共查询到20条相似文献,搜索用时 78 毫秒
1.
本文描述了陕西宁强早奥陶世Arenig期赵家坝组的疑源类,根据Arbusculidim、Coryphidium和Striatotheca等典型分子,将其归入环冈瓦纳疑源类古生物地理区。 相似文献
2.
陕西宁强赵家坝组阿伦尼克期疑源类 总被引:4,自引:1,他引:3
本文描述陕西宁强早奥陶世Arenig期赵家坝组的疑源类,根据Arbusculidium,Coryphidi-um和Striatotheca等典型分子,将其归入环冈瓦纳疑源类古生物地理区。 相似文献
3.
贵州三都地区阿伦尼克期疑源类的发现及其意义 总被引:5,自引:2,他引:3
本文首报报道了发现贵州三都地区同高组下段的疑源类化石,属种丰富,保存完好,它们多见于阿伦尼克期至兰维尔期,其中有些分子仅限一阿伦尼克期,根据组合中出现较多的Striatotheca,Coryphidium和Arbusculidium等,认为本区可能属地中海疑源类生物区,详细研究这些化石对认识疑源类组合与笔石带的关系有重要意义。 相似文献
4.
《微体古生物学报》2018,(4)
新疆塔里木盆地西北缘阿克苏和柯坪地区达瑞威尔期末期至凯迪期中期地层发育良好,大湾西沟剖面、四十场剖面和铁热克阿瓦提剖面地层保存良好的疑源类组合。该组合包括20属36种疑源类,以棘刺类、光球类和梭形类占优势。塔里木盆地西北缘疑源类组合与国内、外同期组合对比表明晚奥陶世疑源类古地理分区性减弱,部分疑源类分子分布仅限于晚奥陶世,且古地理分布广泛,具有生物地层学对比的潜力。新疆塔里木盆地西北缘数条剖面疑源类组成和多样性变化的不同可能与小环境的差异有关。本研究中疑源类属种组成及多样性变化趋势和柯坪地区海平面变化一致,反映了萨尔干组到其浪组下部有一次海侵过程。 相似文献
5.
贵州黄花冲下奥陶统湄潭组疑源类 总被引:4,自引:0,他引:4
对贵州黄花冲奥陶系湄潭组Azygograptus suecicus带疑源类组合研究表明,该组合可以与扬子区陕南、川东南、黔北、黔南、湘西、鄂西等地同期组合对比,并根据特征分子产出判别该组合应划归环冈瓦纳疑源类生物地理区。鄂西宜昌大湾组疑源类组合与黄花冲湄潭组疑源类组合的差异系环境因素所致。 相似文献
6.
Striatotheca是地中海疑源类生物区的特征分子,该属主要分布于阿仑尼格期至兰维恩期。描述了产于贵州三都地区同高组下段(N2—N4笔石带)Striatotheca的两个新种,它们是S.granula-tasp.nov.和S.sanduensissp.nov. 相似文献
7.
塔里木盆地西南缘晚泥盆世疑源类 总被引:6,自引:1,他引:5
塔里木盆地西南缘奇自拉夫组产疑源类6属11种(含7个新种),国内外晚泥盆世代表分子Gorgonisphaeridiumohioense出现于当前疑源类组合,指示其时代应为晚泥盆世(Famennian);对疑源类的生态环境、围岩特征及同层其它生物群的综合分析,表明奇自拉夫组为海相近岸沉积。 相似文献
8.
陕西宁强早志留世宁强组疑源类 总被引:2,自引:0,他引:2
陕西宁强早志留世宁强组中产有丰富的疑源类化石,其中大部分为西欧、北美同期地层中的常见分子。描述疑源类11属21种,包括2新种:Elektoriskos minutus sp.nov.和Palaeohystrichosphaeridium ningqiangense sp.nov.。 相似文献
9.
论山西中元古代晚期汝阳群微体化石组合 总被引:6,自引:0,他引:6
我国北方18-19亿年前的串岭沟组中获得的大球形疑源类,迄今,被认为是可信的最古老真核化石记录。自上世纪80年代以来,东秦岭北坡的中元古代晚期汝阳群陆续发现了丰富的球形光面疑源类,具刺疑源类,丝状微体化石和一些有疑问的动物遗迹。很显然,在中元古代晚期真核生物曾有重大辐射。 相似文献
10.
