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1.
宣化盆地辛庄子黑砂土剖面研究   总被引:1,自引:1,他引:0  
采用扫描电镜观察及理化分析技术,从辛庄子沙丘黑砂土剖面中提取出古气候信息,综合研究得出:在11000-8300aBP期间,本区经历了2个大的气候阶段,即1100-10000aBP的相对于早期和10000-8300aBP的相对湿润期,但润程度不及80000-6000aBP,这可与相邻地区同期的气候波动记录进行对比。  相似文献   

2.
将含完整阅读框架的人t-PA(tissue-ytpe plasminogen activator,t-PA)cDNA克隆至昆虫细胞表达转移载体pBacPAK8中,获得重组质粒pBac-tPA。应用脂质体共转染法,将pBac-tPA和线性化杆状病毒BacPAK6 DNA共转染Tn-5B-1昆虫细胞。经空斑筛选获得11株重组病毒。经PCR鉴定与生物活性测定,获得一株高效表达t-PA的重且病毒BactP  相似文献   

3.
用普通的电子陶瓷工艺制备了PbO-SrO-BaO-Nb2O5(PSBN)系统民陶瓷,研究了PSBN系统铁电陶瓷的介电性能与烧结温度的关系,XRD分析表明:PSBN系统铁电陶瓷的主晶相是Pb0.7Ba0.3Nb2O6(PBN)、Sr0.5Ba0.5Nb2O6(SBN)和Ba0.27Sr0.75Nb2O5.78(BSN),将这一复杂的化学系统看作三元系固熔体,其中PBN、SBN和BSN各相比例随烧结温  相似文献   

4.
控制细胞内游离〔Ca^2+〕用的七种螯合剂BAPTA衍生物已合成成功,其中对〔Ca^2+〕低亲和力的5,5’-二硝基BAPTA及中等亲和力的5,5‘-二溴BAPTA,5-溴-5’-甲基BAPTA已分别应用于控制不同体系的〔Ca^2+〕测定。本文详述它们的合成方法,性能及苯环上不同取代基对Ex、Em、Kd值影响的规律性。  相似文献   

5.
采用二甲基甲酰胺、水杨醛、氨基乙酸、乙酸改性的聚邻苯二胺膜电极(PODB)配合Ni(Ⅱ),形成PODBd-Ni(Ⅱ),PODBh-Ni(Ⅱ),PODBe-Ni(Ⅱ),PODBa-Ni(Ⅱ)电极。红外光谱显示,Ni(Ⅱ)是由于改性物质和PODB以酰胺的形式结合,从而引入更多的含孤对电子的元素,配合到PODB膜中去的。在HCl溶液中(pH=3),PODBa-Ni(Ⅱ)的配合稳定性最好。掺杂Ni的PODB对O2和抗坏血酸(H2A)有电催化还原和氧化的作用。对H2A的催化氧化属于平行催化机理,电极反应受H2A向电极表面扩散的控制。  相似文献   

6.
前期研究发现CaMBP-10参与植物细胞对生长素应答反应的调节,但调节机理有待阐明,本文表明CaMBP-10是由于影响质膜H-ATPase活性,进而影响了质子外泌和细胞伸长,并进一步证明,它对质膜H-ATPase活性的调节是通过介导该酶磷酸化而实现的最终调节了细胞对激素的应答。  相似文献   

7.
α-fuzzy子群   总被引:1,自引:1,他引:0  
给出了一种新型的fuzzy子群的定义,它是Rosenfeld的定久及S.K.Bhakat和P.Das定义的推广,我们还给出了α-fuzzy子群的等价定义,给出了正a-fuzzy子群的定义,研究了a-fuzzy商群及a-fuzzy子群的同态象性质。  相似文献   

8.
5000年来秦皇岛至成山角海岸新构造运动分析   总被引:2,自引:0,他引:2  
在列举全新世渤海海岸3100-3900aB.P和500-600aB.P.两期海平面遗迹资料的基础上,分析了沿海岸走向同期异地古少平面遗迹高度的变化规律,发现5000a来郯庐断裂的活动对古海平面遗迹分布高度变化的影响,从而讨论了渤海海岸带的新构造特征。  相似文献   

9.
中国全新世的环境演化   总被引:1,自引:1,他引:1  
全新世是地球历史中全新的一页,年龄为10×103年,测定全新世年龄的最佳方法为14C法,按照环境演化综合分析,全新世可以分为:前北方期(9300aBP以前)、北方期(7500-9300aBP)、大西洋期(5000-7500aBP)、亚北方期(2500-5000aBP)、亚大西洋期(2500aBP至现在).全新世环境的主要特征是:现代人使用的新石器不断革新;全球性的大冰盖已经消逝,只有一些高山冰川和极地冰川,所以称为冰后期;海平面有多次的缓慢升降,总的趋势是不断升高;现代地壳运动是三大板块继续移动,并有多次的地震和火山喷发期;构造地貌和气候地貌的三大地貌单元已经形成;现代人的出现是全新世环境演化的最基本特征。这些特征的相互作用,构成了全新世的环境演化。  相似文献   

