全文获取类型
收费全文 | 2422篇 |
免费 | 81篇 |
国内免费 | 6篇 |
专业分类
电工技术 | 48篇 |
综合类 | 5篇 |
化学工业 | 490篇 |
金属工艺 | 57篇 |
机械仪表 | 76篇 |
建筑科学 | 35篇 |
矿业工程 | 13篇 |
能源动力 | 119篇 |
轻工业 | 159篇 |
水利工程 | 5篇 |
石油天然气 | 3篇 |
无线电 | 356篇 |
一般工业技术 | 544篇 |
冶金工业 | 260篇 |
原子能技术 | 15篇 |
自动化技术 | 324篇 |
出版年
2023年 | 29篇 |
2022年 | 51篇 |
2021年 | 58篇 |
2020年 | 54篇 |
2019年 | 42篇 |
2018年 | 89篇 |
2017年 | 64篇 |
2016年 | 87篇 |
2015年 | 61篇 |
2014年 | 88篇 |
2013年 | 166篇 |
2012年 | 107篇 |
2011年 | 146篇 |
2010年 | 82篇 |
2009年 | 114篇 |
2008年 | 71篇 |
2007年 | 88篇 |
2006年 | 60篇 |
2005年 | 59篇 |
2004年 | 43篇 |
2003年 | 60篇 |
2002年 | 40篇 |
2001年 | 60篇 |
2000年 | 63篇 |
1999年 | 44篇 |
1998年 | 71篇 |
1997年 | 81篇 |
1996年 | 58篇 |
1995年 | 41篇 |
1994年 | 45篇 |
1993年 | 42篇 |
1992年 | 48篇 |
1991年 | 50篇 |
1990年 | 18篇 |
1989年 | 25篇 |
1988年 | 29篇 |
1987年 | 20篇 |
1986年 | 16篇 |
1985年 | 23篇 |
1984年 | 19篇 |
1983年 | 17篇 |
1982年 | 10篇 |
1981年 | 11篇 |
1980年 | 12篇 |
1979年 | 9篇 |
1978年 | 6篇 |
1977年 | 4篇 |
1976年 | 8篇 |
1975年 | 4篇 |
1969年 | 3篇 |
排序方式: 共有2509条查询结果,搜索用时 15 毫秒
1.
Bhattacharya Subhayan Sinha Sankhamita Roy Sarbani Gupta Amarnath 《The Journal of supercomputing》2020,76(12):9882-9900
The Journal of Supercomputing - Currently, all online social networks (OSNs) are considered to follow a power-law distribution. In this paper, the degree distribution for multiple OSNs has been... 相似文献
2.
3.
Windlass H. Raj P.M. Balaraman D. Bhattacharya S.K. Tummala R.R. 《Electronics Packaging Manufacturing, IEEE Transactions on》2003,26(2):100-105
Polymer ceramic composites form a suitable material system for low temperature fabrication of embedded capacitors appropriate for the MCM-L technology. Improved electrical properties such as permittivity can be achieved by efficient filling of polymers with high dielectric constant ceramic powders such as lead magnesium niobate-lead titanate (PMN-PT) and barium titanate (BT). Photodefinable epoxies as the matrix polymer allow fine feature definition of the capacitor elements by conventional lithography techniques. The optimum weight percent of dispersant is tuned by monitoring the viscosity of the suspension. The dispersion mechanism (steric and electrostatic contribution) in a slightly polar solvent such as propylene glycol methyl ether acetate (PGMEA) is investigated from electrophoretic measurements. A high positive zeta potential is observed in the suspension, which suggests a strong contribution of electrostatic stabilization. By optimizing the particle packing using a bimodal distribution and modified processing methodology, a dielectric constant greater than 135 was achieved in PMN-PT/epoxy system. Suspensions are made with the lowest PGMEA content to ensure the efficiency of the dispersion and efficient particle packing in the dried film. Improved colloidal processing of nanoparticle-filled epoxy is a promising method to obtain ultra-thin capacitor films (<2/spl mu/m) with high capacitance density and improved yield. Capacitance of 35 nF/cm/sup 2/ was achieved with the thinnest films (2.5-3.0 /spl mu/m). 相似文献
4.
Oleg A. Mezentsev Rixin Zhu Richard E. DeVor Shiv G. Kapoor William A. Kline 《International Journal of Machine Tools and Manufacture》2002,42(4)
A model-based method for fault detection in tapping based on torque and radial forces is proposed. The method allows the identification of faults typical of a tapping operation including axial misalignment, tap runout, tooth breakage both singly and together. The validation experiments have been run on aluminum 356 workpieces for different combinations of process faults. Results have shown that the model predictions are in good agreement with the experimental radial force and torque signals under various fault conditions. 相似文献
5.
