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91.
滴灌施肥对‘特罗维它’甜橙生长结果的影响   总被引:5,自引:0,他引:5  
 以卡里佐枳橙砧‘特罗维它’甜橙为材料,以每年撒施10次肥料为对照,研究了年施肥总量一定,不同滴灌施肥频率(每年4次、10次和16次)对树体生长、产量和品质的影响。2002—2007年的结果显示,仅个别年份的处理与对照的树干粗度、树高和冠径存在显著差异以外,到试验结束时,不同滴灌施肥频率对树干粗度、树高和冠径大小无显著影响,滴灌施肥与对照间的树体生长无显著差异。滴灌施肥可显著提高果实产量,处理的累计产量比对照高29.4% ~ 36.5%;增加滴灌施肥频率无显著增产作用;滴灌施肥对果实品质无显著影响。建议碱性紫色土柑橘园滴灌施肥频率为每年4次。  相似文献   
92.
A field experiment was carried out in Central Italy to assess the reliability of petiole sap for determining nitrogen (N) status on processing tomato. The crop was fertilized with different N rates and fertigation-irrigation frequencies. Reduced-N and nitrate-N concentrations were determined by lab analyses at 30, 42, 57, 71, and 84 days after transplanting. At each sampling date, the assessment of N nutritional status as resulted by sap test was compared with the actual plant N status as determined by nitrogen nutrition index (NNI). Results from sap test were in agreement with NNI indications for about 2/3 of crop cycle that represents the crucial time for N fertilizer management in tomato. The correlation coefficient of the two methods was, on average 0.854 and it was statistical significant in the whole sampling period. The nitrate concentration in the petiole sap provided a good agreement with laboratory analysis across the full range on N-nitrate (NO3) concentrations examined.  相似文献   
93.
不同滴灌施肥模式对棉花产量及养分吸收的影响   总被引:5,自引:1,他引:4  
通过等养分和等成本施肥田间试验,研究不同滴灌施肥模式对棉花产量及养分吸收的影响。试验设4种滴灌施肥模式,分别为常规基施(CK)、常规追施(DCK)、普通滴灌专用肥(F1)和高磷钾滴灌专用肥(F2)。结果表明,在等养分施用条件下,高磷钾滴灌专用肥和普通滴灌专用肥处理的棉花干物质重、养分吸收量和产量均显著高于常规基施处理,但普通滴灌专用肥和常规追施处理差异不大;常规基施处理的氮肥和磷肥的利用率最低,普通滴灌专用肥和常规追施处理的氮肥和磷肥利用率差异不显著,高磷钾滴灌专用肥可显著提高磷肥利用率。在等成本施用条件下,常规追施处理的棉花干物质重、养分吸收量和产量最高,而高磷钾滴灌专用肥、普通滴灌专用肥和常规基施处理无显著差异。因此,滴灌专用肥尤其是高磷钾滴灌专用肥具有较好的应用效果,但是如何降低肥料成本是滴灌专用肥技术面临的重要问题。  相似文献   
94.
ABSTRACT

Impatiens (Impatiens wallerana Hook. f.) is the most important annual bedding plant in the United States, based on wholesale dollar volume. Production of high-quality plants requires optimization of the nutrition regimen during growth, especially the total nitrogen (N) concentration and the ratio of N sources. The objective was to determine the N concentration and the nitrate (NO3 ??N):ammonium (NH4 +?N) ratio of N source that optimized bedding-plant impatiens growth and flower development. Four N concentrations (3.5, 7, 10.5, and 14 mmol N · L?1) were used in factorial combination with four ratios of NO3 ??N:NH4 +?N (4:0, 3:1, 1:1, and 1:3). Application of treatments was made for 30 d. Then for 10 d only deionized water was applied to reduce salt buildup. Substrate pH was lowest (4.9) with the NH4 +?N source and electrical conductivity (EC) highest, but never > 2.4 dS m?1. Nitrogen concentration and N source displayed an interaction for most growth parameters. Shoot fresh and dry weights and flower bud number were maximized at the 1:3 NO3 ??N:NH4 +?N ratio with a N concentration of 10.5 mmol L?1. However, plant diameter, leaf number, and leaf chlorophyll content responded quadratically to N form ratio, with the 1:1 ratio optimum at a concentration of 10.5 mmol N· L?1.  相似文献   
95.
Over the 3-year period of study (2005–2007) the effects of fertigation on vegetative potential, fruit properties, and production of apple cultivars Idared and Wilmuta were investigated. Fertigation measures, mainly applied over the second part of growing season, when vegetative growth is brought to a close, had positive effect on these parameters. Cultivar Idared was more productive. Its fruits were larger and more ripe when fertigated in comparison with the control cultivar. Cultivar Wilmuta responded similarly to fertigation.  相似文献   
96.
