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721.
722.
Soybean cake has been shown to be a rich source of isoflavone and can be produced during processing of soybean oil as byproduct. The objectives of this study were to compare the extraction yield of isoflavone from soybean cake by solvent and supercritical carbon dioxide, and study the conversion of isoflavone glucosides to the biologically active aglycone by employing β-glucosidase. Results showed that with supercritical carbon dioxide extraction, a maximum yield of malonylglucoside and glucoside was generated at 60 °C and 350 bar, while a high level of acetylglucoside and aglycone was produced at 80 °C and 350 bar. Supercritical carbon dioxide extraction resulted in a lower yield of total isoflavone than solvent extraction, but the former was more applicable to extraction of acetylglucoside and aglycone, and the latter to malonylglucoside and glucoside. A peak level of aglycone was attained from conversion of isoflavone glucoside by β-glucosidase at 55 °C, pH 5, concentration 50 U/ml and incubation time of 2 h. 相似文献
723.
Julia L. Tetens Steffen Billerbeck Julia A. Schwenker Christina S. Hölzel 《Journal of dairy science》2019,102(12):11449-11452
Antimicrobial residues in milk have been discussed as a possible selector for Enterobacteriaceae that produce extended-spectrum β-lactamases (ESBL) in dairy herds. Such residues are found in waste milk after antibiotic treatment of mastitis, but antibiotic dry cow therapy might also lead to antibiotic residues in colostrum and in milk during early lactation. While it is known that feeding of waste milk selects ESBL bacteria in calves, this was not investigated for colostrum yet, which is supposed to contain much lower antibiotic concentrations than waste milk. In this observational prospective case study on 2 farms, we hypothesized that blanket dry cow treatment with β-lactams would have more selective (here: increasing) effects on ESBL concentrations than selective (here: individually chosen) antibiotic dry cow therapy. Thus, we compared concentrations of ESBL-producing Enterobacteriaceae in feces of calves (n = 50) at 2 dairy farms with different management of antibiotic dry cow therapy. Considerably higher concentrations of ESBL-producing Escherichia coli were observed in blanket antibiotic dry cow therapy on d 3 of the calf's life (7.6 vs. 5.3 log cfu/g of calf feces). Both farms used narrow-spectrum penicillin combined with aminoglycosides for drying off, and the majority of ESBL isolates (93%) were co-resistant to aminoglycosides. No waste milk was fed to calves and no calf was treated with β-lactam antibiotics or aminoglycosides during the first 3 d of life, thus differences were most likely associated with different frequency of antibiotic dry cow therapy on farms (19 of 25 mother cows on farm A, 9 of 25 on farm B). Even though the presumable selection effect of antibiotics used for drying off decreased within the next 3 wk, this result further emphasizes the need for the reduction and prudent use of antibiotic dry cow therapy on farms. 相似文献
724.
Cells of Daniell-type with copper–zinc electrochemical couples and sodium β″-alumina solid electrolyte (BASE) were constructed. The cathode consisted of copper in contact with its ions (Cu/Cu2+) while zinc in contact with its ions (Zn/Zn2+) constituted the anode. Dimethyl sulfoxide (DMSO) containing 1 M NaBF4 was used as the liquid electrolyte. The configuration of the cell constructed can be written as follows:
相似文献
Zn(s)/ZnCl2(DMSO)(0.1 M), NaBF4(1 M)/BASE/NaBF4(1 M), CuCl2(DMSO)(0.1 M)/Cu(s)
725.
以自制的β对-苯基苯甲酰丙酸为原料,经Clemmensen还原得γ-4-联苯丁酸,再用多聚磷酸(PPA)催化羧酸发生分子内酰化反应,得到7-苯基-1-氧代-1,2,3,4-四氢萘。实验结果表明,PPA对于羧酸的分子内Friedel-Crafts反应具有较好的催化作用。 相似文献
726.
研究了脱铝超稳 Y催化苯乙酸与 β 苯乙醇直接酯化反应 ,考察了催化剂硅铝比、催化剂用量、反应物配比、带水剂和反应时间对酯化反应的影响 ,结果表明 ,在最佳反应条件下 ,反应在 4 h内完成转化率达 92 %以上 ,催化剂可重复使用 相似文献
727.
728.
Abstract Horseradish peroxidase–catalyzed dehydrogenative polymerizations of the p-hydroxyphenyl monolignol glucoside (triandrin (1P)) and the syringyl monolignol glucoside (isosyringin (1S)) resulted in the formation of water-soluble lignin-like polymers (DHPs). The polymerization of 1P gave highly polymerized DHPs in high yields as did previously reported polymerization of the guaiacyl monolignol glucoside (isoconiferin (1G)). It was shown that the hydrophilic D-glucose units of 1G and 1P contribute to a marked increase in the molecular weights of the resulting DHPs. On the other hand, the homogeneous phase polymerization of 1S, similar to the polymerization of sinapyl alcohol, gave DHPs with extremely low molecular masses in poor yields. Structural characterization indicated that the DHPs from 1P and 1S were lignin-like polymers containing glucosidic units on their sidechains. It was also confirmed that D-glucosyl units introduced onto the γ-position of monolignols do not significantly affect the electrochemical oxidizability and the kinetics of the HRP-catalyzed initial monomer consumption. 相似文献
729.
Selective photocatalytic oxidation of steroid estrogens in water treatment: urea as co-pollutant 总被引:2,自引:0,他引:2
The objective of the present research concerns the competitive photocatalytic oxidation (PCO) and adsorption of steroid estrogens (SEs) on titanium dioxide in presence of urea. The results showed the indifference of SEs towards the presence of urea in concentrations characteristic for the domestic sewage. The selective PCO of SEs appeared to be feasible in alkaline media, in which the PCO exhibited the highest efficiency. Ethanol used for hydrophobic SEs dissolution in water appeared to be interfering with the PCO. 相似文献
730.
The second-order rate constants (at pH 7, 25 degrees C) for the reduction of three cationic triarylmethane dyes [pararosaniline (PR+), malachite green (MG+), methyl green (MeG+)] by NADH were 1.4 x 10(-2) to 6.7 x 10(-2)mM(-1)min(-1). Based on these values the intracellular nonenzymatic reduction of TAM+ to TAM-H by endogenous NADH was estimated to proceed with an average half-life of 30 min. Rapid and significant adduct formation was observed with the thiol, 3-mercaptopropionic acid (MPA), suggesting that the primary intracellular form of the dyes must be a thiol adduct and that the conversion to adduct form takes place within ms-s. These time frames, when compared to the min-h time frame for microbial clearance of triarylmethanes from culture media, suggest that transport must be the rate-limiting step in non-adsorptive (chemical) clearance of the dyes and that the presence of enzymes to complement the nonenzymatic reductive and adduct-forming activities cited serves a kinetically limited purpose. It appears that a superior catalytic scavenger will be one with a superior transport capacity. 相似文献