10.
江苏龙虬庄新石器遗址环境考古研究   总被引:14,自引:0,他引:14  
龙虬庄新石器文化遗址被列为1993年中国十大考古发现之一。根据^14C测年、器物排比法断代、孢粉、粒度、氧化物和磁化率等鉴定分析,探讨了遗址区古生民生存的环境。分析表明,龙虬庄地区在经历新仙女木寒冷期之后迎来了全新世暖期环境,10000-7000aBP间气候进入适宜期,但当时湿润程度尚不及此后7000-6000aBP间的新石器时期,当时 冬春季节应当有较大的风沙沉积。6300aBP前后的气温可能更  相似文献   

11.
The results of sedimentary characteristics,grain-size,clay mineral,C/N and pollen analysis reveal the evolution history of the Shuangchi Maar Lake of Hainan Island as well as the short-term climate variations in tropical areas.It is testified that the Maar sediment system was sensitive in recording the rapid climate changes in the Holocene.These multidisciplinary results demonstrate that the thermal maximum in the Holocene climate lasted from 7200 to 2700 aBP,with serveral abrupt ephemeral vibrations occurring between 7250-6120aBP and at around 4460,3850 and 2700 aBP.In the late Holocent,particularly at -2700 aBP,a distinct environmental change indicating an important climate transition in the tropical eastern Asia was recorded,probably responding to the enhancement of ENSO phenomena in the Pacific Ocean.In addition,the high-resolution algae record clearly indicates periodical climate fluctuations at 500 a cyclicity during the last 2500 years.  相似文献   

12.
河南洛阳寺河南剖面中全新世以来的孢粉分析及环境变化   总被引:18,自引:0,他引:18  
对河南洛阳寺河南剖面进行的高分辨率的孢粉分析表明,该地区中全新世以来的孢粉组合以草本植物占绝对优势。其中以蒿属(Artemisia)最为丰富,其次为禾本科(Gramineae)和藜科(Chinopodiaceae)。乔木花粉含量较少,以松属(Pinus)为主。根据孢粉组合的变化,将剖面划分为5个孢粉组合带。早期(7.235~7.380 aBP)气候较为寒冷干燥,缺少乔木花粉。随着全新世大暖期的到来,在Ⅱ孢粉带上乔木花粉大量出现,种类丰富。尤其5.625~6.120 aBP期间出现了很多喜暖树种,是中全新世以来气候最好的时期。在4.580~5.625 aBP期间,乔木花粉急剧减少,表明气候发生恶化。随着气候的逐渐好转,乔木花粉在Ⅳ孢粉带(3.090~4.580 aBP)上重新出现,但喜暖树种较少。3.090 aBP以后出现较多的禾本科花粉,可能和该地区人类活动的增强相关。  相似文献   

13.
 通过对葫芦洞、三宝洞和董哥洞末次盛冰期(~30 000 aBP)以来的石笋氧同位素数据序列进行连续小波变换。其结果显示在中国南方区域冰期的气候波动较全新世剧烈,盛冰期的气候波动较冰消期剧烈。在全新世阶段,董哥洞和三宝洞石笋氧同位素的周期均具有显著的三阶段特征。但在千百年尺度上,两地气候周期的长度和强度并不尽相同,董哥洞石笋氧同位素的周期信号相对较弱。其原因是董哥洞区域受西南季风和东亚季风的共同影响,二者之间的反相位关系削弱和改变了气候变化的千年周期。这一特征反映了不同季风区域、不同周期的气候变化主导因素可能有所差异。分析结果同时显示,在~3 000 aBP,东亚区域气候模式可能发生了重大转折。  相似文献   

14.
The paleoclimate and paleoenvironment of Qinghai Lake indicated by a 16000-year pollen record are as follows. It was very cold and dry before 15200 years. During the Late Glacial, the climate varied from colder and semiarid to cool and semi-humid and fluctuated frequently but with little amplitude. Three cold events in the periods of 13400–13000, 11600–12000, and 11000–10400 aBP respectively correspond to the Oldest Dryas, Older Dryas and Younger Dryas events, whereas the two warm periods between them, 12000–13000 and 11600–11000 aBP, respectively correspond to Bölling and Alleröd periods. The temperature increased abruptly after the Younger Dryas event, and then the climate gradually turned to be warm and wet from warm and semiarid. In the Holocene, the largest amplitude of cold event that occurred at ca. 8200 aBP is quite prominent. The Holocene climatic optimum culminated at 6700 aBP. After 2100 aBP, the climate tended to be cold and dry, keeping on up to now. Palaeoclimatic evolution and events of Qinghai Lake based on pollen assemblage and concentrations can be well parallel with the global climatic events.  相似文献   

