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931.
Nataša Maleš-Ilić Aleksandar Atanasković Kurt Blau Matthias Hein 《International Journal of Electronics》2016,103(8):1318-1331
This paper considers the linearisation of an asymmetrical two-way Doherty amplifier by the method that uses the second harmonics and fourth-order non-linear signals for linearisation. These even-order signals for linearisation are extracted at the output of the peaking amplifier, adjusted in amplitude and phase and injected at the input and output of the carrier amplifier transistor in the Doherty configuration. The effect of linearisation has been experimentally confirmed on a fabricated asymmetrical Doherty amplifier with the additional circuit for linearisation. The suppression of the third-order intermodulation products has been carried out for two-tone test, 64QAM and WCDMA digitally modulated signals in a range of signal power. 相似文献
932.
Kapil Juneja Darayus Adil Patel Rajesh Kumar Immadi Balwant Singh Sylvie Naudet Pankaj Agarwal Arnaud Virazel Patrick Girard 《Journal of Electronic Testing》2016,32(6):721-733
Advanced nanometer technologies have led to a drastic increase in operational frequencies resulting in the performance of circuits becoming increasingly vulnerable to timing variations. The increasing process spread in advanced nanometer nodes poses considerable challenges in predicting post-fabrication silicon performance from timing models. Thus, there is a great need to qualify basic building structures on silicon in terms of critical parameters before they could be integrated within a complex System-on-Chip (SoC). The work of this paper presents a configurable circuit and an associated power-aware at-speed test methodology for the purpose of qualifying basic standard cells and complex IP structures to detect the presence of timing faults. Our design has been embedded within test-chips used for the development of the 28 nm Fully Depleted Silicon On Insulator (FD-SOI) technology node. The relevant silicon results and analysis validate the proposed power-aware test methodology for qualification and characterization of IPs and provide deeper insights for process improvements. 相似文献
933.
The intermetallic compounds formed during the reflow and aging of Sn-20In-2.8Ag ball-grid-array (BGA) packages are investigated.
After reflow, a large number of cubic-shaped AuIn2 intermetallics accompanied by Ag2In precipitates appear in the solder matrix, while a Ni(Sn0.72Ni0.28)2 intermetallic layer is formed at the solder/pad interface. With further aging at 100°C, many voids can be observed in the
solder matrix and at the solder/pad interface. The continuous distribution of voids at the interface of specimens after prolonged
aging at 100°C causes their bonding strength to decrease from 5.03 N (as reflowed) to about 3.50 N. Aging at 150°C induces
many column-shaped (Cu0.74Ni0.26)6(Sn0.92In0.08)5 intermetallic compounds to grow rapidly and expand from the solder/pad interface into the solder matrix. The high microhardness
of these intermetallic columns causes the bonding strength of the Sn-20In-2.8Ag BGA solder joints to increase to 5.68 N after
aging at 150°C for 500 h. 相似文献
934.
Waveband switching (WBS) is a promising technique to reduce the switching and transmission costs in the optical domain of a wavelength-division multiplexing (WDM) network. This paper considers the problem of provisioning dynamic traffic using WBS in a WDM mesh network. The network of interest is a homogeneous WBS network, where each node has the functionality of WBS. The problem is called the dynamic WBS problem, which involves searching waveband-routes or wavelength-routes for the dynamically arriving traffic requests. The objective is to minimize the total switching and transmission costs in the optical domain. To solve the dynamic WBS problem, an auxiliary graph model capturing the network state is proposed. Based on the auxiliary graph, two heuristic on-line WBS algorithms with different waveband grouping policies are proposed, namely the wavelength-first WBS algorithm based on the auxiliary graph (WFAUG) and the waveband-first WBS algorithm based on the auxiliary graph (BFAUG). Simulation results indicate that WBS is an attractive technique which reduces the overall switching and transmission costs by up to 30% in the network. The results also show that the WFAUG algorithm outperforms the BFAUG algorithm in terms of port savings and cost savings. 相似文献
935.
There has been a steadily increasing interest in using electrically conductive adhesives as interconnecting materials in electronics
manufacturing. In this paper, several anisotropic conductive adhesive (ACA) pastes were formulated, which consist of diglycidyl
ether of bisphenol F or diglycidyl ether of bisphenol A as polymer matrix, imidazoles as curing agents, and different sizes
of silver (Ag) powders or gold (Au)-coated polymer spheres as conductive particles. The effects of ACA resin and different
curing agents, as well as different conductive particles, on flexible substrate of the flip-chip joint were studied. The results
show that the size and type of different conductive particles have very limited influence on an ACA flip-chip joint. The ACA
resin as well as the curing agent can affect the reliability of the joint. The same results can be applied for the failure
analysis of ACA flip-chip technology. 相似文献
936.
