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111.
Enrique Del Castillo Douglas C. Montgomery 《Quality and Reliability Engineering International》1996,12(3):157-157
The first two tables in Reference 1 are incorrect. Corrected tables are provided below. The errors do not affect the conclusions or the discussion in that paper. 相似文献
112.
113.
Formation of pesticide nonextractable (bound) residues in soil: magnitude, controlling factors and reversibility 总被引:1,自引:0,他引:1
The analysis of the coherent data on nonextractable (bound) residues (NER) from the literature and EU pesticide registration dossiers allows the identification of general trends, in spite of the large variability and heterogeneity of data. About 50% of the pesticides reviewed exhibit a low proportion of NER (less than 30% of the initial amount) while only 12% of pesticides have a proportion of NER exceeding 70%. The lowest proportion of NER was found for dinitroanilines (<20%), and the largest value was obtained for carbamates, and in particular dithiocarbamates. The presence of chemical reactive groups, such as aniline or phenol, tends to yield a larger proportion of NER. NER originating from N-heteroatomic ring were found to be lower than those from phenyl-ring structures. Among the environmental factors affecting the formation of NER, microbial activity has a direct and significant effect. Concerning the NER uptake or their bioavailability, consistent data suggest that only a small percentage of the total amounts of NER can be released. The analysis of NER formation kinetics showed that incubation experiments are often stopped too early to allow a correct evaluation of the NER maturation phase. Therefore, there is a need for longer term experiments to evaluate the tail of the NER formation kinetics. Still, the heterogeneity of the NER data between pesticides and for specific pesticides calls for great care in the interpretation of the data and their generalization. 相似文献
114.
Mora A León SL Blanco M Blanco JE López C Dahbi G Echeita A González EA Blanco J 《International journal of food microbiology》2007,114(2):204-210
The present study was conducted in Lima Metropolitana to evaluate the prevalence of Shiga toxin-producing Escherichia coli (STEC) O157:H7 in raw beef, raw ground beef, soft cheese and fresh vegetables, sampled at different markets in the city. Between October 2000 and February 2001, 407 food samples were collected from different markets in the 42 districts of Lima Metropolitana. Samples were assayed for E. coli O157 by selective enrichment in modified Tryptic Soy Broth containing novobiocin, followed by immunomagnetic separation (IMS) and plating onto sorbitol MacConkey agar supplemented with cefixime and potassium tellurite. Fifty (12.3%) of 407 food samples resulted positive for E. coli O157 isolation (23 of 102 ground beef; 15 of 102 beef meat; eight of 102 soft cheese and four of 101 fresh vegetables). Thirty-five E. coli O157 isolates were further analysed for the presence of virulence genes. All 35 were positive by PCR for O157 rfbE, fliCh7, eae-gamma1 and ehxA genes. In addition, genes encoding Shiga toxins were detected in 33 of 35 isolates, five isolates (14%) encoded stx(1), stx(2), and 28 (80%) stx2 only. The isolates were of seven different phage types (PT4, PT8, PT14, PT21, PT34, PT54, and PT87) with three phage types accounting for 80% of isolates: PT4 (15 isolates), PT14 (8 isolates), and PT21 (5 isolates). Interestingly, the majority (31 of 35; 89%) of E. coli O157:H7 isolates characterized in this study belonged mainly to the phage types previously found in STEC O157:H7 strains associated with severe human disease in Europe and Canada. Pulsed-field gel electrophoresis (PFGE) of 32 isolates revealed 14 XbaI-PFGE groups (I to XIV) of similarity >85%, with 23 (72%) isolates grouped in five clusters. Some isolates from different districts presented a high clonal relatedness. Thus, PFGE group VIII clustered eleven strains from nine different districts. The broad range of PFGE subtypes found in this study demonstrates the natural occurrence of many genetic variants among STEC O157:H7 spread in Lima. 相似文献
115.
