Familial marker chromosome due to 3:1 Disjunction of t(9;15) in a grandparent

An extra small chromosome detected in amniotic fluid was identified as the product of a translocation [46,XX,t(9;15)(p24;q11.2)]. This case is unusual in that individuals with the unbalanced karyotype resulting from a 3:1 disjunction are phenotypically normal.     

Effect of P fertilizer application on N balance of soybean crop in the guinea savanna of Nigeria

Soybean (Glycine max (L.) Merr.) is becoming increasingly important in the cereal-based cropping system of the Nigerian Guinea savanna zone and this justifies research on its effects on soil N. Although soybean can obtain 50% or more of its N requirement from the atmosphere, the N contribution of the crop to the system depends on the amount of N contained in roots, haulms, and fallen leaves after grain harvest. At four sites in the northern Guinea savanna, the effects on N balance of P fertilizer and soybean varieties of different duration were tested. The varieties received P fertilizer at the rates of 0, 30, and 60 kg P ha⁻¹. The total N accumulated aboveground at harvest averaged 104 kg N ha⁻¹ in the early and medium varieties, and 135 kg N ha⁻¹ in the late varieties. Across all varieties and sites, total N content was increased by 40–47% when P was applied. Apparent N harvest index averaged 85% but was not significantly affected by variety or P rate. When only grain was exported, the calculated N balance of the early and the medium varieties was −2.6 to −12.2 kg N ha⁻¹ while the longer duration varieties had positive N balances ranging from 2 to 10.9 kg N ha⁻¹. The N accrual was negative when P was not applied and ranged from 2.4 to 5.2 kg N ha⁻¹ with P application. The interaction of variety and site on the N balance was significant at P<0.05. N balance at the southernmost site was −14.2 kg N ha⁻¹ compared with 2.6–10 kg N ha⁻¹ at the northern sites where N₂ fixation was higher. The estimate of N balance is reduced when soybean haulms are exported. A positive N contribution by soybean is, therefore, possible in a soybean–cereal rotation when: (i) P is applied, (ii) the soybean variety is late maturing, and (iii) only grain is exported.     

长白山阔叶红松林空气N_2O浓度的垂直分布特征

在原始阔叶红松林测定空气N2 O的垂直分布 ,三次观测结果发现林冠高度处N2 O浓度比树干和林冠上方的背景值高 5 4 3% -74 % ,差异极显著。林冠外出现高浓度 ,树干处低浓度 ,表明N2 O是从林冠排放到周围空气中的。因此 ,本研究提供了植物在自然状态下能排放N2 O的证据 ,从而证明了森林生态系统中植物本身也是大气N2 O的排放源。     

大气N_2O的稳定氮同位素质量平衡探讨

地表释放源释放的N2 O均比对流层大气N2 O贫15N ,对流层N2 O的氮同位素质量由平流层回流的富15N的N2 O来平衡 ,若全球N2 O源汇质量估算结果是平衡的 ,则地表释放源对对流层N2 O的氮同位素质量的贡献量应与平流层回流的贡献量相等。本文根据全球N2 O释放源最近的年释放量估算值 ,在考虑土壤N2 O生成过程中的氮同位素分馏效应后 ,推论出全球N2 O释放源最近的年释放量估算值能使对流层大气N2 O稳定氮同位素质量接近于平衡。     

MBBR泥膜复合系统泥膜竞争关系的影响因素

为探究MBBR泥膜复合硝化系统内泥膜竞争关系，通过小试试验研究了水处理过程中常规因素（污泥浓度、DO、温度、C/N）对MBBR泥膜复合系统硝化效果的影响，分析了系统内污泥容积负荷和移动床生物膜反应器（MBBR，Moving-Bed Biofilm Reactor）生物膜容积负荷变化趋势，进而得出泥膜竞争规律.结果表明，MBBR泥膜复合系统容积负荷均大于单一污泥或MBBR生物膜系统的容积负荷.在一定范围内，污泥浓度、DO、温度与MBBR泥膜复合系统容积负荷呈现正相关，且系统内活性污泥在与MBBR生物膜在竞争DO和基质时优势明显，而MBBR生物膜则具有更强的耐低温能力.进水C/N与MBBR泥膜复合系统硝化负荷呈负相关，且活性污泥在应对进水C/N过高时较MBBR生物膜更具优势，MBBR的“镶嵌”则强化了系统SND效果.微生物群落变化显示MBBR泥膜复合系统内的硝化细菌优势菌属为Nitrospira，且悬浮载体生物膜对其富集能力明显高于活性污泥.     

