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91.
Dimethylsiloxane-tetramethyl-p-silphenylenesiloxane-dimethylsiloxane (DMS-TMPS-DMS) triblock copolymer was synthesized by employing living anionic polymerization of hexamethylcyclotrisiloxane (D3). Two synthetic methods were carried out for the polymerization. One of those methods was the anionic polymerization of D3 initiated at the silanolate anion which was prepared from the terminal hydroxyl group of silanol-terminated TMPS prepolymer by reaction with n-butyllithium (method 1). The other was the coupling reaction of vinyl-terminated TMPS prepolymer with hydrosilyl-terminated DMS prepolymer obtained from the anionic polymerization of D3 by using diphenylmethylsilanolate anion as initiator (method 2). In method 1, DMS contents of the copolymers ranged from 25.8 to 72.5 wt% and the values agreed with the ratio of D3 to TMPS prepolymer. The weight-average molecular weights ranged from 1.36×104 to 19.4×104 and were close to the predicted values calculated from the of the TMPS prepolymer and the amount of D3 added. In the case of method 2, weight-average molecular weights ranged from 19.5×104 to 24.2×104. The high molecular weight copolymer could thus be obtained by method 2. Intrinsic viscosity values of the triblock copolymers agreed with calculated values obtained by considering the copolymer as a binary mixture of these homopolymers. Differential scanning calorimetry and thermogravimetry were carried out on the triblock copolymers. The equilibrium melting temperatures of each of the copolymers were very close to that of poly-TMPS (160°C). The glass transition temperature and heat of fusion were decreased as the DMS content was increased. The thermogravimetric curves for the copolymers indicated that the thermal stability of the triblock copolymer was intermediate between the DMS and TMPS homopolymers. 相似文献
92.
93.
As previously reported, high surface area microporous carbons with long-range order can be synthesized by using zeolite Y as a template. In this work, an attempt is made to synthesize porous carbon using several other types of zeolites (zeolite β, ZSM-5, mordenite and zeolite L). Special attention is paid to whether the structural regularity of each zeolite can be transferred to the carbon structure as well as with the case of zeolite Y. The carbon filling method was then examined to see which gives the highest regularity to the carbon structure. It has been found that the optimum carbon filling method for zeolite Y is not an optimum one for the other zeolites and the degree of the regularity of long-range ordering in the carbons strongly depends on zeolite type. The order of the regularity in the resultant carbons is zeolite β>>zeolite L>mordenite>ZSM-5. The effect of zeolite type on the regularity is discussed in relation to the size and the shape of the zeolite channels. 相似文献
94.
The CCl4 plasma treatment of polypropylene films was investigated from the viewpoint of hydrophilic surface modification using a contact-angle meter, ATR FTIR spectroscopy, and angular XPS. Hydrophilicity and chemical composition of the CCl4 plasma treatment was effective in hydrophilic modification. The advancing contact angle of water for polypropylene films was decreased from 99° to 81-7° by the CCl4 plasma treatment, and the surface energy increased from 27.2 to 38.9-67.7 mJ/m2 when the discharge current varied from 50 to 150 mA. The CCl4 plasma initiated chlorination, oxidation, and aluminum sputtering reactions. The chlorination of polypropylene films was favorable in a mild CCl4 plasma operated at discharge current of 50 mA. The oxidation and aluminum sputtering reactions were predominant over the chlorination in strong CCl4 plasmas operated at discharge currents of more than 75 mA. The chlorination initiated by the mild CCl4 plasma was restricted near the film surface within 36 Å deep. The regions modified with the strong CCl4 plasma reached inner layers of 36-49 Å deep. Hydrophilicity caused by the CCl4 plasma treatment may be due not only to chlorine functionalities but also to oxygen and aluminum functionalities. © 1993 John Wiley & Sons, Inc. 相似文献
95.
Antioxidant effects of chlorophyll and pheophytin on the autoxidation of oils in the dark. I. Comparison of the inhibitory effects 总被引:1,自引:0,他引:1
Yasushi Endo Richiro Usuki Takashi Kaneda 《Journal of the American Oil Chemists' Society》1985,62(9):1375-1378
The effects of chlorophyll and pheophytin on the autoxidation of oils in the dark were investigated by oven tests. The results
indicated that both chlorophyll and pheophytin show antioxidant activity when methyl linoleate is used as substrate. Furthermore,
chlorophyll retarded the oxidative deterioration of triglycerides in rapeseed and soybean oils at 30 C. Among the four chlorophyll
derivatives (chlorophylls a and b and pheophytins a and b), chlorophyll a showed the strongest antioxidant activity. The antioxidant
effects of chlorophyll and pheophytin depended on the storage temperature and the kinds of oil used as substrate. 相似文献
96.
