methacrylate-co- butyl methacrylate) may be of the type (4) though this system behaved like an immiscibility window at a certain temperature. 相似文献