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 703 毫秒
1.
Ranalisma rostratum (Alismataceae) is an endangered aquatic plant, and now there is only one population existing in China. In its natural habitat, Huli marsh in Chaling, Hunan province, the best growing plants have been observed at microsites where the water depth is 5∼10cm, and the plants grow in emergent form.R. rostratum reproduces asexually or sexually. The recruitment of asexual propagules into population is a very important way to maintain the natural population size. Although seed production does not appear to limitR. rostratum, restricted dispersal of propagules and seeds, low seed viability, low germinability, slow growth of seedlings under all conditions, and habitat loss due to agriculture appear to be more important reasons for the endangerment of this plant. Supported by the national Natural Science Foundation of China Wang Jianbo: born in 1964, Ph. D, Associate professor  相似文献   

2.
The floristic elements and the geographical distribution are analyzed in this paper based on statistics of elements of rare and endangered plants in Tibet. The results have been gained as following:① According to ““““the National Important Wild Conservative Plants List (List 1)““““ and ““““the National Important Wild Conservative Plants List (List 1)““““, there are a total of 54 plant species (48 genera and 33 families); ② The geographical elements are very complicated in Tibet with 12 of 15 distribution patterns of genera classified byacademician Wu; ③ There are obvious temperate genera with 28 genera accounting for 60.40% of the total genera; ④ There are abundant endemic speciesaccounting for 18.52% of total species but poor endemic genera; ⑤ The geographical distribution is uneven and a great of species distribute in the areas be-tween 1 000 m and 3 500 m above sea level; ⑥ To protect the rare and endangered plants efficiently, six conservation measures are proposed, and 35 species are suggested for the conservative plants of the autonomous conservation level.  相似文献   

3.
缪振鹏  丁莉 《广西科学》2019,26(1):146-151
长梗吊石苣苔Lysionotus longipedunculatus (W.T. Wang) W.T. Wang是我国吊石苣苔属中的一个比较罕见的物种,目前濒危等级被评估为极危CR Blac (ⅰ,ⅱ,ⅴ),而同属的吊石苣苔L. pauciflorus Maxim.分布范围非常广泛、生境变化多样,濒危等级为无危LC。本研究通过筛选出16个微卫星位点对长梗吊石苣苔的两个居群进行遗传多样性研究,并对比相近地区的吊石苣苔居群,比较研究导致长梗吊石苣苔濒危的原因。结果显示二者的遗传多样性都比较低,有较高自交现象,但吊石苣苔具有明显的走茎,可以有效地克隆繁殖,相较之下,长梗吊石苣苔较弱的克隆繁殖能力可能是导致其濒危的原因之一。  相似文献   

4.
The relaxation of the highly vibrationally excited CO (v = 1–8) by CO2 is studied by timeresolved Fourier transform infrared emission spectroscopy (TR FTIR). 193 nm laser photolysis of the mixture of CHBr3 with O2 generates the highly vibrationally excited CO(v) molecules. TR FTIR records the intense infrared emission of CO(v→v-1). The vibrational populations of each level of CO(v) have been determined by the method of spectral simulation. Based on the evolution of the time resolved populations and the differential method, 8 energy transfer rate constants of CO(v = 1–8) to CO2 molecules areobtained: (5.7±0.1), (5.9±0.1), (5.2±0.2), (3.4±0.2), (2.4±0.3), (2.2±0.4), (2.0±0.4) and (1.8±0.6) (1014 cm3 · molecule−1 · s−1), respectively. A two-channel energy transfer model can explain the feature of the quenching of CO(v) by CO2. For the lower vibrational states of CO, the vibrational energy transfers preferentially to the u3 mode of CO2 For the higher levels, the major quenching channel changes to the vibrational energy exchange between CO(v→v-1) and the u1 mode of CO2.  相似文献   

5.
0 IntroductionThetechnologyofthermalanalysishasbeenwidelyusedinthestudyofthermalbehaviorandthermalcharacterofsolidstatereaction ,theprimaryintentionofthermalanalysiskineticsistoestablishseparatevaluesofapparentactivationenergyE ,themostprobablemechanism g(α)andthepre exponentialfactorA ,meanwhilethedeterminationofg(α)hasgraduallybeenthefocusofthisfield .Inthisfield ,therearemostlygeneralkineticsmethodsused presently ,suchasCoats Redfern’s[1 ] integralmethod ,Achar’s[2 \〗differentialmet…  相似文献   

