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11.
In this paper, we propose Max Connectivity grooming in WDM mesh networks under static lightpath connection requests. The grooming and wavelength conversion resources are placed at the nodes having maximum connections. We propose a heuristic genetic algorithm (GA) model to solve grooming, routing and wavelength assignment. The GA algorithm has been used to optimize the cost of grooming and wavelength conversion resources. The blocking probability has been investigated under different lightpath connections. The performance of Max Connectivity grooming has been compared with other grooming policies. Our results indicate the improvement of resource utilization with minimum blocking probability. 相似文献
12.
Partha Bhaumik Shuqiang Zhang Pulak Chowdhury Sang-Soo Lee Jong Hyun Lee Biswanath Mukherjee 《Photonic Network Communications》2014,28(1):4-18
This paper gives an overview of software-defined optical networks (SDONs). It explains the general concepts on software-defined networks (SDNs), their relationship with network function virtualization, and also about OpenFlow, which is a pioneer protocol for SDNs. It then explains the benefits and challenges of extending SDNs to multilayer optical networks, including flexible grid and elastic optical networks, and how it compares to generalized multi-protocol label switching for implementing a unified control plane. An overview on the industry and research efforts on SDON standardization and implementation is given next, to bring the reader up to speed with the current state of the art in this field. Finally, the paper outlines the benefits achieved by SDONs for network operators, and also some of the important and relevant research problems that need to be addressed. 相似文献
13.
Jeffrey Beck Richard Scritchfield Billy Sullivan Jamie Teherani Chang-Feng Wan Mike Kinch Martha Ohlson Mark Skokan Lewis Wood Pradip Mitra Mike Goodwin Jim Robinson 《Journal of Electronic Materials》2009,38(8):1579-1592
The operation of the mid-wave infrared (MWIR) HgCdTe cylindrical electron injection avalanche photodiode (e-APD) is described.
The measured gain and excess noise factor are related to the collection region fill factor. A two-dimensional diffusion model
calculates the time-dependent response and steady-state pixel point spread function for cylindrical diodes, and predicts bandwidths
near 1 GHz for small geometries. A 2 μm diameter spot scan system was developed for point spread function and crosstalk measurements at 80 K. An electron diffusion
length of 13.4 μm was extracted from spot scan data. Bandwidth data are shown that indicate bandwidths in excess of 300 MHz for small unit
cells geometries. Dark current data, at high gain levels, indicate an effective gain normalized dark density count as low
as 1000 counts/μs/cm2 at an APD gain of 444. A junction doping profile was determined from capacitance–voltage data. Spectral response data shows
a gain-independent characteristic. 相似文献
14.
Nijwm Wary Pradip Mandal 《AEUE-International Journal of Electronics and Communications》2014,68(10):969-975
In this work we propose a low impedance receiver for on-chip high speed current-mode signalling over global interconnect. The receiver provides a very low input impedance even with a low quiescent power. The low input impedance helps to get high link bandwidth without any passive terminator. Moreover, the receiver has high transimpedance gain over a large bandwidth. This facilitates in reducing the signalling current by 6.7 times compared to a passive termination. A test chip has been fabricated in 0.18 μm CMOS process to test the topology with a prototype global interconnect having a length of 10 mm. Power consumption of the transceiver for a data rate of 2.5 Gbps data is 2 mW. This gives an energy efficiency of 0.8 pJ/b. 相似文献
15.
In this paper, a dynamically reconfigurable, Non-overlap Rotational Time Interleaved (NRTI) switched capacitor (S-C) DC-DC converter is presented. Its S-C module is reconfigurable to generate three different fractions (viz., 1/3, 1/2 and 2/3) of its input supply (Vdd). This maintains good power efficiency while its output voltage gets adjusted over a large range. In addition, a load-current-sensing circuit is integrated within it to dynamically reconfigure the S-C module based on the required driving capability. This feature enables to extend load current range to higher limit and at the same time improves the power efficiency in low load current regime. The S-C module is integrated with a current control loop for load and line regulation.The proposed architecture is simulated in a 0.18 μm CMOS process using dual oxide transistors to demonstrate the efficacy of the proposed topology. The input supply voltage is 3.3 V and the regulated output range is 0.8-1.6 V. Total flying capacitance is 330 pF and the load capacitor value is 50 pF. For an output of 1.35 V, its power efficiency is maintained above 50% over a load current range of 4 -17.6 mA with a peak of 66% at 9 mA. Throughout this current range the output voltage ripple remains within 12 mV. 相似文献
16.
