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791.
Rates of inactivation of a five-strain mixture of green fluorescent protein-labeled Escherichia coli O157:H7 in autoclaved and unautoclaved commercial cow manure compost with a moisture content of ca. 38% were determined at temperatures of 50, 55, 60, 65, and 70 degrees C. Trypticase soy agar with ampicillin was determined to be the best medium for the enumeration of heat-injured and uninjured cells of green fluorescent protein-labeled E. coli O157:H7. The results obtained in this study revealed that in autoclaved compost, E. coli O157:H7 reductions of ca. 4 log CFU/g occurred within 8 h, 3 h, 15 min, 2 min, and < 1 min at 50, 55, 60, 65, and 70 degrees C, respectively. At 65 and 70 degrees C, considerably less time was required to kill the pathogen in unautoclaved compost than in autoclaved compost. Decimal reduction times (D-values) for autoclaved compost at 50, 55, 60, 65, and 70 degrees C were 137, 50.3, 4.1, 1.8, and 0.93 min, respectively, and D-values for unautoclaved compost at 50, 55, and 60 degrees C were 135, 35.4, and 3.9 min, respectively. Considerable tailing was observed for inactivation curves, especially at 60, 65, and 70 degrees C. These results are useful for identifying composting conditions that will reduce the risk of the transmission of E. coli O157:H7 to foods produced in the presence of animal fecal waste. 相似文献
792.
Johnson AL Ratajczak C Haugen MJ Liu HK Woods DC 《Reproduction (Cambridge, England)》2007,133(3):609-616
Tumor necrosis factor-related apoptosis inducing ligand (TRAIL) represents one of several cytokine members of the tumor necrosis factor superfamily reported to initiate apoptosis in a wide range of transformed, but not most normal, cell types. The present studies were conducted to evaluate the potential for TRAIL to promote apoptotic cell death in differentiated granulosa cells collected from hen preovulatory follicles. While mRNA encoding critical components (including TRAIL) required for a functional extrinsic cell death pathway are expressed in granulosa cells, TRAIL treatment by itself fails to induce either caspase-3 activity or a decrease in cell viability. On the other hand, preculture of cells with the conventional chemotherapeutic, cisplatin, or the 20S proteosome inhibitor, Z-LLF-CHO, sensitizes granulosa cells to TRAIL as evidenced by enhanced caspase-3 activity after 4 h of culture and loss of cell viability after 24 h when compared with either cisplatin or Z-LLF-CHO treatment alone. Moreover, the sensitizing effect of Z-LLF-CHO on TRAIL-induced loss of cell viability is prevented by the selective caspase-8 inhibitor, Z-IETD-FMK. Interestingly, TRAIL mRNA expression is elevated both in prehierarchal follicles undergoing spontaneous atresia and in prehierarchal follicles induced to undergo atresia for 6 h in vitro. In summary, the data demonstrate the presence of a functional TRAIL signaling pathway in hen granulosa cells, and are consistent with the possibility that TRAIL signaling may directly or indirectly participate in the process of follicle atresia in vivo. 相似文献
793.
E.E. Duarte-Gómez D. Graham M. Budzik B. Paxson L. Csonka M. Morgan B. Applegate M.F. San Martín-González 《LWT》2014
The mechanism that leads to microbial inactivation by high hydrostatic pressure remains elusive. In this study, a high-pressure system interfaced with a photomultiplier tube (PMT) was developed to monitor cellular metabolism in situ using bioluminescent bacterial strains. Preliminary characterization of the system was performed using Pseudomonas fluorescens 5RL expressing lux proteins from Vibrio fischeri. Stepwise increases in pressure at 34 MPa and above resulted in decreased bioluminescence. Square wave exposure to pressures of 69, 103 and 138 MPa showed bioluminescence reductions greater than 95%, but when cells were returned to ambient pressure bioluminescence returned to 51, 38, and 4% of initial bioluminescence values, respectively. An Escherichia coli strain expressing lux proteins from V. fischeri was constructed to determine whether this reversible effect could be observed in another bacterial genus. Square wave perturbations of 69, 103 and 138 MPa resulted in bioluminescence reductions of about 94% at the highest pressure treatment. Upon decompression, bioluminescence returned to 74, 58 and 30% of the initial bioluminescence values for cells treated at 69, 103 and 138 MPa, respectively. These results suggest that square wave exposure to pressure up to 138 MPa induces reversible cell damage in P. fluorescens 5RL and E. coli VF lux. 相似文献
794.
