共查询到20条相似文献,搜索用时 15 毫秒
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广东深圳塘朗山郊野公园共有野生维管植物144科423属611种,分别占广东省维管植物280科1589属5737种的51.4%、26.7%和10.65%;其中蕨类省植物21科29属33种,裸子植物3科3属4种,被子植物120科391属574种,被子植物占绝对优势。国家重点保护野生植物共计7科7属7种,占广东省国家重点保护野生植物的10.9%;珍稀濒危植物有4科5属5种,占广东省珍稀濒危植物67种的7%。公园中经济植物可分为12类,分别是药用植物321种,用材树种65种,观赏植物60种,纤维植物41种,野生水果33种,油脂植物38种,饲料植物42种,鞣料植物42种,野菜植物25种,农药植物27种,芳香植物26种,淀粉植物23种,保健植物19种,染料植物13种,有毒植物10种,蜜源植物5种。 相似文献
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江西木兰科植物的初步整理 总被引:3,自引:1,他引:2
通过野外采集及标本的整理鉴定, 确认江西产木兰科植物7 属22 种1 亚种, 其中3 种为江西特有种, 5 种为江西地理新分布。对各分类群进行了分类检索, 记载了其地理分布, 并列出凭证标本。 相似文献
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浙江磐安种子植物区系的特征分析 总被引:5,自引:0,他引:5
磐安约有野生种子植物 1 44科 ,62 7属 ,1 2 98种 (包括种以下分类单位 )。其中世界成分的属 67个 ,占总属数的 1 0 .69% ,热带属 2 2 7个 ,占 36.2 0 % ,温带属 32 1个 ,占 5 1 .2 0 % ,中国特有属 1 2个 ,占 1 .91 %。磐安气候温暖湿润 ,植物种类丰富 ,古老、孑遗、珍稀植物多 ,单种属和少种属占有较大比重 ;优势科、优势属明显 ,优势科 34个 ,共含有 393属 ,776种 ,分别占总属数总种属的 62 .7% ,70 .3% ,优势属 1 0个 ,共含有 1 44种 ,分别占总属数总种数的 1 .6% ,1 1 .1 % ,其中樟科、壳斗科等是该区系的表征科 ;植物分布类型多样 ,地理成分复杂 ,温带成分和热带成分占优势 ,是亚热带分布的北缘 ,与世界各地有广泛的联系 相似文献
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G. Rosenkranz 《Biometrical journal. Biometrische Zeitschrift》1984,26(8):839-847
Linear rank test statistics are applied to the problem of estimating a treatment effect if two sets of censored failure time data are compared and the distributions of the log-failure times of the two samples are assumed to differ only in location. Rank tests for this accelerated failure time model are reviewed and Hodges-Lehmann type estimates for the shift parameter are proposed. Properties of these estimates are investigated, computational aspects are discussed and an example is presented. 相似文献
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潮汕地区农药植物资源十分丰富。初步调查统计共有 88科 2 39种 ,其中蕨类植物 4种 ,裸子植物 6种 ,被子植物2 2 9种 ,这些农药植物均具有杀虫作用。本文对潮汕地区农药植物的研究和合理开发利用提出了若干建议 相似文献
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Different types of phase coupling between and within EEG signals are theoretically explained and coupling-related analysis strategies are reported. Effects of synchronization have been distinguished from effects signal transfer (propagation), where both are designated by a phase coupling. Six examples of phase coupling analysis are presented. The EEG data are derived from our previous investigations and analysis results are complemented by modelling and simulation studies. 相似文献
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广西金钟山鸟类保护区鸟类多样性初步研究 总被引:7,自引:0,他引:7
本文共记录到金钟山鸟类274种,分别隶属于18目57科,其中陆生鸟类251种,水鸟23种;以留鸟为主,共157种;候鸟、旅鸟分别为104种、13种;东洋种为优势类群,共有171种,古北种和广布种分别为4种、27种。这些鸟类中有国家重点保护鸟类39种,中国特有种鸟类3种,列入世界自然保护联盟红皮书名录中的鸟类5种,列入中国濒危动物红皮书名录中的鸟类20种,列入CITES附录中的鸟类34种。本文还对金钟山鸟类保护区的5种不同生境类型的鸟类种类组成作了比较,结果表明灌丛+农田的鸟种多样性指数最高,为3.04;水域的鸟种多样性指数最低,为2.14。 相似文献
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WILLIAM LOUIS STERN F.L.S. 《Botanical journal of the Linnean Society. Linnean Society of London》1997,124(2):121-136
Leaves in Orchidinae are essentially glabrous; anticlinal walls of foliar epidermal cells arc basically straight-sided to curvilinear, and cells arc fundamentally polygonal on both surfaces; adaxial cells are larger than abaxial cells. Stomata arc anomocytic and usually only abaxial and superficial; substomatal chambers are small to moderate; outer and inner guard cell ledges are mostly small. There is no hypodermis nor are there fibre bundles. Mesophyll is homogeneous, chlorcnchyma cells arc thin-walled, and intercellular spaces numerous. Crystalliferous