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31.
van Waasen S. Umbach A. Auer U. Bach H.-G. Bertenburg R.M. Janssen G. Mekonnen G.G. Passenberg W. Reuter R. Schlaak W. Schramm C. Unterborsch G. Wolfram P. Tegude F.-J. 《Solid-State Circuits, IEEE Journal of》1997,32(9):1394-1401
A monolithic integrated photoreceiver for 1.55-μm wavelength has been designed for operation in a 20-Gb/s synchronous digital hierarchy system (SDH/SONET), based on a new integration concept. The optoelectronic integrated circuit (OEIC) receiver combines a waveguide-integrated PIN-photodiode and a traveling wave amplifier in coplanar waveguide layout with four InAlAs/InGaAs/InP-HFETs (0.7-μm gate length). The receiver demonstrates a bandwidth of 27 GHz with a low frequency transimpedance of 40 dBΩ. This is, to our knowledge, the highest bandwidth ever reported for a monolithic integrated photoreceiver on InP. Furthermore, a receiver sensitivity of -12 dBm in the fiber (20 Gb/s, BER=10-9) and an overall optical input dynamic range of 27 dB is achieved. Optical time domain multiplex (TDM) system experiments of the receiver packaged in a module show an excellently shaped eye pattern for 20 Gb/s and an overall sensitivity of -30.5 dBm (BER=10-9) [including erbium doped fiber amplifiers (EDFA)] 相似文献
32.
Several cognitive impairment/dementia diagnostic methods were examined concerning their results: (a) in the differentiation of accidental and pathological ability changes; (b) in the demonstration/exclusion of cognitive impairment; and (c) the degree of dementia. Sixty-five patients suffering from brain damage were examined with five accepted methods of diagnosing dementia (Syndrom-kurztest, KAI-MWT-Methode, Demenz-Test, Mini-Mental-Status-Test, Wurzer-Methode) and a comprehensive performance test battery as an external criterion for valid determination of the degree of dementia and definite differentiation of accidental and pathological performance changes. The five methods of diagnosing dementia differ appreciably in determining the degree of severity (r = 0.44). They are effective in registering accidental performance changes in comparison with the outer criterion, but pathological changes are inaccurately registered (hit rate 88%/53%); the results concerning the degree of cognitive impairment are identical: between 25 and 43% (r = 0.43). High rates (58%) of false-negative diagnoses are especially apparent in the range of slight and intermediate cognitive impairment. The methods examined are only useful for the demonstration and not for the exclusion of severe cognitive impairment (dementia) and in no circumstances for the registration of slight/intermediate cognitive impairment. Valid diagnosis of cognitive impairment/dementia necessitates the use of test batteries that differentiate functions including the premorbid performance level. 相似文献
33.
The random variability of fetal heart rate (FHR) is of practical importance in obstetric management. The variability is not white, however, and cannot be adequately described by its variance alone. We have modeled FHR variability as the scalar output of a multivariate, nonlinear stochastic process. An adaptation of the Kalman filter algorithm is used as part of an approximate maximum likelihood estimator of the process parameters. The filter algorithm permits recording artifacts to be disregarded, by treating them as "missing" observations. 相似文献
34.
Ceramic samples in the system ZrO2TiO2SnO2 were prepared in order to investigate the existence range of a homogeneous phase ZrxTiySnzO4 with x+y+z=2. Lattice parameters, dielectric properties and thermal expansion were determined. A homogeneous solid solution phase was found in part of the composition diagram. Its crystal structure is isomorphous with ZrTiO4. The unusual variation of the lattice parameters with the Sn content is discussed and the range of compositions suitable for dielectric resonators is defined. 相似文献
35.
Generation of geometrically and radiometrically terrain corrected SAR image products 总被引:2,自引:0,他引:2
Terrain undulations affect the geometric and radiometric quality of synthetic aperture radar images. The correction of these effects becomes indispensable when quantitative image analysis is performed with respect to the derivation of geo- and biophysical parameters. The paper presents a rigorous approach for geometric and radiometric correction of SAR images. Using a digital elevation model, the imaging geometry is reconstructed and is used to perform geometric and radiometric correction of terrain induced distortions. The importance of a stringent radiometric correction based on the integration of the image brightness is emphasized. The approach guarantees that the energy contained in the image data is preserved throughout the geocoding process. The resulting backscattering images are fully terrain corrected and can be used for further quantitative investigations and may also improve qualitative studies as e.g. land cover classifications. The technique is applicable for different sensor types and image products, including already geocoded SAR images. The effect of different resolutions of digital elevation models used for the correction of the backscattering coefficient is investigated. 相似文献
36.
Armin Hornung Kai M. Wurm Maren Bennewitz Cyrill Stachniss Wolfram Burgard 《Autonomous Robots》2013,34(3):189-206
Three-dimensional models provide a volumetric representation of space which is important for a variety of robotic applications including flying robots and robots that are equipped with manipulators. In this paper, we present an open-source framework to generate volumetric 3D environment models. Our mapping approach is based on octrees and uses probabilistic occupancy estimation. It explicitly represents not only occupied space, but also free and unknown areas. Furthermore, we propose an octree map compression method that keeps the 3D models compact. Our framework is available as an open-source C++ library and has already been successfully applied in several robotics projects. We present a series of experimental results carried out with real robots and on publicly available real-world datasets. The results demonstrate that our approach is able to update the representation efficiently and models the data consistently while keeping the memory requirement at a minimum. 相似文献
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38.
Runoff-farming, a water harvesting technique, is the diversion of rain water from a collecting area to a cropping area, thereby increasing the quantity of water available for crop growth. This technique, applicable in various types, is regarded as necessary to secure and increase food production in semi-arid regions. Simultaneously it minimizes water erosion risk where it is applied. As the potential of runoff-farming has not been investigated, a methodology had to be developed to enable planners to identify suitable areas the most efficient way. Five main information sources are tapped: ground checks by various specialists, maps, data, aerial photographs and satellite images. The interpretation of the collected data yields in the quantification of the runoff water, the water requirements of the crops and the water storage capacity of the soil. All factors have to be validated and integrated into a decision model. 相似文献
39.
40.
Prof. Dr.‐Ing. Wolfram Jäger 《Mauerwerk》2013,17(3):189-190