Highly Functionalized Daphnane Diterpenoids from Trigonostemon thyrsoideum

Trigonothyrins A-C (1-3), which are highly functionalized daphnane diterpenoids, were isolated from the stems of Trigonostemon thyrsoideum. Compounds 1-3 represent the first examples of daphnanes with an oxygen-bridged four-membered-ring system, and a linkage mode of 12,13,14-orthoester. Compound 3 was observed to inhibit HIV-1 induced cytopathic effects. The EC50 value was 2.19 mu g/mL, and the therapeutic index (TI) was more than 90.

芒果扁喙叶蝉(Idioscopus incertus(Baker))生物学及其综合防治的研究

芒果扁喙叶蝉Idioscopus incertus (Baker)在云南元江干热河谷地区1年发生8-9代,世代重叠严重,以幼虫(若虫)、成虫越冬,越冬态不明显。4月中、下旬至5月上、中旬为第1个发生高峰期,是全年发生危害重、持续时间长的主要高峰期。7月下旬至8月上、中旬为第2个发生危害高峰期,对梢、叶的危害率分别为100%, 96.4%。采用综合防治措施后,其危害率分别降为4.7%,6.2%。

Study on fish hatchery and nurseries in Mymensingh, Bangladesh

In generally, fish hatchery and nursery owners having both hatchery and nursery facilities were financially stronger, well-educated and well-trained than only nursery ponds owners in Mymensingh aquaculture region. On the other hand, only nursery pond owners were more experienced in fish seed business than only hatchery owners. Most of the owners were satisfied with existing communication facilities. Lack of technical knowledge was one of the major constraints which could be solved by ensuring proper training. This business can be made more profitable providing loan to poor farmers and improving law and order situation.

Changes in phytoplankton communities and primary production

Lake Victoria is the second largest lake in the world (69000km2) by surface area, but it is the shallowest (69m maximum depth) of the African Great Lakes. It is situated across the equator at an altitude of 1240m and lies in a shallow basin between two uplifted ridges of the eastern and western rift valleys (Beadle 1974). Despite their tropical locations, African lakes exhibit considerable seasonality related to the alteration of warm, wet and cool, dry seasons and the accompanying changes in lucustrine stratification and mixing (Tailing, 1965; 1966; Melack 1979; Hecky& Fee 1981; Hecky& Kling,1981; 1987; Bootsma 1993; Mugidde 1992; 1993). Phytoplankton productivity, biomass and species composition change seasonally in response to variations in light environment and nutrient availability which accompany changes in mixed layer depth and erosion or stabilization of the metalimnion / hypolimnion (Spigel & Coulter 1996; Hecky et al., 1991; Tailing 1987). Over longer, millennial time scales, the phytoplankton communities of the African Great Lakes have responded to variability in the EastAfrican climate (Johnson 1996; Haberyan& Hecky, 1986) which also alters the same ecological factors (Kilham et al., 1986). Recently, over the last few decades, changes in external and or internal factors in Lake Victoria and its basin have had a profound inlluence on the planktic community of this lake (Hecky, 1993; Lipiatou et al., 1996). The lake has experienced 2-10x increases in chlorophyll and 2x increase in primary productivity since Tailing's observations in the early 1960s (Mugidde 1992, 1993). In addition to observed changes in the lake nutrient chemistry (Hecky & Mungoma, 1990; Hecky & Bugenyi 1992; Hecky 1993; Bootsma & Hecky 1993), the deep waters previouslyoxygenated to the sediment surface through most of the year are now regularly anoxic(Hecky et al., 1994).

云南国家级自然保护区存在问题研究

云南是我国生物多样性丰富的地区, 在生物多样性保护中扮演着重要角色而云南国家 级自然保护区在云南省自然保护区中又拥有较大比重, 分布在云南生物多样性关键地区, 对多 种生态系统和大量动植物的保护起到了至关重要的作用。经过多年的努力, 一些重要珍稀濒危 动物种群数量有所增加。但这些保护区仍然存在一系列问题, 主要包括三方面, 一是客观因 素, 大多数保护区地处边远落后山区二是来自于周边村寨巨大的人口压力三是来自于当地 政府和保护区, 主要是缺乏长远规划、大力投资等问题。保护区资源受到如此多种因素的威 胁, 保护效果得不到充分发挥。只有采取强有力的保护措施, 如加强社区共管、拓宽投资渠 道、进行科学规划管理等, 才能使保护区走上可持续发展的轨道。

进化中的选择原理

该文简要介绍了在过去几十年中非平衡统计物理研究有序现象的新概念及其在探讨进化问题中的应用和意义。

滇金丝猴(Rhinopithecus bieti)现状及其保护对策研究

滇金丝猴生活在海拔3800-4300m的原始冷杉林中, 但有时也会在4300-4700m的低矮灌丛、草甸和流石滩上活动达数小时之久, 甚至能跨越近千米的无林高海拔地带。松萝是它们的主要食物, 取食松萝的时间占总取食时间的91%。猴群活动范围可达近百平方公里。笔者在历时8年的野外考察中, 已查明这一物种的全部现存自然种群只有13个, 分布在云南的德钦、兰坪、潍西、丽江和西藏的芒康这五县境内, 其现存种群数量为1000-1500只; 所有现存自然种群几乎均处在相互隔离的状态, 群间已不可能进行基因交流, 充分表明它们已到达灭绝边缘。