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81.
Abstract To study the behaviour of anisotropic media in reflection when illuminated by natural light, an ‘indicating surface of natural reflectance’ is defined. The use of such a surface is proposed, and its statistical parameters are given. The expressions that relate these parameters to the refractive indices of the incident medium and to the principal indices of the medium under observation have been deduced for the case of uniaxial media. Those corresponding to uniaxial transparent substances are presented here. 相似文献
82.
Sixto Malato Julin Blanco Alfonso Vidal Diego Alarcn Manuel I. Maldonado Julia Cceres Wolfgang Gernjak 《Solar Energy》2003,75(4):329-336
The technical feasibility and performance of photocatalytic degradation of four water-soluble pesticides (diuron, imidacloprid, formetanate and methomyl) have been studied at pilot scale in two well-defined systems which are of special interest because natural-solar UV light can be used for them: heterogeneous photocatalysis with titanium dioxide and homogeneous photocatalysis by photo-Fenton. The pilot plant is made up of compound parabolic collectors specially designed for solar photocatalytic applications. The initial concentration tested with imidacloprid, formetanate and methomyl was 50 and 30 mg/l with diuron, and the catalyst concentrations were 200 mg/l and 0.05 mM with TiO2 and iron, respectively. Total disappearance of the parent compounds, 90% mineralisation and toxicity reduction below the threshold (EC50) have been attained with all pesticides tested. All these results have contributed to an evaluation of photocatalytic treatment capacity and comments on the main parameters of TiO2 and Fe separation from the treated water. 相似文献
83.
Alfonso Centuori 《电子产品世界》2005,(23):123-124
可再充电电池常常被用来为诸如数码相机、PDA、移动电话和MP3播放机等便携式设备供电. 相似文献
84.
Maria Ariza-Avidad Alejandra Nieto Alfonso Salinas-Castillo Luis F Capitan-Vallvey Gordon M Miskelly Michael J Sailor 《Nanoscale research letters》2014,9(1):410
We report the monitoring of porous silicon (pSi) degradation in aqueous solutions using a consumer-grade digital camera. To facilitate optical monitoring, the pSi samples were prepared as one-dimensional photonic crystals (rugate filters) by electrochemical etching of highly doped p-type Si wafers using a periodic etch waveform. Two pSi formulations, representing chemistries relevant for self-reporting drug delivery applications, were tested: freshly etched pSi (fpSi) and fpSi coated with the biodegradable polymer chitosan (pSi-ch). Accelerated degradation of the samples in an ethanol-containing pH 10 aqueous basic buffer was monitored in situ by digital imaging with a consumer-grade digital camera with simultaneous optical reflectance spectrophotometric point measurements. As the nanostructured porous silicon matrix dissolved, a hypsochromic shift in the wavelength of the rugate reflectance peak resulted in visible color changes from red to green. While the H coordinate in the hue, saturation, and value (HSV) color space calculated using the as-acquired photographs was a good monitor of degradation at short times (t < 100 min), it was not a useful monitor of sample degradation at longer times since it was influenced by reflections of the broad spectral output of the lamp as well as from the narrow rugate reflectance band. A monotonic relationship was observed between the wavelength of the rugate reflectance peak and an H parameter value calculated from the average red-green-blue (RGB) values of each image by first independently normalizing each channel (R, G, and B) using their maximum and minimum value over the time course of the degradation process. Spectrophotometric measurements and digital image analysis using this H parameter gave consistent relative stabilities of the samples as fpSi > pSi-ch. 相似文献
85.
Enrique Castillo Alfonso Fernández-Canteli Dieter Siegele 《International Journal of Fracture》2014,187(1):159-172
A crack growth model that allows us to obtain the S–N curves from the crack growth rate curves is presented in an attempt to harmonize the stress based and fracture mechanics approaches in lifetime prediction of long cracks propagation. First, using the Buckingham theorem, the crack growth rate curve $\frac{da}{dN}-\varDelta K$ is defined over all its range as a cumulative distribution function based on a normalized dimensionless stress intensity factor range $\varDelta K^+$ . Then, a relevant theorem is derived that provides an alternative to self-similarity allowing significant reduction of experimental planning. In this way, different $a-N$ crack growth curves for different stress ranges $\varDelta \sigma $ and initial crack lengths $a_0$ can be obtained from a particular crack growth curve under some conditions. The S–N field is obtained from the crack growth curves, showing the close relation between the fracture mechanics and stress approaches. Finally, the model is applied to a particular set of experimental data to obtain the crack growth rate curve and the S–N curves of a certain material for a subsequent fatigue lifetime assessment 相似文献
86.
