全文获取类型
收费全文 | 159429篇 |
免费 | 22733篇 |
国内免费 | 34599篇 |
专业分类
林业 | 14579篇 |
农学 | 11310篇 |
基础科学 | 11810篇 |
40686篇 | |
综合类 | 74890篇 |
农作物 | 12566篇 |
水产渔业 | 9715篇 |
畜牧兽医 | 21491篇 |
园艺 | 10040篇 |
植物保护 | 9674篇 |
出版年
2024年 | 1439篇 |
2023年 | 2774篇 |
2022年 | 5383篇 |
2021年 | 5340篇 |
2020年 | 6383篇 |
2019年 | 9274篇 |
2018年 | 7857篇 |
2017年 | 10573篇 |
2016年 | 9620篇 |
2015年 | 11670篇 |
2014年 | 11036篇 |
2013年 | 12187篇 |
2012年 | 14604篇 |
2011年 | 13735篇 |
2010年 | 12328篇 |
2009年 | 11080篇 |
2008年 | 10288篇 |
2007年 | 9868篇 |
2006年 | 8319篇 |
2005年 | 7054篇 |
2004年 | 5225篇 |
2003年 | 3890篇 |
2002年 | 3887篇 |
2001年 | 3318篇 |
2000年 | 2866篇 |
1999年 | 1860篇 |
1998年 | 1329篇 |
1997年 | 1287篇 |
1996年 | 1125篇 |
1995年 | 1186篇 |
1994年 | 1185篇 |
1993年 | 941篇 |
1992年 | 960篇 |
1991年 | 810篇 |
1990年 | 616篇 |
1989年 | 612篇 |
1988年 | 536篇 |
1987年 | 412篇 |
1986年 | 418篇 |
1985年 | 213篇 |
1984年 | 198篇 |
1983年 | 191篇 |
1982年 | 190篇 |
1981年 | 237篇 |
1980年 | 192篇 |
1979年 | 151篇 |
1978年 | 132篇 |
1965年 | 137篇 |
1964年 | 142篇 |
1955年 | 111篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
异色瓢虫成虫对豌豆修尾蚜的捕食作用 总被引:1,自引:0,他引:1
初步研究了异色瓢虫(Harmonia axyridis Pallas)的雌、雄成虫对豌豆修尾蚜(Megoura japonica Matsumura)的捕食作用,采用Holling-Ⅱ型方程功能反应模型对异色瓢虫雌、雄成虫捕食豌豆修尾蚜的效果进行拟合。结果表明,异色瓢虫雌、雄成虫的功能反应均符合Holling-Ⅱ模型。而在一定空间和相同比例猎物条件下,种内干扰会对异色瓢虫成虫捕食豌豆修尾蚜产生影响,此试验中干扰系数为1.09。 相似文献
993.
为了解广西动物源性产品中磺胺二甲嘧啶(SM2)残留情况,本研究采用磺胺二甲嘧啶化学发光酶免疫分析法(SM2-CLEIA)对2013-2017年采集的4 637份动物源性产品进行检测,共检出超标样品122份,涉及鲜乳、猪肉、水产品和猪尿,其中超标猪尿92份,SM2含量100.51~860.44 μg/kg,猪尿中抗生素残留会污染水体、土壤,再通过动植物的富集作用进入食物链,危害人类健康,应引起重视;而本次受检的水牛奶、鸡肝脏、鸭肝脏、鸭肉均合格。所有受检样品超标率逐年下降,同时规模化养殖场样品合格率高于农村散养户、超市高于农贸市场。不同年份超标样品含量以2014年最高。采用食品安全指数(IFS)对广西动物源性食品中SM2残留风险进行评估,结果均远小于1,说明在广西地区,现有的SM2残留对人体的潜在危害较低。 相似文献
995.
利用自选不育系SX330A为母本、自选恢复系SX860为父本,山西省农业科学院高粱研究所历时5年,培育出了高抗丝黑穗病酿造高粱新品种晋杂37号。该品种2015年通过山西省农作物品种审定委员会审定,审定编号:晋审杂(认)2015002。晋杂37号不仅高产、稳产、抗旱、抗倒性好,特别是对丝黑穗病表现出高抗特性,为山西省高粱酿造业的可持续发展提供了有力的保障。 相似文献
996.
LIN Yuzhen 《Journal of Landscape Research》2020,(1):45-48
Imperial city and outer city are the most important differentiation of the spatial structure of ancient Chinese capitals.The relationship between city and Guo changed from the original spatial structure mode of "respecting the west" and "sitting in the west and facing the east" to the spatial structure mode of "sitting in the north and facing the south" and the three outer cities in the east,south and west surrounding the imperial city after the Wei,Jin,Southern and Northern Dynasties,and gradually changed from the original "multi palace" system to the "single palace" system.Finally,a "heavy city" capital spatial structure with the outer city around the imperial city and the imperial city around the palace city,and the central axis of the chessboard format was formed.During the Tang and Song Dynasties,it was a period of great change in the history of feudal society in China.Through the investigation of the evolution characteristics of the spatial form of capital cities in the Tang and Song Dynasties,the track of the transformation of social ideology,political system,economic structure and many other fields in the Tang and Song Dynasties was made clear. 相似文献
997.
为发挥农机服务专业合作社在浙江省缙云县农业生产中的作用,归纳总结了缙云县农机服务专业合作社发展的现状和成效,并对该县当前农机服务专业合作社发展存在的问题进行了分析,在此基础上提出了加快发展缙云县农机服务专业合作社的相关措施建议。 相似文献
998.
LI Yan-jun SONG Shao-rui GUO Ya-fen LAN Gan-qiu CHEN Bao-jian YAN Xue-yu WU Yan-jun JIANG Qin-yang 《中国畜牧兽医》2015,42(7):1770-1776
The atherosclerosis (AS) model was prepared in Guangxi Bama mini-pig,and the atherosclerosis index (AI) was preliminarily identified in occurrence of AS to provide the basis for the preparation of related models.20 Guangxi Bama mini-pigs were randomly divided into control group and experimental group which were fed with high fat and cholesterol diet to prepare the AS model.Blood biochemical indexes were detected in the process of model preparation and the correlation between AI and the results of vascular slices was analyzed to initially draw up AI of AS.The results of vascular slices showed that the incidence rates of AS of Guangxi Bama mini-pigs in experimental group and control group were 20% and 0,respectively.The association analysis between the results of vascular slices and AI in the pathogenic Guangxi Bama mini-pigs preliminarily suggested that AI was above 3.8 and lasted for more than 3 months during the attack. 相似文献
999.
In this article, through the combination of nucleic acid probes and immune chromatography, a simple, sensitive and specific detection system——nucleic acid lateral flow immunoassay (NALFIA) for amplifing foot-and-mouth disease virus (FMDV) 3D RT-PCR products was established.An ultrasensitive nucleic acid biosensor (NAB) based on streptavidin-labeled gold nanoparticles dual labels and lateral flow strip biosensor (LFSB) were used in this system.The biotinylated goat anti-rabbit IgG was marked to the NC membrane as the alleged strip and the anti-digoxin antibody was labeled to the NC membrane to capture the digoxin probe.After assemblying gold-labeled strip and detecting RT-PCR products, the detection limit of NALFIA was 0.3×10-3 to 3×10-3 μg/μL.The NALFIA was compared with agar gel electrophoresis analysis, the results showed that the sensitivity of NALFIA was higher than agar gel electrophoresis.There was an excellent agreement between the two methods.NALFIA was a method with high sensitive, low cost and short time.In conclusion, this method provided a good alternative to detect FMDV. 相似文献
1000.