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61.
Previous work has hypothesised that cows in low body condition become lame. We tested this in a prospective longitudinal study. Body condition score (BCS), causes of lameness and milk yield were collected from a 600-cow herd over 44-months. Mixed effect binomial models and a continuous outcome model were used to investigate the associations between lameness, BCS and milk yield. In total, 14,320 risk periods were obtained from 1137 cows. There were 1510 lameness treatments: the most common causes of lameness were sole ulcer (SU) (39%), sole haemorrhage (SH) (13%), digital dermatitis (DD) (10%) and white line disease (WLD) (8%). These varied by year and year quarter. Body condition was scored at 60-day intervals. BCS ranged from 1 to 5 with a mean of 2.5, scores were higher in very early lactation but varied widely throughout lactation; approximately 45% of scores were <2.5. The key finding was that BCS < 2.5 was associated with an increased risk of treatment for lameness in the following 0–2 months and >2–4 months for all causes of lameness and also specifically for SU/WLD lameness. BCS < 2.5 was associated with an increased risk of treatment for SH in the following 0–2 months but not >2–4 months. There was no such association with DD. All lameness, SU/WLD, SH and DD were significantly more likely to occur in cows that had been lame previously, but the effect of BCS was present even when all repeat cases of lameness were excluded from the analysis. Milk yield was significantly higher and fell in the month before treatment in cows lame with SU/WLD but it was not significantly higher for cows that were treated for DD compared with non-lame cows. These findings support the hypothesis that low BCS contributes to the development of horn related claw lameness but not infectious claw diseases in dairy cows. One link between low BCS and lameness is a thin digital cushion which has been proposed as a trigger for claw horn disease. Cows with BCS 2 produced more milk than cows with BCS 2.5, however, this was only approximately 100 kg difference in yield over a 305-day lactation. Given the increased risk of lameness in cows with BCS 2, the direct costs of lameness and the small variability in milk yield by BCS, preventing cows from falling to BCS < 2.5 would improve cow welfare and be economically beneficial.  相似文献   
62.
Livestock disease surveillance is particularly challenging in resource-scarce settings, where disease events are often unreported. Surveillance performance is determined as much by the quantifiable biological attributes of the disease, as it is by motivations and barriers perceived by livestock keepers for disease reporting. Mixed methods designs, which integrate the collection, analysis and interpretation of qualitative and quantitative data in a single study, are increasingly used across different disciplines. These designs allow for a deeper exploration of the topic under investigation, than can be achieved by either approach alone.  相似文献   
63.
中国北方地区双孢蘑菇栽培新技术   总被引:1,自引:0,他引:1  
针对双孢蘑菇栽培周期长、原料日趋紧张、劳动成本高、产量低等问题,开展新型菇房、配方、覆土技术、发酵技术试验示范。结果表明,新型菇房可用于周年生产;新型玉米芯配方,一次发酵时间分别比对照缩短4 d和6 d,产量达到到10.29 kg·m-2,在5%水平上差异显著,每平方米的成本由3元下降为0.4元;新型覆土配方,产量比黄土高37.33 kg,比草炭土产量高41.17 kg,在5%水平上差异显著。  相似文献   
64.
针对中国南方地区人工林树种林种单一、稳定性较差、物种多样性低,以至于生态服务功能低下,优质森林资源储备不足的问题,从改善林种结构,提高林分单位面积产量及生态效益出发,开展了南方主要珍贵阔叶树种多树种混交造林技术研究。结果表明,采用多树种混交模式,树种生长显著加快,单位面积总蓄积量增加,且在促进林木胸径生长方面效果显著,有利于大径材的培育;此外,多树种混交能够降低凋落物层C/N,养分分解转化快,生态稳定性更强。因此,珍贵树种多树种混交栽培模式具有可行性。  相似文献   
65.
