全文获取类型
收费全文 | 37383篇 |
免费 | 1343篇 |
国内免费 | 25篇 |
专业分类
林业 | 1782篇 |
农学 | 1119篇 |
基础科学 | 233篇 |
5474篇 | |
综合类 | 4318篇 |
农作物 | 1655篇 |
水产渔业 | 1611篇 |
畜牧兽医 | 19768篇 |
园艺 | 532篇 |
植物保护 | 2259篇 |
出版年
2020年 | 274篇 |
2019年 | 342篇 |
2018年 | 719篇 |
2017年 | 843篇 |
2016年 | 738篇 |
2015年 | 599篇 |
2014年 | 751篇 |
2013年 | 1816篇 |
2012年 | 1298篇 |
2011年 | 1410篇 |
2010年 | 912篇 |
2009年 | 836篇 |
2008年 | 1138篇 |
2007年 | 1098篇 |
2006年 | 934篇 |
2005年 | 1465篇 |
2004年 | 1366篇 |
2003年 | 1103篇 |
2002年 | 697篇 |
2001年 | 865篇 |
2000年 | 775篇 |
1999年 | 684篇 |
1998年 | 250篇 |
1995年 | 273篇 |
1992年 | 508篇 |
1991年 | 542篇 |
1990年 | 585篇 |
1989年 | 575篇 |
1988年 | 506篇 |
1987年 | 458篇 |
1986年 | 517篇 |
1985年 | 449篇 |
1984年 | 417篇 |
1983年 | 374篇 |
1982年 | 238篇 |
1979年 | 589篇 |
1978年 | 415篇 |
1977年 | 455篇 |
1976年 | 538篇 |
1975年 | 597篇 |
1974年 | 648篇 |
1973年 | 578篇 |
1972年 | 557篇 |
1971年 | 460篇 |
1970年 | 451篇 |
1969年 | 534篇 |
1968年 | 548篇 |
1967年 | 561篇 |
1966年 | 528篇 |
1965年 | 261篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
131.
J L?fstedt J A Roth R F Ross W C Wagner 《American journal of veterinary research》1983,44(7):1224-1228
In a study of susceptibilities of sows from 2 herds to experimentally induced Escherichia coli mastitis, a marked difference was seen. The "susceptible" sows were from a conventional herd and "resistant" sows were from a specific-pathogen-free herd. The purpose of the study was to determine whether deficient neutrophil function was associated with increased susceptibility to E coli-induced mastitis. Four in vitro procedures were used to evaluate polymorphonuclear leukocyte (PMN) function: (i) random migration under agarose, (ii) ingestion of 125I-iododeoxyuridine-labeled Staphylococcus aureus, (iii) quantitative nitroblue tetrazolium reduction, and (iv) iodination. After parturition and intramammary inoculation with E coli, sows from the susceptible herd were neutropenic and the neutrophils which were present in the peripheral blood had reduced function. Specifically, there were depressed random migration under agarose, S aureus ingestion, and iodination when compared with PMN function in resistant sows. These data indicate that susceptibility to E coli mastitis was associated with deficiencies in PMN numbers and function. Potential causes of the neutrophil dysfunction are discussed and include possible systemic hormonal aberrations or the presence of an inapparent viral or bacterial infection. 相似文献
132.
1. The effect of feeding the detergent, sodium lauryl sulphate at concentrations up to 10 g/kg diet on egg‐shell quality was examined in laying hens at 24, 36 and 48 weeks of age.
2. Lauryl sulphate at 2.5 g/kg or more in the diet significantly increased shell breaking strength, shell thickness and shell weight at 24 and 36 weeks. In 48‐week‐old hens only shell breaking strength was increased significantly. Egg production and egg weight were not affected significantly by lauryl sulphate.
3. Lauryl sulphate might increase these measures of quality by increasing shell deposition and/or shell elasticity. 相似文献
133.
134.
135.
In the period December 1967 through April 1969 eight spontaneous cases of pseudorabies in Danish red foxes were demonstrated by virus isolation. One fox had been kept in captivity, the remaining seven were free-living. Five of the foxes were found dead, while three, presenting abnormal behaviour when encountered, had been killed. 相似文献
136.
137.
138.
139.
140.