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排序方式: 共有419条查询结果,搜索用时 421 毫秒
1.
F.T. Munna Vidhya Selvanathan K. Sobayel Ghulam Muhammad Nilofar Asim Nowshad Amin Kamaruzzaman Sopian Md. Akhtaruzzaman 《Ceramics International》2021,47(8):11003-11009
In this study, dilute chemical bath deposition technique has been used to deposit CdZnS thin films on soda-lime glass substrates. The structural, morphological, optoelectronic properties of as-grown films have been investigated as a function of different Zn2+ precursor concentrations. The X-ray diffractogram of CdS thin-film reveals a peak corresponding to (002) plane with wurtzite structure, and the peak shift has been observed with the increase of the Zn2+ concentration upon formation of CdZnS thin film. From morphological studies, it has been revealed that the diluted chemical bath deposition technique provides homogeneous distribution of film on the substrate even at a lower concentration of Zn2+. Optical characterization has shown that the transparency of the film is influenced by Zn2+ concentration and when the Zn2+ concentration is varied from 0 M to 0.0256 M, bandgap values of resulting films range from 2.42 eV to 3.90 eV while. Furthermore, electrical properties have shown that with increasing zinc concentration the resistivity of the film increases. Finally, numerical simulation validates and suggests that CdZnS buffer layer with composition of 0.0032 M Zn2+ concentration would be a promising candidate in CIGS solar cell. 相似文献
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The effects of fluidized bed heat treatment on the microstructural and mechanical properties of Al-Si-Cu-Mg cast alloys, namely,
354 and 319, were studied. The heating rate in fluidized beds (FBs) is greatervis-à-vis conventional electrical resistance furnaces (CFs). The high heating rate in FBs increases the kinetics of metallurgical phenomena
such as Si fragmentation and spherodization during solution heat treatment, as well as the precipitation rate of phases such
as Al5Cu2Mg8Si6 and Al2Cu during aging. It is observed that the dissolution rate of phases such as Mg2Si and Al5Cu2Mg8Si6 takes place very rapidly. The solution heat treatment of 319 alloy using FB results in complete dissolution of Mg2Si and Al5Cu2Mg8Si6 particles within 45 minutes. However, for phases such as Al2Cu and Ferich intermetallics, the dissolution rate is relatively slow. Even on prolonged solution heat treatment for 6 hours,
these phases do not dissolve completely. It is observed that incomplete dissolution of the Al2Cu phase does not significantly affect tensile properties of T4-treated alloys. The optimum solution heat-treatment time in
FB for both 354 and 319 alloys is 45 minutes at 527 °C and 493 °C, respectively. Thermal analysis shows an exothermic peak
owing to recrystallization and coarsening of eutectic grains during solution heat treatment. The high heating rate in FB causes
this transformation to take place at a lower temperature than in CF. It is observed that the nucleation rate of Al5Cu2Mg8Si6 during aging in FB is greater than using CF. Thermal analysis of samples during the ramp-up stage while aging using FB did
not show any phase transformation, while those using CF show two endothermic transformations, which are most likely due to
the dissolution of GP zones or the co-cluster of solutes. Aging at 200 °C results in a greater number density of precipitates
than those at 240 °C. The tensile strength of samples aged at 200 °C is greater than those aged at 240 °C, because the amount
of precipitates formed at 200 °C is greater than that at 240 °C. The total heat-treatment time for T6 temper is less than
2 hours in FBs, which is a significant reduction in heat-treatment time, as well as energy consumption. 相似文献
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Jayanta Basak Koustav Bhattacharya Santanu Chaudhury 《IEEE transactions on image processing》2006,15(12):3773-3783
In this paper, we design a content-based image retrieval system where multiple query examples can be used to indicate the need to retrieve not only images similar to the individual examples, but also those images which actually represent a combination of the content of query images. We propose a scheme for representing content of an image as a combination of features from multiple examples. This scheme is exploited for developing a multiple example-based retrieval engine. We have explored the use of machine learning techniques for generating the most appropriate feature combination scheme for a given class of images. The combination scheme can be used for developing purposive query engines for specialized image databases. Here, we have considered facial image databases. The effectiveness of the image retrieval system is experimentally demonstrated on different databases. 相似文献
