全文获取类型
收费全文 | 8647篇 |
免费 | 72篇 |
国内免费 | 110篇 |
专业分类
林业 | 583篇 |
农学 | 189篇 |
基础科学 | 166篇 |
988篇 | |
综合类 | 2131篇 |
农作物 | 307篇 |
水产渔业 | 138篇 |
畜牧兽医 | 3934篇 |
园艺 | 153篇 |
植物保护 | 240篇 |
出版年
2024年 | 25篇 |
2023年 | 105篇 |
2022年 | 94篇 |
2021年 | 92篇 |
2020年 | 91篇 |
2019年 | 104篇 |
2018年 | 110篇 |
2017年 | 70篇 |
2016年 | 86篇 |
2015年 | 60篇 |
2014年 | 149篇 |
2013年 | 151篇 |
2012年 | 525篇 |
2011年 | 620篇 |
2010年 | 251篇 |
2009年 | 234篇 |
2008年 | 624篇 |
2007年 | 616篇 |
2006年 | 502篇 |
2005年 | 499篇 |
2004年 | 478篇 |
2003年 | 448篇 |
2002年 | 419篇 |
2001年 | 305篇 |
2000年 | 340篇 |
1999年 | 155篇 |
1998年 | 51篇 |
1997年 | 43篇 |
1996年 | 41篇 |
1995年 | 56篇 |
1994年 | 73篇 |
1993年 | 99篇 |
1992年 | 85篇 |
1991年 | 79篇 |
1990年 | 75篇 |
1989年 | 87篇 |
1988年 | 99篇 |
1987年 | 68篇 |
1986年 | 77篇 |
1985年 | 70篇 |
1984年 | 59篇 |
1983年 | 51篇 |
1982年 | 50篇 |
1981年 | 45篇 |
1980年 | 42篇 |
1979年 | 33篇 |
1978年 | 18篇 |
1959年 | 29篇 |
1958年 | 20篇 |
1957年 | 25篇 |
排序方式: 共有8829条查询结果,搜索用时 16 毫秒
101.
文章对多浪羊初乳及常乳营养成分进行了分析。结果表明:多浪羊羊奶营养丰富,常乳中蛋白质、脂肪、乳糖、铁、锌、钙、磷、维生素B1、维生素B2、维生素E的含量分别为5.79%、6.40%、4.56%、0.36mg/100g、6.7mg/100g、195.86mg/100g、146.0mg/100g、0.043mg/100g、0.214mg/100g。初乳中蛋白质、脂肪、乳糖、铁、锌、钙、磷、维生素B1、维生素B2、维生素E的含量分别为常乳的3.6、2.0、0.4、2.6、7.0、1.1、3.0、17.9、13.5倍。氨基酸含量丰富,富含人体所需的必需氨基酸。 相似文献
102.
肉用绵羊冷冻精液技术的应用研究对提高优质种公羊利用率和充分发挥优良个体在绵羊改良工作中起到重要的作用.目前,绵羊颗粒冷冻精液仍没有广泛地推广应用.新疆是一个养羊大省,养羊业已成为农民增收的支柱产业,但目前羊的品种改良工作还跟不上发展需要.主要原因是优良品种的种羊价格高,农民买不起.利用优良品种的冷冻精液改良土种羊是最好的途径,可获得显著经济效益,越来越受到广大畜牧工作者的重视和养羊专业户的欢迎.因此,2009年11月底我们在新和县开展了肉用羊颗粒冷冻精液生产. 相似文献
103.
学角度而言,鸡蛋就像一个天然容器,它能够提供胚胎宫外发育所需的营养物质和生物活性分子[1,2].这意味着,鸡蛋里面必须包含能使生殖细胞发育为成熟小鸡的所有成分.鸡蛋中含有胚胎发育所需的维生素和蛋白质(蛋清和蛋黄),脂肪(蛋黄)和矿物质(蛋壳).鸡蛋也是人类不可缺少的食物.鸡蛋中氨基酸比例均衡有利于胃肠道吸收,因而营养价值很高[3,4]. 相似文献
104.
为评价莜麦(Avena nuda L.)用作肉用仔鸡饲料成份的可能性,进行两个试验。试验1测定了莜麦的化学组分(见表),代谢能。莜麦的燕麦蛋白含量较低,但其氨基酸组成和矿物质含量优于玉米。莜麦的脂肪含量(6.85%)中有30.9%为亚油酸,这高于大多数谷物,并使其具有较高的代谢能值:3.18千 相似文献
105.
106.
107.