Concepción Vidal-Valverde M. Carmen Martin-Villa Josefa Herranz Enrique Rojas-Hidalgo 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1981,172(2):93-95
Summary The sugar content of fourteen soft drinks amply consumed in Spain has been determined by high performance liquid chromatography (HPLC). The method, fast and reliable requires a minimum of sample preparation. For the total sugar content, a comparison is made with the classical column chromatography.
Bestimmung von Kohlenhydraten in Erfrischungsgetränken durch Hochdruckflüssigkeitschromatographie
Zusammenfassung Der Zuckergehalt von vierzehn Erfrischungsgetränken, deren Verbrauch in Spanien sehr groß ist, wurde durch die Hochdruckflüssigkeitschromatographie (HPLC) festgestellt. Diese schnelle und zuverlässige Methode erfordert ein Minimum an Vorbereitungen. Für den gesamten Zuckergehalt wird ein Vergleich mit der klassischen Säulenchromatographie durchgeführt.相似文献
116.
The rates of CO and CO/CO2 hydrogenation at 4.2 MPa and 523 K are reported for a series of Cu/SiO2 catalysts containing 2 to 88 wt.% Cu. These catalysts were prepared on a variety of silica sources using several different Cu deposition techniques. In CO/CO2 hydrogenation, the rate of methanol formation is proportional to the exposed Cu surface area of the reduced catalyst precursor, as determined by N2O frontal chromatography. The observed rate, 4.2×10–3 mole CH3OH/Cu site-sec, is within a factor of three of the rates reported by others over Cu/ZnO and Cu/ZnO/Al2O3 catalysts under comparable conditions. These results suggest that the ZnO component is only a moderate promoter in methanol synthesis. Hydrogenation of CO over these catalysts also gives methanol with high selectivity, but the synthesis rate is not proportional to the Cu surface area. This implies that another type of site, either alone or in cooperation with Cu, is involved in the synthesis of methanol from CO. 相似文献
117.
J. Requies M. B. Güemez A. Iriondo V. L. Barrio J. F. Cambra P. L. Arias 《Catalysis Letters》2012,142(1):50-59
Abstract
n-Butanol dehydrogenation to butyraldehyde was studied using Ru, Cu and Ru–Cu catalysts supported on ceria, titania and zirconia. Among the monometallic Cu and Ru supported catalysts, the non-noble catalytic systems recorded higher conversions and butyraldehyde selectivities than the noble catalysts. Furthermore, the 5Cu/ZrO2 catalyst had the best catalytic activity and selectivity. This behaviour is related to the good metal phase dispersion on the zirconia structure. The addition of Ru reduced this catalyst’s performance because Ru incorporation weakened the Cu-support interaction and favoured the sintering of the Cu metal crystallites. 相似文献118.
119.
The effect of probiotic cultures over Listeria monocytogenes and Escherichia coli O157:H7 during yogurt storage was evaluated. Two different yogurt brands, one with additional probiotic cultures (Lactobacillus casei and L. acidophilus) were inoculated with known populations (106 UFC/g) of either L. monocytogenes or E. coli O157:H7 in three different times and stored for 32 days at 5 degrees C. Every four days the count of lactic bacteria, the added pathogens and pH was evaluated, according to the methodology described in the Bacteriological Analytical Manual. The pH and lactic bacteria population were constant during the testing period. Yogurt with additional probiotic cultures reduced the population of L. monocytogenes in 8 days, the population of E. coli O157:H7 in 16; yogurt with no additional probiotics took 20 days to reduce L. monocytogenes to non-detectable levels and even after 28 days of storage, E. coli O157:H7 was cultured. In this work, the beneficial effects of additional probiotic cultures in yogurt is confirmed again. 相似文献
120.
Boron dilution effect on boiling heat transfer with special reference to nuclear reactors technology
The collateral-effect of the boron dilution in nuclear reactors and its significance with regard boiling heat transfer is discussed. Utilizing a simplified model, an analytical expression for the boiling heat transfer as function of boric acid concentration was derived. The above equation agree with the available experimental measurements made on zircalloy-4. 相似文献