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41.
Poompat Rattanatraicharoen Keiko Shintaku Kazuhiro Yamabuki Tsutomu Oishi Kenjiro Onimura 《Polymer》2012,53(13):2567-2573
The novel optically active (S)-4-benzyl-2-(ethynylphenyl)-oxazoline (BnEPhOx) was successfully prepared and polymerized using rhodium catalyst ([Rh(nbd)Cl]2) to obtain the moderate molecular weight poly(phenylacetylene)s bearing chiral oxazoline derivatives with high yields (≥90%). The 1H NMR spectra demonstrated that the resulting polymers had high stereoregular structures. Moreover, the poly(phenylacetylene)s bearing chiral oxazoline exhibited better thermal stability than poly(phenylacetylene). The resulting polymers showed higher absolute values of optical specific rotation than the monomer. The polymers also exhibited intense CD signal in the region of the π-π1 band of the conjugated polyacetylene backbone in chloroform solution. The results of specific rotation and CD spectroscopy indicated that all the polymers adopted higher-order structure with predominantly one-handed screw sense.In addition, the resulting polymers emitted fluorescence under UV irradiation. 相似文献
42.
43.
Chiu HP Grünewald J Hao X Brock A Okach L Uno T Geierstanger BH 《Chembiochem : a European journal of chemical biology》2012,13(3):364-366
Sticky residue: Pyrroline-carboxy-lysine (Pcl) can be readily incorporated into proteins expressed in E. coli and mammalian cells by using the pyrrolysyl tRNA/tRNA synthetase pair. Pcl can be used as a single amino acid purification tag and can be site-specifically modified with functional probes during the elution process. 相似文献
44.
Tsutomu Oishi Kenjiro Onimura Wakako Sumida Tadayuki Koyanagi Hiromori Tsutsumi 《Polymer Bulletin》2002,48(4-5):317-325
Summary
Asymmetric anionic polymerizations of achiral N-diphenylmethylitaconimide (DPII) were performed with chiral ligand — organometal complexes in toluene. The obtained poly(DPII)s
exhibited molecular weights of 1.5 × 103 to 6.3 × 103 and specific rotation between +7.5 to −18.4° (THF). The chirality of polymer was significantly affected by the organometals and chiral ligands.
The poly(DPII) obtained with (4S)-2,2′-(1-ethylpropylidene)bis(4-benzyl-4,5-dihydrooxazole) (Bnbox) / n-butyllithium (n-BuLi) exhibited the highest specific rotation (−18.4°). The optical activities of the poly(DPII)s were attributed to configurational
chirality of the main chain more than conformational chirality, judged from NMR, circular dichroism (CD) and GPC analyses
using UV and polarimetric detectors.
Received: 10 January 2002/ Revised: 12 April 2002/ Accepted: 22 April 2002 相似文献
45.
Selectivity and mechanism for skeletal isomerization of alkanes over typical solid acids and their Pt-promoted catalysts 总被引:2,自引:0,他引:2
Atsuyuki Miyaji Tsuneo Echizen Lianshun Li Tetsuo Suzuki Yusuke Yoshinaga Toshio Okuhara 《Catalysis Today》2002,74(3-4):291-297
Selectivities for skeletal isomerizations of n-butane and n-pentane catalyzed by typical solid acids such as Cs2.5H0.5PW12O40 (Cs2.5), SO42−/ZrO2, WO3/ZrO2, and H-ZSM-5 and their Pt-promoted catalysts were compared. High selectivities for n-butane and low selectivity for n-pentane were observed over Cs2.5 and SO42−/ZrO2, while H-ZSM-5 was much less selective, and WO3/ZrO2 was highly selective for both reactions. The Pt-promoted solid acids were usually selective for these reactions in the presence of H2 except for Pt-H-ZSM-5 for n-butane isomerization. Both the acid strength and pore structure would be factors influencing the selectivity. Mechanism of skeletal isomerization of n-butane was investigated by using 1,4-13C2-n-butane over Cs2.5 and Pt–Cs2.5. It was concluded that n-butane isomerization proceeded mainly via monomolecular pathway with intramolecular rearrangement on Pt–Cs2.5, while it occurred through bimolecular pathway with intermolecular rearrangement on Cs2.5. The higher selectivity on Pt–Cs2.5 would be brought about by the monomolecular mechanism. In the skeletal isomerization of cyclohexane, Pt–Cs2.5/SiO2 was highly active and selective, while Pt–Cs2.5 was less selective. Control in the acid strength of Cs2.5 by the supporting would be responsible for the high selectivity. 相似文献
46.
