全文获取类型
收费全文 | 249篇 |
免费 | 14篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 2篇 |
化学工业 | 78篇 |
金属工艺 | 3篇 |
机械仪表 | 2篇 |
建筑科学 | 4篇 |
矿业工程 | 1篇 |
能源动力 | 8篇 |
轻工业 | 8篇 |
水利工程 | 3篇 |
石油天然气 | 5篇 |
无线电 | 48篇 |
一般工业技术 | 46篇 |
冶金工业 | 23篇 |
原子能技术 | 1篇 |
自动化技术 | 35篇 |
出版年
2024年 | 4篇 |
2023年 | 4篇 |
2022年 | 8篇 |
2021年 | 12篇 |
2020年 | 7篇 |
2019年 | 11篇 |
2018年 | 18篇 |
2017年 | 10篇 |
2016年 | 12篇 |
2015年 | 7篇 |
2014年 | 23篇 |
2013年 | 22篇 |
2012年 | 11篇 |
2011年 | 16篇 |
2010年 | 16篇 |
2009年 | 13篇 |
2008年 | 8篇 |
2007年 | 9篇 |
2006年 | 6篇 |
2005年 | 3篇 |
2004年 | 4篇 |
2003年 | 3篇 |
2002年 | 7篇 |
2001年 | 3篇 |
2000年 | 2篇 |
1999年 | 3篇 |
1998年 | 3篇 |
1997年 | 2篇 |
1996年 | 2篇 |
1995年 | 2篇 |
1994年 | 3篇 |
1993年 | 3篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1976年 | 2篇 |
排序方式: 共有267条查询结果,搜索用时 9 毫秒
61.
62.
In this paper, we propose a speech enhancement method where the front-end decomposition of the input speech is performed by temporally processing using a filterbank. The proposed method incorporates a perceptually motivated stationary wavelet packet filterbank (PM-SWPFB) and an improved spectral over-subtraction (I-SOS) algorithm for the enhancement of speech in various noise environments. The stationary wavelet packet transform (SWPT) is a shift invariant transform. The PM-SWPFB is obtained by selecting the stationary wavelet packet tree in such a manner that it matches closely the non-linear resolution of the critical band structure of the psychoacoustic model. After the decomposition of the input speech, the I-SOS algorithm is applied in each subband, separately for the estimation of speech. The I-SOS uses a continuous noise estimation approach and estimate noise power from each subband without the need of explicit speech silence detection. The subband noise power is estimated and updated by adaptively smoothing the noisy signal power. The smoothing parameter in each subband is controlled by a function of the estimated signal-to-noise ratio (SNR). The performance of the proposed speech enhancement method is tested on speech signals degraded by various real-world noises. Using objective speech quality measures (SNR, segmental SNR (SegSNR), perceptual evaluation of speech quality (PESQ) score), and spectrograms with informal listening tests, we show that the proposed speech enhancement method outperforms than the spectral subtractive-type algorithms and improves quality and intelligibility of the enhanced speech. 相似文献
63.
64.
Yogesh Chandrakant Rotliwala Parimal Amaratlal Parikh 《Korean Journal of Chemical Engineering》2011,28(3):788-792
Thermal degradation behavior of mixtures of rice bran (RB) and high density polyethylene (HDPE) was investigated by thermo-gravimetric analyses (TGA) under dynamic conditions in nitrogen atmosphere and was compared with that of individual materials. Experiments were carried out in the range of ambient temperature to 900 °C at two heating rates (5 and 20 °C per minute). Kinetic analysis indicated that activation energy for pyrolysis of RB, HDPE and those for RB-HDPE mixtures varied with rate of heating as well as with the three temperature ranges. This variation has been explained on the materials’ decomposition behavior. Maximum difference between experimental and theoretical mass loss (Δm) was 26% at 475 °C and 34% at 489 °C at the heating rates of 5 and 20 °C per minute, respectively. These maxima indicate stronger interactions at corresponding temperature between RB and HDPE during copyrolysis. Reduction in activation energy for pyrolysis, lower temperatures at which rate of decomposition is highest, and negligible quantity of the residue suggest a synergism between thermal degradation of RB and HDPE. 相似文献
65.
