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71.
A gas chromatographic-mass spectrometric method was used to separate quinine and its metabolites present in urine after oral dosing of 300 mg quinine in humans. The technique allowed the separation of quinine and ten metabolites. Four of these metabolites were definitely identified as 3-hydroxyquinine, 2'-quinone, O-desmethylquinine and 10,11-dihydroxydihydroquinine, by comparing their methane chemical ionization mass spectra with those of authentic standards prepared by organic synthesis. Six other metabolites are described for the first time in human urine. From their electron impact and chemical ionization mass spectra, we propose these compounds to be 3-hydroxy-2'-quinone, O-desmethyl-2'-quinone, O-desmethyl-3-hydroxyquinine, O-desmethyl-3-hydroxy-2'-quinone, 10,11-dihydroxydihydro-2'-quinone and 10,11-dihydroxydihydro-O-desmethylquinine. These secondary metabolites probably arose from further biotransformation of the four primary metabolites.  相似文献   
72.
Coupling sensors in a sensor network with mobility mechanism can boost the performance of wireless sensor networks (WSNs). In this paper, we address the problem of self-deploying mobile sensors to reach high coverage. The problem is modeled as a multi-objective optimization that simultaneously minimizes two contradictory parameters; the total sensor moving distance and the total uncovered area. In order to resolve the aforementioned deployment problem, this study investigates the use of biologically inspired mechanisms, including evolutionary algorithms and swarm intelligence, with their state-of-the-art algorithms. Unlike most of the existing works, the coverage parameter is expressed as a probabilistic inference model due to uncertainty in sensor readings. To the best of our knowledge, probabilistic coverage of mobile sensor networks has not been addressed in the context of multi-objective bio-inspired algorithms. Performance evaluations on deployment quality and deployment cost are measured and analyzed through extensive simulations, showing the effectiveness of each algorithm under the developed objective functions. Simulations reveal that only one multi-objective evolutionary algorithm; the so-called multi-objective evolutionary algorithm with decomposition survives to effectively tackle the probabilistic coverage deployment problem. It gathers more than 78 % signals from all of the targets (and in some cases reaches 100 % certainty). On the other hand, non-dominated sorting genetic algorithm II, multi-objective particle swarm optimization, and non-dominated sorting particle swarm optimization show inferior performance down to 16–32 %, necessitating further modifications in their internal mechanisms.  相似文献   
73.
This work details the study, development, and experimental implementation of GPS aided strapdown inertial navigation system (INS) using commercial off-the-shelf low-cost inertial measurement unit (IMU). The data provided by the inertial navigation mechanization is fused with GPS measurements using loosely-coupled linear Kalman filter implemented with the aid of MPC555 microcontroller. The accuracy of the estimation when utilizing a low-cost inertial navigation system (INS) is limited by the accuracy of the sensors used and the mathematical modeling of INS and the aiding sensors’ errors. Therefore, the IMU data is fused with the GPS data to increase the accuracy of the integrated GPS/IMU system. The equations required for the local geographic frame mechanization are derived. The direction cosine matrix approach is selected to compute orientation angles and the unified mathematical framework is chosen for position/velocity algorithm computations. This selection resulted in significant reduction in mechanization errors. It is shown that the constructed GPS/IMU system is successfully implemented with an accurate and reliable performance.  相似文献   
74.
In six normal volunteers hyperprolactinemia was induced by sulpiride (150 mg/day) for 10 days. Both before and during sulpiride hCG was injected; the higher testosterone response to hCG, when PRL levels were enhanced, suggests a possible stimulatory role of PRL on Leydig cells.  相似文献   
75.
