全文获取类型
收费全文 | 98篇 |
免费 | 8篇 |
专业分类
林业 | 4篇 |
综合类 | 10篇 |
农作物 | 40篇 |
畜牧兽医 | 50篇 |
植物保护 | 2篇 |
出版年
2023年 | 1篇 |
2019年 | 1篇 |
2017年 | 3篇 |
2016年 | 2篇 |
2015年 | 3篇 |
2013年 | 2篇 |
2012年 | 1篇 |
2010年 | 1篇 |
2009年 | 4篇 |
2008年 | 3篇 |
2007年 | 1篇 |
2005年 | 2篇 |
2003年 | 1篇 |
2002年 | 3篇 |
1999年 | 3篇 |
1998年 | 6篇 |
1997年 | 2篇 |
1996年 | 4篇 |
1995年 | 3篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1990年 | 5篇 |
1989年 | 7篇 |
1988年 | 2篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1971年 | 1篇 |
1970年 | 4篇 |
1969年 | 1篇 |
1968年 | 1篇 |
1967年 | 4篇 |
1965年 | 4篇 |
1964年 | 1篇 |
1963年 | 3篇 |
1962年 | 2篇 |
1961年 | 3篇 |
1960年 | 5篇 |
1959年 | 4篇 |
1958年 | 1篇 |
1957年 | 6篇 |
排序方式: 共有106条查询结果,搜索用时 31 毫秒
21.
The aim of this study was to establish whether enzootic pneumonia could be induced reliably in piglets by administering an aerosolised culture of Mycoplasma hyopneumoniae. Groups of five M hyopneumoniaefree Landrace x Large White piglets weaned at 11 to 14 days of age were exposed to aerosols of in vitro cultures of a virulent strain of M hyopneumoniae. In three separate trials, 14 of 15 pigs exposed to the bacteria developed pneumonia, but pigs exposed to the culture medium alone did not develop the disease. Lung pathology, both gross and histological, indicated acute disease. Ten of the pigs were tested for seroconversion by Western blot and they were all positive. The growth rates of the infected pigs were significantly reduced and the water consumption of the infected groups was also depressed. M hyopneumoniae was recovered from eight of the 15 infected pigs. 相似文献
22.
23.
Vitrification has been the method of choice for the cryopreservation of bovine oocytes, as rapid cooling decreases chilling sensitivity. The aim of this study was to determine the in vitro and in vivo survival and the viability of immature oocytes vitrified using super‐cooled liquid nitrogen. Immature oocytes were randomly allocated to three groups: (i) non‐vitrified control group, (ii) vitrified in normal (?196°C) liquid nitrogen (LN2) and (iii) vitrified in super‐cooled LN2 (≤?200°C). Open‐pulled glass micropipettes were used as vitrification containers. Immature oocytes were in vitro‐matured, fertilized and cultured to the blastocyst stage. In vitro viability was assessed by cleavage and blastocyst rates on days 2 and 7 of culture respectively. Vitrified blastocysts derived from the immature vitrified oocytes were directly transferred to synchronous recipients. The in vitro embryo development of vitrified immature oocytes was not influenced by the LN2 state. After direct transfer (one embryo per recipient) of 16 embryos obtained from immature vitrified oocytes (eight from each vitrified group), two healthy calves were born in each group. These results indicated that vitrification of immature bovine oocytes using glass micropipettes under normal or super‐cooled LN2, resulted in viable blastocysts and live calves following in vitro embryo production. 相似文献
24.
25.
26.
LFC Brito AD Barth NC Rawlings RE Wilde DH Crews Jr PS Mir JP Kastelic 《Reproduction in domestic animals》2007,42(5):502-508
The objective of the present study was to characterize changes in serum metabolic hormones concentrations from 20 weeks before to 20 weeks post-puberty in bulls and to investigate the associations of metabolic hormones concentrations with testicular development. Leptin concentrations increased from 16 weeks before puberty to 8 weeks post-puberty and insulin concentrations increased from puberty to 8 weeks post-puberty. Growth hormone concentrations decreased after 4 weeks post-puberty, whereas IGF-I concentrations increased from 8 weeks before puberty to 8 weeks post-puberty. During this period, testicular growth was accelerated and testosterone secretion increased substantially, without any significant changes in gonadotropin secretion. Monthly circulating concentrations of leptin, IGF-I and insulin accounted for 63% of the variation in scrotal circumference and 59% of the variation in paired testes volume. In conclusion, the secretion of metabolic hormones was not associated with changes in gonadotropins concentrations. Furthermore, the associations of leptin, IGF-I and insulin concentrations with testes size indicated that these hormones might be involved in a gonadotropin-independent mechanism regulating the testicular development in peripubertal bulls. 相似文献
27.
28.
29.
Czaja A. Th. 《Journal of pest science》1970,43(11):176
Ohne Zusammenfassung 相似文献
30.