排序方式: 共有107条查询结果,搜索用时 15 毫秒
21.
新乡太行山区木本彩叶植物资源 总被引:4,自引:0,他引:4
概括总结了新乡太行山区的木本彩叶植物资源总量、资源种类、观赏价值和开发潜力,描述了其中几种重要的木本彩叶植物,给新乡木本彩叶植物资源的开发利用提供参考. 相似文献
22.
Cancer is the leading cause of death in China and a significant public health problem with increasing incidence and fatality rates. The Han nationality is the main ethnic group in China, and many reports on the epidemiology of cancers in Han nationality are published. However no studies report the cancer spectrum of Uygurs which are one of the minority nationalities in China. Hence, we present incidence and mortality numbers of different cancers for the Uygur patients for the period 2018–2020 in Hotan District where Uygur population accounts for 99 %. During the 3-year study period, 2509 new Uygur cancer cases were registered, comprising 774 men and 1735 women. Cervical cancer was the most common, followed by esophageal, breast, gastric and colorectal cancers. The most common cancers in women and men were cervical cancer and esophageal cancer, respectively. In conclusion, the cancer spectrum in Hotan is different from other regions of China and our research revealed the cancer incidence in Hotan, which could help us to take appropriate measures to reduce the incidence rate. 相似文献
23.
基于水量平衡下灌区农田系统中氮素迁移及平衡的分析 总被引:3,自引:0,他引:3
本文以于河套灌区典型灌域(前旗北疙堵乡塔布村)为研究对象,通过分析农田系统中水量平衡和氮素平衡,建立农田系统中氮素平衡和水分平衡的联立模型,并用此模型分析典型区域内农田系统中氮素随水分迁移的规律。分析表明:应用水量和氮平衡模型分析灌区农田系统中氮迁移及平衡,可以反映出农业面源污染物(氮)在整个农田系统中的去向,化肥使用量的降低和灌水量的减少,将有效的减少农田系统中氮素的输入量;秋灌—秋浇期间,玉米、番茄和葵花作物对氮的吸收率分别为17%、18%和32%,3种土壤中残留量分别为57%、60%和58%。依据河套灌区年施肥60万t计算,土壤残留量达到17.2万t。在秋灌-秋浇期间从黄河引入的氮总量达到1.21万t,随农田退水进入沟道的量为840 t。 相似文献
24.
利用PHI数据进行区域性植物生理信息探测与分析 总被引:1,自引:0,他引:1
本次试验研究选择两个实验区 :沼泽地和植被茂盛区。利用 2 0 0 0年 9月上旬在黑龙江省大兴安岭地区获取的推帚式超光谱成像 ,(PHI,pushbroomhyperspectralimager)数据进行区域性植物生理量 (主要是叶绿素 )的探测与生态分析。在叶绿素含量探测中 ,结合所获取的成像光谱PHI数据的特点 ,在比较不同技术方法的基础之上 ,选用了有效而简单可靠的RARS(Ratioanalysisofreflectancespectra)指数。该色素指数与植物叶绿素a、b含量拟合的相关系数 (R)达 0 .8以上。利用PHI数据和野外实测植物光谱分别建立沼泽地和植被茂盛区的RARS指数模式 ,分别得到具有指示两试验区的叶绿素a (Chla)、叶绿素b (Chlb)以及类胡萝卜素 (Cars)的参数图像。更进一步地利用Blackburn(1998)所建立的RARS指数与叶绿素浓度之间的强拟合方程 ,相对定量估算了叶绿素a、b浓度的区域性分布 ,清晰地反映出植被生态状况和差异。这与野外实地考察较为一致。 相似文献
25.
Griselda Margarita Rodríguez-Figueroa Evgueni Shumilin Ignacio Sánchez-Rodríguez 《Journal of applied phycology》2009,21(1):19-26
The coastal marine sediments near Santa Rosalía on the eastern coast of the Baja California Peninsula (Mexico) are heavily
polluted by metals due to copper mining and smelting over the past century (up to 1984). The present study compares the accumulation
of metals in the brown seaweed Padina durvillaei from the central segment of the coast of Santa Rosalía (polluted by Co, Cu, Mn and Zn) and from two segments north and south
of the known “hot spot”. The seaweed samples were collected in May and August 2004 and June 2005 at 13 stations located along
the Santa Rosalía mining region. Heavy metal concentrations were measured by instrumental neutron activation analysis (Co
and Fe) directly in dried homogenized subsamples or by flame atomic absorption spectrophotometry (Cd, Cu, Mn, Ni, Pb and Zn)
after complete strong acid digestion of sub-samples. The means and standard deviations of the concentrations in dry tissues
of Padina durvillaei specimens for all the studied metals and stations lie in the following sequence: Cd (3.6 ± 1.6 mg kg−1) < Co (6.5 ± 6.1 mg kg−1) < Pb (7.8 ± 6.2) < Ni (9.96 ± 5.28 mg kg−1) < Cu (53 ± 38 mg kg−1) < Zn (63 ± 43 mg kg−1) < Mn (295 ± 269 mg kg−1) < Fe (2243 ± 2325 mg kg−1). This increase of the average concentrations was statistically significant. Principal Component Analysis showed that Factor
1 (36.46%) displays high positive loadings for Co, Cu, Mn and Zn, reflecting the influence of local anthropogenic pollution
on the seaweed composition, while Factor 2 (26.91%) is important for Co, Fe and Ni and probably corresponds to the adsorption
or accumulation of terrigenous elements of the regional origin, while Factor 3, with a high positive loading for Pb and a
high negative loading for Cd, is probably controlled by local and regional anthropogenic input of Pb and episodic supply of
Cd by local upwellings. The results of ANOVA for each element do not show any significant differences between the average
concentrations for Cd, Fe, Ni and Pb in the seaweed of the three segments, or between the central and southern segments for
Cu, Mn and Zn. Cobalt contents in the seaweed from the northern and central segments are, however, significantly different
from the southern segment. This indicates that element concentrations in Padina durvillaei generally do not follow the drastic increases and gradients of Cu, Co, Mn and Zn contents detected in surface sediments.
