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81.
A highly dispersive dual-concentric-core pure silica photonic crystal fiber is designed with a maximum chromatic dispersion value of about -9500 ps/(nm km) around the 1.56 microm wavelength region and a full width at half-maximum (FWHM) of 55 nm. The change in the dispersion-bandwidth product as a function of period is carefully studied by using the plane wave expansion method. The coupled mode theory matches well with the plane wave expansion method that was used to simulate the chromatic dispersion. This kind of a photonic crystal fiber structure is suitable for high-dispersion application in phased array antenna systems based on photonic crystal fiber arrays. 相似文献
82.
Harish Bahadur A. K. Srivastava R. K. Sharma Sudhir Chandra 《Nanoscale research letters》2007,2(10):469-475
We have shown that the morphological features of the sol–gel derived thin films of ZnO depend strongly on the choice of the
precursor materials. In particular, we have used zinc nitrate and zinc acetate as the precursor materials. While the films
using zinc acetate showed a smoother topography, those prepared by using zinc nitrate exhibited dendritic character. Both
types of films were found to be crystalline in nature. The crystallite dimensions were confined to the nanoscale. The crystallite
size of the nanograins in the zinc nitrate derived films has been found to be smaller than the films grown by using zinc acetate
as the precursor material. Selected area electron diffraction patterns in the case of both the precursor material has shown
the presence of different rings corresponding to different planes of hexagonal ZnO crystal structure. The results have been
discussed in terms of the fundamental considerations and basic chemistry governing the growth kinetics of these sol–gel derived
ZnO films with both the precursor materials.
相似文献
Harish BahadurEmail: |
83.
城域网和接入网发展需要的低水峰单模光纤 总被引:1,自引:1,他引:0
Shasgu kant Harish Taneja Sudipta Bhaumik Abhay Arora 《光通信研究》2005,(4):42-45
密集波分复用(DWDM)的出现扩大了长途传输网的容量,但是DWDM技术的复杂性和使用了昂贵的器件,限制了DWDM在城域网的应用.最新研制的光纤,其在整个宽工作带,包括在(1 380±3) nm上都具有低水峰.低水峰光纤与粗波分复用(CWDM)系统比用标准单模光纤(SMF)的同一系统所用的信道间隔宽33%.经过恶劣的环境试验证明,低水峰光纤具有稳定的抗氢气引起的衰减性能,可确保现场安装的低水峰光纤光缆长期可靠地工作.由于低水峰光纤具有优异的弯曲敏感性,使其与最近研制的宽带接入技术,即所谓的光纤到驻地(FTTP)完全相适应. 相似文献
84.
M.R. Savitha Prashanth K.S. Parvathy N.S. Susheelamma K.V. Harish Prashanth R.N. Tharanathan A. Cha G. Anilkumar 《Food Hydrocolloids》2006,20(8):1198-1205
Acetate, succinate and octenylsuccinate derivatives of galactomannans were prepared in anhydrous reaction conditions carried out at slightly elevated temperature (40–60 °C) using solid NaHCO3 as a mild base catalyst. Prior surface wetting of the reactants with 5% absolute ethyl alcohol gave derivatives with a higher degree of substitution, although it decreased the slurry viscosity. Use of NaHCO3 significantly minimized high pH-induced degradative reactions, and its quantitative removal later was easily accomplished by repeated washings with aqueous ethyl alcohol. FT-IR, 13C-NMR, HPSEC and SEM data provided additional structural information. These derivatives are useful as functional food ingredients. 相似文献
85.
A.B. Panda K. Harish S.V. Chaure V.S. Jadhav D. Sasmal A.K. Das I. Banerjee 《Surface & coatings technology》2010,205(5):1611-1617
TiO2 thin films have been deposited at different Ar:O2 gas ratios (20:80,70:30,50:50,and 40:60 in sccm) by rf reactive magnetron sputtering at a constant power of 200 W. The formation of TiO2 was confirmed by X-ray photoelectron spectroscopy (XPS). The oxygen percentage in the films was found to increase with an increase in oxygen partial pressure during deposition. The oxygen content in the film was estimated from XPS measurement. Band gap of the films was calculated from the UV-Visible transmittance spectra. Increase in oxygen content in the films showed substantial increase in optical band gap from 2.8 eV to 3.78 eV. The Ar:O2 gas ratio was found to affect the particle size of the films determined by a transmission electron microscope (TEM). The particle size was found to be varying between 10 and 25 nm. The bactericidal efficiency of the deposited films was investigated using Escherichia coli (E. coli) cells under 1 h UV irradiation. The growth of E. coli cells was estimated through the Optical Density measurement by UV-Visible absorbance spectra. The qualitative analysis of the bactericidal efficiency of the deposited films after UV irradiation was observed through SEM. A correlation between the optical band gap, particle size and bactericidal efficiency of the TiO2 films at different argon:oxygen gas ratio has been studied. 相似文献
86.