Montella A Aria M D'Ambrosio A Galante F Mauriello F Pernetti M 《Accident; analysis and prevention》2011,43(6):2072-2084
Aim of the study was to investigate, by means of a driving simulator experiment, drivers’ behaviour in terms of speed, deceleration, and lateral position on major approaches of rural intersections in relation to different perceptual cues.In the experiment, ten different design conditions with and without speed-reducing treatments along the approach to the intersection were tested. Twenty-three drivers drove a test route two times and data from the second drive were used for comparison. The order of the ten design conditions was counterbalanced for all the drivers to minimize the presentation order effect. Three different data analysis techniques were used: (a) cluster analysis of speed and lateral position data, (b) statistical tests of speed and lateral position data, and (c) categorical analysis of deceleration behaviour patterns.The most effective treatments were the dragon teeth markings (based on the principle of optical road narrowing), the colored intersection area (based on the principle of intersection highlighting), and the raised median island (based on the principle of physical road narrowing). These measures, in comparison to the base intersection, produced: (1) a significant speed reduction starting from 250 m before the intersection in the range between 13 and 23 km/h, (2) a significant change in the deceleration behaviour with a reduction in the proportion of drivers which did not decelerate, and (3) a shift away from the intersection of the deceleration beginning. Given the significant effects on drivers’ behaviour, the dragon teeth markings, the colored intersection area, and the raised median island are strongly recommended for real world implementation. 相似文献
87.
Otero P Alfonso A Alfonso C Rodríguez P Vieytes MR Botana LM 《Analytical chemistry》2011,83(15):5903-5911
Chromatographic techniques coupled to mass spectrometry is the method of choice to replace the mouse bioassay (MBA) to detect marine toxins. This paper evaluates the influence of different parameters such as toxin solvents, mass spectrometric detection method, mobile-phase-solvent brands and equipment on okadaic acid (OA), dinophysistoxin-1 (DTX-1), and dinophysistoxin-2 (DTX-2) quantification. In addition, the study compares the results obtained when a toxin is quantified against its own calibration curve and with the calibration curve of the other analogues. The experiments were performed by liquid chromatography (LC) and ultraperformance liquid chromatography (UPLC) with tandem mass spectrometry detection (MS/MS). Three acetonitrile brands and two toxin solvents were employed, and three mass spectrometry detection methods were checked. One method that contains the transitions for azaspiracid-1 (AZA-1), azaspiracid-2 (AZA-2), azaspiracid-3(AZA-3), gimnodimine (GYM), 13-desmethyl spirolide C (SPX-1), pectenotoxin-2 (PTX-2), OA, DTX-1, DTX-2, yessotoxin (YTX), homoYTX, and 45-OH-YTX was compared in both instruments. This method operated in simultaneous positive and negative ionization mode. The other two mass methods operated only in negative ionization mode, one contains transitions to detect DTX-1, OA DTX-2, YTX, homoYTX, and 45-OH-YTX and the other only the transitions for the toxins under study OA, DTX-1, and DTX-2. With dependence on the equipment and mobile phase used, the amount of toxin quantified can be overestimated or underestimated, up to 44% for OA, 46% for DTX-1, and 48% for DTX-2. In addition, when a toxin was quantified using the calibration curve of the other analogues, the toxin amount obtained is different. The maximum variability was obtained when DTX-2 was quantified using either OA or a DTX-1 calibration curve. In this case, the overestimation was up to 88% using the OA calibration curve and up to 204% using the DTX-1 calibration curve. In summary, the correct quantification of DSP toxins by MS detection depends on multiple factors. Since these factors are not taken into account in a validated protocol, these results question the convenience of having MS/MS as a reference method for protecting consumers of marine toxins, moreover if toxicity of each group is considered independently and total toxicity is not summed anymore as it is in the MBA. 相似文献
88.
何谓永恒城市与火车之间的爱恨情仇/关系源远流长,有过激情四溢的乐章,也有过痛苦折磨的片断,有过甜蜜美好的瞬间,也有公诸于众的背叛。而今,两者之间的关系历经变化,今非昔比。然而在巴伦西亚的杰昆·索罗拉火车站,城市与火车之间的激情烈焰仍在燃烧。新车站在允许高速火车进行停靠的同时,完成了将铁轨迁入地下的工程: 相似文献
89.
Federico González María-Elena Villafuerte-Castrejón Alfonso Huanosta 《Journal of Electroceramics》2007,18(3-4):323-327
A Pb0.98Eu0.02(ZryTi1−y
)0.995O3 compound series, with y = 0.60, 0.53 and 0.45 was prepared. PZT samples were synthesized by sol–gel technique. The crystallization and quality of
the compounds were analyzed by powder X-ray diffraction and electron microscopy. The shape of the ε′(ω) vs T curves can be considered typical of a ferro-paraelectric transition. The ferro-paraelectric transition temperature
for each composition was 348, 328 and 307°C, for the y = 0.45, 0.53 and 0.60, respectively. σ′(ω) is strongly influenced by short range processes. For the logσ′(ω) curves as function of temperature, there is evidence of a non dispersive dc-conductivity component for the high temperature
region. The associated dc-activation energies are larger than those calculated for the ac region (at lower temperatures). 相似文献
90.
Iñigo Navarro Antonio J. López-Martín Carlos A. de la Cruz Alfonso Carlosena 《Analog Integrated Circuits and Signal Processing》2004,41(2-3):159-166
A compact, four-quadrant analog CMOS multiplier featuring wide dynamic range is presented. The capacitive voltage division obtained by the use of Floating-Gate MOS (FGMOS) transistors, and an accurate wide-swing current mirror based on active bootstrapping, allow a wide input range, low harmonic distortion, and high linearity. Simulation and measurement results for a 0.8 μm CMOS prototype demonstrate the validity of the proposed approach. 相似文献