isotope
isotope的相关文献在1986年到2022年内共计108篇,主要集中在地质学、肿瘤学、化学
等领域,其中期刊论文108篇、相关期刊39种,包括地学前缘、中国科学、中国科学等;
isotope的相关文献由344位作者贡献,包括LIU、WANG、ZHANG等。
isotope
-研究学者
- LIU
- WANG
- ZHANG
- Jie Yuan
- CHENG
- LI
- Masao Nomura
- WU
- YU
- ZHOU
- 2 Universitt Bern Isotopengeologie Erlachstrasse 9a CH3012 BernSwitzer and
- 2.Scripps Institution of Oceanography University of California San Diego La
- 3 Dip. Scienze della Te
- A. K. M. Azad Shah
- A.Ergun
- A.S.Botvina
- Abdoul Aziz Gning
- Akio Makishima
- Alexander A. Bukhvostov
- Alexander S. Vedenkin
- Amnon Rosenfeld
- Anatoliy Nikolaev
- Andréa Dardes de Almeida Castanho
- Arnold N. Onyango
- Asami Suzuki Mashio
- Bai Guoping John B Keene Department of Geology and Geophysics University of Sydney Sydney Australia 2006
- Baorong Yang
- Bingsong
- BoLin
- Boris Verkhovsky
- C. Jiménez de Cisneros
- CHEN
- CHEN Bin
- CHEN Jiafu
- CHEN Wenxi
- Chang-yuan Tang
- ChiYang
- Chris Anani
- Christopher Teh
- Chunmei
- Chunyan Yao
- Congqiang(刘丛强)
- D.Visona 1 I.M.Villa 2 P.Pertusati 3 B.Lombardo 4(1 Dip. Mineralogiae Petrologia corso Garibaldi 37 I35137 PadovaItaly
- DEBOR A AHANSSEN
- DING
- DONG
- DONG Chunyu
- DUAN
- Damba Yahaya
- Daniel Asiedu
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Lamzira Parulava;
Levani Eliashvili;
Vakhtang Betlemidze;
Natia Mzareulishvili
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摘要:
Nitrogen-15 isotope-modified compounds are widely used in medicine, pharmacology, agriculture and various fields of science and their nomenclature is gradually increasing. Their widespread use depends on the availability of inexpensive and simple isotope analysis methods. The present article is an attempt to determine the nitrogen-15 isotope content directly in organic compounds without their conversion. The general principle of possibility of determination of the isotopes of nitrogen directly in organic compounds is proposed. Based on the study of mass-spectra of Carbamide Carbonyldiamide, isocyanic acid and nitrobenzene the mass peaks are selected, by which it is possible to determine the atomic fraction of the isotopes of nitrogen. The respective formulas are proposed.
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Han Zhang;
Zong-yu Chen;
Chang-yuan Tang
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摘要:
Since water resources of the Heihe River Basin are primarily in the form of surface runoff in the Qilian Mountains,identifying its sources and components is essential for researchers to understand water cycling and transformation in the basin.It will help to properly exploit water resources,and contribute to ecological environment construction.The paper uses the isotope data of hydrogen and oxygen in water and hydrochemistry data collected at a high altitude to trace the sources of surface runoff in Heihe River in rainy season and uses the three-component mixing model to estimate the contribution of each component to runoff.Results indicate that surface water consists of precipitation,melt water and groundwater,with precipitation being the primary component and contributing to 59%-64%of runoff.Melt water and groundwater account for 15%-25%and 12%-22%,respectively.Precipitation accounts for 60%,groundwater for 22%and glacial melt water for 18%of the outflow in the main stream of the Heihe River.The composition is of great significance for water cycling and conversion research as well as water resource evaluation and management.
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MA Xu;
CHEN Bin;
CHEN Jiafu
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摘要:
Objective Though the Central Asian Orogenic Belt (CAOB) is characterized by widespread Phanerozoic crustal growth,there is little juvenile crust documented in its southeastern segment,northern margin of the North China Craton(NCC)(Zhang et al,2007,2009).Late Carboniferous Dongwanzi ultramafic-mafic cumulate complex occurs in northern margin of the NCC and is intruded by a syenite with depleted Sr-Nd isotopes (Ma et al.,2014).However,the age and petrogenesis of this syenite is poorly constrained.In this study,we present new petrological,zircon U-Pb and Hf isotopic data of the Dongwanzi syenite,in order to put insights on its formation age and petrogenetic relationship with cumulates.
