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51.
52.
A Simulation of Temporal and Spatial Variations in Carbon at Landscape Level: A Case Study for Lake Abitibi Model Forest in Ontario,Canada 总被引:2,自引:0,他引:2
Xiaolu Zhou Changhui Peng Qing-Lai Dang Jiaxin Chen Sue Parton 《Mitigation and Adaptation Strategies for Global Change》2007,12(4):525-543
Using a case study of the Lake Abitibi Model Forest (LAMF), this study aims to assess the temporal and spatial variability
in carbon storage during 1990–2000, and to present a comprehensive estimation of the carbon budget for LAMF's ecosystems.
As well, it provided the information needed by local forest managers to develop ecological and carbon-based indicators and
monitor the sustainability of forest ecosystems. Temporal and spatial carbon dynamics were simulated at the landscape level
using ecosystem model TRIPLEX1.0 and Geographical Information System (GIS). The simulated net primary productivity (NPP) and
carbon storage in forest biomass and soil were compared with field data and results from other studies for Canada's boreal
forests. The results show that simulated NPP ranged from 3.26 to 3.34 tC ha−1 yr−1 in the 1990s and was consistent with the range measured during the Boreal Ecosystem-Atmosphere Studies (BOREAS) in central
Canada. Modeled NPP was also compared with the estimation from remote sensing data. The density of total above-and belowground
biomass was 125.3, 111.8, and 106.5 tC ha−1 for black spruce, trembling aspen, and jack pine in the LAMF ecosystem, respectively. The total carbon density of forested
land was estimated at 154.4 tC ha−1 with the proportion of 4:6 for total biomass and soil. The analysis of net carbon balance of ecosystem suggested that the
LAMF forest ecosystem was acting as a carbon sink with an allowable harvest in the 1990s. 相似文献
53.
In angiosperms, archesporial cells in the anther primordium undergo meiosis to form haploid pollen, the sole occupants of anther sacs. Anther sacs are held together by a matrix of parenchyma cells, the connective tissue. Cells of the connective tissue are not known to differentiate. We report the differentiation of parenchyma cells in the connective tissue of two Gordonia species into pollen-like structures (described as pseudopollen), which migrate into the anther sacs before dehiscence. Pollen and pseudopollen were distinguishable by morphology and staining. Pollen were tricolpate to spherical while pseudopollen were less rigid and transparent with a ribbed surface. Both types were different in size, shape, staining and surface architecture. The ratio of the number of pseudopollen to pollen was 1:3. During ontogeny in the connective tissue, neither cell division nor tetrad formation was observed and hence pseudopollen were presumed to be diploid. Only normal pollen germinated on a germination medium. Fixed preparations in time seemed to indicate that pseudopollen migrate from the connective tissue into the anther sac. 相似文献
54.
55.
John S. Rinehart 《Die Naturwissenschaften》1976,63(5):218-223
56.
Axel Michaelowa John O’brien 《Mitigation and Adaptation Strategies for Global Change》2006,11(3):711-722
A United Nations Framework Convention on Climate Change (UNFCCC) Joint Implementation (JI) host country has to make sure that
JI projects are additional to avoid extra costs to generate the reductions necessary to cover the deduction of Emission Reduction
Units (ERUs) from the country’s Kyoto Protocol emissions budget. A tender of ERUs by the government allows to generate additional
reductions beyond the ERUs issued if it thoroughly checks project additionality. The government of New Zealand is running
a tender for JI projects under the title “Projects to Reduce Emissions” since 2003. In two rounds, 10 million ERUs have been
awarded and several projects have already entered into contracts with European buyers. The ratio of ERUs awarded to reductions
achieved was 0.8 in the second tender. However it remains to be seen whether the additionality test of this tender is sufficient
to exclude clearly non-additional projects. 相似文献
57.
