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661.
A structure and reactivity relationship has been determined on the reaction of isopropyl and n-butyl Grignard reagents and n-butyllithium with vinyl-(alkoxy)silanes and (amino)silanes. The addition to the vinyl group has been analyzed in terms of the nucleophile HOMO-vinyl group LUMO interaction. 相似文献
662.
Kohei Uosaki Kentaro Okazaki Hideaki Kita 《Journal of polymer science. Part A, Polymer chemistry》1990,28(2):399-409
Wet poly(vinyl chloride) (wPVC) coated glassy carbon (GC) electrode was prepared by casting a DMF solution of poly(vinyl chloride) on glassy carbon and immersing it in methanol, and then in water. The wPVC coated GC (wPVC/GC) electrode showed electrochemical activity in aqueous solution; therefore, it was possible to obtain a wPVC/polypyrolle (PPy) composite by electropolymerization from aqueous solution of pyrolle (Py) into the wPVC matrix on the electrode. PPy segregated in wPVC matrix and the mechanical properties of PPy was improved by forming a composite without changing the electrochemical properties of PPy. The PPy/wPVC ratio can be controlled by controlling the concentration of PVC in DMF solution. 相似文献
663.
Two types of solid state reaction of K2[RSiF5] have been developed: (1) CuCl promoted homo coupling of alkenyl- and phenyl-silicates, and (2) formation of RH fraom alkyl- and alkenyl-silicates by heating with CuF2·2H2O. 相似文献
664.
Takayuki Otsu Kohei Shiraishi Akikazu Matsumoto 《Journal of polymer science. Part A, Polymer chemistry》1993,31(4):885-890
Di-tert-butyl maleate (DtBM) did not polymerize with 2,2′-azobis(isobutyronitrile) as a radical initiator, but DtBM easily homopolymerized via a monomer-isomerization radical polymerization mechanism to give a high molecular weight polymer when morpholine was added into the polymerization system as an isomerization catalyst. The feature of the monomer-isomerization polymerization of DtBM was investigated in detail. The polymer obtained was confirmed to consist of a poly(tert-butoxycarbonylmethylene) structure similar to that from di-tert-butyl fumarate. Subsequent pyrolysis of the resulting polymer at 180°C is a useful route to synthesis of a high molecular weight poly(fumaric acid). © 1993 John Wiley & Sons, Inc. 相似文献
665.
Yamaguchi S Shirasaka T Akiyama S Tamao K 《Journal of the American Chemical Society》2002,124(30):8816-8817
A series of dibenzoborole derivatives with various groups such as (N,N-diphenylamino)phenyl, thienyl, and bithienyl groups at the 3,7-positions have been synthesized and their photophysical properties studied. These new pi-electron systems show significant solvatochromism in the fluorescence spectra. Thus, about 100-140 nm blue shifts in the emission maxima and 20-30-fold increments in the quantum yields are observed upon changing the solvent from THF to DMF. Similar fluorescence changes are observed upon the addition of n-Bu4NF to their THF solutions, demonstrating their sensing abilities toward a fluoride ion. These fluorescence changes result from the "on/off" control of the ppi-pi* conjugation in their LUMO by the coordination of donor solvents or fluoride ion to the boron atom in the dibenzoborole skeleton. 相似文献
666.
Hidetoshi Yamada Koki Tanigakiuchi Kohei Nagao Kotaro Okajima Tatsuya Mukae 《Tetrahedron letters》2004,45(50):9207-9209
The pyranose rings of the 2,3-bis-O-tert-butyldiphenylsilyl-α- and β-d-glucopyranoses, and of the 2,3-bis-O-tert-butyldimethylsilyl-β-d-glucopyranose were in the 1C4 form. These findings indicate that the introduction of bulky silyl protecting groups at the 2- and 3-positions can flip a pyranose ring into the axial-rich chair form. Previous such ring inversions have been carried out by the silyl protections at the 3- and 4-positions. 相似文献
667.
