全文获取类型
收费全文 | 159篇 |
免费 | 8篇 |
专业分类
电工技术 | 7篇 |
化学工业 | 19篇 |
金属工艺 | 2篇 |
机械仪表 | 1篇 |
建筑科学 | 8篇 |
能源动力 | 8篇 |
轻工业 | 15篇 |
水利工程 | 2篇 |
无线电 | 7篇 |
一般工业技术 | 29篇 |
冶金工业 | 39篇 |
原子能技术 | 2篇 |
自动化技术 | 28篇 |
出版年
2023年 | 1篇 |
2022年 | 4篇 |
2021年 | 5篇 |
2020年 | 3篇 |
2019年 | 5篇 |
2018年 | 2篇 |
2017年 | 6篇 |
2016年 | 1篇 |
2015年 | 1篇 |
2014年 | 5篇 |
2013年 | 9篇 |
2012年 | 5篇 |
2011年 | 5篇 |
2010年 | 8篇 |
2009年 | 9篇 |
2008年 | 6篇 |
2007年 | 3篇 |
2006年 | 5篇 |
2005年 | 4篇 |
2004年 | 7篇 |
2003年 | 3篇 |
2002年 | 4篇 |
2001年 | 4篇 |
2000年 | 1篇 |
1999年 | 1篇 |
1998年 | 12篇 |
1997年 | 9篇 |
1996年 | 7篇 |
1995年 | 7篇 |
1994年 | 4篇 |
1993年 | 4篇 |
1992年 | 3篇 |
1991年 | 4篇 |
1990年 | 2篇 |
1989年 | 3篇 |
1988年 | 1篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1980年 | 2篇 |
排序方式: 共有167条查询结果,搜索用时 15 毫秒
41.
Jean Blaise Jean Vergès Jean-Fran?ois Wyart Rolf Engleman Jr 《Journal of research of the National Institute of Standards and Technology》1992,97(1):213-216
All known energy levels of neutral platinum (Pt I) are presented, including 119 new levels based on analysis of recent comprehensive observations of the spectrum. These results are taken from a detailed analysis of the spectrum to be published in Journal de Physique II. 相似文献
42.
E Troncy M Francoeur I Salazkin F Yang M Charbonneau G Leclerc P Vinay G Blaise 《Canadian Metallurgical Quarterly》1997,79(5):631-640
Whether radiofrequency (RF) fields are carcinogenic is controversial; epidemiological data have been inconclusive and animal tests limited. The aim of the present study was to determine whether long-term exposure to pulse-modulated RF fields similar to those used in digital mobile telecommunications would increase the incidence of lymphoma in E mu-Pim1 transgenic mice, which are moderately predisposed to develop lymphoma spontaneously. One hundred female E mu-Pim1 mice were sham-exposed and 101 were exposed for two 30-min periods per day for up to 18 months to plane-wave fields of 900 MHz with a pulse repetition frequency of 217 Hz and a pulse width of 0.6 ms. Incident power densities were 2.6-13 W/m2 and specific absorption rates were 0.008-4.2 W/kg, averaging 0.13-1.4 W/kg. Lymphoma risk was found to be significantly higher in the exposed mice than in the controls (OR = 2.4. P = 0.006, 95% CI = 1.3-4.5). Follicular lymphomas were the major contributor to the increased tumor incidence. Thus long-term intermittent exposure to RF fields can enhance the probability that mice carrying a lymphomagenic oncogene will develop lymphomas. We suggest that such genetically cancer-prone mice provide an experimental system for more detailed assessment of dose-response relationships for risk of cancer after RF-field exposure. 相似文献
43.
Wohwe Sambo Damien Yenke Blaise Omer Förster Anna Ndong Jospeh Dayang Paul Sarr Idrissa 《Wireless Networks》2022,28(7):3275-3292
Wireless Networks - Nowadays, the exploitation of Wireless Underground Sensor Networks (WUSNs) remains challenging because of the attenuation of wireless underground communications. This issue... 相似文献
44.
45.
Wallace Carmichael J.A.; Corth?sy Blaise E. 《Protein engineering, design & selection : PEDS》1986,1(1):23-27
We have used protein semisynthesis to prepare four analoguesof horse cytochrome c, in which the glutamic acid residue atposition 66 has been removed and replaced by norvaline, glutamine,lysine and, as a methodological control, glutamic acid. Thisresidue is quite strongly conserved in mitochondrial cytochromec, and forms part of a cluster of acidic residues that occursin all cytochromes c but whose function is obscure. Comparativestudies of the physical and biochemical properties of the analogueshave now disclosed two specific roles for Glu66 in the protein.It contributes significantly to the stabilization of the activeconformation of the protein, probably by salt bridge formation,and it appears to participate in the redox-state-dependent ATP-bindingsite of cytochrome c. Our results also support two general viewsof the role of surface charged residues in cytochrome c, namelythat their disposition influences both redox potential, throughthe electrostatic field felt at the redox centre, and the kineticsof electron transfer, through the dipole moment they generate. 相似文献
46.
