共查询到20条相似文献，搜索用时 15 毫秒
1.
Negative Bias Temperature Instability (NBTI) has become one of the most serious reliability problems of metal--oxide--semiconductor field-effect transistors (MOSFETs). The degradation mechanism and model of NBTI are studied in this paper. From the experimental results, the exponential value 0.25--0.5 which represents the relation of NBTI degradation and stress time is obtained. Based on the experimental results and existing model, the reaction--diffusion model with H + related species generated is deduced, and the exponent 0.5 is obtained. The results suggest that there should be H + generated in the NBTI degradation. With the real time method, the degradation with an exponent 0.5 appears clearly in drain current shift during the first seconds of stress and then verifies that H+ generated during NBTI stress. 相似文献
2.
In the asymmetric and symmetric nonlinear--metal--nonlinear dielectric structures, this paper studies the analytic dispersion relation for surface plasmon in a system consisting of a thin metallic film covered on two sides media of intensity-dependent refractive indexes by applying a generalised first integral approach. Especially in the symmetric waveguide structure, two possible modes can exist: the odd mode and the even mode. The dispersion relations of the two modes are obtained. Due to the nonlinear dielectric, the squared magnitude of the electric field at the interface appears and alters the dispersion relations. Numerical results are compared to those from a certain approximate treatment. 相似文献
3.
WANG Xian QIU Haiyuan CAI Zhenzhen CHEN Lidan ZHENG Shenghu HUANG Zhiwei 《海洋学报(英文版)》2006,25(2):153-158
1 IntroductionBiosorption is a processthatutilizes biomasstoabsorb heavy metalsand isparticularly usefulfortheremoval of contam inants from industrial effluents.Inartificialorganism scannotbe used in practicalpro-ductionbecauseoftheirlow density,low inten… 相似文献
4.
The study was to find out the effect of cadmium and mercury on levels of hemolymph glucose, crustacean hyperglycemic hormone (CHH) and hepatopancreas glycogen in the blue swimmer crab Portunus pelagicus. The experiments were performed in both intact and eyestalk ablated crabs. Quantification of CHH was done by the indirect ELISA with the aid of primary anti-Carcinus maenas-CHH antibody. Higher glucose concentration was observed on exposure to 8×10-6 of cadmium ((825.6±5.42) μg/mL) and 6×10-6 of mercury ((90.5±6.25) μg/mL) after 48 h and 24 h respectively. Higher level of hemolymph glucose was observed in eyestalk intact crabs on exposure to cadmium and mercury than eyestalk ablated crabs. Decrease in the levels of CHH was observed in both eyestalk intact and ablated crabs on heavy metal exposure. Decline of the hepatopancreas glycogen level was also witnessed with the exposure to heavy metal, which validated its utilization in the production of glucose. Thus this study brings to light, the variations in hemolymph glucose, CHH and hepatopancreas glycogen on heavy metal stress. These carbohydrate metabolites can be used as biomarkers in assessing heavy metal contamination in water bodies. 相似文献
5.
Li Jinxi Du Ronggui Zhang Gongxun C. S. Wong R. W. Macdonal W. K. Johnson 《海洋学报(英文版)》1990,9(3):389-403
The pathway and fate of heavy metals were studied in 10m3 enclosures at Xiamen Bay in 1985. The dissolved metals added are removed rather quickly during the first days, and their half-removal times ( t1/2) (d) are as follows: Pb 5. 4-5. 8, Hg 6. 7-14, Zn 11-22, Cu 16 - 29, and Cd 30-89. Zinc is transferred biologically to particles during phytoplankton bloom. The main Fate of added metals after 27 days is as follows; over 80% Cd and 60% Cu remain in dissolved phase, more than 60% Pb and 50% Hg transfer to settling settlement, while Zn is equally distributed in dissolved phase and settling settlement. The wall uptake is less than 2% of the total metals added. Organic materials play an essential role in the partition and the transfer of heavy metals in water column. Terrigenous and autochthonous particles show different affinities to different metals. Most heavy metals associate weakly with zooplankton. The Binding of Cd, Pb, Zn and Cu to the particles shows distinctive features related to the diagenetic 相似文献
6.
The Huanghe River estuary, as one of world-known large river estuary and its adjacent sea re-gion are important aquatic product base with rich marine product resources in North China. The au-thors collected about 60 species of fishes. crustacea. mollusca and polychaeta in this region (119°05′-20′E,37°15′-38°15′N) from Apri1 to May. 1984. The concentration of Zn, Cd, Pb and Cu in eachmarine organisms was measured and concentration factors of trace metals were calculated. The ashingmethods was used for sample treatments. The concentration of trace metals was determined by anti-adsorption physical coating mercury electrode inverse polarography (Davis A1660 Differential CathodRay Polarograph). 相似文献
7.
