长期施肥对农田黑土微生物群落的影响

研究不同磷肥处理农田黑土基本理化性质、磷脂脂肪酸、酸（碱）性磷酸酶、微生物量碳或氮等变化规律。结果表明,有机肥-化肥配施明显提高土壤有机质、总氮以及速效氮、磷、钾等养分含量,进而促进微生物量碳、微生物量碳/有机质比值、磷酸酶活力以及各菌群磷脂脂肪酸含量显著增加。长期氮磷钾配施土壤有机质活性严重退化、不利于土壤微生物生长,而单施磷肥或氮磷肥配施对微生物活力与结构影响较小。有机肥处理中单烯不饱和/饱和脂肪酸比值>1,远高于其他化肥处理,可用来指示有机质质量与可用性;而支链/单烯不饱和脂肪酸与单烯不饱和/饱和脂肪酸比值呈极显著负相关,表明G+菌对养分胁迫抗性强于G-菌。磷脂脂肪酸PCA表明,有机肥与化肥处理微生物群落结构显著不同。个别脂肪酸载荷值分析表明,真菌受无机肥施用影响显著;而G+菌更易受有机肥影响。     

布久乡农田土壤养分现状及合理施肥对策

通过对布久乡农田土壤养分分析化验，得出一些土壤肥力的结果，并进行评价；同时结合该乡土壤质地和平衡施肥的原理，提出目前布久乡农业生产中合理施肥对策。     

察隅县“3414”玉米测土配方施肥田间肥效试验分析

为了贯彻落实中央1号文件和农业部《关于开展测土配方施肥,大力推广科学施肥的紧急通知》精神,按照自治区农牧厅在山南地区召开的全区测土配方施肥工作会议的具体部署,2007年我县承担了国家测土配方施肥项目,为获得玉米的最佳施肥量和土壤供肥能力及作物养分吸收量等基本参数,为肥料配方提供科学依据。     

长期不同施肥下新疆灰漠土有机碳储量演变分析

新疆灰漠土耕地面积176万hm²,为新疆农业的发展起关键支撑作用。本研究基于新疆灰漠土农田肥力长期监测试验,选择其中不施肥、施化肥和化肥配施有机肥、秸秆的六个处理,对不同施肥处理下土壤表层（0~20cm）和亚表层（20~40cm）土壤碳储量变化特征进行了研究。结果表明：长期不施肥或施用化肥、有机肥均能提高灰漠土表层和亚表层土壤有机碳储量,其中表层土壤有机碳储量提高（4.0~43.7）tC/hm²;亚表层土壤有机碳储量提高（9.0~49.5）tC/hm²。采用不同施肥措施,土壤有机碳储量累积存在时段差异,不施肥耗竭种植条件下在试验初始5年碳储量缓慢下降,但在其后的18年中逐渐升高,因此在肥力水平较低土壤上,即使不施肥但长期耕作也将提高土壤碳储量,有利于贫瘠土壤固碳。这一结果也表明,若采用短期试验观测的数据不能全面反映人为管理措施对土壤碳储量的长期影响,对于碳储量的研究适宜依托长期观测试验的平台来完成。与不施肥或长期施用化肥相比,采用有机无机配施使灰漠土有机碳碳储量提高了32.1%~152.7%,固碳效应显著。将分层土壤容重考虑在内的等质量土壤碳储量计算方法能够较为客观评估秸秆还田的固碳效应。     

Digital transformation during a lockdown

These are indeed exceptional and historic times, a global pandemic and public health emergency sitting side by side with heightened public awareness of the injustices of decades of institutional racism. This article considers the current pandemic and lockdown period through a VUCA lens and offers reflection on how the pandemic revealed the fragility of digitally immature organisations. VUCA, a managerial catchall acronym for Volatility, Uncertainty, Complexity and Ambiguity is a litmus test for recognising unpredictable external environments. We offer business leaders a caveat, it is dangerous to ignore the impact of VUCA on the smooth functioning of an organisation. In terms of digital transformation during lockdown this article offers three key lessons that can so far be discerned from the pandemic period, firstly organisations must improve their digital maturity, secondly, less digitally mature organisations are more fragile and finally organisations with higher levels of digital maturity are generally more flexible.     

