首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 31 毫秒
1.
天河公园生态系统服务功能价值的初步研究   总被引:2,自引:0,他引:2  
应用市场价值法、影子工程法、生产成本法和替代花费法等对天河公园生态系统服务功能价值进行评估。结果表明,天河公园生态系统服务的年总价值为140486.6万元,其中房地产升值价值134956.0万元,休闲游憩价值5000.0万元,生产有机物价值43.5万元,涵养水源与净化水质价值287.5万元,土壤保护价值24.4万元,维持二氧化碳和氧气平衡价值110.4万元,调节小气候价值16.5万元,净化空气价值20.8万元,卫生保健价值27.5万元。  相似文献   

2.
Cimini V 《Peptides》2000,21(11):1711-1716
Immunocytochemical analysis of endocrine cells of the developing rat pituitary has shown clearly that, starting from E16, the galanin-immunoreactive cells are heterogeneous, the neuropeptide being present in cells containing the majority of pituitary hormones. A proportion of galanin-containing corticotropes, starting from about 17% at E16 reached about 29% at E21, while the galanin-containing lactotrope increase in the same period was from about 13% to 34%. Galanin-containing thyrotropes ranged from about 11% at E16 to about 13% at E21, while the proportion of galanin-containing luteotropes increased consistently from about 17% at E19 to about 27% at E21. Only the trend of galanin-containing somatotropes was inverted, falling from about 26% to 13%. We conclude that the multiple coexistence of galanin with most of the pituitary hormones during fetal development is a further example of plasticity of endocrine pituitary cells, and that galanin may have a role in cytodifferentiation.  相似文献   

3.
白云山森林生态系统间接经济价值评估   总被引:30,自引:2,他引:30  
使用市场价值法,影子工程法,机会成本法和替代法等对白云山1800hm2森林生态系统的功能价值进行经济评估,评估结果表明,白云山总的生态价值为14 580.17万元,其中活立木生产量的价值1423.58万元,涵养水源价值和保护土壤价值为460.66万元,固定二氧化碳和放出氧气的价值为3623.54万元,动物栖息地和生物多样性保护价值为632.47万元,林分持留N、P、K养分价值133.52万元,卫生保健价值为1737万元,农业粮食产量增加价值为2 338.54万元,降解SO2和防治病虫害17.33万元,旅游价值4 213.53万元。  相似文献   

4.
中国红树林生态系统生态价值评估   总被引:69,自引:0,他引:69  
使用市场价值法 ,影子工程法 ,机会成本法和替代花费法等对中国现存自然分布的136 4 6hm2 的红树林生态系统的功能价值进行经济评估 ,评估结果表明 ,中国红树林总的年生态功能价值为 2 36 531万元 ,其中生物量价值 816 3万元 ,抗风消浪护岸价值 992 0 6万元 ,保护土壤价值 1156 92万元 ,固碳以减弱温室效应和释放O2 的价值 6 70 6万元 ,生物多样性保护即动物栖地价值 5470万元 ,林分养分积累价值 10 12万元 ,污染物生物降解和病虫害 2 82万元。  相似文献   

5.
A fundamental lack of data on the potential impacts of carbon based nanomaterials on natural ecosystems currently exists. The gap between what we know about environmental impacts and new products that may contain nanomaterials continues to get wider especially related to knowledge about nanocomposites. In this paper we present ideas and concerns about the current state of knowledge on nanomaterials in the environment and present a number of points about what recent work has provided us about the novel materials.  相似文献   

6.
1. Under normal circulation of the dog submandibular gland, the electrical stimulation induced a massive salivary secretion (about 0.35 ml . min-1.g-1 gland weight) and an increase in the glandular temperature (about 0.2 degrees C). The heat production was calculated of about 60 mW.g-1. 2. Clamping of the glandular artery made both of secretion and heat production to be transient. The early peak of secretion was about 0.12 ml.min-1.g and that of heat production was 7 approximately 10mW,g-1. Then each 1 ml secretion followed about 4.6 J heat production. 3. Under constant blood flow in the glandular circulation, the secretory process was divided clearly into 2 phases of peak and plateau. The glandular temperature increased about 0.12 degrees C with an early temperature drop. In the secretory plateau phase, the secretary rate was about 0.043 ml.min-1.g-1, the heat production was about 5 approximately 7 mW.g-1 and each 1 ml secretion caused about 8.2 J heat production. 4. The rate of oxygen uptake was about 20.9 microl.min-1g-1 at the resting state. The maximum during secretion was about 192 microliter.min-1.g-1. THe half time of the recovery process of O2 uptake tended slightly longer than that of heat production. 5. THe rate of CO2 output was about 21.8 microliter.min-1.g-1 at resting. The maximum during secretion was about 142 microliter.min-1.g-1 R. Q. were about 1 at resting and about 0.74 under secretion.  相似文献   

