全文获取类型
收费全文 | 253篇 |
免费 | 33篇 |
国内免费 | 7篇 |
专业分类
化学 | 97篇 |
力学 | 10篇 |
综合类 | 1篇 |
数学 | 47篇 |
物理学 | 138篇 |
出版年
2024年 | 1篇 |
2023年 | 1篇 |
2022年 | 9篇 |
2021年 | 3篇 |
2020年 | 8篇 |
2019年 | 3篇 |
2018年 | 5篇 |
2017年 | 6篇 |
2016年 | 14篇 |
2015年 | 11篇 |
2014年 | 17篇 |
2013年 | 21篇 |
2012年 | 14篇 |
2011年 | 13篇 |
2010年 | 19篇 |
2009年 | 17篇 |
2008年 | 16篇 |
2007年 | 15篇 |
2006年 | 13篇 |
2005年 | 5篇 |
2004年 | 13篇 |
2003年 | 8篇 |
2002年 | 12篇 |
2001年 | 8篇 |
2000年 | 6篇 |
1999年 | 1篇 |
1998年 | 4篇 |
1997年 | 11篇 |
1996年 | 1篇 |
1995年 | 3篇 |
1994年 | 2篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 5篇 |
1981年 | 1篇 |
排序方式: 共有293条查询结果,搜索用时 0 毫秒
81.
The fuel ion temperature in inertial confinement fusion can be determined from the neutron energy spectrum. For the implosion experiment with low neutron yield, and thus low signal-to-noise ratio, a new technique to unfold the neutron energy spectrum from the observed neutron time-of-flight signal is presented in this paper. This method uses a low-pass filter to remove noise from the signal with a threshold value determined by power spectrum analysis. This technique has been applied to the analysis of the observed neutron time-of-flight signals in the indirect drive implosion experiment conducted on Shenguang III prototype laser facility, and fuel ion temperatures of about 1.0 keV are obtained. 相似文献
82.
In the paper, a multiframe blind image deconvolution method based on total variation and framelet regularizer is proposed. An adapted version of the split Bregman method is proposed to efficiently solve the resulting minimization problems. In each iteration, four sub-problems need to be solved, one of which can be very efficiently and easily solved via fast Fourier transform implementation or closed form solution. Both simulated noisy and blurred frames and real degraded frames are used to verify the effectiveness of the proposed method. Comparative experimental results show that the proposed method can efficiently remove the blur and noises and restore high quality sharp image. 相似文献
83.
This paper deals with estimation of parameters for motion blurred images. The objectives are to estimate the length (L) and the blur angle (θ) of the given degraded image as accurately as possible so that the restoration performance can be optimised. Gabor filter is utilized to estimate the blur angle whereas a trained radial basis function neural network (RBFNN) estimates the blur length. Once these parameters are estimated the conventional restoration is performed. To validate the proposed scheme, simulation has been carried out on standard images as well as in real images subjected to different blur angles and lengths. The robustness of the scheme is also validated in noise situations of different strengths. In all situations, the results have been compared with standard schemes. It is in general observed that the proposed scheme outperforms its counterparts in terms of restoration parameters and visual quality. 相似文献
84.
Hand shake blurry image is a common phenomenon in our daily life. In this paper, a novel blind deconvolution scheme is proposed to recover a single hand shake blurry image. The algorithm is subdivided into two main stages, kernel estimation stage and non-blind deconvolution stage. In the kernel estimation stage, we propose a cost function taking a selected map into consideration. In the non-blind decovolution stage, another cost function is designed using image derivatives prior. We also present an adaptive kernel size selection method instead of traditional manual selection. Extensive experiments on real world blurry images are conducted to demonstrate the performance of our algorithm. 相似文献
85.
The probability density function (pdf) valid for the Gaussian case is often applied for describing the convolutional noise pdf in the blind adaptive deconvolution problem, although it is known that it can be applied only at the latter stages of the deconvolution process, where the convolutional noise pdf tends to be approximately Gaussian. Recently, the deconvolutional noise pdf was approximated with the Edgeworth Expansion and with the Maximum Entropy density function for the 16 Quadrature Amplitude Modulation (QAM) input but no equalization performance improvement was seen for the hard channel case with the equalization algorithm based on the Maximum Entropy density function approach for the convolutional noise pdf compared with the original Maximum Entropy algorithm, while for the Edgeworth Expansion approximation technique, additional predefined parameters were needed in the algorithm. In this paper, the Generalized Gaussian density (GGD) function and the Edgeworth Expansion are applied for approximating the convolutional noise pdf for the 16 QAM input case, with no need for additional predefined parameters in the obtained equalization method. Simulation results indicate that improved equalization performance is obtained from the convergence time point of view of approximately 15,000 symbols for the hard channel case with our new proposed equalization method based on the new model for the convolutional noise pdf compared to the original Maximum Entropy algorithm. By convergence time, we mean the number of symbols required to reach a residual inter-symbol-interference (ISI) for which reliable decisions can be made on the equalized output sequence. 相似文献
86.
