共查询到20条相似文献，搜索用时 31 毫秒
1.
北安气候变化特征分析及其对农业生产的影响 总被引：1，自引：0，他引：1
根据黑龙江省北安市1959～2009年气温和降水量资料,对北安市近50年的气候变化特征进行分析。结果表明,近50年来北安市年平均气温呈上升趋势,以冬季增温最为明显,春季增温次之,则夏、秋季的变化趋势并不明显。从年降水的长期变化趋势看,降水量略呈现下降趋势,年降水量大小存在波动变化,有一个3-5年的变化周期,近10年平均降水量比50年平均减少39.9mm。分析了气候变化对北安农作物生长发育、养分吸收、产量形成等的影响,提出了调整种植结构、调整种植品种,适时提前播种等农业气象建议、措施,为北安农业生产顺应气候变化提供依据。 相似文献
2.
1951—2009年乌鲁木齐市气候变化特征分析 总被引：3，自引：2，他引：1
利用乌鲁木齐市1951—2009年的地面观测资料,分析了近20年和近10年以来气候变化,并提出了建议,以供参考。 相似文献
3.
[目的]研究近48年沈阳最长连续降水日数的变化特征。[方法]利用1961~2008年沈阳5~9月最长连续降水日数资料,采用一元线性趋势估计和小波分析法,对近48年沈阳最长连续降水日数的变化特征进行分析。[结果]近48年来,除6月最长连续降水日数呈增加趋势外,其他月份均呈下降趋势;最长连续降水日总数呈下降趋势,最大值出现在1986年,最小值出现在1997年;最长连续降水日总数存在着2~3年的周期,1980年以后还并存着5~7年的周期;从20世纪60年代初到90年代中期,最长连续降水日总数为偏多期,其后为偏少期。[结论]该研究为深入了解沈阳的气候变化特征提供了理论依据。 相似文献
4.
近50年塔城盆地日照时数变化特征分析 总被引：2，自引：0，他引：2
[目的]研究近50年塔城盆地日照时数变化特征。[方法]利用塔城盆地4个气象观测站1960～2009年实测年、季、月日照时数资料,采用一元线性回归分析方法,研究了近50年塔城盆地日照时数年、季、月变化的基本特征。[结果]近50年塔城盆地年均日照时数均在2800.0h以上,其中塔城、裕民最多,分别为2936.1、2921.3h,额敏最少,为2814.2h。各站7、8月日照时数最多,6、5月次之,9、4月居第3,12月为全年最少。四季中以秋季、夏季日照时数最多,其次为冬季,春季最少;生长季日照时数以塔城、裕民最多,额敏次之,托里最少。2月4站日照时数线性倾向率均为负值,但仅塔城、额敏以-4.7、-6.0h/10a的速率显著减少;5、6、10月4站日照时数线性倾向率均为正值,但仅裕民站以14.5、12.6、11.2h/10a的速率显著增多。年、生长季日照时数线性倾向率仅裕民以74.9、60.5h/10a的速率显著增多。四季中仅冬季4站日照时数线性倾向率均为负值,其中塔城、额敏、托里以-5.5、-6.7、-4.9h/10a的速率显著减少;其他三季仅裕民以9.7、7.7、7.0h/10a的速率显著增多。[结论]该研究为农牧业产业结构的调整与优化、太阳能资源的合理开发与利用提供科学依据。 相似文献
5.
6.
近年来,药用植物遗传转化技术取得了很大进展,并成功培育出多种转基因药用植物。本文从外源基因整合水平、转录水平和翻译水平三个方面,对转基因药用植物分子检测技术研究进展进行了综述。 相似文献
7.
8.
Human populations have experienced recent explosive growth, expanding by at least three orders of magnitude over the past 400 generations. This departure from equilibrium skews patterns of genetic variation and distorts basic principles of population genetics. We characterized the empirical signatures of explosive growth on the site frequency spectrum and found that the discrepancy in rare variant abundance across demographic modeling studies is mostly due to differences in sample size. Rapid recent growth increases the load of rare variants and is likely to play a role in the individual genetic burden of complex disease risk. Hence, the extreme recent human population growth needs to be taken into consideration in studying the genetics of complex diseases and traits. 相似文献
9.
Magnetic measurements of ombrotrophic peat allow a reconstruction of changes in the past fallout of magnetic particles through the atmosphere. In recent peat profiles from three sites in Britain and Northern Ireland, a marked increase in saturated isothermal remanent magnetization of the peat is recorded in levels which can be shown to postdate the onset of the Industrial Revolution. Furthermore the spatial variation in contemporary isothermal remanent magnetization values is consistent with a recent industrial and urban origin for the bulk of the magnetic minerals present. Pre-Industrial Revolution values are between two and three orders of magnitude lower, suggesting that the natural cosmic and terrestrial sources previously cited for such material have been dominated in recent times by the products of human activity. Magnetic measurements provide a simple, rapid, and nondestructive method of monitoring and differentiating various types of particulate atmospheric fallout for both recent and preindustrial times. 相似文献
10.
Radiocarbon ages of submerged trees on landslide deposits in Lake Washington, Seattle, indicate that the most recent slides in three separate areas may have occurred simultaneously about 1000 years ago. Tree ring crossdating shows that seven bark-bearing trees from one of these recent slides and a tree 23 kilometers to the northwest in a probable tsunami deposit on the shore of Puget Sound died in the same season of the same year. The close coincidence among the most recent lake landslides, a probable tsunami, abrupt subsidence, and other possible seismic events gives evidence for a strong prehistoric earthquake in the Seattle region. 相似文献
11.