Seo K. Heiblum M. Knoedler C.M. Oh J.E. Pamulapati J. Bhattacharya P. 《Electron Device Letters, IEEE》1989,10(2):73-75
A high-gain ballistic hot-electron device is described. The GaAs-AlGaAs heterostructure device, with a 21-mm-thick pseudomorphic In 0.12Ga0.88As base, had a current gain of 27 at 77 K and 41 at 4.2 K. As characteristically seen in ballistic devices, transfer into the L valley limited the maximum gain. The Γ-L valley separation in the strained In0.12Ga0.88As was estimated to be about 380 meV 相似文献
6.
Yuan Y. Jambunathan R. Singh J. Bhattacharya P. 《Quantum Electronics, IEEE Journal of》1997,33(3):408-415
The performance characteristics of a coupled cavity InGaAsP-InP MQW laser/active waveguide made by one-step epitaxy and well-controlled reactive ion etching (RIE) have been theoretically analyzed and experimentally determined. A theoretical model based on a finite-difference time-domain (FDTD) technique was used to simulate the propagation of an optical wave launched in the coupled system and determine the reflectivity of the facets created by RIE. The calculated effective reflectivity of the coupling region consisting of two facets and an air gap is between 0.45 and 0.55, which is in good agreement with the experimentally measured value of 0.5. The reflectivity of a single etched mirror derived from this value is estimated to be 0.3. A 120-μm-long monolithically integrated active waveguide when biased as a modulator and excited by the laser shows a maximum extinction ratio of 8 dB and a modulation bandwidth ⩾14 GHz at a dc bias of -0.5 V with a bias swing of 2 V 相似文献
7.
J Tyson L Tranebjaerg S Bellman C Wren JF Taylor J Bathen B Aslaksen SJ S?rland O Lund S Malcolm M Pembrey S Bhattacharya M Bitner-Glindzicz 《Canadian Metallurgical Quarterly》1997,6(12):2179-2185
The Jervell and Lange-Nielsen syndrome (JLNS) comprises profound congenital sensorineural deafness associated with syncopal episodes. These are caused by ventricular arrhythmias secondary to abnormal repolarisation, manifested by a prolonged QT interval on the electrocardiogram. Recently, in families with JLNS, Neyroud et al. reported homozygosity for a single mutation in KVLQT1 , a gene which has previously been shown to be mutated in families with dominantly inherited isolated long QT syndrome [Neyroud et al . (1997) Nature Genet ., 15, 186-189]. We have analysed a group of families with JLNS and shown that the majority are consistent with mutation at this locus: five families of differing ethnic backgrounds were homozygous by descent for markers close to the KVLQT1 gene and a further three families from the same geographical region were shown to be homozygous for a common haplotype and to have the same homozygous mutation of the KVLQT1 gene. However, analysis of a single small consanguineous family excluded linkage to the KVLQT1 gene, establishing genetic heterogeneity in JLNS. The affected children in this family were homozygous by descent for markers on chromosome 21, in a region containing the gene IsK . This codes for a transmembrane protein known to associate with KVLQT1 to form the slow component of the delayed rectifier potassium channel. Sequencing of the affected boys showed a homozygous mutation, demonstrating that mutation in the IsK gene may be a rare cause of JLNS and that an indistinguishable phenotype can arise from mutations in either of the two interacting molecules. 相似文献
8.
In this paper, we propose a new definition of digital connectivity for gray images on a 2D space for arbitrary grid systems. We extend a digital version of the Jordan curve theorem and its converse proved earlier by Rosenfeld for the rectangular grid system. We also extend in two directions the concept of well-composed sets introduced by Lateckiet al.(1995,Comput. Vision Image Understanding61,70–83). First, we extend the definition of well-composed sets from the quadratic grid system to an arbitrary grid system. Then, by using the concept of parameter-dependent connected components introduced by us in a previous work, we allow the pixels in a connected component of a well-composed set to have different gray values so that the connectivity of connected components accommodates a wider meaning. 相似文献
9.
A. Bhattacharya 《International Journal of Fracture》1996,78(2):131-138
A complex analysis of rigid body rotation is presented. The crack-tip rotation for a line crack subjected to steady uniform heat flow is obtained in terms of thermal stress intensity factor in shear mode of the crack, the material and thermal parameters and coordinates of points close to the crack tip. The shear strip configuration is analysed on the basis of rotation and displacement at the end of the shear strip. 相似文献
10.
In recent years, an increasing need has arisen for various types of construction on sites underlain by soft cohesive soils. In such cases, some methods of soil improvement are usually required to provide adequate bearing capacity and tolerable postconstruction total and differential settlements. These goals often may be achieved by precompression or preloading the site prior to construction. Precompression and preloading are frequently used in combination with vertical drains, especially in very thick soft deposits, otherwise the time required for consolidation may be unacceptably long or the instability of the foundation may be a serious concern. Therefore, the vertical geocomposite (jute and coir) drain may be used to accelerate the settlement of soil thereby making the site available for use in the shortest time. The computer program and the design chart for determining the spacing between geocomposite drains are presented. This technique is generally useful for embankment construction, tank foundation, underwater construction and landfill areas. Two projects (Haldia in West Bengal and Vashi Station Complex in Bombay) have utilized the application of geocomposite drains reported in this paper. 相似文献