非道路用柴油机半挥发性有机物排放特性

在一台国Ⅱ标准的非道路用柴油机上对半挥发性有机物（SVOCs）进行采样研究发现,非道路用柴油机排放气相SVOCs高于颗粒固相SVOCs,且在两相中的排放量均呈现随负荷增加而增加的趋势在气相和颗粒固相SVOCs中检出以烷烃为主,其次为多环芳烃类物质,包括2,3-二氢茚、四氢化萘、联苯、萘、芴、蒽、菲、芘等及其同系物．同时在对SVOCs中PAHs的研究中发现,柴油机排放的PAHs以气相为主,含量明显高于颗粒固相中PAHs;对比气固两相的浓度分布发现,气相PAHs中萘、苊烯、二氢苊、芴、菲、蒽为主,占气相PAHs质量比高达95％,而颗粒固相中PAHs则以菲、芘、荧蒽、屈、苯并（a）蒽等为主,其中苯并（a）蒽与屈在不同工况下质量比达80％以上;气相中PAHs环数以3环和2环为主,而大部分工况下颗粒固相中PAHs环数以4环为主,其次为3环．     

半挥发性有机污染物的人体暴露评估方法

 半挥发性有机物（SVOCs）的人体暴露研究已成为环境研究领域的热点。传统的人体暴露评估方法（如血液组织检测等）具有侵入性、复杂性、成本高、样品难获得等缺点。新型被动采样方法以其非侵入性、简单易行、易于接受等优点逐渐受到了广泛关注。总结了非饮食人体暴露评估的方法，重点介绍了人体暴露评估的新兴被动采样技术，包括硅胶腕带、硅胶胸针、手擦拭样、衣服等，其中硅胶手环和硅胶胸针以其廉价易得、易于被接受和稳定性好等优点逐渐得到了广泛应用；此外，利用衣服作为SVOCs人体暴露研究的手段，也具有良好的发展潜力和应用前景。     

GC-MS-SIM对宝鸡市饮用水中8种SVOCs的测定

目的 研究建立宝鸡市饮用水源地硝基苯等8种半挥发性有机物（SVOCs）的分析方法,为相关部门决策提供依据.方法 以二氯甲烷液液萃取富集浓缩、TR-5ms非极性柱分离、单四极杆质谱仪检测及选择离子扫描模式测定了宝鸡市饮用水中8种SVOCs（硝基苯、二硝基甲苯、硝基氯苯、邻苯二甲酸二丁酯（（DBP）、邻苯二甲酸二（2-乙基已基）酯（BEHP）、p,p＆#39;-DDT、林丹、阿特拉津）.结果 在选择离子扫描模式下,在0.2～10.0 μg/L范围之内,8种SVOCs的浓度x（μg/L）与其峰面积之间存在良好的线性关系（R≥0.995）;平均回收率在73.35％～95.59％之间,在EPA8270方法中推荐的参考范围内.取样体积为500mL时,检出限在0.16～1.00 μg/L,宝鸡水样分析结果表明,8种SVOCs的含量除林丹外,均低于GB3838-2002检出限;相对标准偏差（RSD）在2.6％～8.6％之间,均在允许偏差之内.结论 液液萃取/GC/MS/SIM方法在线性范围（0.2～10.0μg/L）内,检出限、准确度和精密度表现良好,能够满足饮用水源地水质分析的要求.     

Sn中不含零列的幂等元的性质

给出了随机矩阵半群Sn中的元A是幂等元的充要条件。由于Sn中的幂等元可能含有零列,也可能不含零列,主要对Sn中不含零列的幂等元进行了研究（对含有零列的幂等元另文讨论）,定义了一种新的等价关系,并用这一等价关系给出了E0（Sn）中右零带的结构。     

La—XO和La—XO—CPC体系的导数光谱研究

本文研究了镧－二甲酚橙和橙－氯化十六烷基吡啶两个体系的０－４阶导数光谱并给出最佳仪器参数。结果表明，镧－二甲酚橙体系在ｐＨ为４．００－６．００和ｐＨ〉８．００时可用于分析测定，在ｐＨ为７．００－８．００无吸收光谱；镧－二甲酚橙－氯化十六烷基吡啶在所研究的ｐＨ范围内均可用于分析测定目的。     

The self-aggregation of chiral threonine-linked porphyrins and their zinc(II) complexes

The self-aggregation of chiral threonine-linked porphyrins and their zinc(Ⅱ) complexes in water-alcohol system and water-alcohol-NaCI system has been studied by circular dichroism (CD), UV-Vis absorption spectra and fluorescence spectra methods. The experiment results indicate that chiral threonine-linked porphyrins and their zinc(Ⅱ) complexes have two different kinds of aggregates in water-alcohol system and water-alcohol-NaCI system. And the porphyrins may form highly organized and orientated aggregates in water-alcohol-NaCI system. The aggregates in water-alcohol-NaCI system may have helical structures.     

