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排序方式: 共有105条查询结果,搜索用时 15 毫秒
1.
Yuelong Ma Le Zhang Tianyuan Zhou Bingheng Sun Chen Hou Shunshun Yang Jin Huang Rui Wang Farida A. Selim Zhongying Wang Ming Li Hao Chen Yun Wang 《Journal of the European Ceramic Society》2021,41(4):2834-2846
Ce:Y3Al5O12 transparent ceramics (TCs) with appropriate emission light proportion and high thermal stability are significant to construct white light emitting diode devices with excellent chromaticity parameters. In this work, strategies of controlling crystal-field splitting around Ce3+ ion and doping orange-red emitting ion, were adopted to fabricate Ce:(Y,Tb)3(Al,Mn)5O12 TCs via vacuum sintering technique. Notably, 85.4 % of the room-temperature luminescence intensity of the TC was retained at 150 °C, and the color rendering index was as high as 79.8. Furthermore, a 12 nm red shift and a 16.2 % increase of full width at half maximum were achieved owing to the synergistic effects of Tb3+ and Mn2+ ions. By combining TCs with a 460 nm blue chip, a warm white light with a low correlated color temperature of 4155 K was acquired. Meanwhile, the action mechanism of Tb3+ ion and the energy transfer between Ce3+ and Mn2+ ions were verified in prepared TCs. 相似文献
2.
Daniel Escolar María R. Haro Jesús Ayuso 《Journal of the American Oil Chemists' Society》2002,79(8):769-774
Four polynomial expressions are obtained that provide a good approximation and an easy, rapid calculation of the chromatic
coordinates and the chroma—L
*, a
*, b
*, and C—for the illuminant C and the standard observer, for a virgin or extra virgin olive oil; absorbance is measured at only 480
and 670 nm. These are as follows: L
*=0.556458(A480)2−2.51145A480+0.55504(A670)2−8.53016A670+98.4089; a
*=0.177372(A480)2+2.1363A480+1.43254(A670)2−0.789231A670−13.9246; b
*=−16.0277(A480)2+79.8932A480−5.06558(A670)2+3.36169A670+31.9405; C=−15.8439(A480)2+78.9312A480−5.26784(A670)2+3.56917A670+33.3927. These give acceptable results, making the method a practical alternative to the extremely laborious Commission Internationale
d’Eclairage (CIE) L
*
a
*
b
*
system, by which 391 absorbance values must be measured individually, nanometer by nanometer, before applying more complex
equations. The validity of the proposed method has been confirmed by comparison, using a set of 20 sample oils different from
the set of 25 oils used to generate the order of the equations. The variations between the values provided by the proposed
and standard methods, respectively, had a mean of 0.00 for each of the chromatic variables—L
*
, a
*
, b
*
, and C; SD were moderate (0.71, 0.52, 1.22, and 1.22, respectively); the root mean square and the R
2-terms also confirmed the validity of the method. 相似文献
3.
Berta Gonçalves Ana Paula Silva José Moutinho-Pereira Eunice Bacelar Eduardo Rosa Anne S. Meyer 《Food chemistry》2007,103(3):976-984
The relationship between colour parameters and anthocyanins of four sweet cherry cultivars, Burlat, Saco, Summit and Van was studied. The colour (L∗, a∗, b∗, chroma and hue angle parameters) and anthocyanins were analysed during two different years at two different ripening stages (partially ripe, and ripe, respectively). The cherries were analysed at harvest and after storage at 1.5 ± 0.5 °C and 15 ± 5 °C for 30 and 6 days, respectively. The colour was measured by tristimulus colourimetry (CIELAB system) directly on the fruits, while anthocyanins were quantified by HPLC-DAD analysis on methanolic extracts of freeze-dried samples of the fresh cherries and on the differently stored cherries. L∗, chroma, and hue angle values were always lower for the ripe than for the partially ripe cherries. All of the cultivars were found to contain cyanidin-3-rutinoside and cyanidin-3-glucoside as the major anthocyanins. The total anthocyanin content in fruits of the different cultivars varied in the order Burlat > Saco > Van > Summit. The concentration of anthocyanins increased at both temperatures of storage in both ripe and partially ripe cherries, but the extent of increase varied among cultivars. Cherries stored at 15 ± 5 °C showed higher reduction of L∗, chroma and hue angle than fruits stored at 1.5 ± 0.5 °C. L∗, a∗, b∗, chroma and hue angle correlated negatively (P < 0.001) with the total anthocyanins levels, but not with the total phenols. These results show that chromatic functions of chroma and hue correlate closely with the evolution of colour and anthocyanins levels during storage of sweet cherries and indicate that colour measurements can be used to monitor pigment evolution and anthocyanin contents of cherries (and vice versa). 相似文献
4.
文章对脉冲化系统中扫描板产生的线性加速效应和附加离子能散作了研究,给出了离子能散曲线。提出了在时间压缩磁铁的入、出口处各加一个可在水平方向旋转和平移的磁屏蔽,可克服由于这种能散在磁铁后的靶上产生的色散。在靶上可得1ns的脉冲质子束,束斑大小为3×4mm~2。 相似文献
5.
40Gb/s(STM-2 5 6)高速时分复用传输技术前景展望 总被引:4,自引:1,他引:3
随着技术的发展 ,4 0 Gb/ s(STM- 2 5 6 )作为 10 Gb/ s(STM- 6 4)传输业务颗粒的后续者 ,开始逐渐为业界熟悉。就 4 0 Gb/ s这一新兴技术的市场推动因素、应用场合以及影响 4 0 Gb/ s传输的一些关键技术作了介绍 ,并对其将来的应用前景作出展望 相似文献
6.
7.
从已有的消色差系统中的束流尾场效应公式,变换成六维传输矩阵的形式,并扩充束流传输计算机程序TRANSPORT-EM/PC的功能,使之能用以计算尾场效应。最后,通过计算机数值计算,给出了一些实例的束流尾场效应对消色差系统中轨道色散和角色散变化的图表曲线。 相似文献
8.
介绍了一种自动测试汽车车灯色度仪器的设计原理、结构框图和精度分析。仪器采用微机控制、数据采集、标准判别和表格打印, 是车灯行业理想的测试仪器。 相似文献
9.
The dependence of high-resolution transmission electron microscopy (HRTEM) image contrast of graphene on the adjustable parameters of an aberration-corrected microscope operated at 80 and 20 kV has been calculated and, for 80 kV, compared with measurements. We used density functional theory to determine the projected atom potential and obtained the image intensity by averaging over the energy distribution of the imaging electrons, as derived from the electron energy loss spectroscopy measurements. Optimum image contrast has been determined as a function of energy spread of the imaging electrons and chromatic aberration coefficient, showing that significant improvement of contrast can be achieved at 80 kV with the help of a monochromator, however at 20 kV only with chromatic aberration correction and bright atom contrast conditions. 相似文献
10.
《全球能源互联网(英文)》2020,3(5):494-503
Partial discharge (PD) detection is an effective means of discovering insulation faults in gas-insulated switchgear (GIS). One of the most extensively used methods in PD detection has historically been the ultrahigh frequency (UHF) method. This study evaluates the chromatic processing methodology and its key factors for feature extraction of UHF signals in GIS. Three types of artificial defects are installed in the GIS tank at 0°, 90°, and 180°, respectively. The features of the UHF signals are extracted in the chromatic space, and PD discrimination of the defects is achieved. The influences of processors are studied before the feature selections are suggested. The time-stepping method is proposed to determine the rules of UHF signal frequency characteristics that vary with time. Finally, the process and options of the chromatics-inspired methodology are summarized. 相似文献