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61.
This paper presents an investigation into using a combination of two alternative digital number representations; the residue
number system (RNS) and the signed-digit (SD) number representation in digital arithmetic circuits. The combined number system
is called RNS/SD for short. Since the performance of RNS/SD arithmetic circuits depends on the choice of the moduli set (a
set of pairwise prime numbers), the purpose of this work is to compare RNS/SD number systems based on different sets. Five
specific moduli sets of different lengths are selected. Moduli-set-specific forward and reverse RNS/SD converters are introduced
for each of these sets. A generic conversion technique for moduli sets consisting of any number of elements is also presented.
Finite impulse response (FIR) filters are used as reference designs in order to evaluate the performance of RNS/SD processing.
The designs are evaluated with respect to delay and circuit area in a commercial 0.13 μm CMOS process. For the case of FIR
filters it is shown that generic moduli sets with five or six moduli results in designs with the best area × delay products.
相似文献
Lars Bengtsson (Corresponding author)Email: |
62.
Oil Spill Detection in Radarsat and Envisat SAR Images 总被引:8,自引:0,他引:8
Anne H. S. Solberg Camilla Brekke Per Ove Husoy 《Geoscience and Remote Sensing, IEEE Transactions on》2007,45(3):746-755
We present algorithms for automatic detection of oil spills in synthetic aperture radar (SAR) images. The algorithms consist of three main parts, namely: 1) detection of dark spots; 2) feature extraction from the dark spot candidates; and 3) classification of dark spots as oil spills or look-alikes. The algorithms have been trained on a large number of Radarsat and Envisat Advanced Synthetic Aperture Radar (ASAR) images. The performance of the algorithm is compared to manual and semiautomatic approaches in a benchmark study using 59 Radarsat and Envisat images. The algorithms can be considered to be a good alternative to manual inspection when large ocean areas are to be inspected 相似文献
63.
Christoph Ziegler Stefan Klosz Lars Borchardt Stefan Kaskel Alexander Eychmüller 《Advanced functional materials》2016,26(7):1014-1020
Many different aerogel materials are known to be accessible via the controlled destabilization of the respective nanoparticle suspensions. Especially for applications in heterogeneous catalysis such materials with high specific surface areas are highly desirable. Here, a facile method to obtain a mixed ZnPd/ZnO aerogel via a reductive treatment of a preformed Pd/ZnO aerogel is presented. Different morphologies of the Pd/ZnO aerogels could be achieved by controlling the destabilization of the ZnO sol. All aerogels show a high CO2 selectivity of up to 96% and a very good activity in methanol steam reforming that delivers hydrogen, which is one of the most important fuels for future energy concepts. The method presented is promising for different transition metal/metal oxide systems and hence opens a path to a huge variety of materials. 相似文献
64.
Giuseppe Cantarella Vincenzo Costanza Alberto Ferrero Raoul Hopf Christian Vogt Matija Varga Luisa Petti Niko Münzenrieder Lars Büthe Giovanni Salvatore Alex Claville Luca Bonanomi Alwin Daus Stefan Knobelspies Chiara Daraio Gerhard Tröster 《Advanced functional materials》2018,28(30)
In the field of flexible electronics, emerging applications require biocompatible and unobtrusive devices, which can withstand different modes of mechanical deformation and achieve low complexity in the fabrication process. Here, the fabrication of a mesa‐shaped elastomeric substrate, supporting thin‐film transistors (TFTs) and logic circuits (inverters), is reported. High‐relief structures are designed to minimize the strain experienced by the electronics, which are fabricated directly on the pillars' surface. In this design configuration, devices based on amorphous indium‐gallium‐zinc‐oxide can withstand different modes of deformation. Bending, stretching, and twisting experiments up to 6 mm radius, 20% uniaxial strain, and 180° global twisting, respectively, are performed to show stable electrical performance of the TFTs. Similarly, a fully integrated digital inverter is tested while stretched up to 20% elongation. As a proof of the versatility of mesa‐shaped geometry, a biocompatible and stretchable sensor for temperature mapping is also realized. Using pectin, which is a temperature‐sensitive material present in plant cells, the response of the sensor shows current modulation from 13 to 28 °C and functionality up to 15% strain. These results demonstrate the performance of highly flexible electronics for a broad variety of applications, including smart skin and health monitoring. 相似文献
65.
Oscar Gustafsson Håkan Johansson Lars Wanhammar 《Circuits, Systems, and Signal Processing》2003,22(2):219-238
For recursive filter the maximal sample frequency is bounded by the recursive
loops in the filter. [In this paper, it is understood that recursive filters are infinite-length impulse response (IIR)
filters.] In this work, a filter structure based on the use of the frequency masking
approach is presented that increases the maximal sample frequency for narrowband and
wideband filters by introducing more delay elements in the recursive loops. By using
identical subfilters (except for the periods), the subfilters can be mapped using folding
to a single pipeline/interleaved arithmetic structure yielding an area-efficient implementation.
The filters are potentially suitable for low-power implementation by using power
supply voltage scaling techniques. In this work, the design of the filters is discussed and
estimations of the ripples are derived. Two examples show the viability of the proposed
method. 相似文献
66.
