全文获取类型
收费全文 | 1005篇 |
免费 | 19篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 7篇 |
化学工业 | 230篇 |
金属工艺 | 52篇 |
机械仪表 | 31篇 |
建筑科学 | 6篇 |
能源动力 | 32篇 |
轻工业 | 49篇 |
水利工程 | 7篇 |
石油天然气 | 3篇 |
无线电 | 92篇 |
一般工业技术 | 281篇 |
冶金工业 | 82篇 |
原子能技术 | 15篇 |
自动化技术 | 138篇 |
出版年
2023年 | 6篇 |
2022年 | 19篇 |
2021年 | 27篇 |
2020年 | 14篇 |
2019年 | 17篇 |
2018年 | 23篇 |
2017年 | 27篇 |
2016年 | 24篇 |
2015年 | 24篇 |
2014年 | 26篇 |
2013年 | 75篇 |
2012年 | 48篇 |
2011年 | 71篇 |
2010年 | 56篇 |
2009年 | 54篇 |
2008年 | 51篇 |
2007年 | 48篇 |
2006年 | 32篇 |
2005年 | 29篇 |
2004年 | 22篇 |
2003年 | 19篇 |
2002年 | 21篇 |
2001年 | 17篇 |
2000年 | 26篇 |
1999年 | 25篇 |
1998年 | 23篇 |
1997年 | 17篇 |
1996年 | 17篇 |
1995年 | 12篇 |
1994年 | 9篇 |
1993年 | 12篇 |
1992年 | 10篇 |
1991年 | 6篇 |
1990年 | 4篇 |
1989年 | 9篇 |
1988年 | 8篇 |
1987年 | 6篇 |
1986年 | 7篇 |
1985年 | 6篇 |
1984年 | 8篇 |
1983年 | 9篇 |
1982年 | 12篇 |
1981年 | 7篇 |
1980年 | 10篇 |
1979年 | 10篇 |
1978年 | 4篇 |
1977年 | 5篇 |
1975年 | 3篇 |
1974年 | 2篇 |
1971年 | 2篇 |
排序方式: 共有1025条查询结果,搜索用时 439 毫秒
21.
Bahni Ray Dipankar Bandyopadhyay Ashutosh Sharma Sang Woo Joo Shizhi Qian Gautam Biswas 《Microfluidics and nanofluidics》2013,15(1):19-33
Spatiotemporal deformations of the free charged surface of a thin electrolyte film undergoing a coupled electrokinetic flow composed of an electroosmotic flow (EOF) on a charged solid substrate and an electrophoretic flow (EPF) at its free surface are explored through linear stability analysis and the long-wave nonlinear simulations. The nonlinear evolution equation for the deforming surface is derived by considering both the Maxwell’s stresses and the hydrodynamic stresses. The electric potential across the film is obtained from the Poisson–Boltzmann equation under the Debye–Hückel approximation. The simulations show that at the charged electrolyte–air interface, the applied electric field generates an EPF similar to that of a large charged particle. The EOF near the solid–electrolyte interface and the EPF at the electrolyte–air interface are in the same (or opposite) directions when the zeta potentials at the two interfaces are of the opposite (or same) signs. The linear and nonlinear analyses of the evolution equation predict the presence of travelling waves, which is strongly modulated by the applied electric field and the magnitude/sign of the interface zeta potentials. The time and length scales of the unstable modes reduce as the sign of zeta potential at the two interfaces is varied from being opposite to same and also with the increasing applied electric field. The increased destabilization is caused by a reverse EPF near the free surface when the interfaces bear the same sign of zeta potentials. Flow reversal by EPF at the free surface occurs at smaller zeta potential of the free surface when the film is thicker because of less influence of the EOF arising at the solid–electrolyte boundary. The amplitude of the surface waves is found to be smaller when the unstable waves travel at a faster speed. The films can undergo pseudo-dewetting when the free surface is almost stationary under the combined influences of EPF and EOF. The free surface instability of the coupled EOF and EPF has some interesting implications in the development of micro/nano fluidic devices involving a free surface. 相似文献
22.
Choudhury Alokeparna Samanta Sourav Pratihar Sanjoy Bandyopadhyay Oishila 《Applied Intelligence》2022,52(7):7339-7372
Applied Intelligence - Microscopic Image segmentation has a crucial role in detecting and diagnosing numerous critical diseases like Alzheimer’s disease, Kidney disease, Cancer, many... 相似文献
23.