Metabolic alterations during Ramadan fast

Some biochemical parameters in 12 young Muslim students who underwent fasting during the entire one month period of Ramadan were investigated. There was a significant reduction in their body weight (72.5±4.0 to 69.4±3.0 kg) and blood glucose levels (99.6±3.5 to 82.9±7.3 mg/dl). Though the morning plasma cortisol fell (215.2±22.1 to 105±11.2 μg/l) and the evening plasma cortisol rose (58.4±5.1 to 64.4±4.8 μg/l) significantly there was no reversal of the circadian rhythm of cortisol secretion. A decline in the diastolic blood pressure (80 to 75±6 of Hg) of these individuals though not significant was also noted. However, cholesterol (160.9±12.8 to 178.2±40.6 mg/dl) and HDL-Cholesterol (42.6±2.2 to 48.1±2.4 mg/dl) showed a tendency for increase. All the changed values were within the normal range.     

Multitasking during Web search sessions

A user’s single session with a Web search engine or information retrieval (IR) system may consist of seeking information on single or multiple topics, and switch between tasks or multitasking information behavior. Most Web search sessions consist of two queries of approximately two words. However, some Web search sessions consist of three or more queries. We present findings from two studies. First, a study of two-query search sessions on the AltaVista Web search engine, and second, a study of three or more query search sessions on the AltaVista Web search engine. We examine the degree of multitasking search and information task switching during these two sets of AltaVista Web search sessions. A sample of two-query and three or more query sessions were filtered from AltaVista transaction logs from 2002 and qualitatively analyzed. Sessions ranged in duration from less than a minute to a few hours. Findings include: (1) 81% of two-query sessions included multiple topics, (2) 91.3% of three or more query sessions included multiple topics, (3) there are a broad variety of topics in multitasking search sessions, and (4) three or more query sessions sometimes contained frequent topic changes. Multitasking is found to be a growing element in Web searching. This paper proposes an approach to interactive information retrieval (IR) contextually within a multitasking framework. The implications of our findings for Web design and further research are discussed.     

期间核查的实施及判定方法

期间核查是对校准实验室和检测实验室的通用要求之一,计量标准的核查关系到该地区计量活动和检测结果的有效性和准确性。期间核查的本质是保持被核查仪器的校准状态,即核查其稳定性。文章讨论期间核查如何实施以及几种实用的期间核查方法。     

企业成长与公司创业精神的培育

创业型企业在现代经济中发挥着越来越重要的作用,关于创业和公司创业精神的研究热潮正悄然兴起。本文从公司创业精神(corporate entrepreneurship)这个概念出发,对公司创业精神及其维度做了一个界定,指出影响公司创业精神的内外环境因素、个体特质及培育公司创业精神的策略,最后,提出培育创业精神对我国企业发展的实践意义。     

北京市冬季大气颗粒物污染水平和影响因素研究

北京市大气颗粒物造成的城市空气污染仍是目前亟待解决的问题之一。为了分析北京市大气颗粒物的污染水平及其影响因素，作者以大气中的PM10 和PM2.5为研究对象，于2005年冬季在北京市范围内设立了5个功能区（9个采样点）进行采样监测。结果表明，北京市PM10 和PM2.5污染比较严重，不同区域的PM10 和PM2.5的污染程度为：交通干道区＞工业区，郊区＞商业区＞居民区，且PM2.5质量浓度的空间分布并不完全同于PM10；气象条件稳定时，PM10 和PM2.5质量浓度的日变化表现出一定的规律性，这种时间变化的特征主要取决于所在环境中排放的污染物变化情况；PM10 和PM2.5的污染程度受气象条件的影响：在一定的范围内，颗粒物质量浓度随着温度的上升而下降，随着相对湿度的升高而增加，随着风力的增强而降低，随逆温层的生成及增强而增高。     

企业创新过程中的知识管理导向

知识管理的导向问题是企业创新绩效和价值创造的决定性因素之一，也是企业创新过程管理面临的重要问题。针对这一问题，本文采取定性与定量相结合的方法，分析了知识管理导向与创新绩效的关系，并从知识管理的角度考察了企业创新过程的三个阶段，在此基础上，通过对不同阶段知识管理导向的比较分析，提出企业应当将技术绩效导向作为创新过程中知识管理的中心环节。     

浅谈课程改革过程中的大学生心理健康教育

大学生心理健康教育对大学生自身成长和高校教育的发展具有重要意义。本文拟从课程改革的理念、方式和制度方面探讨大学生心理健康教育课程的改革,对提高大学生心理健康教育课程的质量有一定的意义。