S. Sivasankaran V. Sivakumar P. Prakash 《International Journal of Heat and Mass Transfer》2010,53(19-20):4304-4315
A numerical study has been performed on mixed convection in a lid-driven cavity. The vertical sidewalls of the cavity are maintained with sinusoidal temperature distribution. A finite volume method is used to solve numerically the non-dimensional governing equations. Results are analyzed over a range of the Richardson numbers, amplitude ratios and phase deviations. The results show that heat transfer rate is increased on increasing amplitude ratio. It is observed that average Nusselt numbers are increased first and then decreased when increasing the phase deviation from 0 to π. The non-uniform heating on both walls provides higher heat transfer rate than non-uniform heating of one wall. 相似文献
87.
Harish K. Patney Christina Nordlund Adam Moy Harry Rose Brent Young Michael A. Wilson 《Fullerenes, Nanotubes and Carbon Nanostructures》2013,21(6):941-971
Abstract Graphite has normally been used to synthesise fullerenes and nanotubes. However, coal is a cheaper and more suitable industrial material. Because coal is a molecular solid, unlike graphite, the mechanism by which fullerene and nanotubes are formed is different. Moreover, other products such as polyaromatic hydrocarbons (PAHs) and microfibres are also formed. In this review, the mechanism of formation of fullerene and nanotubes from coal is discussed. It is shown that the pathway involved is other than through the C1 intermediate route. The influence of other elements in coal such as hydrogen, oxygen, sulfur and iron is also discussed. It appears that, hydrogen, oxygen, iron and sulfur affect the yield and type of fullerenes and nanotubes formed. 相似文献
88.
Naif H. Alsharif Said A. Farha Al‐Said Mark A. Birch Benjamin R. Horrocks Harish K. Datta 《Small (Weinheim an der Bergstrasse, Germany)》2013,9(21):3685-3692
The lack of an in vitro real‐time osteoclast (OC) activity assay has hampered mechanistic studies of bone resorption. Such an assay is developed, employing a hydroxyapatite matrix impregnated with alkyl‐capped silicon nanocrystals, which is capable of monitoring the time‐course of resorption by single osteoclasts. Resorption of the matrix by OC releases the nanocrystals, which are internalized by the cell and detected as an increase in OC luminescence. This particular choice of nanocrystals is motivated by their bright pH‐independent luminescence, proportional to concentration, and by their rapid uptake without cytotoxicity. In this in vitro assay, OCs are inhibited by calcitonin (CT) and methyl‐β‐cyclodextrin (MCD), and stimulated by receptor activator of nuclear factor kappa‐B ligand (RANKL) in the expected manner. The kinetics of the assay exhibit a lag phase representing cell attachment and commencement of resorption processes, followed by a growth of cell luminescence intensity, and the whole time‐course is satisfactorily described by the logistic equation. 相似文献
89.
S. Sivasankaran M. A. Mansour A. M. Rashad M. Bhuvaneswari 《Numerical Heat Transfer, Part A: Applications》2013,63(12):1356-1370
ABSTRACTA numerical simulation of magneto-hydrodynamic mixed convection flow and heat transfer of Cu–water nanofluid in a square cavity filled with a Darcian porous medium with a partial slip is numerically investigated. The left and right walls of the cavity are moving up with a constant speed in vertical direction, and the partial slip effect is considered along these walls. The top and bottom walls of the cavity are assumed to be adiabatic. The right vertical wall of the cavity is assumed to be kept at a lower temperature, while the left vertical wall is kept at a higher temperature. The developed equations of the mathematical model are nondimensionalized and then solved numerically subject to appropriate boundary conditions by the finite-volume method. A parametric study is performed and a set of graphical results is presented and discussed to demonstrate interesting features of the solution. 相似文献
90.
Niraj Chawake Sri Harish Kumar Paleti B. S. Murty Ravi S. Kottada 《Transactions of the Indian Institute of Metals》2013,66(4):419-424
In the present work, nanocrystalline FeAl and FeAl–Al2O3 composite were synthesized by high energy ball milling and subsequent compaction by spark plasma sintering. Microstructural changes during all stages of processing are studied using X-ray analysis. After 20 h of milling, the disordered FeAl and some amount of Fe rich solid solution was obtained in both of these compositions. Subsequent heat treatment results in formation of ordered FeAl. However, disordering of FeAl was observed in both compositions after spark plasma sintering. Nanocrystallinity is retained in both the compositions even after sintering at high temperature of 1,000 °C. Very high hardness of ~575 HV1 and ~600 HV1 was exhibited by FeAl and FeAl–Al2O3 composite. 相似文献