87.
Yuan Zhen ZHOU Jian Bin ZHENG 《中国化学快报》2006,17(3):380-382
Fourier self-deconvolution (FSD) for resolving overlapped bands was originally developed by Kauppinent et al. in 19811–3. Unfortunately, the conceptual simplicity of FSD is counterbalanced by a number of failings4. Firstly, linear function for deconvolut… 相似文献
88.
This is the first time that the water‐dragging ability of aromatic compounds partitioning in octanolwater biphasic systems is experimentally estimated by a quantitative spectral deconvolution model. The water‐dragging amount, Δ f value, measured by the quantitative model is based on the integrations of peak area increments of component peaks deconvoluted from O‐H modes of water and octanol molecule, recorded by a Fourier‐transformed infrared spectrophotometer. The stoichiometry hydration capacity, Δ fw, is derived from the corresponding Δ f values. Without any tedious experimental procedure or complicated modeling calculation, the Δ fw value is able to give the required solute‐water hydration information. Such an advantage can't be provided by other techniques applied in the field of water‐dragging ability investigation. Six aromatic compounds were used for the method validation. The Δ fw data obtained by this model are generally consistent with literature‐known values. The efficiency of this quantitative spectral deconvolution model can solve the state of aggregations and the structure of hydrates existing in the organic phase. Moreover, this deconvolution model also has the ability to be extended further to investigate the environmental and biological problems related to the organic chemical portioning in the aqueous and non‐aqueous phases. 相似文献
89.
Refat Abdel-Hamid 《Monatshefte für Chemie / Chemical Monthly》1988,119(4):429-438
The electrochemical reduction of phenolphthalein in dimethylformamide solution containing 0.1 mol dm–3 tetraethylammonium perchlorate at the hanging dropping mercury electrode showed an irreversible two-electron voltammetric peak. It was found that the CV peak is diffusion-controlled at low concentrations (0.4 mmol dm–3). At higher concentration (0.5 mmol dm–3) a postpeak was developed besides the diffusion-controlled one which was assigned to the adsorbed depolarizer. Cyclic voltammetric studies indicate that phenolphthalein follows an ECEC mechanism. Convolution and deconvolution potential sweep voltammetry confirm that mechanism.
Mechanismus der voltametrischen Reduktion von Phenolphthalein an der Quecksilberelektrode inDMF
Zusammenfassung Die elektrochemische Reduktion von Phenolphthalein an der tropfenden Quecksilberelektrode in Dimethylformamidlösung mit einem Gehalt von 0.1 mol dm–3 an Tetraethylammoniumperchlorat zeigte ein irreversibles voltametrisches Maximum für zwei Elektronen. Es zeigte sich, daß der CV-Peak bei niederen Konzentrationen (0.4 mmol dm–3) diffusionskontrolliert ist. Bei höheren Konzentrationen (0.5 mmol dm–3) entwickelte sich ein nachkommendes Maximum neben dem diffusionskontrollierten, welches dem adsorbierten Depolarisator zugeordnet wurde. Untersuchungen mittels cyclischer Voltametrie zeigten, daß Phenolphthalein einem ECEC-Mechanismus folgt. Konvolutions-und Dekonvolutions-Potential-Sweep-Voltametrie bestätigten diesen Mechanismus.相似文献
90.
Jaroslav Blaško Róbert Kubinec Ivan Ostrovský Eva Pavlíková Ján Krupčík Ladislav Soják 《Journal of chromatography. A》2009,1216(14):2757-2761
A generally known problem of GC separation of trans-7;cis-9; cis-9,trans-11; and trans-8,cis-10 CLA (conjugated linoleic acid) isomers was studied by GC–MS on 100 m capillary column coated with cyanopropyl silicone phase at isothermal column temperatures in a range of 140–170 °C. The resolution of these CLA isomers obtained at given conditions was not high enough for direct quantitative analysis, but it was, however, sufficient for the determination of their peak areas by commercial deconvolution software. Resolution factors of overlapped CLA isomers determined by the separation of a model CLA mixture prepared by mixing of a commercial CLA mixture and CLA isomer fraction obtained by the HPLC semi-preparative separation of milk fatty acids methyl esters were used to validate the deconvolution procedure. Developed deconvolution procedure allowed the determination of the content of studied CLA isomers in ewes’ and cows’ milk samples, where dominant isomer cis-9,trans-11 is eluted between two small isomers trans-7,cis-9 and trans-8,cis-10 (in the ratio up to 1:100). 相似文献