利用牡蛎壳粉制备缓释氮肥的初步研究

<正>目前我国化肥当季利用率中,氮约为30%～35%,磷为10%～25%,钾为35%～50%远低于世界发达国家水平[1],造成肥料利用率低的主要原因是淋溶损失,尤以氮肥、钾肥为最。人们正在努力寻求提高肥料利用率的方法,其中之一是对肥料本身进行改性,开发适合于作物生长需求的新型肥料[2]。研制缓/控释肥料是世界各国普遍采用的有效措施之一。缓释肥料的优点是利用率高,养分损失少,环境友好[3,4]。但是,目前所用的作为缓释材料的高分子聚合物一般是难降解或不能降解,长期施用也会引起土壤污染。牡蛎壳为一种新型的天然材料,具有无毒、无污染、无公害的优点。而且,能为土壤微生物提供钙源和氮源,改良土壤微生物的群落结构,并间接的提高土壤肥力,是一种极有前途的土壤改良和调理剂,特别适合作为大棚酸化土壤的     

全球经济一体化与土地可持续利用

全球经济一体化 及其主要表现 全球经济一体化过程是一个在全球统一市场战略下，国际经济布局重新调整中世界各国间经济联系和相互依赖日益加深，而民族性和地域性逐步减弱的过程。从这一过程的运行来看，具体表现在四个方面。 全球经济一体化中的 科技深化 ２０世纪百年科技发展史表明，科技创新是世界经济持续增长与全球扩展的不竭源泉和动力。从西方发达国家科学技术对经济增长的贡献率来看；２０世纪初为２０％左右，５０～６０年代为４０％～５０％，７０～８０年代为 ６０％～７０％，目前已达６０％～８０％。全球经济一体化是以发达…     

我国农业用水效率仅为发达国家一半左右

由于多年来采取传统的大水漫灌方式，目前我国农业用水的有效利用率仅为40％左右，远低于欧洲鲁发达国家70％至80％的水平。     

国内外铝市场分析及对我省铝土矿经济政策的建议

铝工业是我国实现工业新型化与农业现代化及城镇化，进而实现全面建设小康社会目标的重要基础产业。它在我国产业中有很高的关联度，我国现有产业124个，使用铝产品的产业达113个，产业关联度为91％；铝产品消费量同我国GDP的线性相关系数高达0．933；它是我国总资产贡献率最高的产业之一，全国工业及有色金属工业总资产贡献率分别为9％与7～8％，全国铝工业总资产贡献率达10％以上。     

广西唯一一家“注册电子贸易师认证考试中心”常年招生

根据WTO预测，2005年通过网络的国际贸易占到世界贸易总额的10％～15％。于此同时据CNNIC统计，目前我国有40％多的网民在一年之内有上网购物活动，2005年网上商品销售总额达218．56亿元。2006年4月1日《中华人民共和国电子签名法》的正式实施。明确规定了电子签名、数据电文具有同等法律效力。在客观上推动了电子商务的发展。2006年1月8日，国务院办公厅颁发第2号文件，即《关于加快电子商务发展的若干意见》，该意见指出，发展电子商务是以信息化带动工业化，转变经济增长方式，提高国民经济运行质量和效率，走新型工业化道路的重大举措。     

沸石深加工制取肥料增效剂

沸石经深加工、处理制取肥料增效剂，对于提高氮肥、尿素利用率有独特功效。经小面积多品种作物农田应用，大面积多品种肥料混施试验，获得成功。具有少投入、多产出、工艺简便的特点。     

黑斑口虾蛄生态因子的试验观察

选用活力强、体长10cm左右的黑斑口虾蛄，进行海水盐度、水温、pH值等生态因子试验。结果表明：其生存的海水盐度为6．02％～38．64％，适宜的盐度是24．20‰～29．51‰；生存的水温为10～35℃，适宜的水温为22～30℃；存活的PH6～10，适宜的PH7～9。主要以摄食贝类、鱼类及虾类为生。     

伊朗油气资源及相关政策法规

伊朗是世界主要石油生产国和出口国之一,是欧佩克(OPEC)第二大石油输出国。石油开采业是最重要的工业。石油出口收入占外汇总收入的80％,占政府预算收入的40％-50％,占国内生产总值的10％～20％。截止2001年底石油剩余探明储量为897亿桶,居世界第五位,占世界储量的8.5％,占中东地区13.1％。天然气剩余探明储量23万亿立方米,居世界第二位,占世界储量的14.8％,占中东地区41.1％。此外,还有丰富的铜、铬、铅、锌、铁、锰、硼、重晶石、大理石和煤等矿产资源。     

