首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   87篇
  免费   2篇
  国内免费   1篇
电工技术   3篇
综合类   1篇
化学工业   13篇
机械仪表   4篇
建筑科学   2篇
能源动力   1篇
轻工业   51篇
无线电   2篇
一般工业技术   5篇
冶金工业   1篇
自动化技术   7篇
  2022年   2篇
  2021年   2篇
  2018年   1篇
  2014年   1篇
  2013年   17篇
  2012年   3篇
  2011年   4篇
  2010年   3篇
  2009年   2篇
  2008年   2篇
  2006年   2篇
  2003年   1篇
  2002年   3篇
  1999年   1篇
  1998年   1篇
  1997年   4篇
  1996年   2篇
  1995年   1篇
  1994年   1篇
  1993年   10篇
  1991年   3篇
  1990年   4篇
  1989年   1篇
  1988年   1篇
  1987年   2篇
  1986年   1篇
  1985年   3篇
  1984年   1篇
  1983年   4篇
  1982年   1篇
  1981年   3篇
  1980年   1篇
  1978年   1篇
  1974年   1篇
排序方式: 共有90条查询结果,搜索用时 15 毫秒
1.
This paper presents a study of rates of heat transfer to non-Newtonian fluid foods: mango and papaya nectars, passing through horizontal tubes of circular cross section under laminar flow conditions. Determination of the flow and thermal properties of the fluids under study was performed to adequately explain heat transfer experiences. A laminar mixed convection equation was used for describing experimental heat transfer coefficients: Nu = 1.75 [Gz + 0.0083 (Grw . PrW)0.75]1/3 . δ1/3 . (Kb/Kw)0.14 The experimental data covered Graetz numbers between 500 and 7000, and were correlated with a mean deviation of 8.4%. The results should be helpful for interpreting heat transfer to pseudoplastic materials in the design of double tube heat exchangers.  相似文献   
2.
Interactions between the yeast strain used for primary oenological fermentation and the bacterium used to conduct subsequent malolactic fermentation were studied under model winemaking conditions. A commercial Saccharomyces cerevisiae wine yeast (strains, EC 1118, AWRI 835 and CY-3079) was grown in a defined medium whose composition approximated grape juice. Fermentations by all strains reached dryness, and retained a cell viability of greater than 90% upon completion of fermentation. Highest total viable cell number and percentage of viable cells were recorded for EC 1118. A sur lie ageing of the fermented medium over a 12 week period revealed a bi-phasic decay of culture viability for all strains. Thus 99% of cells had died within 2 weeks post-fermentation. Viabilities were then stable for the subsequent 4–6 week period before a second decline phase ensued and ended in either a minimal ( ca 100 CFU/mL, EC 1118) or no viable cells being detected at 12 weeks of ageing. The growth response of an Oenococcus oeni inoculum to yeast culture supernatants, previously aged for up to 12 weeks in the presence or absence of yeast lees, was evaluated in a bio-assay. In this way, yeast strains could be designated as being either inhibitory, neutral or stimulatory to the growth of O. oeni (strain Lc5p). Inhibition by supernatants of strain EC 1118 was evident, but found to be reduced by ageing the supernatant (with or without lees). Conversely, longer ageing on yeast lees increased the magnitude of the stimulatory response in O. oeni (strain Lc5p) to the supernatant from the wine yeast (strain CY-3079).  相似文献   
3.
Bifidobacterium bifidum, Lactobacillus casei, Lactobacillus plantarum, Lactococcus diacetylactis, Leuconostoc mesenteroides, Leuconostoc oenos, Pediococcus pentosaceus and a mixed culture of Propionibacterium shermanii and P. pentosaceus were used to ferment a model low salt (2.5% NaCl) cucumber juice brine at 22–26°C for 39 days. Percent sugar fermented ranged from 16.2 to 87.7. Substrates were citric acid, fructose, glucose and malic acid. Fermentation products quantitated were acetic acid, acetoin, ethanol, lactic acid, mannitol, and propionic acid with percent carbon recovery varying from 71.1 to 101.1. Final pH ranged 3.24 to 4.12. Each fermentation differed quantitatively in substrates and products formed suggesting use of these bacteria as cultures to ferment low salt brined cucumbers and generate a variety of unique organoleptic properties.  相似文献   
4.
