全文获取类型
收费全文 | 25203篇 |
免费 | 1318篇 |
国内免费 | 1870篇 |
专业分类
林业 | 3600篇 |
农学 | 1519篇 |
基础科学 | 2993篇 |
2516篇 | |
综合类 | 10089篇 |
农作物 | 1104篇 |
水产渔业 | 395篇 |
畜牧兽医 | 1863篇 |
园艺 | 646篇 |
植物保护 | 3666篇 |
出版年
2024年 | 195篇 |
2023年 | 448篇 |
2022年 | 700篇 |
2021年 | 864篇 |
2020年 | 879篇 |
2019年 | 988篇 |
2018年 | 504篇 |
2017年 | 745篇 |
2016年 | 1044篇 |
2015年 | 904篇 |
2014年 | 1619篇 |
2013年 | 1483篇 |
2012年 | 2053篇 |
2011年 | 1933篇 |
2010年 | 1400篇 |
2009年 | 1500篇 |
2008年 | 1217篇 |
2007年 | 1404篇 |
2006年 | 1249篇 |
2005年 | 980篇 |
2004年 | 916篇 |
2003年 | 831篇 |
2002年 | 626篇 |
2001年 | 650篇 |
2000年 | 499篇 |
1999年 | 421篇 |
1998年 | 349篇 |
1997年 | 345篇 |
1996年 | 269篇 |
1995年 | 261篇 |
1994年 | 218篇 |
1993年 | 180篇 |
1992年 | 178篇 |
1991年 | 145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 12 毫秒
41.
42.
蜂蟹螨(Varroa destructor)对福化利抗药性及其防治的研究 总被引:1,自引:0,他引:1
建立培养皿药膜法进行蜂蟹螨福化利(Fluvalinate)抗药浓度检测方法。分别以福化利浓度为0、12.5、25、50、100mg/L进行台湾5处蜂场蜂蟹螨抗福化利剂量调查,经回归分析,计算LC50之浓度介于23.75~79.25mg/L之间,比意大利抗性螨385~857mg/L仍低很多,显示抗药性尚未大幅增加。以隔落螨法防治蜂蟹螨平均每日可捕捉44.7~49.1只。比较隔落螨法、割雄蜂蛹加隔落螨法、蚁酸加隔落螨法、福化利防治法的效果,当蜂蟹螨密度不高时,可采用隔落螨法或加割雄蜂蛹方式进行防治,蜂蟹螨密度高时,可先以福化利、蚁酸进行1~2次防治,再配合隔落螨法,将可达到长期防治效果。 相似文献
43.
对青蒿素及其衍生物的作用机理及近年来其在防治鸡球虫病的应用做了较详细的综述,以期为其在防治鸡球虫病中的应用提供参考。青蒿素被用于治疗疟疾已有几百年的历史,它还具有治疗血吸虫、腹泻及清热、镇静安神的作用,但其在兽医临床中的应用还是一个新领域。 相似文献
44.
The control of Amaranthus spp. and the influence thereof on Digitaria eriantha during the season of establishment. Chemical control of Amaranthus spp. in newly established Smuts finger grass (D. eriantha) was investigated. A mixture of 800 ml 2,4‐D Amine+1200 ml Atrazine per ha was applied. This treatment produced a total yield of 6,1 t/ha of which 4,6 t/ha (75,4%) consisted of Smuts finger grass. The rest were weeds. In the case of no chemical control total yield amounted to 4,5 t/ha dry matter of which only 0,7 t/ha (15,5%) was Smuts finger grass. Chemical control clearly had economic advantages. 相似文献
45.
S.R. Porter C. Saegerman G. Van Galen C. Sandersen C. Delguste H. Guyot H. Amory 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2008,22(6):1411-1416
Background: Endocarditis is a rare heart condition with variable clinical expressions in equids. Risk factors for this disease are incompletely understood. Objective: Describe risk factors for endocarditis in equids. Animals: One hundred and fifty‐three equids admitted to Liège University, 9 diagnosed with endocarditis and 144 free from endocarditis but admitted to the hospital with a differential diagnosis including this disease. Methods: Retrospective case‐control study. Results: Equids with endocarditis were significantly younger (mean age = 4.84 ± 5.74 years) than control equids (mean age = 10.8 ± 7.73 years) (P= .01). No sex or breed predisposition was observed. Animals with hyperthermia (odds ratio [OR] = 24.4; confidence interval [CI] = 1.40–428), synovial distension (OR = 13.4; CI = 3.00–59.8), lameness (OR = 6.52; CI = 1.63–26.1), hyperglobulinemia (OR = 26.4; CI = 3.03–229), hypoalbuminemia (OR = 11.4; CI = 1.34–96.8), hyperfibrinogenemia (OR = 9.81; CI = 1.16–82.7), or leukocytosis (OR = 7.12; CI = 1.40–36.4) presented a significantly higher risk of having endocarditis than control horses. The presence of two of the clinical signs mentioned above significantly increased the probability of a diagnosis of endocarditis (P≤ .05). Conclusions and Clinical Importance: Age is associated with equine endocarditis. The diagnostic value of certain clinical signs and abnormalities in blood parameters in this disease are described. 相似文献
46.
Statistical control charts were used to detect process change in pig production. Two charts were tested to detect small deviations in production processes: the cumulative sum (CUSUM) control chart and the exponentially weighted moving average (EWMA) control chart. A Monte-Carlo simulation was used for developing an optimal design of the EWMA and the CUSUM charts. The traits piglets born in total and the return to oestrus rate were considered. Over a given time period, small shifts were purposely implemented to test the performance of the charts. The average time to signal (ATS) and false positive rate (FPR) were taken as classification parameters to evaluate the performance of the charts. All shifts in the number of piglets born in total were detected with CUSUM and EWMA control charts. The trait piglets born in total showed an ATS ranging from 1.3 (FPR = 33.5%) to 6.8 weeks (FPR = 1.2%) using the CUSUM chart. The EWMA chart presented an ATS which ranged between 2.0 (FPR = 14.9%) and 6.3 (FPR = 1.9%) weeks. The application of the CUSUM to the return to oestrus rate resulted in an ATS of 2.6 (FPR = 38.3%) to 15.6 weeks (FPR = 3.0%) and the EWMA chart produced a signal between 4.1 (FPR = 14.5%) and 16.4 weeks (FPR = 1.4%). Both charts appear to be useful tools for tracking commercial swine farm processes and detecting emerging change in process performance. 相似文献
47.
西藏“一江两河”流域中部草地沙漠化与防治 总被引:3,自引:0,他引:3
据1:3.5×10^4假彩色红外航空像片室内判读与野外调查,本区沙漠化草地可分为中度及轻度两种,面积12.823万hm^2,导致草地沙漠化的人为因素主要是超载过牧,樵柴,放牧制度不合理等,草地沙漠化防治可采取生物,管理及工程等措施。 相似文献
48.
范良志 《畜牧兽医科学(电子版)》2021,(5):159-160
非洲猪瘟疫情已经成为制约养猪业发展的头号杀手,生猪稳产保供任务引起高度重视,因此,防控非洲猪瘟疫情是各级政府和养猪企业的重点工作之一,该文主要论述规模化猪场非洲猪瘟防控措施。 相似文献
49.
50.