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71.
In the presence of defocusing the modified Sparrow limits of resolution for two-line objects have been investigated for a diffraction-limited coherent optical system apodized by generalized Hanning amplitude filters. These limits have been studied as a function of different parameters such as intensity ratio, the order of the filter for various amounts of apodization parameter. Results reveal that in some situations the defocusing is effective in enhancing the resolution of an optical system.  相似文献   
72.
CSTR (Continuous stirred tank reactor) is employed in process control and chemical industries to improve response characteristics and system efficiency. It has a highly nonlinear characteristic that includes complexities in its control and design. Dynamic performance is compassionate to change in system parameters which need more effort for planning a significant controller for CSTR. The reactor temperature changes in either direction from the defined reference value. It is important to note that the intensity of chemical actions inside the CSTR is dependent on the various levels of temperature, and deviation from reference values may cause degradation of biomass quality. Design and implementation of an appropriate adaptive controller for such a nonlinear system are essential. In this paper, a conventional Proportional Integral Derivative (PID) controller is designed. The conventional techniques to deal with constraints suffer severe limitations like it has fixed controller parameters. Hence, A novel method is applied for computing the PID controller parameters using a swarm algorithm that overcomes the conventional controller's limitation. In the proposed technique, PID parameters are tuned by Particle Swarm Optimization (PSO). It is not easy to choose the suitable objective function to design a PID controller using PSO to get an optimal response. In this article, a multi-objective function is proposed for PSO based controller design of CSTR.  相似文献   
73.
Das S  Englefield CG  Goud PA 《Applied optics》1985,24(15):2323-2334
Theoretical and experimental investigations are described for determining the transmission characteristics of a multimode fiber with microbending for coherent and partially coherent illumination. The measured values of the average excess power loss are shown to be in close agreement with the theory. Also, an estimate of the excess transient loss due to mode coupling is found to be in good agreement with previously published data. Mode-mode interference is shown to be the cause of temporal fluctuations in the microbending loss, from which expressions for modal noise and baseband/subcarrier nonlinearity are derived on a statistical basis. For a given overall loss, the results show that many uniformly distributed small amplitude microbends cause much less modal noise and distortion than a few large amplitude microbends.  相似文献   
74.
Biomass represents the renewable energy source and their use reduces the consumption of fossil fuels and limits the emission of CO2, SOx, NOx and heavy metals. They are used in pyrolysis, gasification, combustion and co-combustion. Present study aims to highlight the common biomass available in Canada such as wheat straw, barley straw, flax straw, timothy grass and pinewood. The biomass samples were collected form Saskatoon, Canada and examined for their physical and chemical characteristics using static bomb calorimeter, XRD, TGA, ICP-MS, CHNSO, FT-IR and FT-NIR. The biomass samples were subjected to three-step extraction process, i.e. hexane, alcohol and water extraction separately, after extraction the raffinate biomass was acid hydrolyzed. The acid soluble fractions, which mainly contained degraded sugars, were analysed by HPLC and the lignin content was determined using acid insoluble fraction. The hexane extract (i.e. waxes), alcohol extract and lignin were characterized by FT-IR spectroscopy. Among all the biomass samples pinewood shows lower ash and lignin content, while shows higher calorific value, cellulose and hemicellulose content. The appreciable amount of hexane soluble in pinewood was due to the presence of terpene hydrocarbons. However among the agricultural biomass samples barley straw shows higher ash, wax and lignin content compared to wheat and flax straw. All these properties combined together have shown that pinewood, wheat and flax can act as the potential candidates for bio-energy production.  相似文献   
75.
Recent Developments in Microencapsulation of Food Ingredients   总被引:9,自引:0,他引:9  
Microencapsulation involves the incorporation of food ingredients, enzymes, cells, or other materials in small capsules. Microcapsules offer food processors a means with which to protect sensitive food components, ensure against nutritional loss, utilize otherwise sensitive ingredients, incorporate unusual or time-release mechanisms into the formulation, mask or preserve flavors and aromas, and transform liquids into easily handled solid ingredients. Various techniques are employed to form microcapsules, including spray drying, spray chilling or spray cooling, extrusion coating, fluidized-bed coating, liposome entrapment, coacervation, inclusion complexation, centrifugal extrusion, and rotational suspension separation. Recent developments in each of these techniques are discussed in this review. Controlled release of food ingredients at the right place and the right time is a key functionality that can be provided by microencapsulation. A timely and targeted release improves the effectiveness of food additives, broadens the application range of food ingredients, and ensures optimal dosage, thereby improving the cost effectiveness for the food manufacturer. Reactive, sensitive, or volatile additives (vitamins, cultures, flavors, etc.) can be turned into stable ingredients through microencapsulation. With carefully fine-tuned controlled-release properties, microencapsulation is no longer just an added-value technique, but the source of totally new ingredients with matchless properties.  相似文献   
76.