6.
为加强南宁植物园珍稀濒危植物迁地保护及应用工作,通过实地调查和资料搜集,对南宁植物园珍稀濒危植物的种类、组成和多样性进行分析与评估,并对园林应用的可能性进行探索。结果表明,(1)南宁植物园共有珍稀濒危维管植物37科66属234种,均属于国家重点保护野生植物;其中属于《濒危野生动植物种国际贸易公约》(CITES)的有5科17属134种;属于世界自然保护联盟(IUCN)濒危物种红色名录的有33科62属210种;属于极小种群的有10科13属32种;属于广西壮族自治区重点保护植物的有1种。(2)园林应用上可分为生长型(常绿乔木、落叶乔木、常绿灌木、多年生草本)、观赏型(观花、观叶、观形、观果、观茎和芳香植物)和生态型(喜阳、中性、耐阴)3种。(3)兰科(Orchidaceae)、苏铁科(Cycadaceae)和山茶科(Theaceae)种数最高,分别为126种、22种和12种。(4)南宁植物园中珍稀濒危植物花期集中在4-8月,果期集中在9-11月,能较好地应用于景观。总体而言,南宁植物园迁地保护植物偏向于裸子植物和受威胁植物种类。目前突出的问题是珍稀濒危植物数量仍较少,对区域性国家重点保护野生植物种质资源的搜集尚不全面,种类多样性仍有待提高。园中适应性较好和普通的种类达95.30%,在园林应用方面可进一步结合优势作出更为精细的管理。本研究为南宁植物园珍稀濒危植物迁地保护、后期回归与园林应用提供了科学基础和参考。  相似文献   

7.
Ternary inclusion complexes β-cyclodextrin (β-CD), rare earth metal ions (YbCl3, YCl3), and 1,8-naphthalene- diamine/1,5-naphthalenediamine are synthesized in basic aqueous media, which are characterized via 1H NMR and IR spectroscopy. The stoichiometric proportion of β-CD:YbCl3:1,5-naphthalenediamine is 2:1:2, that of β-CD:YCl3:1,8-naphthalenediamine is 2:1:1, and that of β-CD:YbCl3:1,8-naphthalenediamine is 2:1:1. The IR spectroscopy of the ternary inclusion complexes in the range of 935–1 000 cm−1 reveals the existence of the coordinate bond M—O or M—N. The possible conformations of the ternary inclusion complexes are depicted. Biography: JIANG Huiming(1972–), male, Associate professor, research direction: molecular complex chemistry, supramolecular chemistry.  相似文献   

8.
This study is aimed to investigate and analyze the vegetation landscape around Rivers of Hou-lung, Fa-tz, Da-li, Ching-shuei and Gau- ping, and to select the suitable plant species that could be applied for the area of riverbank ecological engineering in Taiwan. Studying the vegetation established the key point and procedure of ecological engineering in the riverside and revetment, to compile and edit the dominant plants' types, life form, propagating method, root systems' characteristics and functions for soil conservation. This research choses three dominant plants for roots strength test. The fitting models of plants pulling resistance(Rp, kg) between plant height (H, cm), diameter near ground (Dn, mm), diameter above ground 100 mm (Da, mm), The research finished the relative abundant, types and cluster analysis of riverbank dominant plants that generalize vegetative distribution and ecological restoration for different river types to apply and manage in Taiwan.  相似文献   

9.
Panxi Area is abundant in plant resources, among which toxic plants are of great value in terms of exploitation. This paper is an initiative study (via field as well as literature investigation) of the categories, distributions, and reserves of toxic plant resources in Panxi Area. The study reveals that there are 51 families (210 species) of toxic plants evenly distributed in Panxi Area, of which more than 40 species grow in all counties in the area, and more than 14 species total a reserve more than 1.0×10^5 kg. These toxic plants are of great applications to medicine, gardening, biopesticide industry, environmental engineering, and oil manufacturing. Rhododendron molle, Anisodus acutangulus, Arisaema erubesocens, Stellera chamaejasme, Rhytolacca acinosa, Rheum officinale, and Azadiralta indica etc are the typical toxic plants with great value of exploitation in Panxi Area.  相似文献   

