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排序方式: 共有149条查询结果,搜索用时 140 毫秒
1.
A 1 GHz CMOS analog front-end for general partial response maximum likelihood (GPRML) read channel in hard disk drive application has been implemented in 0.35 /spl mu/m CMOS. A continuous time analog filter fulfills the relaxed equalization for GPRML detection and can save up to 35% power consumption for the whole read channel. An analog DFE-based timing recovery loop is implemented to avoid the extremely long latency in the digital signal processing path (Viterbi decoder). The measured performances is 1.1 dB off simulations at 800 MHz and 1.6 dB off at 1GHz. The chip draws 240 mW from a 3.3 V supply at 800MHz clock and 380 mW from a 3.6 V supply at 1 GHz clock.  相似文献   
2.
A highly selective and linear switched-capacitor channel-select filter is fabricated in 1-μm CMOS for a direct-conversion wireless receiver operating in the 902-928 MHz ISM band. The filter selects a 230-kHz wide channel and attenuates by at least 50 dB from 320 kHz to 57 MHz. The input IP3 is +30 dBm, the input-referred noise in the passband is 70 nV/√Hz, and the circuit takes 4.6 mA from a 3.3 V supply. Direct subsampling of the 915 MHz RF input signal by the filter front-end is also demonstrated with only a small degradation in linearity. The input noise voltage is halved in a redesign while keeping the current drain unchanged  相似文献   
3.
Miniaturization and energy consumption by computational systems remain major challenges to address. Optoelectronics based synaptic and light sensing provide an exciting platform for neuromorphic processing and vision applications offering several advantages. It is highly desirable to achieve single-element image sensors that allow reception of information and execution of in-memory computing processes while maintaining memory for much longer durations without the need for frequent electrical or optical rehearsals. In this work, ultra-thin (<3 nm) doped indium oxide (In2O3) layers are engineered to demonstrate a monolithic two-terminal ultraviolet (UV) sensing and processing system with long optical state retention operating at 50 mV. This endows features of several conductance states within the persistent photocurrent window that are harnessed to show learning capabilities and significantly reduce the number of rehearsals. The atomically thin sheets are implemented as a focal plane array (FPA) for UV spectrum based proof-of-concept vision system capable of pattern recognition and memorization required for imaging and detection applications. This integrated light sensing and memory system is deployed to illustrate capabilities for real-time, in-sensor memorization, and recognition tasks. This study provides an important template to engineer miniaturized and low operating voltage neuromorphic platforms across the light spectrum based on application demand.  相似文献   
4.
To achieve size preserving tracking, in addition to controlling the camera’s pan and tilt motions to keep the object of interest in the camera’s field of view (FOV), the camera’s focal length is adjusted automatically to compensate for the changes in the target’s image size caused by the relative motion between the camera and the target. The estimation accuracy of these changes determines the effectiveness of the resulting zoom control. The existing method of choice for real-time target scale estimation applies structure from motion (SFM) based on the weak perspective projection model. In this paper we propose a target scale estimation algorithm with a linear solution based on the more advanced paraperspective projection model, which improves the accuracy of scale estimation by considering center offset. Another key issue in SFM based algorithms is the separation of target and background features, especially when composite camera (pan/tilt/zoom) and target motions are involved. This paper designs a fast target feature separation/grouping algorithm, the 3D affine shape method. The resulting separation automatically adapts to the target’s 3D geometry and motion and is able to accommodate a large amount of off-plane rotation, which most existing separation/grouping algorithms find difficult to achieve. Experimental results illustrate the effectiveness of the proposed scale estimation and feature separation algorithms in tracking translating and rotating objects with a PTZ camera while preserving their sizes. In comparison with the leading size preserving tracking algorithm described by Tordoff and Murray, our algorithm is able to reduce the cumulative tracking error significantly from 17.4% to 3.3%.  相似文献   
5.
Point fingerprint: a new 3-D object representation scheme   总被引:1,自引:0,他引:1  
This paper proposes a new, efficient surface representation method for surface matching. A feature carrier for a surface point, which is a set of two-dimensional (2-D) contours that are the projections of geodesic circles on the tangent plane, is generated. The carrier is named point fingerprint because its pattern is similar to human fingerprints and plays a role in discriminating surface points. Corresponding points on surfaces from different views are found by comparing their fingerprints. The point fingerprint is able to carry curvature, color, and other information which can improve matching accuracy, and the matching process is faster than 2-D image comparison. A novel candidate point selection method based on the fingerprint irregularity is introduced. Point fingerprint is successfully applied to pose estimation of real range data.  相似文献   
6.
p-TsOH-mediated the direct α-substitution of cyclic Morita–Baylis–Hillman alcohols with aliphatic and aromatic thiols in refluxing THF. The reaction proceeded with complete α-regioselectivity and provided the corresponding allyl sulfides in moderate to good yields.  相似文献   
7.