idioblasts abound. Vascular bundles are collateral, organized in a single series. and lack associated sclerenchyma. Bundle sheath cells are thin-walled and chlorophyllous. Stems are glabrous; stomata arc frequent in one species, lacking in others. Cortical cells are oval to circular, thick-walled, and interspersed with triangular intercellular spaces. Ground-tissue cells are circular, and triangular intercellular spaces are present. Vascular bundles arc collateral and scattered throughout the ground-tissue or are absent from the central ground-tissue. Epidermis in absorbing roots is one-layered and non-velamcntous. Exodcrmal cells are thin-walled and dead cell walls bear tenuous scalariform bars; some species lack an exodermis. Outer cortical cells are polygonal and lack intercellular spaces; middle layer cortical cells are rounded with triangular intercellular spaces; inner layer cells are polygonal and lack intercellular spaces. Endodermis and pericycle are thin-walled and one-layered. Vascular cylinder is mostly 7–9-arch with xylcm and phloem components alternating regularly; vascular tissue is embedded in parenchyma; pith cells are parenchymatous, polygonal, thin-walled and lack intercellular spaces. Root tubers generally bear a velamen of variable thickness; bulbous-based unicellular hairs frequently form a dense mat; exodermal cells are thin-walled; dead cells have scalariform bars, passage cells are sparse. Ground-tissue consists of rounded water-storage and assimilatory cells interspersed with triangular or quadrangular intercellular spaces; peripheral cells arc polygonal lacking intercellular spaces. Vascular tissue consists of monarch to pentarch meristeles distributed thoughout the ground-tissue each surrounded by a uniscriale endodermis of thin-walled cells. Thin roots ofPlalanthera exhibit a typical central cylinder surrounded by a homogeneous cortex uninterrupted by meristeles; thicker roots show a central vascular cylinder and cortex in which meristeles are also present; in globoid root tubers there is no central cylinder, and the ground-tissue is replete with scattered meristeles. Because the central vascular cylinder in Platanthera gives rise to branches (meristeles), these represent components of a single vascular system and are not separate stelar entities as implied by the use of the term ‘polystele’. 相似文献
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Twenty-two pteridophytes (13 endemic and 9 non-endemic) from São Tomé e Príncipe (Gulf of Guinea) are evaluated as regards their rarity and conservation status. IUCN Red List Categories are assigned to these taxa. Eight taxa are Critically Endangered (CR), eleven taxa are Vulnerable (VU) and three taxa are Endangered (EN). Specific measures to conserve these rare pteridophytes are outlined. 相似文献
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采用同位素示踪和肠道离体灌流方法,研究了草鱼离体肠道对亮氨酸(Leu)、酪氨酸(Tyr)的吸收转运与利用。实验结果表明:当Leu浓度从1.0mmol/L增加到5.0mmol/L、10mmol/L时,肠道吸收转运的速度表现出“高浓度抑制”效应,运输到肠道外的比例为83%、66%和35%;合成肠道蛋白质的比例为2%、5%和13%;肠道组织内游离形式的比例为9%、28%和49%;其他形式的比例为6%、1%和3%。Tyr浓度从0.5mmol/L增加到1.5mmol/L、2.5mmol/L时,肠道对Tyr的吸收转运速度也随之增加,运输到肠道外的比例为52%、55%和55%;合成肠道蛋白质的比例为17%、15%和16%:肠道组织内游离形式的比例为7%、10%和16%;其他形式的比例为24%、20%和13%。肠道在吸收转运Leu和Tyr的同时,也利用它们合成蛋白质的和其他方面,Leu的吸收利用受灌流试验氨基酸浓度影响较大、而Tyr受影响较小;随着肠道内灌流的试验氨基酸浓度增加,吸收转运到肠道外的比例下降、留存于肠道内的比例增加,肠道合成的蛋白质绝对量也增加。
