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131.
The reaction of methane-derived coke (CHx: intermediate of the reforming reaction and also a source of coke deposition) with CO2 was studied on supported Pt catalysts in relation with CO2 reforming of methane. Temperature-programmed hydrogenation (TPH) was performed to investigate the reactivity of coke deposition after the catalyst was exposed to CH4/He at 1070 K. Coke on Pt/Al2O3 could be hydrogenated around 873 K, while for Pt/ZrO2 this was above 1073 K. The results indicate that the reactivity of coke with hydrogen was higher on Pt/Al2O3 than on Pt/ZrO2, which was different from the reactivity of coke towards CO2. Thus, the reactivity of CO2 was studied and compared on these catalysts by several technics. The amount of CO evolution was measured during CO2 flow at 1070 and 875 K. Rate and amount of converted CO2 were higher on Pt/ZrO2 than on Pt/Al2O3. Pt/ZrO2 was proven to react with CO2 to produce CO and active oxygen (CO2CO+O) (probably on its oxygen defect site) more easily than Pt/Al2O3.  相似文献   
132.
The kinetics of lipase-catalyzed interesterification of triglycerides and fatty acids in organic media was studied. First, the lipase Saiken 100,Rhizopus japonicus, was modified by surfactant to form an enzyme precipitate in aqueous solution, which was well dispersed in organic solvents. This modified lipase catalyzed the interesterification of tripalmitin and stearic acid. The enzyme has 1,3-positional specificity and does not distinguish between stearic and palmitic acids. The kinetic model developed to describe the interesterification reaction system is based on mass balance of two consecutive second-order reversible reactions. The reaction rate constant, k, was determined by solving the differential rate equations of the reaction system and by expressing the value of k as a function of concentrations of the substrates with time. The model gave satisfactory results. The best value of the specific reaction rate constant k* that fits all experimental data was 1.2 · 10−5 [L2/(mmol · mg biocatalyst · h)] under the reaction conditions in this study.  相似文献   
133.
The idea of an activation complex is popular for explaining reaction rates, but the characteristics of reactions and catalysis may not be explained in this way. A predestined state for each reaction composed of surface atoms and adsorbed species is responsible for these features. Two single Sn atoms trapped in adjacent half-unit cells of an Si(111) 7 × 7 surface is an example of a predestined state. An isolated Sn atom in a half-unit cell does not migrate to other half-unit cells at room temperature, but when two single Sn atoms are in adjacent half-unit cells they undergo rapid combination to form an Sn2 dimer. In addition, these two single Sn atoms replace the center Si adatoms and an Si4 cluster is formed. The spatial distribution of molecules desorbing from surfaces may reflect the predestined states for the desorption processes. The spatial distribution in the temperature-programmed desorption (TPD) of NO on Pd(110) and Pd(211) surfaces and that in the temperature-programmed reaction (TPR) of NO + H2 were studied. N2 desorbing from Pd(110) by the recombination of N atoms obeys cos6 – cos7 but the N2 produced by a catalytic reaction of NO with H2 obeys cos. In contrast, the N2 desorbing with NO at 490 K in the TPD of Pd(110) shows a sharp off-normal distribution expressed by cos46( – 38). The adsorption of NO on Pd(211) predominantly occurs on the (111) terrace but the spatial distribution suggests that the predestined states for the reaction and desorption are formed on both the (111) terrace and (100) step surfaces.  相似文献   
134.
Resin-matrix composites dispersing low-loss dielectric ceramic filler have received a considerable interest for high-frequency application, because of their good shape flexibility and controllable dielectric properties. In this study, (Ba,Sr)TiO3-type ceramic particles have been synthesized by KCl molten salt method to serve as filler particle for resin-matrix dielectric composite. Dielectric measurement confirmed that the composite fabricated by tape-casting demonstrated two times higher dielectric constant of 50.4 than the other composites fabricated by direct-casting using a metal mold. Pore-size distribution as well as ceramic filler content was strongly correlated with the formation of electrical flux in the composites to enhance dielectric constant.  相似文献   
135.
