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91.
Rats use multiple sources of information to maintain spatial orientation. Although previous work has focused on rats’ use
of environmental cues, a growing number of studies have demonstrated that rats also use self-movement cues to organize navigation.
This review examines the extent that kinematic analysis of naturally occurring behavior has provided insight into processes
that mediate dead-reckoning-based navigation. This work supports a role for separate systems in processing self-movement cues
that converge on the hippocampus. The compass system is involved in deriving directional information from self-movement cues;
whereas, the odometer system is involved in deriving distance information from self-movement cues. The hippocampus functions
similar to a logbook in that outward path unique information from the compass and odometer is used to derive the direction
and distance of a path to the point at which movement was initiated. Finally, home base establishment may function to reset
this system after each excursion and anchor environmental cues to self-movement cues. The combination of natural behaviors
and kinematic analysis has proven to be a robust paradigm to investigate the neural basis of spatial orientation. 相似文献
92.
Liang T Zhang S Wang L Kung HT Wang Y Hu A Ding S 《Environmental geochemistry and health》2005,27(4):301-311
With the continual increase in the utilization of rare earth elements (REEs) for industrial and agricultural purposes in China,
the research into the environmental biogeochemical behavior of REEs has become a pressing issue. The REEs’ content in soil
and various parts of wheat under different conditions in soil–plant systems were measured by INAA and ICP-MS. The results
showed four aspects. (1) The mean value of total REEs in soil of China was 176.8 mg kg−1. The mean ratio of ΣLREE/ΣHREE in soils was 8.0 and cerium accounts for 42% of the total REEs. The content of REEs in wheat
seed ranged between 10−11 and 10−8 g g−1, 3–4 orders of magnitude lower than that in soil. (2) The REEs contents in ryegrass, especially in roots, were significantly
related to that of soil. The bioavailability of REEs in soil mainly depended on the exchangeable fraction of REEs, which was
strongly affected by the physico–chemical properties of the soil. (3) Long-term foliage-dressing with Changle microfertilizer
of REEs did not affect the contents and distribution patterns of REEs in soil. At the maturing stage of spring wheat, the
REEs content was in the order of root > leaf >stem and crust. Compared with the control, foliage-dressing has a higher accumulation
of REEs in root and leaf. However, no significant difference was found in stem and crust between the two treatments. (4) There
was no significant accumulation with the soil-dressing method. When comparing controls in both foliage- and soil-dressing
methods, no distinct residue of REEs in grains was found. 相似文献
93.
贵阳市郊菜园土-辣椒体系中重金属的迁移特征 总被引:10,自引:0,他引:10
选择贵阳市郊二戈寨、马铃乡和永乐乡的辣椒地,研究重金属在菜园土-辣椒体系中的迁移过程.结果表明,二戈寨、马铃乡和永乐乡3处采样地点菜园土中存在不同程度的重金属污染,综合污染指数分别为1.17、1.23和2.18,主要污染元素为Zn、Cu、Cd.但辣椒果实中仅有Cd超标.在土壤-辣椒体系各界面间,重金属元素迁移能力大小顺序发生了变化:在土壤-根部间为CdCu>Zn>Pb,在根部-茎叶间为Zn>Cd>Pb>Cu,在茎叶-果实间为Cu(>>)Zn>Cd>Pb.对于Cu、Pb和Zn元素来说,辣椒根-土界面是重金属进入辣椒果实的主要障碍,其生物富集系数BCF值(蔬菜根中重金属含量/土壤中重金属含量)分别在0.21~0.44、0.04~0.24和0.033~0.08之间,而Cd的BCF值却达1.06~4.23,表现为富集作用.Cd的迁移系数TF1值(蔬菜茎叶中重金属含量/根部重金属含量)表明,其在根部-茎叶间的迁移几乎不受阻碍,但在果实-茎叶界面再次受阻,其TF2值(蔬菜果实中重金属含量/茎叶中重金属含量)在0.42~0.51之间. 相似文献
94.
Yiming Yang Zhongren Nan Zhuanjun Zhao Zhaowei Wang Shengli Wang Xia Wang Wangqiang Jin Cuicui Zhao 《环境科学学报(英文版)》2011,23(8):1368-1374
A pot experiment was conducted to study the bioaccumulation and translocation of cadmium (Cd) in cole (Brassica campestris L.)
and celery (Apium graveolens) grown in the Cd-polluted oasis soil, Northwest of China. The results showed that Cd in the unpolluted
oasis soil was mainly bound to carbonate fraction (F2) and Fe-Mn oxide fraction (F3). However, marked change of Cd fractions was
observed with increasing soil Cd concentrations, in which the concentration of Cd in F1 (exchangeable fraction), F2 and F3 increased
significantly (p < 0.001 for F1, F2 and F3). The growth of cole and celery could be facilitated by low concentrations of Cd, but inhibited
by high concentrations. The correlation analysis between the fraction distribution coefficient of Cd in the soil and Cd concentration
accumulated in the two vegetables showed that Cd in F1 in the soil made the greatest contribution on the accumulation of Cd in the
two vegetables. The high bio-concentration factor and the translocation factor of Cd in both cole and celery were observed, and Cd
had higher accumulation in the edible parts of the two vegetables. Therefore, both cole and celery grown in Cd-polluted oasis soil
have higher risk to human health. And the two vegetables are not suitable to be cultivated as vegetables consumed by human in the
Cd-polluted oasis soil. 相似文献
95.
