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排序方式: 共有153条查询结果,搜索用时 31 毫秒
1.
J Barrette R Bellwied P Braun-Munzinger WE Cleland T Cormier G Dadusc G David J Dee O Dietzsch M Fatyga SV Greene JV Germani JR Hall TK Hemmick N Herrmann RW Hogue B Hong K Jayananda D Kraus BS Kumar R Lacasse D Lissauer WJ Llope TW Ludlam R Majka SK Mark JT Mitchell M Muthuswamy E O'Brien C Pruneau FS Rotondo da Silva NC J Simon-Gillo U Sonnadara J Stachel H Takai EM Takagui TG Throwe L Waters C Winter D Wolfe CL Woody N Xu Y Zhang Z Zhang C Zou 《Canadian Metallurgical Quarterly》1995,52(5):2679-2683
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A. N. Cleland D. Esteve C. Urbina M. H. Devoret 《Journal of Low Temperature Physics》1993,93(3-4):767-772
We have demonstrated the use of the single electron transistor (SET) as an amplifier for a photodetector operated at 20 mK. The unparalleled low input noise of the SET permits the detection of very small numbers of charge carriers generated in a bulk p-type Si substrate. We present data showing the response of the detector when it is illuminated by extremely low levels of red light (=650 nm). Although we are not able to prove that individual charge carriers are being detected in our system, the magnitude of the detector response and the level of noise in the system are in good agreement with single charge, and therefore single photon, detection. From the dark current noise of 0.06 electron/s, we estimate a noise-equivalent power NEP=2×10–21 W/Hz for infrared light with =30 µm, and from this calculate a detectivity D*=8×1017 cm-Hz/W. 相似文献
4.
V.R. Tarnawski D.J. Cleland S. Corasaniti F. Gori R.H. Mascheroni 《International Journal of Refrigeration》2005,28(6):425
Thermal conductivity models of frozen soils were analyzed and compared with similar models developed for frozen foods. In total, eight thermal conductivity models and 54 model versions were tested against experimental data of 13 meat products in the temperature range from 0 to −40 °C. The model by deVries, with water+ice (wi) as the continuous phase, showed overall the best predictions. The use of wi leads generally to improved predictions in comparison to ice; water as the continuous phase is beneficial only to deVries model, mostly from −1 to −20 °C; fat is advantageous only to meats with high fat content. The results of this work suggest that the more sophisticated way of estimating the thermal conductivity for a disperse phase in the deVries model might be more appropriate than the use of basic multi-phase models (geometric mean, parallel, and series). Overall, relatively small differences in predictions were observed between the best model versions by deVries, Levy, Mascheroni, Maxwell or Gori as applied to frozen meats with low content of fat. These differences could also be generated by uncertainty in meat composition, temperature dependence of thermal conductivity of ice, measurement errors, and limitation of predictive models. 相似文献
5.
Yue Esther L.; Cleland Thomas A.; Pavlis Michelle; Linster Christiane 《Canadian Metallurgical Quarterly》2004,118(1):184
Dopaminergic modulation of cortical activity has been implicated in the formation of reward associations. There is abundant evidence for dopaminergic effects on olfactory processing. Using an olfactory discrimination task, the authors show that D? and D? dopamine receptors can regulate rats' olfactory discrimination capacities and that the effects of receptor activation functionally oppose one another. Injection of either the D? agonist SKF 38393 (10 mg/kg) or the D? antagonist spiperone (0.62 mg/kg) facilitated the discrimination of similar odorants but had no effect on the discrimination of dissimilar odorants, whereas both the D, antagonist SCH 23390 (0.025 mg/kg) and the D? agonist quinpirole (0.2 mg/kg) significantly impaired rats' ability to discriminate similar and dissimilar odorants. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
6.
