全文获取类型
收费全文 | 56篇 |
免费 | 1篇 |
专业分类
电工技术 | 1篇 |
化学工业 | 5篇 |
机械仪表 | 1篇 |
建筑科学 | 6篇 |
轻工业 | 9篇 |
无线电 | 14篇 |
一般工业技术 | 11篇 |
冶金工业 | 5篇 |
原子能技术 | 2篇 |
自动化技术 | 3篇 |
出版年
2020年 | 2篇 |
2015年 | 1篇 |
2013年 | 3篇 |
2012年 | 1篇 |
2011年 | 4篇 |
2010年 | 3篇 |
2009年 | 4篇 |
2008年 | 4篇 |
2007年 | 2篇 |
2006年 | 5篇 |
2005年 | 1篇 |
2004年 | 3篇 |
2003年 | 3篇 |
2002年 | 5篇 |
2001年 | 2篇 |
1999年 | 1篇 |
1998年 | 1篇 |
1995年 | 2篇 |
1994年 | 2篇 |
1991年 | 2篇 |
1988年 | 1篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1982年 | 1篇 |
排序方式: 共有57条查询结果,搜索用时 31 毫秒
1.
A novel way of approaching wave propagation in two-dimensional (2-D) photonic crystal guides with finite length is presented. It is shown that the main propagation features can be captured by borrowing simple concepts of propagation in transmission lines and combining them with other concepts taken from the theory of periodic structures 相似文献
2.
P Boscolo M Di Gioacchino M Cervone F Di Giacomo P Bavazzano G Giuliano 《Canadian Metallurgical Quarterly》1995,17(1-6):27-31
Lymphocyte subpopulations were studied in 31 men working in a plant producing plastic materials in relation with control groups of similar age and smoking habit. 8 workers (group A) were exposed to solvents (mainly methylethylketone and dimethylformamide), 8 men (group B) to dust containing particles of calcium carbonate, polyvinylchloride, phtalates, unsaturated oils, paraffin wax, iron oxides, titanium bioxides, barium, zinc and lead and 15 men (group C), working in the same department as group B, were studied after a period of 16 months during which lead chromate was employed in the preparation of colors. The lymphocyte subpopulations were normal in group A, while in B there was a significant increase of HLA-DR + cells (monocytes, B and activated T lymphocytes). In group C, T helper/inducer lymphocytes (mainly CD4(+)-CD45RO- "virgin" lymphocytes), CD19+ B lymphocytes, CD3-HLADR+ and CD3-CD25+ (activated B lymphocytes and monocytes) were significantly reduced without changes of serum IgM, IgG and IgA. Highly significant correlation was found between B lymphocytes (reduced in the workers about 40%) and CD4(+)-CD45R0+ "memory" lymphocytes (reduced about 20%). Moreover, blood lead (correlated with urinary chromium) showed a highly significant negative correlation with the B lymphocytes. This study demonstrates that combined exposure to toxic agents produces specific modifications in the lymphocyte subsets without changes in immunoglobulins and confirms the results of previous researches showing that the exposure to lead or chromate induces reduction of lymphocytes in the peripheral blood. 相似文献
3.
Independent component analysis based on nonparametric density estimation 总被引:12,自引:0,他引:12
In this paper, we introduce a novel independent component analysis (ICA) algorithm, which is truly blind to the particular underlying distribution of the mixed signals. Using a nonparametric kernel density estimation technique, the algorithm performs simultaneously the estimation of the unknown probability density functions of the source signals and the estimation of the unmixing matrix. Following the proposed approach, the blind signal separation framework can be posed as a nonlinear optimization problem, where a closed form expression of the cost function is available, and only the elements of the unmixing matrix appear as unknowns. We conducted a series of Monte Carlo simulations, involving linear mixtures of various source signals with different statistical characteristics and sample sizes. The new algorithm not only consistently outperformed all state-of-the-art ICA methods, but also demonstrated the following properties: 1) Only a flexible model, capable of learning the source statistics, can consistently achieve an accurate separation of all the mixed signals. 2) Adopting a suitably designed optimization framework, it is possible to derive a flexible ICA algorithm that matches the stability and convergence properties of conventional algorithms. 3) A nonparametric approach does not necessarily require large sample sizes in order to outperform methods with fixed or partially adaptive contrast functions. 相似文献
4.
I. Raffeis U. Vroomen F. Adjei-Kyeremeh D. Großmann H. Hammelrath E. Westhoff S. Bremen D. Boscolo Bozza A. Bührig-Polaczek 《Materialwissenschaft und Werkstofftechnik》2020,51(4):432-444
A methodology is presented that compares the microstructural and mechanical properties of as-cast and additive-made ferritic-austenitic duplex steel 1.4517. Microstructure of approximately equal amounts of ferrite and austenite measured in as-cast material could not be replicated in post heat-treated laser powder bed fusion samples after 30 min and 60 min of post heat treatment. This is attributed to nitrogen loss during powder atomization which left fewer austenite formers. Post-heat treated laser powder bed fusion samples of duplex structure had its austenite content repeatedly adjusted between 38 % and 40 %. As-built laser powder bed fusion tensile specimens which had a ferritic microstructure recorded high tensile and yield strength but had very poor elongation. Post heat-treated duplex laser powder bed fusion tensile specimen built in both horizontal and vertical orientations had good tensile and yield strength comparable to conventional casting processes; Tensile strength – 739 MPa (horizontal), 759 MPa (vertical); Yield strength (Rp0.2) – 489 MPa (horizontal), 525 MPa (vertical). The horizontally built duplex specimen had a very high elongation of 32 % than the vertical (11 %) or conventionally reported (22 %). This work establishes the 1.4517 duplex steel as a good candidate with good mechanical properties when processed by additive manufacturing. 相似文献
5.