Fengqiu Tang Tetsuo Uchikoshi Yoshio Sakka 《Journal of the American Ceramic Society》2002,85(9):2161-2165
The rheological behavior and electrophoretic deposition (EPD) of ZnO nanopowder (nano-ZnO) in aqueous media have been described. A cationic polyelectrolyte (polyethylenimine, PEI) was used to disperse and modify the surfaces of the ZnO nanoparticles. The rheological properties of the ZnO aqueous suspension were investigated by measuring the viscosity versus the pH and amount of dispersant. The EPD processing was conducted via cathodic electrodeposition, using stable suspensions with low viscosity, and the depositional behavior was investigated. Bubble-free nano-ZnO deposits with uniform microstructures were successfully obtained, which was an indication of good sintering behavior. 相似文献
47.
Tetsuo Asakura Motohiro Kitaguchi Makoto Demura Harutoshi Sakai Keiichi Komatsu 《应用聚合物科学杂志》1992,46(1):49-53
The enzyme glucose oxidase (GOD) was immobilized on the nonwoven fabrics, which have excellent properties in diffusivity of substrates, mechanical strength, and handling, with Bombyx mori silk fibroin gel. The nonwoven fabrics of silk fibroin, viscose rayon, poly-ethyleneterephthalate, 6-nylon, and polypropylene with activated surface by fluoline treatment were used. The stabilities of GOD to heat or pH changes were much improved by the immobilization as well as the case of the GOD immobilized in the silk fibroin membrane. Among nonwoven fabrics, silk fibroin was the most excellent support material for the immobilization of GOD although all nonwoven fabrics used here are able to be used as the support materials. The increase of the sensitivity was observed when the glucose sensor was made with the GOD immobilized on nonwoven silk fabrics as four times compared with the case of the GOD immobilized in the silk fibroin membrane. 相似文献
48.
Hong Lin Tetsuro Jin riy Dmytruk Tetsuo Yazawa 《Journal of the American Ceramic Society》2003,86(11):1991-1993
A translucent, conductive, porous nanocomposite was designed and prepared by depositing SnO2 on the inner surfaces of the pores of a porous glass plate and on its outer surface using a chemical vapor deposition method. The porous nanocomposite almost maintained its large surface area and pore volume because the pores remained open after they were deposited with SnO2 . Conductivity between the two outer surfaces of the nanocomposite plate was confirmed for the first time. 相似文献
49.
The triad-level sequence analysis of poly(ethylene/1,4-cyclohexanedimethylene terephthalate) copolymer was reported in a solvent system of o-chlorophenol/deuterated chloroform mixture (50/50 v/v) at 80 °C using 600 MHz 1H NMR. The well-resolved alcoholic CH2 proton peak of the glycol units was observed, which made the detailed sequence analysis possible. The peaks of the cis- and trans-forms of the 1,4-cyclohexanedimethylene glycol units were split into the triad sequence in the chain and could be assigned by a comparison of the spectra with those of homopolymers and by an additional two-dimensional heteronuclear multiple bond correlation observation. The triad sequence distributions centered on 1,4-cyclohexanedimethylene glycol units were determined, which was independent of the cis- and trans-forms of the units and controlled according to Bernoullian statistics. 相似文献
50.
Yusaku Takita Jun-ichi Moriyama Hiroyasu Nishiguchi Tatsumi Ishihara Fusakazu Hayano Tetsuo Nakajo 《Catalysis Today》2004,88(3-4):103-109
Activity for hydrolysis of CCl2F2 (CFC12) on various metal sulfate was investigated. Zr(SO4)2 was found to be the most active while FeSO4, Cr2(SO4)3, Al2(SO4)3, La2(SO4)3 and Ce2(SO4)3 had intermediate activity. MnSO4, CoSO4, and MgSO4 showed low activity and SrSO4, CaSO4, and BaSO4 had even less activity. The major carbon containing product was CO2 and small amount of CClF3 and CO were formed over several sulfates. The crystal structure of the sulfates was stable during decomposition of CCl2F2, and the conversion reached a steady state after initial decrease at 275 °C over Zr(SO4)2 catalyst. The concentration of surface hydroxyl was larger than that over AlPO4-based catalysts and a reaction mechanism similar to that over AlPO4-based catalysts was proposed. 相似文献