全文获取类型
收费全文 | 21802篇 |
免费 | 1145篇 |
国内免费 | 1818篇 |
专业分类
林业 | 3055篇 |
农学 | 1391篇 |
基础科学 | 2740篇 |
2307篇 | |
综合类 | 8065篇 |
农作物 | 992篇 |
水产渔业 | 357篇 |
畜牧兽医 | 1697篇 |
园艺 | 577篇 |
植物保护 | 3584篇 |
出版年
2024年 | 180篇 |
2023年 | 405篇 |
2022年 | 653篇 |
2021年 | 788篇 |
2020年 | 799篇 |
2019年 | 882篇 |
2018年 | 485篇 |
2017年 | 686篇 |
2016年 | 945篇 |
2015年 | 770篇 |
2014年 | 1247篇 |
2013年 | 1180篇 |
2012年 | 1592篇 |
2011年 | 1592篇 |
2010年 | 1155篇 |
2009年 | 1276篇 |
2008年 | 1041篇 |
2007年 | 1240篇 |
2006年 | 1119篇 |
2005年 | 862篇 |
2004年 | 814篇 |
2003年 | 739篇 |
2002年 | 581篇 |
2001年 | 587篇 |
2000年 | 462篇 |
1999年 | 403篇 |
1998年 | 331篇 |
1997年 | 329篇 |
1996年 | 259篇 |
1995年 | 257篇 |
1994年 | 214篇 |
1993年 | 179篇 |
1992年 | 177篇 |
1991年 | 142篇 |
1990年 | 135篇 |
1989年 | 91篇 |
1988年 | 75篇 |
1987年 | 44篇 |
1986年 | 22篇 |
1985年 | 8篇 |
1984年 | 3篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1980年 | 1篇 |
1979年 | 3篇 |
1978年 | 1篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1955年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 14 毫秒
51.
52.
伊维菌素控制春乏期羊狂蝇蛆病试验 总被引:1,自引:0,他引:1
目的为有效预防和控制羊狂蝇蛆病的发生。方法选用伊维菌素在羊狂蝇成虫完全消失的11月进行驱杀羊狂蝇蛆试验,并以敌敌畏熏蒸作为对照。结果在来年羊狂蝇成蝇出现之前的长达7个月的冬春枯草季节,伊维菌素组驱虫率和驱净率均保持100%,而敌敌畏熏蒸组驱虫率保持94.69%,驱净率仅保持60%。结论选择每年11月份用伊维菌素驱虫一次,可使羊在冬春季节无任何阶段羊狂蝇幼虫寄生。 相似文献
53.
非洲猪瘟在我国流行已有两年多的时间,尽管很多科研团队都在致力于非洲猪瘟疫苗的研发,但尚未有治疗措施和有效的疫苗来控制该病。因此现阶段“生物安全”是控制非洲猪瘟最为有效,也是唯一的方法。文章总结出目前规模化猪场常见的感染风险有“人员流动、物品流动、车辆流动、水源流动、猪群流动”(即“五流”),并提出严格控制“五流”的生物安全防控措施(即“五流”生物安全防控),以减少外界病原与猪只的接触,稀释病原浓度,降低病原载量,最大程度地降低规模化养猪场感染疾病的风险。为当前规模化猪场建立有效的生物安全措施提供参考。 相似文献
54.
55.
欧美牛病毒性腹泻防控措施及对我国的启示 总被引:1,自引:0,他引:1
牛病毒性腹泻是牛的重要疫病,导致产奶量下降、肉产量降低、繁殖障碍、生长迟缓、继发其他病原几率增加甚至死亡等,给养牛业造成较大的经济损失。欧美国家在牛病毒性腹泻防控方面形成了一套行之有效的方法,有效地控制并逐步根除了BVD。借鉴欧美牛病毒性腹泻防控策略可对我国该病的防制提供一定的指导。 相似文献
56.
Yuichi Kuroiwa Ryo Ando Kenichiro Kasahara Mariko Nagatani Seiki Yamakawa Shuzo Okazaki 《Journal of toxicologic pathology》2013,26(2):227-230
Historical control data of tumor incidence were collected from the control groups (215
animals of each sex) in four recent carcinogenicity studies that were started between 2005
to 2009 (terminally sacrificed between 2007 and 2011) at BoZo Research Center Inc.