松科花粉鉴定要点及其生态环境特征研究

通过详细比较认为铁杉属花粉较容易与松科其他属区分;冷杉属、雪松属、云杉属、松属可以从气囊的形状和网眼大小、帽与帽的肌理、本体与气囊的过渡上进行区分;松属2亚属(单束松型、双束松型)植物花粉形态可从花粉在体远极的纹饰及花粉的气囊与体接触面的长度与气囊的直径大小进行区分.对松科5属2亚属的生态环境进行研究认为,松科植物适宜年均温度范围有所不同,特别是双束松型植物适生于平均海拔高度不超过1 200 m的低温、干冷条件下,而单束松型植物适生在平均海拔高度超过1 200 m的温凉、温湿的气候条件下.     

Can transgenic rice cause ecological risks through transgene escape?

Alien transgene escape from genetically engineered rice to non-transgenic varieties or close wild relatives (including weedy rice) may lead to unpredictable ecological risks. However, for transgene escape to occur three conditions need to be met: (i) spatially, transgenic rice and its non-transgenic counterparts or wild relatives should have sympatric distributions; (ii) temporally, the flowering time of transgenic rice and the non-transgenic varieties or wild relatives should overlap; and (iii) biologically, transgenic rice and its wild relative species should have such a sufficiently close relationship that their interspecific hybrids can have normal generative reproduction. This paper presents research data on the geographic distribution, flowering habits, interspecific hybridization, and gene flow of cultivated rice (Oryza sativa) and its closely related wild relatives containing the AA genome. The objective is to estimate the possibility of transgene escape to non-transgenic rice varieties and wild relatives of rice, which may result in unpredictable ecological risks.     

一类非齐次边值问题的正解存在性与不存在性

讨论非齐次边值问题y″=q(t)f(t,y),y(0)=a>0,y′(1)=0.对q(t)f(t,y)0并且q可能在t=0附近,f可能在y=0附近具有奇异性的情形,给出正解的某些存在性与不存在性结论.     

电磁消涡与减震技术研究

利用流体边界层上的电磁体积力控制流体边界层的周期性脱落与分离,限制尾流涡街的产生,从而实现消除涡流和减少涡生震动的目的.理论分析和实验研究表明,当圆柱表面包覆的电磁场作用参数N＞1,包覆磁场强度B≥0.5 T,流体边界层表面电流密度j为103 A/m2数量级时,对于一般情况下的流场参数而言,流体边界层上的电磁体积力具有十分良好的消涡与减震控制作用效果.优化圆柱体表面的电磁场包覆范围,可以提高电磁消涡减震控制效率.当流体边界层上的电磁体积力方向与流体边界层的流动方向相反时,电磁力又具有显著的增涡增震控制作用效果.     

不同Zn、Cu水平对香根草(Vetiveria zizanioides)体内Cd积累及生理指标的影响

采用水培试验研究了不同浓度的重金属Cd(15、30 mg·L-1)污染下,不同浓度Zn、Cu(10、40 mg·L-1)对香根草生长、丙二醛(MDA)含量、根系活力、可溶性蛋白质、叶绿素含量以及香根草体内Cd积累的影响.结果表明,除了低浓度的Cu外,不同浓度的Zn、Cu、Cd对香根草体内生理生化指标都产生协同或加和作用,提高了香根草体内MDA含量,降低了根系活力、叶绿素a、b含量以及可溶性蛋白质含量.Zn、Cu对植物吸收Cd的复合作用较为复杂,其中对香根草地上部Cd的转移可能产生拮抗作用,对根部Cd的吸收可能产生协同或加和作用.     

The self-aggregation of chiral threonine-linked porphyrins and their zinc(Ⅱ) complexes

The self-aggregation of chiral threonine-linked porphyrins and their zinc(Ⅱ) complexes in water-alcohol system and water-alcohol-NaCl system has been studied by circular dichroism (CD),UV-Vis absorption spectra and fluorescence spectra methods.The experiment results indicate that chiral threonine-linked porphyrins and their zinc(Ⅱ) complexes have two different kinds of aggregates in water-alcohol system and water-alcohol-NaCl system.And the porphyrins may form highly organized and orientated aggregates in water-alcohol-NaCl system.The aggregates in water-alcohol-NaCl system may have helical structures.     

新生儿坏死性小肠结肠炎中细胞死亡机制的研究进展

坏死性小肠结肠炎(Necrotizing Enterocolitis, NEC)是由多因素作用导致的肠道急性炎症性疾病,是早产儿主要的死亡原因之一。以往的研究认为,细胞凋亡是NEC中肠上皮细胞最主要的死亡形式。但近年来的研究发现,程序性坏死(Necroptosis)、细胞焦亡(Pyroptosis)及铁死亡(Ferroptosis)等非凋亡形式的程序性细胞死亡(Programmed Cell Death, PCD)也可能参与到NEC的发病机制中,不同形式的细胞死亡的信号调节通路不同,可能会相互影响或存在共同的调节机制如细胞广泛凋亡小体(PANoptosome)等。本文综述了非凋亡形式的不同类型程序性细胞死亡方式及其信号调节通路,以及其在NEC中的作用机制,并提出NEC诊断生物标志物或防治的新靶点,以期为临床NEC的预防和管理提供思路。     

