全文获取类型
收费全文 | 319篇 |
免费 | 20篇 |
国内免费 | 8篇 |
专业分类
林业 | 4篇 |
农学 | 5篇 |
基础科学 | 1篇 |
4篇 | |
综合类 | 51篇 |
水产渔业 | 17篇 |
畜牧兽医 | 265篇 |
出版年
2024年 | 1篇 |
2023年 | 7篇 |
2022年 | 5篇 |
2021年 | 35篇 |
2020年 | 20篇 |
2019年 | 17篇 |
2018年 | 10篇 |
2017年 | 6篇 |
2016年 | 7篇 |
2015年 | 8篇 |
2014年 | 8篇 |
2013年 | 17篇 |
2012年 | 27篇 |
2011年 | 16篇 |
2010年 | 8篇 |
2009年 | 12篇 |
2008年 | 10篇 |
2007年 | 15篇 |
2006年 | 14篇 |
2005年 | 15篇 |
2004年 | 12篇 |
2003年 | 13篇 |
2002年 | 8篇 |
2001年 | 7篇 |
2000年 | 7篇 |
1999年 | 7篇 |
1998年 | 2篇 |
1997年 | 3篇 |
1996年 | 2篇 |
1995年 | 3篇 |
1994年 | 3篇 |
1993年 | 3篇 |
1992年 | 3篇 |
1991年 | 3篇 |
1990年 | 5篇 |
1989年 | 3篇 |
1988年 | 1篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1980年 | 1篇 |
排序方式: 共有347条查询结果,搜索用时 0 毫秒
81.
This paper describes a study on the oestrous and ovarian activity and responses to prostaglandin F2 (PGF2) administration and artificial insemination in zebu heifers.Four cycling heifers were artificially infected with 5×106 Trypanosoma vivax organisms. Two heifers served as controls. Two injections of PGF2 were given 11 days apart, commencing at the peak of parasitaemia in the infected animals, followed by artificial insemination 72 and 96 h after the second administration of PGF2. Sera were analysed for progesterone by radioimmunoassay, while ovarian activity and oestrus were determined by rectal palpation and visual observation, respectively. All the infected heifers developed the clinical disease. All control and infected heifers had progesterone profiles consistent with luteolysis and the occurrence of oestrus following the second administration of PGF2. Progesterone levels did not return to normal luteal values in infected animals, however, whilst they did so in control animals. No control or infected heifers became pregnant.The findings suggest that PGF2 will induce a non- fertile oestrus in zebu heifers acutely infected with T. vivax. Re-ovulation is also inhibited within 22 days in a majority of infected animals. 相似文献
82.
奶牛性控冻精人工授精影响因素研究 总被引:2,自引:0,他引:2
用分离X和Y精子的性控精液进行人工授精是控制家畜性别之最简单可行的方法.然而,低密度性控精液输精效果还不如常规人工授精,许多技术环节都有待改进.以常规冻精和稀释常规冻精为对照,研究解冻方法、输精时间和部位、不同精液来源和输精员以及育成和经产牛等因素对性控冻精人工授精妊娠率的影响.结果显示,精液解冻水浴温度和持续时间对人工授精效果有显著影响,性控精液对解冻水浴温度更敏感;性控冻精和稀释常规冻精比常规冻精对输精时间要求更严格;3种精液输精到排卵卵泡同侧子宫角基部受胎率都显著高于输精于子宫体和同侧子宫角前端;3种精液育成牛受胎率(80%)都显著高于经产牛(50%);于输精同时注射促排卵素3号明显提高性控冻精受胎率;经严格挑选、能够从事胚胎移植操作的技术熟练输精员之间性控冻精受胎率差异不显著;在所设计的不同条件下,性控冻精与稀释同样倍数的常规冻精行为相似,说明精子分离过程没有对精子造成特殊损伤.研究结果说明,精确控制人工授精各个技术环节可以实现消除性控与非性控、低密度与高密度精演之间的差别,获得高妊娠率. 相似文献
83.
本试验在国标NY/636-2002母猪输精操作程序的基础上采用综合输精措施来辅助人工授精,结果显示:采用综合输精措施后,初产母猪的情期受胎率可达85.71%和86.32%(综合86.23%),经产母猪可达86.67%和86.96%(综合86.88%),两者间差异不显著,不同品种间的差异也不显著;黑猪产仔数为8.53±1.63,与约克猪产仔数(11.08±0.41)间的差异极显著,但约克猪经产和初产母猪本品种内的差异不显著。本试验说明采用综合输精措施能够有效提高母猪的繁殖性能,尤其是初产母猪的情期受胎率。 相似文献
84.
[目的]探讨半番鸭生产中的人工授精技术。[方法]选用公番鸭和樱桃谷母鸭为试验材料,采用按摩采精法和翻肛输精法进行人工授精试验,探讨输精量、输精间隔时间、输精时间以及稀释液对受精率的影响。[结果]公番鸭和樱桃谷母鸭自然交配受精率很低,平均受精率为39.58%,人工授精受精率可达74.79%。用磷酸缓冲液和Lake’s液稀释精液的受精率比较高,分别为75.24%和75.16%,与原精液组受精率(74.10%)差异不显著。精液稀释后在5℃保存24h后输精,其受精率均较低,分别为23.76%和34.33%。[结论]在半番鸭生产中,采用人工授精技术可降低精液使用量和提高受精率。 相似文献
85.
