崇明东滩盐沼植被变化对滩涂湿地促淤消浪功能的影响

30年来在海平面上升、人类围垦、自然保护、外来物种入侵等自然与人为作用共同影响下,崇明东滩盐沼植被群落结构发生了巨大变化。基于长江口四期遥感影像解译结果,得到盐沼植被群落结构变化,结合对盐沼植被促淤消浪功能已有研究成果,量化崇明东滩盐沼植被促淤消浪功能潜力及其变化。研究表明:1980、1990、2000和2010年崇明东滩芦苇、互花米草、藨草群落面积比例分别为23∶0∶77、73∶0∶27、33∶9∶58、34∶34∶32,同期总植被覆盖面积分别为51、83、37、44 km2。30年来滩涂湿地促淤消浪能力均有下降,1990—2000年变化最大。其中,植被黏附悬浮颗粒物量分别为1976、4645、2192、4695 t;沉积量分别为960、1579、195、286万m3;常规波高情况下堤外没有足够植被保护的岸段长度分别为5、0、7、6 km;风暴潮情况下堤外没有足够植被保护的岸段长度分别为19、5、26、20 km。因此保护堤外盐沼植被对消浪促淤,特别是抵御风暴潮等恶劣气候灾害的影响具有重要意义。     

景观空间分析的特征和主要内容

在综合前人对景观空间格局与异质性,景观镶嵌动态,尺度,格局,过程相关等景观生态学基本原理的基础上,初步提出了景观空间分析的框架,认为景观空间分析主要包括景观空间形态分析,空间关系分析与空间构型分析,并对景观空间分析的特征及与一般空间分析之间的关系进行了探讨。     

Engineering the meso-Diaminopimelate Dehydrogenase from Symbiobacterium thermophilum by Site Saturation Mutagenesis for d-Phenylalanine Synthesis

In order to enlarge the substrate binding pocket of the meso-diaminopimelate dehydrogenase from Symbiobacterium thermophilum to accommodate larger 2-keto acids, four amino acid residues (Phe146, Thr171, Arg181, and His227) were targeted for site saturation mutagenesis. Among all mutants, the single mutant H227V had a specific activity of 2.39 ± 0.06 U · mg⁻¹, which was 35.1-fold enhancement over the wild-type enzyme.     

绞股蓝化学成分的研究

从广西金秀产绞股蓝提取的皂甙,经酸水解,硅胶柱层分离,得到5个甙元(1—5),利用化学反应和谱学分析方法鉴定,其中甙元1为人参二醇,甙元4为2α-羟基一人参二醇,甙元5为2α,19-二羟基-12-去氧人参二醇。甙元2和3的结构正在鉴定中。 关键词 绞股蓝;绞股蓝皂甙;人参二醇;2α-羟基人参二醇;2α,19-二羟基-12-去氧人参二醇     

空间直观景观模型LANDIS Ⅰ．运行机制

空间直观景观模型是指在异质景观中模拟景观尺度上生态过程的空间直观模型．LANDIS是一个用于模拟森林景观干扰、演替和管理的空间直观景观模型．通过在样地尺度上跟踪以10年为间隔的物种年龄级,半定量化地描述火和风倒,及使用位数组表示物种年龄结构,LANDIS能同时在物种、样地和景观尺度上模拟各种生态过程及其相互关系．详细论述了LANDIS模型对种子传播、火、风倒和砍伐等生态过程的模拟,并讨论了模型中存在的一些不足．     

Conversion of coastal wetlands,riparian wetlands,and peatlands increases greenhouse gas emissions: A global meta‐analysis

Land‐use/land‐cover change (LULCC) often results in degradation of natural wetlands and affects the dynamics of greenhouse gases (GHGs). However, the magnitude of changes in GHG emissions from wetlands undergoing various LULCC types remains unclear. We conducted a global meta‐analysis with a database of 209 sites to examine the effects of LULCC types of constructed wetlands (CWs), croplands (CLs), aquaculture ponds (APs), drained wetlands (DWs), and pastures (PASs) on the variability in CO₂, CH₄, and N₂O emissions from the natural coastal wetlands, riparian wetlands, and peatlands. Our results showed that the natural wetlands were net sinks of atmospheric CO₂ and net sources of CH₄ and N₂O, exhibiting the capacity to mitigate greenhouse effects due to negative comprehensive global warming potentials (GWPs; ?0.9 to ?8.7 t CO₂‐eq ha^?1 year^?1). Relative to the natural wetlands, all LULCC types (except CWs from coastal wetlands) decreased the net CO₂ uptake by 69.7%?456.6%, due to a higher increase in ecosystem respiration relative to slight changes in gross primary production. The CWs and APs significantly increased the CH₄ emissions compared to those of the coastal wetlands. All LULCC types associated with the riparian wetlands significantly decreased the CH₄ emissions. When the peatlands were converted to the PASs, the CH₄ emissions significantly increased. The CLs, as well as DWs from peatlands, significantly increased the N₂O emissions in the natural wetlands. As a result, all LULCC types (except PASs from riparian wetlands) led to remarkably higher GWPs by 65.4%?2,948.8%, compared to those of the natural wetlands. The variability in GHG fluxes with LULCC was mainly sensitive to changes in soil water content, water table, salinity, soil nitrogen content, soil pH, and bulk density. This study highlights the significant role of LULCC in increasing comprehensive GHG emissions from global natural wetlands, and our results are useful for improving future models and manipulative experiments.     

底栖类球蛛的核型分析（蜘蛛目：类球蛛科）

第1次报道底栖类球蛛的核型分析,包括染色体数目、形态结构和性染色体组成。实验结果表明底栖类球蛛的染色体数目是:雄性体细胞染色体数为2n=22,雌性体细胞为2n=24,性决定机制为X_1X_2O系统,X染色体为最小的和次最小的,5~＃染色体为随体染色体;对C-标本分析表明,染色体均为端或亚端着丝粒染色体,各染色体C-带带纹有识别特点。     

Psychometric properties of the Chinese version of the Perceived Stress Scale in policewomen

Background

The 10-item Perceived Stress Scale (PSS-10) is one of most widely used instruments to measure a global level of perceived stress in a range of clinical and research settings. This study was conducted to examine the psychometric properties of the Simplified Chinese version of the PSS-10 in policewomen.

Methodology

A total of 240 policewomen were recruited in this study. The Simplified Chinese versions of the PSS-10, the Beck Depression Inventory Revised (BDI-II), and the Beck Anxiety Inventory (BAI) were administered to all participants, and 36 of the participants were re-tested two weeks after the initial testing.

Principal Findings

The overall Cronbach''s alpha was 0.86, and the test–retest reliability coefficient was 0.68. Exploratory Factor Analysis (EFA) yielded 2 factors with eigenvalues of 4.76 and 1.48, accounting for 62.41% of variance. Factor 1 consisted of 6 items representing “negative feelings”; whereas Factor 2 consisted of 4 items representing “positive feelings”. The item loadings ranged from 0.72 to 0.83. The Confirmatory factor analysis (CFA) indicated a very good fit of this two-factor model to this sample. The PSS-10 significantly correlated with both BDI-II and BAI, indicating an acceptable concurrent validity.

Conclusions

The Simplified Chinese version of the PSS-10 demonstrated adequate psychometric properties for evaluating stress levels. The results support its use among the Chinese population.