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排序方式: 共有1176条查询结果,搜索用时 15 毫秒
961.
Minae Watanabe Jun Ueyama Eiji Ueno Yuko Ueda Masaya Oda Yuko Umemura 《Food additives & contaminants. Part A, Chemistry, analysis, control, exposure & risk assessment》2018,35(7):1316-1323
Dinotefuran is an insecticide belonging to the neonicotinoid class, which is frequently used to control pests in paddy rice owing to its permeability and effectiveness against sucking insects. Since 2002, this insecticide has been commercially available in Japan, and has become controversial due to its high detection frequency in brown rice for primary consumption. In this study, the effects of processing and cooking on the reduction of dinotefuran residues in commercially available brown rice were investigated. Boiled rice is difficult to homogenise and extract with acetonitrile. Using pre-freezing and cryogenic milling with powdered dry ice, dinotefuran in boiled rice was extracted well. A measurement method comprising sample preparation (acetonitrile extraction, gel permeation chromatography, and SPE) and detection with anLC–MS/MS system was used. In 10 out of 25 commercial brown rice samples, dinotefuran was detected at a concentration of 0.04 μg/g (mean), which was more than the limit of quantitation of 0.01 μg/g. The dinotefuran levels were significantly less than the MRL of 2 μg/g in Japan. Even after polishing, washing, and boiling, dinotefuran was detected in 10 brown rice samples, with mean residue levels of 74.7%, 60.8%, and 39.6%, respectively, of the original concentration in brown rice. Based on these data, the processing factor of dinotefuran in boiled rice has been estimated to be approximately 0.4. Dinotefuran residues were reduced in the boiled rice, but less so than other pesticides. Although the maximum daily intake of dinotefuran in boiled rice was 0.0065 mg/person/day, its percent ratio to the ADI of dinotefuran in Japan was less than 0.05%. These results suggest that the daily intake of dinotefuran from rice might not be a critical problem at present, in spite of its relatively high detection frequency in boiled rice. 相似文献
962.
Mikio Taguchi Akira Terakawa Eiji Maruyama Makoto Tanaka 《Progress in Photovoltaics: Research and Applications》2005,13(6):481-488
We have achieved a very high conversion efficiency of 21·5% in HIT cells with a size of 100·3 cm2. One of the most striking features of the HIT cell is its high open‐circuit voltage Voc, in excess of 710 mV. This is due to the excellent surface passivation at the a‐Si/c‐Si heterointerface realized by Sanyo's successful technologies for fabricating high‐quality a‐Si films and solar cells with low plasma damage processes. We have studied ways to treat the surface to produce a good interface throughout our fabrication processes. We have also investigated the deposition conditions of a‐Si layers for optimizing the barrier height for the minority carriers in the heterojunction. Our approach for obtaining HIT cells with a high Voc is reviewed here. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
963.
K Matsushita T Yakushi H Toyama O Adachi H Miyoshi E Tagami K Sakamoto 《Canadian Metallurgical Quarterly》1999,1409(3):154-164
Alcohol dehydrogenase (ADH) of acetic acid bacteria functions as the primary dehydrogenase of the ethanol oxidase respiratory chain, where it donates electrons to ubiquinone. In addition to the reduction of ubiquinone, ADHs of Gluconobacter suboxydans and Acetobacter aceti were shown to have a novel function in the oxidation of ubiquinol. The oxidation activity of ubiquinol was detected as an ubiquinol:ferricyanide oxidoreductase activity, which can be monitored by selected wavelength pairs at 273 and 298 nm with a dual-wavelength spectrophotometer. The ubiquinol oxidation activity of G. suboxydans ADH was shown to be two times higher in 'inactive ADH', whose ubiquinone reductase activity is 10 times lower, than with normal 'active' ADH. No activity could be detected in the isolated subunit II or subunit I/III complex, but activity was detectable in the reconstituted ADH complex. Inactive and active ADHs exhibited a 2-3-fold difference in their affinity to ubiquinol despite having the same affinity to ubiquinone. Furthermore, the ubiquinol oxidation site in ADH could be distinguished from the ubiquinone reduction site by differences in their sensitivity to ubiquinone-related inhibitors and by their substrate specificity with several ubiquinone analogues. Thus, the results strongly suggest that the reactions occur at different sites. Furthermore, in situ reconstitution experiments showed that ADH is able to accept electrons from ubiquinol present in Escherichia coli membranes, suggesting the ubiquinol oxidation activity of ADH has a physiological function. Thus, ADH of acetic acid bacteria, which has ubiquinone reduction activity, was shown to have a novel ubiquinol oxidation activity, of which the physiological function in the respiratory chain of the organism is also discussed. 相似文献
964.
