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131.
Alexander V. Kirdyanov Eugene A. Vaganov Malcolm K. Hughes 《Trees - Structure and Function》2007,21(1):37-44
We propose a technique for separating the climatic signal which is contained in two tree-ring parameters widely used in dendroclimatology.
The method is based on the removal of the relationship between tree-ring width (TRW) and maximum latewood density (MXD) observed
for narrow tree rings from high latitudes. The new technique is tested on data from three larch stands located along the northern
timberline in Eurasia. Correlations were calculated between the temperatures of pentads (five consecutive days), TRW chronologies
and MXD chronologies calculated according to the standard and proposed methods. The analysis confirms the great importance
of summer temperature for tree radial growth and tree-ring formation. TRW is positively correlated with the temperature of
four to eight pentads (depending on the region) at the beginning of the growth season, but MXD as obtained by the standard
technique is correlated with temperature over a much longer period. For maximum density series from which the relationship
between MXD and TRW has been removed (MXD′), there is a clear correlation with temperatures in the second part of the growing
season. These results are consistent with the known dynamics of tree-ring growth in high latitudes and mechanisms of tree-ring
formation. 相似文献
132.
Ya. O. Loginov G. G. Khudaigulov S. P. Chetverikov A. I. Melent’ev O. N. Loginov 《Applied Biochemistry and Microbiology》2011,47(3):311-314
Highly viscous polysaccharide (250–350 kDa) of an alginate nature with a predominance of α-L-guluronic acid (M/G = 0.22) was
obtained from Azotobacter vinelandi. The yield of polysaccharide was 20.5 ± 0.5 g/l when cultured in a medium containing molasses at a viscosity of the cultural
liquid of over 30000 cSt. The biopolymer is stable at pH 4.0–9.0 in a wide temperature range and well soluble in highly mineralized
water; it retains a high viscosity level and can be used in the petroleum industry for enhanced oil recovery. 相似文献
133.
I. A. Parfenov T. A. Revina P. P. Pashkovsky N. L. Radyukina T. A. Valueva 《Applied Biochemistry and Microbiology》2011,47(4):361-365
Product of polymerase chain reaction designated as PKPIJ-B was isolated after amplification from genomic DNA of potato (Solarium tuberosum L., Zhukov Jubilee cultivar) using the designed primers. Nucleotide sequence of PKPIJ-B was determined and amino acid sequence of protein was restored. Analysis of this sequence has allowed us to suggest that
isolated gene fragment encodes chymotrypsin and trypsin inhibitor protein (PKCI-23 potato Kunitz-type chymotrypsin inhibitor)
of potato tubers. 相似文献
134.
G. Ricci L. Volpi L. Pasquali L. Petrozzi G. Siciliano 《Journal of biological physics》2009,35(4):317-336
Astrocytes have long been considered as just providing trophic support for neurons in the central nervous system, but recently
several studies have highlighted their importance in many functions such as neurotransmission, metabolite and electrolyte
homeostasis, cell signaling, inflammation, and synapse modulation. Astrocytes are, in fact, part of a bidirectional crosstalk
with neurons. Moreover, increasing evidence is stressing the emerging role of astrocyte dysfunction in the pathophysiology
of neurological disorders, including neurodegenerative disease, stroke, epilepsy, migraine, and neuroinflammatory diseases. 相似文献
135.
Yu. N. Litvinov N. T. Erzhanov N. V. Lopatina T. Zh. Abylkhasanov 《Contemporary Problems of Ecology》2010,3(5):593-596
Small mammals were studied in the Kazakh Uplands in the spring and fall of 2008. The trapping studies revealed 10 species.
Abundances of the animals were low in the four main distinct characteristic biotopes of Bayanaul National Park, but those
of biotope dominants were high. In the Kazakh Uplands, rodents and insectivores are clearly restricted to certain biotopes.
Biodiversity indices for small mammal communities are low, indicating that the community structure is disturbed. 相似文献
136.