Zhifei Xu Blaise Ravelo Olivier Maurice Sébastien Lalléchère Fayu Wan 《International Journal of Circuit Theory and Applications》2019,47(3):391-405
An analytical modeling method of symmetric tree interconnect is developed in this paper. The tree topology is composed of multibranch distributed interconnects of printed circuit board (PCB). The interconnects are constituted by elementary transmission line (TL) defined by its characteristic impedance and propagation constant. The star symmetric tree model is built with the Kron-Branin (KB) formalism elaborated with the graph topology. Reduction method allowing to simplify the graph from single-input multiple-output (SIMO) to single-input single-output (SISO) circuit is used. The interconnect tree branch currents are determined from the reduced SISO structure. The symmetric tree S-parameter and access and transfer impedance models are expressed in function of constituting elementary TL parameters with the KB formalism. The particular behaviors of short-circuit and open-ended star tree are investigated versus the tree number of output branches. The developed KB model effectiveness is validated with microstrip star tree designed and simulated with a 3D electromagnetic computational and electronic circuit designer commercial tool. Three different proofs of concept (POC) of star trees comprised of three-output, four-output, and five-output branches are computed. The simulated reflection and transmission coefficients from DC to 5 GHz are in good agreement with the KB models. The proposed model is potentially useful for the PCB complex interconnect modeling and signal integrity analysis. 相似文献
47.
S. Abdallah W. Karwowski R. Shell A. Sonbol E. Ravelo 《Theoretical Issues in Ergonomics Science》2013,14(6):551-564
Objective:?The objective of this research is to develop and validate general lifting equations based on the concept of mechanical work performed during the manual handling of objects. Background:?To the authors’ knowledge, the NIOSH lifting equation was based on an empirical approach. Therefore, there is a need for general lifting equations that are based on the laws of mechanics and physics. Methods:?General lifting equations were developed as a function of weight, horizontal distance in the sagittal plane, vertical travel distance, vertical distance from the floor to the origin of lift and angle of twist. The equations were based on the mechanical work required against gravity/friction, supplemented with stress coefficients to account for task difficulty not traditionally embedded in the dot product of gravity/friction forces and distance. Validation of the equations was performed with respect to the NIOSH lifting equation. Results:?Results indicate that the general lifting index (GLI) was comparable to the NIOSH lifting index (LI) for different values of horizontal distance, vertical travel distance, twisting angle and vertical height at origin of lift. On the other hand, the GLI is more sensitive (i.e. larger) to individual changes in vertical travel distance or vertical height at origin of lift in comparison to the NIOSH LI. Consequently, the effect of horizontal distance was dampened in the GLI. Conclusion:?The empirical approach inherent in human expertise, which was used by NIOSH in the development of their lifting equation, appears to be a good approximation on the basis of physics and mechanics laws. As originally planned by NIOSH, the lifting equation appears to be protective of the general workforce. Furthermore, the lifting equations hold the promise of assisting in the estimation of peak and cumulative lifting stresses in the workplace. 相似文献
48.
Antioxidant activity of Sonoran Desert bee pollen 总被引:3,自引:0,他引:3
Bee pollen (pollen collected by honey bees) was collected in the high intensity ultraviolet (UV) Sonoran Desert and analyzed by the DPPH (radical 2,2-diphenyl-1-picryhydrazyl) assay and the FRAP (ferric reducing-antioxidant power) assay on six different pollen samples and in eight different water miscible solvents at 50 mg/ml. The bee pollen taxa were characterized for each pollen type by acetylization of the pollen extracts followed by microscopy and comparison with a library of samples native to the Sonoran Desert. The standards (R-(+)-6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid), known as TROLOX, gallic acid and α-tocopherol (vitamin E) were analysed as standards to determine the potency of each pollen sample in the most efficient solvent. The Mimosa pollen sample displayed the highest antioxidant activity. Total polyphenolics, flavanols, flavones were determined, and the results are reported in milligrams of gallic acid, quercetin and naringenin per gram of pollen, respectively. There was good correlation between antioxidant activity and total phenolics. The order of effectiveness of the pollen samples in regard to antioxidant activity was determined and the most effective extraction solvents are discussed. Finally, solid phase micro-extraction, coupled with gas chromatography–mass spectroscopy was utilized to identify and quantify polyphenolic compounds known to have free radical scavenging activity in the pollen samples. 相似文献
49.
The applicability of a gold-plated iridium Nano-Band array ultramicroelectrode (6 microm by 0.2 microm, 64-microm interspacing, 100 electrode bands) in the analysis of mercury using a portable system is demonstrated by anodic stripping voltammetry in real-life samples. Optimized measurement parameters, 0.1 M HCl electrolyte, plating potential of 0 mV, and staircase scan mode were identified. The dynamic linear range is 10-180 ppb at 5-s deposition time with 1.5 microC of gold plated. The experimental detection limit for Hg2+ in 0.1 M HCl was 0.5 ppb at a deposition time of 4 min and a scan rate of 10 V/s. Real-life samples, such as flue gas exposed samples from flue gas simulators could be analyzed within 5 min using the method of standard additions. We identified a field-portable extraction procedure for soil samples using 1:1 concentrated HNO3/30% H2O2 mixture, compatible with ASV and the iridium electrode. The detection limit for soils is 1 ppm. The results obtained using ASV are in good agreement with reference values using cold vapor atomic absorption for the sample matrixes studied here. To our knowledge, this is the first mercury application using a reusable iridium array ultramicroelectrode. The portable potentiostat is less than 500 g, and together with the portable digestion method, makes the Nano-Band Explorer system field applicable. 相似文献
50.
Identity-creators and image-makers: Using citation analysis and thick description to put authors in their place 总被引:1,自引:0,他引:1
We describe the steps involved in constructing authors" citation identities (whom they cite) and citation images (who cites them). Familiarity with the intellectual, social, and institutional connections of these authors over time helps inform the analysis and augment the specificity of citation counts. Our study shows that authors" writing and referencing styles constitute a form of watermark for their scholarly output. 相似文献