M Toichi Y Kubota T Murai Y Kamio M Sakihama T Toriuchi T Inakuma A Sengoku K Miyoshi 《Canadian Metallurgical Quarterly》1999,31(2):147-154
Trichoderma harzianum, a soil-borne filamentous fungus, is capable of parasitizing several plant pathogenic fungi. Secretion of lytic enzymes, mainly glucanases and chitinases, is considered the most crucial step of the mycoparasitic process. The lytic enzymes degrade the cell walls of the pathogenic fungi, enabling Trichoderma to utilize both their cell walls and cellular contents for nutrition. We have purified a 110kDa novel extracellular beta-1,3-exoglucanase from T. harzianum, grown with laminarin or in dual cultures with host fungi. The corresponding gene, lam1.3, and its cDNA were isolated and their nucleotide sequences determined. The deduced amino-acid sequence predicted a molecular mass of 110.7kDa of a mature protein excluding a signal peptide. LAM1.3 showed high homology to EXG1, a beta-1,3-exoglucanase of the phytopathogenic fungus Cochliobolus carbonum, and a lower homology to BGN13.1, a beta-1,3-endoglucanase isolated from T. harzianum. However, it contains a unique C-terminal embodying cysteine motifs. The expression of lam1.3 in growth with laminarin, but not with glucose, was found to be a result of differential accumulation of the corresponding mRNA. 相似文献
965.
A new type of absorption refrigeration cycle that is co-driven both by solar energy and electricity was evaluated. The principle of a heat transformer was applied to the absorption refrigeration system to increase its efficiency. In this paper, a thermodynamic model describing the performance of the new cycle was developed and a computer program was written to evaluate its performance. The COP, condenser heat load, the theoretical minimum evaporating temperature and refrigeration capacity for a typical daily load of the system were calculated and compared with those of traditional absorption refrigeration systems. The results show that the new cycle not only overcomes some shortcomings of the traditional absorption cycle with unsteady energy input from a variable source such as solar energy, but also increases the system’s coefficient of performance. 相似文献
966.
Song Chen Satoshi Hayakawa Yuki Shirosaki Eiji Fujii Koji Kawabata Kanji Tsuru Akiyoshi Osaka 《Journal of the American Ceramic Society》2009,92(9):2074-2082
Agglomerated amino-modified silica nanoparticles were prepared from a novel Stöber-like precursor system consisting of aminopropyltriethoxysilane (APTES), tetraethoxysilane (TEOS), ethanol, and water where the molar ratio APTES/TEOS was 0, 0.1, 1.0, and 2.0, and the molar ratio H2 O/-SiOC2 H5 was about 20 to 60, or great excess amounts of H2 O were employed. APTES catalyzed the hydrolysis and condensation of both silanes. 29 Si magic angle spinning nuclear magnetic resonance spectra confirmed that the particles consisted of Qn species (Si(OSi) n (OH)4− n ; n =2, 3, 4) and Tn species (NH2 (CH2 )3 –Si(OSi) n (OH)3− n ; n =2, 3). The APTES content in the precursor solutions controlled the agglomerating spherical particle size and morphology: 0.1 in the ratio APTES/TEOS led to almost independent spheres of 300–400 nm, while the larger ratios 1 and 2 led to ∼250 and ∼150 nm spheres, respectively, that were largely agglomerated and some were fused to look like peanut-shells. When soaked in Kokubo's simulated body fluid, those amino-modified particles deposited apatite. The mechanisms of particle formation and apatite deposition were discussed in terms of an intraparticle hydrated layer. 相似文献
967.