An experiment on acceleration and retardation of ontogeny with thyroid manipulation has revealed direct changes in definitive
dentition of pharyngeal bones in Abramis brama bream. As development rate accelerates, the number of teeth reduces to the formula 5-4. When development rate is retarded,
this number increases to the formula 6-5. Moreover, an additional minor row of teeth (1.6–5.1, 2.6–5.2) is formed. The observed
changes in tooth numbers exceed the known variability in natural populations of bream. It is assumed that heterochronies lead
to the changes in the number of teeth. 相似文献
137.
138.
Ratul Saha Robert S. Donofrio Susan T. Bagley 《Journal of industrial microbiology & biotechnology》2010,37(8):843-848
A TaqMan quantitative real-time polymerase chain reaction (qPCR) assay was developed for the detection and enumeration of
three Pseudomonas species belonging to the mendocina sublineage (P. oleovorans, P. pseudoalcaligenes, and P. oleovorans subsp. lubricantis) found in contaminated metalworking fluids (MWFs). These microbes are the primary colonizers and serve as indicator organisms
of biodegradation of used MWFs. Molecular techniques such as qPCR are preferred for the detection of these microbes since
they grow poorly on typical growth media such as R2A agar and Pseudomonas isolation agar (PIA). Traditional culturing techniques not only underestimate the actual distribution of these bacteria but
are also time-consuming. The primer–probe pair developed from gyrase B (gyrB) sequences of the targeted bacteria was highly sensitive and specific for the three species. qPCR was performed with both
whole cell and genomic DNA to confirm the specificity and sensitivity of the assay. The sensitivity of the assay was 101 colony forming units (CFU)/ml for whole cell and 13.7 fg with genomic DNA. The primer–probe pair was successful in determining
concentrations from used MWF samples, indicating levels between 2.9 × 103 and 3.9 × 106 CFU/ml. In contrast, the total count of Pseudomonas sp. recovered on PIA was in the range of <1.0 × 101 to 1.4 × 105 CFU/ml for the same samples. Based on these results from the qPCR assay, the designed TaqMan primer–probe pair can be efficiently
used for rapid (within 2 h) determination of the distribution of these species of Pseudomonas in contaminated MWFs. 相似文献
139.
M. I. Jsselstijn J. Kaiser F. L. van Delft H. E. Schoemaker F. P. J. T. Rutjes 《Amino acids》2003,24(3):263-266
Summary. Novel synthetic procedures for the modification of non-proteinogenic acetylene-containing amino acids have been developed.
The functionalization either proceeds via zinc/copper-mediated introduction of alkyl substituents, or via tungsten-catalyzed
ring-closing alkyne metathesis reactions.
Received March 28, 2002 Accepted October 3, 2002 Published online December 18, 2002
Acknowledgements These investigations are supported (in part) by the Netherlands Research Council for Chemical Sciences (CW) with financial
aid from the Netherlands Technology Foundation (STW).
Authors' address: Floris P. J. T. Rutjes, Prof. Dr., Department of Organic Chemistry, University of Nijmegen, Toernooiveld 1, NL-6525 ED Nijmegen,
The Netherlands, E-mail: rutjes@sci.kun.nl
2, selected data: 1H NMR (300 MHz, CDCl3) δ 5.32 (d, J = 7.7 Hz, 1H), 4.44–4.40 (m, 1H), 3.76 (s, 3H), 2.75–2.73 (d, J = 5.0 Hz, 2H), 1.44 (s, 9H); 13C NMR (75 MHz, CDCl3) δ 171.0, 155.0, 80.3, 74.6, 52.6, 51.9, 41.7, 28.3, 24.0; mp = 55°C.
Typical procedure for 5: zinc dust (116 mg, 1.408 mmol) was weighed into a 20 mL flask, which was repeatedly evacuated (with heating using a heat
gun) and flushed with argon. Dry DMF (0.5 mL, distilled from CaH2) and 1,2-dibromoethane (9.2 μL, 0.106 mmol) were added and the flask was heated at 80°C for 40 min. The reaction mixture was allowed to cool to room temperature,
trimethylsilyl chloride (4 μL, 0.035 mmol) was added and the resulting mixture was stirred vigorously for a further 30 min under argon. Iodocyclohexane
(69 μl, 0.528 mmol) was added and stirred at room temperature for 3 h more after which stirring was ceased to settle the zinc.
