全文获取类型
收费全文 | 340篇 |
免费 | 20篇 |
国内免费 | 10篇 |
专业分类
林业 | 13篇 |
农学 | 31篇 |
7篇 | |
综合类 | 156篇 |
农作物 | 27篇 |
水产渔业 | 31篇 |
畜牧兽医 | 57篇 |
园艺 | 45篇 |
植物保护 | 3篇 |
出版年
2023年 | 1篇 |
2022年 | 3篇 |
2021年 | 7篇 |
2020年 | 5篇 |
2019年 | 4篇 |
2018年 | 2篇 |
2017年 | 7篇 |
2016年 | 6篇 |
2015年 | 3篇 |
2014年 | 6篇 |
2013年 | 7篇 |
2012年 | 19篇 |
2011年 | 24篇 |
2010年 | 19篇 |
2009年 | 27篇 |
2008年 | 19篇 |
2007年 | 25篇 |
2006年 | 21篇 |
2005年 | 11篇 |
2004年 | 7篇 |
2003年 | 5篇 |
2002年 | 4篇 |
2001年 | 8篇 |
2000年 | 6篇 |
1999年 | 11篇 |
1998年 | 8篇 |
1997年 | 13篇 |
1996年 | 16篇 |
1995年 | 12篇 |
1994年 | 12篇 |
1993年 | 7篇 |
1992年 | 11篇 |
1991年 | 7篇 |
1990年 | 9篇 |
1989年 | 4篇 |
1988年 | 10篇 |
1987年 | 2篇 |
1986年 | 2篇 |
排序方式: 共有370条查询结果,搜索用时 15 毫秒
1.
A four-year-old female-like Quarter Horse was admitted for clinical evaluation because of masculinized-aggressive behavior and lack of estrous signs. On external inspection, a hypertrophied clitoris and prominent muscles were observed. On gynecological examination, apparently normal mammary glands, vulva, vagina, and cervix were noted. On the other hand, the uterus had no tone and was smaller than normal. The left gonad was very soft on palpation and the right gonad was mostly firm, irregular, and wider than the left gonad. On ultrasound examination, there were no signs of regular ovarian structure or follicular activity. Because of the different shapes and consistencies of the gonads and a suspicion of increased testosterone production, a bilateral gonadectomy was recommended. Blood was collected for testosterone levels quantification and for cytogenetic and molecular investigations. After removal, gonads were analyzed macroscopically and sections were sent for histopathological examination. A final diagnosis of benign adult teratoma associated with seminiferous tubules and Leydig cells was made. On cytogenetic and molecular analyses, a normal diploid number of 64 chromosomes and the presence of the XY sex chromosomes were seen in all cells, as well as the SRY gene. Testosterone levels were higher than normal before surgery and were reduced after gonads removal. In conclusion, the masculinized behavior was probably caused by increased testosterone levels produced by testicular tissue, in a female-like horse with 64,XY SRY-positive disorder of sex development, which was associated with a teratoma. 相似文献
2.
3.
4.
薄壳山核桃及云南山核桃染色体核型分析 总被引:5,自引:0,他引:5
对胡桃科山核桃属植物薄壳山核桃和云南山核桃的染色体数目,形态进行了研究,得出了这两种折染色体核型分析结果。 相似文献
5.
福建柏变异类型的核型研究 总被引:6,自引:0,他引:6
论述了产于福建中部地区的福建柏的核型分化,四个居群的染色体数目为2n-22,但它们之间的核型组成不同,发现具园柱状树冠的变异类型具有4个随体染色体,而具宽塔状树冠的普通类型则仅具2个随体染色体,作者推测福建柏树冠和育性的变异可能与核型的改变相关,同时指出该新变异类型具有重要的观赏价值,对该新的遗传资源应加以保护和深入研究。 相似文献
6.
7.
节节麦与野燕麦8倍体杂种核型分析 总被引:1,自引:0,他引:1
节节麦(Aegilops tauschii(Coss.)Sch.2n=2x=14)与通北野燕麦(Avena fatua L.2n=6x=42)杂交,F_1自然加倍成8倍体,8倍体播成的F_2代,遗传性基本一致,PMC镜检表明,染色体数为2n=28Ⅱ。用F_2所结的种子进行根尖细胞核型分析,结果发现8倍体中包含有全套的节节麦和野燕麦的染色体。节节麦中有1对随体染色体.2对近中部着丝点染色体,4对中部着丝点染色体。野燕麦有3对随体染色体,5对近端着丝点染色体,8对近中部着丝点染色体,5对中部着丝点染色体。而节节麦与野燕麦8倍体杂种,有4对随体染色体,5对近端着丝点染色体.10对近中部着丝点染色体,9对中部着丝点染色体。核型分析结果表明,节节麦与野燕麦杂交合成的8倍体,是节节麦与野燕麦的双二倍体。 相似文献
8.
Karyotype of Canada wildrye (Elymus canadenisis L.) was described using giemsa C-banding techniques. Most of the chromosomes showed dome banding pattern polymorphism. Small to large terminal and centormere bands were observed in most of the chromosomes. A faint satellite was observed in one chromosome. Tow chromosomes had a large interstitial band near the centromeres in the long arms. The Giemsa C-banding pattern of E. Canadensis is compared to that of Pseudoroegneria spicata and Critesion boddanii to illustrate species relationship. 相似文献
9.
10.
二倍体栽培棉种草棉和亚洲棉的核型比较研究 总被引:5,自引:0,他引:5
以二倍体栽培棉种草棉(Gossypium herbaceumL.)3个品种和亚洲棉(G.arboreum L.)6个品种,以及1个亚洲棉与草棉种间杂种 F_1为材料,进行核型分析。结果表明,草棉和亚洲棉在核型上基本相似,其主要差异是草棉具有2对 st 染色体,而亚洲棉中没有;虽然2个棉种的核型类别都属于2A 型,但草棉的核型比亚洲棉更对称,属于较原始的类型。来 相似文献