Pre-biotic organic matter from comets and asteroids

Several authors have suggested that comets or carbonaceous asteroids contributed large amounts of organic matter to the primitive Earth, and thus possibly played a vital role in the origin of life. But organic matter cannot survive the extremely high temperatures (>10(4) K) reached on impact, which atomize the projectile and break all chemical bonds. Only fragments small enough to be gently decelerated by the atmosphere--principally meteors of 10(-12)-10(-6) g--can deliver their organic matter intact. The amount of such 'soft-landed' organic carbon can be estimated from data for the infall rate of meteoritic matter. At present rates, only approximately 0.006 g cm-2 intact organic carbon would accumulate in 10(8) yr, but at the higher rates of approximately 4 x 10(9) yr ago, about 20 g cm-2 may have accumulated in the few hundred million years between the last cataclysmic impact and the beginning of life. It may have included some biologically important compounds that did not form by abiotic synthesis on Earth.     

英语中and连接的成对出现的词

英语中and连接的成对出现的词构成的短语相当多,这些短语的基本特点是大都固定不变;在语义上不少并非and前后两词相加,而是起了“化学变化”,在语性上也未必同and前后的词性一致。因此,在英语教学中不可不予以特别关注。     

广东,海南普通野生稻酯酶同工酶的研究

广东,海南普通野生稻５８份样本中酯酯同工酶的酶带数从８到１５条均有,酶谱类型可归纳为１７种类型,相同谱型的酶带种类和数量相同,酶谱相似系数为１,亲缘关系最密切,相似系数０．９以上的植株亦很密切;０．８－０．８９亲缘关系也很近。     

Nuclear magnetic resonance imaging of a single cell

Nuclear magnetic resonance (NMR) imaging is now an established tool in clinical imaging and competes favourably with conventional X-ray computerized tomography (CT) scanning. The drive behind NMR imaging has primarily been in the area of whole-body imaging, which has been limited clinically to fields of up to 1.5 T (60 MHz). It is recognized that there may be substantial advantages in obtaining images with sub-millimetre spatial resolution. Also, there may be benefits to imaging at higher fields, since the signal increases as the square of the magnetic field. Using a modified 9.5 T 89-mm-bore high-resolution NMR spectrometer, we have now obtained the first NMR images of a single cell, demonstrating the advent of the NMR imaging microscope. The NMR microscope is expected to have considerable impact in the areas of biology, medicine and materials science, and may serve as a precursor to obtaining such resolutions on human subjects.     

The Earth's missing lead may not be in the core

Relative to the CI chondrite class of meteorites (widely thought to be the 'building blocks' of the terrestrial planets), the Earth is depleted in volatile elements. For most elements this depletion is thought to be a solar nebular signature, as chondrites show depletions qualitatively similar to that of the Earth. On the other hand, as lead is a volatile element, some Pb may also have been lost after accretion. The unique (206)Pb/(204)Pb and (207)Pb/(204)Pb ratios of the Earth's mantle suggest that some lead was lost about 50 to 130 Myr after Solar System formation. This has commonly been explained by lead lost via the segregation of a sulphide melt to the Earth's core, which assumes that lead has an affinity towards sulphide. Some models, however, have reconciled the Earth's lead deficit with volatilization. Whichever model is preferred, the broad coincidence of U-Pb model ages with the age of the Moon suggests that lead loss may be related to the Moon-forming impact. Here we report partitioning experiments in metal-sulphide-silicate systems. We show that lead is neither siderophile nor chalcophile enough to explain the high U/Pb ratio of the Earth's mantle as being a result of lead pumping to the core. The Earth may have accreted from initially volatile-depleted material, some lead may have been lost to degassing following the Moon-forming giant impact, or a hidden reservoir exists in the deep mantle with lead isotope compositions complementary to upper-mantle values; it is unlikely though that the missing lead resides in the core.     

An African primate lentivirus (SIVsm) closely related to HIV-2

The ancestors of the human immunodeficiency viruses (HIV-1 and HIV-2) may have evolved from a reservoir of African nonhuman primate lentiviruses, termed simian immunodeficiency viruses (SIV). None of the SIV strains characterized so far are closely related to HIV-1. HIV-2, however, is closely related to SIV (SIVmac) isolated from captive rhesus macaques (Macaca mulatta). SIV infection of feral Asian macaques has not been demonstrated by serological surveys. Thus, macaques may have acquired SIV in captivity by cross-species transmission from an SIV-infected African primate. Sooty mangabeys (Cercocebus atys), an African primate species indigenous to West Africa, however, are infected with SIV (SIVsm) both in captivity and in the wild (P. Fultz, personal communication). We have molecularly cloned and sequenced SIVsm and report here that it is closely related to SIVmac and HIV-2. These results suggest that SIVsm has infected macaques in captivity and humans in West Africa and evolved as SIVmac and HIV-2, respectively.