In this work we propose a new current-mode full-duplex (CMFD) signaling scheme for high-speed chip-to-chip data communication. In this scheme, all the internal nodes of the link are maintained at low-impedance, facilitating high-speed data communication. A new hybrid circuit topology required for separating the inbound signal from the outbound signal is presented. The proposed current-mode hybrid is realized by a source-coupled main driver, a scaled down replica stage and a common-gate (CG) transimpedance amplifier (TIA). Detailed design, analysis, noise and jitter characterization of the proposed hybrid is presented. The hybrid is realized in 1.8 V, digital CMOS technology. Using this hybrid circuit topology, CMFD signaling over a chip-to-chip interconnect is demonstrated. The post-layout performance shows 8 Gb/s data transfer rate over a FR4 PCB trace of length 7.5 in. for a target bit-error rate (BER) of 10−12. The FR4 PCB trace is modeled by measured 4-port S-parameters in the frequency range from 100 MHz to 20 GHz. The input-referred noise current of the receiver and output-noise voltage of transmitter are and 5.34 mV, respectively. The standalone power consumption of the hybrid is 14.64 mW. 相似文献
17.
Jatindra N Kalita Pradip Kr Mahanta 《Journal of the science of food and agriculture》1993,62(2):105-109
Black teas manufactured in Darjeeling and Assam were analysed for various macrominerals such as P, K, Ca, Mg and microminerals such as Mn, Fe and Cu. A considerable amount of minerals, eg K (40-46 mg), Mg (2.7-3.0 mg), Ca (0.48-0.66 mg) and traces of Mn (0.28-0.40 mg), Fe (0.16-0.20 mg), P (29-41 μg) and Cu (12-22 μg) were found in a cup of black tea brew. Black teas manufactured from the leaf coming from a pruned section and fine portion usually showed higher mineral content than tea manufactured from unpruned sections and coarse grade teas of Darjeeling. Assam CTC tea was found to be richer in mineral content compared to Darjeeling orthodox tea. 相似文献
18.
We report the first determination of the impact of optical nonlinearities on the information capacity of a fiber optic transmission channel. By modeling interchannel interference in a nonlinear wavelength division multiplexing transmission system as multiplicative Gaussian noise, we show that the information capacity is reduced below the Shannon capacity of the linear communications channel. For systems of practical interest, this imposes a fundamental limitation on the spectral efficiency of optical data transmission. 相似文献
19.
Using channel state dependent packet scheduling to improve TCPthroughput over wireless LANs 总被引:1,自引:0,他引:1
Pravin Bhagwat Partha Bhattacharya Arvind Krishna Satish K. Tripathi 《Wireless Networks》1997,3(1):91-102
In recent years, a variety of mobile computers equipped with wireless communication devices have become popular. These computers
use applications and protocols, originally developed for wired desktop hosts, to communicate over wireless channels. Unlike
wired networks, packets transmitted on wireless channels are often subject to burst errors which cause back to back packet
losses. In this paper we study the effect of burst packet errors and error recovery mechanisms employed in wireless MAC protocols
on the performance of transport protocols such as TCP. Most wireless LAN link layer protocols recover from packet losses by
retransmitting lost segments. When the wireless channel is in a burst error state, most retransmission attempts fail, thereby
causing poor utilization of the wireless channel. Furthermore, in the event of multiple sessions sharing a wireless link,
FIFO packet scheduling can cause the HOL blocking effect, resulting in unfair sharing of the bandwidth. This observation leads
to a new class of packet dispatching methods which explicitly take wireless channel characteristics into consideration in
making packet dispatching decisions. We compare a variety of channel state dependent packet (CSDP) scheduling methods with
a view towards enhancing the performance of transport layer sessions. Our results indicate that by employing a CSDP scheduler
at the wireless LAN device driver level, significant improvement in channel utilization can be achieved in typical wireless
LAN configurations.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
20.
Shen Y Guturu PP Buckles BP 《IEEE transactions on information technology in biomedicine》2012,16(1):98-105
Since wireless capsule endoscopy (WCE) is a novel technology for recording the videos of the digestive tract of a patient, the problem of segmenting the WCE video of the digestive tract into subvideos corresponding to the entrance, stomach, small intestine, and large intestine regions is not well addressed in the literature. A selected few papers addressing this problem follow supervised leaning approaches that presume availability of a large database of correctly labeled training samples. Considering the difficulties in procuring sizable WCE training data sets needed for achieving high classification accuracy, we introduce in this paper an unsupervised learning approach that employs Scale Invariant Feature Transform (SIFT) for extraction of local image features and the probabilistic latent semantic analysis (pLSA) model used in the linguistic content analysis for data clustering. Results of experimentation indicate that this method compares well in classification accuracy with the state-of-the-art supervised classification approaches to WCE video segmentation. 相似文献