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81.
Ravindra Kumar Shirsendu Banerjee Anirban Banik Tarun Kanti Bandyopadhyay 《Petroleum Science and Technology》2017,35(6):615-624
The effect of diameter, velocity, and temperature on flow properties of heavy crude oil in three horizontal pipelines using computational fluid dynamics (CFD) was studied. The flow characteristics were simulated by using CFD software, ANSYS Fluent 6.2. The mesh geometry of the pipelines having inner diameter of 1, 1.5, and 2 inch were created by using Gambit 2.4.6. From grid independent study, 221, 365 mesh sizes were selected for simulation. The CFD ANSYS Fluent 6.2 Solver predicted the flow phenomena, pressure, pressure drop, wall shear stress, shear strain rate, and friction factor. A good agreement between experimental and CFD simulated values was obtained. 相似文献
82.
H. D. Chalak Anupam Chakrabarti Abdul Hamid Sheikh Mohd. Ashraf Iqbal 《先进材料力学与结构力学》2015,22(11):897-907
C0 finite element model based on higher order zig-zag plate theory is used to study the stability analysis of laminated sandwich plates. The in-plane displacement field is obtained by superposing a global cubically varying displacement field on a zig-zag linearly varying displacement field with different slope in each layer. The transverse displacement assumes to have a quadratic variation within the core and constant in the faces. The conditions regarding transverse shear stress at layer interfaces and top and bottom are satisfied. Numerical examples covering different features of laminated sandwich plates are presented to illustrate the accuracy of the model. 相似文献
83.
Chi-Li Yu Jung-Sub Kim Lanping Deng Srinidhi Kestur Vijaykrishnan Narayanan Chaitali Chakrabarti 《Journal of Signal Processing Systems》2011,64(1):109-122
Applications based on Discrete Fourier Transforms (DFT) are extensively used in several areas of signal and digital image
processing. Of particular interest is the two-dimensional (2D) DFT which is more computation- and bandwidth-intensive than
the one-dimensional (1D) DFT. Traditionally, a 2D DFT is computed using Row-Column (RC) decomposition, where 1D DFTs are computed
along the rows followed by 1D DFTs along the columns. Both application specific and reconfigurable hardware have utilized
this scheme for high-performance implementations of 2D DFT. However, architectures based on RC decomposition are not efficient
for large input size data due to memory bandwidth constraints. In this paper, we propose an efficient architecture to implement
2D DFT for large-sized input data based on a novel 2D decomposition algorithm. This architecture achieves very high throughput
by exploiting the inherent parallelism due to the algorithm decomposition and by utilizing the row-wise burst access pattern
of the external memory. A high throughput memory interface has been designed to enable maximum utilization of the memory bandwidth.
In addition, an automatic system generator is provided for mapping this architecture onto a reconfigurable platform of Xilinx
Virtex-5 devices. For a 2K ×2K input size, the proposed architecture is 1.96 times faster than RC decomposition based implementation under the same memory
constraints, and also outperforms other existing implementations. 相似文献
84.
Lifeng Miao Jun Jason Zhang Chaitali Chakrabarti Antonia Papandreou-Suppappola 《Journal of Signal Processing Systems》2011,65(2):211-227
Sequential Monte Carlo particle filters (PFs) are useful for estimating nonlinear non-Gaussian dynamic system parameters.
As these algorithms are recursive, their real-time implementation can be computationally complex. In this paper, we analyze
the bottlenecks in existing parallel PF algorithms, and propose a new approach that integrates parallel PFs with independent
Metropolis–Hastings (PPF-IMH) resampling algorithms to improve root mean-squared estimation error (RMSE) performance. We implement
the new PPF-IMH algorithm on a Xilinx Virtex-5 field programmable gate array (FPGA) platform. For a one-dimensional problem
with 1,000 particles, the PPF-IMH architecture with four processing elements uses less than 5% of a Virtex-5 FPGA’s resource
and takes 5.85 μs for one iteration. We also incorporate waveform-agile tracking techniques into the PPF-IMH algorithm. We
demonstrate a significant performance improvement when the waveform is adaptively designed at each time step with 6.84 μs
FPGA processing time per iteration. 相似文献
85.