The formation process of LiNbO3 in the system Li2CO3Nb2O5 was discussed from the results of non-isothermal or isothermal TG experiments and X-ray analysis. The mixture Li2CO3 and Nb2O5 in mole ratios of 1:3, 1:1 or 3:1 was heated at a rate of 5°C min?1 or at various temperatures fixed in the range 475 to 677°C. If the system has a composition of Li2CO3 + 3Nb2O5 or 3Li2CO3 + Nb2O5, the reaction between Li2CO3 and Nb2O5 proceeds with CO2 evolution to form LiNbO3 at ca. 300–600°C, but Nb2O5 or Li2CO3 remains unreacted. A composition of Li2CO3 + Nb2O5 gives LiNbO3 at 300–700°C. The diffusion of Li2O through the layer of LiNbO3 is rate-controlling with an activation energy of 51 kcal mol?1. The reaction between LiNbO3 and Nb2O5 gives LiNb3O8 at 600–700°C. At 700–800°C, a slight formation of Li3NbO4 occurs by the reaction between LiNbO3 and Li2O at the outer surface of LiNbO3 and the Li2O component of Li3NbO4 diffuses toward the boundary of the LiNb3O8 layer through the LiNbO3 layer. The single phase of LiNbO3 is formed above 850°C. 相似文献
668.
Takaaki Horaguchi Kohei Hasegawa Eietsu Hasegawa Takahachi Shimizu Kiyoshi Tanemura Tsuneo Suzuki 《Journal of heterocyclic chemistry》1992,29(2):503-509
Thiopyrano[4,3,2-cd]benzofuran 9 possessing benzofuran and methylenethiopyran structures in the molecule was synthesized starting from 1-chloro-4-methoxy-2-nitrobenzene 11. Some reactions (formylation, protonation and catalytic hydrogenation) on 9 were examined. The 2-position of 9 was highly reactive toward electrophilic reagents and the furan ring was readily reduced by catalytic hydrogenation with palladium-charcoal. Thiopyrano[4,3,2-cd]benzofuran 9 has both properties of methylenethiopyran and benzofuran. 相似文献
669.
Imahori H Kimura M Hosomizu K Sato T Ahn TK Kim SK Kim D Nishimura Y Yamazaki I Araki Y Ito O Fukuzumi S 《Chemistry (Weinheim an der Bergstrasse, Germany)》2004,10(20):5111-5122
Systematic series of indium tin oxide (ITO) electrodes modified covalently with self-assembled monolayers (SAMs) of ferrocene-porphyrin-fullerene triads and porphyrin-fullerene dyads were designed to gain valuable insight into the development of molecular photovoltaic devices. The structures of SAMs on ITO have been investigated by UV/Vis absorption spectroscopy, atomic force microscopy, and cyclic voltammetry. The photoelectrochemical and photophysical (fluorescence lifetime and time-resolved transient absorption) properties were also determined. The highest quantum yield of photocurrent generation (11 %) among donor-acceptor linked systems which are covalently attached to the surface of ITO electrodes was achieved with SAMs of ferrocene-zinc porphyrin-fullerene linked triad on ITO electrodes. The quantum yields of photocurrent generation correlate well with the charge-separation efficiency and the lifetime of the charge-separated state of the porphyrin-fullerene linked systems in solution. These results provide valuable information for the construction of photonic molecular devices and artificial photosynthetic systems on ITO electrodes. 相似文献
670.
Nagahara T Imura K Okamoto H Oguro A Imahori H 《The journal of physical chemistry. B》2005,109(42):19839-19844
We fabricated porphyrin thin films on mica surfaces from acidic aqueous solutions of the preorganized H-aggregates of amphiphilic porphyrins by the simple spin-coating method. The morphological and spectroscopic properties of the film were investigated by scanning near-field optical microscopy. The results obtained in this study demonstrate that the preorganized structure in solution can be transferred as a thin film with a thickness of the monolayer level without losing their substantial structure and photophysical properties. 相似文献