三峡库区地方特有维管植物研究

三峡库区位于我国中亚热带北部 ,既是我国植物种类丰富的地区之一 ,又是我国第三纪古老植物的残遗分布中心之一。从中国特有属的分布来看 ,该区被认为是中国三大特有植物分布中心之一的“川东 -鄂西”的分布中心〔1〕。该区的特有植物是在长期的自然历史发展过程中形成的 ,它们的存在与分布在科研上具有重要价值 ,而且较多的种类又是重要的资源植物 ,在开发利用上亦至关重要。因此 ,作者根据近年来在三峡库区实地调查的结果 ,结合有关文献 ,对三峡库区的地方特有维管植物的种类及分布特点进行了分析与探讨 ,为有效地保护三峡库区特有植物资…     

下颌第三磨牙拔除中预防下唇麻木和舌麻木的方法探讨

目的:探讨下颌第三磨牙拔除导致下唇和舌麻木的有关因素。方法:按照三种分类标准进行分组。第一种分组:以不同年龄段分成两组。第二种分组:以下颌第三磨牙根尖与下颌神经管的关系分成三组。第三种分组:以不同拔牙方法分为三组。结果:1.下颌第三磨牙拔除后引起下唇麻木和舌麻木与年龄无明显关系。2.460例下颌第三磨牙拔除术后出现下唇麻木31例(占6.74%),其中第二组和第三组占26例(占5.65%),第一组和第二组分别与第三组相比具有统计学意义(P0.05);出现舌神经损伤17例(占3.70%),其中第二组和第三组占14例(占3.04%),第一组和第二组分别与第三组相比具有统计学意义(P0.05)。3.口腔全景片显示的66例下颌第三磨牙根尖与下颌神经管重叠中,CBCT显示根尖多位于下颌神经管舌侧,而跨于下颌神经管最少见。4.拔牙方法越复杂,引起下唇和舌麻木的几率就越大。结论:本组病例的方法评估对拟定合适的治疗方案和安全指导拔牙以降低下唇和舌麻木具有重要的临床意义。     

一个光子能量的非连续分布方程

在假设光子的波长是最小波长的整数倍的基础上,给出一个光子能量的非连续分布方程。从方程得到以下结果,光子的最大能量为1/4(J),光的最高频率为1/πh(Hz),光的最小波长为πhc(m)。我们认为光的最小波长就是Planck长度,也是超弦的长度。     

Comparison of methods for assessing the impact of different disturbances and nutrient conditions upon functional characteristics of grassland communities

Background and Aims

Predicting the response of plant communities to variation in resources and disturbance is still a challenge, because findings depend on how ecological gradients are characterized and how grassland functional composition is assessed. Focusing on leaf dry matter content (LDMC), the efficacy of different methods for evaluating the best response of plant communities to either environmental or disturbance change is examined.

Methods

Data were collected on 69 grasslands located at four sites in the Pyrenees and Massif Central. N-Ellenberg indices and plant nutrient content (Ni) were compared to assess fertility, and either LDMC (meas) measured or calculated from a trait database for which traits were measured under the same environmental conditions (db). Management regime (MR) was characterized in terms of categories (grazing, cutting) and plant height.

Key Results

LDMCdb was positively correlated to LDMCmeas, but depended significantly on site temperature. N-Ellenberg and Ni were significantly correlated, and there was a significant effect of MR and temperature. LDMC responded to fertility, MR and temperature. Replacing MR by plant height in an REML analysis reduced the uncertainty of the LDMC prediction. LDMC was correlated to plant height at community level, whereas the correlation was weak at species level. Differences in LDMC between plant communities under any of the management regimes were significantly correlated to the standing herbage mass.

Conclusion

The N-Ellenberg index is a better indicator of fertility than Ni which is short-term and environment-dependent. LDMC taken from a database allows plant trait variation due to species abundance (excluding variation due to trait plasticity in response to management) to be captured. So the former is better suited for assessing agricultural services that mainly depend on plant phenology and tissue composition. LDMC responded to defoliation regime in addition to fertility because plant height is roughly correlated with LDMC at plant community level.     

黑麂皖-浙分布中心种群的遗传多样性

本文基于黑麂线粒体控制区序列对皖浙分布中心的4个黑麂种群的遗传多样性和基因流进行了研究。结果显示:4个种群的33个个体中有14个变异位点,占分析序列长度的2·91 %,并由此定义了12个单倍型;遗传多样性检测结果显示4个种群中开化种群具有最高的遗传多样性,应予以优先保护;4个种群间尚存在着一定的基因流,但存在可能由于遗传漂变而产生分化的危险。从Tajima’s D和Fu and Li’s D值的估算结果来看,这4个黑麂种群相对于中性进化的歧异度并没有明显的偏离,具有较为稳定的种群结构(P>0·1),没有明显的证据显示这4个黑麂种群间存在很强的平衡选择。     

