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101.
The growth of epitaxial films on featured substrates has an important device application in junction-confinement, double hetero-structure
light emitting diodes. These devices are presently grown by a liquid phase epitaxy process but growth by metalorganic chemical
vapor deposition is desirable because of MOCVD's superior surface quality, uniformity, and throughput. This paper describes
the effect of growth parameters on AlGaAs films deposited by atmospheric-pressure MOCVD into substrate holes typically made
in the fabrication of junction-confinement LEDs. MOCVD growth replicates the substrate features; it does not give a planar
surface over the holes. The behavior of epitaxy filling into holes is strongly dependent on growth temperature and total gas
flow and largely independent of substrate misorientation and the thickness of the layer grown. Wet-etched holes formed (ll0)-oriented
V-groove and dovetail-groove features on the hole circumference. Faceting of the MOCVD growth was seen on the wall with the
(111)A feature while smooth growth was seen on the etched (111)B surface.
Deceased. 相似文献
102.
Chakrapani V. Varanasi Leon Chuck Lyle Brunke Jack Burke Andrew D. Chaney Paul N. Barnes 《Journal of Electronic Materials》2007,36(10):1265-1269
A simple testing method is used to compare the yield strengths (YS) of biaxially textured metallic substrates (Ni and its
alloys) presently under development for YBa2Cu3O7−x
coated conductors. This method is based on a retired ASTM D3379 tensile test standard method that was originally recommended
for single filament materials. Several common textured substrates, such as Ni, Ni-3at.%W, and Ni-5at.%W, procured from different
manufacturers, were tested using this method, and the data were compared with the values reported in the literature. A new
alloy substrate (constantan (Cu55-Ni44-Mn1wt.%)) that is biaxially textured in-house was also tested using this method, and
the YS data were compared with those of other substrates. For the substrates used in this study, the data obtained using this
method indicated that Ni substrates have YS of ∼52 MPa, Ni-3at.%W substrates have YS of ∼106 MPa, Ni-5at.%W substrates have
YS 163 MPa, and Cu55-Ni44-Mn1 wt.% substrates have YS of 74 MPa. 相似文献
103.
104.
105.
The effects of the process parameters of ultrasonic power and normal bonding force on bond formation at ambient temperatures
have been investigated with scanning electron microscopy (SEM) and energy-dispersive x-ray (EDX) analysis. A model was developed
based on classical microslip theory1 to explain the general phenomena observed in the evolution of bond footprints left on the substrate. Modifications to the
model are made due to the inherent differences in geometry between ball-bonding and wedge-bonding. Classical microslip theory
describes circular contacts undergoing elastic deformation. It is shown in this work that a similar microslip phenomenon occurs
for elliptical wire-to-flat contacts with plastically deformed wire. It is shown that relative motion exists at the bonding
interface as peripheral microslip at lower powers, transitioning into gross sliding at higher powers. With increased normal
bonding forces, the transition point into gross sliding occurs at higher ultrasonic bonding powers. These results indicate
that the bonding mechanisms in aluminum wire wedge-bonding are very similar to those of gold ball-bonding, both on copper
substrate. In ultrasonic wedge-bonding onto copper substrates, the ultrasonic energy is essential in forming bonding by creating
relative interfacial motion, which removes the surface oxides. 相似文献
106.
Annealing effects of a high-quality ZnTe substrate 总被引:1,自引:0,他引:1
Kenji Yoshino Minoru Yoneta Kenzo Ohmori Hiroshi Saito Masakazu Ohishi Takayuki Yabe 《Journal of Electronic Materials》2004,33(6):579-582
The sharp photoluminescence (PL) and optical-reflection spectra in the bandedge region of the high-quality nondoped ZnTe substrate
(100) were observed at 4.2 K. Free exciton, associated with lower and upper polaritons (EXL and EXU) at 2.382 eV and 2.381 eV, respectively, were clearly observed. This meant that this substrate was high quality. The intensity
of a bound exciton peak (2.375 eV), which is caused by a Zn vacancy, of a neutral acceptor decreased with an increase of the
Zn vapor pressures. 相似文献
107.