Akinori Ando Jun Ogawa Shigenobu Kishino Taiyo Ito Norifumi Shirasaka Eiji Sakuradani Kenzo Yokozeki Sakayu Shimizu 《Journal of the American Oil Chemists' Society》2009,86(3):227-233
The fatty acid desaturation and elongation reactions catalyzed by Trichoderma sp. 1-OH-2-3 were investigated. This strain converted palmitic acid (16:0) mainly to stearic acid (18:0), and further to
oleic acid (c9-18:1), linoleic acid (c9,c12-18:2), and α-linolenic acid (c9,c12,c15-18:3) through elongation, and Δ9, Δ12, and Δ15 desaturation reactions, respectively. Palmitoleic acid (c9-16:1) and cis-9,cis-12-hexadecadienoic acid were also produced from 16:0 by the strain. This strain converted n-tridecanoic acid (13:0) to cis-9-heptadecenoic acid and further to cis-9,cis-12-heptadecadienoic acid through elongation, and Δ9 and Δ12 desaturation reactions, respectively. trans-Vaccenic acid (t11-18:1) and trans-12-octadecenoic acid (t12-18:1) were desaturated by the strain through Δ9 desaturation. The products derived from t11-18:1 were identified as the conjugated linoleic acids (CLAs) of cis-9,trans-11-octadecadienoic acid and trans-9,trans-11-octadecadienoic acid. The product derived from t12-18:1 was identified as cis-9,trans-12-octadecadienoic acid. cis-6,cis-9-Octadecadienoic acid was desaturated to cis-6,cis-9,cis-12-octadecatrienoic acid by this strain through Δ12 desaturation. The broad substrate specificity of the elongation, and
Δ9 and Δ12 desaturation reactions of the strain is useful for fatty acid biotransformation. 相似文献
968.
M. Nishikawa K. Seki Y. Matsuzawa Y. Minami S. Kawata S. Miyoshi Y. Imai R. Saitoh S. Noda S. Tamura S. Tarui 《Lipids》1984,19(10):777-783
The mechanism by which high doses of estrogen influences lipid metabolism was studied with a microtubular blocking agent.
Castrated male rats received oral injection daily for 14 days of 3 mg hexestrol in olive oil, or oil alone as controls. About
half of the animals in each group were injected intraperitoneally with 4 mg/100 g body weight colchicine 3 hr before they
were killed. Hexestrol treatment caused an accumulation of esterified cholesterol in the liver while it decreased those in
serum. Triglyceride concentrations slightly decreased in the liver but were unaffected in serum. On polyacrylamide-gel disc
electrophoresis, the peaks of high density lipoproteins (HDL) and low density lipoproteins (LDL) were decreased remarkably.
Electron microsopic examination of hepatocytes revealed electron-lucent lipid droplets in the cytoplasm.
After a colchicine treatment of the control animals, concentrations of esterified cholesterol and triglycerides markedly increased
in the liver, while those in serum decreased. Electron microscopic examination of hepatocytes revealed numerous secretory
vesicles filled with nascent VLDL. In hexestrol-treated animals, the colchicine treatment was associated with marked decreases
in serumesterified cholesterol and triglyceride as seen in the controls. However, there were no further increases of esterified
cholesterol in the liver, and the increase of triglycerides was slight. Electron microscopic examination showed less secretory
droplets than in the controls.
These data suggest that very low density lipoproteins (VLDL) synthesis in the liver of hexestrol treated rats was inhibited.
An accumulation of esterified cholesterol with a marked decrease in serum could not be accounted for by the inhibition of
lipoproteins secretion, but rather by their enhanced entry into the liver. 相似文献
969.
970.