This study investigates the impacts of an electronic marketplace with multiple independent retailers for a smart grocery ordering
system. Apart from replenishing products from suppliers, the system can also purchase/sell products from/to the electronic
marketplace through ‘spot shops’. Both static and dynamic pricing models for the electronic marketplace are developed. An
extensive numerical experiment is conducted and the results show that under both static and dynamic pricing, (i) the inventory
cost of the aggregated supply chain is significantly reduced; (ii) each participant also enjoys significant cost savings from
employing the electronic marketplace. Furthermore, the cost savings increase as the lead times from suppliers increase and/or
the variability of their demands increases. The participants’ cost savings also increase as more participants employ the electronic
marketplace. 相似文献
937.
The electromigration behavior of a Sn-3 wt.%Ag-0.5 wt.%Cu-3 wt.%Bi solder stripe between two Cu electrodes under current stressing
at various densities has been investigated for a current stressing time of 72 h and a temperature of 120°C. After current
stressing at a density of 1.0 × 104 A/cm2, the solder matrix exhibited a slight microstructural change as well as formation of a distributed Cu6Sn5 phase near the anode-side solder/Cu interface. Upon increasing the current density to 3.9 × 104 A/cm2 and 5.0 × 104 A/cm2, a high density of distributed Cu6Sn5 phase was formed across the entire solder stripe, resulting in pronounced microstructural change of the solder. Hillocks
were also formed near the anode-side interface due to accumulation of a Sn-rich phase, a Bi-rich phase, and a distributed
Cu6Sn5 phase, while voids were formed in the solder matrix and at the opposite cathode side. The mechanisms of formation of the
distributed Cu6Sn5 phase and migration of Bi and Sn are discussed. 相似文献
938.
Consider a collection of 802.11 access points. Each serves as the gateway to the Internet for clients in its WiFi cell. These
cells have an arbitrary interference pattern, and reception at a client may be corrupted by transmissions nearby. The popularity
of WiFi has made such dense deployment increasingly common. As interference can seriously degrade performance, there is much
interest in optimizing the configuration of these cells. One factor to consider in optimization is channel share, defined
as the useful fraction of channel bandwidth that an access point gets when there is downlink traffic saturation. Interference
affects channel share on the sender side through carrier sensing and transmission deferral, and on the receiver side through
collisions, which result in exponential backoff and retransmission. There exists a simple, “back-of-the-envelope” (BoE) technique
to model the impact of pairwise sender-side interference. This paper tackles the harder task of determining the impact of
receiver-side and non-pairwise sender-side interference. It proposes a technique for modeling the channel share of wireless
links, and the accuracy is demonstrated with Qualnet simulation. 相似文献
939.
Michael Wu Yang Sun Guohui Wang Joseph R. Cavallaro 《Journal of Signal Processing Systems》2011,65(2):171-183
Turbo code is a computationally intensive channel code that is widely used in current and upcoming wireless standards. General-purpose graphics processor unit (GPGPU) is a programmable commodity processor that achieves high performance computation power by using many simple cores. In this paper, we present a 3GPP LTE compliant Turbo decoder accelerator that takes advantage of the processing power of GPU to offer fast Turbo decoding throughput. Several techniques are used to improve the performance of the decoder. To fully utilize the computational resources on GPU, our decoder can decode multiple codewords simultaneously, divide the workload for a single codeword across multiple cores, and pack multiple codewords to fit the single instruction multiple data (SIMD) instruction width. In addition, we use shared memory judiciously to enable hundreds of concurrent multiple threads while keeping frequently used data local to keep memory access fast. To improve efficiency of the decoder in the high SNR regime, we also present a low complexity early termination scheme based on average extrinsic LLR statistics. Finally, we examine how different workload partitioning choices affect the error correction performance and the decoder throughput. 相似文献
940.
Orthogonal Frequency Division Multiplexing (OFDM) systems are commonly used to mitigate frequency-selective multipath fading
and provide high-speed data transmission. In this paper, we derive new union bounds on the error probability of a coded OFDM
system in wireless environments. In particular, we consider convolutionally coded OFDM systems employing single and multiple
transmit antennas over correlated block fading (CBF) channels with perfect channel state information (CSI). Results show that
the new union bound is tight to simulation results. In addition, the bound accurately captures the effect of the correlation
between sub-carriers channels. It is shown that as the channel becomes more frequency-selective, the performance get better
due to the increased frequency diversity. Moreover, the bound also captures the effect of multi-antenna as space diversity.
The proposed bounds can be applied for coded OFDM systems employing different coding schemes over different channel models. 相似文献