乌兰花拉 《畜牧兽医科技信息》2021,(3):107-107
在养羊过程中,如果没有做好饲养管理以及防疫工作,会导致多种传染病频发.不仅影响羊的生长发育以及繁殖性能,严重时可能会造成死亡,引起疫病的大范围传播,给养殖场的经济损失.本文介绍了一些常见羊传染病的预防和治疗措施,供参考. 相似文献
108.
Spirocerca lupi infection in the dog: a review 总被引:2,自引:0,他引:2
van der Merwe LL Kirberger RM Clift S Williams M Keller N Naidoo V 《Veterinary journal (London, England : 1997)》2008,176(3):294-309
Spirocercosis is a disease occurring predominantly in Canidae, caused by the nematode Spirocerca lupi. Typical clinical signs are regurgitation, vomiting and dyspnoea. The life-cycle involves an intermediate (coprophagous beetle) and a variety of paratenic hosts. Larvae follow a specific migratory route, penetrating the gastric mucosa of the host, migrating along arteries, maturing in the thoracic aorta before eventually moving to the caudal oesophagus. Here the worm lives in nodules and passes larvated eggs which can be detected using zinc sulphate faecal flotation. Histologically, the mature oesophageal nodule is composed mostly of actively dividing fibroblasts. Spirocerca lupi-associated oesophageal sarcomas may occur and damage to the aorta results in aneurysms. A pathognomonic lesion for spirocercosis is spondylitis of the thoracic vertebrae. Primary radiological lesions include an oesophageal mass, usually in the terminal oesophagus, spondylitis, and undulation of the aortic border. Contrast radiography and computed tomography are helpful additional emerging modalities. Oesophageal endoscopy has a greater diagnostic sensitivity than radiography. Endoscopic biopsies are not sensitive for detecting neoplastic transformation. Doramectin is the current drug of choice, effectively killing adult worms and decreasing egg shedding. Early diagnosis of infection is still a challenge and to date no ideal regimen for prophylaxis has been published. 相似文献
109.
German AJ Holden S Bissot T Morris PJ Biourge V 《Journal of Feline Medicine and Surgery》2008,10(5):452-459
Obesity is one of the most common medical diseases in cats, but there remains little information on success of weight loss regimes in obese client-owned cats. No information currently exists on body composition changes during weight loss in clinical cases. Twelve obese client-owned cats undertook a weight loss programme incorporating a high-protein low fat diet. Body composition was quantified by dual-energy X-ray absorptiometry, before and after weight loss. Mean (+/-standard deviation) weight loss was 27+/-6.8% of starting weight, and mean rate of weight loss was 0.8+/-0.32% per week. Mean energy allocation during weight loss was 32+/-7.0 kcal/kg target weight. Mean composition of tissue lost was 86:13:1 (fat:lean:bone mineral). The proportion of lean tissue loss was positively associated with overall percentage of weight loss (simple linear regression, r(2)=44.2%, P=0.026). Conventional weight loss programmes produce safe weight loss, but lean tissue loss is an inevitable consequence in cats that lose significant proportions of their starting body weight. 相似文献
110.
The objectives of this study were 1) to estimate the heritability of lamb survival and growth in the Scottish Blackface breed; 2) to examine the relationship between lamb survival and live BW; and 3) to investigate the possibility of using lamb survival in a breeding program for this breed. The data used for the analyses contained information about survival and live BW at different ages on 4,459 animals. The records were collected from 1988 to 2003 in a Scottish Blackface flock. Live BW was recorded every 4 wk from birth to 24 wk. Survival was defined either by perinatal or postnatal mortality (up to weaning at 12 wk), or as cumulative survival to 1, 4, 8, and 12 wk. The pedigree file comprised 1,416 dams and 178 sires. A sire model was used to estimate genetic parameters for binary survival traits. Heritabilities of BW traits, and phenotypic and genetic correlations between BW and between survival and BW were estimated by fitting an animal model. Further, correlations of survival with live BW were estimated by using a Markov chain Monte Carlo threshold model, implemented by Gibbs sampling. The heritability estimates for cumulative lamb survival declined from birth onward (from 0.33 to 0.08), and postnatal survival had a heritability of 0.01. The direct and maternal heritabilities for BW traits ranged from 0.08 to 0.26 and from 0.06 to 0.21, respectively, whereas the maternal environmental component was between 0.04 and 0.16. The genetic correlations between BW traits at different ages were high. The genetic and phenotypic correlations between survival and BW were always positive (ranging from 0.04 to 0.54), so there was no antagonism between these traits. Therefore, it is possible to simultaneously improve both survival and live BW in a breeding program for this breed. 相似文献