概论N_2O大气浓度演变及其大气化学

N2 O在对流层中是长寿命的痕量温室气体 ;在平流层 ,它是破坏O3层主要痕量气体之一NO的生成源。本文主要综述了N2 O的大气浓度演变、大气寿命、对温室效应的贡献、大气化学等 ,着重探讨了可能存在的N2 O大气生成和消耗过程     

Fate of pesticide N'' (2,4 dimethylphenyl) N methylformamide hydrochloride in simulated aquatic ecosystem

ＦａｔｅｏｆｐｅｓｔｉｃｉｄｅＮ’（２，４ｄｉｍｅｔｈｙｌｐｈｅｎｙｌ）ＮｍｅｔｈｙｌｆｏｒｍａｍｉｄｅｈｙｄｒｏｃｈｌｏｒｉｄｅｉｎｓｉｍｕｌａｔｅｄａｑｕａｔｉｃｅｃｏｓｙｓｔｅｍＹａｎｇＫｅｗｕ，ＭｏＨａｎｈｏｎｇ，ＡｎＦｅｎｇｃｈｕ...     

放牧对草原十壤N2O产生及微生物的影响

利用AIM乙炔抑制法 ,首次测试了我国内蒙古放牧和非放牧羊草草原土壤N2 O产生的微生物过程 ;通过分析不同类型草原土壤N2 O产生的微生物过程和相关微生物菌群的季节变化 ,研究了放牧行为对于草原土壤N2 O微生物产生过程的影响 .放牧行为改变了土壤结构 ,有利于土壤微生物反硝化作用的发生 ,在一定程度上降低了草原土壤N2 O的排放 .揭示了内蒙古草原土壤N2 O产生是以异养硝化作用过程为主的微生物过程 ,解释了内蒙古典型草原土壤N2 O通量较低和其季节变化的微生物学机理     

不同氧化还原电位条件下稻田土壤中15N标记硝态氮的反硝化作用

氧化还原状况是影响土壤中反硝化作用的主要环境因子之一通过不同氧化还原条件下１５Ｎ标记硝态氮反硝化作用的培养试验，结合１５Ｎ气态损失的直接测定方法．研究了反硝化作用发生的氧化还原条件，可为进一步阐明稻田土壤中硝化－反硝化作用氮素损失发生机制提供直接依据．结果表明，氧化和还原条件下均能进行硝态氮的反硝化作用；在４周的培养试验期间，直接测得的氧化（Ｅｈ－２９０－３３０ｍＶ）和还原（Ｅｈ－１１４－４２ｍＶ）条件下的１５Ｎ气态损失分别占加入量的６０．２３±８．０４％和８３．８９±４．７９％．但是，氧化条件下反硝化作用速率明显减缓，外加的硝态氮的半衰期延长，显示了溶解Ｑ２对反硝化作用的抑制作用对反硝化作用进程的模型研究表明速率常数及相应的半衰期作为土壤反硝化作用潜在能力的衡量指标可能优于传统的土壤反硝化势表征方法（反硝化作用百分率），而１５Ｎ示踪－质谱计法直接测定与模型研究相结合则有可能对土壤及其他环境中的反硝化作用作出更恰当的评价．     

稀盐酸溶液吸收—气相色谱法测定环境空气中的痕量三乙胺

以稀盐酸为吸收液，用气相色谱法测定环境空气中痕量三乙胺，结果表明0．1mol／LHCL和0．2mol／LHCL是环境空气中痕量三乙胺的有效吸收液，吸收后样品稳定性良好。在优化的色谱条件下，气相色谱直接进样，FID检测器测定吸收液中的三乙胺线性好、操作简便、精密度高、检出限低，回收率符合要求。