新疆大湾沟晚奥陶世疑源类 总被引:2,自引:1,他引:1
新疆塔里木盆地西北缘大湾沟剖面晚奥陶世地层发现保存良好的疑源类组合。该组合包括17属27种,以棘刺类(特别是Baltisphaeridium)占优势;其次为梭形类,以Navifusa为代表。大湾沟疑源类组合与世界其它地区同期组合对比表明,在晚奥陶世时疑源类古生物地理分区性减弱,不及早—中奥陶世明显。该组合中有13个种仅分布于“Caradoc”—“Ashgill”期,地理分布广泛,因而颇具生物地层学潜力。 相似文献
11.
Summary Concentration of N, P, K, Ca, Mg and S in summer groundnut crop was higher than in kharif while Zn, Fe, Mn and Cu contents were higher in summer crop. Kernel's N, P and Zn; Leaflet's Ca and Mn; Stem's K and Fe; Root's S and Cu and Petiole's Mg contents were highest. Shell's N, P, K, Mg, S, Zn and Cu; Kernel's Ca, Fe and Mn contents were the least. N, P, K, S, Zn and Cu concentrations decreased linearly as the crop grew. Ca, Mg, Fe and Mn concentrations did not display any distinct pattern. Ca concentration was positively correlated with pod yield in both the seasons. 相似文献
12.
The goal of this article was to establish reference ranges of the concentration of trace elements in human serum and to compare
these results with those reported by other authors. We describe the sample preparation and measurement conditions that allow
the rapid, precise, and accurate determination of Al, As, B, Be, Cd, Co, Cu, Fe, Li, Mn, Mo, Ni, Rb, Se, Sr, and Zn in human
serum samples (n=110) by inductively coupled plasma-mass spectrometry (ICP-MS). Accuracy and precision were determined by analyzing three
reconstituted reference serum samples by comparison with other methods and by the standard addition procedure.
The advantages of the ICP-MS method include short time of analysis of the elements mentioned, low detection limit, high precision,
and high accuracy. Disadventages include a high risk of contamination due to the presence of some of the elements of interest
in the environment, the relatively delicate sample handling, and the high cost of the equipment. 相似文献
13.
G. V. Iyengar 《Biological trace element research》1987,12(1):263-295
This report attempts to formulate reference ranges of elemental concentrations for 15 trace elements in selected human tissues
and body fluids.
A set of samples consisting of whole blood, blood serum, urine, milk, liver, and hair were chosen and considered for 15 elements
of biological significance: As, Cd, Co, Cr, Cu, F, Fe, I, Hg, Mn, Mo, Ni, Pb, Se, and Zn. The results represent wholly or
partially data received from 40 countries of the global regions of Africa, Asia, Europe, North, South, and Central America,
Australia, and New Zealand.
This survey, even if qualitative, has been useful in demonstrating certain trends of trace-element scenarios around the world.
It is of course recognized that both diet and environment exert a strong influence on the distribution pattern of several
elements, such as As, Cd, Mn, Pb, Se, and Zn. A limited comparison of the available information on soil status of different
countries reflected some interesting associations for elements, such as Mn and Zn.
Importantly, this study revealed that only a few countries were in a position to identify a reasonable amount of data on samples
requested for this project. Regretably, for a number of countries, any dependable data for even such essential elements as
Cu, Fe, and Zn were not available.
In view of the nutritional importance of many elements, the time is ripe for concerted efforts by intergovernmental agencies
to initiate investigations or commission task forces/projects to generate reliable reference data for selected global regions,
which sadly lack data of any kind at present. 相似文献
14.