Improving the Reliability of MLC NAND Flash Memories Through Adaptive Data Refresh and Error Control Coding 总被引:1,自引:0,他引:1
Chengen Yang Hsing-Min Chen Trevor N. Mudge Chaitali Chakrabarti 《Journal of Signal Processing Systems》2014,76(3):225-234
NAND Flash memory has become the most widely used non-volatile memory technology. We focus on multi-level cell (MLC) NAND Flash memories because they have high storage density. Unfortunately MLC NAND Flash memory also has reliability problems due to narrower threshold voltage gap between logical states. Errors in these memories can be classified into data retention (DR) errors and program interference (PI) errors. DR errors are dominant if the data storage time is longer than 1 day and these errors can be reduced by refreshing the data. PI errors are dominant if the data storage time is less than 1 day and these errors can be handled by error control coding (ECC). In this paper we propose a combination of data refresh policies and low cost ECC schemes that are cognizant of application characteristics to address the errors in MLC NAND Flash memories. First, we use Gray code based encoding to reduce the error rates in the four subpages (MSB-even, LSB-even, MSB-odd, LSB-odd) of a 2-bit MLC NAND Flash memory. Next, we apply data refresh techniques where the refresh interval is a function of the program/erase (P/E) frequency of the application. We show that an appropriate choice of refresh interval and BCH based ECC scheme can minimize memory energy while satisfying the reliability constraint. 相似文献
86.
Nano Molecular‐Platform: A Protocol to Write Energy Transmission Program Inside a Molecule for Bio‐Inspired Supramolecular Engineering 下载免费PDF全文
Subrata Ghosh Mrinal Dutta Satyajit Sahu Daisuke Fujita Anirban Bandyopadhyay 《Advanced functional materials》2014,24(10):1364-1371
In a coded self‐assembly, a simple code is written in the molecule, which self‐assembles the molecules into a fractal like structure, which acts as a seed for the next step. As the molecule turns into a complex seed, the code transforms into another form and several seeds self‐assemble into another structure, which acts as a seed for the next step. Until now, this technology was considered as a prerogative of nature. Here, a dendritic network is used to write a basic code by synthetically attaching 32 molecular rotors and doping two controller molecules in its cavity. The code live, which is an energy transmission path in the molecule, is imaged. When the energy transmission path or code is triggered, a series of products generate one after another spontaneously. Two examples are: i) dendritic seed (5–6 nm)→paired nanowire (≈12 nm)→nanowire (≈200 nm)→microwire (500 nm)→wire like rod (1–2 μm)→jelly→rectangular sheet (5 μm). ii) dendritic seed→nano‐sphere (20 nm)→micro‐sphere (500 nm)→large balls(1 μm)→oval shape rod (5–10 μm)→Y, L or T shaped rod assembly. The energy level interactions are tracked using spectroscopy how exactly a directed energy transfer code generates multi‐step synthesis from nano to the visible scale. 相似文献
87.
Anirban Chatterjee Gautam Kumar Mahanti Gourab Ghatak 《International Journal of Satellite Communications and Networking》2014,32(1):25-47
A pattern synthesis method based on Firefly Algorithm (FA) and Artificial Bee Colony (ABC) optimization has been presented to generate satellite footprint patterns from a rectangular planar array of isotropic antennas by modifying the amplitude, phase, and the state of the array elements. Three cases comprising three different footprints of rectangular, square, and circular boundary are generated from the same array by using two different swarm‐based optimization algorithms FA and ABC. Both the algorithms, following the proposed procedures are able to generate the three different footprint patterns while maintaining a satisfactory lower peak side lobe level and ripple. A comparative analysis has been carried out between FA, ABC, and Genetic Algorithm (GA) for the presented problem in terms of fitness value for the three different cases. The superiority of FA and ABC over GA has been established in terms of finding better solutions for all the three cases of the proposed problem. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
88.
Kiran Mariam Wang Cong Papadimitriou George Mandal Anirban Deelman Ewa 《Machine Learning》2020,109(5):1127-1143
Machine Learning - Large-scale scientific workflows rely heavily on high-performance file transfers. These transfers require strict quality parameters such as guaranteed bandwidth, no packet loss... 相似文献
89.
Anirban Chakraborty James C. Earthman 《Metallurgical and Materials Transactions A》1998,29(13):957-964
Creep constrained grain boundary cavitation in a fully lamellar (FL) form of a titanium aluminide intermetallic alloy has
been studied using finite element (FE) techniques. Two different forms of FL models were considered. Cavitation was modeled
in the presence of grain boundary sliding (GBS) for the case of straight former γ grain boundaries. Models of cavitation without
GBS were also performed for a FL microstructure with serrated forme γ grain boundaries. The effect of cavitating facet interaction
on rupture life has been studied. A comparison between the FL forms and a dual-phase equizxed microstructure having the same
phase ratio (α2/γ) was also made to examine the relative susceptibility of these microstructures to high-temperature damage. It has been
observed that the overall effect of interaction between cavitating facets increases the rupture time significantly when these
facets are on adjacent grains. However, in the presence of GBS, cavitation on the facet with narrower separation effectively
reduces the cavity growth rate on the facet with wider separation.
