排序方式: 共有29条查询结果,搜索用时 15 毫秒
1.
2.
从微泡菌属AG1(Microbulbifer sp. AG1)克隆得到1302 bp大小的琼胶酶基因,该基因编码产物为一个成熟蛋白(413个氨基酸残基)外加一个信号肽(20个残基)。将不含信号肽片段的琼胶酶在E. coli BL21 (DE3)中进行了异源表达和纯化。使用琼脂糖作为底物,该重组琼胶酶的最适反应温度和pH分别为60℃和7.5。该重组酶表现出优良的热稳定性,在50℃和60℃下处理1 h,重组琼胶酶仍能分别保持67%和19%的残余酶活力。除了SDS,重组琼胶酶对于其他测试的抑制剂、去垢剂和尿素变性剂有着较好的抗性。利用薄层色谱和以对硝基苯-α/β-D-吡喃半乳糖苷为底物的酶活力分析结果表明,该重组琼胶酶为β型琼胶酶,它水解琼脂糖的主要终产物为新琼四糖,而且不同聚合度的酶解产物具有抗氧化活性。 相似文献
3.
Extreme Enrichment of Tellurium in Deep-Sea Sediments 总被引:2,自引:0,他引:2
LI Yanhe WANG Yimin SONG Hebin and YUE Guoliang Laboratory of Isotope Geology Ministry of Land Resources Beijing E-mail: lyh@mx.cei.gov.cn Institute of Mineral Resources Chinese Academy of Geological Sciences Beijing National Geoanalysis Center Beijing 《《地质学报》英文版》2005,79(4):547-551
Tellurium is a sort of scattered rare element on the earth. Its concentration is very low in earth's crust, only 1.0 ng/g. However, it has extremely high abundance in Co-rich crusts, marine polymetallic nodules, deep-sea sediments and aerolites. To find out the origin of tellurium enrichment in deep-sea sediments, we analyzed and compared tellurium concentrations and helium isotope compositions in the magnetic parts and those in the bulk parts of deep-sea sediments. The result indicates that the helium content, 3He/4He ratio and tellurium concentration are obviously higher in the magnetic parts than those in the bulk parts. The 3He abundance varies synchronously with the tellurium concentration. 3He and Te have a distinct positive correlation with each other. It is the first time that the paper brings forward that the extreme enrichment of tellurium in deep-sea sediments, like helium isotope anomalies, probably results from the input of interplanetary dust particles (IDPs). Similarly, the extreme enrichment of tellurium in marine polymetallic nodules and Co-rich crusts is possibly related to IDPs. 相似文献
4.
5.
A watershed-based adaptive knowledge system for developing ecosystem stakeholder partnerships 总被引:1,自引:0,他引:1
This study proposes a Watershed-based Adaptive Knowledge System(WAKES) to consistently coordinate multiple stakeholders in developing sustainable partnerships for ecosystem management.WAKES is extended from the institutional mechanism of Payments for Improving Ecosystem Services at the Watershed-scale(PIES-W).PIES-W is designed relating to the governance of ecosystem services flows focused on a lake as a resource stock connecting its inflowing and outflowing rivers within its watershed.It explicitly realizes the values of conservation services provided by private land managers and incorporates their activities into the public organizing framework for ecosystem management.It implicitly extends the "upstream-to-downstream" organizing perspective to a broader vision of viewing the ecosystems as comprised of both "watershed landscapes" and "marine landscapes".Extended from PIES-W,WAKES specifies two corresponding feedback:Framework I and II.Framework I is a relationship matrix comprised of three input-output structures of primary governance factors intersecting three subsystems of a watershed with regard to ecosystem services and human stakeholders.Framework II is the Stakeholder-and-Information structure channeling five types of information among four stakeholder groups in order to enable the feedbacks mechanism of Framework I.WAKES identifies the rationales behind three fundamental information transformations,illustrated with the Transboundary Diagnostic Analysis and the Strategic Action Program of the Bermejo River Binational Basin.These include(1) translating scientific knowledge into public information within the Function-and-Service structure corresponding to the ecological subsystem,(2) incorporating public perceptions into political will within the Serviceand-Value structure corresponding to the economic subsystem,and(3) integrating scientific knowledge,public perceptions and political will into management options within the Value-and-Stakeholder structure corresponding to the social subsystem.This study seeks to share a vision of social adaptation for a global sustainable future through developing a network to adopt contributions from and forming partnerships among all ecosystem stakeholders. 相似文献
6.