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Asim Muhammad Nabeel Ghani Muhammad Usman Ibrahim Muhammad Ali Mahmood Waqar Dengel Andreas Ahmed Sheraz 《Neural computing & applications》2021,33(11):5437-5469
Neural Computing and Applications - In order to provide benchmark performance for Urdu text document classification, the contribution of this paper is manifold. First, it provides a publicly... 相似文献
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The force needed to pull a cylindrical stud from a soft elastomeric film depends on their elastic and geometric properties. For a rigid stud and a thick elastomeric film, the pull-off stress (σ) depends on the elastic modulus (E) of the film and the radius (a) of the stud as σ ∼ (E/a)1/2 (soft adhesion). However, when the film is very thin, the pull-off stress is significantly higher than the case with thick films, and its value depends on the elastic modulus and the thickness (h) of the film as σ ∼ (E/h)1/2 (hard adhesion). Here, we study the pull-off behavior of a soft cylindrical stud, one flat end of which is coated with a high modulus thin baseplate. As the flexural rigidity of this baseplate is varied, we observe the transition between the two types of adhesion. We present a simple physical interpretation of the problem, which could be of value in understanding various biofouling and adhesive situations. 相似文献
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Firms are increasingly employing social media to manage relationships with partner organizations, yet the role of institutional pressures in social media assimilation has not been studied. We investigate social media assimilation in firms using a model that combines the two theoretical streams of IT adoption: organizational innovation and institutional theory. The study uses a composite view of absorptive capacity that includes both previous experience with similar technology and the general ability to learn and exploit new technologies. We find that institutional pressures are an important antecedent to absorptive capacity, an important measure of organizational learning capability. The paper augments theory in finding the role and limits of institutional pressures. Institutional pressures are found to have no direct effect on social media assimilation but to impact absorptive capacity, which mediates its influence on assimilation. 相似文献
10.
Epidemiological studies suggest the existence of a strong relationship between the incidence of prostatic cancer and the intake
of dietary lipids in humans. However, very little information is available on intracellular fatty acid metabolism in human
prostatic tissue. The objective of this study was to identify and subsequently characterize a fatty acid binding protein of
human prostatic tissue. A fatty acid binding protein (FABP) was purified and characterized from human prostatic tissue. The
purified FABP had an apparent molecular mass of 15.0±1.0 kDa as averaged from three different methods, sodium dodecylsulfate-polyacrylamide
gel electrophoresis (SDS-PAGE), gel filtration and amino acid analysis. The pI value of the protein was determined to be 6.8.
Scatchard analysis of fatty acid binding to the purified FABP from malignant prostatic tissue showed a Kd value of 0.53±0.02
μM for arachidonic acid (n=5). The Kd values of FABP purified from benign prostatic tissue were 0.57±0.02 μM for oleic acid
and 0.51±0.04 μM for arachidonic acid (n=5). Fatty acid analysis revealed that the level of endogenously bound arachidonic
acid was about 2.5-fold higher in FABP from malignant than from benign tissue. In addition, both malignant and benign tissues
contained the same concentration of FABP. The concentrations of FABP in malignant and benign tissues were 19.2±1.8 and 21.4±2.1
μg per mg of total cytosolic protein, respectively. Characterization based on amino acid composition, isoelectric point and
fluorescence with dansyl undecanoic acid suggests that the FABP may not be of the heart type, but is rather more closely related
to the liver type. As malignant prostatic tissue produces more PGE2 compared to benign tissue, our data suggest that FABP may help enhancing the synthesis of the prostaglandin in malignant
tissue by facilitating arachidonic acid transport.
A preliminary account of this work was presented at the Biochemical Society Meeting, London, December 16–18, 1991, and published
as an abstract (Ref. 1). 相似文献