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城市森林生态学是一门崭新的边缘交叉学科 ,它是随着城市化的发展 ,城市环境质量日益恶化背景下产生的 .196 2年美国政府在户外娱乐资源调查报告中 ,首次提出“城市森林”(urbanforest)概念 ,196 5年编制城市森林发展规划 ,1972年国会通过了“城市森林法” .嗣后引起世界各国科学家的关注 .我国城市森林研究起步较晚 ,2 0 0 2年由我国城市森林生态学家何兴元研究员和美国南方大学城市森林系宁祝华教授主编了我国第一部城市森林生态学专著———《城市森林生态研究进展》 ,它是我国城市森林生态学理论研究基础和实践精华 .已于 2 0 0 2年由中… 相似文献
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城市森林生态学是一门崭新的边缘交叉学科 ,它是随着城市化的发展 ,城市环境质量日益恶化背景下产生的 .1962年美国政府在户外娱乐资源调查报告中 ,首次提出“城市森林”(urbanforest)概念 ,1965年编制城市森林发展规划 ,1972年国会通过了“城市森林法” .嗣后引起世界各国科学家的关注 .我国城市森林研究起步较晚 ,2 0 0 2年由我国城市森林生态学家何兴元研究员和美国南方大学城市森林系宁祝华教授主编了我国第一部城市森林生态学专著———《城市森林生态研究进展》 ,它是我国城市森林生态学理论研究基础和实践精华 .已于 2 0 0 2年由中国… 相似文献
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城市森林生态学是一门崭新的边缘交叉学科 ,它是随着城市化的发展 ,城市环境质量日益恶化背景下产生的 .196 2年美国政府在户外娱乐资源调查报告中 ,首次提出“城市森林”(urbanforest)概念 ,196 5年编制城市森林发展规划 ,1972年国会通过了“城市森林法” .嗣后引起世界各国科学家的关注 .我国城市森林研究起步较晚 ,2 0 0 2年由我国城市森林生态学家何兴元研究员和美国南方大学城市森林系宁祝华教授主编了我国第一部城市森林生态学专著———《城市森林生态研究进展》 ,它是我国城市森林生态学理论研究基础和实践精华 .已于 2 0 0 2年由中… 相似文献
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我认识王先生是在 4 0年前 ,那时吴襄教授 (我的生理学启蒙老师 )在与王先生合作编写生理学教科书时邀我去做助手。两年以后 ,王先生借助中央“为专家配助手”的政策 ,通过卫生部 ,把我调入北医。我很惭愧 ,调入北医生理系后只帮王先生带了1~ 2个研究生 ,即应国家号召离开消化研究室从事针麻原理研究。迄今不觉三十余载 ,没有为王先生做好消化生理的科研助手 ,只是在生理学教学上尽了微薄之力。但在学术思想上 ,我亲身领受王先生的教诲 ,对他产生了深深的敬佩之情 ,这在多方面影响了我的一生。东西方哲学的完美结合 王先生为人处世宽以… 相似文献
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森林转型是指森林覆盖率由净减少到净增加的过程。中国森林早在20世纪80年代就进入了转型期,然而,中国热带地区的总森林覆盖率虽呈增长趋势,但依旧存在着天然林大量被毁的现象。鉴于天然林对森林生态系统功能的重要作用,本研究通过加入森林类型分类的内容,以西双版纳为例探讨其森林转型的真实特征。结果表明:森林转型理论单纯以“总森林”覆盖率为研究对象,忽视了其他森林类型的动态变化,甚至掩盖了“天然林”的真实动态变化。西双版纳的森林转型主要是人工种植林的扩张所致,只是树木数量统计上的转型。事实上,自1988年以来,西双版纳的天然林一直在锐减。所以建议未来关于森林转型的研究应将“森林”区分成不同的森林类型加以研究。 相似文献
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不同植被类型森林火灾及雷击火自组织临界性 总被引:4,自引:0,他引:4
利用黑龙江省大兴安岭林区呼中区 196 5~ 2 0 0 2年的雷击火数据、黑龙江省 1981~ 2 0 0 0年森林火灾数据及森林资源数据 ,对雷击造成的森林火灾的自组织临界性及不同植被类型条件下的自组织临界性作了研究 ,比较了在不同尺度和植被类型条件下火干扰的自组织临界性、自相似性 ,并与传统的森林火灾元胞自动机模型模拟的结果进行比较。结果表明 :中国黑龙江省不同森林类型的火干扰具有自组织临界行为 ,森林可燃物已经达到临界状态 ,其临界值在 1.8~ 2 .86之间 ,具有自相似性 ;当森林的面积过小时 ,森林火灾的“面积 -频率”分布曲线上会出现频率峰 ,表现出“有限面积效应”现象。 相似文献
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城市森林生态学的基本理论与研究方法 总被引:32,自引:5,他引:32
随着世界经济的发展和城市人口的增加,城市环境问题严重阻碍了城市可持续发展,形成了城市森林生态学这一新学科,森林生态学,景观生态学,园林学和人类生态学4种学科的相关理论相互融合构成了城市森林生态学的理论基础,城市森林生态学的形成使人们从生态系统的角度审视城市的发展,并把生物环境即人类及所有植物和动物的群体视为这个系统的一个要素,引出了“城市森林”的概念,本文较系统地介绍了城市森林生态学的基本概念,主要研究内容。理论基础及基本原理,研究方法及其发展展望。 相似文献
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中国林学会森林采运学会于1986年6月9日至14日在吉林市召开了“以森林生态为基础的森林采运学术讨论会”,参加会议代表来自四川、湖南,江苏、辽宁、吉林、黑龙江、内蒙古和北京等8省、市、区的44名代表。吉林市林学会会员和吉林林学院部分师生共120多人参加了会议,这是一次多学科的综合性的学术讨论会,也是教学、科研、生产三结合的学术会议。中国林学会副理事长陈陆圻教授致开幕词,指出会议的主要内容有三个方面:1.围绕会议主题,展开学术争论,达到学术交流的目的;2.讨论北京林业大学与吉林林学院协作在蛟河教学实验林场拟定的森林生态型主伐方式与采运工艺的科学试验方案,使理论密切联系生产实际;3.落实编写以森林生态为理论基础的森林采运学计划。 相似文献
