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101.
102.
The catechins, including epicatechin gallate (ECG), epigallocatechin (EGC), and epigallocatechin gallate (EGCG), and the theaflavins, including theaflavin (TF), theaflavin monogallate (TF-1), and theaflavin digallate (TF-2), were extracted from green tea and black tea, respectively. The 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging ability, superoxide-scavenging efficiency, and lipid oxidation-inhibition ability of the pure compounds listed above as well as epicatechin (EC), carnosol, carnosic acid, and butylated hydroxytoluene (BHT) were investigated.
The DPPH radical-scavenging ability of the catechins was EGCG > ECG > EGC > EC and of the theaflavins was TF-2 > TF-1 > TF. EGCG, ECG, EGC, TF-2, TF-1, and TF showed higher DPPH radical- and superoxide-scavenging abilities than carnosol, carnosic acid, and BHT. EGCG, ECG, EGC, carnosol, and carnosic acid showed higher lipid oxidation-inhibition activity, as measured by the Rancimat method, than BHT and theaflavins. 相似文献
The DPPH radical-scavenging ability of the catechins was EGCG > ECG > EGC > EC and of the theaflavins was TF-2 > TF-1 > TF. EGCG, ECG, EGC, TF-2, TF-1, and TF showed higher DPPH radical- and superoxide-scavenging abilities than carnosol, carnosic acid, and BHT. EGCG, ECG, EGC, carnosol, and carnosic acid showed higher lipid oxidation-inhibition activity, as measured by the Rancimat method, than BHT and theaflavins. 相似文献
103.
Regular frankfurters treated with tofu powder had decreased fat with no significant differences in color, texture, or overall acceptability compared to a control by sensory analysis. Lean frankfurters with tofu powder had lower moisture and color, better texture, and overall acceptability with no flavor differences from controls. Except for fracturability, there were no differences in texture-related parameters by Texture Profile Analysis (TPA) between regular and control frankfurters but treated lean frankfurters had improved texture. Lean pork sausages treated with tofu powder were lower in fat, higher in protein, and moisture with no differences in sensory attributes compared to controls. 相似文献
104.
Both white kidney bean α-amylase inhibitors WKB 858A (MW 42,000) and WKB 858B (MW 20,000) were composed of two subunits as determined by N-terminal amino acid analysis by amino acid sequence, by SDS-PAGE and by separation on a chromatofocusing column in 8 M urea. N-Terminal amino acids for Inhibitor WKB 858A were alanine and glycine, with a sequence of H2N-Ala-Glu-Asn-Ala-Gly-Thr-Tyr–COOH for deglycosylated 9,000 MW peptide and H2N-Gly-Asn–COOH for deglycosylated 12,000 MW peptide. N-Terminal amino acids for Inhibitor WKB 858B were alanine and serine, with a sequence of H2N-Ala-Thr-Glu-Thr-Ser–COOH for the deglycosylated 9,000 MW peptide and H2N-Ser-Ala-Val-Gly-Leu-Asp-Phe-Val-Leu-Val-Pro-Val-Gin-Pro-Glu-Ser-Lys-Gly-Asp-Thr-VaVal-Glu-Phe-Asp–COOH for the deglycosylated 15,000 MW peptide. Chemical modification of 2 of 7 His residues with diethylpyrocarbonate resulted in 26% loss of inhibitory activity. Modification of 1.5 of 7 Trp residues with N-bromosuccinimide gave 60% loss of inhibitory activity. Modification of 2 of 6 Tyr residues with N-acetylimidazole gave 60% loss of inhibitory activity. Modification of 3.6 of 6 Arg residues with p-hydroxyphenylglyoxal gave 64% loss of inhibitor activity. These results indicate the possible importance of one or more His, Trp, Tyr and perhaps Arg residues for inhibitory activity against porcine pancreatic α-amylase. 相似文献
105.
Young Heui Kim Ki Soo Kim Chang Sung Han Hong Chul Yang Sun Hee Park Kang II Ko Soo Hee Lee KI HO Kim Nam Ho Lee Jung MI Kim Kyunghun Son 《International journal of cosmetic science》2007,29(6):487-488
In order to search for new active cosmetic ingredients of natural origin, we screened about 60 plants collected from Jeju Island, which is located in the southernmost part of the Republic of Korea. We investigated their free radical scavenging activity, elastase inhibition activity, and reduction of MMP-1 mRNA expression for the development of anti-aging ingredients as raw materials for use in cosmetics. In the free radical scavenging capacity assay, 12 extracts, including Typha orientalis (seed) and Torreya nucifera (leaf), showed significant free radical scavenging activity (up to SC50 < 30 μg/ml). Among these extracts, Nymphaea tetragona (rhizome) extract showed the highest free radical scavenging activity (SC50 = 4.7 μg/ml). In the anti-elastase inhibition assay, seven extracts, including T. orientalis (seed) and Persicaria hydropiper (whole plant), showed high inhibitory activity (>50% at 100 μg/ml). Among these extracts, P. hydropiper (whole plant) extract showed the highest elastase inhibition activity (IC50 = 46.7 μg/ml). In the MMP-1 expression assay using RT-PCR, T. orientalis (seed), Pyrrosia hastata (root), and Capsicum annum (whole plant) showed slightly lower inhibition activity than EGCG, which was used as a control. Furthermore, four extracts, including P. hydropiper (whole plant), Filipendula glaberrima (root), N. tetragona (root), and Camellia japonica (leaf), completely inhibited the expression of MMP-1 in human fibroblast cells. The results showed that four of the 60 plant extracts may hold potential for use as natural active ingredients for anti-aging cosmetics. 相似文献
106.