８５—９０４—０８—０１和８５—９０４—０８—０２通过评审１９９５年１２月１２—１３日，受国家科委委托地矿部科技司组织专家鉴定组，在北京对“八五”国家科技攻关项目的“８５—９０４—０８一川和８５—９０４—０８—０２”专题进行了评审。卜述两专题经过５年... 相似文献
8.
9.
Xiaoxiong Wang Jordi Garcia-Orellana Xiaogang Chen Jianan Liu Fenfen Zhang Jianguo Qu Zhuoyi Zhu Jinzhou Du 《海洋学报(英文版)》2023,(8):113-124
Submarine groundwater discharge(SGD) plays a major role as a conveyor of metals to coastal waters. However,the seasonal change of metal fluxes derived through SGD is unclear. Here, we evaluated the behaviours and fluxes of trace metals(Mn, Fe, Ba, Pb, U, Cr, Zn, Cu) in an estuary under different seasonal conditions. The behaviours of trace metals revealed that SGD was the source of Mn(3.51 mmol/(m2·d)), Fe(0.174 mmol/(m2·d)) and Ba(0.024 mmol/(m2·d)), but the Cu ... 相似文献
10.
The major elements, rare earth elements （REE） and trace elements of four basalt samples from central and western Pacific ferro- manganese crust provinces have been analyzed using chemical methods and ICP - MS, respectively. The results indicate that the samples have been extensively altered and that the contents of their major elements have changed significantly. However, the similarity of REE partition patterns and trace element contents of basalt samples to those of fresh oceanic island basalts （OIB） indicate that the basalt samples originated as OIB. Because of low-temperature alteration, the contents of A1203 , Fe203 , MnO, K20 and P205 increased, while MgO and FeO decreased. Active components, such as magnesium and iron, were leached from OIB resulting in the relative enrichment of SiO2. The leaching of active components can cause the relative enrichment of REE, while the precipitation of LREE-rich ferromanganese oxides in vesicles and fissures not only causes an increase of REE contents, but also induces ＂fractionation＂ of LREE and HREE. Based on the enrichment mechanism of REE contents, the theoretical quantities of precipitated ferromanganese oxides and the depleted quantities of active components are calculated ： the depleted quantities of active components for the unit mass of fresh basalts vary in the range of 0.15 ～ 0. 657, and the precipitated quantities of ferromanganese oxides for the unit mass of fresh basahs vary in the range of 0. 006 ～ 0. 042. Of the major elements, the two most depleted are iron, and magnesium, with 18.28% ～ 70.95% of iron and 44.50% ～ 93.94% of magnesium in the fresh basalts was leached out. Theoretical calculation and geochemistry results both indicate that low-temperature alteration of basalts can supply abundant amount of metals to seawater, and may play an important role in ocean metal circulation. 相似文献
11.
12.
13.
每年,每月,甚至每天,世界各地大大小小的选美、选秀和类似活动从没有中断过。这不,今年又有好事者发起了重选世界七大奇迹的活动,咱 相似文献
14.
15.
16.
可能许多读者在孩提时代都问过这样的问题:从我站着的地方一直往下钻个洞,钻到地球那一边,会钻到什么地方呢?实际上,这个问题涉及一个地理学概念:对跖点。所谓对跖点,是指地球上一南一北两个纬度数值相同,而经度相差180°的点(赤道上的点,其对跖点仍在赤道上)。也就是 相似文献
17.
匮乏的证据面对亚特兰蒂斯的各种动人传说,科学家们的态度是谨慎的。如果亚特兰蒂斯真的存在过,那么首先应该在地质学和考古学范畴找到证据。从地质学方面说,如果大西洋中存在过大陆,并因灾变而沉没,那么在大西洋海底应当有相应的沉积物、地形及杂物。从考古学方面说,应当有相应的人工制品;同时,也应该能找到有关语言文字,以及其他属于文化范畴的考古资料。然而,令人遗憾的是,全世界的地质 相似文献
18.
19.
20.
在作者从事我国淡水藻类研究中,积累了一些有关分类学方面的资料。现将这些资料陆续加以整理,写成论文发表。篇幅较短的都编入此《杂录》中。一、在中国发现的绿鞭藻科植物Ⅰ.On Some Species of the Chloromonadaceae Found in China绿鞭藻科(Chloromonadaceae)在分类位置至今尚未确定的绿鞭藻纲(Chloromonadineae)中是最典型的一科,包括具有2条鞭毛和多数盘状色素体的种类。由于这些藻类很不常见,虽然在百年前已有此科种类的记载,但可供参考的文献至今还很少,记载的种类也不多;为一般所公认的也不过3属、共约11种。同时,根据现有的记载,这些种类在地理分 相似文献