Abstract: A very simple method is proposed to produce hydroxytyrosol, a commercially unavailable compound with well‐known biological properties which justify a potential commercial application. The 2‐phase Chemlali olive pomace is selected as substrate for chemical treatment. Different conditions of chemical treatment, including concentration of acid and alkaline solutions, time and temperature, were assayed. A high amount of hydroxytyrosol (1360 mg/kg of fresh 2‐phase olive pomace) was obtained using water bath after treatment at 80 °C for 90 min with 1 M of H3PO4. However, treatment of 2‐phase Chemlali olive pomace using autoclave apparatus could produce a large amount of hydroxytyrosol (1993.60 and 1515.88 mg/kg of fresh alperujo, 1 M acid and basic catalyst, respectively). By taking into consideration practical and economic aspects, acid‐catalyzed treatment was more effective using autoclave conditions, whereas the alkali catalyzed conditions were not very suitable. This study could provide useful information for industry to produce the potentially bioactive compound. Practical Application: The 2‐phase Chemlali olive pomace is selected as substrate for chemical treatment. Treatment of “alperujo” using water bath or autoclave apparatus was carried out. A high amount of hydroxytyrosol was obtained using autoclave apparatus.  相似文献   
8.
9.
Polar isolates of frying oils used for frying French fries, potato chips, or French fries/tortilla chips were analyzed for nonvolatile components by high-performance size-exclusion chromatography (HPSEC) with viscometric (VIS)/refractometric (RI) detection. The degradation products were separated on three mixed-bed polystyrene/divinylbenzene columns with tetrahydrofuran as eluent. Dual VIS/RI detection of the column effluent enabled simultaneous determination of analyte molecular weights (MW) and concentrations. MW of individual components were calculated from viscosity data with the use of a universal calibration technique. HPSEC of polar samples obtained from different oilseed lines yielded triglyceride-derived products in which the corresponding nonvolatile components had variable MW and compositions. Elevated levels of high-MW components were correlated with the extent of frying oil degradation to serve as indicators for frying oil stability. MW/concentration profiles of degradation products varied notably with frying times. The distribution patterns of degradation products were markedly affected by other frying conditions and oil varieties and therefore served as fingerprint properties of specific oils. High-oleic sunflower oil (HOSUN) (used for frying French fries) appeared to be more stable than cottonseed oil: at 30 h, the concentrations of the highest MW components were 0.63 vs. 0.89 mg/100 mg oil. HOSUN (used for frying French fries/tortilla chips) tended to be more stable than sunflower oil (SUN), as the most abundant (at 30 h, 3.99 vs. 4.34 mg/100 mg oil) species were components 4 (MW=1385) and 3 (MW=2055) for HOSUN and SUN, respectively. High-oleic soybean oil (HOSBO) was notably more stable than soybean oil: at 40 h, the concentrations of the highest MW (2980 vs. 6315) components were 0.21 vs. 4.51 mg/100 mg oil. Presented in part at the 91st AOCS Annual Meeting & Expo, San Diego, California, April 2000.  相似文献   
10.
Ultrasonic setting measurement is the study of how materials set or harden. Indeed, when mixed or combined, some materials undergo a change of their rheological properties if they are submitted to physical or chemical phenomena. Before use, these materials are liquid and they become solid when in use, at temperatures close to ambient levels, for example, hydraulic binding materials (cement, white-wash, plaster). For each particular application, users and manufacturers with to know the evolution such materials undergo, for three reasons:
  • - the development of a new product (meeting a need),
  • - the largest possible reduction of setting time (economic criterion),
  • - the use of the material (moulding, transformation...) without risking a change of its properties (quality-and safety-related problems).
  • The ultrasonic setting-measurement device provides solutions to such needs. The method is based on tracking ultrasounds through an interface during the process of solidification. Recording the change of transmissibility allows monitoring the rheological evolution of the material. Some examples of the use of the ultrasonic setting measurement device are provided, on the basis of laboratory measurements. A comprehensive study of the results of tests using hydraulic binders and acrylic resins allows the determination of characteristic times corresponding to the evolution of the material in question.  相似文献   
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