全文获取类型
| 收费全文 | 173445篇 |
| 免费 | 9638篇 |
| 国内免费 | 115篇 |
专业分类
| 林业 | 7186篇 |
| 农学 | 5554篇 |
| 基础科学 | 1053篇 |
| 21577篇 | |
| 综合类 | 29145篇 |
| 农作物 | 6691篇 |
| 水产渔业 | 8591篇 |
| 畜牧兽医 | 89620篇 |
| 园艺 | 2330篇 |
| 植物保护 | 11451篇 |
出版年
| 2019年 | 1670篇 |
| 2018年 | 2562篇 |
| 2017年 | 2860篇 |
| 2016年 | 2578篇 |
| 2015年 | 2217篇 |
| 2014年 | 2721篇 |
| 2013年 | 7027篇 |
| 2012年 | 5121篇 |
| 2011年 | 6300篇 |
| 2010年 | 4080篇 |
| 2009年 | 4152篇 |
| 2008年 | 6115篇 |
| 2007年 | 5790篇 |
| 2006年 | 5452篇 |
| 2005年 | 5074篇 |
| 2004年 | 4815篇 |
| 2003年 | 4965篇 |
| 2002年 | 4524篇 |
| 2001年 | 5285篇 |
| 2000年 | 5325篇 |
| 1999年 | 4266篇 |
| 1998年 | 1892篇 |
| 1997年 | 1793篇 |
| 1996年 | 1670篇 |
| 1995年 | 1968篇 |
| 1994年 | 1779篇 |
| 1993年 | 1635篇 |
| 1992年 | 3426篇 |
| 1991年 | 3622篇 |
| 1990年 | 3472篇 |
| 1989年 | 3460篇 |
| 1988年 | 3164篇 |
| 1987年 | 3155篇 |
| 1986年 | 3254篇 |
| 1985年 | 3192篇 |
| 1984年 | 2595篇 |
| 1983年 | 2326篇 |
| 1982年 | 1574篇 |
| 1979年 | 2411篇 |
| 1978年 | 1950篇 |
| 1977年 | 1686篇 |
| 1976年 | 1740篇 |
| 1975年 | 1810篇 |
| 1974年 | 2158篇 |
| 1973年 | 2132篇 |
| 1972年 | 2013篇 |
| 1971年 | 1859篇 |
| 1970年 | 1833篇 |
| 1969年 | 1838篇 |
| 1967年 | 1630篇 |
排序方式： 共有10000条查询结果，搜索用时 15 毫秒
71.
Thirteen mixed-breed beef bulls, 1 to 4 years old, were used to determine the effect of live and dead filarial nematodes, Setaria labiatopapillosa, placed in the vaginal cavity of the testes. When dead worms were used, granulomatous lesions developed on the tunica vaginalis parietalis in 7 of 8 testes. The lesions were similar to those seen in some clinical cases of periorchitis. Similar lesions developed in 5 of 6 testes after live worms were implanted in the vaginal cavity of the testes and tetramisole (8 mg/kg) was injected subcutaneously 6 days after implantation. When live worms were implanted and tetramisole was not given, lesions developed in 3 of 6 testes. It was concluded that the granulomatous reaction was a local response to dead or killed S labiatopapillosa. 相似文献
72.
Asymmetric illumination contrast: a method of image formation for video light microscopy 总被引：4，自引：0，他引：4
B Kachar 《Science (New York, N.Y.)》1985,227(4688):766-768
Images with high resolution and exceptionally broad gray scale can be obtained by the application of video contrast enhancement to an optimized procedure for imaging transparent objects with oblique rays of illumination. This technique is simple to set up. A conventional microscope with a light source whose position can be adjusted and a video camera with controls for gain and black level are the only essential components. Features such as high resolution, optical sectioning, control of contrast, and operation under low light intensity make this technique preferable, in several instances, to currently used video microscopy techniques. 相似文献
73.
Washed and unwashed red blood cells (RBC) from young calves, adult cattle, hamsters and humans were incubated with Leptospira interrogans serovars pomona and ballum. Washed cells suspended in saline were always haemolysed while unwashed cells and those which were washed and resuspended in plasma were never haemolysed, despite the presence of large numbers of organisms within the culture supernatant. Pomona produced greater haemolysis of cattle and human RBC than did ballum, but with hamster RBC ballum produced greater haemolysis than did pomona. A group of 6- to 9-month-old cattle infected with pomona showed no signs of clinical disease and RBC taken from them before infection and during the development of antibodies to pomona were haemolysed by pomona only after the cells were washed. Plasma therefore appears to have a protective function. This in vitro protective function of plasma even extended to plasma from young seronegative calves. 相似文献
74.
75.
76.
77.
78.
79.
80.