Steen Smidt-Jensen Claes Lundsteen Anne-Marie Lind Kirsten Dinesen John Philip 《黑龙江环境通报》1993,13(10):957-969
Transabdominal chorionic villus sampling (TA-CVS) was performed in 210 pregnancies from 13 to 38 weeks using a double-needle technique. The sampling success was comparable to first-trimester TA-CVS and the diagnostic success rate was 98.2 per cent for the short-term technique and 99.3 per cent for cultured villi. Two fetuses could not be karyotyped. We found the chromosome quality to be similar to that in the first trimester, comparing the number of G-bands and other chromosome attributes. There were no unintended losses in a group (n = 142) with no sonographic abnormality, except for one death in utero at 38 weeks, 20 weeks after sampling. Chromosomal aberrations were seen in 19 per cent of cases with abnormal sonograms (n = 58). One case of a discordant karyotype was found (false-negative prediction of Down's syndrome by the short-term preparation). There were no cases of fetal demise due to feto-maternal bleeding. It is suggested that double-needle TA-CVS in advanced pregnancies combines the advantages of rapid karyotyping of chromosomes of good quality and low risk for the fetus, and seems to be easier to practise and is probably safer than cordocentesis. 相似文献
58.
Siegfried Rotmensch Marco Liberati Jia-Sen Luo Giovanni Tallin Maurice J. Mahoney John C. Hobbins 《黑龙江环境通报》1991,11(11):867-873
Many authors have suggested that individuals affected by a terminal 1q deletion display a phenotypically definable and recognizable syndrome. In all of the 27 cases reported to date, the breakpoints were at band q42 or distally to it. To our knowledge, we report the first case of a terminal 1q41 deletion. Diagnosis was made prenatally by amniocentesis, following ultrasonographic diagnosis of omphalocele, cerebral ventriculomegaly, and increased nuchal fold thickness in a 19-week female fetus. Multiple facial and extremity features were consistent with the proposed distal 1q deletion syndrome; omphalocele, however, has not been reported previously. The absence of liver herniation into the omphalocele sac in this case supports the previously reported association of this finding with chromosomal anomalies. 相似文献
59.
Aris Antsaklis John Politis Costas Karagiannopoulos Dionysios Kaskarelis Photini Karababa John Panourgias Marina Boussiou Dimitris Loukopoulos 《黑龙江环境通报》1984,4(4):289-296
Selective feticide is the procedure of choice when, in twin binovular pregnancy, only one of the fetuses is shown to be affected. As the probabilities for this condition are almost 1:2 when the genetic disease is due to homozygosity for two autosomal recessive genes, the problem is expected to occur frequently among the ever increasing number of couples seeking prenatal diagnosis of thalassaemia and the haemoglobinopathies. The present report is the first case of this condition and the ninth in the overall medical literature. 相似文献
60.
Diana W. Bianchi MD Gretchen K. Zickwolf Melissa C. Yih Alan F. Flint Ossie H. Geifman Marlena S. Erikson John M. Williams 《黑龙江环境通报》1993,13(4):293-300
Fetal nucleated erythrocytes (NRBC) in maternal blood are a non-invasive source of fetal DNA for prenatal genetic screening. We compared the effectiveness of three monoclonal antibodies for the separation of fetal cells from maternal blood by flow sorting. Mononuclear blood cells from 49 healthy pregnant women were incubated with antibody to CD 71, CD 36, and/or glycophorin A (GPA), employed singly or in combination with each other. These monoclonal antibodies recognize surface antigens on haematopoietic precursor cells. Successful isolation of fetal cells was defined as detection of Y chromosomal sequences in maternal blood from women carrying male fetuses, with absence of Y sequences when female fetuses were carried. Thus, gender prediction accuracy was used as a measure of fetal cell separation. Using anti-CD 71 to isolate fetal cells, gender prediction was 57 per cent correct; with anti-CD 36, it was 88 per cent correct. Anti-GPA, an erythrocyte-specific antigen, used alone or in combination with anti-CD 71 or 36, improved gender prediction to 100 per cent. We conclude that antibody to GPA improves the retrieval of fetal NRBC from maternal blood, permitting genetic analysis by the polymerase chain reaction. 相似文献