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排序方式: 共有1324条查询结果,搜索用时 15 毫秒
1.
Aard J. Groen Petra C. De WeerdNederhof Inge C. Kerssensvan Drongelen Rob A.J. Badoux Gerard P.H. Olthuis 《Creativity & Innovation Management》2002,11(1):2-16
In this paper we describe a framework for analysing the creation and justification of Research & Development. The 4S framework is developed for analysing the scope, scale, skills and social network aspects of Research & Development value. The framework is based on social system theory, a process contingency model, and recent Research & Development metrics. We present a first empirical assessment based on a workshop using the 4S framework for leveraging Research & Development. Results that assist in the assessment of value creation utilising R & D within networks are very relevant in high tech industries. The multi–dimensional process approach of this framework seems promising for understanding and managing R&D value creation, but needs further operationalisation. Case studies are described and a Dutch network on leveraging R&D has been initiated. 相似文献
2.
Space charge analysis in doped zinc phthalocyanine thin films 总被引:1,自引:0,他引:1
We present an improved method for the determination of the space charge density in organic semiconductors used as active layers in Schottky barriers. These measurements provide a powerful tool for the interpretation of basic properties such as the rectifying effect, doping process and carrier trapping mechanisms of films together with a way to assess the potential for sensor applications. Metal/molecular semiconductor Schottky junctions were prepared on zinc phthalocyanine layers doped by a controlled exposure to the ambient air. The organic material is deposited on aluminium or heavily doped silicon substrates, in order to make a Schottky barrier (film thickness around 1 μm). An ohmic contact is obtained by a gold deposition on the strongly doped side of the molecular material. We have investigated the current-voltage and capacitance-voltage characteristics. The results are interpreted in terms of a space charge region at the interface with the substrate, followed by an extended semi-insulating layer.The contribution of these two regions to the total impedance is analyzed in well improved conditions of measurements. 相似文献
3.
Gerard E. Lenain Herbert A. McKinstry Dinesh K. Agrawal 《Journal of the American Ceramic Society》1985,68(9):224-C
The X-ray diffraction pattern for potassium-zirconium phosphate is significantly improved when the material is prepared by the sol-gel route rather than the powder method. Peaks at high, low, and intermediate angles are presented and compared for the two methods. It is assumed that the more nearly homogeneous mixing of the elements in the sol-gel process is responsible for the significant improvement in crystallinity. 相似文献
4.
J Gerard LavinShekhar Subramoney Rodney S RuoffSavas Berber David Tománek 《Carbon》2002,40(7):1123-1130
Recent high-resolution transmission electron microscopy (HREM) studies of multiwalled carbon nanotubes (MWCNTs) reveal a class of defects analogous to edge dislocations in a crystal. These defects are believed to mark the transition from scrolls on one side to nested tubes on the other. On the tube side, layer spacing becomes irregular. Analysis of the helicity of the tubes shows a strong correlation between diameter and helicity. This suggests that the organizing principle for the tubes is not Van der Waals forces, as in the case of graphite or turbostratic carbon, but preservation of helicity. Based on these observations and total energy calculations, the authors speculate that graphene monolayers initially form scrolls and subsequently transform into multiwall nanotubes through the progression of defects. Scrolls and nested tubes thus coexist within a single MWNT. 相似文献
5.
Ulrich Schmatz Catherine Dubourdieu Oleg Lebedev Gerard Delabouglise Francois Weiss Jean-Pierre Senateur 《Journal of Low Temperature Physics》1996,105(5-6):1301-1306
Thin and thick YBCO Films have been grown by Aerosol Assisted as well as by thermal MOCVD. The Aerosol Assisted MOCVD technique allows the growth of YBCO films from a single liquid source at deposition rates of up to 10m/h.Transport measurements (I-V) on etched microbridges using a single pulse technique have been performed. The angular magnetic field dependence Jc() of the critical current density from Tc down to 50 K has been measured. Transport properties are reported and discussed with respect to the microstructural features as determined by X-ray diffraction and electron microscopy. 相似文献
6.
No Heading We present vibrating wire viscometer experiments in concentrated and dilute 3He-4He mixtures showing that the slip length may become orders of magnitude larger than the mean free path due to increased specular scattering of the 3He quasiparticles with the superfluid 4He film on the wire. The experimental results are in good agreement with a recent theory for slip which accounts for the cylindrical geometry of the wire and for velocity slip in directions normal as well as tangential to the surface of the wire.PACS numbers: 67.60.Fp, 51.20.+d 相似文献
7.
