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1.
Summary The influence of draw ratio on macroscopic and crystallographic density of polyethylene with different initial morphologies, has been investigated by solid-state extrusion. An initial drop followed by an increase in macroscopic density as a function of draw ratio has been observed. Since precision X-ray measurements of unit cell parameters showed no variation of crystallographic density, it was concluded that plastic deformation of polyethylene upon drawing proceeds with a decrease of the degree of crystallinity. This was confirmed by differential scanning calorimetry. 相似文献
2.
Christian P. Romero Jonathan I. Avila Edgardo Cisternas Guerau B. Cabrera Alejandro L. Cabrera Kristiaan Temst Margriet J. Van Bael 《Journal of Materials Science》2007,42(18):7667-7672
Hydrogen desorption curves were obtained from a sample composed of a square arrangement of Co dots with average diameter of
4.4 μm, separated by a distance of 11.6 μm. A macroscopic sample of Co dots grown on a 2.5 × 2.5 cm Si substrate was made
by standard lithographic techniques and used in these experiments. Thermal programmed desorption (TPD) was performed under
ultra-high vacuum conditions. Hydrogen TPD curves were obtained from a 1 × 1 cm Co dots samples displaying a maximum of intensity
at 425 K. Hydrogen TPD curve was also obtained from 1 cm× 1 cm samples of Co films and Co foils for comparison. The hydrogen
TPD curves have decreasing intensity from the Co foils to the Co dots and finally to the Co films. This indicates that there
are more sites for hydrogen adsorption on the Co dots than in the Co films. This is a surprising result because there is approximately
8.7 times less Co atoms exposed in the Co dots that in the Co film sample. A desorption energy of 27 kcal/mol was obtained
for the Co dots suggesting that hydrogen is adsorbed on an hcp hollow site of the Co dot crystalline structure. 相似文献
3.
An adaptive color similarity function suitable for image segmentation and its numerical evaluation
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Rodolfo Alvarado‐Cervantes Edgardo M. Felipe‐Riverón Vladislav Khartchenko Oleksiy Pogrebnyak 《Color research and application》2017,42(2):156-172
In this article, we present an adaptive color similarity function defined in a modified hue‐saturation‐intensity color space, which can be used directly as a metric to obtain pixel‐wise segmentation of color images among other applications. The color information of every pixel is integrated as a unit by an adaptive similarity function thus avoiding color information scattering. As a direct application we present an efficient interactive, supervised color segmentation method with linear complexity respect to the number of pixels of the input image. The process has three steps: (1) Manual selection of few pixels in a sample of the color to be segmented. (2) Automatic generation of the so called color similarity image (CSI), which is a gray level image with all the gray level tonalities associated with the selected color. (3) Automatic threshold of the CSI to obtain the final segmentation. The proposed technique is direct, simple and computationally inexpensive. The evaluation of the efficiency of the color segmentation method is presented showing good performance in all cases of study. A comparative study is made between the behavior of the proposed method and two comparable segmentation techniques in color images using (1) the Euclidean metric of the a* and b* color channels rejecting L* and (2) a probabilistic approach on a* and b* in the CIE L*a*b* color space. Our testing system can be used either to explore the behavior of a similarity function (or metric) in different color spaces or to explore different metrics (or similarity functions) in the same color space. It was obtained from the results that the color parameters a* and b* are not independent of the luminance parameter L* as one might initially assume in the CIE L*a*b* color space. We show that our solution improves the quality of the proposed color segmentation technique and its quick result is significant with respect to other solutions found in the literature. The method also gives a good performance in low chromaticity, gray level and low contrast images. © 2016 Wiley Periodicals, Inc. Col Res Appl, 42, 156–172, 2017 相似文献
4.
Plaza-Cazón Josefina González Esteban Donati Edgardo Rubén 《Mine Water and the Environment》2021,40(4):994-1002
Mine Water and the Environment - The role of iron- and sulfur- oxidizing microorganisms in the generation of acid mine drainage (AMD) from sulfide ores and tailings is widely recognized. The... 相似文献
5.
Alejandra Tironi Mónica A. TrezzaAlberto N. Scian Edgardo F. Irassar 《Construction and Building Materials》2012,28(1):276-281
Five natural kaolinitic clays from different regions of Argentine, with different kaolinite content, different impurities and different degree of crystallinity were calcined in a fixed-bed electrical furnace at 700 °C. Clays were characterized by X-ray diffraction (XRD) and Fourier transformed infra-red spectrometry (FTIR) that provides an index about the order/disorder of the structure. After heat treatment, the structural changes were characterized by XRD and FTIR, and pore size distribution and specific surface were determined. Their pozzolanic activity was evaluated with the Frattini test, electrical conductivity in saturated Ca(OH)2 solution and compressive strength on mortars at 7, 28 and 90 days. Among tested clays, four of them can be classified as pozzolan by the Frattini test. The pozzolanic activity of the natural clays showed good correlation with the content of kaolinite, the inversed of structure order determined by FTIR, and the specific surface of calcined clays. This study confirms that natural clays other than pure kaolinite can be interesting pozzolanic materials when thermally activated. 相似文献
6.
