首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   182篇
  免费   11篇
  国内免费   15篇
  208篇
  2024年   2篇
  2023年   4篇
  2022年   7篇
  2021年   3篇
  2020年   4篇
  2019年   7篇
  2018年   5篇
  2017年   6篇
  2016年   8篇
  2015年   11篇
  2014年   3篇
  2013年   13篇
  2012年   9篇
  2011年   17篇
  2010年   10篇
  2009年   17篇
  2008年   12篇
  2007年   6篇
  2006年   12篇
  2005年   10篇
  2004年   7篇
  2003年   5篇
  2002年   1篇
  2001年   3篇
  2000年   4篇
  1999年   4篇
  1998年   2篇
  1997年   3篇
  1996年   1篇
  1995年   1篇
  1992年   2篇
  1990年   1篇
  1989年   1篇
  1988年   1篇
  1986年   2篇
  1985年   1篇
  1982年   1篇
  1980年   1篇
  1978年   1篇
排序方式: 共有208条查询结果,搜索用时 0 毫秒
101.
There is a commitment by the European pig sector to ban surgical castration of male piglets in the European Union in 2018. One alternative to castration is to raise entire male pigs, with an increased risk of boar taint. A field study was performed to: (1) evaluate inter- and intra-farm variation in boar taint prevalence, (2) investigate factors measured at slaughter influencing boar taint and (3) evaluate the relationship between sensorial scoring by a trained panel and the concentration of boar taint components. From 34 farms, neck fat samples were collected from all entire male pigs in at least two slaughter batches per farm (78 batches; 9167 animals). In addition to olfactory boar taint analysis, data were also collected on fresh skin lesions (score 0 to 3) at the slaughter line, slaughter weight, lean meat percentage, duration of transport, time spent in lairage, total delivery duration, day length, shortening of days and outdoor mean temperature. Using the hot iron method, neck fat samples were scored (eight-point scale) for boar taint. Average boar taint prevalence (score ≥3) was 5.6±2.5% and the mean difference between the maximum and minimum prevalence per farm was 4.3±3.2%. Androstenone (AND), skatole (SKA) and indole concentrations were measured for a subset (n=254) of the samples. According to binomial univariate mixed models, entire male pigs with a higher skin lesion score had higher odds of having boar taint (P=0.031), as did fatter entire male pigs (P<0.001). In the binomial multivariate mixed model lean meat percentage (P<0.001) and outdoor mean temperature (P=0.005) remained as only significant factors. Based on our results, we can conclude that these statistically significant at least partially influence the prevalence of boar taint. According to the binomial univariate mixed models SKA concentration in liquid fat seems a better predictor for boar taint than AND. There were no significant synergetic effects between boar taint compounds.  相似文献   
102.
Wild pigs, including wild boar (Sus scrofa) and feral domestic pig (Sus scrofa domestica), are associated with negative impacts in their native and introduced ranges. We compiled wild pig occurrence reports and utilized Maximum Entropy modelling to predict their potential distribution in ecoregions overlaying Argentina, Brazil, Bolivia, Chile, Uruguay and Paraguay. An analysis of their observed and potential distributions was carried out in relation to four biodiversity hotspots and 3766 protected areas to estimate the number of units and percent area currently and potentially invaded. Among biodiversity hotspots, Atlantic Forest, Cerrado, and Chilean Winter Rainfall-Valdivian Forests included 44.7% of wild pig records. The proportion of suitable area was 85% in Atlantic Forest, 61.3% in Cerrado, 37.5% in Chilean Winter Rainfall-Valdivian Forests, and 5.6% in Tropical Andes. The number of protected areas with known wild pig presence was led by Uruguay (100%), followed by Chile (20.3%), Argentina (15.8%), Paraguay (9.5%), Bolivia (6.5%), and Brazil (4.7%). The proportion of protected areas with predicted wild pig presence was highest in Uruguay (100%), followed by Paraguay (72.6%), Brazil (58.0%), Argentina (57.4%), Chile (42.2%), and Bolivia (35.9%). Our work represents the first assessment of wild pig potential distribution in South America and highlights the potentially devastating impacts of wild pigs on the regional biodiversity and national conservation targets, especially at mega-diverse areas. We present a dynamic web application that can be readily consulted by scientists, managers and decision makers to improve wild pig control and risk mitigation actions in the study region.  相似文献   
103.