The unitary conductances and permeability sequences of the rat connexin40 (rCx40) gap junction channels to seven monovalent cations and anions were studied in rCx40-transfected neuroblastoma 2A (N2A) cell pairs using the dual whole cell recording technique. Chloride salt cation substitutions (115 mM principal salt) resulted in the following junctional maximal single channel current-voltage relationship slope conductances (γj in pS): CsCl (153), RbCl (148), KCl (142), NaCl (115), LiCl (86), TMACl (71), TEACl (63). Reversible block of the rCx40 channel was observed with TBA. Potassium anion salt γj are: Kglutamate (160), Kacetate (160), Kaspartate (158), KNO3 (157), KF (148), KCl (142), and KBr (132). Ion selectivity was verified by measuring reversal potentials for current in rCx40 gap junction channels with asymmetric salt solutions in the two electrodes and using the Goldman-Hodgkin-Katz equation to calculate relative permeabilities. The permeabilities relative to Li+ are: Cs+ (1.38), Rb+ (1.32), K+ (1.31), Na+ (1.16), TMA+ (0.53), TEA+ (0.45), TBA+ (0.03), Cl− (0.19), glutamate− (0.04), and NO3− (0.14), assuming that the monovalent anions permeate the channel by forming ion pairs with permeant monovalent cations within the pore thereby causing proportionate decreases in the channel conductance. This hypothesis can account for why the predicted increasing conductances with increasing ion mobilities in an essentially aqueous channel were not observed for anions in the rCx40 channel. The rCx40 effective channel radius is estimated to be 6.6 Å from a theoretical fit of the relationship of relative permeability and cation radius. 相似文献
15.
A new polynitro cage compound 2, 4, 6, 8, 10, 12, 13, 14, 15-nonanitro-2, 4, 6, 8, 10, 12, 13, 14, 15-nonaazaheptcyclo [5.5.1.1(3,11).1(5,9)] pentadecane (NNNAHP) was designed in the present work. Its molecular structure was optimized at the B3LYP/6-31 G(d,p) level of density functional theory (DFT) and crystal structure was predicted using the Compass and Dreiding force fields and refined by DFT GGA-RPBE method. The obtained crystal structure of NNNAHP belongs to the P-1 space group and the lattice parameters are a = 9.99 ?, b = 10.78 ?, c = 9.99 ?, α = 90.01°, β = 120.01°, γ = 90.00°, and Z = 2, respectively. Based on the optimized crystal structure, the band gap, density of state, thermodynamic properties, infrared spectrum, strain energy, detonation characteristics, and thermal stability were predicted. Calculation results show that NNNAHP has detonation properties close to those of CL-20 and is a high energy density compound with moderate stability. 相似文献
16.
17.
The aim of this report has been to present results concerning analytical quality controls of Hg analysis of fish and sediment, analyses of Fe, Ca, total-P, K, pH, alkalinity, conductivity, colour and hardness (Ca + Mg) of lake water samples. Despite the fact that these are standard parameters in many regular water control programs, there are major differences in the reliability with which these parameters can be determined. The focus here is on an overall inter-laboratory comparison between the parameters. Six laboratories have been involved in the analysis. Selected results: pH gives the lowest (average) relative standard deviation (error), about 2 %; conductivity gives an error of about 5–7 %; alkalinity yields an average error of as much as 13–25 %, which is the largest among the parameters studied here; colour also gives a high error, 9–15 %; hardness gives a relative standard deviation of about 6–7 %. Of the other parameters (i. e., Hg, Fe, Ca and P), Hg gives the best reliability and Fe and P the lowest. To have knowledge of the reliability of the analytical data is of paramount importance in most control programs and research projects. 相似文献
18.
We investigated the uptake of inorganic elements (Be, Na, Mg, K, Ca, Sc, Mn, Co, Zn, Se, Rb, Sr, Y, Zr, Ce, Pm, Gd, and Hf)
and the effect of Ca on their uptake in carrots (Daucus carota cv. U.S. harumakigosun) by the radioactive multitracer technique. The experimental results suggested that Na, Mg, K, and
Rb competed for the functional groups outside the cells in roots with Ca but not for the transporter-binding sites on the
plasma membrrane of the root cortex cells. In contrast, Y, Ce, Pm, and Gd competed with Ca for the transporters on the plasma
membrane. The selectivity, which was defined as the value obtained by dividing the concentration ratio of an elemental pair,
K/Na, Rb/Na, Be/Sr, and Mg/Sr, in the presence of 0.2 and 2 ppm Ca by that of the corresponding elemental pair in the absence
of Ca in the solution was estimated. The selectivity of K and Rb in roots was increased in the presence of Ca. The selectivity
of Be in roots was not affected, whereas the selectivity of Mg was increased by Ca. These observations suggest that the presence
of Ca in the uptake solution enhances the selectivity in the uptake of metabolically important elements against unwanted elements. 相似文献
19.