Mayuresh Patole Santanu Bandyopadhyay Dominic C. Y. Foo Raymond R. Tan 《Clean Technologies and Environmental Policy》2017,19(7):1967-1975
Pinch analysis was initially developed as a methodology for optimizing energy efficiency in process plants. Applications of pinch analysis applications are based on common principles of using stream quantity and quality to determine optimal system targets. This initial targeting step identifies the pinch point, which then allows complex problems to be decomposed for the subsequent design of an optimal network using insights drawn from the targeting stage. One important class of pinch analysis problems is energy planning with footprint constraints, which began with the development of carbon emissions pinch analysis; in such problems, energy sources and demands are characterized by carbon footprint as the quality index. This methodology has been extended by using alternative quality indexes that measure different sustainability dimensions, such as water footprint, land footprint, emergy transformity, inoperability risk, energy return on investment and human fatalities. Pinch analysis variants still have the limitation of being able to use one quality index at a time, while previous attempts to develop pinch analysis methods using multiple indices have only been partially successful for special cases. In this work, a multiple-index pinch analysis method is developed by using an aggregate quality index, based on a weighted linear function of different quality indexes normally used in energy planning. The weights used to compute the aggregate index are determined via the analytic hierarchy process. A case study for Indian power sector is solved to illustrate how this approach allows multiple sustainability dimensions to be accounted for in energy planning. 相似文献
24.
J. B. Mandal B. Bandyopadhyay B. Ghosh H. Rajagopal A. Sequeira J. V. Yakhmi 《Journal of Superconductivity》1996,9(2):253-257
Rietveld analysis of powder neutron diffraction pattern recorded on Sr-based 1201-phase superconductor (T
c
=53 K), (Hg0.7Cr0.3)Sr2CuO4+ shows that the oxygen atoms at O(3) site are disordered atx=y=0.3712. This fourfold split site has a total combined occupancy of 80% and is the only occupied site in the (Hg, Cr)O plane. 相似文献
25.
The microstructural development during annealing of a cold-deformed 6061Al metal matrix composite (MMC) reinforced with either 3 or 20 m diameter SiC particles has been investigated. The composites were compressed to low (< 10%) levels of strain and then annealed at either 350 or 450°C for different times. Microstructure examination was carried out by transmission electron microscopy and optical microscopy. The results reveal that prior grain boundaries and constituent particles are the dominant sites for recrystallization in both composites, although some nucleation was observed adjacent to the larger SiC particles. The concurrent presence of Mg2Si precipitates affected the progress of recrystallization. 相似文献
26.
Sriparna Saha Author Vitae Sanghamitra Bandyopadhyay Author Vitae 《Pattern recognition》2010,43(3):738-751
In this paper the problem of automatic clustering a data set is posed as solving a multiobjective optimization (MOO) problem, optimizing a set of cluster validity indices simultaneously. The proposed multiobjective clustering technique utilizes a recently developed simulated annealing based multiobjective optimization method as the underlying optimization strategy. Here variable number of cluster centers is encoded in the string. The number of clusters present in different strings varies over a range. The points are assigned to different clusters based on the newly developed point symmetry based distance rather than the existing Euclidean distance. Two cluster validity indices, one based on the Euclidean distance, XB-index, and another recently developed point symmetry distance based cluster validity index, Sym-index, are optimized simultaneously in order to determine the appropriate number of clusters present in a data set. Thus the proposed clustering technique is able to detect both the proper number of clusters and the appropriate partitioning from data sets either having hyperspherical clusters or having point symmetric clusters. A new semi-supervised method is also proposed in the present paper to select a single solution from the final Pareto optimal front of the proposed multiobjective clustering technique. The efficacy of the proposed algorithm is shown for seven artificial data sets and six real-life data sets of varying complexities. Results are also compared with those obtained by another multiobjective clustering technique, MOCK, two single objective genetic algorithm based automatic clustering techniques, VGAPS clustering and GCUK clustering. 相似文献
27.
