全文获取类型
收费全文 | 2927篇 |
免费 | 216篇 |
国内免费 | 184篇 |
专业分类
林业 | 275篇 |
农学 | 132篇 |
基础科学 | 112篇 |
176篇 | |
综合类 | 1219篇 |
农作物 | 156篇 |
水产渔业 | 98篇 |
畜牧兽医 | 699篇 |
园艺 | 178篇 |
植物保护 | 282篇 |
出版年
2024年 | 18篇 |
2023年 | 61篇 |
2022年 | 69篇 |
2021年 | 127篇 |
2020年 | 110篇 |
2019年 | 143篇 |
2018年 | 71篇 |
2017年 | 84篇 |
2016年 | 150篇 |
2015年 | 94篇 |
2014年 | 175篇 |
2013年 | 174篇 |
2012年 | 220篇 |
2011年 | 219篇 |
2010年 | 138篇 |
2009年 | 166篇 |
2008年 | 128篇 |
2007年 | 127篇 |
2006年 | 133篇 |
2005年 | 122篇 |
2004年 | 95篇 |
2003年 | 82篇 |
2002年 | 57篇 |
2001年 | 78篇 |
2000年 | 58篇 |
1999年 | 77篇 |
1998年 | 64篇 |
1997年 | 41篇 |
1996年 | 25篇 |
1995年 | 35篇 |
1994年 | 27篇 |
1993年 | 24篇 |
1992年 | 20篇 |
1991年 | 18篇 |
1990年 | 19篇 |
1989年 | 20篇 |
1988年 | 14篇 |
1987年 | 16篇 |
1986年 | 2篇 |
1985年 | 3篇 |
1983年 | 1篇 |
1982年 | 6篇 |
1981年 | 4篇 |
1980年 | 3篇 |
1979年 | 2篇 |
1978年 | 3篇 |
1977年 | 2篇 |
1955年 | 2篇 |
排序方式: 共有3327条查询结果,搜索用时 15 毫秒
991.
玉米种植环境小斑病定量表达与验证 总被引:2,自引:0,他引:2
小斑病是玉米的重要胁迫之一,在中国频繁发生,尤以夏玉米产区为主。通过对黄淮海、东华北玉米产区国家区试点发病情况与气象因素的相关性分析,筛选出影响小斑病的气象因子,即6、7、8月的日均温度为25~27℃的天数DT及日降雨量为1~25?mm的天数DR。然后用多元回归方法建立玉米种植环境小斑病Y的定量表达式,初步研究结果为Y=0.05103DT+0.04333DR。运用该式计算气象站点的小斑病值,利用ArcGIS中的地理统计分析工具,插值估计整个研究区域的发病情况,并做县级区域统计,比较黄淮海、东华北两大玉米产区的小斑病分布情况,发现黄淮海发病严重,与统计结果和实际调查吻合。该研究提出的玉米种植环境小斑病定量表达方法,能提供精确到县级的环境胁迫模拟数据,可作为品种精准推广、试验环境筛选、环境评价等所需量化信息的一种来源。 相似文献
992.
This paper, the last in a series of reviews of neurological diseases of ruminants in Australia, discusses a range of neurogenetic disorders of cattle, sheep and goats, including necrotising encephalomyelopathy, glycogen storage disorders, cerebellar abiotrophy and β-mannosidosis. They are categorised by the species and breeds in which they occur. 相似文献
993.
Disease surveillance is an integral part of most veterinary practices in Australia. The aim of this series of invited reviews is to facilitate the differential and ultimately definitive diagnosis of some of the previously known, as well as the novel and emerging, neurological disorders of ruminant livestock, which is of particular importance in the surveillance for transmissible spongiform encephalopathies. General principles of a systematic neurological examination, necropsy procedures and the neurological manifestations of systemic disease, trauma and neoplasia are described here. 相似文献
994.
Objective To describe the structure of Australia's sheep industries and the movement of sheep to enable examination of the potential for animal movements to spread disease between farms. Procedure The structure, size, marketing and movement patterns of Australian sheep farms was determined through (i) review of data published by the Australian Bureau of Statistics and Australian Bureau of Agricultural and Resource Economics, (ii) interviews with producers and saleyard managers and (iii) expert opinion. Results Twelve geographic regions are described, based on the type and extent of sheep farming in each region. Five production sectors were identified within the Australian sheep industry, with the proportion of each varying between the geographic regions. Over the past 20 years, the industry has decreased in size and contracted from the northern and central areas of Australia. Movement of sheep onto the majority (79%) of properties was limited to the introduction of less than 50 stud rams annually, although cross‐bred‐ and wether‐based farms introduced up to 2000 sheep annually; 75% of sheep movements occurred over distances less than 200 km, but stud rams moved up to 500 km. An increasing percentage of movements off farms was direct to abattoirs and over 80% of sheep sold through saleyards were purchased by abattoirs. Conclusions The majority of Australian sheep farms operate as self‐replacing enterprises and introduce few stock. In addition, most sheep movements occur over distances of less than 200 km and therefore sheep movements within Australia have only a limited potential to spread disease over larger distances. 相似文献
995.
996.
Diseases resulting from zoonotic transmission of parasites are common. Humans become infected through food, water, soil and close contact with animals. Most parasitic zoonoses are neglected diseases despite causing a considerable global burden of ill health in humans and having a substantial financial burden on livestock industries. This review aims to bring together the current data available on global burden estimates of parasitic zoonoses and indicate any changes in the trends of these diseases. There is a clear need of such information as interventions to control zoonoses are often in their animal hosts. The costs of such interventions together with animal health issues will drive the cost effectiveness of intervention strategies. What is apparent is that collectively, parasitic zoonoses probably have a similar human disease burden to any one of the big three human infectious diseases: malaria, tuberculosis or HIV in addition to animal health burden. Although the global burden for most parasitic zoonoses is not yet known, the major contributors to the global burden of parasitic zoonoses are toxoplasmosis, food borne trematode infections, cysticercosis, echinococcosis, leishmaniosis and zoonotic schistosomosis. In addition, diarrhoea resulting from zoonotic protozoa may have a significant impact. 相似文献
997.
危害建平县沙棘林生物种类及防治方法 总被引:1,自引:0,他引:1
宋小刚 《国际沙棘研究与开发》2011,9(3):34-36
近年来,建平县的沙棘人工林出现了大面积死亡现象,平均死亡率竟达58.6%,究其原因是多方面的,但是一个重要原因——大面积的纯林引发的病虫害和鼠害不容忽视。本文主要介绍了建平县境内沙棘林主要病害、虫害和鼠害的种类及其防治方法。 相似文献
998.
999.
1000.
鹿角是一种传统中药,具有广泛的药理活性和医疗保健功能,被历代医药学家所推崇,具有巨大开发利用及经济价值,本文对多种鹿角化学及药理活性方面的研究进展进行了综述,并对其开发前景提出展望,为合理开发鹿角资源,提供科学的理论依据。 相似文献