河北平原地下水氦氩同位素特征 总被引:1,自引:1,他引:1
通过对河北平原地下水氦同位素进行分析比较,根据过剩He(4He exc)、3He/4He比值、δ3He和36Ar/38Ar及40Ar/36Ar值分析认为,河北平源地下水氦氩同位素有7个特征;①地下水中过剩He浓度沿地下水的流向而增高;②地下水中过剩He浓度随着地下水埋深加大而增高;③满城-沧州剖面上过剩He浓度大于石家庄-衡水剖面上的过剩He浓度;④河北平原地下水主要是由大气隆重水补给的;⑤衡水热水过剩He浓度很高(>674.83×10-8cm3STPg-1水);⑥地下水的36Ar/38Ar比值平均值为5.37,非常接近地球大气的比值(5.35);⑦地下水的40Ar/36Ar比值从296-412,均比大气氩的40Ar/36Ar比值(295.6)大,这表明40Ar都是放射成因的,且具有“年代积累效应”。 相似文献
7.
SHI Hebin ZHONG Hong LIU Yu DENG Jinyang 《《地质学报》英文版》2007,81(3):517-522
This article reports a preliminary research on silicate-incorporated hydroxyapatite as a new environmental mineral used to remove cadmium ions from aqueous solutions. The silicate-incorporated hydroxyapatite was prepared by coprecipitation and calcining, and silicate was incorporated into the crystal lattice of hydroxyapatite by partial substitution of phosphate. The amount of cadmium ions removed by silicate-incorporated hydroxyapatite was significantly elevated, which was 76% higher than that of pure hydroxyapatite. But the sorption behavior of cadmium ions on silicate-incorporated hydroxyapatite was similar to that of pure hydroxyapatite. Morphological study revealed that silicate incorporation confined the crystal growth and increased the specific surface area of hydroxyapatite, which were in favor of enhancing the cadmium ion sorption capacity of the samples. Incorporation of silicate into hydroxyapatite seems to be an effective approach to improve the environmental property of hydroxyapatite on removal of aqueous cadmium ions. 相似文献
8.
An agarase gene containing 1 302 bp was cloned from Microbulbifer sp. AG1. It encoded a mature protein of 413 amino acids plus a 20-residue signal peptide. The recombinant enzyme without the signal peptide was expressed and purified from Escherichia coli BL21(DE3). When agarose was used as a substrate, the optimal temperature and pH for the enzyme were 60℃ and 7.5, respectively. The recombinant agarase showed excellent thermostability with 67% and 19% of residual activities after incubation at 50℃ and 60℃ for 1 h, respectively.Except SDS, the recombinant agarase had a relatively good resistance against the detected inhibitors, detergents and urea denaturant. Thin layer chromatography analysis and enzyme assay using p-nitrophenyl-α/β-Dgalactopyranoside revealed that the recombinant agarase was a β-agarase that degraded agarose into neoagarotetraose as the main end product. The enzymatic hydrolysis products with different degree of polymerization exhibited the antioxidant activities. 相似文献
9.
ZHU Yanbing LI Hebin ZHANG Xuqin ZHANG Chunyan XIANG Jionghu LIU Guangming 《海洋学报(英文版)》2011,30(6):95-103
A thermostable superoxide dismutase (SOD) from the inshore thermophile Thermus sp. JM1 was purified to homogeneity by steps of fractional ammonium sulfate precipitation, DEAE-Sepharose chromatography and Phenyl-Sepharose chromatography. The specific activity of the purified native enzyme was 1 656 U/mg. A sod gene from this strain was cloned and overexpressed in Escherichia coli (E. coli). The prepared apo-enzyme of the purified recombinant SOD (rSOD) was reconstituted with either Fe or Mn by means of incubation with appropriate metal salts. As a result, only Mn 2+ - reconstituted rSOD (Mn-rSOD) exhibited the specific activity of 1 598 U/mg. SOD from Thermus sp. JM1 was Mn-SOD, judging by the specific activities analysis of Fe or Mn reconstituted rSODs and the insensitivity of the native SOD to both cyanide and H 2 O 2 . Both the native SOD and Mn- rSOD were determined to be homotetramers with monomeric molecular mass of 26 kDa and 27.5 kDa, respectively. They had high thermostability at 50 ° C and 60 ° C, and showed striking stability across a wide pH span from 4.0 to 11.0. 相似文献
10.