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<正>我和东北森林结下的是一段不解之缘.这里,是我追求心中绿色的梦的起点,也是我心灵的驿站.在我从事林业研究60年的过程中,有机会到几十个国家进行森林参观和考察,科学研究的方向和地点也几经变迁,但我与东北森林的联系却是绵延不断.除了对这里山山水水的热爱,还有那人际间的情愫.每提到东北的森林,总会使我联想起在自己科学道路上引我入门的师长、科学研究中亲密的伙伴、那些曾与我共同在艰苦条件下患难与共的学生以及当地给了我浓郁友情的淳朴的林业工作者们. 相似文献
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A new polynitro cage compound 2, 4, 6, 8, 10, 12, 13, 14, 15-nonanitro-2, 4, 6, 8, 10, 12, 13, 14, 15-nonaazaheptcyclo [5.5.1.1(3,11).1(5,9)] pentadecane (NNNAHP) was designed in the present work. Its molecular structure was optimized at the B3LYP/6-31 G(d,p) level of density functional theory (DFT) and crystal structure was predicted using the Compass and Dreiding force fields and refined by DFT GGA-RPBE method. The obtained crystal structure of NNNAHP belongs to the P-1 space group and the lattice parameters are a = 9.99 ?, b = 10.78 ?, c = 9.99 ?, α = 90.01°, β = 120.01°, γ = 90.00°, and Z = 2, respectively. Based on the optimized crystal structure, the band gap, density of state, thermodynamic properties, infrared spectrum, strain energy, detonation characteristics, and thermal stability were predicted. Calculation results show that NNNAHP has detonation properties close to those of CL-20 and is a high energy density compound with moderate stability. 相似文献
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Summary Concentration of N, P, K, Ca, Mg and S in summer groundnut crop was higher than in kharif while Zn, Fe, Mn and Cu contents were higher in summer crop. Kernel's N, P and Zn; Leaflet's Ca and Mn; Stem's K and Fe; Root's S and Cu and Petiole's Mg contents were highest. Shell's N, P, K, Mg, S, Zn and Cu; Kernel's Ca, Fe and Mn contents were the least. N, P, K, S, Zn and Cu concentrations decreased linearly as the crop grew. Ca, Mg, Fe and Mn concentrations did not display any distinct pattern. Ca concentration was positively correlated with pod yield in both the seasons. 相似文献
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The variation with age of the 18 trace element mass fractions and some histological characteristics of intact prostate glands of 50 subjects aged 0–30 years was investigated by instrumental neutron activation analysis, inductively coupled plasma atomic emission spectrometry, and a quantitative morphometric analysis. Mean values ± standard error of the mean (M ± SΕΜ) for the mass fractions (in milligrams per kilogram wet tissue) of these trace elements in pre-puberty were: Al 28.5 ± 9.0, B 0.40 ± 0.11, Ba 1.48 ± 0.44, Br 10.5 ± 1.5, Ca 241 ± 30, Cl 3,203 ± 