Klaus-Peter BRüSSOW Istvan EGERSZEGI Jozsef RáTKY 《The Journal of reproduction and development》2014,60(5):395-398
The uterotubal junction (UTJ) and caudal isthmus are recognized as a functional pre-ovulatory sperm reservoir (SR).
Spermatozoa are released from the SR in a complex and concerted action. However, whether this functionality is restricted
only to the ovulatory period is still open to debate. Our study was aimed to analyze the presence of spermatozoa within the
UTJ (SR), isthmus (ISTH) and ampulla (AMP) after laparoscopic intrauterine insemination (LIUI) either in the peri- (PERI) or
post-ovulatory (POST) period or at mid cycle (MID). Each uterine horn of estrus synchronized gilts (n=12) was inseminated
with 20 ml sperm (29.5×106 cells/ml). Oviducts were recovered 7 h after LIUI and separated into the UTJ, ISTH and
AMP, and sections were flushed with 10 ml PBS+EDTA solution. After centrifugation, the sperm pellet was evaluated by Čeřovský
staining. The median sperm numbers in the PERI, POST and MID groups were 578, 171 and 789 in the UTJ; 545, 233 and 713 in the
ISTH; and 496, 280 and 926 in the AMP, respectively, and there were differences between the POST and MID groups (P<0.05)
but not between the oviductal sections of each group (P>0.05). Compared with the MID group, the percent of intact sperm
cells was higher (P<0.01) in the PERI and POST groups (32.8 vs. 66.4 and 76.8%). Also,
the percentages of aberrations in the acrosome and tail were higher (P<0.05) in the MID group. Based on this, it can be
assumed that the sperm reservoir is active during different phases of the estrus cycle. However, the mid-cycle oviduct
environment considerably impairs sperm cell quality. 相似文献
86.
从激素生理调控机制说明和理解母猪发情行为变化.抓住头次静立,确定输精时间是人工授精成功的关键. 相似文献
87.
Effect of body condition score and reuse of progesterone‐releasing intravaginal devices on conception rate following timed artificial insemination in Nelore cows 下载免费PDF全文
LL Pereira AP Ferreira WG Vale LR Serique KAL Neves AC Morini BM Monteiro AHH Minervino 《Reproduction in domestic animals》2018,53(3):624-628
This study had the aim of investigating the efficiency of timed artificial insemination (TAI) through the progesterone‐releasing intravaginal device (PRID), used in new condition and for the second and third times in Nelore cows. The effects of device reuse and body condition score (BCS) on the conception rate (CR) were evaluated in 1,122 multiparous Nelore cows (mean BCS of 2.7 ± 0.4), which were randomly distributed into three groups that received new (n = 330), once (n = 439) and twice used (n = 353) PRID. Among the 1,122 females that underwent TAI, 573 became pregnant, thus representing an overall CR of 51.06%. Cows with BCS between 2.75 and 4.0 had greater (p < .0001) CR (69.75%) than cows with BSC of 2.0–2.5 (32.98%). It was observed that the CR through using PRID was 60.00%, 51.71% and 41.93% for new, once and twice used PRID, respectively, with difference between all groups (p < .0001). Under tropical conditions, animals with BCS greater than 2.5 had a higher CR, and the CR decreased proportionally with the number of times that the PRID had been used. 相似文献
88.
锯缘青蟹精子入卵过程的扫描电镜观察 总被引:5,自引:0,他引:5
利用扫描电镜详细观察了锯缘青蟹精子入卵的过程。精子以其核突起附着在卵膜上,并迅速发生顶体反应。顶体反应时,顶体囊外翻,顶体管前伸,精子核辐射臂收缩,并拖至顶体囊的后部。顶体管迅速穿过卵黄膜,携带核物质一同进入卵子。锯缘青蟹为多精着卵,数精入卵。本文同时探讨了精子顶体反应机制以及受精过程卵子的作用。 相似文献
89.
论文立足于生产实践,从技术及服务两方面分析我国猪人工授精存在的问题,就猪人工授精的重要性、人工授精站建设和人工授精技术操作规范以及目前猪人工授精上门服务存在的隐患进行了综述,以期为猪人工授精技术的规范和推广提供借鉴。 相似文献
90.
骆驼配种采用人工授精。其操作技术基本同于马、牛,采输精借用牛的假阴道和输精器。原精用12%蔗糖溶液或7%葡萄糖溶液稀释,实行阴道输精,每次输0.5毫升以上,有效精子数不低于0.8-1.0亿,受胎率达80%(42/52),产羔率75%(39/52)。驼精以蔗甘液稀释和铜纱网漂浮液氮熏蒸慢速降温法。制安瓿冻精65批665支,平均活力0.4,高者达0.5;制颗粒冻精1200余粒,活力0.3-0.5。解冻后室温(14—16℃)保存,平均存活86小时,长者达190小时。1983-1986年共输精92峰,受胎率为76.1%(70/92),产羔率为61.96%(57/92)。在第一次输精的同时,给发情母驼肌注LRH-A诱导排卵,排卵率可达94.4%。 相似文献