Food-web traits of protected and exploited areas of the Adriatic Sea

This study presents a comparative analysis of protected and exploited Mediterranean Sea food webs using standardized ecological models of two ecosystems: the Central-North Adriatic Sea (highly exploited) and the Miramare Natural Marine Reserve (Northern Adriatic Sea, protected since 1986). Food webs are analysed in terms of structural and functional traits including trophic levels, transfer efficiency, trophic role of species and keystoneness, trophic spectra and other synthetic ecological indicators. Our results highlight similarities between food webs of the Adriatic Sea, differences that are likely due to the impact of fishing and differences that should be related to other factors. Analysis of biomass distribution along functional groups and of trophic spectra indicates that protected area presents higher mean trophic level of the community, higher biomasses, lower production and generally lower transfer efficiency than fished area. Our results indicate that measures of food web complexity (system omnivory index and ascendency), as well as pelagic/demersal and fish/invertebrates biomass ratios are higher in the protected area than in exploited ecosystem due to fishing-induced changes. Thus, this study highlights that marine protected areas can efficiently contribute to maintain structural and functional traits of marine ecosystems.     

小国光苹果贮藏保鲜紫外光、红光照射与钴辐射处理

选取小国光苹果分别做紫外光和红光照射及钴辐射3种物理处理后,进行保鲜贮藏试验。在贮藏期定期测定果实的呼吸强度和主要化学成分的变化,对测定数据作统计分析。结果表明,红光照射与钴辐射处理能显著地抑制苹果的呼吸强度,推迟苹果呼吸高峰的时间,起到贮藏保鲜作用。     

双移动边界二维非齐次线性热传导方程的混合问题

应用Fouricr方法求得双移动边界二维非齐次线性热传导方程涉及第三边值条件的一个混合问题的解。     

菊花品种的过氧化物酶同功酶分析

试验对40多个菊花品种进行过氧化物酶同功酶分析的结果表明:1、酶谱表达具品种特征.品种间酶谱的差异程度与品种性状的差异程度表现一致;而且同品种植株在同一生育期内,叶、茎器官的酶谱均表现稳定,也不因年份或栽培条件而变化.2、同品种不同器官、生育期酶谱具特异性,叶、茎、花三器官之间存在酶谱差异.而且均随生育期的进展,谱带增多,活性加强.其中叶、茎为适宜取样器官,适宜取样时期为含苞待放期或花完全开放期.     

计算机农业试验数据处理系统CAEDAS

CAEDAS是一个农业试验数据的计算机处理系统。包括数据预处理、数据分析和文件管理三部分。其主要特点是设计思想新颖、使用方法简便、输入输出规范、分析程序全面。文中通过实例说明了系统的使用方法。     

Ecosystem effects of invertebrate fisheries

Since the 1950s, invertebrate fisheries catches have rapidly expanded globally to more than 10 million tonnes annually, with twice as many target species, and are now significant contributors to global seafood provision, export, trade and local livelihoods. Invertebrates play important and diverse functional roles in marine ecosystems, yet the ecosystem effects of their exploitation are poorly understood. Using 12 ecosystem models distributed worldwide, we analysed the trade‐offs of various invertebrate fisheries and their ecosystem effects as well as ecological indicators. Although less recognized for their contributions to marine food webs, our results show that the magnitude of trophic impacts of invertebrates on other species of commercial and conservation interest is comparable with those of forage fish. Generally, cephalopods showed the strongest ecosystem effects and were characterized by a strong top‐down predatory role. Lobster, and to a lesser extent, crabs, shrimp and prawns, also showed strong ecosystem effects, but at lower trophic levels. Benthic invertebrates, including epifauna and infauna, also showed considerable ecosystem effects, but with strong bottom‐up characteristics. In contrast, urchins, bivalves, and gastropods showed generally lower ecosystem effects in our simulations. Invertebrates also strongly contributed to benthic–pelagic coupling, with exploitation of benthic invertebrates impacting pelagic fishes and vice versa. Finally, on average, invertebrates produced maximum sustainable yield at lower levels of depletion (~45%) than forage fish (~65%), highlighting the need for management targets that avoid negative consequences for target species and marine ecosystems as a whole.     

行列式元素的两个要素

本文指出行列式的元素有数值和下标(行标和列标)两个要素。行列式的许多定理实际上描述了行列式的值与两要素的关系。并指出:在一些定理的证明中,突出行列式元素的两个要素,可使证明思路清晰,简单明了,容易理解。     

植物离体培养物中鱼藤酮的分离与HPLC测定

毛鱼藤（Ｄｅｒｒｉｓ ｅｌｌｉｐｔｉｃａ （Ｒｏｘｂ．）Ｂｅｎｔｈ．）和西非灰毛豆（Ｔｅｐｈｒｏｓｉａ ｖｏｇｅｌｉｉ Ｈｏｏｋ．ｆ．）离体培养物经９：１ＣＨＣｌ３／ＭｅＯＨ溶剂提取,Ｃ－１８柱层析分离后,在室温条件下以６６：３４ＭｅＯＨ／Ｈ２Ｏ或４２：５８ＣＨ３ＣＮ／Ｈ２Ｏ为流动相,支样品进行反相柱ＨＰＬＣ分析。结果表明,毛鱼藤和西百灰毛豆的愈伤组织均能合成鱼藤酮,但含量相当低,分别为１７．４μｇ／ｇ,１．８μｇ／ｇ干重。经诱导生根分化的毛鱼藤愈伤组织鱼藤酮含量达１３６．２μｇ／ｇ干重,为愈伤组织含量的７．８倍。西非灰毛豆悬浮培养物的鱼藤酮含量虽比愈伤组织有很大提高,但还不及毛鱼藤愈伤组织含量。结果表明,植物的基因类型在次生代谢上起重要作用,同时离体组织或细胞的分化有助于鱼藤酮的生物合成。