278, Cu 3.51 ± 0.89, Fe 33.7 ± 4.1, K 2,364 ± 145, Li 0.020 ± 0.004, Mg 153 ± 23, Mn 0.46 ± 0.06, Na 2,286 ± 130, P 1,391 ± 100, S 1,698 ± 132, Si 62 ± 11, Sr 0.38 ± 0.08, and Zn 27.6 ± 2.3. During puberty and postpuberty, when there is a significant increase in circulating androgens, the mean values were: Al 7.2 ± 1.4, B 0.21 ± 0.05, Ba 0.25 ± 0.06, Br 5.8 ± 1.0, Ca 433 ± 81, Cl 2,314 ± 201, Cu 1.77 ± 0.13, Fe 20.9 ± 1.6, K 2,585 ± 118, Li 0.0088 ± 0.0014, Mg 232 ± 27, Mn 0.34 ± 0.04, Na 1,875 ± 107, P 1,403 ± 98, S 1,673 ± 73, Si 22.2 ± 3.1, Sr 0.22 ± 0.03, and Zn 93.3 ± 8.9. Mean values (M ± SΕΜ) of percent volumes (%) of the stroma, epithelium and lumen in the prostate before puberty were 73.4 ± 2.6, 20.4 ± 1.7, and 4.45 ± 0.94, respectively, versus 46.5 ± 2.5, 38.5 ± 1.9, and 14.9 ± 1.2 during puberty and postpuberty. This work’s results confirm that the Zn mass fraction in prostate tissue is an androgen-dependent parameter. For the first time it has been demonstrated that the glandular lumen is a main pool of Ca, Mg, and Zn accumulation and that the stroma is a main pool of Al, B, Ba, Br, Cl, Cu, Fe, Mn, Na, and Si accumulation in the normal human prostate, for the age range 0–30 years. It was concluded that the Ca, Mg, and Zn binds tightly within the prostatic fluid, because the volume of glandular lumen reflects the volume of prostatic fluid. 相似文献
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The goal of this article was to establish reference ranges of the concentration of trace elements in human serum and to compare
these results with those reported by other authors. We describe the sample preparation and measurement conditions that allow
the rapid, precise, and accurate determination of Al, As, B, Be, Cd, Co, Cu, Fe, Li, Mn, Mo, Ni, Rb, Se, Sr, and Zn in human
serum samples (n=110) by inductively coupled plasma-mass spectrometry (ICP-MS). Accuracy and precision were determined by analyzing three
reconstituted reference serum samples by comparison with other methods and by the standard addition procedure.
The advantages of the ICP-MS method include short time of analysis of the elements mentioned, low detection limit, high precision,
and high accuracy. Disadventages include a high risk of contamination due to the presence of some of the elements of interest
in the environment, the relatively delicate sample handling, and the high cost of the equipment. 相似文献
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G. V. Iyengar 《Biological trace element research》1987,12(1):263-295
This report attempts to formulate reference ranges of elemental concentrations for 15 trace elements in selected human tissues
and body fluids.
