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排序方式: 共有502条查询结果,搜索用时 15 毫秒
101.
Rapid leaf development drives the seasonal pattern of volatile organic compound (VOC) fluxes in a ‘coppiced’ bioenergy poplar plantation
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Federico Brilli Beniamino Gioli Silvano Fares Zenone Terenzio Donatella Zona Bert Gielen Francesco Loreto Ivan A. Janssens Reinhart Ceulemans 《Plant, cell & environment》2016,39(3):539-555
Leaves of fast‐growing, woody bioenergy crops often emit volatile organic compounds (VOC). Some reactive VOC (especially isoprene) play a key role in climate forcing and may negatively affect local air quality. We monitored the seasonal exchange of VOC using the eddy covariance technique in a ‘coppiced’ poplar plantation. The complex interactions of VOC fluxes with climatic and physiological variables were also explored by using an artificial neural network (Self Organizing Map). Isoprene and methanol were the most abundant VOC emitted by the plantation. Rapid development of the canopy (and thus of the leaf area index, LAI) was associated with high methanol emissions and high rates of gross primary production (GPP) since the beginning of the growing season, while the onset of isoprene emission was delayed. The highest emissions of isoprene, and of isoprene photo‐oxidation products (Methyl Vinyl Ketone and Methacrolein, iox), occurred on the hottest and sunniest days, when GPP and evapotranspiration were highest, and formaldehyde was significantly deposited. Canopy senescence enhanced the exchange of oxygenated VOC. The accuracy of methanol and isoprene emission simulations with the Model of Emissions of Gases and Aerosols from Nature increased by applying a function to modify their basal emission factors, accounting for seasonality of GPP or LAI. 相似文献
102.
The ultrastructural organization of vegetative hyphae ofTuber albidum, an ectomycorrhizal fungus is described. Three zones are recognized: 1) an apical zone with cytoplasmic vesicles; 2) a subapical zone with protoplasmic organelles; 3) a vacuolated zone. This organization corresponds in its main features to the pattern just described for rapidly growing fungi. 相似文献
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104.
Giuseppe Cassara Elisabetta Gianazza Pier Giorgio Righetti Silvano Poma Leonardo Vicentini Vieri Scortecci 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》1980,221(2):279-291
Pure bile, pancreatic and duodenal human juices have been analyzed by isoelectric focusing, either at rest or upon stimulation with caerulein. In rats, stimulation has also been performed with secretin. Twenty bands have been resolved and quantified in the pancreatic secretion. By developing zymograms, a number of isozymes have been identified: 6 isoamylases [pI's 7.2, 7.1 and 6.6 (major) and pI's 7.4, 6.7 and 5.8 (minor)], 3 lipases [pI's 7.0 and 6.8 (major) and 6.4 (minor)], two major alkaline proteases (pI's 9.8 and 8.4) and one major acidic protease (pI 4.3) and one band of RNAase activity (pI 8.6). The stimulation kinetics follow a mechanism according to Palade, indicating uniform response to secretogogues, parallel intracellular transport and parallel discharge of pancreatic exocrine proteins. 相似文献
105.
Vito Di Noto Roberto Zannetti Silvano Bresadola Antonio Marigo Carla Marega 《Inorganica chimica acta》1991,190(2)
The reaction of α-MgCl2 with boiling ethyl acetate affords MgCI2(CH3COOC2H5)2·
(CH3COOC2H5), which is obtained as crystals suitable for X-ray analysis only from the mother liquor. M=315.5, orthorhombic, space group P21221 (No. 18), a=25.077(3), b=8.616(1), c=7.345(1) Å, V=1587.0(3) Å3, Z=4, Dx=1.32 g cm−3,λ A(Mo Kα)=0.71069 Å, μ=4.17 cm−1, F(000)=664, T=298 K, observed reflections: 1667, R=0.059 and Rw=0.069. The structure is composed of polymeric chains of MgCl2(CH3COOC2H5)2 and the ethyl acetate molecules occupy a mutually trans position. 相似文献
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A M Martelli C Carini S Marmiroli M Mazzoni P J Barker R S Gilmour S Capitani 《Experimental cell research》1991,195(1):255-262
Comparison of protein kinase activity in normal and regenerating rat liver nuclei indicates that exogenous histone H1 is hyperphosphorylated in 22-h regenerating nuclei. The protein kinase involved is not sensitive to protein kinase A inhibitor, is inhibited by staurosporine and by an anti-PKC polyclonal antibody, utilizes only ATP, and also phosphorylates the C-terminal fragment of histone H1. These data suggest that protein kinase C is responsible for the observed effects, in agreement with the presence of this enzyme in normal and regenerating nuclei demonstrated by immunoblotting. 相似文献
108.
