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1.
Early life history connectivity of Antarctic silverfish (Pleuragramma antarctica) in the Ross Sea 下载免费PDF全文
Cassandra M. Brooks Jilda Alicia Caccavo Julian Ashford Robert Dunbar Kimberly Goetz Mario La Mesa Lorenzo Zane 《Fisheries Oceanography》2018,27(3):274-287
A recent population hypothesis for Antarctic silverfish (Pleuragramma antarctica), a critical forage species, argued that interactions between life history and circulation associated with glacial trough systems drive circumpolar distributions over the continental shelf. In the Ross Sea, aggregations of eggs and larvae occur under fast ice in Terra Nova Bay, and the hypothesis predicted that dispersing larvae encounter outflow along the western side of Drygalski Trough. The outflow advects larvae towards the shelf‐break, and mixing with trough inflow facilitates return toward the inner shelf. To examine the hypothesis, we compared samples of P. antarctica collected near Coulman Island in the outflow, along Crary Bank in the inflow, and a third set taken over the rest of the Ross Sea. We ruled out misidentification using an innovative genetic validation. Silverfish larvae comprised 99.5% of the catch, and the highest population densities were found in Drygalski Trough. The results provided no evidence to reject the population hypothesis. Abundance indices, back‐calculated hatching dates, length distributions and growth were congruent with a unified early life history in the western Ross Sea, constrained by cryopelagic early stages in Terra Nova Bay. By contrast, a sample in the Bay of Whales revealed much smaller larvae, suggesting either a geographically separate population in the eastern Ross Sea, or westward connectivity with larvae spawned nearby by fish sourced from troughs upstream in the Amundsen Sea. These results illustrate how hypotheses that integrate population structure with life history can provide precise spatial predictions for subsequent testing. 相似文献
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Wheat germ flour (WGF) has been developed as a functional food ingredient with high nutritional value. In this study, WGF was applied in steamed bread-making in order to improve the quality of Chinese steamed bread (CSB). Partial substitution of wheat flour with WGF at levels of 3%, 6%, 9% and 12% (w/w) was carried out to investigate physicochemical properties of blends and their steaming performance. Falling number (FN) values of composite flours ranged from 199 to 223 s. Viscosity analysis results showed that wheat flour mixed with WGF had higher pasting temperature and lower viscosities. Dough rheological properties were also investigated using farinograph and extensograph. The addition of WGF diluted the gluten protein in dough and formed weak and inextensible dough, which can be studied by scanning electron microscope (SEM) analysis. CSB made with WGF had significantly lower volume, specific volume and higher spread ratio. The sensory acceptability and physicochemical quality of CSB were improved with the application of a low level of WGF (3% and 6%). However, results showed that a high level of WGF over 9% is not recommended because of unsatisfactory taste. As a whole, addition of appropriate level of WGF in wheat flour could improve the quality of CSB. 相似文献
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利用常规资料和多普勒资料,对2008年9月7日的一次较长生命史飑线过程进行综合分析,对多普勒雷达几个产品的适用性进行初步探讨。结果表明,在雷暴单体发展各个阶段,从雷达观测数据上可以分析出系统流场以及环境风场,两者相互影响会在雷达回波上显示特殊的配置形势。这种在大面积正速(负速)区里嵌套一小块数值均匀的负速(正速)区的配置经常被误判为中气旋,实际上这是由于在对流系统中层发生的径向辐合而产生的。在适当仰角的速度图(V26)上迭加风暴追踪信息(58STI),便于分析出风暴的发展阶段。通过对风暴追踪信息产品在单体发展的各个阶段上的预报准确性探讨,以及一些其他产品的适用性研究,并将结论利用于短时预报和诊断分析上,以期提高目前短时预报的水平。 相似文献
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利用探空观测资料以及FY-2D气象卫星云图、多普勒天气雷达回波等非常规气象观测资料,采取天气学诊断分析方法,对2009年7月26日出现在广东清远市一次局地突发性暴雨过程进行了诊断分析。结果表明,副热带高压边缘的不稳定气流及南支槽前的上升运动是此次局地暴雨过程的天气尺度系统和大尺度环流背景;暴雨发生前大气不稳定能量不断积累,为中尺度系统形成创造了有利的环境条件;地形与降水有着密切的关系,中小尺度地形使近地面上升气流增强,造成了对流云团在该地不断生成和发展。 相似文献
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研究了以Dirac测度为源的拟线性退化抛物方程ut-Δum=δ(x),(x,t)∈Q的Cauchy问题解的唯一性,其中δ(x)是Dirac测度,m〉1,Q=RN×(0,+∞). 相似文献
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本文对一类半线性变系数抛物型方程初边值问题建立了一个二阶差分格式,证明了差分格式解的存在唯一性、关于初值的无条件稳定性和在L∞范数下阶数为O(2τ+h2)的收敛性,最后给出的数值算例验证了理论结果。 相似文献
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聚光回热式太阳能土壤灭虫除菌装置光热性能 总被引:1,自引:1,他引:0
该文针对传统设施农业土壤灭虫除菌过程使用化学消毒法所带来的环境污染和农作物药物残留等问题,提出了新型聚光回热式太阳能土壤灭虫除菌装置,利用太阳能聚光集热技术加热空气进而对农业种植土壤进行高温消毒,同时将土壤所含有机物加热挥发,实现对农业种植土壤的修复,同时处理后的热土壤对进料空气进行预热,提高了装置的热能利用效率。该文介绍了聚光回热式太阳能土壤灭虫除菌装置的工作原理,利用光学仿真软件对装置中复合多曲面聚光器的光学效率进行了计算,基于光学计算结果,对聚光回热式太阳能土壤灭虫除菌装置的光热性能进行了室外试验,测试了装置的空气加热温度和集热效率。结果表明,用于土壤灭虫除菌的热空气在聚光比为3.6,流动速度为1.075 m/s时,装置的集热效率最高,加热后空气温度最高达到了88℃左右,集热效率为65%左右,能够满足农业土壤灭虫除菌所需的温度需求。 相似文献