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233.
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
234.
Abstract Using a hard dead space impact ionization model, the dependence of breakdown probabilities on overbias ratio in single photon avalanche diodes is investigated theoretically in a variety of semiconductor materials for the simple case of constant electric field, that is, in a p+-i-n+ diode structure. By using avalanche widths of 2 μm, the effects of dead space are minimized so that the breakdown probability results are determined primarily by the enabled ionization coefficients of the materials. The results illustrate how the slope of breakdown probability with overbias ratio is affected by the enabled ionization coefficients ratio and by the field dependences of ionization coefficients, which should be taken into account when choosing semiconductor materials for single photon avalanche diodes. 相似文献
235.
Studies of the mechanisms and the effects on the flowing mobility for hazardous geophysical flows (e.g., debris flows) is
crucial for hazard mitigation and prediction. Granular flows with grains of mixed sizes are numerically modeled and the contact
behavior of solid particles is fundamentally studied using the discrete element method. The mechanical effects of particle
contacts (shearing and collision) are contrasted with geometrical effects (kinetic sieving) to explain the mechanism of reverse
segregation. Compared to granular flows with uniform solid particles, the effect of segregation on granular flowing mobility
is investigated. It is found that reverse segregation can significantly influence the flowing mobility and the flowing regimes
in the front head of the granular body. A mechanical explanation of the segregation mechanism can be presented by a new dimensionless
number, which is correlated with the contact force. 相似文献
236.
A mathematical model is presented for the problem of apparent slip arising from Stokes shear flow over a composite surface
featuring mixed boundary conditions on the microscale. The surface can be composed of a bidimensional array of solid areas
placed on an otherwise no-shear surface corresponding to an envelope over the tops of posts, or no-shear areas placed on an
otherwise solid surface corresponding to an envelope over the tops of holes. Posts and holes of circular or square cross section,
and solid areas of no-slip or partial-slip types are studied. Following some previously proposed scaling laws, the effective
slip length is expressed as a certain function of the solid fraction for some specific cases. More refined equations based
on linear regression of the computed results are obtained for these cases. Amounts of slippage arising from these bidimensional
patterns are compared with those from the one-dimensional patterns of grooves/grates. It is also shown that a larger slip
length can result from an arrangement where the pitch is larger in the spanwise direction than in the streamwise direction. 相似文献
237.
Kapila Wadumesthrige Nicholas JohnsonMark Winston-Galant Sidong ZengEric Sattler Steven O. SalleyK.Y. Simon Ng 《Applied Energy》2010
The long term performance and durability evaluation of a compression ignition (CI) engine of a diesel power generator using ultra-low sulfur diesel (ULSD) and Synthetic Paraffinic Kerosene, (S-8) fuels have been investigated under military specifications. The brake specific fuel consumptions (BSFC) were 0.308 ± 0.013 and 0.267 ± 0.019 kg/kW-h for ULSD and S-8, respectively. The corresponding brake thermal efficiencies (BTE) were 0.287 ± 0.002 and 0.309 ± 0.005. Degradation of engine performance or engine part wear was not observed during these test periods. Analysis of lubricating oil suggests negligible engine part wear. The frequency and power output of the generator, however, were not as stable with S-8 as those with ULSD. These power and frequency instabilities can be attributed to higher volatility and lower density and viscosity of S-8, all of which affect the fuel injection characteristics. 相似文献
238.
Radioactivity measurements were carried out on some Malaysian marine species using gross γ‐ray spectrometry. 137Cs levels of the order of 7 to 10 Bq/dry kg were detected in the larger‐sized species whereas considerably lower levels were found in the smaller‐sized ones. No other artificial radioisotopes were present in significant concentrations. 40K levels ranged from about 70 to 567 Bq/dry kg. The concentration factors for both l17Cs and 40K in these samples were also reported. 相似文献
239.
Summary Poly(lactic acid) (PLA) was melt blended with epoxidized soybean oil (ESO) in an internal mixer and thermal, mechanical and
rheological properties of the blends were investigated by means of differential scanning calorimetry, dynamic mechanical analysis,
tensile test and small amplitude oscillatory shear rheometry. ESO lowered glass transition temperature and increased the ability
of PLA to cold crystallization. The blend exhibited improved elongation-at-break along with a plastic deformation. The plasticization
effect by ESO was also manifested by the lowering of dynamic storage modulus and viscosity in the melt state of the blends
compared with neat PLA. 相似文献
240.
Pervaporation membranes were fabricated by blending different amount of zeolite NaA or NaX with three types of poly(amidesulfonamide) (PASA). The zeolite‐filled membranes were characterized by IR spectroscopy, SEM, sorption measurements, and wide‐angle X‐ray diffraction. By adding the proper amount of NaA into the polymer casting solutions, the resultant zeolite‐filled membranes exhibited improvement in both selectivity and permeability in the separation of 10% aqueous solutions of ethanol and propan‐1‐ol, as compared with the zeolite free membrane. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1323–1329, 2001 相似文献