对美国海权之路"天时"的思考

踏上海权之路伊始,美国极力避免挑战海军强国,通过与法国的私掠战、第二次英美战争以及南北内战锻炼了自己的海军队伍。19世纪末,利用英国受困于欧洲的有利国际形势,美国通过在大西洋采取守势,向太平洋扩张,实现了海权的振兴。美国的海权发展历程表明,只有在适宜的国际环境下,应“天时”而动,才能突破海权强国的围剿,实现海权的飞跃。     

40Ar-39Ar ages of the Louzidian-Dachengzi ductile shear zone near Chifeng, Inner Mongolia and their tectonic significance

The Louzidian normal fault occurs as the eastern detachment fault of the Kalaqin metamorphic core complex. Field observations and microstructural analyses reveal that the Louzidian-Dachengzi ductile shear zone developed in its lower-plate was genetically related to sinistral strike-slips and extensional faulting. Two samples from this ductile shear zone yield ⁴⁰Ar-³⁹Ar plateau ages of 133 Ma (Bi) and 126 Ma (Kp), which are concordant with their isochron ages. The plateau age of 133 Ma (Bi) records the formation age of the ductile shear zone. The inconsistent relationship between the earlier strike-slip ductile shear zone and the later normal fault makes the Kalaqin Quasi-metamorphic core complex distinctive from Cordilleran metamorphic core complex. These ages provide important geochronological data for putting constraints on the formation age and genesis of such ductile shear zones.     

40Ar-39Ar thermochronology of two ductile shear zones from Yiwulüshan, West Liaoning Region: Age constraints on the Mesozoic tectonic events

Two ductile shear zones trending EW and NNE respectively not only controlled the tectonic framework of the northern North China, but also constrained the geodynamic background for gold mineralization in this region. Field observations and microstructural analyses reveal that the EW trending ductile shear zones are mainly contributed to dextral compressional deformation resulting from top-to-the-southeast oblique thrust shearing, whereas the NNE trending ones are genetically related to sinistral strike-slip and extensional faulting. One sample from the former yielded an ⁴⁰Ar–³⁹Ar plateau age of (219± 4) Ma (Bi) and two samples from the latter gave ⁴⁰Ar–³⁹Ar plateau ages of (116± 2) Ma (Bi) and (127±3) Ma (Bi). These ages provide constraints on the top-to-the-southeast oblique thrusting event occurring in Late Triassic and the sinistral extensional and strike-slip faulting event which occurred in Early Cretaceous.     

Two closely linked rice U14 boxC/D snoRNAs

By analysis of the conserved elements in yeast U14 boxC/D snoRNA. the conserved elements in rice U14 boxC/D snoRNA have been speculated. Through computer search of the international rice genome database, two rice U14 snoRNA gene candidates are obtained. These two putative U14 snoRNA genes are closely linked on rice chromosome 2. The coding sequences of these two snoR-NAs exhibit the hallmark structure of boxC/D antisense snoRNA. They both have conserved boxC and boxD sequences and a 14nt-long complement to the sequence between 414nt and 427nt of rice 18S rRNA (according to GenBank accession no. X00755). The experimental evidence shows that these two snoRNAs are involved in the methylation of the complementary sequence of rice 18S rRNA. The existence and localization of these two snoRNAs are proved by RT-PCR and Northern blot. Further analysis shows that both of the newly found rice snoRNAs have high homology with maize U14 snoRNA. and they are named rice U14.1 snoRNA and U14.2 snoRNA respectively. The gene sequence encoding these two snoRNAs has been deposited in the GenBank database under accession number of AF332622.     

40Ar-39Ar thermochronology of two ductile shear zones from Yiwulüshan, West Liaoning Region: Age constraints on the Mesozoic tectonic events

Two ductile shear zones trending EW and NNE respectively not only controlled the tectonic framework of the northern North China, but also constrained the geodynamic background for gold mineralization in this region. Field observations and microstructural analyses reveal that the EW trending ductile shear zones are mainly contributed to dextral compressional deformation resulting from top-to- the-southeast oblique thrust shearing, whereas the NNE trending ones are genetically related to sinistral strike-slip and extensional faulting. One sample from the former yielded an 40Ar-39Ar plateau age of (219±4) Ma (Bi) and two samples from the latter gave 40Ar-39Ar plateau ages of (116±2) Ma (Bi) and (127±3) Ma (Bi). These ages provide constraints on the top-to-the-southeast oblique thrusting event occurring in Late Triassic and the sinistral extensional and strike-slip faulting event which occurred in Early Cretaceous.     

合成U3snRNA基因上游启动区构建ACC合成酶反义RNA-核酶嵌合基因的植物表达载体

利用反义 RNA和核酶进行基因表达调控是当今植物分子生物学的研究热点之一 .但在转基因植物中 ,利用 RNA聚合酶 型启动区表达效率不高 .番茄 U3sn RNA基因由 RNA聚合酶 来转录 ,具有较高的转录效率 ,为一般转录效率的 1 0 0～ 1 0 0 0倍 .我们人工合成了番茄 U3sn RNA基因上游启动区 ( 1 5 2 bp) ,构建到番茄 ACC合成酶的反义 RNA-核酶嵌合 DNA序列的上游 ,然后将“启动区 -反义 RNA-核酶嵌合 DNA序列”插入到植物双元表达载体p GA6 4 3中 ,并用三亲融合法导入农杆菌 LBA4 40 4中 ,为研究 U 3sn RNA上游启动区增强反义 RNA-核酶基因的表达奠定了基础     

整流后倒U型管内气液两相流动的稳定性及流型分布

在倒U型管垂直段的两端内分别放置一个整流环，来消除入口弯头对垂直段流动的影响，通过对单相流体在倒U型管内的流动进行数值计算，以及对整流作用下倒U型管内气液流动的稳定性和流型的分布进行实验研究，发现整流环的整流作用可以增强管道内流动的稳定性，实验还发现，倒U型管垂直上升段内的间歇性流动（弹状流和块状流）区域减小，环状流区域增大，流动的稳定性增强。     

北祁连山西段石炭二叠系界线初析兼论对大黄沟群的再研究

在大量野外工作和充分讨论国内外石炭——二叠系界线划分意见的基础上,本文初步分析了北祁连山西段石炭——二叠系界线,讨论了该区大黄沟群、大黄沟组和山西组的关系及时代,指明早二叠世早期地层在北祁连山西段确实存在,没有缺失。     

工程数据库管理系统及其图形数据库的设计与实现

本文论述了工程数据库管理系统(EDBMS)的总体结构、功能及其实现环境.该系统采用关系和网状混合的数据模型,实现了图形数据和非图形数据的统一管理,并具备版本管理及控制、知识库管理等功能.     

水稻叶片叶龄判断方法研究

笔者于1982—1992年对58个水稻品种(包括杂交组合和制种亲本)进行的观察结果表明:水稻外观形态特征——双零叶、葫芦叶、植伤叶和伸长叶枕距是判断水稻叶片叶龄的依据.在秧田期间可用数记法和种谷方向来判断秧苗的叶龄;在水稻移栽后返青分蘖期,可根据第一双零叶、第一类葫芦叶、植伤叶来判断叶龄的变化;在幼穗分化期,可根据第二双零叶、第二类葫芦叶和伸长叶枕距来判断最后3片叶.