嘉陵江是长江举足轻重的一条支流,是沿岸地区融入长江经济带的纽带,也是沿岸城市发展和居民生活必不可少的生态资源。因此,嘉陵江生态环境的研究受到了广大学者的关注。文章检索了中国知网(CNKI)数据库和Web of Science(WOS)核心数据库...嘉陵江是长江举足轻重的一条支流,是沿岸地区融入长江经济带的纽带,也是沿岸城市发展和居民生活必不可少的生态资源。因此,嘉陵江生态环境的研究受到了广大学者的关注。文章检索了中国知网(CNKI)数据库和Web of Science(WOS)核心数据库关于嘉陵江生态环境研究的论文,分别得到了347篇和62篇,利用CiteSpace软件进行可视化分析,从发文量、核心作者、主要机构和关键词等方面进行了探讨。结果表明:随着时间发展,发文量总体呈上升趋势,在2021年达到最高;论文发表的主要机构是西华师范大学、西南大学和重庆大学。CNKI数据库(1979—2021)中显示,研究区域主要分为嘉陵江上游、中游和下游地区,研究主题集中在植被的本底调查、水质条件、评价等方面;WOS数据库最近10年(2011—2021)的论文可分为三大类,第一类是对生物(主要是鱼类)的研究,第二类是对污染的研究,第三类是研究方法;大量生态模型以及3S技术被应用在嘉陵江流域的研究中,研究主题主要是风险评价、污染等方面。同时结合2个数据库的结果发现,学者们都重点关注嘉陵江水质条件和评价等方面,并研究了嘉陵江对三峡库区水环境的影响。在当前国家高度重视生态环境保护及重点关注长江经济带发展的大背景下,文章为未来对于嘉陵江流域的研究提出了一些研究方向。展开更多
目的了解太原市学龄前儿童的幽门螺杆菌感染(Helicobacter pylori,HP)状况,及其克拉霉素耐药率,为儿童HP感染预防提供依据。方法采用粪便核酸扩增的方法,抽查太原市南北两所幼儿园120名学龄前儿童,对其粪便标本进行Real time PCR扩增,...目的了解太原市学龄前儿童的幽门螺杆菌感染(Helicobacter pylori,HP)状况,及其克拉霉素耐药率,为儿童HP感染预防提供依据。方法采用粪便核酸扩增的方法,抽查太原市南北两所幼儿园120名学龄前儿童,对其粪便标本进行Real time PCR扩增,并对阳性者克拉霉素耐药基因23S rDNA进行扩增。结果120名学龄儿童粪便标本共有22例HP阳性,阳性率为18.33%,其中有8例为克拉霉素耐药,耐药率为36.36%。结论太原市学龄前儿童HP感染率与全国持平,并且具有较高的克拉霉素耐药率。展开更多
Non-metallic inclusion distribution in the surface layer of IF steel slabs during unsteady casting was investigated using the original position statistic distribution analysis（OPA）method.It was found that most non-m...Non-metallic inclusion distribution in the surface layer of IF steel slabs during unsteady casting was investigated using the original position statistic distribution analysis（OPA）method.It was found that most non-metallic inclusions larger than 10 μm existed in the subsurface layers of 0.5-3.5 mm from the slab surfaces and very few large non-metallic inclusions were found in the inner regions（≥4.5 mm from slab surfaces）.In addition,it was found that at high casting speed level（1.4 m/min）,even a slight change of casting speed could result in a remarkable increase of the non-metallic inclusions.Thus,at high casting speed,changing the casting speed should be avoided or considerably lower speed changing rate must be used.展开更多
The influences of casting speed variation on surface fluctuation of the molten steel in mold during continuous casting were investigated with numerical simulation method.It was found that when the casting speed was ev...The influences of casting speed variation on surface fluctuation of the molten steel in mold during continuous casting were investigated with numerical simulation method.It was found that when the casting speed was evenly decreased from 1.4 m·min-1 to 0.6 m·min-1,the increase of the surface fluctuation of the molten steel in mold was observed only on time that was at the start of casting speed change.While,in experiment of increasing casting speed evenly from 0.6 m·min-1 to 1.4 m·min-1,the increase of the surface fluctuation of the molten steel in mold was observed only at the time when the casting speed was stopped to increase after it had been increased to 1.4 m·min-1.For surface fluctuation of the molten steel in mold which was produced during the casting speed evenly increasing or decreasing period and at the time when increasing or decreasing the casting speed at low casting speed level（0.6 m·min-1）,the influence of casting speed change is very small.In addition,it is found that,at high casting speed level（1.4 m·min-1）,even a little change of casting speed could result in remarkable increase of the surface fluctuation.Thus,at high casting speed,changing casting speed should be avoided or much slower speed changing rate should be used.展开更多