Molecular beam epitaxy growth of high-quality HgCdTe LWIR layers on polished and repolished CdZnTe substrates 总被引:2,自引:0,他引:2
R. Singh S. Velicu J. Crocco Y. Chang J. Zhao L. A. Almeida J. Markunas A. Kaleczyc J. H. Dinan 《Journal of Electronic Materials》2005,34(6):885-890
We report here molecular beam epitaxy (MBE) mercury cadmium telluride (HgCdTe) layers grown on polished and repolished substrates
that showed state-of-the-art optical, structural, and electrical characteristics. Many polishing machines currently available
do not take into account the soft semiconductor materials, CdZnTe (CZT) being one. Therefore, a polishing jig was custom designed
and engineered to take in account certain physical parameters (pressure, substrate rotational frequency, drip rate of solution
onto the polishing pad, and polishing pad rotational velocity). The control over these parameters increased the quality, uniformity,
and the reproducibility of each polish. EPIR also investigated several bromine containing solutions used for polishing CZT.
The concentration of bromine, as well as the mechanical parameters, was varied in order to determine the optimal conditions
for polishing CZT. 相似文献
108.
Dual-band infrared detectors made on high-quality HgCdTe epilayers grown by molecular beam epitaxy on CdZnTe or CdTe/Ge substrates 总被引:2,自引:0,他引:2
P. Ballet F. Noël F. Pottier S. Plissard J. P. Zanatta J. Baylet O. Gravrand E. De Borniol S. Martin P. Castelein J. P. Chamonal A. Million G. Destefanis 《Journal of Electronic Materials》2004,33(6):667-672
In this paper, we present all the successive steps for realizing dual-band infrared detectors operating in the mid-wavelength
infrared (MWIR) band. High crystalline quality HgCdTe multilayer stacks have been grown by molecular beam epitaxy (MBE) on
CdZnTe and CdTe/Ge substrates. Material characterization in the light of high-resolution x-ray diffraction (HRXRD) results
and dislocation density measurements are exposed in detail. These characterizations show some striking differences between
structures grown on the two kinds of substrates. Device processing and readout circuit for 128×128 focal-plane array (FPA)
fabrication are described. The electro-optical characteristics of the devices show that devices grown on Ge match those grown
on CdZnTe substrates in terms of responsivity, noise measurements, and operability. 相似文献
109.
Farid Akhtar 《Surface & coatings technology》2007,201(24):9603-9609
TiB2 and TiC reinforced Fe matrix thick films (2 mm thickness) were produced through the synthesis reaction from Ti, C and FeB powders with varying porosity on the steel substrates. Powder technology was used as a processing method. The films and the substrates were sintered in a single step. TiB2, TiC and Fe were detected in the films by X-ray diffraction analysis. The fact that no other reaction product was detected revealed the thermal stability of TiB2 and TiC. The formation of secondary reaction products was inhibited during the reactive sintering. The films showed maximum strength of 163-466 MPa when sintered separately at 1350 °C. The strength of the films varied with their porosity. The films showed considerable bonding strength with the steel substrates. The delamination of the films from the steel substrates was observed at stress values from 454-781 MPa. The microstructure, fracture and delaminated surface morphologies were studied. The wear resistance against hardened high speed steel was studied in reciprocating sliding tests. The wear mechanisms were discussed by means of microscopical observation on the worn surfaces. 相似文献
110.
S. P. Gorkhali D. R. Cairns G. P. Crawford 《Journal of the Society for Information Display》2004,12(1):45-49
Abstract— Failure mechanisms for flexible conducting substrates are investigated herein in the context of rollable/flexible display applications. Cyclic loading experiments (substrates subjected to multiple cycles of tensile strain) were carried out on both ITO‐coated PET and PEDOT:PSS‐coated PET substrates. The resistance was measured after each bending cycle. The resistance increased with the number of cycles and was not reversible. Even when the tensile strain on the ITO/PET was below the virgin cracking threshold (~2%) previously reported [Appl Phys Lett 76, 1425 (2000)], slight increases in resistance were measurable after just a few cycles. 相似文献