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排序方式: 共有518条查询结果,搜索用时 15 毫秒
511.
Rivera MN Kim WJ Wells J Driscoll DR Brannigan BW Han M Kim JC Feinberg AP Gerald WL Vargas SO Chin L Iafrate AJ Bell DW Haber DA 《Science (New York, N.Y.)》2007,315(5812):642-645
Wilms tumor is a pediatric kidney cancer associated with inactivation of the WT1 tumor-suppressor gene in 5 to 10% of cases. Using a high-resolution screen for DNA copy-number alterations in Wilms tumor, we identified somatic deletions targeting a previously uncharacterized gene on the X chromosome. This gene, which we call WTX, is inactivated in approximately one-third of Wilms tumors (15 of 51 tumors). Tumors with mutations in WTX lack WT1 mutations, and both genes share a restricted temporal and spatial expression pattern in normal renal precursors. In contrast to biallelic inactivation of autosomal tumor-suppressor genes, WTX is inactivated by a monoallelic "single-hit" event targeting the single X chromosome in tumors from males and the active X chromosome in tumors from females. 相似文献
512.
Fragrant screwpine fiber reinforced unsaturated polyester composites (FSFRUPC) were subjected to water immersion tests in order to examine the effect of water absorption on the mechanical properties. FSFRUP composite specimen containing 30 % fiber volume fraction with fiber length of 3 mm and 9 mm was considered in this study. Water absorption test was performed by immersing specimen in sea, distilled and well water at room temperature under different time durations (24, 48, 72, 96, 120, 144, 168, 192, 216, 240 hours). The tensile, flexural and impact properties of the water absorption specimen were appraised and compared with those of the dry composite specimen as per the ASTM standard. The tensile, flexural and impact properties of FSFRUPC specimen were found to decrease with the increase in the percentage of moisture uptake. The percentage of moisture uptake of composite was reduced after alkali treatment with 3 % NaoH for 3 hours. In moisture absorption test, the lowest diffusion coefficient, D (6.62513×10-13 m2/s) and swelling rate parameter, K sr (6.341×10-3 h-1) were obtained through the specimen immersed in sea water. The chemical composition, elemental composition of fiber and surface morphology of the FSFRUPC were analysed by using Fourier transform infrared spectroscopy (FTIR), Energy dispersive spectroscopy (EDS) and scanning electron microscopy (SEM) respectively. 相似文献
513.
Späth GF Lye LF Segawa H Sacks DL Turco SJ Beverley SM 《Science (New York, N.Y.)》2003,301(5637):1241-1243
Leishmania infections involve an acute phase of replication within macrophages, typically associated with pathology. After recovery parasites persist for long periods, which can lead to severe disease upon reactivation. Unlike the role of host factors, parasite factors affecting persistence are poorly understood. Leishmania major lacking phosphoglycans (lpg2-) were unable to survive in sand flies and macrophages, but retained the ability to persist indefinitely in the mammalian host without inducing disease. The L. major lpg2- thus provides a platform for probing parasite factors implicated in persistence and its role in disease and immunity. 相似文献
514.
Cyanobacterial toxins as allelochemicals with potential applications as algaecides, herbicides and insecticides 下载免费PDF全文
Cyanobacteria (“blue-green algae”) from marine and freshwater habitats are known to produce a diverse array of toxic or otherwise bioactive metabolites. However, the functional role of the vast majority of these compounds, particularly in terms of the physiology and ecology of the cyanobacteria that produce them, remains largely unknown. A limited number of studies have suggested that some of the compounds may have ecological roles as allelochemicals, specifically including compounds that may inhibit competing sympatric macrophytes, algae and microbes. These allelochemicals may also play a role in defense against potential predators and grazers, particularly aquatic invertebrates and their larvae. This review will discuss the existing evidence for the allelochemical roles of cyanobacterial toxins, as well as the potential for development and application of these compounds as algaecides, herbicides and insecticides, and specifically present relevant results from investigations into toxins of cyanobacteria from the Florida Everglades and associated waterways. 相似文献
515.
