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21.
Masera Omar R. Cerón Alma Delia Ordóñez Antonio 《Mitigation and Adaptation Strategies for Global Change》2001,6(3-4):291-312
We examine carbon (C) reference and mitigation scenarios for the Mexicanforest sector between the year 2000 and 2030. Estimates are presentedseparately for the period 2008–2012.Future C emissions and capture are estimated using a simulation modelthat: a) allocates the country land use/land cover classes among differentfuture uses and categories using demand-based scenarios for forestryproducts; b) estimates the total C densities associated to each land usecategory, and c) determines the net carbon implications of the process ofland use/cover change according to the different scenarios.The options analyzed include both afforestation/reforestation, such ascommercial, bionenergy and restoration plantations, and agroforestrysystems, and forest conservation, through the sustainable management ofnative forests and forest protection.The total mitigation potential, estimated as the difference between the totallong-term carbon stock in the reference and the mitigation scenario reaches300 × 106 Mg C in the year 2012 and increases to 1,382 × 106 Mg C in 2030. The average net sequestration in the 30 year period is 46 × 106 Mg C yr-1, or 12.5 × 106 Mg C yr-1 within the period 2008 to 2012. The costs of selected mitigation options range from 0.7–3.5 Mg C-1 to 35 Mg C-1. Some options are cost effective. 相似文献
22.
Dr. E. Gratacós P. J. Torres J. Vidal J. Font E. Antolin V. Cararach A. Fortuny 《黑龙江环境通报》1995,15(12):1109-1113
Anticardiolipin antibodies were measured in 60 pregnant women with acute parvovirus B19 infection. Test results for eight (13.3 per cent) women were positive for anticardiolipin antibody. Six of these eight women became negative later, yielding a prevalence of anticardiolipin antibodies of 3.3 per cent (2/60) 6 months after acute parvovirus B19 infection. Anticardiolipin antibody positivity was not associated with an increased risk of abortion, fetal death, or maternal complications. This study suggests that there is an elevated frequency of anticardiolipin antibodies in pregnant women with acute parvovirus B19, probably representing an epiphenomenon. However, this is not associated with an adverse maternal or perinatal outcome. 相似文献
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24.
过去50年中国森林资源和降水变化的统计分析 总被引:8,自引:0,他引:8
论文对过去50年中国森林资源和降水变化进行了统计分析,以期在大尺度上寻找森林资源与降水变化之间的关系。主要结论为:①建国以来我国的森林覆盖率呈上升趋势;②过去50年全国、林区、非林区降水量均呈减少趋势,干旱化趋势明显;③对建国后历次森林资源调查(清查)时段内降水差值(以百分数为单位)、森林覆盖率(以相邻两次变化百分数为单位)变化关系的分析表明,二者的统计关系并不显著,即:过去50年我国森林资源的变化对降水没有显著的影响;④森林影响降水是一个复杂的系统问题,该研究还存在着许多不确定性因素,需进一步实验验证与理论探讨。 相似文献
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The Science of Nature - 相似文献
27.
Dr J. L. Carrasco Juan A. Otero Gómez M. C. Vilar Mesa J. L. García Miranda J. M. Troyano Luque O. Morales Ruiz J. Parache Hernández 《黑龙江环境通报》1989,9(6):443-445
A dicentric X chromosome was found in a female fetus during cytogenetic studies performed on amniotic cells. Blood samples from the parents showed normal karyotypes and the pregnancy was terminated. The mechanism for the formation of this ‘de novo’ rearrangement is discussed. 相似文献
28.
D. Costa A. Borrell E. Margarit A. Carrió A. Soler I. Balmes X. Estivill A. Fortuny 《黑龙江环境通报》1995,15(2):141-148
Fluid from pleural effusion (n=2) and cystic hygroma (n=7) was obtained from eight fetuses, between 13 and 32 weeks of pregnancy at the time when a conventional prenatal diagnosis procedure was carried out. As these fluids contain lymphocytes, they were processed like peripheral blood. A karyotype was obtained in 4 days in both cases of pleural effusion and in four out of seven samples of cystic hygroma. An abnormal karyotype was detected in three of the four samples of cystic hygroma: two trisomies 21 and a monosomy X. Different parameters were evaluated in order to predict the feasibility of obtaining a cytogenetic diagnosis. Our data showed that if the amount of fluid obtained was ⩾4 ml and the initial lymphocyte count (ILC) was >0.2 × 106 cells/ml, a cytogenetic diagnosis was possible from an initial concentration of cultured lymphocytes )ICCL) of >0.06 × 106 cells/ml. 相似文献
29.
Kevin Summers Leroy Folmar Miriam Rodón-Naveira 《Environmental monitoring and assessment》1997,47(3):275-301
As part of the Environmental Monitoring and Assessment Programin 1991, the field efficacy of six research indicators wasexamined in the estuarine systems of the Gulf of Mexico. Theutility of these indicators was tested by examining thoseresponses at both ends of multiple environmental gradients;namely, under minimally impacted conditions (reference) andheavily impacted conditions (by hypoxia, industrialdischarges, agricultural runoff). In addition, the geographiceffects of location (east and west of the Mississippi River)were examined. Numbers and frequencies of pathologies,abundance of splenic macrophage aggregates, and vertebralabnormalities showed response patterns that suggest widerfield testing along full gradients rather than simply theextremes of the gradient are warranted. Selected bloodproteins showed some promise but logistical constraints inestuarine environments may limit its utility. Concentrationsof selected organic compounds in bile showed no differences inthis study between references and contaminated sites.Molecular bioindicators are discussed with regard to theirpotential utility as indicators of ecosystem conditions. Ofthese potential indicators, the use of vitellogenin assays asa measure of reproductive impairment and frequency of shelldisease in selected crustaceans as an indicator ofimmunological aberrations deserve further examination. 相似文献
30.
The presence and characteristics of a membrane-bound adenylate cyclase from Mytilus galloprovincialis Lmk posterior adductor muscle have been investigated. The enzyme has a Michaelis constant (K
m) of 0.38 mM at 20°C and requires divalent cations (Mg2+/Mn2+) for its activity. Optimal GTP concentrations are between 10-5 and 10-4
M. The non-hydrolizable GTP-analogues GMPpNHp and GTPS increase the activity of the enzyme four- to ten-fold. Sodium fluoride stimulates the enzymatic activity seven- to eight-fold. Forskolin increases the enzymatic activity two- to three-fold. Serotonin stimulates the adenylate cyclase activity in a dose-dependent manner. These experiments were performed with mussels collected from the estuary of Muros, Spain, in 1990. 相似文献