7.
Cognition, Technology & Work - Organizations require good performance from individuals to achieve their objectives. In view of the growing presence of technology, it becomes necessary to... 相似文献
8.
Exercise training-induced changes in sensitivity to endothelin-1 and aortic and cerebellum lipid profile in rats 总被引:2,自引:0,他引:2
Latorre E Morán M Aragonés MD Saborido A Fernández I Delgado J Catalán RE Megías A 《Lipids》2002,37(1):43-52
The purpose of this work was to study whether exercise training induces changes in the lipid profile of rat aorta and nervous
system and in the in vitro intrinsic responsiveness of these tissues to endothelin-1 (ET-1) treatment. The exercise program performed successfully produced
the characteristic metabolic alterations of the trained state. Exercise training induced a large and significant increase
in the levels of both aortic ethanolamine plasmalogens (PlasEtn) and glucosylceramides. In contrast, a decrease of aortic
ceramide and cholesterol levels was evoked by exercise training. ET-1 increased PlasEtn content only in sedentary animals.
An exercise-induced increase in cerebellum levels of ceramides and ceramide monohexosides was found. The cerebellum ceramide
content was increased by FT-1 more noticeably in sedentary rats than in trained animals. In contrast, cerebral cortex was
observed to be largely insensitive to both exercise training and ET-1 treatment. It was concluded that exercise training (i)
induces changes in both vascular and cerebellar lipid profiles, the former being much more pronounced than the latter, and
(ii) diminishes the aortic and cerebellar sensitivity to ET-1 action. 相似文献
9.
A batch-indirect rotary drier heated with steam was experimentally operated to obtain data of moisture content and temperature versus time for soy meal and fish meal. Operation conditions were as follow: steam pressure (1 to 4 bar), rotation speed (3.7 to 11.6 r.p.m.) and rate of vapor extraction (0.059 to 0.256 m/s).
From experimental data the effective heat transfer coefficient between the hot surface and the bed of solids was determined. These data were correlated by means of dimensional analysis as a function of the drying process variables. The equation obtained for the effective Nusselt number predicts adequately the effective heat transfer coefficient, for both substrates, in the range of the operating variables studied. 相似文献
From experimental data the effective heat transfer coefficient between the hot surface and the bed of solids was determined. These data were correlated by means of dimensional analysis as a function of the drying process variables. The equation obtained for the effective Nusselt number predicts adequately the effective heat transfer coefficient, for both substrates, in the range of the operating variables studied. 相似文献
10.
F Dagenais R Cartier JM Farinas Y Leclerc G Hudon 《Canadian Metallurgical Quarterly》1998,14(9):1121-1125
OBJECTIVES: To evaluate the value of concomitant coronary endarterectomy (CE) in the modern era of coronary revascularization. METHODS: Retrospective study. Twenty-eight patients (five women; 23 men) who underwent coronary endarterectomy were angiographically studied 24 +/- 22 months after the procedure. Necessity CE (vessel completely occluded or with lumen less than 1 mm) was performed on the left anterior descending (LAD) artery in 12 patients, the right coronary artery (RCA) in nine, the obtuse marginal artery (OM) in five and a diagonal branch in two patients. Conduits used for revascularization were the internal thoracic artery (ITA) in 11 (all anastomosed to the LAD; combined with saphenous vein patch in four) and a saphenous vein graft in 17 patients. Mean atherosclerotic core length was 3.3 +/- 1.8 cm. An average of 3.1 +/- 0.7 distal anastomoses per patient were constructed, with mean aortic cross-clamp and cardiopulmonary bypass times of 61.2 +/- 20.2 mins and 94.0 +/- 23.5 mins, respectively. RESULTS: Overall, angiographic patency rate was 71% (20 of 28) for the endarterectomized vessels (12 of 12 LAD, six of nine RCA, two of five OM and none of two diagonal arteries) and 93% (57 of 61) for the nonendarterectomized vessels. Among the eight patients with occluded CE vessels, two sustained a perioperative myocardial infarction, five developed angina during follow-up, and one patient remained asymptomatic. CONCLUSION: Necessity CE demonstrates acceptable mid-term patency. In addition, this study showed excellent patency following CE of the LAD revascularized with the ITA, with or without only a saphenous vein patch. 相似文献