一论文集的一般P-C矩阵由论文数据和引文数据两部分组成。基于一般P-C矩阵并引入“等时性”概念，我们创建了关键变量Ck。Ck表示的是不同年份发表的论文在各自发表后第k年的引文数量的平均值。借助Ck可以构建R族科学发展节律指标，定义...一论文集的一般P-C矩阵由论文数据和引文数据两部分组成。基于一般P-C矩阵并引入“等时性”概念，我们创建了关键变量Ck。Ck表示的是不同年份发表的论文在各自发表后第k年的引文数量的平均值。借助Ck可以构建R族科学发展节律指标，定义为引文观察值和引文期望值的比值，用于反映科学发展的节律。R族指标包括4项指标：①指标R——被引年视角加三角形引文窗口；②指标R’——被引年视角加平行四边形引文窗口；③指标r——引用年视角加三角形引文窗121；④指标r’——引用年视角加平行四边形引文窗口。以Journal of Documentation为例，本文具体说明了R族序列的计算和R族指标的应用。展开更多
We describe an approach to studying the center problem and local bifurcations of critical periods at infinity for a class of differential systems. We then solve the problem and investigate the bifurcations for a class...We describe an approach to studying the center problem and local bifurcations of critical periods at infinity for a class of differential systems. We then solve the problem and investigate the bifurcations for a class of rational differential systems with a cubic polynomial as its numerator.展开更多
In this paper, we discuss the complex isochronicity of a sixth degree polynomial system. We first adopt a new algorithm to find necessary conditions for complex isochronicity, then prove the sufficient conditions usin...In this paper, we discuss the complex isochronicity of a sixth degree polynomial system. We first adopt a new algorithm to find necessary conditions for complex isochronicity, then prove the sufficient conditions using effective methods.展开更多
In this paper, we study the appearance of limit cycles from the equator and isochronicity of infinity in polynomial vector fields with no singular points at infinity. We give a recursive formula to compute the singula...In this paper, we study the appearance of limit cycles from the equator and isochronicity of infinity in polynomial vector fields with no singular points at infinity. We give a recursive formula to compute the singular point quantities of a class of cubic polynomial systems, which is used to calculate the first seven singular point quantities. Further, we prove that such a cubic vector field can have maximal seven limit cycles in the neighborhood of infinity. We actually and construct a system that has seven limit cycles. The positions of these limit cycles can be given exactly without constructing the Poincare cycle fields. The technique employed in this work is essentially different from the previously widely used ones. Finally, the isochronous center conditions at infinity are given.展开更多
Here we report the first direct Rb-Sr dating of pyrites and ores using sub-sampling from lode gold deposits in Linglong, Jiaodong Peninsula, which is a supra-large lode gold deposit and propose this as a useful geochr...Here we report the first direct Rb-Sr dating of pyrites and ores using sub-sampling from lode gold deposits in Linglong, Jiaodong Peninsula, which is a supra-large lode gold deposit and propose this as a useful geochronological technique for gold mineralization with poor age constraint. The Rb-Sr data of pyrites yield an isochron age of (121.6±8.1) Ma, whereas those of ore and ore-pyrite spread in two ranges from 120.0 to 121.8 Ma and from 110.0 to 111.7 Ma. Studies of characteristic of gold deposit and microscopy of pyrite and quartz indicate that the apparent ages of ore and ore-pyrite are not isochron ages, only mixed by two end members, i.e. the primitive hydrothermal fluids and wall rocks, whereas the isochron age of pyrite sub-samples constrains the age of gold mineralization (121.6±8.1) Ma, i.e. early Cretaceous, which is in good agreement with the published SHRIMP zircon U-Pb ages.展开更多
We report a combined internal and whole-rock Sm-Nd isochron age, and Nd and Pb isotopic data for gabbro dikes of the Luobusha ophiolite in Tibet. The Sm-Nd isochron of data for two whole rocks and plagioclase and clin...We report a combined internal and whole-rock Sm-Nd isochron age, and Nd and Pb isotopic data for gabbro dikes of the Luobusha ophiolite in Tibet. The Sm-Nd isochron of data for two whole rocks and plagioclase and clinopyroxene separates from one of the rocks yields a Middle Jurassic age of (177±31) Ma (with an initial εNd(t) = +8), which provides a significant bound on the time of formation of the Luobusha ophiolite. The Nd and Pb isotopic charac-teristics of the dike indicate an Indian-Ocean-type isotopic affinity, and we conclude that the Luobusha ophiolite formed in an oceanic setting during the Middle Jurassic.展开更多
