全文获取类型
收费全文 | 178篇 |
免费 | 13篇 |
国内免费 | 1篇 |
专业分类
林业 | 9篇 |
农学 | 3篇 |
基础科学 | 3篇 |
4篇 | |
综合类 | 29篇 |
农作物 | 6篇 |
水产渔业 | 5篇 |
畜牧兽医 | 121篇 |
园艺 | 2篇 |
植物保护 | 10篇 |
出版年
2023年 | 2篇 |
2021年 | 3篇 |
2020年 | 3篇 |
2019年 | 2篇 |
2018年 | 3篇 |
2017年 | 5篇 |
2016年 | 9篇 |
2015年 | 5篇 |
2014年 | 5篇 |
2013年 | 10篇 |
2012年 | 4篇 |
2011年 | 6篇 |
2010年 | 5篇 |
2009年 | 7篇 |
2008年 | 3篇 |
2007年 | 10篇 |
2006年 | 14篇 |
2005年 | 6篇 |
2004年 | 1篇 |
2003年 | 8篇 |
2002年 | 2篇 |
2001年 | 4篇 |
2000年 | 5篇 |
1999年 | 5篇 |
1998年 | 4篇 |
1997年 | 15篇 |
1996年 | 3篇 |
1995年 | 6篇 |
1994年 | 4篇 |
1993年 | 5篇 |
1992年 | 6篇 |
1991年 | 3篇 |
1990年 | 1篇 |
1989年 | 4篇 |
1988年 | 3篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1981年 | 1篇 |
1976年 | 1篇 |
1973年 | 1篇 |
1970年 | 1篇 |
1969年 | 1篇 |
1967年 | 1篇 |
排序方式: 共有192条查询结果,搜索用时 15 毫秒
1.
SUMMARY Twenty-four of 57 calves fed a diet containing 33% cotton seed meal (CSM) died between 7 and 15 weeks of age. Initial deaths were not accompanied by premonitory signs, but after CSM withdrawal most calves developed rough coats, anorexia, weakness, ascites and subcutaneous oedema. Those that died had large volumes of serous fluid in the body cavities, hard livers of ‘nutmeg’ appearance, and pulmonary congestion. Histopathologically the livers showed periacinar necrosis in acute cases and periacinar fibrosis in chronic cases. Lungs from several calves had oedema, haemosiderosis and fibrosis in some pulmonary vessels. Atrophy of myocardial fibres was present in most cases. The concentration of free gossypol in the diet was 100 to 220 mg/kg. Ante-mortem and post-mortem findings supported a diagnosis of gossypol poisoning. The deaths continued for 4 weeks after withdrawal of CSM from the diet. 相似文献
2.
RO Pinho BS Camilo DMA Lima FAC Villadiego JCM Vergara HH Shiomi RE Cardoso PS Lopes JD Guimarães 《Reproduction in domestic animals》2018,53(2):393-400
The objective was to study the use of ultrasound as a complementary test in the breeding soundness evaluation in male pigs and study the pattern of echogenicity of the testicular parenchyma in boars of different racial groups. Twenty‐six adult boars from four different racial groups were used, 10 from the Piau breed (group 1), four from the commercial and finishing group (group 2), six Pietrain breed (group 3) and six from the Duroc breed (group 4). All animals were evaluated for breeding soundness evaluation and the ultrasound examination of the testicles. The groups of animals that were evaluated showed no difference in the main semen parameters that were evaluated, except for the sperm volume, concentration of the ejaculated sperm and the supravital staining; the lowest figures were for the animals from the Piau breed (group 1). In relation to the testicular biometrics, Duroc animals (group 4) had a greater scrotal width compared to the other groups. But when we assessed the intensity of pixels of the testicles, there was a difference between groups. The groups 2 (finishing animals), 3 (Pietrain) and 4 had no difference between themselves. Group 3 had greater pixel intensity in relation to group 1. Of the 26 animals studied, five showed an abnormality during ultrasound evaluation, like hydrocele, hyperechoic mass in the testicular parenchyma, cyst in the head of the epididymis and the presence of fluid in the head and tail of the epididymis. The various animal groups studied did not differ in the principal reproductive parameters evaluated, showing that despite the great variability of reproductive traits between breeds and within the same breed, the breeding soundness evaluation, the more complete it is, is essential for the selection of breeders and the ultrasonography of the reproductive system becomes an important addition in this examination. 相似文献
3.
