A new species of Thais (Mollusca: Neogastropoda: Muricidae) with direct development from northwestern Australia

Thais wutingi, a new species of Muricidae, is described from rocky and mangrove shores in the vicinity of Darwin, northern Australia. It is relatively common where it occurs but the species may have previously been mistaken for T. gradata (Jonas) or T. javanica (Philippi). The new species differs from the latter two species in having a penis with a narrow groove along the greater curvature of the penial base. The larvae of T. wutingi undergo direct development, hatching from egg capsules as crawling juveniles, in contrast to the majority of Thais (s.l.) species found in the tropics which have planktotrophic development. Its mode of development may explain the relatively restricted geographical distribution of this species, which is confined to the north and northwestern coasts of Australia.     

河南省植物多样性研究

根据最新资料从植物的分类单位、地理成分、特有种类、珍稀濒危植物以及群落类型等方面论述了河南省野生植物的多样性,并从古生态环境和现代生态环境以及地理位置等方面分析了本省植物多样性形成的原因。     

带潜伏期和年龄结构流行病模型的稳定性

根据肺结核的传播特点,建立了带潜伏期和潜伏年龄的数学模型.证明了当基本再生数R0〈1时,系统无病平衡点是局部和全局渐近稳定的;当R0〉1时,无病平衡点不稳定,此时系统存在一个地方病平衡点,并证明了该地方病平衡点是局部渐近稳定的.     

山东维管植物特有种的生物多样性及其保护

论述了山东管植物特有种的物种组成多样性,生活型多样性和空间分布格局多样性及其生态地理特征和区系特征,并对特有种的生物多样性保护与持续利用提出了切实可行的对策。     

一类特殊流行病的动力模型和动力性状分析

针对类似乙肝的一类流行病的传播机制．建立较好的常微分动力模型．通过研究它的动力稳定性,得到较为理想的结论。     

Reptile distribution may identify terrestrial islands for conservation: the Levant’s ‘Arava Valley as a model

Widely accepted major criteria for biodiversity hotspots that deserve conservation include species richness, endemism and threat. Proving that a taxon is endemic to a given area is more difficult, and therefore expensive, with animals than with plants because of the difficulty to prove absence outside the known distribution. Seeking a cost-efficient practical method to show animal endemism while funds necessary for conventional demonstration of endemism are lacking, we argued that when the known distribution of a suspected endemic taxon coincides with an eco-geographically isolated area, e.g. island, its exclusivity to that area is more credible. We selected a model site containing suspected endemics, the ‘Arava depression (altitude - 400–0 m) between arid southern Israel and southern Jordan. A search of the literature and collections found at least 23 animal taxa endemic to the ‘Arava, to the adjacent Dead Sea basin sharing the depression, or to both. We assessed the level of isolation of the ‘Arava depression by statistically analysing the geographical distribution of taxa (species or subspecies) of one selected well researched model group, Squamata (lizards and snakes). In northern Israel and Jordan the squamate faunas of the two countries are very similar. In contrast in the south where the ‘Arava intervenes, the two faunas greatly differ. The ‘Arava both constitutes a partial barrier and is partly isolated. Hence its apparent endemics are likely real endemics, inviting conservation of the area. The more so since the ‘Arava is also an arena of much research and education. Our methodology may serve worldwide to identify semi-isolated terrestrial areas for conservation.     

具有年龄结构的SIRS流行病模型的分析

建立和研究一类具有非终身免疫并带有年龄结构的SIRS流行病模型平衡解的存在性与稳定性。在总人口规模不变的假设下,运用微分方程和积分方程的理论和方法得到了决定疾病消亡与否的基本再生数R0的表达式;证明了当R0<1时无病平衡点是全局渐近稳定的,当R0>1时此时至少存在一个地方病平衡点,并在一定的条件下证明了该地方病平衡点的局部渐近稳定性。     

中国荨麻科植物地理分布

结合文献资料研究和在各地开展荨麻科植物调查,对荨麻科植物的物种丰富度、特有性指数、相似性系数、垂直分布和水平分布进行数据处理,结果表明:该科植物的分布中心在滇、桂一带;特有性中心在台、滇、藏、桂等地;相似性系数较大是地理上相近、环境异质性较小的地区;垂直分布中心为500～2 000m;水平分布中心为东经90°～120°和北纬20°～35°.受地理环境、气候因素等影响,荨麻科植物主要分布在高原地区,平原、丘陵地区种植较少,且品种缺乏.     

慢性氟中毒对大鼠基础生长的影响及金属离子的拮抗作用

目的 通过动物实验,研究慢性氟中毒对大鼠生长的影响,以及钙、镁和铝离子对慢性氟中毒的拮抗作用,为研究地氟病的分子机制及其治疗提供基础数据.方法 断奶1周的24只雄性SD大鼠,随机分成4个实验组,分别为对照组、高氟组、氟＋镁＋铝拮抗组和氟＋钙拮抗组.全群饲喂3个月,每隔两天称量大鼠体质量、摄食量和饮水量.处死前3d,每天留取24 h尿液,测定尿氟含量.结果 1）与对照组相比,高氟组体质量增长速度明显减缓,加钙拮抗组体质量增长速度比对照组快,也比高氟组快;2）高氟组的尿氟含量高于其他组,加镁铝拮抗组和加钙拮抗组比高氟组低,但仍高于对照组;3）各组摄食量和饮水量无明显差异.结论 慢性氟中毒会减缓动物个体的生长速度,而在饮水中添加镁、铝或钙离子能够起到一定的拮抗作用,钙离子拮抗作用更为明显.     

特有濒危植物长柄双花木濒危原因及其保护对策

长柄双花木为我国特有二级重点保护濒危植物,主要分布于江西、湖南、浙江和广东等省的部分区域。本研究综合分析了长柄双花木的自然地理分布特征、群落学特征、生物学特性、繁殖生态学特征及其濒危的可能原因。导致长柄双花木濒危的原因主要有：（1）在有性生殖过程中,由于花粉和资源限制、花粉竞争、传粉昆虫缺乏以及有机养分积累不足等,导致其有性繁殖能力差,结实率和结籽率低。（2）自然条件下种子萌发困难,萌发率、成苗率。（3）克隆繁殖能力有限,自然种群中克隆个体稀少。（4）生境片段化导致种群缩小,更新困难。（5）严重人为干扰直接导致种群锐减。此外,本研究还从强化科学研究和和保护途径等方面探讨了其保护对策。