Microbiological effects of acid decontamination of pork carcasses at various locations in processing 总被引:1,自引:0,他引:1
The microbiological effect of hot (55° C), 1% (v/v) lactic acid sprayed on the surface of pork carcasses (n = 36) immediately after dehairing, after evisceration (immediately before chilling) or at both locations in slaughter/ processing was determined. Mean aerobic plate counts (APCs) of all acid-treated carcass surfaces were numerically lower than those of control carcasses: however, in most cases these reductions were not statistically significant (P>0·05). All samples tested for the presence of Salmonella and Listeria were negative. No significant differences in sensory characteristics or microbiological counts were evident for acid-treated and control carcass loins that were vacuum packaged and stored 0–14 days post-fabrication. Mean pH value and scores of sensory attributes such as lean color, surface discoloration, fat color, overall appearance and off-odor of chops from acid-treated carcasses were not significantly and/or consistently different from chops of comparable control carcasses. The role of bacterial attachment to pork skin and its effect on the decontaminating efficiency of lactic acid are discussed. 相似文献
795.
Morgan Allemand Manuel. H. Martin David Reyter Lionel Roué Daniel Guay Carmen Andrei Gianluigi A. Botton 《Electrochimica acta》2011,56(21):7397
This paper presents results on the synthesis of Cu–Pd alloy thin films on Ti substrates by co-electrodeposition of Pd and Cu from nitrate-base electrolytic baths. The deposition rates of Cu and Pd were determined by Electrochemical Quartz Crystal Microbalance as a function of the electrode potential and Cu+2 and Pd+2 concentrations. It is shown that electrodeposition of copper and palladium occurs simultaneously at −0.50 V vs. SCE and that Cu–Pd thin films over the entire composition range were obtained by changing the composition of the solution. X-ray diffraction analyses indicated that these films have a nanocrystalline single-phase face-centered cubic structure and scanning electron microscopy analyses showed that potentiostatically deposited films are rough and porous, which is appropriate for electrocatalysis applications. In an attempt to get denser deposits as required for H2 purification applications, pulsed potential co-electrodeposition was performed and the effect of the deposition conditions on the roughness of the films was assessed by double layer capacitance measurements. It was shown that smooth Cu–Pd films (with Rf value as low as 8, as opposed to more than 120 for films prepared in the potentiostatic mode) could be obtained with a proper choice on the deposition conditions. 相似文献
796.
In this article, we report on the formation of optically transparent photopolymer films from hexanediol diacrylate (HDDA) by inkjet printing, where droplets of monomer approximately 5 μm in diameter were deposited onto a surface. The films were cured by irradiation with a UV‐light‐emitting‐diode light source. It was found that the inkjet‐printed HDDA films picked up a considerable amount of absorbed O2 during printing. Exposure to increasing amounts of O2 during photocuring severely restricted both the degree of conversion and the UV dose required for gelation in proportion to the O2 concentration. Viscoelastic property data indicated that exposure to reduced oxygen concentrations during thermal postcuring (dark reaction) resulted in linear trends of increasing modulus above the glass‐transition temperature (Tg) and increasing Tg itself. Thus, the final crosslink density was greater in fully cured samples that were exposed to atmospheres with increasing inert gas concentrations. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 相似文献
797.
A survey was carried out in 1986 for the occurrence of aflatoxin B1 in peanut butters (129 samples) obtained from specialist Health Food outlets. The results showed that 6.2% of the samples exceeded 10 micrograms/kg of aflatoxin, 8% contained between 2.5 and 10 micrograms/kg, and in the remainder (86%) aflatoxin could not be detected at a limit of 2.5 micrograms/kg. These results show a lower contamination by aflatoxin than found in these products in previous surveys (1982-1984). An aflatoxin B1-specific enzyme-linked immunosorbent assay (ELISA) was employed for the first time in these analyses; and to make an assessment of its performance positive aflatoxin results, together with a random selection of those below the ELISA limit of detection, were additionally analysed by conventional extraction and clean-up followed by HPLC. The ELISA technique offered a significant improvement in speed of analysis over conventional approaches, enabling a six-fold increase in sample throughput compared to that required for conventional analysis, together with other advantages. 相似文献
798.
799.
A simple pressure calibrator is described which is suitable for the routine on-line calibration of pressure transducers in automatically recording data-logging systems. The calibrator is based on a beam balance approach, and steps have been taken to ensure the stability of the system and the reproducibility of the results. 相似文献
800.
Hao Liu Mohammed I. Yanli Fan Morgan M. Jin Liu 《Circuits and Systems II: Express Briefs, IEEE Transactions on》2009,56(7):595-599
This brief presents an adaptive equalizer for high-definition-multimedia-interface (HDMI) systems with a new adaptation scheme by comparing the energy ratio in high-frequency and low-frequency bands of the equalized signal with a self-generated energy ratio. The self-generated energy ratio tracks process, voltage, and temperature variations to overcome the problem with preset energy ratio adaptation. Fabricated in 0.5- mum SiGe BiCMOS technology, the adaptive equalizer occupies 0.25 mm2 and consumes 108 mW from 3.3-V voltage supply at 2.25-Gb/s data rate. Measurement results show that it can automatically adapt to up to 10-m HDMI cables, achieving 0.1-UI peak-to-peak jitter in equalized signals. 相似文献