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JIA Wenbin;
LI Yongsheng;
MI Kuifeng;
YU Xiaofei
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摘要:
Objective The Altyn Tagh marks the northern margin of the Qinghai-Tibet Plateau and lies between the Tarim block to the north and the Qaidam block,Qilian Orogen,and Kunlun orogenic belt to the south.The Altyn Tagh region contains ophiolite,high-to ultrahigh-pressure metamorphic rocks,and igneous rocks.Previous research has virified the occurrence of continental rifting,subduction,slab roll-back,and collision between the Tarim block and Proto-Tethys oceanic plate.Moreover,Kaladaban volcanic rocks are mainly distributed in the north Altyn region.Studies of the magmatic evolution of this region have proposed that Altyn oceanic plate was subducted during the Ordovician(Han et al.,2012;Wang et al.,2017).However,the specific timing and other aspects of the subduction are debated,and an investigation of granite porphyry in the Kaladaban area would improve our understanding of this subduction event.In this study,we present new U-Pb zircon dating result and Sr-Nd isotope composition data for granite porphyry from the North Altyn region.The objective is to constrain the timing of subduction of the North Altyn oceanic plate and establish the petrogenesis and magma source of the granite porphyry.
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Damba Yahaya;
Nicholas Denwar;
Mustapha Mohammed;
Matthew W. Blair
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摘要:
To explore the variations in symbiotic N2 fixation and water use efficiency in cowpea, this study evaluated 25 USDA cowpea genotypes subjected to drought under field conditions at two locations (Kpachi and Woribogu) in the Northern region of Ghana. The 15N and 13C natural abundance techniques were respectively used to assess N2 fixation and water use efficiency. The test genotypes elicited high symbiotic dependence in association with indigenous rhizobia, deriving between 55% and 98% of their N requirements from symbiosis. Consequently, the amounts of N-fixed by the genotypes showed remarkable variations, with values ranging from 37 kg·N-fixed·ha-1 to 337 kg·N-fixed·ha-1. Most genotypes elicited contrasting symbiotic performance between locations, a finding that highlights the effect of complex host/soil microbiome compatibility on the efficiency of the cowpea-rhizobia symbiosis. The test genotypes showed marked variations in water use efficiency, with most of the genotypes recording higher δ13C values when planted at Kpachi. Despite the high symbiotic dependence, the grain yield of the test cowpeas was low due to the imposed drought, and ranged from 56 kg/ha to 556 kg/ha at Kpachi, and 143 kg/ha to 748 kg/ha at Woribogu. The fact that some genotypes could grow and produce grain yields of 627 - 748 kg/ha under drought imposition is an important trait that could be tapped for further improvement of cowpea. These findings highlight the importance of the cowpea-rhizobia symbiosis and enhanced water relations in the crop’s wider adaptation to adverse edaphoclimatic conditions.
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Tamara Bayanova;
Viktor Subbotin;
Svetlana Drogobuzhskaya;
Anatoliy Nikolaev;
Ekaterina Steshenko
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摘要:
Baddeleyite is an important mineral geochronometer. It is valued in the U-Pb (ID-TIMS) geochronology more than zircon because of its magmatic origin, while zircon can be metamorphic, hydrothermal or occur as xenocrysts. Detailed mineralogical (BSE, KL, etc.) research of baddeleyite started in the Fennoscandian Shield in the 1990s. The mineral was first extracted from the Paleozoic Kovdor deposit, the second-biggest baddeleyite deposit in the world after Phalaborwa (2.1 Ga), South Africa. The mineral was successfully introduced into the U-Pb systematics. This study provides new U-Pb and LA-ICP-MS data on Archean Ti-Mgt and BIF deposits, Paleoproterozoic layered PGE intrusions with Pt-Pd and Cu-Ni reefs and Paleozoic complex deposits (baddeleyite, apatite, foscorite ores, etc.) in the NE Fennoscandian Shield. Data on concentrations of REE in baddeleyite and temperature of the U-Pb systematics closure are also provided. It is shown that baddeleyite plays an important role in the geological history of the Earth, in particular, in the break-up of supercontinents.