Michael Heym Ricardo Ruíz-Peinado Miren Del Río Kamil Bielak David I. Forrester Gerald Dirnberger Ignacio Barbeito Gediminas Brazaitis Indrė Ruškytkė Lluís Coll Marek Fabrika Lars Drössler Magnus Löf Hubert Sterba Václav Hurt Viktor Kurylyak Fabio Lombardi Dejan Stojanović Jan Den Ouden Renzo Motta Maciej Pach Jerzy Skrzyszewski Quentin Ponette Géraud De Streel Vit Sramek Tomáš Čihák Tzvetan M. Zlatanov Admir Avdagic Christian Ammer Kris Verheyen Buraczyk Włodzimierz Andrés Bravo-Oviedo Hans Pretzsch 《Annals of Forest Science》2017,74(3):63
Key message
This data set provides unique empirical data from triplets of Scots pine ( Pinus sylvestris L.) and European beech ( Fagus sylvatica L.) across Europe. Dendrometric variables are provided for 32 triplets, 96 plots, 7555 trees and 4695 core samples. These data contribute to our understanding of mixed stand dynamics. Dataset access at http://dx.doi.org/10.5061/dryad.8v04m . Associated metadata available at https://metadata-afs.nancy.inra.fr/geonetwork/apps/georchestra/?uuid=b3e098ca-e681-4910-9099-0e25d3b4cd52&hl=eng .516.
Lin J Gunter LE Harding SA Kopp RF McCord RP Tsai CJ Tuskan GA Smart LB 《Tree physiology》2007,27(11):1575-1583
Salix matsudana Koidz. cultivar 'Tortuosa' (corkscrew willow) is characterized by extensive stem bending and curling of leaves. To investigate the genetic basis of this trait, controlled crosses were made between a corkscrew female (S. matsudana 'Tortuosa') and a straight-stemmed, wild-type male (Salix alba L. Clone 99010). Seventy-seven seedlings from this family (ID 99270) were grown in the field for phenotypic observation. Among the progeny, 39 had straight stems and leaves and 38 had bent stems and curled leaves, suggesting that a dominant allele at a single locus controls this phenotype. As a first step in characterizing the locus, we searched for amplified fragment length polymorphism (AFLP) and randomly amplified polymorphic DNA (RAPD) markers linked to the tortuosa allele using bulked segregant analysis. Samples of DNA from 10 corkscrew individuals were combined to produce a corkscrew pool, and DNA from 10 straight progeny was combined to make a wild-type pool. Sixty-four AFLP primer combinations and 640 RAPD primers were screened to identify marker bands amplified from the corkscrew parent and progeny pool, but not from the wild-type parent or progeny pool. An AFLP marker and a RAPD marker linked to and flanking the tortuosa locus were placed on a preliminary linkage map constructed based on segregation among the 77 progeny. Sectioning and analysis of shoot tips revealed that the corkscrew phenotype is associated with vascular cell collapse, smaller cell size in regions near the cambium and less developed phloem fibers than in wild-type progeny. Identification of a gene associated with this trait could lead to greater understanding of the control of normal stem development in woody plants. 相似文献
517.
Adya P. Singh Uwe Schmitt Ralf Möller Bernard S.W. Dawson Gerald Koch 《Wood Science and Technology》2006,40(1):16-25
A visual decay assessment of Pinus radiata wood, which was part of a framing timber in a house in the North Island of New Zealand, indicated the presence of surface
decay. Microscopic observations, employing confocal laser scanning microscopy (CLSM), scanning electron microscopy (SEM) and
transmission electron microscopy (TEM), provided evidence of decay by cavity-forming soft rot (SR) fungi. A comparison of
ray tracheids (RT) with axial tracheids (AT) indicated that RT were considerably more resistant to SR than AT. In the heavily
degraded regions of wood, where axial tracheid walls contained abundant SR cavities, the walls of RT contained only a few
or no cavities. An assessment of lignin concentration in the cell walls by a combination of TEM, confocal fluorescence and
UV microscopy provided evidence of greater lignin concentration in the secondary wall of RT as compared to AT, which may explain
the observed greater resistance of RT to soft rot.
Dedicated to Professor Dr. Dr. h.c. mult. Walter Liese on the occasion of his 80th birthday. 相似文献
518.
Nguyen-Van-Hung Balingbing Carlito Sandro Joseph Khandai Suryakanta Chea Hong Songmethakrit Thanach Meas Pyseth Hitzler Gerald Zwick Walter Viriyangkura Ladda Bautista Elmer Gummert Martin 《Precision Agriculture》2022,23(5):1633-1652
Precision Agriculture - Laser-controlled land leveling (LLL) can help improve rice production's spatial and temporal management, leading to optimized water and crop management. This research... 相似文献