The REE patterns of the basic volcanic rocks in Mangya area, Altun, are slight rich in LREE with (La/Ya)-N=1.69-3.20, (La/Sm)-N=1.37-1.87, other trace element ratios of the rocks are Th/Ta≈1 (for a few samples greate...The REE patterns of the basic volcanic rocks in Mangya area, Altun, are slight rich in LREE with (La/Ya)-N=1.69-3.20, (La/Sm)-N=1.37-1.87, other trace element ratios of the rocks are Th/Ta≈1 (for a few samples greater than 1.5), Nb/Y=0.34-0.62, Ti/Y=310-443 (on the average: 381), Ti/V=37-62, Zr/Nb=9.4-12.4, Sr/Rb=12-80 (on the average: 37), and Nb/Th=7.7-16.8. These features are similar to that of E-MORE or OIB. The ε Nd(t) value, being 3.95- 4.12, shows that the source of the volcanic rocks is derived from depleted asthenosphere mantle mixed with materials from enriched mantle. These, together with the information of geological setting and rock assemblages, indicate that the basic volcanic rocks are of ophiolite. The Sm-Nd isotope ages for the eight basic volcanic rock samples construct a straight line with good correlation, and the calculated isochron age is (481.3±53) Ma. Besides, the eight calculated ε Nd(t) and model ages are close to each other, which suggests that they are homologous, so the isochron is not a mixed line. In the meantime, the isochron age ((481.3±53) Ma) is lower than the model ages (T DM=1 004-1 534 Ma) of the samples, suggeting that the isochron age represents the formation age of the basic volcanic rocks and the ophiolite belt in Mangya area, Altun is formed in the early Paleozoic (Cambrian-Ordovician). In spite of the greater uncertainty of the age, it is still reliable because it is consistent with the age constrained by the regional strata.展开更多
The Pengjiakuang, Dazhuangzi and Fayunkuang gold deposits, located on the northern margin of the Mesozoic Jiaolai Basin, east of Shandong Province, are controlled by a low-angle normal fault. Gold ores are typically b...The Pengjiakuang, Dazhuangzi and Fayunkuang gold deposits, located on the northern margin of the Mesozoic Jiaolai Basin, east of Shandong Province, are controlled by a low-angle normal fault. Gold ores are typically brecciated, veinlet and disseminated. The Ar-Ar and Rb-Sr isochron dating methods were adopted to date ores and lamprophyre dike. The results indicate that the age of the Pengjiakuang gold deposit is 117.33—118.42 Ma, that of the Dazhuangzi gold deposit is 117.39 Ma, and that of the Fayunkuang gold deposit is (128.49±7.2) Ma. The consistency in metallogenic age between the gold deposits on the margin of the Jiaolai Basin and the gold deposits (115—126 Ma) of the northern uplift area suggests that both were formed in the same metallogenic period. That is to say, the large-scale metallogeny of the Jiaodong region took place in late-Yanshannian ((120±10) Ma).展开更多
Geologists have been paying much attention to the characteristics and age of the basement of the Tarim Block. Recently, some isotopic ages for the Precambrian rocks in the margin areas of the Tarim Block have been obt...Geologists have been paying much attention to the characteristics and age of the basement of the Tarim Block. Recently, some isotopic ages for the Precambrian rocks in the margin areas of the Tarim Block have been obtained. The oldest age presented by the above study is 2487±5.1 Ma determined with evaporated Pb-isotope method for zircons of the blue quartz-bearing granite from the Kuruktag area. However, the possibility of the Archaean basement of Tarim Block was only deduced. In this study the age of 3.3 Ga展开更多
文摘一论文集的一般P-C矩阵由论文数据和引文数据两部分组成。基于一般P-C矩阵并引入“等时性”概念，我们创建了关键变量Ck。Ck表示的是不同年份发表的论文在各自发表后第k年的引文数量的平均值。借助Ck可以构建R族科学发展节律指标，定义为引文观察值和引文期望值的比值，用于反映科学发展的节律。R族指标包括4项指标：①指标R——被引年视角加三角形引文窗口；②指标R’——被引年视角加平行四边形引文窗口；③指标r——引用年视角加三角形引文窗121；④指标r’——引用年视角加平行四边形引文窗口。以Journal of Documentation为例，本文具体说明了R族序列的计算和R族指标的应用。
基金supported by the National Natural Science Foundation of China (10961011)the Slovene Human Resources and Scholarship Fundthe Slovenian Research Agency, by the Nova Kreditna Banka Maribor, by TELEKOM Slovenije and by the Transnational Access Programme at RISC-Linz of the European Commission Framework 6 Programme for Integrated Infrastructures Initiatives under the project SCIEnce (Contract No. 026133)
文摘We describe an approach to studying the center problem and local bifurcations of critical periods at infinity for a class of differential systems. We then solve the problem and investigate the bifurcations for a class of rational differential systems with a cubic polynomial as its numerator.
基金the Fundation of Hubei Education Bureau(2003A008).
文摘In this paper, we discuss the complex isochronicity of a sixth degree polynomial system. We first adopt a new algorithm to find necessary conditions for complex isochronicity, then prove the sufficient conditions using effective methods.
文摘In this paper, we study the appearance of limit cycles from the equator and isochronicity of infinity in polynomial vector fields with no singular points at infinity. We give a recursive formula to compute the singular point quantities of a class of cubic polynomial systems, which is used to calculate the first seven singular point quantities. Further, we prove that such a cubic vector field can have maximal seven limit cycles in the neighborhood of infinity. We actually and construct a system that has seven limit cycles. The positions of these limit cycles can be given exactly without constructing the Poincare cycle fields. The technique employed in this work is essentially different from the previously widely used ones. Finally, the isochronous center conditions at infinity are given.
