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11.
The transport of gaseous ethylene oxide (EtO) in several polymer films is studied using the carrier gas method of measurement. Permeability, solubility, and diffusion coefficients describing ethylene oxide (EtO) transport in polypropylene, polyvinylchloride, Teflon-FEP copolymer, and polyethylene films have been obtained over a 30 Celsius degree range at a low concentration of EtO using the carrier gas method of measurement. The results indicate that the diffusion of EtO in polyethylene is independent of penetrant concentration over the range of concentrations used. However, concentration-independent diffusion could not be verified directly for the other films studied. Two different techniques of determining diffusion coefficients were used, and within the precision of the data both yield the same result. An excess enthalpy of solution for the solubility of EtO in Teflon-FEP copolymer was calculated, an observation that suggests that dual-mode sorption may be taking place. 相似文献
12.
MJ King S Pugazhenthi RL Khandelwal RK Sharma 《Canadian Metallurgical Quarterly》1993,1165(3):259-262
N-Myristoyl transferase (NMT) is the enzyme that covalently modifies several proteins important in signal transduction. Streptozotocin-induced diabetes resulted in a 2-fold increase in NMT activity from rat liver as compared to control animals. Administration of sodium orthovanadate to the diabetic rats reduced the activity of the NMT to 75-120% of the control values. Elevated NMT activity was observed with both cAMP-dependent protein kinase-derived and pp60src-derived peptide substrates. No significant change in the apparent Km was observed with the cAMP-dependent protein kinase-derived peptide substrate. Unlike in rat brain, in all conditions highest NMT activity was observed in the particulate fraction of rat liver. 相似文献
13.
The complexation of copper (Cu+2), mercury (Hg+2) and silver (Ag+) ion with isopropylmercaptan has been studied in 25% (V/V) ethanolic media employing potentiometric, conductometric and amperometric titration techniques. Copper and mercury ions form 1:2 complex while silver ion shows the formation of 1:1 complex. Equilibrium constants and solubility products of these complexes have been evaluated by Ringbom's method at 10°, 20° and 30°C. The overall changes in thermodynamic functions ΔG, ΔH and ΔS accompanying complexation have also been determined at 20°C with the help of an isobar and Gibb's Helmholz equation. 相似文献
14.
Polyphenols and tannins in Indian pulses: Effect of soaking,germination and pressure cooking 总被引:1,自引:0,他引:1
Shweta Khandelwal Shobha A. Udipi Padmini Ghugre 《Food research international (Ottawa, Ont.)》2010,43(2):526-530
Polyphenols and tannins have implications for health and nutrition. There is limited information on their content in pulses, raw or post-processing. We estimated the concentrations of polyphenols and tannins in different cultivars of four pulses commonly consumed in India – Phaseolus aureus, Cajanus cajan, Lens esculenta and Cicer arietinum – and examined the effects of domestic processing. Means and standard deviations were calculated and results were analyzed by ANOVA. There were significant differences (P < 0.001) in the polyphenol and tannin contents of cultivars of the same pulse, with the exception of the tannin contents of pressure-cooked red gram cultivars (P = 0.3103). Processing reduced the concentrations of polyphenols by 19–59% and of tannins by 22–59%. A trend was observed in the degree to which processing reduced polyphenol and tannin contents (germination > pressure-cooking > soaking). Soaking, germination and pressure-cooking proved to be effective household strategies to reduce the levels of polyphenols and tannins in pulse-based foods, thereby enhancing the bioavailability of pulse protein. There is a need to determine the extent to which the remaining polyphenols and tannins are rendered unavailable by these processing techniques. 相似文献
15.
Ankit Khandelwal Rahil Gupta Radhapiyari Laishram K. Chandramani Singh 《Ceramics International》2019,45(8):10371-10379
Conventional solid state sintering method was used to synthesize lead-free (Ba0.91Ca0.09Sn0.07Ti0.93)O3-xHo2O3 (x?=?0, 1.2,1.4,1.6,1.8 and 2.0?mol%) ceramics. The influence on electrical properties of the system as a result of the structural and microstructural changes introduced by the incorporation of rare earth Ho3+ ions has been investigated. The X-ray diffraction analysis reveals that Ho3+ ions completely diffuse into the (Ba0.91Ca0.09Sn0.07Ti0.93)O3 lattice to form a homogeneous solid solution with a pure perovskite structure having tetragonal symmetry. Evidence of Ho3+ substituting Ti4+ via the oxygen vacancy compensation mechanism exists in the range of 0–1.6?mol % Ho content, while the self-compensation mode is the preferred mechanism beyond 1.6?mol %. The average grain size exhibits a drastic reduction from 16?μm to 0.7?μm as the Ho content increases from 0 to 1.6?mol%, followed by a slight increase at higher Ho concentration. It suggests that addition of Ho3+ inhibits grain growth in the ceramics. In the composition range studied, increasing Ho3+ content produces a gradual decrease in the relative density from 93% to 81%, room temperature dielectric constant (εrt) from 3997 to 807, electromechanical coupling factor (kp) from 0.23 to 0.06, and piezoelectric charge constant (d33) from 102 to 38?pC/N. This degradation in the properties is attributed to the crystalline and microstructural changes driven by the increasing presence of Ho content in the ceramics. 相似文献
16.