[目的]为混播种植方式在提高玉米幼苗光合能力以及油污土壤生物修复中的应用提供科学依据。[方法]在人工模拟石油污染土壤条件下,采用盆栽方法探讨石油胁迫下混播对玉米幼苗叶绿素含量的影响。[结果]石油污染对玉米幼苗叶绿素的形成有抑制作用;无论在常规还是在石油污染的备件下,不同品种玉米与大豆混播值均高于相应品种玉米单播值。[结论]混播对土壤石油污染表现出一定的耐受性,在玉米增产和油污土壤植物修复方面能够起一定的指导作用。  相似文献   
66.
[目的]对湖北省某猪场发生的以体温升高、部分病猪死亡等为主要特征的疾病进行诊断。[方法]采集发病猪的脾脏、淋巴结等样品,应用PCR方法进行实验室检测。[结果]经实验室检验,结合临床症状,诊断为HP.PRRSV及PCV2混合感染。高致病性猪蓝耳病毒阳性率为40%,猪圆环病毒2型阳性率为90%。[结论]通过采取综合防控措施,病情得到有效控制,减少了猪场的经济损失。  相似文献   
67.
[目的]评价0.5%毒死蜱药肥混剂对韭菜韭蛆的防治效果。[方法]于2012~2013年,在山东省烟台市福山区进行了0.5%毒死蜱药肥混剂防治韭菜韭蛆田间药效试验。[结果]0.5%毒死蜱药肥混剂在1875g/hm2施用量下,2012和2013年药后21d的防效分别达77.15%和80.00%,21d虫口防效分别达99.55%和97.30%,增产效果分别为59.06%和30.09%,显著高于对照药剂5%毒死蜱颗粒剂。[结论]应用0.5%毒死蜱药肥混剂防治韭蛆,推荐使用剂量为l125~1875g/hm2。  相似文献   
68.
蔬菜茎叶青绿多汁,适口性好,含有丰富的粗蛋白、粗脂肪和粗纤维,是牲畜的优质饲料.然而,除了小部分作为青绿饲料直接饲喂动物外,大部分蔬菜茎叶下脚料被遗弃或抛弃,这不仅造成资源浪费,而且造成环境污染.通过青贮等方式将蔬菜茎叶加工成动物饲料,既可以提高其利用价值,又可以取得良好的社会效益.对蔬菜茎叶混合青贮技术、影响青贮效果的因素及其在养殖业中的应用进行了综述.  相似文献   
69.
除草剂混合标准溶液中标准物质稳定性研究   总被引:1,自引:0,他引:1  
选取德国DR公司生产的28种除草剂标准物质,将其配制成混合标准溶液后转移至20 mL带聚四氟乙烯衬盖的棕色螺口样品瓶中,于-18℃避光贮存,采用液相色谱串联质谱法测试各组分量值随贮存时间的变化。结果表明:在90天内,标准物质各组分量值的标准偏差在12~73μg/L范围内,最大相对标准偏差为3.04%(n=5),测量结果的相对不确定度小于5.60%。在置信度为95%时,标准物质各组分量值在(1 000±113)μg/L范围内,测量的偏差不显著。在不超过标准物质的有效期内,稀释混合分装后的标准物质可保存90天。  相似文献   
70.
Forest management can seriously modify the biodiversity of forest dwelling species, but the consequences are poorly known for certain taxa, particularly soil fauna, for which few studies have been published. We compared the biodiversity of dictyostelids cellular slime moulds in a managed and an unmanaged forest in the French Alps and analysed the influence of environmental factors on species richness and abundance of dictyostelids. To our knowledge, this study is the first one undertaken in the European Alps. We must better understand the influence of various environmental factors on the biodiversity of these organisms if we want to accurately define their functional role in the soil. In our study, dictyostelids showed lower levels of diversity compared to previously published results. The mean species richness of dictyostelids was marginally higher in unmanaged than in managed forests and biodiversity indices were significantly correlated with elevation and pH. This suggests that environmental factors have a predominant effect on the biodiversity of dictyostelids and that the effect of forest management is secondary.  相似文献   
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