Validation of the Accutrend Plus point‐of‐care triglyceride analyzer in horses,ponies, and donkeys 下载免费PDF全文
4.
基于地基激光雷达的叶倾角分布升尺度方法研究 总被引:1,自引:0,他引:1
地基激光雷达因其具有穿透力强,能够提取植被冠层三维结构信息的优势,是提取植被叶倾角分布(Leaf angle distribution,LAD)的理想数据源,因此将地基激光雷达数据与遥感影像结合获取大尺度叶倾角分布结果颇具潜力。以河北省保定市北部4个县为研究区,利用10个玉米样地的地基激光雷达数据提取叶倾角分布结果,使用主成分正变换提取玉米实测叶倾角分布数据中信息量最大的前3个主成分,再利用神经网络模型对所提取的主成分与Landsat8反射率数据结合建立关系模型,然后将训练好的模型应用于整个研究区进行升尺度转换,最后通过主成分逆变换,得到升尺度后平均叶倾角(Mean tilt angle,MTA)结果。对升尺度后LAD与实测LAD及升尺度后MTA与实测MTA进行交叉验证,结果表明,升尺度MTA与实测MTA的验证精度(R2)为0.786 2,均方根误差(RMSE)为3.04°。该结果表明,使用提取主成分方法建立光谱数据与叶倾角分布的关系模型从而达到升尺度转换的目的具有可行性,模拟精度较高,且误差较小。 相似文献
5.
6.
7.
We evaluated whether new information could be drawn from additional data collection and unconventional statistical analyses of an on-farm trial. First, we compared a conventional sampling method using a biomass estimate of weed abundance to repeated visual assessment of the percentage ground cover of weeds. The biomass was sampled once after the treatment, whereas the ground cover was repeatedly sampled once before weed control plus several occasions after weed control. Second, we contrasted the outcomes from analysis of variance ( anova ), taking samples from a single point in time with repeated measures (rm) anova and a multivariate method. As the outcomes and conclusions drawn were relatively similar, we conclude that the ground cover estimate of weed abundance was as reliable as the biomass estimate. The rm anova enabled us to follow the temporal trend in response to treatments in the most abundant species, including possible initial differences. Multivariate analysis went even further, by clearly displaying species-wise responses and treatment selectivity. 相似文献
8.
9.
为研究中国美利奴羊不同甘露(聚)糖结合凝集素(MBL)浓度感染绵羊肺炎支原体(MO)的免疫因子水平变化,本研究选择血清中MBL高、低浓度的绵羊各6只(感染组和对照组各3只),感染组人工感染MO,分别在人工感染前和感染后不同时间,采用荧光定量PCR法检测血液中血清因子及补体表达水平。结果显示,不同MBL浓度的绵羊人工感染后MBL m RNA水平呈下降趋势,MBL高浓度促炎因子IL-2和IFN-γ的m RNA表达水平较高,抗炎因子IL-4的m RNA表达水平在感染后1 d升高,此后开始下降,而IL-4的m RNA水平在14 d后有所升高;MBL低浓度羊感染后其TNF-α的m RNA水平显著升高,随炎症的缓解,逐渐降低;补体C1和C3的m RNA在感染后表现出不同的变化,MO感染可以激活补体途径。本研究结果表明,低血清MBL浓度与绵羊支原体肺炎具有一定的相关性,MBL不同浓度组之间其IL-2、IL-4、TNF-α、IFN-γ、补体C1、C3水平存在差异,低浓度MBL的绵羊更易发生比较严重的炎症反应。 相似文献
10.
K. Birkmann H.K. Junge E. Maischberger M. Wehrli Eser C.C. Schwarzwald 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2014,28(3):925-933