96.
NaCl胁迫下苋菜中镉的亚细胞分布及转运研究 总被引:2,自引:0,他引:2
中国大面积的农田土壤面临盐渍化和重金属的双重污染。探索盐分胁迫下作物可食部分的重金属累积特征将为保障农产品安全提供科学依据。本文主要从镉的亚细胞分布和离子选择性角度探讨盐分胁迫对苋菜(Amaranthus mangostanus L.)镉转运过程的影响。本试验采用水培苋菜的方式,添加不同质量浓度(0、2.5、5.0、7.5和10.0 g·L-1)NaCl和3.0μg·L-1Cd处理,测定台湾白苋菜(耐盐型)和尖叶青苋菜(敏感型)根、茎、叶中Cd和Ca的亚细胞质量分数变化。Cd的亚细胞组分质量分数由大到小顺序均为:细胞壁(FI)>细胞器(FII)>>细胞液(FIII)。NaCl胁迫下,苋菜根、茎、叶中细胞壁(FI)和细胞器(FII)Cd质量分数总体显著下降,下降幅度为16%~71%,胞液(FIII)Cd质量分数基本不变,这主要和Na的竞争吸附和吸收有关。同时耐盐型台湾白苋菜根细胞器,茎、叶细胞壁和细胞器Ca质量分数总体下降,下降范围为20%~70%。敏感型尖叶青苋菜根、茎细胞壁和细胞器组分Ca质量分数均显著下降,叶细胞壁Ca质量分数下降幅度高达80%,说明细胞壁和质膜的生理结构和组成可能发生了变化;另一方面,苋菜的运输选择性比例TSK. Na(根-茎)、TSCa. Na(根-茎)和TSMg. Na(根-茎)显著下降,下降幅度达50%以上,TSK. Na(茎-叶)、TSCa. Na(茎-叶)和TSMg.Na(茎-叶)相较对照急剧上升,上升幅度均在44%以上,表明苋菜根部K、Ca、Mg向茎转移的选择性减弱;而茎向叶转移的选择性增强。苋菜细胞组成和离子选择性的变化使根、茎中细胞壁和细胞器对Cd的截留能力变差,Cd向地上部转移的比例增大,Cd在苋菜的转运系数TF(根-茎)、TF(茎-叶)较对照处理呈现不同程度的上升。台湾白苋菜的TF(根-茎)大于尖叶青苋菜,而TF(茎-叶)小于尖叶青苋菜,表明敏感型苋菜茎细胞对Cd截留能力较强,而耐盐型苋菜根细胞对Cd的截留能力较强。 相似文献
97.
98.
“不谴责”安全文化的机理与运用 总被引:1,自引:1,他引:0
刘景凯 《中国安全生产科学技术》2011,7(6):87-91
安全生产的形势正在实现持续好转,但因人员违章和不安全行为引发的事故仍未根本杜绝,人因问题成为当今安全管理和文化建设研究一项十分重要的课题。通过行为安全研究和管理体系分析表明,规章制度的完整性、有效性、可操作性及员工的接受能力等因素,都将影响到员工遵章程度和安全行为。不加区分对待和从管理的深层次剖析,对违章和不安全行为一律强调和执行严厉处罚的纪律处理,并不能很好的解决人员违章问题。本文通过对人员行为安全、规章制度建设和管理体系的全面分析,阐述了"不谴责"安全文化建设的工作原理,针对不同的安全管理阶段和工作实际,提出了推行基于"公平和公正"这一"不谴责"安全文化的具体对策,对解决企业当前安全管理工作中所遇到的一些问题,有一定的指导意义。 相似文献
99.
100.
组配改良剂对土壤-蔬菜系统铅镉转运调控的场地研究 总被引:1,自引:1,他引:0
以组配改良剂LS(石灰石∶海泡石=2∶1)为试验材料,通过对湘南某矿区附近铅镉复合污染旱地土壤进行现场改良钝化,研究施加不同量的LS(0、2、4、8 g·kg-1)对茄子和苋菜植株吸收累积Pb和Cd的影响以及对Pb和Cd在2种蔬菜植株各部位间转运的调控.结果表明:1施加LS能够显著提高土壤p H,降低土壤中交换态Pb和Cd的含量.2施加LS能显著降低2种蔬菜植株各部位中Pb和Cd的含量.LS施加量为2~8 g·kg-1时,茄子果实中Pb和Cd的含量分别降低44.7%~78.6%和36.0%~78.7%;苋菜植株茎叶中Pb和Cd的含量分别降低45.8%~59.1%和40.0%~87.2%.3LS的施加降低了2种蔬菜植株各部位间Pb和Cd的转运系数.2种蔬菜植株在根-茎-果实间或根-茎叶间转运Cd的能力大于Pb,且施加LS各处理下,同种蔬菜相同部位对Pb和Cd的转运能力大小关系保持不变. 相似文献