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41.
The death which occurred in juvenile population was a severe problem in the course ofPinctada maxima artificial culture. With the methods of field investigation, histological study andstatistic analyses, the epidemiological study was carried out on the disease and death in juvenile popula-tions of Pinctada maxima in the Xinying Pearl Oyster Mariculture Farm of Lingao County (for the A,B and C batches of cultured juveniles hanged in the sea) and the Xincun Pearl Oyster Mariculture Farmof Lingshui County (for the D batch of cultured juvenile hanged in the pond), Hainan Province fromNovember 1993 to April 1995. The results show that the deaths which occurred in juvenile populations of Pinctada maxima pre-sented an outbreak pattern. The peak of mortality rates, in general, occurred in 4-to 6-month old pearloyster juveniles, and the mortality rates gradully declined with the extention of pearl oyster age after cul-turing 8 months. The correlation between the mortality rates of juvenile populations and mean bodylengths of juvenile populations show that the mortality rate become higher under 4 cm of mean bodylengths of juvenile population and become obvious declined over 5 cm of mean body lengths. The peak ofmortality rate occurred in 1 ~3 cm of mean body lengths. The results of histological observation showedthat rickettsia-like organism inclusions were common, histological widespread infective agent among ev-ery batches (A, B, C and D) of cultured juvenile populations. The mean severity indices (SI) of rick-ettsia-like organism (RLO) infection were positively correlated with mortality rates of juvenile popula-tions. After or within every peaks of RLO infection were all accompanied with the peaks of mortalityrates of host populations and the mortality rates declined with decreased RLO infection. So the evidencesof histological observation and epidemiology in this study indicated that rickettsia-like organism (RLO)may be as an important pathogenic organism of disease and death of cultured Pinctada maxima. In addi-tion, a few ciliates were discovered only in part of batch A of cultured juvenile population. The mortalityrates in juvenile populations were not correlated with the weekly mean temperature and salinity of seawater. 相似文献
42.
方斑东风螺养殖技术研究 总被引:2,自引:0,他引:2
本工作对方斑东风螺亲螺培育及产卵、种苗培养、幼螺养成过程中的一系列技术进行了研究,并对其行为及生态习性进行了观察.实验结果表明,在方斑东风螺养殖过程中,不同饵料培养效果的优劣顺序为牡蛎 〉鱼 〉鲆饵 〉鳗饵.在培养密度较高时,玻璃缸流水培养效果要优于静水培养.但同为低密度培养时,静水与流水效果差异不大.水泥池养殖结果显示平面养殖每平方米可养壳高15mm以下幼螺1 000~2 000个,壳高15~20mm的1 000~1 200个,壳高20~30mm以上的600~800个.使用鲍笼立体养殖亦可获得很高的成活率与生长率,将壳高20mm以上的幼螺放入鲍笼,4~5层笼叠加立体养殖,每平方米可养1 667~2 333个,笼养60d的成活率达95%以上. 相似文献
43.
44.
菲律宾蛤仔稚贝摄食、呼吸和排泄率的研究 总被引:5,自引:0,他引:5
本文利用实验生态学的方法研究了不同温度对菲律宾蛤仔稚贝的呼吸、排泄的影响以及在25℃下菲律宾蛤仔稚贝对4种单细胞藻类的滤食率.实验结果表明,温度对菲律宾蛤仔稚贝耗氧率、排氨率有显著影响,菲律宾蛤仔稚贝在12-32℃范围内,排氨率随温度的升高呈峰值变化,在26℃排氨率达到最大值然后开始下降,耗氧率随温度的升高而增大,耗氧率(OR)和温度(t)的回归方程为:OR=0.0155e^0.696t,R^2=0.9291.O:N也随着温度的升高而升高,菲律宾蛤仔稚贝呼吸Q10平均3.8,排泄Q10平均是1.88.菲律宾蛤仔稚贝在单位时问内(g/h)对4种藻类的滤食率高低依次为扁藻〉小球藻〉金藻〉角毛藻,差异极显著(P〈0.01)。 相似文献
45.
依据煤田勘探及煤矿井下生产资料分析,认为北票煤田三宝含煤地层具有煤层和分散有机质(干络根)两种生气母质。煤层裂隙、断层附近以及煤层顶板砂岩是煤层气(瓦斯)储存的有利空间。煤系上部巨厚的泥岩层是天然的盖层。该区为超级瓦斯矿井就是佐证。初步估算煤层气资源应该在30~40亿m3,故该区煤层气具有开发利用的潜力。 相似文献
46.
论扬子地区上奥陶统五峰组观音桥段的深海成因 总被引:9,自引:0,他引:9
通过对沉积速率与现代深海沉积速率的比较及古生态学、生物古地理学、海平面变化以及沉积特征综合的分析 ,认为观音桥段形成于深海环境中 ,且属深海等深流沉积。奥陶 -志留系之交广泛发生的高频火山事件可能是生物灭绝的主要和直接原因 ,而火山事件、铱和碳同位素异常事件与志留纪初期缺氧事件在奥陶 -志留系之交的耦合作用可能是 H irnantia- Dalmanitina动物群的灭绝的主要原因。 相似文献
47.
笔者在西藏班公错-怒江结合带中段南缘嘎色地区的一套缺少化石依据的地层中,发现有孔虫Mesorbitolinasp.等化石,地层时代确定为晚侏罗世—早白垩世,层位应归属沙木罗组上部。该套地层地质时代的确定,对研究沙木罗组的沉积相,重塑古地理环境有十分重要意义。 相似文献
48.
We present a mechanical method to horizontally section soft bottom sediment cores to minimize the vertical post-sampling redistribution
of motile infaunal macroinvertebrates. A clear acrylic core tube for a standard Kajak-Brinkhurst corer was modified by cutting
a series of horizontal slits into the side of the core tube to allow the insertion of sectioning plates for physically sealing
each section immediately after core retrieval. The modification is simple, inexpensive and easily adapted to any open barrel
gravity corer. 相似文献
49.
APPLICATION OF CLAYS TO REMOVAL OF RED TIDE ORGANISMS Ⅲ.THE COAGULATION OF KAOLIN ON RED TIDE ORGANISMS 总被引:18,自引:2,他引:18
This article reports studies on the coagulation of kaolin(from Wuxian,Jiangsu,China)on various red tide organisms,and the observation for the first time that the coagulation of kaolin is much greaterthan that of montmorillonite so that kaolin is a more effective clay for removing red tide organisms.The authors’theoretical explanation and analysis by a mathematical-physical model prove that comparedto montmorillonite,kaolin has greater attraction for organism cells and therefore greater coagulation capabil-ity.This project’s studies on the effects of pH and acid-treatment show that the acid-treatment does not have much influence on the kaolin system;whereas the effect of pH on the kaolin system is the same asthat on the montmonrillonite system. 相似文献
50.