Parabolic trough solar collector (PTSC) is one of the most proven technologies for large‐scale solar thermal power generation. Currently, the cost of power generation from PTSC is expensive as compared with conventional power generation. The capital/power generation cost can be reduced by increasing aperture sizes of the collector. However, increase in aperture of the collector leads to higher heat flux on the absorber surface and results in higher thermal gradient. Hence, the analysis of heat distribution from the absorber to heat transfer fluid (HTF) and within the absorber is essential to identify the possibilities of failure of the receiver. In this article, extensive heat transfer analysis (HTA) of the receiver is performed for various aperture diameter of a PTSC using commercially available computational fluid dynamics (CFD) software ANSYS Fluent 19.0. The numerical simulations of the receiver are performed to analyze the temperature distribution around the circumference of the absorber tube as well as along the length of tube, the rate of heat transfer from the absorber tube to the HTF, and heat losses from the receiver for various geometric and operating conditions such as collector aperture diameter, mass flow rate, heat loss coefficient (HLC), HTF, and its inlet temperature. It is observed that temperature gradient around the circumference of the absorber and heat losses from the receiver increases with collector aperture. The temperature gradient around the circumference of the absorber tube wall at 2 m length from the inlet are observed as 11, 37, 48, 74, and 129 K, respectively, for 2.5‐, 5‐, 5.77‐, 7.5‐, and 10‐m aperture diameter of PTSC at mass flow rate of 1.25 kg/s and inlet temperature of 300 K for therminol oil as HTF. To minimize the thermal gradient around the absorber circumference, HTFs with better heat transfer characteristics are explored such as molten salt, liquid sodium, and NaK78. Liquid sodium offers a significant reduction in temperature gradient as compared of other HTFs for all the aperture sizes of the collector. It is found that the temperature gradient around the circumference of the absorber tube wall at a length of 2 m is reduced to 4, 8, 10, 13, and 18 K, respectively, for the above‐mentioned mass flow rate with liquid sodium as HTF. The analyses are also performed for different HTF inlet temperature in order to study the behavior of the receiver. Based on the HTA, it is desired to have larger aperture parabolic trough collector to generate higher temperature from the solar field and reduce the capital cost. To achieve higher temperature and better performance of the receiver, HTF with good thermophysical properties may be preferable to minimize the heat losses and thermal gradient around the circumference of the absorber tube. 相似文献
17.
The static behavior of composites and sandwich plates in thermo-mechanical environment is investigated by a two dimensional (2D) FE model. An efficient higher-order zig-zag theory (HOZT) considering actual through-thickness temperature profile and a least square error (LSE) method to accurately predict the inter-laminar stresses is implemented in this model. The in-plane displacement field is obtained by superposing a cubically varying global displacement field on a zig-zag displacement field having different slopes at each layer. This plate theory represents parabolic through thickness variation of transverse shear stresses, which satisfy the inter-laminar continuity at the layer interfaces and zero transverse shear stress conditions at the top and bottom of the plate. In the present 2D finite element (FE) model, the first derivatives of transverse displacement have been treated as independent variables to circumvent the problem of C1 continuity associated with the above plate theory (HOZT). The accurate through-thickness distribution of temperature is obtained by using a linear zig-zag thermal lamination theory proposed by the authors by using the thermal conduction properties of different constituent layers in the thickness direction. The LSE method is applied at the postprocessing stage to accurately calculate the inter-laminar stresses by the 3D equilibrium equations of the plate problem, after in-plane stresses are calculated. The proposed combined FE model (HOZT+LSE) is implemented to analyze the static behavior of laminated composites and sandwich plates subjected to thermo-mechanical loadings. Many new results are also presented that should be useful for the future reference. 相似文献
18.
Sharma Dileepkumar Ramlal Jainy Sachdeva Chirag Kamal Ahuja Niranjan Khandelwal 《International journal of imaging systems and technology》2019,29(2):146-160
This research proposes an improved hybrid fusion scheme for non-subsampled contourlet transform (NSCT) and stationary wavelet transform (SWT). Initially, the source images are decomposed into different sub-bands using NSCT. The locally weighted sum of square of the coefficients based fusion rule with consistency verification is used to fuse the detailed coefficients of NSCT. The SWT is employed to decompose approximation coefficients of NSCT into different sub-bands. The entropy of square of the coefficients and weighted sum-modified Laplacian is employed as the fusion rules with SWT. The final output is obtained using inverse NSCT. The proposed research is compared with existing fusion schemes visually and quantitatively. From the visual analysis, it is observed that the proposed scheme retained important complementary information of source images in a better way. From the quantitative comparison, it is seen that this scheme gave improved edge information, clarity, contrast, texture, and brightness in the fused image. 相似文献
19.
Wireless Personal Communications - A novel UWB microstrip antenna is proposed for C, X, and Ku bands wireless applications. An impedance bandwidth of 107.7% ranging from 4.5 to 15 GHz is... 相似文献
20.
Manohar Kakunuri Nandula D. Wanasekara Chandra S. Sharma Mudrika Khandelwal Stephen J. Eichhorn 《应用聚合物科学杂志》2017,134(15)
Three‐dimensional polymer nanofibrous mats with tunable wettability have been fabricated using a single step non‐conductive template assisted electrospinning process. Cellulose acetate nanofibers are electrospun over a nylon mesh, which acts as the template. The as‐deposited fiber mat is removed from this template to produce a free standing three‐dimensional micropatterned nanofibrous mat. By simply varying the template mesh dimensions, the fraction of the air‐liquid interface can be changed which allows control of the wetting mechanics. It is shown that the water contact angle can be varied from about 30° for a planar network to about 140° for a patterned mat implying a complete transition from hydrophilic to hydrophobic behavior. Furthermore, upon stretching the fiber mat loses its pattern irreversibly and reducing the contact angle from 140° to 110° with increasing stretching. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44709. 相似文献