6.
Dynamic stiffness elements for plates are developed using first order shear deformation theory to carry out exact free vibration analysis of plate assemblies. The analysis has been facilitated by the application of Hamiltonian mechanics and symbolic computation. The Wittrick–Williams algorithm has been used as the solution technique. Results have been extensively validated using published literature for both uniform and non-uniform plates. Some finite element results are also provided. The accuracy and computational efficiency of the method are demonstrated. In the final part of the investigation, significant plate parameters are varied and their subsequent effects on the free vibration characteristics are studied. 相似文献
7.
In this letter, we numerically demonstrate that the use of inline nonlinear optical loop mirrors in strongly dispersion-managed transmission systems dominated by pulse distortion and amplitude noise can achieve all-optical passive 2R regeneration of a 40-Gb/s return-to-zero data stream. We define the tolerance limits of this result to the parameters of the input pulses 相似文献
8.
Piero De Filippis Monica Boscolo Mario Gibellini Paolo Rupena Fulvio Rubessa 《Drug development and industrial pharmacy》1991,17(14):2017-2028
The coprecipitates were prepared by a solvent technique using Eudragit E as carrier and indomethacin as a model drug.
X-Ray diffractometry, differential scanning calorimetry (DSC) and wettability tests were employed to investigate the physical state of the studied formulations. Up to 50% of indomethacin can be dispersed in an amorphous state in Eudragit E.
The influence of the pH on the in vitro release of solid dispersions has been evaluated. Because of the good solubility of Eudragit E at pH 1.2 a fast dissolution rate of the drug was observed while a marked delay was noticed at pH 7.5 where the polymer is only permeable to water. At pH 5.8 the kinetics of drug release can be modulated by the drug/polymer ratio. The dissolution rate of the drug can be increased by decreasing its amount in the coevaporate. 相似文献
X-Ray diffractometry, differential scanning calorimetry (DSC) and wettability tests were employed to investigate the physical state of the studied formulations. Up to 50% of indomethacin can be dispersed in an amorphous state in Eudragit E.
The influence of the pH on the in vitro release of solid dispersions has been evaluated. Because of the good solubility of Eudragit E at pH 1.2 a fast dissolution rate of the drug was observed while a marked delay was noticed at pH 7.5 where the polymer is only permeable to water. At pH 5.8 the kinetics of drug release can be modulated by the drug/polymer ratio. The dissolution rate of the drug can be increased by decreasing its amount in the coevaporate. 相似文献
9.
A 352-MHz one-cell photocathode electron gun is studied. The simulations with PARMELA are done with two values of peak accelerating fields: 21 and 10 MV/m. Three cavity profiles are compared. The results are also discussed in view of the previous analytic theory. The space-charge effect with peak current greater than 300 A covers the RF effect. The beam qualities are not sensitive to cavity design 相似文献
10.
Honsell G De Bortoli M Boscolo S Dell'Aversano C Battocchi C Fontanive G Penna A Berti F Sosa S Yasumoto T Ciminiello P Poli M Tubaro A 《Environmental science & technology》2011,45(16):7051-7059
Ostreopsis cf. ovata, a benthic dinoflagellate often blooming along the Mediterranean coasts, has been associated with toxic events ranging from dyspnea to mild dermatitis. In late September 2009, an Ostreopsis cf. ovata bloom occurred in the Gulf of Trieste (Northern Adriatic Sea; Italy), causing pruritus and mild dermatitis in beachgoers. An integrated study was initiated to characterize Ostreopsis cells by light and confocal microscopy, PCR techniques, immunocytochemistry, and high resolution liquid chromatography-mass spectrometry (HR LC-MS). The presence of Ostreopsis cf. ovata of the Atlantic/Mediterranean clade was unambiguously established by morphological and genetic analyses in field samples. Several palytoxin-like compounds (ovatoxin-a,-b,-c,-d,-e) were identified by HR LC-MS, ovatoxin-a being the most abundant (45-64 pg/cell). Surprisingly, no palytoxin was detected. For the first time, monoclonal and polyclonal antipalytoxin antibodies revealed the intracellular cytoplasmic localization of ovatoxins, suggesting their cross-reactivity with these antibodies. Since harmful dinoflagellates do not always produce toxins, the immunocytochemical localization of ovatoxins, although qualitative, can provide an early warning for toxic Ostreopsis cells before their massive diffusion and/or concentration in seafood. 相似文献