海南珍稀药用植物种类及其保护

介绍井分析了海南珍稀濒危药用植物的种类、濒危状况以及濒危原因,井提出资源保护的建议和措施。     

亚高寒草甸不同坡向植物光合生理和叶片形态差异

绿色植物叶片的功能性状能用来解释不同层次复杂的生态学过程,被认为对植物的生存、生长和繁殖具有重要的影响。该研究对甘南亚高寒草甸坡向梯度代表物种的叶片形态和光合特性进行测定,分析了各坡向的土壤因子,比较不同物种(矮嵩草、米口袋、蒲公英和金露梅)之间的性状差异,研究叶片光合及形态特征与土壤因子之间的相关性。结果表明:1)不同坡向的土壤因子有着显著差异,土壤含水量、土壤全磷、土壤全氮及有机碳含量总体表现为北坡南坡,而土壤温度及光照度则是南坡北坡。2)坡向上不同物种在比叶面积、净光合速率和叶δ~(13)C值等方面有着显著的差异,比如物种在北坡具有较高的比叶面积和叶片含水量,而物种在南坡具有较高的净光合速率、相对叶绿素、叶干物质量及δ~(13)C值。3)冗余分析结果显示,物种的叶片形态及光合特性与土壤因子之间都具有显著的相关关系,其中土壤含水量变化的响应最为敏感。该研究揭示了亚高寒草甸坡向梯度上植物物种在叶片功能性状上的显著分化,使得这些物种能在同一个草地群落中共存。     

Dual Functional Mesoporous Silicon Nanoparticles Enhance the Radiosensitivity of VPA in Glioblastoma

Radiotherapy is a critical strategy and standard adjuvant approach to glioblastoma treatment. One of the major challenges facing radiotherapy is to minimize radiation damage to normal tissue without compromising therapeutic effects on cancer cells. Various agents and numerous approaches have been developed to improve the therapeutic index of radiotherapy. Among them, radiosensitizers have attracted much attention because they selectively increase susceptibility of cancer cells to radiation and thus enhance biological effectiveness of radiotherapy. However, clinical translation of radiosensitizers has been severely limited by their potential toxicity to normal tissue. Recent advances in nanomedicine offer an opportunity to overcome this hindrance. In this study, a dual functional mesoporous silica nanoparticle (MSN) formulation of the valproic acid (VPA) radiosensitizer was developed, which specifically recognized folic acid–overexpressing cancer cells and released VPA conditionally in acidic turmeric microenvironment. The efficacy of this targeted and pH-responsive VPA nanocarrier was evaluated as compared to VPA treatment approach in two cell lines: rat glioma cells C6 and human glioma U87. Compared to VPA treatment, targeted VPA-MSNs not only potentiated the toxic effects of radiation and led to a higher rate of cell death but also enhanced inhibition on clonogenic assay. More interestingly, these effects were further accentuated by VPA-MSNs at low pH values. Western blot analysis showed that the effects were mediated via enhanced apoptosis-inducing effects. Our results suggest that the adjunctive use of VPA-MSNs may enhance the effectiveness of radiotherapy in glioma treatment by lowering the radiation doses required to kill cancer cells and thereby minimize collateral damage to healthy adjacent tissue.     

圣海伦斯火山和高山植被

 Mt. St. Helens is an active volcano on the western flank of the Cascade: range in the southwestern Washington State, USA. It is located at lat. 46˚00′—46˚30′N, long 121˚52′—122˚40′W.We had investigated the alpine vegetation at Pine Creek, Butte Camp on Mt. St. Helens for three times, totaling ten days during August and eptember of 1983.The volcano had erupted sending out much pyroclastic, pumice and lava, which devdstated the vegetation around the crater. They not only mechanically destroyed plants tissue, but also buried entirely or partly of the plants.The radiant heat from the volcanic eruption caused the melting of ice and snow, creating huge mudflows, which estroyed and buried vegetation. The high temperture from direct radiant heat incinerated and scorched all the plants. On the other hand, the higher the elevation is, the stronger the wind and the lower the temperture; also snow was present on the alpine range, and this provided a lee for plants, and consequently some plants survived, and new ones row out of the ground. The alpine vegetation on Mt. St. Helens bears both the characteristic of alpine plants and the brand of volcanic activities: vegetation is sparse, species composition of plants limited, structure of community simple, production low and vegetation propagation being the main type of vegetative reproduction.The different types of lpine vegetation grow in different habitats: The community of Luekea pectinata grow in places covered by ice and snow; the community of Polygonum newberryi, Eriogonum pyroleafolium in localities covered by mudflow; the community of Phyllodace empetriformis on slopes of steep rocks and the community of grasses and sedges on low hills and plains. Hese are the four main communities on Mt. St. Helens. The recovery and succession of the alpine vegetation has been discussed. There are two types of succession, the primary and the secodary, with the secondary being the main one.Finally, the paper has analysed the reason why no forest occurs, on Mt. St. Helens. We think that it is a result of the ctive period of the volcano and that the climate conditions are favouable for forest. Also, we have suggested that some herbaceous plants be sown as soon as possible for they can accelerate the recovery of vegetation, and prevent the runoff of soil and water.     

A comparison of two methods for evaluating drug-induced chromosome alterations.

Evaluating the technique and procedure for mutagenicity testing in mammals is a prerequisite to the development of a broad spectrum mutagenic assessment program. Two techniques, chromosome examination and micronucleus scoring, show promise but their applicability for mass screening is uncertain. We determined the slide observation time for these two techniques in mice treated orally, subcutaneously, intravenously, and intraperitoneally with cyclophosphamide (CY). In each instance, we detected a dose-response in less observation time by counting micronuclei in polychromatophilic erythrocytes. The simplicity of the scoring method, the ease of micronucleus identification and the rapidity of scoring all suggest the micronucleus test may be favorably integrated into a mutagenicity screening program.