Jonathan Nimal Selvaraj ZHOU Lu WANG Yan ZHAO Yue-ju XING Fu-guo DAI Xiao-feng LIU Yang 《农业科学学报》2015,14(11):2265-2281
Mycotoxin contamination in agro-food systems has been a serious concern globally during the last few decades. Mycotoxins are toxic secondary metabolites produced by fungi when they grow in agro-food products and feedstuff. Several detection techniques have been developed in recent years to detect mycotoxins in the food and feed effectively. HPLC based techniques are very common in usage in the laboratories for the testing of mycotoxins. In recent years,immuno-based assays is widely used and have been reported at large due to its sensitivity and limited detection time. Immuno assay-based kits were developed effectively to be used in the fields and in storage systems to detect the mycotoxin levels. Microarray-based immunoassays developed in the recent years could simultaneously detect aflatoxin,ochratoxin,and zearalenone with the higher sensitivity. Aptamer-based assays could target the detection of ochratoxin and aflatoxins and fumonisins at high specificity in food products. In recent years,several assays reported for the simultaneous multiple detection of different mycotoxin was based on HPLC and LC-MS/MS. There is a need for the use of these advanced technologies in the commercial scale. 相似文献
12.
Mishchenko MI Geogdzhayev IV Rossow WB Cairns B Carlson BE Lacis AA Liu L Travis LD 《Science (New York, N.Y.)》2007,315(5818):1543
Analysis of the long-term Global Aerosol Climatology Project data set reveals a likely decrease of the global optical thickness of tropospheric aerosols by as much as 0.03 during the period from 1991 to 2005. This recent trend mirrors the concurrent global increase in solar radiation fluxes at Earth's surface and may have contributed to recent changes in surface climate. 相似文献
13.
哺乳动物卵巢中的细胞凋亡及其调节 总被引：3，自引：0，他引：3
细胞凋亡是近几年细胞生物学研究的热点。卵巢中发生的生殖细胞减少、卵泡闭琐和黄体退化都与细胞凋亡密切相关。就上述三个过程中的细胞凋亡进行了概述 ,并简要介绍了新近发现的几种因素对卵巢细胞凋亡的调节。 相似文献
14.
半知菌分类研究的新进展 总被引：3，自引：0，他引：3
张天宇 《西北农林科技大学学报(自然科学版)》1986,(2):96-108
本文概述了自十七世纪中叶特别是近三十多年来半知茵分类研究的进展情况。着重对主要的分生孢子形成方式和近年来提出的几个半知茵分类系统作了简略评述。 相似文献
15.
应用1953～2009年历史资料,对玉门年最多风向变化进行分析,并对近57年玉门4次年最多风向异常的气象灾害进行了分析。结果表明,57年中,玉门年最多风向有51年为东风,有4年为西风,有2年为西风和东风出现频率一样多;年最多风向异常的4年是1961、1979、1987、1998年。年最多风向异常时,气象灾害严重。1961年甘肃省粮食总产量为近60年来历史最少,1961年前后严重的旱灾使甘肃近半数农业人口严重缺粮,人口死亡剧增,到1961年末甘肃人口比1958年减少近百万。1979年是近57年中玉门年降水量最多的一年。1987年6月11日的日降水量是近57年中玉门6月份日降水量最多的一年。1998年是近57年中玉门年平均气温最高的一年。 相似文献
16.
竹提取物的化学成分及其利用研究进展 总被引：4，自引：1，他引：4
近年来,竹类资源的研究和利用在国内外十分活跃.本文综述了竹提取物中的主要化学成分,包括竹叶黄酮、多糖、氨基酸、挥发性成分等的种类和含量研究进展,总结了竹提取物的抗氧化活性等生理功能,重点论述了竹提取物的防腐抗菌作用、控制害虫作用等生物活性.提出了今后竹子化学研究的重点领域. 相似文献
17.
Steep negative concentration gradients of dissolved zinc are present between the overlying waters and the anoxic pore waters of two acid lakes. In the anoxic pore waters, the low zinc concentrations can be explained as due to the formation of relatively insoluble zinc sulfide minerals. Downward diffusive fluxes of dissolved zinc account for at least 50 to 75 percent of the recent zinc deposition to the sediments of these lakes. This downward diffusion occurs to a depth of 2 to 3 centimeters below the sediment water interface, where pronounced maxima in total zinc are observed. These subsurface peaks in total zinc have been interpreted as an indication of recent lake acidification. The present observations indicate that such subsurface peaks may also result from a diagenetic activity unrelated to recent changes in lake acidity. 相似文献
18.
19.
20.
[目的]分析1961～2010年山东诸城市气候变化特征。[方法]选用诸城市1961～2010年的气温与降水资料,采用线性倾向估计方法分析其年、季变化特征。[结果]诸城市近50年平均气温以0.383℃/10a的速度上升,各季平均气温均呈上升趋势,增温幅度为冬季>秋季>春季>夏季;近50年平均降水量以18.7 mm/10a的速度下降,春季、冬季略呈上升趋势,夏季、秋季呈下降趋势,且夏季下降最为明显,以20.9 mm/10a递减。近50年气温异常低温仅出现1年,异常高温出现了7年,均出现在20世纪90年代以后;近50年未出现降水异常偏少年份,降水异常偏多年份为6年,年总降水量呈下降趋势,说明降水量时空分布极为不均。[结论]该研究为提高气温和降水预报准确率提供依据。 相似文献