OBJECTIVE: To determine whether pituitary down-regulation after gonadotropin-releasing hormone analogue (GnRH-a) administration can be accurately predicted by transvaginal ultrasonographic measurement of endometrial thickness. DESIGN: Prospective study. SETTING: An IVF unit of an academic medical center. PATIENT(S): One hundred eighty-one patients undergoing 265 IVF-ET treatment cycles using GnRH-a in the long protocol. MAIN OUTCOME MEASURE(S): Serum concentrations of E2 were determined, and endometrial thickness was measured by transvaginal sonography. The accuracy of endometrial thickness for predicting pituitary down-regulation was calculated. RESULT(S): Pituitary down-regulation, defined as a serum E2 concentration of < or = 55 pg/mL, was achieved in 77% (204 of 265) of the cycles. An endometrial thickness of < or = 6 mm was found in 92.2% (188 of 204) of cycles in which down-regulation was achieved. An estradiol level of < or = 55 pg/mL was present in 95.9% (188 of 196) of cycles with endometrial thickness of < or = 6 mm. CONCLUSION(S): A state of relative hypoestrogenism after GnRH-a administration, indicative of pituitary down-regulation, can be predicted with a high degree of accuracy by ultrasonographic measurement of endometrial thickness. Thus, routine testing for serum E2 concentration may be safely omitted. This may allow further simplification of IVF protocols and increase both cost-effectiveness and patients' convenience.  相似文献   
77.
Javed  A. Goud  P.A. 《Electronics letters》1976,12(16):399-400
A useful technique is presented for evaluating the crossmodulation of IMPATT-diode amplifiers. This technique uses Volterra series to represent the frequency-dependent nonlinear behaviour of impatt diodes. A numerical example is given.  相似文献   
78.
Owing to severe allergic reactions (anaphylaxis) and resistance exhibited by sulfonamide-based carbonic anhydrase (CA) inhibitors, non-classical or non-sulfonamide CA inhibitors are gaining increased attention by medicinal chemists. In this context, we report the design and synthesis of 30 new non-sulfonamide sulfocoumarin derivatives as CA inhibitors. They were investigated against hCA I and II (cytosolic isozymes) as well as hCA IX and XII (transmembrane, tumor-associated enzymes). All compounds showed prominent selectivity for the tumor-associated isoenzymes hCA IX and XII over the cytosolic isoenzymes hCA I and II. Among all synthesized compounds, 1-(2,2-dioxidobenzo[e][1,2]oxathiin-6-yl)-3-(o-tolyl)urea( 5 j )and1-(3-fluorophenyl)-3-(8-methoxy-2,2-dioxidobenzo[e][1,2]oxathiin-6-yl)urea( 5 q )were found to be more potent and to have better inhibition constant values against hCA IX than the standard acetazolamide (AAZ), with Ki values of 23.6 and 23.3 nM, respectively. All other compounds were found to be active under Ki=920 nM against hCA IX and XII.This study provides a new perspective for the future development of non-sulfonamide derivatives as selective CA inhibitors.  相似文献   
79.
The present study deals with the implications of non-Newtonian fluid via a slanted parabolic started surface with ramped energy. In addition, the characteristics of electrically conducting viscoelastic liquid moving across the Riga surface are investigated systematically, emphasized within the time-dependent concentration and temperature variations. The mathematical model is made possible by enforcing momentum and heat conservation principles in the format of partial differential equations (PDEs). Heat considerations are emphasized with respect to radiant heat influx. Similarity characteristics are leveraged to convert PDEs to ordinary differential equations. The Laplace transform method is used to find the exact solutions for the obtained differential configuration. The effect of flow on associated patterns is depicted graphically and with tables. Furthermore, fluctuation in relevant engineering parameters such as wall shear stress, temperature, and mass variability on the surface is measured. The range of parameters selected is as follows: ψ[0.1-1] $\psi [0.1 \mbox{-} 1]$, Pr[0.71-10] $Pr[0.71 \mbox{-} 10]$, Sc[0.16-2.01] $Sc[0.16 \mbox{-} 2.01]$, Gr=Gc[5-20] $Gr=Gc[5 \mbox{-} 20]$, E[1-5] $E[1 \mbox{-} 5]$, and R[2-10] $R[2 \mbox{-} 10]$. The analytical and numerical solutions are validated and in good agreement. It is worth reporting that the improved Hartmann number and thermal radiation values boost velocity dispersion and skin friction. As expected, respectively, energy and mass transfer rates are escalated with large values of Prandtl number and Schmidt number.  相似文献   
80.
A network of wireless sensors is a self-infrastructure approach with many sensory nodes. The distributed sensory nodes communicate with each other via sensory points. In wireless sensor network (WSN), the sensory nodes collect information for healthcare, military and monitoring systems. Such networks require an exclusive arrangement of the nodes to challenge inherent limitations and energy deficiency. The conventional design of a communication system consumes more energy with high latency causing degraded performance. This study provided a machine learning-based path optimization mechanism using the least energy resources in designing an effective wireless network system with enhanced three measures of network performance, including throughput, packet delivery efficiency and energy usage. The proposed methodology is validated through network simulation tools.  相似文献   
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