10.
The binding reaction between 10-hydroxycamptothecin (10-HCPT) and human serum albumins (HSA) is studied by means of fluorescence spectroscopy, UV-Vis absorption spectrum, 1H NMR spectrum, and molecular simulation. The results indicate that the binding reaction of 10-HCPT and HSA is a single static quenching process, and the binding equilibrium constant for 10-HCPT binding with HSA is estimated K 0= 4.93×104 L · mol−1 at 25 °C with the molar ratio of 1:1. The distance (r) and energy transfer efficiency (E) between donor (HSA) and acceptor (10-HCPT) are obtained as follows, r =3.51 nm; E =0.27. The enthalpy change (ΔH ) and entropy change (ΔS ) are calculated at different temperatures, and the hydrophobic force and shidipole force are the functions in the reaction. The results show that 10-HCPT binds within the subdomain II A of HSA by the hydrophobic force, and the 10-OH and 20-OH of 10-HCPT bind with both residue Leu-238 of HSA and Ala 291 of HSA by hydrogen bonds. Biography: LI Guizhi(1962–), female, Associate professor, research direction: organic analysis.  相似文献   

11.
0 IntroductionMolecularimprinting[1 ] isatechniquebasedoncreatingcavities,inahighlycross linkedpolymermatrix ,thatcorrespondtothesizeandshapeoftheprintmolecule .Themolecularrecognitioneffectisaconsequenceofthepresenceinthepolymerizationmixtureoftemplatemoleculescapableofestab lishingnon covalentinteractionswithmonomerandcross linkers.Molecularlyimprintedpolymers (MIPs)havebeenusedaschromatographicstationaryphases[2 ,3] includingcapillaryelec trochromatography ,asselectivematerialsforbiosenso…  相似文献   

12.
Scalar multiplication [n]P is the kernel and the most time-consuming operation in elliptic curve cryptosystems. In order to improve scalar multiplication, in this paper, we propose a tripling algorithm using Lopez and Dahab projective coordinates, in which there are 3 field multiplications and 3 field squarings less than that in the Jacobian projective tripling algorithm. Furthermore, we map P to(φε^-1(P), and compute [n](φε^-1(P) on elliptic curve Eε, which is faster than computing [n]P on E, where φε is an isomorphism. Finally we calculate (φε([n]φε^-1(P)) = [n]P. Combined with our efficient point tripling formula, this method leads scalar multiplication using double bases to achieve about 23% improvement, compared with Jacobian projective coordinates.  相似文献   

13.
盐胁迫对红鳞蒲桃苗木生长和生理特性的影响   总被引:1,自引:0,他引:1       下载免费PDF全文
【目的】评价盐胁迫下红鳞蒲桃(Syzygizan hancei)苗木的生理耐受性。【方法】选择当年生红鳞蒲桃盆栽苗木为材料,研究6种NaCl盐分浓度(0%、0.2%、0.4%、0.6%、0.8%、1.0%)下红鳞蒲桃幼苗高生长、地径生长、叶片质膜透性、游离脯氨酸含量、可溶性糖含量、过氧化氢酶(CAT)活性、叶绿素含量的变化特征。【结果】随着NaCl浓度的增加,红鳞蒲桃苗木的高增长量逐渐降低,在浓度0.4%时下降显著;NaCl浓度对苗木的地径增长量影响不大;细胞质膜透性对盐胁迫具有较强的耐性,NaCl浓度在0.8%以下时,叶片的相对电导率差异不显著;游离脯氨酸和可溶性糖含量在NaCl浓度为0.4%时显著增加,其后维持在一定水平;CAT酶活性对盐胁迫较为敏感,在浓度0.2%时即显著增强;叶绿素含量则随着NaCl浓度的增加表现出先升后降的变化趋势。【结论】0.4%NaCl浓度是影响红鳞蒲桃苗木生理特性的关键。  相似文献   

14.
0Introduction Biologicaldiversityconcernedwiththesumofvariouslivingbeingsandtheirprocesses,aswellasthebasisofharmonious coexistencebetweenmanandnatureplaysanimportantroleinecology,economy,esthetics,ethics,etc.Duetodeteriorationofglobal environment,acceler…  相似文献   