The grain-boundary diffusion product, D'δ , of 51Cr in MgO and Cr-doped MgO as a function of grain-boundary orientation and point-defect concentration was determined at T =1200° to 1450°C. A large degree of anisotropy was found in the grain-boundary diffusion behavior in MgO. The ratio of D'δ|| parallel to D'δ perpendicular to the growth direction, D'||/D' , is 102 for a 5° (100) tilt boundary, decreased to ∼2 in boundaries with tilt angles > 10°. The decrease in D'||/D' is due to a large increase in D' with increasing tilt angle. The results indicate that grain-boundary diffusion in MgO is connected to the orientation of dislocations and the mechanism is one of dislocation pipe diffusion. The grain-boundary diffusion product D'δ increases with increasing Cr concentration in MgO and is ∼4 times larger for MgO containing 0.56 at. % Cr than for the undoped MgO. For all bicrystals studied, the activation energies are within 180 ± 20 kJ/mol which is 60% of the activation energy for 51Cr diffusion in undoped MgO.  相似文献   
5.
6.
The phase relations in the systems MgO-Y2O3-ZrO2 and CaO-MgO-ZrO2 were established at 1220° and 1420°C. The system MgO-Y2O3-ZrO2 possesses a much-larger cubic ZrO2 solid solution phase field than the system CaO-MgO-ZrO2 at both temperatures. The ordered δ phase (Zr3Y4O12) was found to be stable in the system ZrO2-Y2O3 at 1220°C. Two ordered phases φ1 (CaZr4O9) and φ2 (Ca6Zr19O44) were stable at 1220°C in the system ZrO2-CaO. At 1420°C no ordered phase appears in either system, in agreement with the previously determined temperature limits of the stability for the δ, φ1, and φ2 phases. The existence of the compound Mg3YzO6 could not be confirmed.  相似文献   
7.
8.
Edible coatings with low potassium sorbate permeability could be used to increase the microbial stability of food surfaces. However, such coatings could induce anaerobic food conditions if their oxygen permeability were low. the oxygen permeability of an edible emulsion film (average thickness, 55 μm), composed of methylcellulose and palmitic acid (weight ratio of 3:1), was evaluated at 24°C, atmospheric pressure, and at different percentages of relative humidity (RH). RH values in the 0–57% range had no significant effect on oxygen transmission rate (OTR); calculated OTR values ranged from 660 to 740 mL O2 (STP)/m2 24h atm. At 79% RH, the OTR doubled to 1,500 mL O2 (STP)/m2 24h atm. This effect correlated well with the moisture isotherm for the film which showed a low moisture content in the 0–57% RH range and a rapid increase at higher RH values. OTR values, particularly at high relative humidity, indicate no risk of developing anaerobic conditions on the food surface.  相似文献   
9.
The prediction of structural performance plays a significant role in damage assessment of glass fiber reinforcement polymer (GFRP) elastic gridshell structures. Machine learning (ML) approaches are implemented in this study, to predict maximum stress and displacement of GFRP elastic gridshell structures. Several ML algorithms, including linear regression (LR), ridge regression (RR), support vector regression (SVR), K-nearest neighbors (KNN), decision tree (DT), random forest (RF), adaptive boosting (AdaBoost), extreme gradient boosting (XGBoost), category boosting (CatBoost), and light gradient boosting machine (LightGBM), are implemented in this study. Output features of structural performance considered in this study are the maximum stress as f1(x) and the maximum displacement to self-weight ratio as f2(x). A comparative study is conducted and the Catboost model presents the highest prediction accuracy. Finally, interpretable ML approaches, including shapely additive explanations (SHAP), partial dependence plot (PDP), and accumulated local effects (ALE), are applied to explain the predictions. SHAP is employed to describe the importance of each variable to structural performance both locally and globally. The results of sensitivity analysis (SA), feature importance of the CatBoost model and SHAP approach indicate the same parameters as the most significant variables for f1(x) and f2(x).  相似文献   
10.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号