Kinematics of the heart: strain-rate imaging from time-resolved three-dimensional phase contrast MRI
Selskog P Heiberg E Ebbers T Wigström L Karlsson M 《IEEE transactions on medical imaging》2002,21(9):1105-1109
A four-dimensional mapping (three spatial dimensions + time) of myocardial strain-rate would help to describe the mechanical properties of the myocardium, which affect important physiological factors such as the pumping performance of the ventricles. Strain-rate represents the local instantaneous deformation of the myocardium and can be calculated from the spatial gradients of the velocity field. Strain-rate has previously been calculated using one-dimensional (ultrasound) or two-dimensional (2-D) magnetic resonance imaging) techniques. However, this assumes that myocardial motion only occurs in one direction or in one plane, respectively. This paper presents a method for calculation of the time-resolved three-dimensional (3-D) strain-rate tensor using velocity vector information in a 3-D spatial grid during the whole cardiac cycle. The strain-rate tensor provides full information of both magnitude and direction of the instantaneous deformation of the myocardium. A method for visualization of the full 3-D tensor is also suggested. The tensors are visualized using ellipsoids, which display the principal directions of strain-rate and the ratio between strain-rate magnitude in each direction. The presented method reveals the principal strain-rate directions without a priori knowledge of myocardial motion directions. 相似文献
67.
Lars Jorhem 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1999,208(2):106-109
Levels of lead and cadmium were determined in tissues of muscle, liver and kidney from horse, lamb, sheep and reindeer in
Sweden during the years 1994–1997. Mean levels of lead in muscle, liver and kidney from horse were <0.002, 0.13 and 0.047,
from lamb <0.002, 0.031 and 0.053, from sheep <0.002, not analysed and 0.046, and from reindeer 0.003, 0.13 and 0.13 mg/fresh
weight, respectively. The mean levels of cadmium in muscle, liver and kidney from horse were 0.042, 2.5 and 18, from lamb
0.0019, 0.031 and 0.12, from sheep 0.0034, not analysed and 1.0, and from reindeer 0.003, 0.60 and 2.7 mg/fresh weight, respectively.
Comparisons with literature data were attempted. In some cases the results could differ by several orders of magnitude. It
cannot be ruled out that some of the differences between studies might be due to analytical differences, making comparisons
very difficult.
Received: 2 June 1998 相似文献
68.
Apparent chemical composition of nine commercial or semi-commercial whey protein concentrates, isolates and fractions 总被引:2,自引:0,他引:2
Carl Holt Deborah McPhail Ian Nevison Tommy Nylander Jeanette Otte Richard H. Ipsen Rogert Bauer Lars gendal Kees Olieman Kees G. de Kruif Joëlle Léonil Daniel Mollé Gwénaële Henry Jean Louis Maubois M. Dolores Pérez Pilar Puyol Miguel Calvo Stella M. Bury George Kontopidis Iain McNae Lindsay Sawyer Laura Ragona Lucia Zetta Henriette Molinari Bert Klarenbeek Margrethe J. Jonkman Jacques Moulin & Dereck Chatterton 《International Journal of Food Science & Technology》1999,34(5-6):543-556
Summary Analytical results are given for whey powders prepared on a commercial or semi-commercial scale by three companies. Altogether, five preparations enriched in β-lactoglobulin, four whey protein isolates and a fraction enriched in α-lactalbumin were analyzed for protein composition, including %β-lactoglobulin, α-lactalbumin, bovine serum albumin, casein (glyco) macropeptide and the main triglycerides. Protein composition was determined by high pressure gel permeation and reversed phase liquid chromatography and by capillary zone electrophoresis. The extent of modification of the native β-lactoglobulin structure was also measured through the degree of lactosylation and the fraction of accessible free sulphydryl groups. One significant finding was that the calculated recovery of protein following quantitation of the chromatogram or electropherogram was seldom above 90% and occasionally below 60% of that loaded onto the column or capillary, raising doubts as to the reliability of the analytical results. Extrapolation by linear regression to 100% recovery allowed estimates to be made of the true β-lactoglobulin composition of the samples. The nine samples could be placed into three distinct groups with estimated true β-lactoglobulin weight % of 70.9 ± 1.1, 62.0 ± 3.4 and 39.5 ± 4.9. Physico-chemical properties of the group of samples are reported elsewhere (Holt et al ., 1999). 相似文献
69.
Recent years have seen dramatic increases of the use of multimedia applications on the Internet, which typically either lack congestion control or use proprietary congestion control mechanisms. This can easily cause congestion collapse or compatibility problems. Datagram Congestion Control Protocol (Dccp) fills the gap betweenUdp andTcp, featuring congestion control rather than reliability for packet-switched rich content delivery with high degree of flexibility. We present aDccp model designed and implemented withOpnet Modeler, and the experiments and evaluation focused on largely the smoothness of the data rates, and the fairness between concurrentDccp flows andTcp flows. We foundDccp-ccid3 demonstrates stable data rates under different scenarios, and the fairness betweenDccp andTcp is only achieved under certain conditions. We also validated that the throughput ofDccp-Ccid3 is proportional to the average packet size, and relatively fixed packet size is critical for the optimal operation ofDccp. Problems in the slow start phase and insufficient receiver buffer size were identified and we hereby proposed solutions on this. 相似文献
70.
Lars R. Knudsen John Erik Mathiassen Frédéric Muller Søren S. Thomsen 《Journal of Cryptology》2010,23(1):72-90
This paper considers the hash function MD2 which was developed by Ron Rivest in 1989. Despite its age, MD2 has withstood cryptanalytic attacks until recently. This paper contains the state-of-the-art cryptanalytic results on MD2, in particular collision and preimage attacks on the full hash function, the latter having complexity 273, which should be compared to a brute-force attack of complexity 2128. 相似文献