15.
The Chinese alligator, Alligator sinensis, is a critically endangered species. A conservation project of gene resources for an endangered species first involves the preservation of organs, tissues, gametes, genomic DNA libraries and cell lines. The present study is the first to establish and cryopreserve cell lines of liver, heart and muscle tissues from the Chinese alligator. The study revealed that there was a large discrepancy in cell migration time in primary cultures among liver (11-12 d), heart (13-14 d) and muscle (17-18 d) tissue pieces. The differences in time in primary cell culture suggested that it was relatively easy to build visceral-derived cell lines for reptiles. Biological analysis showed that the population doubling time for thawed cells was approxi- mately 36 h. Karyotyping revealed that the frequency of Chinese alligator cells showing chromosome number as 2n=32 was 88.6%-93.4%. Chinese alligator cell lines established here provide a vital resource for research and are likely to be useful for protection of this rare and critically endangered species. Furthermore, the establishment of these methods may supply technical and theoretical support for preserving genetic resources at the cellular level for other reptile species.  相似文献   

16.
This paper is an extension of the application of neighborhood interference model--being modified--to the study of the interference between forest plants and herbaceous plants. The exploration of the neighborhood interference between triploid Populus tomentosa and Lolium multiflorum shows that the interference of Lolium multiflorum on triploid populus tomentosa is positive, with the primary interference factor living weight, and secondary factor cover degree; the growth of an individual tree is affected by the number, height, and coverage of the Lolium multiflorum; the more dense the coverage of the Lolium multiflorum in a certain area, the taller, faster and more trees will grow as a result of a greater positive neighborhood interference. The modified neighborhood interference model well serves as an effective approach to extend the application of neighborhood interference researches.  相似文献   

17.
In this paper, we study the logarithmic Sobolev inequalities for two-sided birth-death processes. An estimate of the logarithmic Sobolev constant α for a two-sided birth-death process is obtained by the Hardy-type inequality and a criteria for α is also presented. Biography: YANG Qingshan (1981–), male, Ph.D. candidate, research direction: large deviation principle.  相似文献   

18.
The investigation was conducted on the spatial and temporal distributions of soil organic mater (SOM) in the mixed plantations of alder (Aluns crernastogyne) and cypress (Cupressus funebris ) (MPAC), which distributed in the hilly areas of central Sichuan Basin (HACSB). The results show that: (1) the spatial distribution of SOM among different sites at the same age are not significant before 15-year-old, but significant at 20-year-old, and not significant again after 25-year-old; (2) the SOM contents in 0-15 cm and 15-30 cm layers increase sharply from 10- to 15-year-old, and decline gradually from 15- to 30- year-old; the SOM contents of the 30-year-old PCP were 80. 38% and 78.42% higher than that of the 10-year-old, but 29.16% and 53.37% lower than that of 15-year-old in the 0-15 cm and 15-30 cm layers, respectively. The decrease of SOM contents would lead to the degradation of soil fertility and the decline of forest productivity.  相似文献   

19.
For an odd integer n ≥ 7, this paper presented a class of n-variable rotation symmetric Boolean functions (RSBFs) with optimum algebraic immunity. The nonlinearity of the constructed functions is determined.  相似文献   

20.
Isoetes sinensis Palmer (Isoetaceae) is an aquatic or amphibious plant that is critically endangered in China. Previous studies have revealed the crassulacean acid metabolism (CAM)-like photosynthetic pathway occurs commonly in submerged leaves in genusIsoetes. Water chemistry parameters and the titratable acidity content of the plant extract were measured from samples obtained in the early morning (7∶00) and late afternoon (15∶00) from twoI. sinensis populations in China. One population occurs in the eulittoral zone of a freshwater tidal river at low elevation (134 m) and another occurs in a densely vegetated, high elevation (1 100 m) alpine shallow pool. Significant differences in pH and titratable acidity of the plant extract were detected between the morning and afternoon samples. These changes are associated with diurnal changes in water chemistry. Our results provide the first evidence for the existence of the CAM pathway in the East Asian endemicIsoetes sinensis Palmer. The magnitude of fluctuations in the titratable acidity of the plant extract may be correlated with the severe carbon limitation imposed on the plants by its aquatic habitat. Foundation item: Supported by the State Key Basic Research and Development Plan (G2000046805) Biography:Pang Xin-an (1974-), male, Master candidate, research direction: conservation biology.  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