The variation with age of the 18 trace element mass fractions and some histological characteristics of intact prostate glands of 50 subjects aged 0–30 years was investigated by instrumental neutron activation analysis, inductively coupled plasma atomic emission spectrometry, and a quantitative morphometric analysis. Mean values ± standard error of the mean (M ± SΕΜ) for the mass fractions (in milligrams per kilogram wet tissue) of these trace elements in pre-puberty were: Al 28.5 ± 9.0, B 0.40 ± 0.11, Ba 1.48 ± 0.44, Br 10.5 ± 1.5, Ca 241 ± 30, Cl 3,203 ± 278, Cu 3.51 ± 0.89, Fe 33.7 ± 4.1, K 2,364 ± 145, Li 0.020 ± 0.004, Mg 153 ± 23, Mn 0.46 ± 0.06, Na 2,286 ± 130, P 1,391 ± 100, S 1,698 ± 132, Si 62 ± 11, Sr 0.38 ± 0.08, and Zn 27.6 ± 2.3. During puberty and postpuberty, when there is a significant increase in circulating androgens, the mean values were: Al 7.2 ± 1.4, B 0.21 ± 0.05, Ba 0.25 ± 0.06, Br 5.8 ± 1.0, Ca 433 ± 81, Cl 2,314 ± 201, Cu 1.77 ± 0.13, Fe 20.9 ± 1.6, K 2,585 ± 118, Li 0.0088 ± 0.0014, Mg 232 ± 27, Mn 0.34 ± 0.04, Na 1,875 ± 107, P 1,403 ± 98, S 1,673 ± 73, Si 22.2 ± 3.1, Sr 0.22 ± 0.03, and Zn 93.3 ± 8.9. Mean values (M ± SΕΜ) of percent volumes (%) of the stroma, epithelium and lumen in the prostate before puberty were 73.4 ± 2.6, 20.4 ± 1.7, and 4.45 ± 0.94, respectively, versus 46.5 ± 2.5, 38.5 ± 1.9, and 14.9 ± 1.2 during puberty and postpuberty. This work’s results confirm that the Zn mass fraction in prostate tissue is an androgen-dependent parameter. For the first time it has been demonstrated that the glandular lumen is a main pool of Ca, Mg, and Zn accumulation and that the stroma is a main pool of Al, B, Ba, Br, Cl, Cu, Fe, Mn, Na, and Si accumulation in the normal human prostate, for the age range 0–30 years. It was concluded that the Ca, Mg, and Zn binds tightly within the prostatic fluid, because the volume of glandular lumen reflects the volume of prostatic fluid. 相似文献
20.
Vladimir Zaichick Sofia Zaichick Vasilii Karandashev Sergey Nosenko 《Biological trace element research》2009,129(1-3):107-115
The effect of age and gender on major, minor, and trace element contents in the intact rib bone of 80 relatively healthy 15–55-year-old women and men was investigated. Contents or upper limit of contents of 16 chemical elements in the rib bone were determined by inductively coupled plasma atomic emission spectrometry (ICP-AES). Mean values (M?±?SΕΜ) for the mass fraction of Ba, Ca, Cu, Fe, K, Li, Mg, Na, P, S, Sr, and Zn (milligram per kilogram of dry bone) were as follows: 2.54?±?0.16, 171,400?±?4,050, 1.35?±?0.22, 140?±?11, 1,874?±?71, 0.049?±?0.011, 2,139?±?38, 5,378?±?88, 75,140?±?1,660, 1,881?±?51, 291?±?20, and 92.8?±?1.5, respectively. The upper limits of contents of Al, B, Mn, and V were <7.20, <0.65, <0.36, and <0.03, respectively. Statistically significant tendency for the Ca, Mg, and P content to decrease with age was found in the human rib bone, regardless of gender. The mass fraction of Fe in the male rib bone increases with age. It was shown that higher Ca, Mg, Na, P, and Sr mass fractions as well as lower Fe content were typical of female ribs as compared to those in male ribs. 相似文献