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Yoshimi Kurimura Masahiro Saito Kyota Hiramatsu Yoshihiro Sairenchi 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(9-11):1275-1292
Electron transfer reactions of Co(NH3)5PAA (PAA = polyacrylic acid) with either the polyanionic polymer-bound ferrous chelate, Fe11P-SS (P-SS = vinylbenzylaminediacetate-co-styrenesulfonate) or the uncharged polymer-bound ferrous chelate, Fe11P-VPRo (P-VPRo = vinylbenzylaminediacetate-co-vinylpyrrolidone), and the Ru(bpy)2+ 3 photosensitized reduction of Co(NH3)5PAA have been investigated in aqueous solutions at pH 5.4, I = 0.06 (I is ionic strength), and 25°C. For the ferrous chelate reductions, the second-order rate constants for Fe11-PSS and Fe11P-VPRo were almost equal to that for the corresponding nonpolymer-bound ferrous chelate, Fe11BDA (BDA = benzylaminediacetate). The results indicate that there is no appreciable steric hindrance due to the polymer chains of the polymer-bound ferrous chelates and that the effect of columbic repulsion force between the polyanion chains can be ignored for the reaction of Co(NH3)5PAA with Fe11P-SS. The results also suggest that there are two kinds of the pendant Co(III) species, “reactive” and “inert.” The inert Co(III) species are shielded by the polymer chains from attack of the Fe(II) chelates that are present in the bulk solutions. A similar reaction behavior was observed in the Ru(bpy)2+ 3 photosensitized reduction of Co(NH3)5PAA at pH 5.4. For the Co(III) complex having an extremely few Co(III) complex moieties on the polymer chain, almost all of the Co(III) groups were hardly reduced by the excited state of Ru(bpy)2+ 3, and reverse quenching occurred due to binding of the Ru(bpy)2+ 3 to the polyacrylic acid chain of the polymer complex. On the other hand, for Co(NH3)5PAA with a relatively large number of the Co(III) moieties on the polymer chain, lifetime measurements at a higher concentration of the Ru(bpy)2+ 3 showed a double-exponential fit, which suggests that there are two parallel decay processes. The fast and slow components mainly correspond to the decays: Ru(bpy)2+ 3 quenched by Co(III) and reverse quenching due to binding of Ru(bpy)2+ 3 into the compact polymer chains. 相似文献
23.
Alkylesters of orthophosphoric acids have been used for alkylation of phenols1, anilines2, and nitrogen heterocyclic compounds.3 However, no example is reported on their use as an alkoxylating agent for aromatic amines. We have found that alkyl phosphates can act as alkoxylating agents for aromatic diamines in the presence of H2O or aqueous H3PO4. We now report the one-step dialkoxylation of aromatic diamines such as diaminoanthracene and -naphthalene by trialkyl phosphates. 相似文献
24.
Tubiferal A, a triterpenoid isolated from myxomycete Tubifera dimorphotheca, exhibits a reversal effect of vincristine (VCR) resistance against VCR-resistant KB cell lines. The compound possesses a complex structure involving the 6-7-6-5 polycyclic carbon framework with various functional groups. The stereoselective synthesis of the right-hand segment of tubiferal A was achieved on the basis of the cyclopentene annulation method and the semi-pinacol rearrangement reaction of an epoxy alcohol for constructing the trans-fused 6-5 bicyclic skeleton possessing two quaternary carbon atoms at the angular positions. 相似文献
25.
Cathodoluminescence (CL) from InGaN grown on GaN hexagonal pyramid structures has been investigated. The facet structure can be controlled by the growth temperature and reactor pressure. GaN pyramid structures surrounded with facets were grown at 1020 C at a pressure of 500 Torr by low-pressure metalorganic vapor phase epitaxy (LP-MOVPE). The indium mole fraction in the InGaN film depends on the facet structure. The thickness of the InGaN and the peak wavelength and intensity of the CL from the InGaN gradually increased from the bottom to the top of the facets. 相似文献
26.