15.
Based on pollen records in B-3GC gravity core, environmental change since 9500 aBP of Okinawa Trough and its adjacent islands was derived. The result showed that the most time during this period was in a warm temperate climate except in middle Holocene (6800-4400 aBP) that was under subtropical climate control. During 9500–8300 aBP and 3100–2000 aBP periods, it appeared colder and drier than the rest time. The original area of pollen sources surrounding Okinawa Trough was covered by evergreen and deciduous broadleaf forest alternatively with mixed broad-leaf-conifer forest distributed in high mountainous areas. Usually, these three kinds of forests existed at the same time with difference in altitude. Pollen from subtropical and tropical plants increased obviously in about 5000–6000 aBP, reflecting a great lifting of vegetation zone and expansion of evergreen broad-leaf forest in the study area. However, there was a slight descending of plant zone and shrinking of evergreen broadleaf forest during 9500-8300 aBP and 3000-2000 aBP. During the remaining periods vegetation zone was higher than the present but in a limited range.  相似文献   

16.
Periodicity of Holocene climatic variations in the Huguangyan Maar Lake   总被引:7,自引:0,他引:7  
There exist five primary periods of 2 930, 1 140, 490, 250 and 220 a in the Holocene climatic variations in the Huguangyan Maar Lake, according to the energy-spectrum and filter analyses of high-resolution time sequences (10–15 a) of the sediment dry density. The peak values of the three temperature-decreasing periods with the 2 930 a cycle occur at about 7 300, 4 250 and 1 200 Cal. aBP. There are 7–8 temperature-decreasing periods with the 1 140 a cycle, and the climate fluctuation range is largest in the early Holocene, and reduces gradually in the middle and late Holocene. The millennial-scale climatic change in the Holocene may adjust the global water cycle and the thermohaline circulation intensity through the harmonic tones of the earth’s precession cycle, which in turn influences the global climate change.  相似文献   

17.
Through the use of reliable AMS dating of high resolution (15–30 years) peat and the establishment of monsoon climate proxies sequence, we have been able to recognize several cold, dry events in the Tibetan Plateau during the Holocene. The more obvious ones occurred around 12800, 11300, 10200, 9580, 8900, 6400, 4400, 3700, 2800 and 1500 cal. aBP. These events correlate well with both ice rafting events recorded in high latitude North Atlantic Ocean sediment cores and cooling events in the low latitude SST. Spectral analysis indicates high frequency climate variation on centennial-millennial time scale during the Holocene. This further reflects Holocene climate instability and the existence of centennial-millenium scale rhythm in mid latitude areas as well.  相似文献   

18.
Based on the analyses of Loss-on-Ignition (LOI), carbonate content and sediment characteristics, this paper reconstructs the climatic and environmental evolution of the Gahai Lake area since the late Last Deglacial Period.The results cover the late Last Deglacial Period and the Holocene.The climate was very unstable and rather arid during the late Last Deglacial Period.The Holocene can be divided into three pe-riods:the early Holocene (11360-8240 cal aB.P.), which was dry but unstable and featured rising tem-peratttres, the mid-Holocene (8240-3200 cal aB.P.), which was warm and wet and the late Holocene (since 3200 cal aBP), which was cold and dry.Results also show a warm-wet event around 1500 cal aB.P.  相似文献   

19.
Through the use of reliable AMS dating of high resolution (15-30 years) peat and the establishment of monsoon climate proxies sequence, we have been able to recognize several cold, dry events in the Tibetan Plateau during the Holocene. The more obvious ones occurred around 12800, 11300, 10200, 9580, 8900, 6400, 4400, 3700, 2800 and 1500 cal. aBP. These events correlate well with both ice rafting events recorded in high latitude North Atlantic Ocean sediment cores and cooling events in the low latitude SST. Spectral analysis indicates high frequency climate variation on centennial-millennial time scale during the Holocene. This further reflects Holocene climate instability and the existence of centennial-millenium scale rhythm in mid latitude areas as well.  相似文献   

20.
WesternChina,includingtheQinghaiXizangPlateau,theLoesplateau,andtheotherpartwestofthem(suchastheHexicoridorofGansuprovincean...  相似文献   

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