实行生态移民改善生态环境--关于整合扶贫与生态整治的战略思考

经过几十年，特别是20世纪90年代扶贫攻坚计划实施，我国扶贫工作取得了巨大成就，但目前我国还有约3000万贫困人口，这些人口主要聚集在生态环境恶劣地区。事实上，以往正是由于这些地区人口活动造成毁林开荒，过度垦牧，严重恶化了生态环境。目前，我国已成为世界上水土流失最严重的国家之一，水土流失面积已达367万平方公里，约占国土面积的38％，并以每年1万平方公里的速度在增加。西北黄土高原是我国水土流失最严重的地区，长江流域也面对巨大的生态隐患。我国还是世界上沙漠化危害严重的国家之一。     

一种柴油机热力循环（yong）平衡计算法

针对柴油机热力循环的特点，提出了一种柴油机（yong）平衡计算方法．该方法可以计算出工质与冷却介质之间由于温差传热而引起的煳损失。计算结果表明，减少排气损失和工质与冷却水的温差传热损失、改善燃料燃烧过程是提高内燃机可用能利用率的主要途径。     

Studies on the effects of polyaspartate protease fertilizer enhancer in the absorptions of soil nutrition and the enzymatic activities of crops

1　Introduction　Chinaisboththelargestproducerandthelargestconsumerofchemicalfertilizersintheworld .Since1984 ,Chineseconsumptionofchemicalfertilizerhasincreasedmorethanonetimes ,fromabout 17millionmetrictonsto 35millionmetrictons .However ,dur ingthesameperiod ,theyieldoffoodproductionhasincreasedonlyabout 10 % .Thediscrepancybetweenfertilizerconsumptionandyieldincreasehasindicatedthedrasticdecreaseofthebenefitsofchemicalfertiliz ers .Infact ,theutilizationefficiencyofnitrogenfer tilizerinC…     

A comparative study of intensive Litopenaeus vannamei culture on four bottom substrates without water change

The effect of four bottom substrates, oyster shell powder (OP), sugarcane bagasse (SB), a mixture of OP and SB (OS) and fresh soil (FS), on the water quality and bacterial and zooplankton density of intensive shrimp (Litopenaeus vannamei) culture tanks without water change and the growth performance of cultured shrimp were compared in this study. At the end of a 110 days culturing trial, the total ammonium-N (TAN) of the water on SB and the nitrite nitrogen (NO₂-N) on OS was significantly lower than that on the other substrates (P<0.05), which coincided with the high density of ammonium- and nitrite-oxidizing bacteria in the water on SB and OS, respectively. The concentration of chlorophyll a (Chl a) increased slowly on OP, SB and OS but remained low on FS. The density of total bacteria on OP, SB and OS was one order of magnitude higher than that on FS, and the density of zooplankton on SB and OS was significantly higher than that on FS or OP (P<0.05). The improved water quality and increased density of bacteria and zooplankton on SB and OS may have had a synergistic effect on shrimp culture, improving its growth performance (high survival rate and yield and low feed conversion rate). SB and OS were more effective for improving the growth performance of intensively cultured L. vannamei without water change than OP and FS. To our knowledge, this study presents the first evidence regarding the effect of different bottom substrates on intensive shrimp culture.     

The potential of ocean acidification on suppressing larval development in the Pacific oyster Crassostrea gigas and blood cockle Area inflata Reeve

We evaluated the effect of pH on larval development in larval Pacific oyster(Crassostrea gigas) and blood cockle(Arca inflata Reeve).The larvae were reared at pH 8.2(control),7.9,7.6,or 7.3beginning 30 min or 24 h post fertilization.Exposure to lower pH during early embryonic development inhibited larval shell formation in both species.Compared with the control,larvae took longer to reach the D-veliger stage when reared under pH 7.6 and 7.3.Exposure to lower pH immediately after fertilization resulted in significantly delayed shell formation in the Pacific oyster larvae at pH 7.3 and blood cockle larvae at pH 7.6 and 7.3.However,when exposure was delayed until 24 h post fertilization,shell formation was only inhibited in blood cockle larvae reared at pH 7.3.Thus,the early embryonic stages were more sensitive to acidified conditions.Our results suggest that ocean acidification will have an adverse effect on embryonic development in bivalves.Although the effects appear subtle,they may accumulate and lead to subsequent issues during later larval development.     