(Gotemba, Shizuoka, Japan) using Fischer 344 rats (F344/DuCrlCrlj). These data were
compared to the previous historical control data (from 1990 to 2004, previously reported)
in the same facility. In the results, the incidence of C-cell adenoma in the thyroid
tended to increase in both sexes in recent years (30.8% for males and 24.4% for females in
2005-2009) as compared with the previous data (17.4% and 20.1% for males and 11.5% and
11.8% for females in 1990–1999 and 2000–2004, respectively). In addition, the incidences
of pancreatic islet cell adenoma in males and uterine adenocarcinoma tended to increase
from around 2000 and remained high in recent years (incidences of islet cell adenoma in
males of 10.5%, 17.1% and 20.5% in 1990–1999, 2000–2004 and 2005–2009; incidences of
uterine adenocarcinoma of 3.3%, 12.0% and 13.5% in 1990–1999, 2000–2004 and 2005–2009,
respectively). There was no apparent difference in the incidence of other tumors. 相似文献
57.
58.
An investigation was carried out into an outbreak of respiratory disease complex (RDC) in 3641 Menz and Awassi×Menz cross sheep in Central Ethiopia between 1998 and 1999 by clinical, serological, microbiological, post-mortem and histopathological examinations. The monthly incidence of RDC varied from 2.8% to 4.0% and the prevalence was as high as 17%. The case fatality rate was 18%, despite culling of sick sheep. Over 76% of the morbidity occurred in adults, followed by 19% among weaners. Similarly, 62% of the mortality was in adults. However, 27% of the mortality occurred in lambs despite the low morbidity in the group. Significant breed and age differences were seen in the morbidity and mortality rates (p<0.05). Clinical signs, gross and microscopic lesions and serological and bacteriological examinations showed an interplay of several causes of the RDC, including pestes des petits ruminants (PPR) (72.3%, serologically confirmed), lung worms, maedi-visna, bacterial bronchopneumonia (staphylococcal and streptococcal), enzootic pneumonia and some fungal infections. Cold temperatures, which may be as low as –8.5°C at night, are major predisposing factors along with managemental stresses. Vaccination of animals with a homologous PPR vaccine appeared to decrease dramatically the occurrence of the disease, showing that PPR played an important role in the outbreak. Several of the pathogens do not appear to be individually capable of causing the respiratory disease. Appropriate strategies for the prevention of RDC are suggested. 相似文献
59.
Epidemiology and control of Menangle virus in pigs 总被引:6,自引:0,他引:6
Kirkland PD Love RJ Philbey AW Ross AD Davis RJ Hart KG 《Australian veterinary journal》2001,79(3):199-206
OBJECTIVE: To describe the epidemiology and eradication of Menangle virus infection in pigs. DESIGN: Field observations and interventions, structured and unstructured serological surveys, prospective and cross-sectional serological studies and laboratory investigations. PROCEDURE: Serum samples were collected from pigs at a 2600-sow intensive piggery in New South Wales that experienced an outbreak of reproductive disease in 1997. Serum samples were also collected from piggeries that received pigs from or supplied pigs to the affected piggery and from other piggeries in Australia. Serum and tissue samples were collected from pigs at piggeries experiencing reproductive disease in New South Wales. Sera and faeces were collected from grey-headed flying foxes (Pteropus poliocephalus) in the region of the affected piggery. Serum samples were tested for neutralising antibodies against Menangle virus. Virus isolation was attempted from faeces. RESULTS: Following the outbreak of reproductive disease, sera from 96% of adult pigs at the affected piggery, including sows that produced affected litters, contained neutralising antibodies against Menangle virus. Neutralising antibodies were also detected in sera from 88% of finisher pigs at two piggeries receiving weaned pigs from the affected piggery. No evidence of Menangle virus infection was found in other piggeries in Australia. In cross-sectional studies at the affected piggery, colostral antibodies were undetectable in most pigs by 14 to 15 weeks of age. By slaughter age or entry to the breeding herd, 95% of pigs developed high antibody titres (> or = 128) against Menangle virus in the virus neutralisation test. Menangle virus was eradicated from the affected piggery following a program of serological testing and segregation. Neutralising antibodies against Menangle virus were also detected in P poliocephalus from two colonies in the vicinity of the affected piggery. Two piggery workers were infected with Menangle virus. There was no evidence of infection in cattle, sheep, birds, rodents, feral cats and a dog at the affected piggery. CONCLUSIONS: Serological evidence of infection with Menangle virus was detected in pigs at a piggery that had experienced reproductive disease, in pigs at two associated piggeries and in fruit bats in the region of the piggery. Two humans were infected. The mode of transmission between pigs is unknown, but spread by faecal or urinary excretion is postulated. This virus can be eradicated by the segregation of pigs into discrete age groups. 相似文献
60.