7.
以尖峰岭地区为研究区域,探讨了森林生态系统服务功能的内涵,并使用市场价值,影子工程、机会成本和替代花费等方法评价了海南岛尖峰岭地区热带森林生态系统服务功能的生态经济价值,结果表明,在尖峰岭地区,面积为44667.00hm^2的热带森林生态系统服务功能价平均每年6638.49万元,其中林产品价值为7164.11万元,涵养水源价值为39429.21万元,保持土壤减少侵蚀价值为247.26万元,固定CO  相似文献   

8.
Farming is the basis of our civilization yet is more damaging to wild nature than any other sector of human activity. Here, we propose that in order to limit its impact into the future, conservation researchers and practitioners need to address several big topics--about the scale of future demand, about which crops and livestock to study, about whether low-yield or high-yield farming has the potential to be least harmful to nature, about the environmental performance of new and existing farming methods, and about the measures needed to enable promising approaches and techniques to deliver on their potential. Tackling these issues requires conservationists to explore the many consequences that decisions about agriculture have beyond the farm, to think broadly and imaginatively about the scale and scope of what is required to halt biodiversity loss, and to be brave enough to test and when necessary support counterintuitive measures.  相似文献   

9.
以尖峰岭地区为研究区域,探讨了森林生态系统服务功能的内涵,并使用市场价值、影子工程、机会成本和替代花费等方法评价了海南岛尖峰岭地区热带森林生态系统服务功能的生态经济价值.结果表明,在尖峰岭地区,面积为44667.00hm2的热带森林生态系统服务功能价值平均每年66438.49万元,其中林产品价值为7164.11万元,涵养水源价值为39429.21万元,保持土壤减少侵蚀价值为247.26万元,固定CO2减轻温室效应的价值为1316.24万元,营养物循环价值为428.55万元,净化空气的价值为17853.12万元.  相似文献   

10.
以尖峰岭地区为研究区域,探讨了森林生态系统服务功能的内涵,并使用市场价值、影子工程、机会成本和替代花费等方法评价了海南岛尖峰岭地区热带森林生态系统服务功能的生态经济价值.结果表明,在尖峰岭地区,面积为44667.00hm2的热带森林生态系统服务功能价值平均每年66438.49万元,其中林产品价值为7164.11万元,涵养水源价值为39429.21万元,保持土壤减少侵蚀价值为247.26万元,固定CO2减轻温室效应的价值为1316.24万元,营养物循环价值为428.55万元,净化空气的价值为17853.12万元.  相似文献   

11.
Ethical issues in human genome research.   总被引:2,自引:0,他引:2  
In addition to provocative questions about science policy, research on the human genome will generate important ethical questions in at least three categories. First, the possibility of greatly increased genetic information about individuals and populations will require choices to be made about what that information should be and about who should control the generation and dissemination of genetic information. Presymptomatic testing, carrier screening, workplace genetic screening, and testing by insurance companies pose significant ethical problems. Second, the burgeoning ability to manipulate human genotypes and phenotypes raises a number of important ethical questions. Third, increasing knowledge about genetic contributions to ethically and politically significant traits and behaviors will challenge our self-understanding and social institutions.  相似文献   

12.
The rate of attachment of chick embryo fibroblasts (CEF) incubated for 1 h at pH 6 in the absence of serum, was equal to about 90% with 2% of spreading cells. The addition of 1% horse serum (HS) decreased to about 30% the rate of attached cells but increased to about 30% the proportion of spreading cells. We found that 3 microM cobalt-protoporphyrin IX (CoPP) added for 3 min before the addition of 1% HS increased both the rate of cell attachment (about 60%) and the proportion of cell spreading (about 50%).  相似文献   

13.
The mRNA coding for epsilon-heavy chain and kappa-light chain have been highly enriched from a rat IgE-producing myeloma, IR-162. Based on denaturing gel analyses, the 20 S epsilon-heavy chain mRNA has an estimated molecular weight of 850,000, equivalent to about 2500 nucleotides. The 14S rat kappa-light chain mRNA has an estimated molecular weight of 410,000, equivalent to about 1200 nucleotides. Only about two-thirds of the length of these mature cytoplasmic rat mRNA code for protein. The 20 S mRNA stimulates the in vitro synthesis of a single major serologically related protein which is large enough to be epsilon-heavy chain. It is unglycosylated and has an apparent molecular weight of about 62,000. The in vivo unglycosylated epsilon-heavy chain, obtained in the presence of tunicamycin, has an apparent molecular weight of about 59,000, compared with about 76,000 for the glycosylated heavy chain of the secreted rat IgE. Therefore, the in vitro synthesized epsilon-heavy chain protein is about Mr = 3000 larger than the in vivo unglycosylated epsilon-heavy chain, equivalent to about 25 extra amino acids. This is consistent with the synthesis of an epsilon-heavy chain putative precursor. Likewise, the 14 S mRNA stimulates the in vitro synthesis of a single putative precursor protein, which is serologically related to kappa chain, is unglycosylated, and is about an extra 20 amino acids. This is the first report on the physical and biological properties of an epsilon-heavy chain mRNA, as well as any rat immunoglobulin mRNA.  相似文献   