夹杂物问题应力场的数值计算 总被引:3,自引:1,他引:3
等效夹杂物方法是细观力学中的一种重要方法,文中编制的数值计算程序能在考虑多个夹杂物相互响应的情况下计算材料应力、应变场,并实现了计算结果的三维显示.计算结果与文献中的计算结果非常吻合.本文编制的数值计算程序不仅可以用于研究复合材料的损伤演化及失效,而且利用特殊构型的椭球空洞来模拟裂纹,可以计算裂纹群的应力、应变场。 相似文献
8.
Manuel Serrano Gerard Espinosa Antonio Serrano Ricard Cervera 《International journal of molecular sciences》2022,23(9)
High prevalence of both criteria and extra-criteria antiphospholipid antibodies (aPL) has been reported in COVID-19 patients. However, the differences in aPL prevalence decreased when an age-matched control group was included. The association of aPL with thrombotic events in COVID-19 is very heterogeneous. This could be influenced by the fact that most of the studies carried out were conducted on small populations enriched with elderly patients in which aPL was measured only at a single point and they were performed with non-standardized assays. The few studies that confirmed aPL in a second measurement showed that aPL levels hardly changed, with the exception of the lupus anticoagulant that commonly reduced. COVID-19 coagulopathy is an aPL-independent phenomenon closely associated with the onset of the disease. Thrombosis occurs later in patients with aPL presence, which is likely an additional prothrombotic factor. B2-glycoprotein deficiency (mainly aPL antigen caused both by low production and consumption) is very common during the SARS-CoV2 infection and has been associated with a greater predisposition to COVID-19 complications. This could be a new prothrombotic mechanism that may be caused by the blockage of its physiological functions, the anticoagulant state being the most important. 相似文献
9.
Zuopeng Wu Rebecca A. Sweet Gerard F. Hoyne Charmaine J. Simeonovic Christopher R. Parish 《International journal of molecular sciences》2022,23(9)
It has been accepted for decades that T lymphocytes and metastasising tumour cells traverse basement membranes (BM) by deploying a battery of degradative enzymes, particularly proteases. However, since many redundant proteases can solubilise BM it has been difficult to prove that proteases aid cell migration, particularly in vivo. Recent studies also suggest that other mechanisms allow BM passage of cells. To resolve this issue we exploited heparanase-1 (HPSE-1), the only endoglycosidase in mammals that digests heparan sulfate (HS), a major constituent of BM. Initially we examined the effect of HPSE-1 deficiency on a well-characterised adoptive transfer model of T-cell-mediated inflammation. We found that total elimination of HPSE-1 from this system resulted in a drastic reduction in tissue injury and loss of target HS. Subsequent studies showed that the source of HPSE-1 in the transferred T cells was predominantly activated CD4+ T cells. Based on bone marrow chimeras, two cellular sources of HPSE-1 were identified in T cell recipients, one being haematopoiesis dependent and the other radiation resistant. Collectively our findings unequivocally demonstrate that an acute T-cell-initiated inflammatory response is HPSE-1 dependent and is reliant on HPSE-1 from at least three different cell types. 相似文献
10.
Renata Reisfeld Tsiala Saraidarov Gerard Panzer Viktoria Levchenko Michael Gaft 《Optical Materials》2011,34(2):351-354
In our search for efficient Luminescent Solar Concentrators (LSC) we have prepared polyvinyl pyrrolidone (PVP) films incorporated by ethylenediamine tetraacetic acid (EDTA) complex of europium and co-doped with silver nanoparticles (NPs). Steady state fluorescence was studied under weak and strong excitation. Dynamical study was performed by second harmonic of Nd laser. Under weak excitation the fluorescence of europium co-doped with silver plasmons increased by a factor of three and excited by continuous laser by a factor of 50. The lifetimes of films doped by the complex were 755 μs and co-doped with silver nanoparticles 946 μs. This is the first finding that the photon density accumulates the number of plasmons interacting with electronic states of europium increasing its transition probability resulting in the strong intensification of fluorescence. In dynamical measurements of lifetimes a single pulse does not provide enough energy to create such number of plasmons. 相似文献