Non‐Heme Dioxygenase Catalyzes Atypical Oxidations of 6,7‐Bicyclic Systems To Form the 6,6‐Quinolone Core of Viridicatin‐Type Fungal Alkaloids 下载免费PDF全文
Noriyasu Ishikawa Dr. Hidenori Tanaka Dr. Fumi Koyama Prof. Dr. Hiroshi Noguchi Prof. Dr. Clay C. C. Wang Prof. Dr. Kinya Hotta Prof. Dr. Kenji Watanabe 《Angewandte Chemie (International ed. in English)》2014,53(47):12880-12884
The 6,6‐quinolone scaffold of the viridicatin‐type of fungal alkaloids are found in various quinolone alkaloids which often exhibit useful biological activities. Thus, it is of interest to identify viridicatin‐forming enzymes and understand how such alkaloids are biosynthesized. Here an Aspergillal gene cluster responsible for the biosynthesis of 4′‐methoxyviridicatin was identified. Detailed in vitro studies led to the discovery of the dioxygenase AsqJ which performs two distinct oxidations: first desaturation to form a double bond and then monooxygenation of the double bond to install an epoxide. Interestingly, the epoxidation promotes non‐enzymatic rearrangement of the 6,7‐bicyclic core of 4′‐methoxycyclopenin into the 6,6‐quinolone viridicatin scaffold to yield 4′‐methoxyviridicatin. The finding provides new insight into the biosynthesis of the viridicatin scaffold and suggests dioxygenase as a potential tool for 6,6‐quinolone synthesis by epoxidation of benzodiazepinediones. 相似文献
27.
Dr. Hiromu Kashida Hidenori Azuma Ryoko Maruyama Dr. Yasuyuki Araki Prof. Dr. Takehiko Wada Prof. Dr. Hiroyuki Asanuma 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(28):11456-11459
Herein we report the construction of efficient light-harvesting antennae by hybridization of DNA oligonucleotides containing high densities of fluorophores into DNA junctions through d -threoninol. Six pyrene donors could be incorporated into each arm without self-quenching. A perylene acceptor was located at the center of the junction. Antenna effects of a duplex and three- to eight-way junctions were systematically compared. Six- and eight-way junctions had the highest antenna effects, and their effective absorption coefficients were 8.5 times higher than that of perylene. Interestingly, even-numbered junctions had higher efficiencies than odd-numbered junctions. Nondenaturing gel analyses and fluorescence lifetime measurements demonstrated that the strong odd–even effects were derived from differences in the stability of junctions. The results presented will guide the design of efficient artificial photosynthetic systems. 相似文献
28.
Hidenori Kinoshita Kazuki Yaguchi Takayuki Tohjima Katsukiyo Miura 《Tetrahedron letters》2017,58(16):1607-1610
The diisobutylaluminum hydride (DIBAL-H)-promoted benzocyclization, recently developed by this group, was adopted for the synthesis of a natural product containing a 9,10-dihydrophenanthrene skeleton to demonstrate its synthetic utility. One of the extracts from the roots of Salvia hydrangea DC. ex Bentham (Lamiaceae), a 20-norabietane derivative, was selected as the target molecule. The key step forming the 9,10-dihydrophenanthrene skeleton was achieved by the DIBAL-H-promoted cyclization of a silylated 1,3-dien-5-yne easily accessible from a substituted α-tetralone. 相似文献
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30.
Effect of sonication on the photo-catalytic mineralization of some chlorinated organic compounds 总被引:1,自引:0,他引:1
Effects of the irradiation of ultrasound (US) on the photo-catalytic mineralization of some chlorinated organic compounds such as dichloroethane, tri- and tetrachloroethylenes, chloroacetic acids and chloromethanes were examined in oxygen saturated aqueous solutions suspended titanium dioxide (P25) particles. The yields of the sonochemical mineralization for these compounds were found to be extremely low compared to the photo-catalysis. However, the pre-sonication, US irradiation on the sample solution before the photo-irradiation, enhanced significantly the following photo-catalytic degradation to the complete oxidation. The effect was investigated in detail and it was found that the effect was mainly owing to the increase in the capability of the catalysis of which particles were sparsely dispersed by the sonication. The other contribution of the pre-sonication effect was found to be "pre-sonolysis", the initial formation of some intermediated products sonochemically, which are oxidizable more rapidly further to carbon dioxide than the original compound by the following photo-catalytic reactions. The pre-sonolysis effect was observed remarkably for trichloroacetic acid and tetrachloromethane, both of which are known to be hardly reactive to the photo-catalytic degradation. The photo-catalytic degradation with simultaneous sonication were also carried out for these compounds. The synergetic effect in the mineralization was observed both for carbontetrachloride and for trichloroacetic acid, the higher carbon dioxide yield being obtained in the simultaneous reaction than the sum of the yields in the photo-catalysis and the sonolysis each alone, while no significant synergetic effect was observed in the mineralization of other compounds. 相似文献