In this paper, we focus on relationship between the rope and fingers to implement a knot and estimate error occurred during execution of knotting task. In the previous work, the authors have proposed a method for making various knots from synthesis of basic operations called skills that are derived from analyzing the knotting processes. Each individual skill has an operation to handle the rope and conditions for executing and completing the task skill. By combining these skills, we can make the whole knotting process robust. In this paper, the ‘relations’, which describe the positions of the rope relative to the fingers, found from the successful cases, using the teaching data, were defined as the conditions of the task skills. Relation of rope and fingers at a specific state is presented by using propositional variables and logical connectives. Knotting skills were constructed to be executed robustly using the detected conditions. Occurrence of an error is estimated by finding out an abnormal relation. In this case, a corrective action can be inserted to modify the position of contact points, which are relative to the unsatisfied conditions to satisfy the detected conditions; therefore, skill execution is more reliable. We confirm the effectiveness of the methods through experiments.  相似文献   
136.
ABSTRACT

In a fuel handling system of sodium-cooled fast reactors (SFRs), it is necessary to remove the sodium remaining on spent fuel assemblies (FAs) before storing them in a spent fuel water pool (SFP). A next-generation SFR in Japan has adopted an advanced dry-cleaning system that consists of argon gas blowing to remove the metallic residual sodium on the FA, which increases economic competitiveness and reduces waste products thanks to a waterless process. In this R&D work, the performance of the dry cleaning process has been investigated.

This paper describes experimental and analytical studies focusing on the amount of residual sodium remaining on a fuel pin bundle before and after the argon gas blowing process. The experiments were conducted using a sodium test loop and a short (approximately 1 m) specimen consisting of a 7-pin bundle. The effects of the blowing gas velocity and the blowing time were quantitatively analyzed in the experiments. The blowing gas velocity was varied from 3.9 to 31.3 m/s, and 113 data-points of the residual sodium were collected during the experiment. On the basis of these experimental results, the residual sodium quantification method for the fuel pin bundle was constructed.  相似文献   
137.
Series of RMn2O5 (R = Sm-Lu, Bi, Y) are simultaneously ferroelectric and antiferromagnetic at low temperatures. The ferroelectric Curie temperature (TCE = 25–40 K) is slightly lower than the antiferromagnetic Néel temperature (TN = ~45 K), implying that the ferroelectricity is induced with the antiferromagnetic long-range order in RMn2O5. Previously, we have investigated the thermal expansion anomaly in YMn2O5 at higher temperatures than TN = 45 K, which would be the precursor phenomenon relating to the ferroelectric transition. This study tries to investigate a further detailed precursor phenomenon to make clear the origin of the ferroelectricity in YMn2O5. Particularly, we focus on the temperature factors of each cation in the temperature range from 50 K to 170 K. The single crystal X-ray diffraction of YMn2O5 was integrated at 298 K and 112 K by using a single crystal diffractometer with an imaging plate. The structural parameters were well refined as Pbam at both temperatures. In the refined result, it was found that the thermal ellipsoid became more anisotropic for the Mn or the Y ions with decreasing temperature from 298 K to 112 K. In addition, the long principal axis of the thermal ellipsoids rotated in the ab plane with decrease of temperature. At 112 K, the long principal axis of Mn3+ thermal ellipsoid in ab plane is almost parallel to the direction from the apex to the base of the pyramid square. The direction agrees with a possible ionic displacement speculated from the irreducible representation analysis.  相似文献   
138.
Technologies for narrow-channel effect suppression in photodiodes (PDs) and vertical CCDs (V-CCDs) and for smear reduction in PDs have been developed in order to improve dynamic range in small pixel interline-transfer CCD (IT-CCD) image sensors. The new technologies have been applied to a progressive-scan IT-CCD image sensor with 5 μm square pixels and have (1) increased the charge handling capability of its V-CCDs to 4500 electrons/V; (2) improved its smear value to -95 dB; and (3) increased the saturation charge of its PDs to 2.3×104 electrons  相似文献   
139.
140.
A new convenient calcium cyanamide (CaCN2) reduction route was developed to synthesize the Eu2 activated Ca-α-SiAlON phosphors containing low oxygen content. The luminescence properties of the obtained products were investigated for white LEDs application. The critical Eu2 concentration in various hosts and its effect on the photoluminescence properties were studied. The optimized sample (10at.% Eu2 vs. Ca2 ) could be efficiently excited by the current GaN/InGaN blue LED chips and provided emission intensity competitive with that of YAG:Ce3 (P46-Y3) standard, revealing that this phosphor was a potential candidate for phosphor-converted white LEDs.  相似文献   
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