Abstract

Squash, cv Dixie, grown on a Lakeland sand was subjected to factorial combinations of 3 tillage systems and 2 N application methods during 1979 and 1980. Fruit yield was greatest with a combination of moldboard plow tillage and application of 22 kg N/ha preplant and 18 kg/ha increments of N by fertigation 2, 3, 4, 5 and 6 weeks after planting. Plant growth and nutrient uptake were greatest and N available for potential contamination of the ground‐water was least with subsoil‐bed tillage and N application by fertigation. Disc harrow tillage with 67 kg N/ha preplant and 45 kg N/ha 4 weeks after planting resulted in 42% less yield, 61% less plant growth, 29 to 64% less nutrient uptake and more than 5 times as much N available for potential contamination of the groundwater as the best practices.  相似文献   
97.
The aim of this study was to improve the fertilizer‐nitrogen‐use efficiency (NUE) for a sustainable citrus production where yield, fruit quality, and environment are reconciled. A soil pot experiment was conducted using 5‐year‐old orange trees (Citrus sinensis cv. Navel Lane Late) to determine the response of NUE to timing of N‐fertilizer supply. An equal N rate (50 g tree–1) following two seasonal supply distributions was tested: (1) ENS (early supply from March to June of 75% of the N rate, with the remaining 25% administered between July and October) and (2) LNS (late supply of the bulk of the N rate with 25% between March and June and 75% between July and October). Labeled fertilizer (5 atom% 15N excess) was applied in order to accurately quantify N uptake, its partitioning among plant–soil compartments and NUE at the end of fruit drop and at fruit maturity. LNS resulted in a significant increase in NUE in both stages (up to 19% at the end of fruit drop and 9% at fruit maturity), while also increasing summer/autumn flush development. ENS showed lower fruit abscission, an enhanced final fruit load (up to 45%), and a more profuse development of spring flush. It is worth mentioning that LNS led to higher 15N content in the majority of the tree storage organs available for next spring growth resumption. The amount of 15N remaining in the soil of ENS trees at the end of the trial, which represented 16% of the supplied 15N, was 1.5‐fold higher than that of LNS trees as a result of the lower NUE of the former. Irrespective of the seasonal distribution of the fertilizer, mean 15N recovery in the soil–plant system at the end of the trial was about 71%. The results clearly confirm that the N seasonal distribution curve affects NUE in young citrus trees and NUE increases when the bulk of supply of the N rate is delayed to the summer months.  相似文献   
98.
通过室内模拟滴灌施肥,研究不同氮肥及磷肥混合施用对土壤氮素水平分布的影响。结果表明:土壤含水量在水平方向上呈线性减缓分布,不同种类氮肥单施与配施对土壤含水量影响不大;氮磷肥配施较氮肥单施可加速土壤硝态氮随着水分的迁移速度;土壤铵态氮在滴头处浓度最大,在水平方向上的最大迁移距离为7.5cm。  相似文献   
99.
通过在次生盐碱地上利用高垄覆膜滴灌全价营养液栽培黄瓜,研究不同浓度处理对黄瓜的影响。试验设置3个处理:处理A为1/4标准剂量,处理B为1/2标准剂量,处理C为标准剂量。结果表明:处理B的高垄EC值介于其它两个处理之间,植株长势最好,产量最高,对品质没有影响。因此,1/2标准剂量浓度是最适浓度。  相似文献   
100.
轮灌条件下灌溉施肥系统混肥过程变论域模糊控制   总被引:1,自引:0,他引:1  
灌溉施肥系统的混肥过程在轮灌条件下表现出非线性、时滞性、时变性和不确定性的特点。为解决该系统的控制问题,提出了一种变论域的模糊PI控制策略(VFPI),算法采用一组比例指数函数作为伸缩因子对模糊控制器的论域进行在线调整,同时引入了一个协模糊控制器,通过测量系统流量的变化在线调节控制器积分系数的基准值。为验证控制算法的有效性,搭建了灌溉施肥控制系统的试验平台,分别设计了4组不同配方内容和3组不同轮灌条件的模拟试验,采用本文提出的VFPI控制算法和常规PI控制算法进行了对比试验。试验结果表明,所提出的VFPI控制策略能够更好地适应配方内容变化以及轮灌条件变化对混肥过程造成的影响;相比于常规PI控制,VFPI控制的调节时间更短、超调量更小、动态过程更平稳。  相似文献   
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