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21.
The Fourier transform infrared (FTIR) technique in combination with multivariate data evaluation was used to analyze a wide
variety of cocoa butters (CB), cocoa butter equivalents (CBE), and mixtures thereof. The sample set consisted of 14 CB (10
pure from various geographical origins and 4 commercial mixtures), 18 CBE (12 mixtures and 6 pure CBE from kokum, illipé,
and palm midfraction), and 154 mixtures of CB with CBE at various concentrations (ranging from 5 to 20%). A total of 192 samples
were analyzed in triplicate. All CB and CBE were shown to have very characteristic FTIR spectra that gave highly reproducible
fingerprints. The main vibrational modes were also elucidated. FTIR can easily be employed to distinguish between pure CB
and pure CBE. With prior knowledge of which cocoa butter is present in mixtures, FTIR can be applied to distinguish between
CB mixed with CBE at the 10 and 20% levels (corresponding to about 2 and 5% of CBE in chocolate). However, the study revealed
that a single “global” statistical model (multilayer perceptron, radial basis functions, or partial least square regression)
was not able to predict the precise level of addition. The FTIR approach detailed here shows great potential as a rapid screening
method for distinguishing between pure vegetable fats and, we believe, could be extended to investigate mixtures of CB and
CBE by the establishment of a database. 相似文献
22.
首先对国外的CBE教学模式和双元制教学模式进行了介绍,并进一步结合当前国内的电力培训现状,对当前的电力培训模式提出了改进建议. 相似文献
23.
崔奎勇 《数字社区&智能家居》2007,1(5):1464-1465
高等职业院校培养的是高技能人才,教学内容和方法直接影响着高技能人才培养的质量,如何采用一套简单易用有效的办法来开发教学内容,长期以来一直困扰着广大教师。本文介绍了CBE/DACUM的基本知识,并采用CBE/DACUM的理论和方法对微机组装与维护课程技能教学进行了研究,详细介绍了课程开发的每一步骤,对高职院校各课程教学内容的开发均有一定借鉴作用。 相似文献
24.
阐述了质量与质量教育的重要性,分析了质量教育的任务、形式和现状,探讨了在质量教育中引入实际能力的教育(CBE)的必要性,介绍了CBE的实施方法。 相似文献
25.
乌桕脂真空结晶制取类可可脂及晶型初步研究 总被引:1,自引:1,他引:0
研究用乌桕脂制取类可可脂的新方法和产品的物理化学性能及其初步晶型结构。结果表明 :精炼乌桕脂在真空条件下于 3 7℃保温 2 3h制取的类可可脂产率为 70 %以上 ,且晶型大 ,易分离 ;调温后类可可脂结晶细腻 ,白色无异味 ,口感良好 ,质硬而脆 ,熔点 3 8℃ ,SFC值 2 0℃ ,89 4 % ;3 0℃ ,65 3 2 % ;3 7℃ ,4 62 % ;4 0℃ ,0 4 3 %。X 射线衍射和显微照相表明 :常温 2 5℃ ,结晶 2h ,形成假 β′晶型 ,3 0℃结晶 1d ,5℃结晶 1 6周为 β和 β′混晶 相似文献
26.
任务驱动教学模式和CBE教学模式已被运用在一些课程教学中,并取得了一定的效果。从理论上分析任务驱动教学模式和CBE教学模式的内涵,探索基于任务驱动和CBE相融合的教学模式在《单元电气控制电路》课程中应用的可行性。 相似文献
27.