14.
Genes and patent policy: rethinking intellectual property rights   总被引:1,自引:0,他引:1  
Concerns about human gene patents go beyond moral disquiet about creating a commodity from a part of the human body and also beyond legal questions about whether genes are unpatentable products of nature. New concerns are being raised about harm to public health and to research. In response to these concerns, various policy options, such as litigation, legislation, patent pools and compulsory licensing, are being explored to ensure that gene patents do not impede the practice of medicine and scientific progress.  相似文献   

15.
庄永龙  周敏  李衍达  沈岩 《遗传》2004,26(4):514-518
随着人类基因组序列草图的完成,基因组突变的研究显得日益重要,而越来越多的突变信息的积累,使得各种突变数据库相继诞生。本文根据各种数据库的功能,对目前的人类突变相关数据库资源进行了分类总结,分类为突变数据库、单核苷酸多态信息数据库、与疾病相关的突变数据库、突变对蛋白质的影响、突变图谱以及特定基因的突变信息,分析该如何合理使用这些遗传突变数据资源,以及目前的突变数据库所存在的问题。Abstract:Researches on genome mutation are becoming more and more important with the finish of human genome DNA draft. This review is to classify the existing human mutation databases, including mutation database, SNP(single nucleotide polymorphisms) databases, mutation databases about disease, mutation databases about proteins, mutation databases about map and mutation information about specific gene. We also give advice on how to utilize these mutation databases, and discuss problems of existing databases.  相似文献   

16.
Between 3 weeks and 36 months after irradiation of mice, there was a dose-dependent increased level of cycling in haemopoietic stem cells (CFU-S) and in granulocyte-macrophage precursor cells (GM-CFC). For CFU-S the percentage kill measured using the thymidine suicide technique increased from about 10% in controls to a high and persistent average level of about 45% after 10 Gy gamma-rays, and for GM-CFC the increase was from about 30% to about 50%.  相似文献   

17.
The aim of this study was to explore the prevalence, nature and determinants of concerns about mobile phone radiation. We used data from a 2006 telephone survey of 1004 people aged 15+ years in Denmark. Twenty‐eight percent of the respondents were concerned about exposure to mobile phone radiation; radiation from masts was of concern to about 15%. In contrast, 82% were concerned about pollution. Nearly half of the respondents considered the mortality risk of 3G phones and masts to be of the same order of magnitude as being struck by lightning (0.1 fatalities per million people per year) while 7% thought it was equivalent to tobacco‐induced lung cancer (~500 fatalities per million per year). Among women, concerns about mobile phone radiation were positively associated with educational attainment, perceived mobile phone mortality risk and concerns about unknown consequences of new technologies. More than two thirds of the respondents felt that they had received inadequate public information about the 3G system. The results of the study indicate that the majority of the population has little concern about mobile phone radiation while a small minority is very concerned. Bioelectromagnetics 30:393–401, 2009. © 2009 Wiley‐Liss, Inc.  相似文献   

18.
Uganda is invoked as a metaphor for a host of arguments and insights about HIV/AIDS. However, much of what has been asserted about the country is not based on the available evidence. This paper reviews findings by epidemiologists and anthropologists, and draws on the author's experiences of researching in the country since the early 1980s. It comments on various myths about HIV/AIDS in Uganda, including myths about the origin and dissemination of the disease, about the links between HIV/AIDS and war, and about declining rates of infection. It shows that much less is known about Uganda than is commonly supposed, and it offers some alternative hypotheses for interpreting HIV prevalence and incidence data. In particular it draws attention to the importance of mechanisms for social compliance. It concludes by raising concerns about the current enthusiasm for provision of anti-retroviral drugs.  相似文献   

19.
Summary The period between oviposition and the start of hatching varied from about 17 weeks at 3°C to about 1 week at 22°C, and the length of the hatching period varied from about 34 days at 3°C to about 3 days at 22°C. Regression equations are provided to estimate the lengths of both periods at all temperatures between 3°C and 22°C.  相似文献   

20.
Microvilli on sea urchin eggs: a second burst of elongation   总被引:6,自引:0,他引:6  
A scanning EM study reveals about 300,000 microvilli on each egg of the sea urchin Strongylocentrotus droebachiensis. The microvilli are about 0.2 μm long before fertilization, elongate to about 0.5 μm soon after fertilization (the “first burst” of microvillus elongation), and subsequently elongate again about midway between fertilization and first cell division (the “second burst” of elongation). The second burst occurs during a discrete 30-min period and results in some microvilli being as long as 10 μm, although the average length is about 1.8 μm. The surface area of the egg following the second burst is about 2.7 times the area of the unfertilized egg.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号