文摘Here we report the first direct Rb-Sr dating of pyrites and ores using sub-sampling from lode gold deposits in Linglong, Jiaodong Peninsula, which is a supra-large lode gold deposit and propose this as a useful geochronological technique for gold mineralization with poor age constraint. The Rb-Sr data of pyrites yield an isochron age of (121.6±8.1) Ma, whereas those of ore and ore-pyrite spread in two ranges from 120.0 to 121.8 Ma and from 110.0 to 111.7 Ma. Studies of characteristic of gold deposit and microscopy of pyrite and quartz indicate that the apparent ages of ore and ore-pyrite are not isochron ages, only mixed by two end members, i.e. the primitive hydrothermal fluids and wall rocks, whereas the isochron age of pyrite sub-samples constrains the age of gold mineralization (121.6±8.1) Ma, i.e. early Cretaceous, which is in good agreement with the published SHRIMP zircon U-Pb ages.
基金This work was supportedby both the National Natural Science Foundation of China and the National Key Project for Basic Research on the Tibetan Plateau (Grant Nos. 49772107, 49802005 and G1998040800) the U.S. National Science Foundation (EAR-9805318)
文摘We report a combined internal and whole-rock Sm-Nd isochron age, and Nd and Pb isotopic data for gabbro dikes of the Luobusha ophiolite in Tibet. The Sm-Nd isochron of data for two whole rocks and plagioclase and clinopyroxene separates from one of the rocks yields a Middle Jurassic age of (177±31) Ma (with an initial εNd(t) = +8), which provides a significant bound on the time of formation of the Luobusha ophiolite. The Nd and Pb isotopic charac-teristics of the dike indicate an Indian-Ocean-type isotopic affinity, and we conclude that the Luobusha ophiolite formed in an oceanic setting during the Middle Jurassic.
文摘The REE patterns of the basic volcanic rocks in Mangya area, Altun, are slight rich in LREE with (La/Ya)-N=1.69-3.20, (La/Sm)-N=1.37-1.87, other trace element ratios of the rocks are Th/Ta≈1 (for a few samples greater than 1.5), Nb/Y=0.34-0.62, Ti/Y=310-443 (on the average: 381), Ti/V=37-62, Zr/Nb=9.4-12.4, Sr/Rb=12-80 (on the average: 37), and Nb/Th=7.7-16.8. These features are similar to that of E-MORE or OIB. The ε Nd(t) value, being 3.95- 4.12, shows that the source of the volcanic rocks is derived from depleted asthenosphere mantle mixed with materials from enriched mantle. These, together with the information of geological setting and rock assemblages, indicate that the basic volcanic rocks are of ophiolite. The Sm-Nd isotope ages for the eight basic volcanic rock samples construct a straight line with good correlation, and the calculated isochron age is (481.3±53) Ma. Besides, the eight calculated ε Nd(t) and model ages are close to each other, which suggests that they are homologous, so the isochron is not a mixed line. In the meantime, the isochron age ((481.3±53) Ma) is lower than the model ages (T DM=1 004-1 534 Ma) of the samples, suggeting that the isochron age represents the formation age of the basic volcanic rocks and the ophiolite belt in Mangya area, Altun is formed in the early Paleozoic (Cambrian-Ordovician). In spite of the greater uncertainty of the age, it is still reliable because it is consistent with the age constrained by the regional strata.
基金This work was supported by the Chinese Academy of Sciences(Grant Nos.KZCX1-Y-03 and KZ951-A1-404).
文摘The Pengjiakuang, Dazhuangzi and Fayunkuang gold deposits, located on the northern margin of the Mesozoic Jiaolai Basin, east of Shandong Province, are controlled by a low-angle normal fault. Gold ores are typically brecciated, veinlet and disseminated. The Ar-Ar and Rb-Sr isochron dating methods were adopted to date ores and lamprophyre dike. The results indicate that the age of the Pengjiakuang gold deposit is 117.33—118.42 Ma, that of the Dazhuangzi gold deposit is 117.39 Ma, and that of the Fayunkuang gold deposit is (128.49±7.2) Ma. The consistency in metallogenic age between the gold deposits on the margin of the Jiaolai Basin and the gold deposits (115—126 Ma) of the northern uplift area suggests that both were formed in the same metallogenic period. That is to say, the large-scale metallogeny of the Jiaodong region took place in late-Yanshannian ((120±10) Ma).
文摘Geologists have been paying much attention to the characteristics and age of the basement of the Tarim Block. Recently, some isotopic ages for the Precambrian rocks in the margin areas of the Tarim Block have been obtained. The oldest age presented by the above study is 2487±5.1 Ma determined with evaporated Pb-isotope method for zircons of the blue quartz-bearing granite from the Kuruktag area. However, the possibility of the Archaean basement of Tarim Block was only deduced. In this study the age of 3.3 Ga