RTH Rongen M. R. Leys P. J. Van Hall C. M. Van Es H. Vonk J. H. Wolter 《Journal of Electronic Materials》1995,24(10):1391-1398
In this paper, we present a systematic study of the properties of indium phosphide (InP) layers grown by chemical beam epitaxy
(CBE). Trimethylindium (TMIn) and phosphine (PH3) are used as source materials. The relation between the phosphine cracker temperature and the cracking efficiency has been
studied by mass spectroscopy during growth. The growth rate and morphology of the layers have been studied by varying the
TMIn and phosphine flow rates as well as the substrate temperature. We have found that, under a wide range of growth conditions,
the deposition rate is only determined by and proportional to the TMIn flow rate. This is in agreement with literature. Additionally,
we observe that the growth rate decreases below a certain phosphine to TMIn flow rate (V/III) ratio and becomes phosphine
flow limited. From investigations of the growth rate as a function of temperature, it is concluded that the desorption of
indium species from InP starts at a temperature slightly below 540°C. For this desorption process, we have found an activation
energy of (217 ± 20) kJ/mol. Further characterization of the InP layers has been carried out by photoluminescence and Hall
measurements. From both methods, the optimum growth conditions have been established. Under these conditions, we reproduc-ibly
obtain InP layers showing linewidths of the donor-bound exciton transition at 5K around 0.25 meV and a mobility at 77K of
about 7.0·104 cm2/Vs. From the analysis of the mobility in the temperature range from 20 to 300K, we conclude that, additionally to shallow
donors and acceptors, deep-donor centers with an activation energy of about 150 meV are present in all layers. 相似文献
28.
Dong H. K. Li N. Y. Tu C. W. Geva M. Mitchel W. C. 《Journal of Electronic Materials》1995,24(2):69-74
The growth of GaAs by chemical beam epitaxy using triethylgallium and trisdimethylaminoarsenic has been studied. Reflection
high-energy electron diffraction (RHEED) measurements were used to investigate the growth behavior of GaAs over a wide temperature
range of 300–550°C. Both group III- and group Vinduced RHEED intensity oscillations were observed, and actual V/III incorporation
ratios on the substrate surface were established. Thick GaAs epitaxial layers (2–3 μm) were grown at different substrate temperatures
and V/III ratios, and were characterized by the standard van der Pauw-Hall effect measurement and secondary ion mass spectroscopy
analysis. The samples grown at substrate temperatures above 490°C showed n-type conduction, while those grown at substrate
temperatures below 480°C showed p-type conduction. At a substrate temperature between 490 and 510°C and a V/III ratio of about
1.6, the unintentional doping concentration is n ∼2 × 1015 cm−3 with an electron mobility of 5700 cm2/V·s at 300K and 40000 cm2/V·s at 77K. 相似文献
29.
The growth of InxGaj1−xAs (x = 0.13–0.25) on GaAs by chemical beam epitaxy (CBE) and laser-modified CBE using trimethylindium (TMIn), triethylgallium
(TEGa), and tris-dimethylaminoarsenic (TDMAAs) has been studied. Reflection high-energy electron diffraction measurements
were used to investigate the growth behavior of InGaAs at different conditions. X-ray rocking curve and lowtemperature photoluminescence
(PL) measurements were used to characterize the InGaAs/GaAs pseudomorphic strained quantum well structures. Good InGaAs/GaAs
interface and optical property were obtained by optimizing the growth condition. As determined by the x-ray simulation, laser
irradiation during the InGaAs quantum well growth was found to enhance the InGaAs growth rate and reduce the indium composition
in the substrate temperature range studied, 440–500°C, where good interfaces can be achieved. These changes, which are believed
to be caused by laser-enhanced decomposition of TEGa and laser-enhanced desorption of TDMAAs, were found to depend on the
laser power density as well. With laser irradiation, lateral variation of PL exciton peaks was observed, and the PL peaks
became narrower. 相似文献
30.
K. Shiralagi R. Tsui H. Goronkin S. Pendharkar J. Tresek S. Allen 《Journal of Electronic Materials》1998,27(1):L1-L5
We report on a contacting and fabrication scheme for a sub-500 nm InAs/AlSb/GaSb resonant interband tunneling diode (RITD)
without using any fine-line lithography. Epitaxial regrowth on patterned substrates combined with sidewall spacer technology
is used to define the device dimensions. During regrowth, the crystal facet termination obtained by choosing the appropriate
orientation for the device is utilized to make electrical contact to the device in the desired directions and to isolate the
device in all other directions. The concept, fabrication process, current-voltage characteristics of the device, and a comparison
with RITDs fabricated in a conventional manner are reported. 相似文献