Toshio Kimura Yoshikatu Okada Takashi Yamaguchi Yuzo Shimada Kazuaki Utsumi 《The Journal of Adhesion》1994,47(1):179-190
Bondability and interfacial reaction between dielectric and insulator layers have been examined to obtain a basic understanding of bonding mechanisms. Lead-containing complex perovskite was used as a dielectric material. Two kinds of glass-ceramics were used as insulator material; lead borosilicate glass containing Al2O3 (insulator A) and the same containing Al2O3 and MgO (insulator B). Dielectric and insulator layers did not bond when insulator A was used. When insulator B was used, however, strong bonding was achieved between the two layers by firing the powder compacts at temperatures between 800° and 1000°C. Addition of MgO to lead borosilicate glass increased the thermal expansion coefficient to that of the dielectric and enhanced the formation of reaction layers, resulting in good bonding. Two reaction layers were identified. The main reaction products were enstatite and bredigite for one layer contacting the dielectric, and enstatite and a compound with the same diffraction pattern as that of faujasite for the other layers contacting insulator B. 相似文献
97.
A distributed multiple server system is designed and implemented with Web-DB based services for distance learning as well as emergency communication. The system has employed multiple servers located in a distributed campus network environment. Each server of the system has multi-core processors. With so-called “server virtualization” technology, some programs are executed in parallel (on the virtual servers) so that such a system can efficiently perform several functions. For example, two or more application services can be performed simultaneously as “cloud services” on the whole system. The system can provide distance learning scheme for educational tool, at the same time it can also support Web-based surveillance facilities for emergency contact. With qualitative and quantitative approach, trial evaluation of system has been performed in some classrooms of distributed campus. And users can obtain some good results from the above evaluation. 相似文献
98.
Praphan?Pinsirodom Yomi?Watanabe Toshihiro?Nagao Akio?Sugihara Takashi?Kobayashi Yuji?ShimadaEmail author 《Journal of the American Oil Chemists' Society》2004,81(6):543-547
Production of MAG by a lipase-catalyzed reaction is known to be effective at low temperature. This phenomenon can be explained
by assuming that synthesized MAG are excluded from the reaction system because MAG, which have low m.p., are solidified at
low temperatures. Consequently, MAG are efficiently accumulated and do not serve as the precursor of DAG. If this hypothesis
is correct, the critical temperature for MAG production, defined as the highest temperature at which DAG synthesis is repressed,
should depend on the m.p. of the MAG. Esterification of FFA with glycerol using Candida rugosa, Rhizopus oryzae, and Penicillium camembertii lipases produced MAG efficiently at low temperatures. However, Candida lipase showed very low esterification activity at high temperatures (>20°C), and Rhizopus lipase produced not only MAG but also DAG even at low temperatures. Meanwhile, P. camembertii lipase catalyzed synthesis of MAG only from FFA and glycerol at low temperatures, although the enzyme catalyzed synthesis
of DAG from MAG in addition to synthesis of MAG at high temperatures. We thus studied the effect of temperature on esterification
of C10−C18 FFA with glycerol using Penicillium lipase as a catalyst and determined the critical temperatures for production of MAG. The critical temperature for production
of each MAG showed a linear correlation with m.p. of the MAG, which supported the hypothesis. In addition, because the m.p.
of MAG are estimated from that of the constituent FA, the optimal temperature for production of MAG can be predicted from
the m.p. of the FFA used as a substrate. 相似文献
99.
Noboru Hashimoto Yasushi Sawada Takashi Bando Hiroyoshi Yoden Shigehito Deki 《Journal of the American Ceramic Society》1991,74(6):1282-1286
AIN powder was synthesized from aluminum polynuclear complexes. Basic aluminum chloride and basic aluminum lactate were used as the aluminum polynuclear complexes. These starting materials and glucose were dissolved in water and mixed homogeneously. AIN powder was obtained by calcining after drying and precalcining at 800°C under nitrogen gas flow. Then excess carbon was removed by firing in air. Nitridation in the system was investigated and compared with that in the alumina–carbon black system. It was found that in our reaction system nitridation began and proceeded at lower calcination temperatures above 1200°C than in the alumina–carbon black system. Using aluminum polynuclear complexes, AIN was synthesized through the nitridation of γ-alumina and produced in a very fine and sharp particle size distribution. 相似文献
100.
This paper presents a new maritime lifesaving multiple-effect solar still design where several extended wicks feed seawater to their evaporating areas by capillary force, and the resulting water vapor diffuses and condenses on facing wicks with the condensate flowing through the wicks into storage bags. A theoretical analysis showed that a temperature drop through diffusion layers between evaporating and condensing wicks slowly increases in the main evaporating areas and rapidly near salt depositions whereas the evaporation rate decreases slowly in the main area and rapidly near salt depositions. These changes are caused by increases in salt concentrations and resulting boiling point elevation. With steady-state transfer analysis, the proposed still is predicted to produce about 15 kg m −2d−1 fresh water on a sunny day of 22 MJm−2d−1 solar radiation, showing a potential to be a maritime lifesaving desalinator. 相似文献