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Nguyen Thi Hong Thinh;
Vu Hoai;
Ha Lan Anh;
Vo Thi Anh;
Truong Viet Chau;
Trinh Van Giap;
Tran Minh Tien
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摘要:
In this study, the experiments on field were conducted to examine the change in the content of soil organic carbon (SOC), its C-13 stable isotope composition (δ 13C) and some main physical, chemical parameters (soil moisture, pH, soil density, content of humic, fulvic, total N, total P, total K) in alluvial soil of Dan Phuong region—Vietnam at a depth of 0 - 30 cm when we changed the regime from 2 maize -1 rice crop to 2 rice - 1 maize crop per 1 year. In addition to analyzing the main parameters in soil, C content and its δ 13C value in parts of rice and maize (root, stem and leaf) were also analyzed to assess the contribution of plant residues on soil organic carbon content after harvest. The experiment was carried out in 2016-2017 on the field with the traditional farming method of local farmers along with the tropical monsoon weather conditions of the North-Vietnam. The results showed that SOC had positive correlation with total N, total P parameters and negative correlation with δ 13C values of soil samples at two layers (0 - 15 cm and 15 - 30 cm). The average of total dry biomass (stem, stump + roots and leaf parts) per 1 rice and 1 maize crop was 10.64 Mg/ha and 9.09 Mg/ha, respectively. The average of δ 13C value of rice (C3 plant) was -29.78‰ and its value of maize (C4 plant) was -12.61‰. The new plant (rice) contributes to the total soil organic carbon content from 11.31% to 44.14% at the 0 - 15 cm layer and from 6.55% to 11.31% at the 15 - 30 cm layer in one-year experiment period.
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Sergei V. Stovbun;
Kirill V. Ermakov;
Alexander A. Bukhvostov;
Alexander S. Vedenkin;
Dmitry A. Kuznetsov
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摘要:
A conventionally synthesized thio- and cyano-modified single-stranded poly(dNTP) sequences of different molecular sizes (20n - 200n) and the same lengths routine poly(dNTP) and poly(NTP) species were obtained through the good services provided by the Russian Federal Bioorganic Products Group and by the ThermoFischer, Inc., and then tested for their impact on catalytic activities of β-like DNA polymerases from chromatin of HL-60, WERI-1A and Y-79 cells as well as for the affinity patterns in DNApolβ-poly(dNTP)/ (NTP) pairs, respectively. An essential link between the lengths of ultrashort (50n - 100n) single-stranded poly(dNTP) sequences of different structures and their inhibitory effects towards the cancer-specific DNA polymerases β has been found. A possible significance of this phenomenon for both DNA repair suppression in tumors and a consequent anti-cancer activity of the DNA repair related short poly(dNTP) fragments has been for the first time emphasized with a respect to their pharmacophore revealing potential. Thus, this work presents an experimental attempt to upgrade a contemporary attitude towards the DNA derived products applied for anti-cancer agenda, particularly, for acute myeloid leukemia and retinoblastoma cell DNA repair machinery breakdown. In this study, tumor specific DNA polymerases β were found of being the targets for attack promoted with the primer-like single-stranded DNA fragments followed by consequent cytostatic phenomena. A novel concept of the DNA related anti-cancer medicines is under discussion.
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Mansour Gueye;
Abdoul Aziz Gning;
Mapathé Ndiaye;
Fatou Diop Ngom;
Raymond Malou;
El Hadj Sow;
Raphael Sarr
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摘要:
On the northern coast of the Cape Verde peninsula, Lake Retba is one of the few depressions that have preserved its water body due to the drought that plagued the Sahel in the 1960s. The aim of this article is to understand the resilience of the lake to the drought. For this purpose, a deep knowledge of interactions between the different components of the hydro-system, namely: lake, dune tablecloth, ponds and ocean is necessary. The use of electrical resistivity tomography (ETR) and chemical and isotopic tools yielded conclusive results. Electrical tomography of resistivity (ETR) shows throughout the coastal dune a superposition between fresh and salt water, with even a predominance of salt water at the level of the old canal. The chemistry of the major ions and isotopes confirms this contact between the saltwater bison of the sea and the lake by showing a superposition of the fresh/brackish waters on the salty waters of the bevel, which, in turn, are found in the very salty waters influenced by the lake. This translates a feeding of the lake by the sea through the bevel. At the canal level, this feeding is done, on the surface, by means of ponds whose water characteristics show that they constitute an outcrop of the bevel. The freshwater body of the coastal dune that floats on salt water in the form of a lens also flows into the lake. The feeding of the lake, by the sea through the bevel and the ponds, and by the water table, is therefore effective and attested by all the methods used in this work. It allowed the resilience of the lake against the drought. This inflow of seawater into the lake is at the origin of its salinization and therefore of the salt that settles on the bottom. This study shows that the survival of the lake also depends on safeguarding the ponds located in the north of the lake.