全文获取类型
收费全文 | 73282篇 |
免费 | 4132篇 |
国内免费 | 32篇 |
专业分类
林业 | 3173篇 |
农学 | 2397篇 |
基础科学 | 466篇 |
8668篇 | |
综合类 | 12016篇 |
农作物 | 2818篇 |
水产渔业 | 3522篇 |
畜牧兽医 | 38583篇 |
园艺 | 835篇 |
植物保护 | 4968篇 |
出版年
2018年 | 966篇 |
2017年 | 1073篇 |
2016年 | 1000篇 |
2015年 | 845篇 |
2014年 | 1046篇 |
2013年 | 2745篇 |
2012年 | 1943篇 |
2011年 | 2267篇 |
2010年 | 1533篇 |
2009年 | 1558篇 |
2008年 | 2321篇 |
2007年 | 2220篇 |
2006年 | 2034篇 |
2005年 | 1969篇 |
2004年 | 1846篇 |
2003年 | 1989篇 |
2002年 | 1806篇 |
2001年 | 2239篇 |
2000年 | 2190篇 |
1999年 | 1748篇 |
1998年 | 714篇 |
1997年 | 776篇 |
1996年 | 685篇 |
1995年 | 865篇 |
1994年 | 734篇 |
1993年 | 734篇 |
1992年 | 1493篇 |
1991年 | 1634篇 |
1990年 | 1602篇 |
1989年 | 1606篇 |
1988年 | 1493篇 |
1987年 | 1456篇 |
1986年 | 1536篇 |
1985年 | 1449篇 |
1984年 | 1270篇 |
1983年 | 1063篇 |
1982年 | 748篇 |
1979年 | 1171篇 |
1978年 | 887篇 |
1977年 | 840篇 |
1976年 | 799篇 |
1975年 | 829篇 |
1974年 | 1030篇 |
1973年 | 1070篇 |
1972年 | 1018篇 |
1971年 | 951篇 |
1970年 | 927篇 |
1969年 | 899篇 |
1968年 | 754篇 |
1967年 | 844篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
161.
Kolata GB 《Science (New York, N.Y.)》1979,204(4388):44-45
162.
163.
Research and Development in Relation to Farm Animal Welfare, contributions by B. A. Baldwin, J. R. Bareham, I. J. H. Duncan, R. Ewbank, D. C. Hardwick and K. Vestergaard, Animal Management, 11, Series Edited by D. W. Fölsch. Birkhauser Verlag, Basel, 1981. ISBN‐3–7643–1241–6.
First European Symposium on Poultry Welfare. Edited by L. Yding S0RENSEN. Published by the Danish Branch of World's Poultry Science Association. 1981. 238pp. D.Kr.90. ISBN 87–88162–00–1. 相似文献
164.
Chicks monocolonized by either salmonellae or pathogenic strains of Escherichia coli had persistent and undiminished colonization of all levels of the gastrointestinal tract and frequently had bacteremia during test periods ranging to 35 days. Poults monocolonized by salmonellae or Arizona hinshawii 7:"1,7,8 developed a similar pattern of colonization. Conventionally reared chicks and poults had rather variable colonization by these pathogens, and it was most persistent in the ceca. Groups treated with a native protective microflora were infrequently colonized. Differences in colonization are explainable by lack of competing bacteria in the monocolonized group and by various degrees of protection provided by microflora colonizing the other groups. 相似文献
165.
Subsequent to a cross-sectional serological survey of Manawatu dairy farm workers, a case-control study was carried out to investigate the correlation between titres to leptospiral serovars in workers and those in cattle in their herds. A total of 52 herds was investigated, 25 of which were high risk where milkers had titres of 1:96 or greater, and 27 were case-controls where milkers had no detectable agglutinin titres at a minimum serum dilution of 1:24. The serological prevalence of titres to hardjo in cattle on high risk farms (76.5%) was significantly higher (P<0.05) than on the case-control farms (60.0%). The geometric mean titres of seropositive cattle on high risk farms were also significantly higher (P<0.01) than in the cattle from the case-control farms, especially in the younger cohorts. These findings suggest that there was active endemic hardjo infection in the two- to three-year-old cattle on the high risk farms. Titres to pomona were demonstrated in only 5.2% of the cattle from both types of farm. Workers with titres to pomona tended to be from farms on which stock, especially calves, were bought-in and pigs were kept. Conventional measures for protecting milkers from contact with infected urine appeared to be ineffective and it is concluded that prevention of leptospirosis in dairy farm workers can only be achieved by elimination of infection in the herd by vaccination of cattle. 相似文献
166.
G. Vulsteke P. Meeus 《European journal of plant pathology / European Foundation for Plant Pathology》1982,88(2):79-85
Two sprays of vinclozolin (0.5 kg a.i. ha–1) or procymidone (0.5 kg a.i. ha–1), the first at the beginning of flowering and the second two weeks later, gave the best control ofBotrytis cinerea on dwarf snap beans (Phaseolus vulgaris). Good results were also obtained with iprodione and with thiophanate-methyl. Vinclozolin and procymidone at the same program were the most active fungicides againstSclerotinia sclerotiorum. Treatments with the latter two fungicides resulted in increased yields of pods and had no influence on colour and quality of the pods. Residue levels were below the tolerances.Samenvatting Twee bespuitingen met vinchlozolin (0,5 kg a.i. ha–1) of procymidon (0,5 kg a.i. ha–1), de eerste in het stadium begin bloei en de tweede 14 dagen later tijdens de peulzetting, waren voldoende omB. cinerea in stamslabonen te bestrijden. Tevens werden goede resultaten verkregen met iprodion en thiofanaat-methyl. Vinchlozolin en procymidon gaven volgens hetzelfde schema toegepast ook de beste werking tegenS. sclerotiorum. Toepassingen van deze laatste twee fungiciden leverden een hogere peulopbrengst en hadden geen invloed op de kleur en de kwaliteit van de peulen. Het residugehalte in de peulen lag beneden de toelaatbare grens.This research was subsidized by the Instituut tot Aanmoediging van het Wetenschappelijk Onderzoek in Nijverheid en Landbouw (IWONL). 相似文献
167.
Kolata G 《Science (New York, N.Y.)》1982,217(4566):1233-1234
168.
Kolata G 《Science (New York, N.Y.)》1982,217(4564):1016
169.
Kolata G 《Science (New York, N.Y.)》1982,216(4553):1392
170.
Linvill JG 《Science (New York, N.Y.)》1982,215(4534):802-806
Realization of the potential of computer electronics for enhanced human productivity and economic impact depends strongly on the university. New manpower and continuing education for the existing work force as well as new ideas for research and development will come from that sector. University-industry coupling offers mutual advantages to the partners and benefits to the nation in the computer age. 相似文献