全文获取类型
收费全文 | 238篇 |
免费 | 12篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 3篇 |
化学工业 | 54篇 |
金属工艺 | 2篇 |
机械仪表 | 2篇 |
建筑科学 | 5篇 |
能源动力 | 1篇 |
轻工业 | 9篇 |
石油天然气 | 1篇 |
无线电 | 39篇 |
一般工业技术 | 44篇 |
冶金工业 | 35篇 |
自动化技术 | 56篇 |
出版年
2024年 | 2篇 |
2023年 | 2篇 |
2022年 | 2篇 |
2021年 | 13篇 |
2020年 | 6篇 |
2019年 | 5篇 |
2018年 | 6篇 |
2017年 | 3篇 |
2016年 | 6篇 |
2015年 | 7篇 |
2014年 | 4篇 |
2013年 | 14篇 |
2012年 | 10篇 |
2011年 | 11篇 |
2010年 | 16篇 |
2009年 | 13篇 |
2008年 | 5篇 |
2007年 | 10篇 |
2006年 | 11篇 |
2005年 | 5篇 |
2004年 | 11篇 |
2003年 | 13篇 |
2002年 | 10篇 |
2001年 | 4篇 |
2000年 | 2篇 |
1999年 | 6篇 |
1998年 | 1篇 |
1997年 | 5篇 |
1996年 | 1篇 |
1995年 | 4篇 |
1994年 | 2篇 |
1993年 | 6篇 |
1992年 | 5篇 |
1991年 | 2篇 |
1990年 | 4篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1987年 | 3篇 |
1986年 | 2篇 |
1985年 | 3篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 3篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1975年 | 2篇 |
1967年 | 2篇 |
排序方式: 共有251条查询结果,搜索用时 15 毫秒
111.
The present study provides a first attempt to estimate the validity of the Guilty Knowledge Test (GKT) in real-life criminal investigations. Skin resistance responses in GKT records of 50 innocent and 48 guilty Ss, for whom actual truth was established by confession, were analyzed by two methods. On the basis of an a priori decision rule, 98% of the innocent and 42% of the guilty Ss were correctly classified. Signal detection measures based on various possible decision rules indicated that the distribution of guilty Ss was highly differentiated from the distribution of innocent Ss. An optimal decision rule yielded correct classifications for 94% of the innocent Ss and 65% of the guilty Ss. These results suggest that the GKT could be a useful investigative tool that protects innocent suspects from being falsely classified as guilty. The false-negative identifications were accounted for in terms of the realistic conditions. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
112.
113.
114.
The purpose of this paper is to study the loss probabilities of messages in an M/M/1/K queueing system where in addition to losses due to buffer overflow there are also random losses in the incoming and outgoing links. We focus on the influence of adding redundant packets to the messages (as in error correction coding, e.g. Reed–Solomon code, etc.). In the first part we use multi-dimensional probability generating functions for solving the recursions which generalize those introduced by Cidon et al. [IEEE Trans. Inform. Theory 39 (1) (1993) 98] for computing the loss probabilities and derive analytical formulae for a special case. In the second part of the paper we use combinatorial arguments and Ballot theorem results to alternatively obtain the loss probabilities. The analytical results allow us to investigate when does adding redundancy decrease the loss probabilities. 相似文献
115.
By measuring the threshold voltage of the structure for several drawn channel lengths, ΔL is extracted. This technique is the translation of a capacitance measurement into a threshold measurement and as such is accurate and simple to perform. Since the technique does not involve a current flow through the transistor under test, it is especially advantageous for L eff measurements on lightly-doped drain (LDD) and double-diffused drain (DDD) short-channel devices 相似文献
116.
We investigate a class of Markov-modulated stochastic recursive equations. This class includes multi-type branching processes with immigration as well as linear stochastic equations. Conditions are established for the existence of a stationary solution and expressions for the first two moments of this solution are found. Furthermore, the transient characteristics of the stochastic recursion are investigated: we obtain the first two moments of the transient solution as well. Finally, to illustrate our approach, the results are applied to the performance evaluation of packet forwarding in delay-tolerant mobile ad-hoc networks. 相似文献
117.