The apparent contradiction could be explained by a low geochemical mobility of these metals in the polluted sediments, composed
mainly of stable residues of smelter wastes, with very low content of organic matter usually driving diagenetic mobilization
of some metals into interstitial waters and then to the overlying water. 相似文献
26.
常州地区蝶类资源及区系组成 总被引:6,自引:0,他引:6
在1991~2002年间,笔者对江苏常州地区蠊类资源进行了调查,共采集到蠊类64种(或亚种),隶属于8科46属。其中古北种14种,东洋种10种,古北—东洋共有种37种,广布种3种,分别占总数的21.9%、15.6%、57.8%和4.7%,表明该地区蝴蝶以古北、东洋混生种类为主要成份,并且有由古北区向东洋区过渡的特征。同时还记述了各种蝴蝶的学名和寄主。调查还发现江苏省新记录1属10种. 相似文献
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28.
目的:调查与分析遂宁地区良性前列腺增生术后下尿路症状(Lower Urinary Tract Symptoms,LUTS)发生的相关危险因素。方法:2014年9月到2019年10月选择在遂宁市中心医院诊治的遂宁地区良性前列腺增生症患者172例,所有患者都给予手术治疗,记录术后LUTS发生情况,调查患者的临床资料并进行影响因素分析。结果:在172例患者中,术后平均国际前列腺症状评分量表(International prostate symptom scores,IPSS)评分为5.67±0.13分,其中储尿期症状评分3.01±0.11分,排尿期症状评分为1.76±0.22分,排尿后症状评分0.89±0.14分,发生LUTS 18例(LUTS组),发生率为10.5%。LUTS组的生活质量评分高于非LUTS组(P<0.05);LUTS组的年龄、体重指数、低密度脂蛋白、总胆固醇、前列腺体积与非LUTS组对比差异有统计学意义(P<0.05);Pearson分析显示年龄、体重指数、低密度脂蛋白、总胆固醇、前列腺体积都与LUTS存在相关性(P<0.05);二元Logistic回归分析显示年龄、体重指数、低密度脂蛋白、总胆固醇、前列腺体积都为导致LUTS发生的主要因素(P<0.05)。结论:遂宁地区良性前列腺增生术后LUTS的发生比较常见,可严重影响患者的生活质量,年龄、体重指数、低密度脂蛋白、总胆固醇、前列腺体积都为导致LUTS发生的主要因素。 相似文献
29.
从植物形态结构—功能—植物功能群的角度,采用PCA分析、RDA排序和聚类分析法分析了植物叶片形态特征与持水能力的关系,划分了叶片持水功能群。结果表明:决定植物叶片持水能力的主要形态指标为叶片大小、叶片宽窄、叶片粗糙度,据此,评价了贵州茅台水源功能区植物群落中31个主要树种的叶片持水能力,并划分为6个叶片持水功能群:大叶窄叶中粗糙度高持水功能群(PFGsⅠ)、中叶窄叶高粗糙度高持水功能群(PFGsⅡ)、中叶宽叶高粗糙度中持水功能群(PFGsⅢ)、小叶窄叶低粗糙度中持水功能群(PFGsⅣ)、中叶宽叶低粗糙度中持水功能群(PFGsⅤ)、中叶常叶低粗糙度低持水功能群(PFGsⅥ),并描述了各叶片持水功能群的基本特征。 相似文献
30.
预测陕西洛惠渠灌区地下水动态变化情况,在综合分析了各种地下水动态研究方法的基础上,提出了基于支持向量机和改进的BP神经网络模型的灌区地下水动态预测方法,并在MATLAB中编制了相应的计算机程序,建立了相应的地下水动态预测模型。以灌区多年实例数据为学习样本和测试样本,比较了两种模型的地下水动态预测优劣性。研究表明,支持向量机模型和BP网络模型在样本训练学习过程中都具较高的模拟精度,而在样本学习阶段,支持向量机的预测精度明显优于BP网络,可以很好的描述地下水动态复杂的耦合关系。支持向量机方法切实可行,更加适合大型灌区地下水动态预测,是对传统地下水动态研究方法的补充与完善。 相似文献