Automatic MR brain image segmentation using a multiseed based multiobjective clustering approach 总被引:2,自引:2,他引:0
In this paper, the automatic segmentation of a multispectral magnetic resonance image of the brain is posed as a clustering
problem in the intensity space. The automatic clustering problem is thereafter modelled as solving a multiobjective optimization
(MOO) problem, optimizing a set of cluster validity indices simultaneously. A multiobjective clustering technique, named MCMOClust, is used to solve this problem. MCMOClust utilizes a recently developed simulated annealing based multiobjective optimization method as the underlying optimization
strategy. Each cluster is divided into several small hyperspherical subclusters and the centers of all these small sub-clusters
are encoded in a string to represent the whole clustering. For assigning points to different clusters, these local sub-clusters
are considered individually. For the purpose of objective function evaluation, these sub-clusters are merged appropriately
to form a variable number of global clusters. Two cluster validity indices, one based on the Euclidean distance, XB-index,
and another recently developed point symmetry distance based cluster validity index, Sym-index, are optimized simultaneously to automatically evolve the appropriate number of clusters present in MR brain images.
A semi-supervised method is used to select a single solution from the final Pareto optimal front of MCMOClust. The present method is applied on several simulated T1-weighted, T2-weighted and proton density normal and MS lesion magnetic
resonance brain images. Superiority of the present method over Fuzzy C-means, Expectation Maximization clustering algorithms
and a newly developed symmetry based fuzzy genetic clustering technique (Fuzzy-VGAPS), are demonstrated quantitatively. The
automatic segmentation obtained by multiseed based multiobjective clustering technique (MCMOClust) is also compared with the available ground truth information. 相似文献
28.
Chakrabarti A Naik V Dechoudhury S Bandyopadhyay A Mondal M Pandey HK Roy TK Sanyal D Bhowmick D 《The Review of scientific instruments》2007,78(4):043303
A 33.7 MHz heavy-ion radio frequency quadrupole (RFQ) linear accelerator has been designed, built, and tested. It is a four-rod-type RFQ designed for acceleration of 1.38 keVu, qA> or =116 ions to about 29 keVu. Transmission efficiencies of about 85% and 80% have been measured for the unanalyzed and analyzed beams, respectively, of oxygen ((16)O(2+), (16)O(3+), (16)O(4+)), nitrogen ((14)N(3+), (14)N(4+)), and argon ((40)Ar(4+)). The system design and measurements along with results of beam acceleration test will be presented. 相似文献
29.
A stability-based distributed routing mechanism to support unicast and multicast routing in ad hoc wireless network 总被引:6,自引:0,他引:6
An ad hoc network can be envisioned as a collection of mobile routers, each equipped with a wireless transceiver, which are free to move about arbitrarily. In ad hoc wireless networks, even if two nodes are outside the wireless transmission range of each other, they may still be able to communicate in multiple hops using other intermediate nodes. However, the dynamics of these networks, as a consequence of mobility and disconnection of mobile hosts, pose a number of problems in designing routing schemes for effective communication between any pair of source and destination. In this paper, a stability-based unicast routing mechanism, that considers both link affinity and path stability in order to find out a stable route from source to destination, is proposed. It is then extended to support multicast routing as well where only local state information (at source) is utilized for constructing a multicast tree. The performance of the proposed scheme is evaluated on a simulated environment to show that the stability-based scheme provides a unified framework for both unicast and multicast routing and reduces the probability of route error drastically in both the cases. 相似文献
30.
SAFE: An Efficient Feature Extraction Technique 总被引:1,自引:0,他引:1
Ujjwal Maulik Sanghamitra Bandyopadhyay John C. Trinder 《Knowledge and Information Systems》2001,3(3):374-387
This paper proposes an efficient window-based semi-automatic feature extraction technique which uses simulated annealing
for minimizing the energy of an active contour within a specified image region. The energy is computed based on a chamfer
image, in which pixel values are a function of distance to image edges. A user places a number of control points close to
the feature of interest. B-spline fitted to these points provides an initial approximation of the contour. A window containing
both the initial contour and the feature of interest is considered. The contour with minimum energy inside the window provides
the final delineation. Comparison of the performance of the proposed algorithm with traditional snake, a popular feature extraction technique based on energy minimization, demonstrates the superiority of the SAFE technique.
Received 18 August 1999 / Revised 25 October 2000 / Accepted in revised form 8 December 2000 相似文献