Weight loss of frozen bread dough under isothermal and fluctuating temperature storage conditions 总被引:1,自引:0,他引:1
Yuthana Phimolsiripol Ubonrat SiripatrawanDonald J. Cleland 《Journal of food engineering》2011,106(2):134-143
Evaporative weight loss from food leads to both loss of saleable weight and quality deterioration so it need to be minimized. The effect of isothermal and fluctuating conditions on frozen dough weight loss was measured and compared with kinetic, physical and artificial neural network (ANN) models. Frozen dough samples were regularly weighed during storage for up to 112 days in loose-fitting plastic bags. The storage temperatures were in the range of −8 to −25 °C with fluctuations of ±0.1 °C (isothermal), ±1, ±3 or ±5 °C about the mean. For each combination of temperature and fluctuation amplitude, the rate of dough weight loss was constant. The rate of weight loss at constant temperature was nearly proportional to water vapour pressure consistent with standard theories for evaporative weight loss from packaged foods but was also accurately fitted by Arrhenius kinetics. Weight loss increased with amplitude of temperature fluctuations. The increase could not be fully explained by either the physic model based on water vapour pressure differences or the kinetic model alone. An ANN model with six neurons in the input layer, six neurons in hidden layers and one neuron in the output layer, achieved a good fit between experimental and predicted data for all trials. However, the ANN model may not be accurate for product, packaging and storage systems different to that studied. 相似文献
7.
Flaxseed, echium, and canola oils contain α-linolenic acid (18∶3n−3, ALA) in a range of concentrations. To examine their effect
on elevating cardiac levels of long-chain n−3 FA, diets based on these n−3-containing vegetable oils were fed to rats for
4 wk. Sunflower oil, which contains little ALA, was a comparator. Despite canola oil having the lowest ALA content of the
three n−3-containing vegetable oils, it was the most potent for elevating DHA (22∶6n−3) levels in rat hearts and plasma. However,
the relative potencies of the dietary oils for elevation of EPA (20∶5n−3) in heart and plasma followed the same rank order
as their ALA content, i.e., flaxseed>echium>canola>sunflower oil. This paradox may be explained by lower ALA intake leading
to decreased competition for Δ6 desaturase activity between ALA and the 24∶5n−3 FA precursor to DHA formation. 相似文献
8.
Durability of concrete can be improved by applying surface treatments. Pore-lining treatments prevent or delay the ingress of water-borne salts while allowing vapour transfer across the concrete surface. The most common pore-liners are silanes and siloxanes; both reported to give good results. One area of concern, however, is variability in effectiveness of the treatment. This variability may be due to inconsistent coverage or extreme drying conditions. With care these can be controlled but another source of variability which is difficult to control is the moisture profile within the concrete at the time of application of the treatment. This paper describes a test programme to assess the sensitivity of three different surface treatments to moisture gradient in the concrete at the time of application of treatment. The test programme included durability parameters such as chloride ingress, corrosion due to chloride ingress, freeze–thaw salt scaling resistance. Water absorption (sorptivity) of treated and untreated concretes was also measured with a non-distructive test technique called Autoclam with the aim of determining if the Autoclam sorptivity test can be used to assess the effectiveness of surface treatments. Using these results it is possible to avoid, or allow for, moisture conditions which would adversely affect the success of a pore-liner. However there are advantages in specifying an expected performance of the surface treatment rather than specifying the conditions in which it must be placed. By this method a treatment would have to achieve a specified value of sorptivity or a specified reduction in sorptivity. Failure to do so would be an objective basis on which to make a decision of whether or not to reject the treatment. The Autoclam is a device capable of measuring sorptivity values down to the range typical of surface treated concrete. The paper assesses if the device can be used to discriminate between acceptable treatment and unsatisfactory treatments. 相似文献
9.
LG Cleland 《Canadian Metallurgical Quarterly》1996,35(11):1041-1042
10.
Electron irradiation experiments on Si and Ge have indicated the creation of highly mobile interstitial atoms that in turn displace substitutional chemical impurity atoms (S) from the lattice; hence, the primary products of irradiation may be lattice vacancies (V) and interstitial chemical impurities (I). Subsequent annealing may then involve some type of interaction between (V) and (I). The relative amount of radiation damage, or ratio of (I) to the remaining substitutional chemical impurity atom concentration (SR), is also expected to be of importance since there may be competition during annealing between (I) and (SR) for the mobile (V). Samples of P, As, Sb, Sb-Ag, and Sb-Au doped n-type Ge of different initial carrier concentrations were irradiated at ~ 295°K with ~ 1.7 Mev electrons to different ratios of (I) to (SR), and electrical property measurements were made at 77°K immediately after irradiation. The results indicate (1) an increase in the apparent rate of removal of conduction electrons for material of higher initial carrier concentration, (2) a difference in the apparent rate of removal for different dopants, (3) a small dependence of the apparent removal rate on the total amount of disorder introduced, and (4) the amount of annealing was not a sensitive function of the ratio of (I) to (SR) for P or Sb-doped material, but was for As-doped material. 相似文献