109.
Meo CD Panza L Capitani D Mannina L Banzato A Rondina M Renier D Rosato A Crescenzi V 《Biomacromolecules》2007,8(2):552-559
Boron neutron capture therapy (BNCT) represents a promising approach for tumor therapy. A critical requirement for BNCT is tumor targeting, a goal that is currently addressed with the development of low and high molecular weight agents capable of interacting with receptors expressed by cancer cells. Here, we describe a new bioconjugate (HApCB) composed by n-propyl carborane linked to hyaluronan (HA) via an ester linkage for a degree of substitution of approximately 30%, leading to a water-soluble derivative. The structure and main physicochemical characteristics of the new HA derivative were determined by means of Fourier transform infrared, fluorescence, and 1H, 13C, and 10B NMR analysis and are herein reported in detail. As HA is recognized by the CD44 antigen, densely populating the surface of many tumor cells, HApCB is expected to deliver boron atoms from the locally released carborane cages directly to target cells for antitumor application in BNCT. In vitro biological experiments showed that HApCB was not toxic for a variety of human tumor cells of different histotypes, specifically interacted with CD44 as the native unconjugated HA, and underwent uptake by tumor cells, leading to accumulation of amounts of boron atoms largely exceeding those required for a successful BNCT approach. Thus, HApCB may be regarded as a promising new BNCT agent for specific targeting of cancer cells overexpressing the CD44 receptor. 相似文献
110.
Rimondi E Secchiero P Quaroni A Zerbinati C Capitani S Zauli G 《Journal of cellular physiology》2006,206(3):647-654
Despite the fact that tumor necrosis factor (TNF)-related apoptosis inducing ligand (TRAIL) and its receptors (TRAIL-Rs) are expressed in intestinal mucosa, little is known about the biological role of this system in intestinal cell physiology. The expression of surface TRAIL and TRAIL-R1, -R2, -R3, -R4 were examined by flow cytometry in the immortalized human cell line tsFHI under culture conditions promoting growth or growth arrest and expression of differentiated traits. A progressive increase of surface TRAIL expression paralleled tsFHI differentiation, consistently with immunohistochemistry analysis showing an increase of TRAIL immunostaining along the crypt-villus axis in normal jejuneal mucosa. In spite of the presence of TRAIL-R1 and TRAIL-R2 "death receptors," recombinant TRAIL was not cytotoxic for tsFHI cells. Exposure of tsFHI to recombinant TRAIL rather increased/anticipated the expression levels of the cyclin-dependent kinase inhibitors p21 and p27, which mediate the induction of growth arrest and the stabilization of differentiated traits, respectively, as well as of the canonical differentiation marker DPPIV. The differentiation inducing activity of TRAIL was abolished by pre-incubation with a Fc-TRAIL-R2 chimera. On the other hand, TRAIL did not significantly modulate the levels of osteoprotegerin (OPG), CXCL8/IL-8, CXCL9/MIG, and CXCL10/IP10 spontaneously released or induced by inflammatory cytokines. Taken together, these data suggest that TRAIL might act as a paracrine trophic cytokine on intestinal epithelium, promoting intestinal cell differentiation. 相似文献