ANIRBAN CHAKRABORTY, formerly Graduate Student Researcher with the Chemical & Biochemical Engineering and Materials Science
(CBEMS) Department, University of California, Irvine.
This article is based on a presentation made in the symposium “Fundamentals of Gamma Titanium Aluminides”, presented at the
TMS Annual Meeting, February 10–12, 1997, Orlando, Florida, under the auspices of the ASM/MSD Flow & Fracture and Phase Transformations
Committees. 相似文献
90.
We reported previously that p.o. administered 5-iodo-2-pyrimidinone-2'-deoxyribose (IPdR) was efficiently converted to 5-iodo-2'-deoxyuridine (IUdR) in athymic mice (T. J. Kinsella et al., Cancer Res., 54: 2695-2700, 1994). Here, we further evaluate IPdR metabolism, systemic toxicity, and percentage DNA incorporation in athymic mouse normal tissues and a human colon cancer xenograft (HT29) using higher p.o. doses of IPdR. These data are compared to results using a continuous infusion of IUdR at the maximum tolerable dose. We also evaluate IPdR metabolism in cytosolic extracts from normal human liver, normal human intestine, and human colorectal cancer specimens. Athymic mice tolerated a daily p.o. bolus of up to 2 g/kg IPdR for 6 days with minimal host toxicity (< or = 10% body weight loss). There was rapid conversion of IPdR to IUdR, with peak plasma levels of IUdR of 40-75 microM at 10 min following a p.o. IPdR bolus of 250-1500 mg/kg. The percentage IUdR-DNA in the HT29 s.c. human tumor xenografts increased 1.5 times (2.3-3.6%) with IPdR doses above 1 g/kg/day for 6 days, whereas the percentage IUdR-DNA incorporation in two proliferating normal tissues (4-4.5% in intestine; 1.6-2.2% in bone marrow) and a quiescent normal tissue (< or = 1% in liver) showed < 1.5-fold increases with the IPdR dose escalation between 1-2 g/kg/day for 6 days. In contrast, using a continuous infusion of IUdR at 100 mg/kg/day, significant systemic toxicity (> 20% body weight loss) was found by day 6 of the infusion. Steady-state plasma IUdR levels were 1.0-1.2 microM during the 6-day infusion, and percentage IUdR-DNA incorporations of 2.3, 8, 6, and 1% were measured in s.c. tumors, normal intestine, normal bone marrow, and normal liver, respectively, following the 6-day infusion. Thus, the p.o. IPdR schedule has an improved therapeutic index, based on percentage IUdR-DNA incorporation in normal and tumor tissues, compared to continuous infusion IUdR at the maximum tolerable dose in athymic mice with this human tumor xenograft. Additionally, a tumor regrowth assay to assess the radiation response of HT29 s.c. xenografts showed a 1.5-fold enhancement (time to regrow to 300% initial tumor volume) with IPdR (1000 mg/kg/day for 6 days) plus fractionated irradiation (XRT; 2 Gy/day for 4 days), compared to XRT (2 Gy/day for 4 days) alone. No enhancement in the radiation response of HT29 s.c. xenografts was found with continuous infusion IUdR (100 mg/kg/day for 6 days) plus XRT (2 Gy/day for 4 days), compared to XRT alone. Using cytosolic extracts from normal human liver specimens, we found a rapid (15-min) conversion of IPdR to IUdR. Coincubation of liver cytosol with IPdR and allopurinol, an inhibitor of xanthine oxidase, had no inhibitory effect on IPdR metabolism, whereas coincubation with IPdR and isovanillin or menadione, analogue substrates for aldehyde oxidase, effectively reduced the amount of IPdR oxidized to IUdR. Significantly less metabolism of IPdR to IUdR was seen in cytosolic extracts from normal human intestine specimens, and no metabolism of IPdR was found in cytosolic extracts from colorectal liver metastases in two patients and from the HT29 human colon cancer xenografts in athymic mice. These additional data indicate that IPdR has the potential for clinical use as a p.o. prodrug for IUdR-mediated radiosensitization of resistant human cancers. 相似文献