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This paper addresses the interdecadal variation of the West African summer monsoon (WASM) along with its background of atmospheric circulation and possible physical mechanism over the past 32?years (1979–2010). It is indicated that the WASM starts to strengthen from 1998 as the rainfall begins to increase over western West Africa on the whole, which shows a new interdecadal variation. In this interdecadal variation, the strengthened ascending motion corresponding to enhanced divergence (convergence) movement on the upper (lower) troposphere is prone to develop the local circulation of the monsoon. Moreover, the strengthened southwestern (eastern) wind on the lower (upper) level leads to more moisture from the Atlantic and the Gulf of Guinea transported to the West African continent. In addition, the summer subtropical high over the north Atlantic and western West Africa is strong and northward, and the tropical east wind is also strong. Statistically, the weaker (stronger) the spring North Atlantic Oscillation (NAO) is, the stronger (weaker) the tropical easterly is, and then the WASM is also stronger. But the effect of the NAO on the decadal variation of the WASM is not so significant from the north Atlantic anomaly sensitivity simulation with a single model. This is also an indication that the relationship between the WASM and NAO is complicated in an interdecadal time scale and is needed further study. In terms of sea surface temperature (SST) variation, the tendency is toward warming in the subtropical north Pacific, the south Pacific and north Atlantic. Numerical simulation experiments and data analysis show that the SST variation in the north Pacific plays an important role in the latest interdecadal strengthening of the WASM during the past 32?years, while the influences of the south Pacific and the north Atlantic SST anomalies are not so significant to the associated atmospheric circulation changes. 相似文献
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三十烷醇乳粉在海带养殖上的应用试验 总被引:3,自引:0,他引:3
本文报道了三十烷醇乳粉在北方海带养殖中的应用。在海带苗出库时,用浓度为0.5ppm的三十烷醇乳粉将其浸泡12小时,或夹苗时用浓度假ppm,将其浸泡2小时,可使海带增产20%左右。此法低耗高效,简单易行,适宜于海带养殖中大面积推广。 相似文献
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2019年全球主要温室气体浓度继续保持上升趋势,全球平均温度比工业化前水平高1.1(±0.1)℃,为有气象记录以来第二暖年。海洋热容量及海平面高度创新高,海冰面积偏小。年内,全球各地发生了许多重大天气气候事件,包括多地遭遇暴雨洪涝侵袭,澳大利亚以及亚洲和欧洲多国受干旱影响,全球极端热带气旋频发,欧洲及澳大利亚等地遭遇异常高温热浪天气,北美和欧洲遭受寒流和暴风雪袭击,多地出现强对流天气。分析表明,印度洋偶极子(IOD)处于正位相、赤道中太平洋地区海温持续偏暖以及副热带高压系统控制是澳大利亚高温少雨的主要原因,最终引发严重的森林山火;前期异常偏强的IOD正位相叠加持续时间异常偏长的热带低压,促进了2019年印度7—8月强暴雨事件的发生发展。 相似文献
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Jinhua Pan Xin Jiang Xiaojie Li Yizhou Cong Zhuangzhi Zhang Zhiling Li Weili Zhou Houwei Han Shiju Luo Guanpin Yang 《中国海洋大学学报(英文版)》2011,10(2):147-152
Seagrass restoration as part of ocean ecosystem protection has been launched for many years all over the world, but intensive
research on this subject in China has just begun in recent years. Seed broadcasting has been widely accepted as the most potentially
useful method for seagrass restoration over large areas. We examined the influence of key environmental factors on seed germination
to help promote eelgrass bed restoration. Under anoxic conditions, the influence of temperature and salinity on the germination
rate of eelgrass (Zostera marina L.) seeds was examined at different combinations of four temperatures (4, 9, 14, and 24°C) and nine salinities (5 to 45,
increment of 5). The effect of significant interaction of temperature and salinity on germination rate was observed (ANOVA)
(P<0.001). The highest germination rate (83.3 ± 3.5)% was reached in 8 weeks at 14°C and salinity 5. Higher temperature significantly
increased the germination rate at salinity 5 (P<0.001) during the whole observation period except for 24°C, while lower salinity significantly increased the germination
rate at 14°C (P<0.001). Although significant interaction was found between temperature and salinity (P<0.001), the influence of salinity was stronger than that of temperature for the germination of eelgrass seeds. These results
provide useful information for the propagation of artificial seedlings for seagrass restoration in China. 相似文献
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宁夏自治区南部固原寺口子剖面位于青藏高原东北缘,记录了青藏高原隆升、扩展与区域气候变化之间的相互作用过程,重建该地区气候演化历史对于揭示高原隆升与全球气候变冷对亚洲大陆腹地干旱化的影响具有重要意义。通过对寺口子剖面晚渐新世—第四纪地层沉积物色度(a~*、b~*、L~*)的系统测量,建立了29~0.5 Ma颜色指标变化序列,结合研究区内已发表的磁化率、孢粉和总无机碳数据,揭示出该区域气候经历了四个阶段:29~24.8 Ma为最湿热阶段、23.8~18 Ma为较湿热阶段、18~5 Ma为逐渐变冷阶段、5~0.5 Ma为快速变冷阶段。剖面记录了25~24 Ma、18 Ma、5 Ma两次显著的气候变冷事件和3 Ma气候变暖事件。结合青藏高原东北缘新生代盆地气候代用指标,发现这些气候变冷事件和3 Ma气候变暖事件具有区域性。通过对比深海氧同位素记录、北太平洋粉尘通量记录、青藏高原构造隆升事件和研究区气候演化特征,我们认为青藏高原隆升和全球气候变化共同控制了区域气候演化,但在不同时期所起作用有所差异。 相似文献
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基于1961 - 2018年冬季逐日降水资料, 研究了新疆北部不同类型暴雪的时空分布和环流特征。结果表明, 冬季新疆北部的局地暴雪日数最多(73.1%), 区域暴雪次之(20.9%), 大范围暴雪最少(6.0%)。总暴雪、 区域暴雪和大范围暴雪日数呈显著的增加趋势, 局地暴雪的增加趋势不显著。总暴雪、 局地暴雪和区域暴雪日数在12月最多; 大范围暴雪日数在2月最多。20世纪60 - 80年代, 新疆北部冬季以局地暴雪为主, 暴雪中心主要位于伊犁河谷和塔城地区北部; 90年代至今, 区域暴雪和大范围暴雪日数显著增加, 除伊犁河谷和塔城地区北部外, 阿勒泰地区、 天山北坡中段的暴雪日数增加显著, 乌鲁木齐成为天山北坡新的暴雪中心。新疆北部冬季暴雪的环流形势可分为3类6型, 其中锋区波动类最多, 低槽类次之, 低涡类最少。20世纪90年代前, 锋区波动类最多; 进入21世纪后, 低槽类明显增多。 相似文献