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Major aspects of algal modelling are defined.Prediction and explanation are suggested as mainobjectives. Examples of the development and use ofshort-term prediction and more general explanatoryalgal models for reservoirs are given. It is concludedthat good prediction and explanation are not likely tobe simultaneously achievable. Possible means ofassessing the capabilities of ecosystem models andmodelling are considered. Some suggestions as to howthe present situation may be coped with, and improved,are proposed. 相似文献
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桂西北典型喀斯特区生态服务价值的环境响应及其空间尺度特征 总被引:6,自引:0,他引:6
Study on ecosystem service values (ESVs) is the bridge of understanding ecosystem and economic decision-making. To investigate the response of ESVs to ambient environment and their spatial scales is an urgent work in the process of ecological restoration and sustainable development in southwest China. Based on the previous research results, the remote images, and weather data of 31 years (1975-2005), the response of ESVs to ambient environment and their spatial scales in a typical karst area of northwest Guangxi, China were evaluated with the method of empirical mode decomposition (EMD) in this paper. The results showed that ESVs had obvious variations with changes in elevation, rocky types and soil types, and had corresponding characteristics of spatial scales. The ESVs in middle and low elevation areas were higher, but they decreased due to human activities such as deforestation. The ESVs in peak-cluster depression areas were lower, and they would increase as influenced by policies such as returning farmland to forestland. The ESVs were influenced by rocky types, showing lower values but an increasing trend in the typical karst regions while higher values but a decreasing trend in non-karst regions. The average ESVs in the west part of the study region, which is not only the main nature reserve for rare wildlife species in Guangxi, but also one of the best preserved natural vegetation regions in China, were more than 15,000 RMB Yuan ha-1,. Comparatively, the ESVs were less than 10,000 Yuan ha-1 in the middle part of the region attributed to low vegetation coverage, serious peak-cluster depression and karst rocky desertification. After about 20 years, that is from 1985 to 2005, the ecosystem conditions had been improved and the ESVs had increased in the middle and eastern part of this study region. On the contrary, in most western part, which was dominated by subtropical evergreen broad-leaved forest, they had been worsened, and the balance values of ESVs were negative. As for the relationships of ESVs with rocky types and soil types, lime soil and red soil were the two main soil types that contributed to ESVs (The total contribution was above 60%, and it is 63.77%,64.37%,64.56%,64.91% respectively in the four years of 1985, 1990, 2000 and 2005.). The variance contribution of intrinsic mode function (IMF) and trend (R) showed that there were obvious special sales for ESVs in this study area, and the main spatial scales were about 2.7 km, 5.5 km, and 11.6 km. The variance contribution ratio was 12.29%, 11.26%, 11.49% respectively, and the trend (R) was high (17.74%). In conclusion, this study indicated that ecosystem conditions in the typical karst area were improved owing to the application of rocky desertification control policies, such as ecological migration and returning farmland to forestland. Besides, the main spatial scales of ESVs in the study area were the interactions of terrain, physiognomy, land use / land cover and human activities. 相似文献