全文获取类型
收费全文 | 109358篇 |
免费 | 6123篇 |
国内免费 | 371篇 |
专业分类
林业 | 4522篇 |
农学 | 3261篇 |
基础科学 | 746篇 |
13020篇 | |
综合类 | 19937篇 |
农作物 | 4350篇 |
水产渔业 | 4928篇 |
畜牧兽医 | 57191篇 |
园艺 | 1237篇 |
植物保护 | 6660篇 |
出版年
2019年 | 1098篇 |
2018年 | 1703篇 |
2017年 | 1845篇 |
2016年 | 1652篇 |
2015年 | 1394篇 |
2014年 | 1813篇 |
2013年 | 4171篇 |
2012年 | 3134篇 |
2011年 | 3765篇 |
2010年 | 2466篇 |
2009年 | 2574篇 |
2008年 | 3765篇 |
2007年 | 3403篇 |
2006年 | 3247篇 |
2005年 | 2958篇 |
2004年 | 2875篇 |
2003年 | 2911篇 |
2002年 | 2633篇 |
2001年 | 3327篇 |
2000年 | 3367篇 |
1999年 | 2554篇 |
1998年 | 1059篇 |
1997年 | 1049篇 |
1996年 | 996篇 |
1995年 | 1138篇 |
1993年 | 971篇 |
1992年 | 2072篇 |
1991年 | 2386篇 |
1990年 | 2209篇 |
1989年 | 2220篇 |
1988年 | 1995篇 |
1987年 | 2044篇 |
1986年 | 2124篇 |
1985年 | 2020篇 |
1984年 | 1574篇 |
1983年 | 1397篇 |
1979年 | 1629篇 |
1978年 | 1266篇 |
1977年 | 1062篇 |
1976年 | 979篇 |
1975年 | 1107篇 |
1974年 | 1406篇 |
1973年 | 1423篇 |
1972年 | 1408篇 |
1971年 | 1269篇 |
1970年 | 1296篇 |
1969年 | 1231篇 |
1968年 | 1115篇 |
1967年 | 1118篇 |
1966年 | 1012篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
971.
van Bronswijk JE 《The Veterinary quarterly》1980,2(4):220-233
Summary Information published between 1567 and 1978 on this subject contains at least 223 titles. They cover medical and veterinary as well as biological aspects. Full bibliographical details of the publications are given. A subject index (to tick species, host species, and diseases transmitted) increases the availability of the data included. Some of the more interesting results of the study are discussed in a short introduction. 相似文献
972.
The optimum conditions for handling and storage of canine sera for total hemolytic complement assays were assessed. Sera from 113 normal dogs and 217 clinical admissions to the University of Pennsylvania Veterinary Hospital were assayed for total hemolytic complement levels. Normal sera had a mean value of 185 CH50 units. Sera from animals with systemic lupus erythematosus and hemorrhagic gastroenteritis, had significantly lower mean levels of complement than the normal group. Sera from dogs with generalized demodectic mange, tumors, various inflammatory diseases, hypothyroidism, seborrhea, and rheumatoid arthritis had values significantly higher than the normal population. 相似文献
973.
Brownlie J Nuttall PA Stott EJ Taylor G Thomas LH 《Veterinary immunology and immunopathology》1980,1(4):371-378
Certain immunological responses of 4-6 month old calves experimentally inoculated with either cytopathic or non-cytopathic bovine virus diarrhoea virus (BVDV) were compared with those of uninfected control calves. The tests used to demonstrate the immunological responses were the transformation of lymphocytes by PHA mitogen, the percentage of lymphocytes with surface immunoglobulin, and the antibody titres induced by an intravenous inoculation of killed Brucella abortus. There were no significant differences between the two groups of calves and therefore, the mild experimental disease produced by BVDV did not appear to affect adversely the immunological response. 相似文献
974.
975.
N. Inouye F. A. Hakkaart 《European journal of plant pathology / European Foundation for Plant Pathology》1980,86(5):265-275
Apotyvirus, isolated fromVallota speciosa, is tentatively designatedVallota mosaic virus (VMV). VMV was easily transmissible in sap and could be transferred byMyzus persicae in a nonpersistent manner. Infection was symptomless inNicotiana clevelandii andSpinacia oleracea, whereasHyoscyamus niger, chenopodium quinoa, C. amaranticolor, Tetragonia expansa andGomphrena globosa reacted with local lesions. Dilution end-point was 104–105, thermal inactivation at c. 60°C and ageing in vitro 4–8 days. With the electron microscope elongate particles with a normal length of about 750 nm could be detected in crude sap. In ultrathin sections virus particles were observed in the cytoplasm, dispersed as well as aggregated. Pinwheel and laminate aggregated inclusions were present in sectioned leaf material. The inclusions observed in negatively stained crude sap preparations exhibited fine linear striations with a periodicity of 5.3 nm. 相似文献
976.
977.
978.
Wade N 《Science (New York, N.Y.)》1978,201(4355):510
979.
980.
Marshall E 《Science (New York, N.Y.)》1978,202(4371):955-956