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By replacing leaf area index (LAI) with effective leaf area index (ELAI) through introduction of leaf rolling index (LRI), the distributions of photosynthetically active radiation (PAR) in the canopies of three hybrid rice combinations, Liangyou E32 with high LRI, Liangyoupeijiu with moderate LRI and Shanyou 63 with non-rolling leaves (normal), were simulated. The model based on ELAI could predict more accurately than that based on LAI. The PAR interception, conversion and utilization efficiency in the three combinations were studied to evaluate their optimal LRI and LAI. The PAR utilization efficiency of Liangyou E32 was lower due to excessive rolling leaves and less ELAI, and that of Shanyou 63 was also lower because of the faulty PAR interception and lower photosynthetic rate and saturation point at lower layer in canopy. Compared with the above two combinations, Liangyoupeijiu showed more appropriate distribution of PAR interception and conversion efficiency in canopy, and higher PAR utilization efficiency. The optimal LRI and LAI for Liangyoupeijiu were 0.11 and 7.6, respectively, which were close to the observed value, 0.11 and 7.9, respectively. However, the optimum LAI was 9.8 for Liangyou E32 and 6.2 for Shanyou 63, larger or smaller than those under the current plant density, which led to lower efficiency of PAR utilization. Besides, the optimum LRI for Liangyou E32 and Shanyou 63 were 0.12 and 0.08, respectively, which were close to the actual LRI for Liangyoupeijiu (0.11). 相似文献
996.
Kunihiko Hamagami Bui Quoc Lap Ken Mori Yasumaru Hirai 《Paddy and Water Environment》2009,7(3):187-195
The attenuation of heat flux at the water surface with aquatic plants was examined by hydraulic experiments to consider the
influence of aquatic plants on the magnitude of thermal disturbance in the closed water body. First of all, the experiment
measuring temperatures on surface of leaf revealed the thermal conductivity of the leaf which is peculiar physicality of each
aquatic plant. Then, the hydraulic experiment examined attenuation of the underwater illuminance and the heat flux in the
covered part which depending on the kind and the luxuriant density of the aquatic plants. As the result, it is clarified that
the attenuation rate of the illuminance is large in the plant with a thick leaf, and that the heat flux at the water surface
and the developmental velocity of the mixed layer decreased when the luxuriant density of the aquatic plants increased. 相似文献
997.
G. Lemaire S. C. Da Silva M. Agnusdei M. Wade J. Hodgson 《Grass and Forage Science》2009,64(4):341-353
In continuously stocked swards or pastures the frequency at which individual tillers and individual leaves are defoliated by ruminant livestock, relative to leaf lifespan of the grass species within the sward, determines the proportion of each leaf defoliated before senescence, and hence the efficiency of harvesting of herbage. In this paper, sets of data obtained in a range of climatic conditions and with a range of grass species are used in order to document this relationship. It is shown that the frequency of defoliation of individual tillers or individual leaves is closely linked to the average stocking density used within a period of time for maintaining a steady state sward or pasture height, herbage mass or leaf area index. Consequently, any decrease in herbage growth rate should lead to a decrease in the efficiency of harvesting of herbage and then to a more than proportional decrease in total herbage consumption by ruminant livestock. These effects will be more important for grass species having short leaf lifespan than for species with long lifespan. In rotational stocking, the link between herbage growth rate and frequency of defoliation of leaves can be broken by controlling the grazing interval, so any decrease in herbage growth would not be systematically associated with a decrease in efficiency of harvesting of herbage. Rotational stocking should be more efficient than continuous stocking in low herbage production conditions, while in high herbage production systems rotational and continuous stocking would have similar efficiency. The implications of these conclusions for the management of swards and pastures to meet different objectives are discussed briefly. 相似文献
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在良好栽培条件下,玉米品种的产量水平在公顷4.5万株稀植时,主要是由配合力决定的,而在公顷6.0万株密植时耐密性又成为主要影响因素.耐密性是一个综合性状.耐密性强(或耐密型)玉米,是以较高配合力为前提的,不仅株型紧凑、而且还具有秆强、根系发达、结实性好、易抓苗、植株整齐度高等特点.耐密型玉米适于密植的根本原因是耐密性强.公顷11000~12000kg 高产群体,由于品种的繁茂程度、光合效率以及经济系数有差异,其主要数量指标为总光合势316.4~439.2万m2·日/ha,最大叶面积系数4.25~5.53,净同化率5.76~7.55g/m2·日,经济系数0.496~0.549.籽粒灌浆初期穗位处由间透光率22.8%~25.6%,近地面处8%~10%. 相似文献
1000.
播期和密度对镇麦168农艺和品质性状的影响 总被引:2,自引:0,他引:2
为探寻小麦新品种镇麦168高产优质栽培的适宜播期与密度,通过二因素随机区组试验,分析了播期和密度对该品种农艺和品质性状的影响。结果表明,播期和密度对镇麦168的产量、部分农艺和品质性状均有影响。随着播期的推迟,产量、面团形成时间和稳定时间、湿面筋含量均呈现先升后降趋势;适当控制密度可协调有效穗数、穗粒数、千粒重,进而提高产量,同时可增加面团稳定时间、籽粒蛋白质和湿面筋含量。在本试验条件下,该品种优质高产适宜播期和种植密度分别为10月31日和270万株·hm-2。 相似文献