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101.
Simulations and designs are presented of conventional and periodic SO2 absorption from exhaust gases using salt water as absorption solvent. Operating conditions resemble those of a maritime operation, involving relatively small amounts of SO2, so the separation is in the linear region. The advantages of periodic operation, as already demonstrated for conventional distillation remain valid for absorption processes: Less tall towers, than staged towers are possible, or substantially less salt water is required for the process employing periodic cycling. 相似文献
102.
The aim of the study is to investigate if more competition leads to lower rents on the housing market. Data about the rent level for similar apartments in 30 cities in Sweden were available. Three hypotheses were formulated: (H1) Increased ‘internal’ competition, measured by the market share of the municipal housing company (that dominates the market and is price-leader according to the Swedish system of rent regulation), leads to lower rents. (H2) Increased ‘external’ competition measured by the price level on the market for single-family owner occupied housing, leads to lower rents. (H3) Lower capital expenditure in the municipal housing company leads to lower rents. The statistical analysis showed a strong correlation between the rent level and the level of external competition, but no relation was found for the level of internal competition and the level of capital expenditure. A possible conclusion is that policies that make it easier for households to leave the rental market are important for increasing the pressure on the firms in the rental sector and reducing rents. 相似文献
103.
The study evaluated the efficiency of two heat dissipation strategies under simulated desert patrol missions. Ten men participated in four trials, during which they walked on a treadmill (45°C, 20% relative humidity), carrying a load of 35 kg; two 50-min walks were separated by a 20-min rest. Cooling strategies, provided by an ambient air-ventilated vest (active cooling condition, AC), or water spraying of the skin during the rest (passive cooling condition, PC), in addition to reduced clothing and open zippers, were compared to conditions with full protective (FP) clothing and naked condition (NC). Skin temperature was higher during NC (37.9 ± 0.4°C; p < 0.001), and rectal temperature and heart rate were higher during FP (38.6 ± 0.4°C, p < 0.001 and 145 ± 12, p < 0.001, respectively), compared to other conditions. Four subjects terminated the trial prematurely due to signs of heat exhaustion in FP. Both cooling strategies substantially improved evaporative cooling. 相似文献
104.
The time-dependent traveling salesman problem (TDTSP) is a variant of TSP
with time-dependent edge costs. We study some restrictions of
TDTSP where the number of edge cost changes are limited. We find
competitive ratios for online versions of TDTSP. From these we
derive polynomial time approximation algorithms for graphs with
edge costs one and two. In addition, we present an approximation
algorithm for the orienteering problem with edge costs one and two. 相似文献
105.
Several applications for renewable energy conversion make use of variable speed generators. A conversion from variable frequency to grid frequency is therefore essential. One part of the converter is a rectifier. A rectifier model is presented, which is integrated in a time stepping finite element simulation environment where the generator and circuit equations are solved simultaneously. The model handles bidirectional alternator speeds as the application is a linear generator for ocean wave energy conversion. The rectifier model is extended with a load model, consisting of R, L and E, and simulations show what impact the rectifier has on the generator’s behaviour. 相似文献
106.
Clusters are generally organized in order to stimulate the growth and competitiveness of a region in a particular technological area. They occur in many shapes and forms, and a specific cluster development is the product of a dynamic and interactive process among the key stakeholders in the specific region. Any region seeking to succeed in high-tech fields must have stakeholders that are able to collaborate and innovate across sectors. This approach is achieved by combining the scientific, entrepreneurial, financial, and structural elements into a globally viewed competitive approach that is focused on specific goals. The Medicon Valley, which covers the greater Copenhagen area and the southern tip of Sweden, is born with the task to promote research, innovation, and commercialization across the board and to enhance network formations and knowledge transfer among all the players of Medicon Valley.This paper discusses how cluster formation helped in the development of the medico/human life science research in Medicon Valley which has for its members biotech and medtech companies, major pharmaceutical companies, all the relevant university faculties, hospitals, service providers, and public organizations. 相似文献
107.
Mikael Schill 《International journal for numerical methods in engineering》1988,26(8):1893-1905
A uniform linear semi-infinite beam in a uniform linear ambient medium is studied. The beam performs stationary harmonic damped non-synchronous space vibration in simultaneous tension, torsion, bending and shear. Hysteretic and viscous dampings of the beam material and ambient medium are considered. Four new generalized complex Kolousek functions are derived. A 6 × 6 complex symmetric stiffness matrix is established for a semi-infinite beam member excited at its end by prescribed harmonic translations and rotations which have the same frequency but may be out of phase. This matrix extends the range of application of the so called ‘exact analysis’ of non-proportionally damped built-up beam structures as described in a previous paper by Lundén and Åkesson.1 Numerical examples are given, including applications of the computer program SFVIBAT-DAMP. Power flows are studied. 相似文献
108.
Dry-formed networks of cellulose fibers, produced with a laboratory device, have been impregnated with aqueous solutions of poly(vinyl alcohol) or solutions of poly(vinyl acetate) in acetone. In both cases, the strength and stiffness of the networks increase several times compared with the unmodified structure. When aqueous solutions are used, it appears that a minimum amount of poly(vinyl alcohol) is required (ca. 2 wt %) to increase the strength appreciably, but when poly(vinyl acetate) dissolved in acetone is used, as a binder, the strength improves even at the lowest level of polymer addition. For the systems studied here, the elongation at rupture increased with increasing polymer concentration. In most cases, the amount of polymer in the network structure was less than 10 wt %. Some results from impregnations using other polymeric systems, e.g., latices, are also reported. 相似文献
109.
Defocused speckle correlation is introduced as a tool for measuring the response in metal sheets during percussion laser drilling. For this procedure the fourth-harmonic Nd:YAG wavelength (266 nm) was used in pulsed mode. The method provides a cost-efficient and robust alternative to speckle interferometry for the study of the small deformations that appear during laser processing. The accuracy was shown to be of the order of a few tens of microradians for the tilt component that is measured, which translates to a few nanometers in deflection when the component is spatially integrated. In the measurements, deflections in the form of craters as large as 50 nm were detected on the back sides of silver and copper sheets. The diameters of the craters were 300 microm in the silver and 150 microm in the copper sheet; the output diameter of the hole was -5 microm. 相似文献
110.
Almqvist M Törndahl M Nilsson M Lilliehorn T 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》2005,52(12):2298-2302
This paper demonstrates that light diffraction tomography can be used to measure the acoustic field of micromachined ultrasonic transducers (MUT) in cases in which standard methods like hydrophone and microphone measurements fail. Two types of MUTs have been characterized with the method, one air-coupled capacitive MUT (cMUT) and one waterloaded continuous wave (CW) miniature multilayer lead zirconate titanate (PZT) transducer. Light diffraction tomography is an ultrasound measurement method with some special characteristics. Based on the interaction of light and ultrasound, it combines light intensity measurements with tomography algorithms to produce a measurement system. The method offers nonperturbing pressure measurements with high spatial resolution. It has been shown that, under certain circumstances, light diffraction tomography can be used as an absolute pressure measurement method with accuracy in the order of 10% in water and 13% in air. The results show that air-coupled cMUTs in the frequency range of about 1 MHz as well as the extreme near field of a miniaturized CW 10 MHz water-loaded transducer were successfully characterized with light diffraction tomography. 相似文献