全文获取类型
收费全文 | 6295篇 |
免费 | 608篇 |
国内免费 | 606篇 |
专业分类
林业 | 853篇 |
农学 | 341篇 |
基础科学 | 674篇 |
1280篇 | |
综合类 | 2165篇 |
农作物 | 144篇 |
水产渔业 | 414篇 |
畜牧兽医 | 1090篇 |
园艺 | 124篇 |
植物保护 | 424篇 |
出版年
2024年 | 32篇 |
2023年 | 168篇 |
2022年 | 293篇 |
2021年 | 380篇 |
2020年 | 358篇 |
2019年 | 366篇 |
2018年 | 258篇 |
2017年 | 339篇 |
2016年 | 341篇 |
2015年 | 346篇 |
2014年 | 402篇 |
2013年 | 446篇 |
2012年 | 547篇 |
2011年 | 550篇 |
2010年 | 425篇 |
2009年 | 377篇 |
2008年 | 312篇 |
2007年 | 333篇 |
2006年 | 237篇 |
2005年 | 213篇 |
2004年 | 172篇 |
2003年 | 117篇 |
2002年 | 93篇 |
2001年 | 64篇 |
2000年 | 54篇 |
1999年 | 48篇 |
1998年 | 44篇 |
1997年 | 34篇 |
1996年 | 30篇 |
1995年 | 42篇 |
1994年 | 24篇 |
1993年 | 9篇 |
1992年 | 13篇 |
1991年 | 11篇 |
1990年 | 10篇 |
1989年 | 3篇 |
1988年 | 3篇 |
1987年 | 4篇 |
1986年 | 3篇 |
1985年 | 3篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1975年 | 1篇 |
1962年 | 2篇 |
排序方式: 共有7509条查询结果,搜索用时 218 毫秒
81.
82.
83.
ACVIM Consensus Statement on Therapeutic Antimicrobial Use in Animals and Antimicrobial Resistance 下载免费PDF全文
J.S. Weese S. Giguère L. Guardabassi P.S. Morley M. Papich D.R. Ricciuto J.E. Sykes 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2015,29(2):487-498
The epidemic of antimicrobial resistant infections continues to challenge, compromising animal care, complicating food animal production and posing zoonotic disease risks. While the overall role of therapeutic antimicrobial use in animals in the development AMR in animal and human pathogens is poorly defined, veterinarians must consider the impacts of antimicrobial use in animal and take steps to optimize antimicrobial use, so as to maximize the health benefits to animals while minimizing the likelihood of antimicrobial resistance and other adverse effects. This consensus statement aims to provide guidance on the therapeutic use of antimicrobials in animals, balancing the need for effective therapy with minimizing development of antimicrobial resistance in bacteria from animals and humans. 相似文献
84.
85.
为提高低空间分辨率遥感影像在卫星林火监测部门的应用质量,获取更准确的火灾信息,制作可视效果更好、便于基层部门使用的卫星林火监测图像。本研究以2013年2月6日云南省大理市黄家村森林火灾为背景,研究了一种基于亚像元分解与增强技术的卫星林火监测图像制作技术。结果表明,通过亚像元分解与增强技术,对空间分辨率低的气象卫星遥感图像进行处理,可得到空间分辨率为30 m的图像产品,能够将低分辨率遥感影像处理成超分辨率的遥感影像图像。该技术可应用于林火监测部门发布相关的监测图像。 相似文献
86.
以福建省顺昌县的杉木纯林、毛竹纯林、杉木马尾松混交林、杉木阔叶混交林、阔叶林等5块样地为对象,从结构性、功能性和抗干扰性等3个方面出发,筛选出15个指标,并利用主成分分析(PCA)实现了研究区森林健康评价。结果显示:福建省顺昌县杉木纯林、毛竹纯林、杉木马尾松混交林、杉木阔叶混交林、阔叶林等5块样地的森林健康综合指数值依次为-0.27、-0.25、0.35、0.53和-0.01,从优到次的排名为:杉木阔叶混交林、杉木马尾松混交林、阔叶林、毛竹纯林、杉木纯林。 相似文献
87.
88.
The ecological environment in Central Asia is vulnerable to pressure from human activity due to the physical geography and climatic fragility of this region. A set of indicators suitable for the future assessment of this pressure needs to be proposed. Thirty‐six topsoil samples (0–5 cm) were collected from roadsides in a suburban region of Bishkek, the capital of the Kyrgyz Republic in Central Asia, and a risk assessment of anthropogenically disturbed potentially toxic elements (PTEs) was systematically conducted with classic statistical methods. The results of detrended correspondence analysis and principal component analysis clearly showed that topsoil samples with high contents of PTEs (Pb, Zn and Cu) were strongly affected by traffic within a distance threshold of 200 m and that anthropogenic effects decreased significantly with increasing distance from the highway. The enrichment factor and anthropogenic contribution for Pb were the highest among the three PTEs, with average values of 2.0% and 47.4%, respectively, suggesting enrichment. However, the results of the human health risk assessment also indicated that noncarcinogenic risks did not occur for any of the anthropogenic PTEs. The reported method provides a new systematic pathway to reveal anthropogenic influences on the geochemical composition of soil. The conclusions of this work will be highly valuable as important guidelines for agriculture, and the results of the PTE contents will provide a scientific basis for soil collection in future studies. 相似文献
89.
90.