文摘嘉陵江是长江举足轻重的一条支流,是沿岸地区融入长江经济带的纽带,也是沿岸城市发展和居民生活必不可少的生态资源。因此,嘉陵江生态环境的研究受到了广大学者的关注。文章检索了中国知网(CNKI)数据库和Web of Science(WOS)核心数据库关于嘉陵江生态环境研究的论文,分别得到了347篇和62篇,利用CiteSpace软件进行可视化分析,从发文量、核心作者、主要机构和关键词等方面进行了探讨。结果表明:随着时间发展,发文量总体呈上升趋势,在2021年达到最高;论文发表的主要机构是西华师范大学、西南大学和重庆大学。CNKI数据库(1979—2021)中显示,研究区域主要分为嘉陵江上游、中游和下游地区,研究主题集中在植被的本底调查、水质条件、评价等方面;WOS数据库最近10年(2011—2021)的论文可分为三大类,第一类是对生物(主要是鱼类)的研究,第二类是对污染的研究,第三类是研究方法;大量生态模型以及3S技术被应用在嘉陵江流域的研究中,研究主题主要是风险评价、污染等方面。同时结合2个数据库的结果发现,学者们都重点关注嘉陵江水质条件和评价等方面,并研究了嘉陵江对三峡库区水环境的影响。在当前国家高度重视生态环境保护及重点关注长江经济带发展的大背景下,文章为未来对于嘉陵江流域的研究提出了一些研究方向。
文摘目的了解太原市学龄前儿童的幽门螺杆菌感染(Helicobacter pylori,HP)状况,及其克拉霉素耐药率,为儿童HP感染预防提供依据。方法采用粪便核酸扩增的方法,抽查太原市南北两所幼儿园120名学龄前儿童,对其粪便标本进行Real time PCR扩增,并对阳性者克拉霉素耐药基因23S rDNA进行扩增。结果120名学龄儿童粪便标本共有22例HP阳性,阳性率为18.33%,其中有8例为克拉霉素耐药,耐药率为36.36%。结论太原市学龄前儿童HP感染率与全国持平,并且具有较高的克拉霉素耐药率。
文摘Non-metallic inclusion distribution in the surface layer of IF steel slabs during unsteady casting was investigated using the original position statistic distribution analysis（OPA）method.It was found that most non-metallic inclusions larger than 10 μm existed in the subsurface layers of 0.5-3.5 mm from the slab surfaces and very few large non-metallic inclusions were found in the inner regions（≥4.5 mm from slab surfaces）.In addition,it was found that at high casting speed level（1.4 m/min）,even a slight change of casting speed could result in a remarkable increase of the non-metallic inclusions.Thus,at high casting speed,changing the casting speed should be avoided or considerably lower speed changing rate must be used.
文摘The influences of casting speed variation on surface fluctuation of the molten steel in mold during continuous casting were investigated with numerical simulation method.It was found that when the casting speed was evenly decreased from 1.4 m·min-1 to 0.6 m·min-1,the increase of the surface fluctuation of the molten steel in mold was observed only on time that was at the start of casting speed change.While,in experiment of increasing casting speed evenly from 0.6 m·min-1 to 1.4 m·min-1,the increase of the surface fluctuation of the molten steel in mold was observed only at the time when the casting speed was stopped to increase after it had been increased to 1.4 m·min-1.For surface fluctuation of the molten steel in mold which was produced during the casting speed evenly increasing or decreasing period and at the time when increasing or decreasing the casting speed at low casting speed level（0.6 m·min-1）,the influence of casting speed change is very small.In addition,it is found that,at high casting speed level（1.4 m·min-1）,even a little change of casting speed could result in remarkable increase of the surface fluctuation.Thus,at high casting speed,changing casting speed should be avoided or much slower speed changing rate should be used.