CuCN (41 mg, 0.458 mmol) and LiCl (40 mg, 0.915 mmol) were heated to 150°C for 2 h and cooled to room temperature. Addition
of DMF (1 mL) formed a soluble CuCN·2LiCl complex within 5 min. After cooling the Cu-complex to −15°C, the organozinc reagent
was added dropwise followed by the bromoacetylene 2 (116 mg, 0.352 mmol). The mixture was allowed to stir overnight at room temperature. Water was added and the suspension was
extracted using heptane, washed with brine, dried (MgSO4) and concentrated. Purification using flash column chromatography (10% EtOAc in heptane) yielded 5 (100 mg, 81%) as a colorless oil. 5: IR ν 3355, 2929, 2852, 2359, 2337, 1749, 1717, 1498, 1447, 1365, 1251, 1181, 1060; 1H NMR (300 MHz, CDCl3) δ 5.28 (d, J = 7.7 Hz, 1H), 4.43–4.38 (m, 1H), 3.73 (s, 3H), 2.69–2.63 (m, 2H), 2.13 (m, 1H), 1.73–1.22 (m, 10H), 1.43 (s, 9H); 13C NMR (75 MHz, CDCl3) δ 171.4, 155.0, 88.1, 79.9, 73.8, 52.3, 32.7, 32.7, 28.8, 28.2, 25.8, 24.6, 23.1; HRMS (EI): calculated for C17H27NO4 309.1940, found 309.1937.
A solution of the tungsten catalyst (7 mg, 10 mol%) in C6H5Cl (2 mL) was treated with a solution of 14 (49.0 mg, 0.120 mmol) in C6H5Cl (5.0 mL) under an argon atmosphere and the resulting mixture was heated at 80°C for 3 h. Evaporation followed by flash
column chromatography (80% EtOAc in heptane) afforded 15 (21.0 mg, 50%; 64% after correction for starting material) and 14 (16 mg, 33%) as colorless oils. 15: [α]D =–14.6 (c = 1, CH2Cl2); IR ν 3313, 2931, 2865, 2249, 1744, 1667, 1520, 1366, 1170; 1H NMR (400 MHz, CDCl3) δ 7.14 (d, J = 8.7 Hz, 1H), 6.08 (d, J = 8.3 Hz, 1H), 4.78 (q, J = 6.8 Hz, 1H), 4.27 (q, J = 7.9 Hz, 1H), 3.73 (s, 3H), 2.17–2.15 (m, 4H), 2.07–1.96 (m, 2H), 1.79–1.52 (m, 4H), 1.45 (s, 9H), 0.89–0.83 (m, 2H); 13C NMR (100 MHz, CDCl3) δ 173.2, 171.8, 155.8, 80.4, 80.2, 79.3, 53.8, 52.5, 51.2, 32.8 (2×), 28.1, 24.6, 24.2, 18.3 (2×); HRMS (EI): calculated for
C18H28N2O5 相似文献
140.
A. Yu. Tsibulevsky T. K. Dubovaya A. I. Shchegolev A. I. Sergeev A. V. Bykov Kh. K. Gadzhieva 《Biology Bulletin》2005,32(6):590-596
Intoxication with bacterial lipopolysaccharide (endotoxin) is accompanied by considerable rearrangements in the systems of blood microcirculation and water metabolism of the liver. These rearrangements are manifested as increased sinusoid area, changed total area of the cytoplasm and nuclei as well as the nucleocytoplasmic ratio in hepatocytes, increased content of total water in the organ, and changed magnetic relaxation properties (spin-lattice and spin-spin relaxation times). Preliminary parasympathetic denervation of the liver (vagotomy) changes the pattern of the organ response to bacterial endotoxin poisoning as indicated by the kinetics of studied morphological and biophysical parameters. 相似文献