The potential of ocean acidification on suppressing larval development in the Pacific oyster Crassostrea gigas and blood cockle Arca inflata Reeve

We evaluated the effect of pH on larval development in larval Pacific oyster （Crassostrea gigas） and blood cockle （Arca inflata Reeve）. The larvae were reared at pH 8.2 （control）, 7.9, 7.6, or 7.3 beginning 30 min or 24 h post fertilization. Exposure to lower pH during early embryonic development inhibited larval shell formation in both species. Compared with the control, larvae took longer to reach the D-veliger stage when reared under pH 7.6 and 7.3. Exposure to lower pH immediately after fertilization resulted in significantly delayed shell formation in the Pacific oyster larvae at pH 7.3 and blood cockle larvae at pH 7.6 and 7.3. However, when exposure was delayed until 24 h post fertilization, shell formation was only inhibited in blood cockle larvae reared at pH 7.3. Thus, the early embryonic stages were more sensitive to acidified conditions. Our results suggest that ocean acidification will have an adverse effect on embryonic development in bivalves. Although the effects appear subtle, they may accumulate and lead to subsequent issues during later larval development.     

Immune functional impacts of oyster peptide-based enteral nutrition formula (OPENF) on mice: a pilot study

Oyster peptides were produced from Crassostrea hongkongensis and used as a new protein source for the preparation of an oyster peptide-based enteral nutrition formula (OPENF). Reserpine-induced malabsorption mice and cyclophosphamide-induced immunosuppression mice were used in this study. OPENF powder is light yellow green and has a protein-fat-carbohydrate ratio of 16:9:75 with good solubility in water. A pilot study investigating immune functional impacts of the OPENF on mice show that the OPENF enhanced spleen lymphocyte proliferation and the activity of natural killer (NK) cells in BALB/c mice. Furthermore, OPENF can improve intestinal absorption, increase food utilization ratio, and maintain the normal physiological function of mice. These results suggest that oyster peptides could serve as a new protein source for use in enteral nutrition formula, but more importantly, also indicate that OPENF has an immunostimulating effect in mice.     

马氏珠母贝选系F_2早期选择反应和现实遗传力估计

对马氏珠母贝基础群体进行持续选择建立选系F2,比较了选系F2与对照群体早期生长差别,并估计了选择反应和现实遗传力。结果表明,在第8、14、21和35天,选系F2的平均壳长显著大于对照群体(P<0.05)。在第8、14、21和35天,选择反应和现实遗传力变化范围分别为0.63～0.89和0.36～0.51。本研究表明利用群体选择可以明显改良马氏珠母贝养殖群体的生长性状。     

Effects of an artificial oyster shell reef on macrobenthic communities in Rongcheng Bay,East China

An artificial oyster shell reef was deployed in Rongcheng Bay, East China. However, the effects of this reef on the surrounding macrobenthic communities were unknown. We compared sedimentary factors, macrobenthic biomass, abundance, and community composition and ecological indicators between the reef and non-reef areas over a one year period. The mean values for chlorophyll a （Chl a）, total organic matter （TOM）, total organic carbon （TOC）, and total nitrogen （TN） content in surface sediments in the reef area were slightly higher than those in the non-reef area. The Chl a levels differed significantly between the two areas, but the TOM, TOC, and TN were not significantly different. The abundance of crustaceans was significantly different between the two areas, but the abundance and biomass ofpolychaetes, echinoderms, mollusk did not differ significantly. The permutational multivariate analysis of variance （PERMANOVA） revealed that the macrobenthic community differed significantly through time and analysis of similarity multivariate analyses （ANOSIM） revealed that the macrobenthic community differed significantly in some months. The ecological indicators revealed that the environmental quality of the reef area was slightly better than that of the non-reef area. Overall, our results suggest that the artificial oyster shell reef may change the macrobenthic community and the quality of the environment. Despite the lack of an effect in the short term, long-term monitoring is still needed to evaluate the effects of artificial oyster shell reefs on macrobenthic communities.     

A new identification method for five species of oysters in genus Crassostrea from China based on high-resolution melting analysis

The high phenotypic plasticity in the shell of oysters presents a challenge during taxonomic and phylogenetie studies of these economically important bivalves. However, because DNA can exhibit marked differences among morphologically similar species, DNA barcoding offers a potential means for oyster identification. We analyzed the complete sequences of the cytochrome oxidase subunit I （COI） of five common Crassostrea species in China （including Hong Kong oyster C. hongkongensis, Jinjiang oyster C. ariakensis, Portuguese oyster C. angulata, Kumamoto oyster C. sikamea, and Pacific oyster C. gigas） and screened for distinct fragments. Using these distinct fragments on a high-resolution melting analysis platform, we developed an identification method that does not rely on species-specific PCR or fragment length polymorphism and is efficient, reliable, and easy to visualize. Using a single pair of primers （Oyster- COI-1）, we were able to successfully distinguish among the five oyster species. This new method provides a simple and powerful tool for the identification of oyster species.