Injured cortical arteries were observed by electron microscopy. Haemostasis was brought about by both platelets and fibrin, but the intravascular thrombus contained only platelets. Some platelets adhered to the exposed subendothelium but did not form a continuous layer. Such platelet adhesion does not provoke a thrombus, which appears only at the opening in the artery. There was a gap of 7 micrometers between the thrombus and the intact arterial wall. The thrombus was built up progressively by concentric accumulation around the main injury. Central platelets were closely packed and the more distal ones loosely gathered but not touching and not activated. This structure was very different from that observed in in vitro aggregates which formed rapidly and whose platelets are all at the same stage of development and disposed radially. This implies a different sequence in the physiological evolution of platelets submitted to either mode of activation. The results obtained with the present model differ in several respects from those obtained with other models.  相似文献   
76.
Ultrasonic velocity and isoentropic compressibility measurements are reported on aqueous solutions of polyethylenoxide of different molecular weights and different concentrations using pulsed ultrasonic apparatus operating at 2 MHz and 310 K. The data obtained as a function of concentration indicate the magnitude of the contribution due to relaxation of the backbone of the ethylene group. The results show a linear increase of density, velocity and viscosity values with increasing molecular weight and concentration of PEO. In contrast, the isoentropic compressibility decreases with increasing of molecular weight and concentration of PEO. A mathematical equation correlating isoentropic compressibility and molecular weight of the polymer is suggested. This was applied to the calculation of the molecular weight of unknown samples of PEO from their measured isoentropic compressibility; the results obtained agreed well with those obtained from osmometry.  相似文献   
77.
78.
To achieve the exponential rates of convergence possible with the p-version finite element method requires properly constructed meshes. In the case of piecewise smooth domains, these meshes are characterized by having large curved elements over smooth portions of the domain and geometrically graded curved elements to isolate the edge and vertex singularities that are of interest. This paper presents a procedure under development for the automatic generation of such meshes for general three-dimensional domains defined in solid modeling systems. Two key steps in the procedure are the determination of the singular model edges and vertices, and the creation of geometrically graded elements around those entities. The other key step is the use of general curved element mesh modification procedures to correct any invalid elements created by the curving of mesh entities on the model boundary, which is required to ensure a properly geometric approximation of the domain. Example meshes are included to demonstrate the features of the procedure.
Mark W. BeallEmail:
  相似文献   
79.
Cytogenetic approaches play an essential role as a quick evaluation of the first genetic effects after mutagenic treatment. Although labor-intensive and time-consuming, they are essential for the analyses of cytotoxic and genotoxic effects in mutagenesis and environmental monitoring. Over the years, conventional cytogenetic analyses were a part of routine laboratory testing in plant genotoxicity. Among the methods that are used to study genotoxicity in plants, the micronucleus test particularly represents a significant force. Currently, cytogenetic techniques go beyond the simple detection of chromosome aberrations. The intensive development of molecular biology and the significantly improved microscopic visualization and evaluation methods constituted significant support to traditional cytogenetics. Over the past years, distinct approaches have allowed an understanding the mechanisms of formation, structure, and genetic activity of the micronuclei. Although there are many studies on this topic in humans and animals, knowledge in plants is significantly limited. This article provides a comprehensive overview of the current knowledge on micronuclei characteristics in plants. We pay particular attention to how the recent contemporary achievements have influenced the understanding of micronuclei in plant cells. Together with the current progress, we present the latest applications of the micronucleus test in mutagenesis and assess the state of the environment.  相似文献   
80.
In this paper, a two dimensional laminar liquid film which condenses on a vertical microchannel is investigated analytically. A liquid film thickness, condensation mass flux flow and the variation of the velocity through the liquid thickness were determined by modified Navier–Stockes and energy equations. The effect of some parameters on the liquid film thickness, condensation mass flow rate and velocity are investigated. These parameters include slipping in temperature, β, and velocity, α, due to microscale interaction. It was found that, the liquid film thickness, δ, decreases as the slipping factors increases, and diminishes as a value of slipping factors (α and β) become more than or equal to 0.1. Increasing the slip in temperature due to microscale interaction causes the condensation mass flow rate to increase as the value of slip in velocity increases. Additionally, the slip value in the channel was found to increase as the slip value in velocity, α, increases.  相似文献   
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