Shirui Guo Duoduo Bao Srigokul Upadhyayula Wei Wang Ali B. Guvenc Jennifer R. Kyle Hamed Hosseinibay Krassimir N. Bozhilov Valentine I. Vullev Cengiz S. Ozkan Mihrimah Ozkan 《Advanced functional materials》2013,23(41):5199-5211
Interest in graphene as a two‐dimensional quantum‐well material for energy applications and nanoelectronics has increased exponentially in the last few years. The recent advances in large‐area single‐sheet fabrication of pristine graphene have opened unexplored avenues for expanding from nano‐ to meso‐scale applications. The relatively low level of absorptivity and the short lifetimes of excitons of single‐sheet graphene suggest that it needs to be coupled with light sensitizers in order to explore its feasibility for photonic applications, such as solar‐energy conversion. Red‐emitting CdSe quantum dots are employed for photosensitizing single‐sheet graphene with areas of several square centimeters. Pyridine coating of the quantum dots not only enhances their adhesion to the graphene surface, but also provides good electronic coupling between the CdSe and the two‐dimensional carbon allotrope. Illumination of the quantum dots led to injection of n‐carrier in the graphene phase. Time‐resolved spectroscopy reveals three modes of photoinduced electron transfer between the quantum dots and the graphene occurring in the femtosecond and picosecond time‐domains. Transient absorption spectra provide evidence for photoinduced hole‐shift from the CdSe to the pyridine ligands, thereby polarizing the surface of the quantum dots. That is, photoinduced electrical polarization, which favors the simultaneous electron transfer from the CdSe to the graphene phase. These mechanistic insights into the photoinduced interfacial charge transfer have a promising potential to serve as guidelines for the design and development of composites of graphene and inorganic nanomaterials for solar‐energy conversion applications. 相似文献
107.
A simple and accurate model of a permanent magnet synchronous motor (PMSM) with a light load is presented in this paper. The light-load condition is always needed in integrated circuit manufacturing machines in order to achieve a fast, accurate and minimum overshoot response. The model proposed here can help a designer to specify the controller's specifications and also to verify the hardware of motor drives. The differential equations of the PMSM are handled by the macromodels in PSPICETM. Moreover, it is revealed that the PMSM system is operating in a 4-state mode rather than a 2-state mode. Experimental results are provided to verify the simulation results of this model. The heavy load condition is also simulated. 相似文献
108.
FAT DUEN HO 《International Journal of Electronics》2013,100(2):327-342
It is important to study an exponential-constant p-n junction because it gives a realistic approximation for many diffused p-n junction profiles. To calculate the space-charge layer capacitance for this junction we use an abrupt space-charge edge approximation with a correction which includes the effect of the mobile carriers at the edges of the space-charge region. In this approach the offset voltage voff is used in place of the built-in potential as obtained from the depletion approximation. An analytical model for the space-charge region capacitance for an exponential-constant junction is developed. This model holds well for zero bias, for small forward voltages, and for reverse voltages. It shows good agreement when compared with the Chawla-Gummel model. It is simple and gives a direct relationship between the depletion capacitance and the applied voltage. 相似文献
109.
DONG‐KYU KIM WON‐WOONG PARK HO WON LEE SEONG‐HOON KANG YONG‐TAEK IM 《Journal of microscopy》2013,252(3):204-216
In this study, a rigorous methodology for quantifying recrystallization kinetics by electron backscatter diffraction is proposed in order to reduce errors associated with the operator's skill. An adaptive criterion to determine adjustable grain orientation spread depending on the recrystallization stage is proposed to better identify the recrystallized grains in the partially recrystallized microstructure. The proposed method was applied in characterizing the microstructure evolution during annealing of interstitial‐free steel cold rolled to low and high true strain levels of 0.7 and 1.6, respectively. The recrystallization kinetics determined by the proposed method was found to be consistent with the standard method of Vickers microhardness. The application of the proposed method to the overall recrystallization stages showed that it can be used for the rigorous characterization of progressive microstructure evolution, especially for the severely deformed material. 相似文献
110.
Tea contains antioxidant compounds, such as (-)-epicatechin (EC), (-)-epigallocatechin (EGC), (-)-epicatechin gallate (ECG), (-)-epigallocatechin gallate (EGCG), gallic acid and caffeine. The antioxidant activity of these compounds as well as 1,3,7-trimethyluric acid (the major metabolite of caffeine) was evaluated using the 2,2-diphenyl-1-picrylhydrazyl radical (DPPH). The antiradical ability according to the EC50 was EGCG > ECG > EGC > gallic acid > EC > BHT > 1,3,7-trimethyluric acid > caffeine. The time for these compounds to reach the steady state was considered, and the concept of antioxidant efficiency (AE50 ) involving the EC50 and the time to reach the steady state was used to evaluate the antiradical efficacy. The order of antiradical efficiency according to AE50 was ECG gallic acid > EGCG > EC > EGC > BHT > 1,3,7-trimethyluric acid > caffeine. 相似文献