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71.
为解决农业试验统计分析软件、扬州分析器(2.2)、Excel进行回归分析建立的部分非典型性肥料效应方程推荐的施肥量出现异常偏大、偏低甚至负值,脱离当地生产实际的问题。该文应用概率理论的基本知识和频数的原理和方法,对油菜田间肥效试验数据应用频率分析法进行统计分析,得到的油菜优化施肥量产量为1732.4 kg/hm2,氮、磷、钾优化组合合范围分别为210.36~149.64、81.89~58.11、81.89~58.11 kg/hm2,与试验地(田)和当地生产实际相吻合。该研究是在频率分析的基础上,用加权平均方法,确定各种不同产量目标的生产因素组合,将其中产量高,出现频率大(稳产),用肥节省的组合作为优化生产措施,具有增加施肥决策信息量,减少或避免小概率事件的风险的优点。可解决肥效试验数据分析统计汇总应用扬州分析器(2.2)、Excel、DPS等统计分析软件进行回归分析建立的部分非典型肥料效应函数推荐的施肥量和目标产量出现异常值,与当地生产实际不相符的问题。肥料效应函数方程经方差分析不显著的试验,能否应用该研究方法进行施肥决策,推荐氮、磷、钾肥料优化组合和优化施肥量产量,还需在以后的工作实践中进一步探讨。 相似文献
72.
73.
只有搞清油锯的振动特性,找出油锯振动的根源并掌握其振动规律,才能有的放矢地制订出减振方案并为新型低振动油锯的研制打下良好的理论基础。一、研究对象和测试仪器研究对象和测试样机,选取西北林机厂生产的GJ-85型油锯,柳州机械厂的051型油锯和苏联的урал-2型油锯。样机皆经磨合和试运转。测试仪器选用YD-8型和YD-1型压电式加速度传感器。前者频率范围2-18KHZ, 相似文献
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75.
应用佳多频振式杀虫灯对松毛虫Dendrolimus spp.进行预测预报和防治试验,结果证明对松毛虫成虫有诱集作用,完全可以用于对松毛虫的监测.在利用佳多频振式杀虫灯进行马尾松毛虫Dendrolimus punctatus Walker防治试验中,取得了平均85%以上的防治效果,成本远低于其他防治措施的成本. 相似文献
76.
轴流泵水力模型压力脉动和振动特性试验 总被引:4,自引:0,他引:4
采用高频压力传感器对某一轴流泵模型叶轮进口、叶轮出口和导叶出口3个压力测量点,分别在3个转速1 450、1 200、1 000 r/min的额定流量工况条件下,进行了系列压力脉动测量试验。试验研究结果表明,不同转速下的压力脉动峰峰值不符合泵相似定律准则;不同转速条件下,叶轮进口处的压力脉动主频均为叶频,但叶轮出口的压力脉动主频随着转速的变化而发生漂移;泵内最大压力脉动峰峰值在泵内的位置也随之改变。通过分析转速变化对不同压力测点处的主频和泵不同位置的振动特性影响,发现试验泵不同位置处的振动以流体诱导的低频信号和转子系统质量不均匀诱导的轴频及其倍频为主要特征信号。从振动与压力脉动的频域来看,在0~2倍轴频范围内变化趋势基本相同,且速度变化对二者有相似的影响。在不同转速条件下,压力脉动的频率以1~4倍轴频为主要频域信号范围,但在不同位置处,振动频域范围仍主要以1倍和2倍的轴频信号为主。 相似文献
77.
针对木工机床的加工特点,提出将系统加工过程中最易发生共振的一阶固有频率作为机床结构动态优化设计的目标,并分别分析了质量、刚度和阻尼对该阶固有频率的变化率.以此为基础,对Author503型木工数控加工中心的主轴箱支撑架进行了动态优化设计.结果表明,采用这种方法不但可以使系统该阶固有频率得到显著提高,且可明显减小振型,优化效果显著. 相似文献
78.
Lars Hedenäs Irene BisangAnders Tehler Marianne HamnedeKlas Jaederfelt Göran Odelvik 《Biological conservation》2002,105(3):321-331
A new, resource-efficient, herbarium-based method for estimating temporal frequency changes in species, especially of non-vascular plants and fungi, is presented. It is based on a reference data set for the temporal distribution of general collecting activity for the organism group and geographical area of interest. The reference data set includes the collecting year of 650-1000 randomly selected herbarium specimens. The technique relies on the assumption that the temporal distribution of herbarium collections reflects the collecting activity in a region. The temporal distribution of collections of example species is compared with that of the reference data set to correct for the collecting intensity. Thus, cases that are explained by changes in general collecting frequency can be separated from those where other causes are likely. Species of the latter category need to be examined individually in order to assess whether the actual causes for the detected frequency variations are due to environmental changes or other factors. The present method provides a tool to assess actual increases and decreases of moderately frequent to common taxa, to aid in tracing predicted or unpredicted changes in nature. 相似文献
79.
In South Germany, soil erosion is as old as farming and dates back to Early Neolithic times. Its sedimentary products form thick colluvial and alluvial sediment bodies in all drainage basins. Numerous local studies exist but the extrapolation of findings from local case studies to a regional scale has been problematic. Here, a graphical approach is used for frequency analysis of existing data. A frequency distribution for optical dates on colluvial sediments from the beginning of agriculture until 1200 AD was constructed by: (1) representing the optical ages by Gaussian-distributions and (2) summing all the single curves. The resulting graph clearly shows phases of increased colluviation during periods of stronger human impact. A first significant increase occurred during the Bronze Age. During the Iron Age/Roman period and at around 800 AD, distinct maxima appear in the distribution, and highest frequencies are present towards the end of the analysed period at around 1100 AD. Conclusions that can be drawn from such an approach are limited by sampling bias and other factors, but for the analysed period, and on a regional and long-term scale, colluviation seems to have been mainly triggered by intensity of land use. Climatic fluctuations are of only secondary importance. Rainfall events that were sufficiently erosive to produce colluvial sediments occurred throughout the agricultural periods. The limiting factor for colluvium production was sensitivity of the landscape to erosion, and this is a result of land use. 相似文献
80.
Flood mitigation in irrigation tanks and paddy fields is their favorable aspect though its practical effect is not known very
well. A dynamic and systematic approach is presented to assess flood mitigation in a tank irrigated paddy fields area in the
worst case where no static buffer function is expected. Based on the linear control theory, transfer function models for runoff
process in catchments are identified. Hydraulic models are developed to represent flood dynamics in irrigation tanks, paddy
fields, and drainage channels. These models are integrated as an ordinary differential equations system. Then, using the perturbed
linear system, flood mitigation in each component of the system is examined in terms of frequency response. An application
example demonstrates that a tank irrigated paddy fields area has a significant flood mitigation effect as a low-pass filter.
This method has the advantage of assessing flood mitigation even in the case of an increase in the total runoff ratio. 相似文献