A set of samples consisting of whole blood, blood serum, urine, milk, liver, and hair were chosen and considered for 15 elements
of biological significance: As, Cd, Co, Cr, Cu, F, Fe, I, Hg, Mn, Mo, Ni, Pb, Se, and Zn. The results represent wholly or
partially data received from 40 countries of the global regions of Africa, Asia, Europe, North, South, and Central America,
Australia, and New Zealand.
This survey, even if qualitative, has been useful in demonstrating certain trends of trace-element scenarios around the world.
It is of course recognized that both diet and environment exert a strong influence on the distribution pattern of several
elements, such as As, Cd, Mn, Pb, Se, and Zn. A limited comparison of the available information on soil status of different
countries reflected some interesting associations for elements, such as Mn and Zn.
Importantly, this study revealed that only a few countries were in a position to identify a reasonable amount of data on samples
requested for this project. Regretably, for a number of countries, any dependable data for even such essential elements as
Cu, Fe, and Zn were not available.
In view of the nutritional importance of many elements, the time is ripe for concerted efforts by intergovernmental agencies
to initiate investigations or commission task forces/projects to generate reliable reference data for selected global regions,
which sadly lack data of any kind at present. 相似文献
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Vladimir Zaichick Sofia Zaichick Vasilii Karandashev Sergey Nosenko 《Biological trace element research》2009,129(1-3):107-115
The effect of age and gender on major, minor, and trace element contents in the intact rib bone of 80 relatively healthy 15–55-year-old women and men was investigated. Contents or upper limit of contents of 16 chemical elements in the rib bone were determined by inductively coupled plasma atomic emission spectrometry (ICP-AES). Mean values (M?±?SΕΜ) for the mass fraction of Ba, Ca, Cu, Fe, K, Li, Mg, Na, P, S, Sr, and Zn (milligram per kilogram of dry bone) were as follows: 2.54?±?0.16, 171,400?±?4,050, 1.35?±?0.22, 140?±?11, 1,874?±?71, 0.049?±?0.011, 2,139?±?38, 5,378?±?88, 75,140?±?1,660, 1,881?±?51, 291?±?20, and 92.8?±?1.5, respectively. The upper limits of contents of Al, B, Mn, and V were <7.20, <0.65, <0.36, and <0.03, respectively. Statistically significant tendency for the Ca, Mg, and P content to decrease with age was found in the human rib bone, regardless of gender. The mass fraction of Fe in the male rib bone increases with age. It was shown that higher Ca, Mg, Na, P, and Sr mass fractions as well as lower Fe content were typical of female ribs as compared to those in male ribs. 相似文献
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Oral cancer is one of the main causes of cancer-related deaths in South-Asian countries. There are very limited treatment options available for oral cancer. Research endeavors focused on discovery and development of novel therapies for oral cancer, is necessary to control the ever rising oral cancer related mortalities. We mined the large pool of compounds from the publicly available compound databases, to identify potential therapeutic compounds for oral cancer. Over 84 million compounds were screened for the possible anti-cancer activity by custom build SVM classifier. The molecular targets of the predicted anti-cancer compounds were mined from reliable sources like experimental bioassays studies associated with the compound, and from protein-compound interaction databases. Therapeutic compounds from DrugBank, and a list of natural anti-cancer compounds derived from literature mining of published studies, were used for building partial least squares regression model. The regression model thus built, was used for the estimation of oral cancer specific weights based on the molecular targets. These weights were used to compute scores for screening the predicted anti-cancer compounds for their potential to treat oral cancer. The list of potential compounds was annotated with corresponding physicochemical properties, cancer specific bioactivity evidences, and literature evidences. In all, 288 compounds with the potential to treat oral cancer were identified in the current study. The majority of the compounds in this list are natural products, which are well-tolerated and have minimal side-effects compared to the synthetic counterparts. Some of the potential therapeutic compounds identified in the current study are resveratrol, nimbolide, lovastatin, bortezomib, vorinostat, berberine, pterostilbene, deguelin, andrographolide, and colchicine. 相似文献