Basudeb Karmakar Paritosh Kundu Ravindra Nath Dwivedi 《Journal of the American Ceramic Society》2000,83(5):1305-1307
Fluorophosphate glasses of the Ba(PO3 )2 –MgF2 –CaF2 –AlF3 system exhibit anomalous behavior, in regard to the glass-transition temperature ( T g ) and the coefficient of thermal expansion (αCTE ), at a fluoride concentration of ∼36 mol%. A similar trend in the infrared band absorption coefficient (αIR ) at 2170 cm−1 of the overtone of 2νss (OPO) and/or a combination of νas (OPO)+νas (POP) fundamental vibrations of PO4 tetrahedra also has been observed, relative to changes in the glass composition. Statistical analyses have shown that the T g and αCTE values are correlated with αIR at 2170 cm−1 by linear equations. The thermal properties of some of the glasses have been calculated using these equations, to test their validity and utility. The experimental property values of the glasses present a very good fit of data within a 95% confidence interval of the calculated mean values. 相似文献
66.
Atmospheric water vapour was measured over a tropical location, Calcutta, by deploying dual frequency microwave radiometers operating at 22.235 and 31.4 GHz. Simultaneous measurements of brightness temperature and hence attenuation in the presence of thin cloud were made for the purpose. An algorithm was developed to exclude the effect of non-precipitating liquid water during the measurement of water vapour. The experimental results are supported by the corresponding radiosonde data analysis. Dual frequency radiometric measurements are shown to improve the rms accuracy, over the single frequency inversion technique, for the measurement of water vapour. 相似文献
67.
68.
Mahua Upadhyay Gobinda Karmakar Gurpreet Singh Kapur Pranab Ghosh 《Polymer Engineering and Science》2018,58(5):810-815
In an anticipation to produce biodegradable additives with multifunctional performance for a cost‐effective lubricant composition, copolymers are synthesized by incorporating rice bran oil, peanut oil, β‐pinene in the backbone of isodecyl acrylate through microwave irradiation method using AIBN (azobisisobutyronitrile) as radical initiator. The prepared polymers are characterized by spectral techniques (IR, NMR) and SEC‐GPC analysis, thermal stability was determined by thermogravimetric analysis. Performance of the polymers as antiwear (AW), pour point depressant (PPD), viscosity modifier/viscosity index improver (VII) in different mineral base oils (SN1 and SN2) were done by standard ASTM methods. Biodegradability test of the polymers was carried out by disk diffusion (DD) and soil burial test methods. The copolymers of rice bran oil showed better viscosity index values and AW property, whereas the copolymers of peanut oil found to be most effective as PPD. Copolymers with higher concentration of green units showed better performance as viscosity modifier, pour point depressant and AW performance along with excellent biodegradability. POLYM. ENG. SCI., 2017. © 2017 Society of Plastics Engineers 相似文献
69.
Sodium alginate-g-polyacrylamide (SAG) was synthesized by ceric ion induced redox polymerization technique. Six grades of graft copolymers were prepared by varying as well as monomer concentrations. The graft copolymers were characterized by intrinsic viscosity measurements, IR, and 13C-NMR spectroscopies. Of the above grades, the graft copolymer of grade six (SAG-VI), which has longer polyacrylamide chains, was used for flocculation study. Two coking and noncoking coal fine suspensions were selected for the flocculation study. The flocculation performance of the graft copolymer was compared with commercial flocculants. In all cases, it was found that the graft copolymer showed better performance than the commercial flocculants. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 375–382, 2001 相似文献
70.
Arindam Karmakar 《Information Processing Letters》2008,108(6):343-346
Here we propose an efficient algorithm for computing the smallest enclosing circle whose center is constrained to lie on a query line segment. Our algorithm preprocesses a given set of n points P={p1,p2,…,pn} such that for any query line or line segment L, it efficiently locates a point c on L that minimizes the maximum distance among the points in P from c. Roy et al. [S. Roy, A. Karmakar, S. Das, S.C. Nandy, Constrained minimum enclosing circle with center on a query line segment, in: Proc. of the 31st Mathematical Foundation of Computer Science, 2006, pp. 765-776] have proposed an algorithm that solves the query problem in O(log2n) time using O(nlogn) preprocessing time and O(n) space. Our algorithm improves the query time to O(logn); but the preprocessing time and space complexities are both O(n2). 相似文献