The low Earth orbit (LEO) environment is considered hazardous to spacecraft, resulting in materials degradation. Currently, in order to evaluate the degradation of materials in LEO, a retrieval of space exposed samples is required. In this study, a novel approach is proposed to evaluate degradation of materials in LEO without the need of retrieval. The method is utilizing photovoltaic cells (PVCs), an existing component onboard of any satellite. The PVCs are coated by various materials which are sensitive to different LEO constituents, such as atomic oxygen (AO) or ultra-violet (UV) radiation. The method's acronym is ORMADD (on-ORbit MAterials Degradation Detector). The ORMADD's principle of operation is based on measuring the PVC output power which depends on the cell coating material's optical transmission. Erosion of the coating by AO or coloring due to UV radiation affects its optical transmission and, accordingly, the PVC output. The ORMADD performance was tested using different coatings, such as polyimide and amorphous carbon (sensitive to AO), and siloxane based coating which is sensitive to UV radiation. The proposed ORMADD reveals sensitivity to different LEO components and can be used either as material degradation detector or as an AO monitor. 相似文献
118.
Xiaojie Liu Henna Popli Ohyun Kwon Hans Malissa Xin Pan Bumwoo Park Byoungki Choi Sunghan Kim Eitan Ehrenfreund Christoph Boehme Z. Valy Vardeny 《Advanced materials (Deerfield Beach, Fla.)》2020,32(48):2004421
The isotope effect is studied in the magneto-electroluminescence (MEL) and pulsed electrically detected magnetic resonance of organic light-emitting diodes based on thermally activated delayed fluorescence (TADF) from donor–acceptor exciplexes that are either protonated (H) or deuterated (D). It is found that at ambient temperature, the exchange of H to D has no effect on the spin-dependent current and MEL responses in the devices. However, at cryogenic temperatures, where the reverse intersystem crossing (RISC) from triplet to singlet exciplex diminishes, a pronounced isotope effect is observed. These results show that the RISC process is not governed by the hyperfine interaction as thought previously, but proceeds through spin-mixing in the triplet exciplex. The observations are corroborated by electrically detected transient spin nutation experiments that show relatively long dephasing time at ambient temperature, and interpreted in the context of a model that involves exchange and hyperfine interactions in the spin triplet exciplex. These findings deepen the understanding of the RISC process in TADF materials. 相似文献
119.
Ori Izhak Rosenberg 《Journal of Modern Optics》2020,67(13):1197-1209
This paper reports a straightforward technique for three-dimensional (3D) visualization of a flow profile by a hybrid algorithm combining Fourier transform orthogonal fringe projection and laser speckle imaging techniques. The use of orthogonal projection aims to suppress the zero order allowing surface reconstruction with high spatial resolution and accuracy while analyzing the intensity fluctuations of diffuse backscattered laser light providing 2D flow information. Once both are achieved, 3D flow visualization can be displayed. The method is experimentally validated first with a plastic tube filled with scattering liquid (milk) running at various controlled flow rates and then with the tube embedded under scattering layers (chicken breast) of varying thickness. The system includes a single, common camera, a commercial projector (profilometry channel), a laser light source (flow channel), and a computer station. In addition, orthogonal projection processing was combined with Hilbert transform, increasing the visualization and resolution of the measured flow profile. 相似文献
120.
Seven lignins from different sources were pyrolysed (i) isothermally in vacuum over the temperature range 300–1300 °C and (ii) at a constant heating rate of 30 °C min?1 and a pressure of 0.1 MPa over the temperature range 150–900 °C. The mass fraction of each product—char, tar and gas species—and the elemental composition of the char and the tar were determined for the flash pyrolysis experiments. The evolution rates of the gas species and the tar versus the dynamic temperature of pyrolysis were determined for the constant heating rate pyrolysis experiments. Although the amount of each product species varied from lignin to lignin, the evolution rates were insensitive to the lignin source and the extraction process. To model the data, modifications were made to a recently developed model of coal pyrolysis. The model proved to be successful in simulating both the data from vacuum flash pyrolysis and constant heating rate pyrolysis of Iotech lignin. 相似文献