104.
A practical and reliable staining procedure was developed to distinguish the viability and acrosomal status of bull, boar and rabbit spermatozoa. The first stain with trypan blue or Congo red is rapid and avoids artifacts. This stain is precipitated by neutral red during the 2 min required for fixation. The precipitate gives a high contrast black color, resistant to the subsequent rinsings and persists during the time required for staining the acrosome with Giemsa. Ten classes of spermatozoa are distinguished (live or dead with intact acrosomes, loose acrosomes, damaged acrosomes, no acrosome, or with no acrosome and no postacrosomal ring). The intact acrosomes are purple, the loose acrosomes are dark lavender and the damaged acrosomes are pale lavender. The anterior part of the head of live spermatozoa with no acrosome is white or light pink and the same area of dead spermatozoa is white or pale gray. The postacrosomal ring is red. The postacrosomal area of the head of live spermatozoa is white or light pink and the same part of dead spermatozoa is black, dark violet or gray. The procedure did not give satisfactory results for stallion spermatozoa.  相似文献   
105.
Iberian pigs and wild boars are the source of highly priced meat and dry-cured products. Iberian maternal origin is mandatory for labeled Iberian products, making necessary the authentication of their maternal breed origin. Discrimination between wild and domestic pig maternal origin may be useful to distinguish labeled wild boar meat obtained from hunting or farming. In order to detect useful polymorphisms to trace Iberian, Duroc and wild boar maternal lineages, we herein investigated the complete porcine mitochondrial DNA (mtDNA) using three complementary approaches. Near-complete mtDNA sequences (16989 bp), excluding the minisatellite present in the displacement loop region (D-loop), were successfully determined in six Iberian pigs, two Duroc and six European wild boars. To complete the mtDNA analysis, the D-loop minisatellite region was also analyzed in the same set of samples by amplification and capillary electrophoresis detection. Finally, the frequencies of Asian and European Cytochrome B (Cyt B) haplotypes were estimated in Iberian (n = 96) and Duroc (n = 125) breeds. Comparison of near-complete mtDNA sequences revealed a total of 57 substitutions and two Indels. Out of them, 32 polymorphisms were potential Iberian markers, 10 potential Duroc markers and 16 potential wild boar markers. Fourteen potential markers (five Iberian and nine Duroc), were selected to be genotyped in 96 Iberian and 91 Duroc samples. Five wild boar potential markers were selected and tested in samples of wild boars (73) and domestic pigs including: 96 Iberian, 16 Duroc, 16 Large White and 16 Landrace. Genotyping results showed three linked markers (m.7998C>T, m.9111T>C, m.14719A>G) absent in Duroc and present in Iberian pigs with a frequency 0.72. Six markers (m.8158C>T, m.8297T>C, m.9230G>A, m.11859A>G, m.13955T>C, m.16933T>C), three of them linked, were absent in Iberian pigs and present in Duroc with a joint frequency of almost 0.50. Finally three linked markers (m.7188G>A, m.9224T>C, m.15823A>G) were solely detected in wild boars with a frequency 0.22. The D-loop minisatellite results showed overlapping ranges of fragment sizes and suggested heteroplasmy, a result that nullify the use of this region for the development of breed diagnostic markers. The Cyt B haplotype results showed the presence of European haplotypes in Iberian while one of the Asian haplotypes was detected in Duroc with a frequency 0.22, linked to the Duroc marker m.9230G>A. Our results are valuable to resolve the problems of Iberian and wild boar maternal origin determination but additional markers are required to achieve totally useful genetic tests.  相似文献   
106.
小兴安岭南坡野猪家域分析   总被引:12,自引:1,他引:12  
王文  张静  马建章  刘海波 《兽类学报》2007,27(3):257-262
采用笼式活捕野猪,利用无线电遥测技术、R2V、Arcview 和SPSS 软件技术,于2004 年7 月15 日至2006年1 月19 日,对小兴安岭南坡野猪家域进行测定、计算和分析,以了解该地区野猪的家域变化规律。研究结果表明:季节变化影响野猪家域面积,在春、秋季,野猪的家域面积显著大于冬季,而春、夏季间无显著差异;不同性别及年龄野猪家域大小也不同,成体雄性秋季发情期和亚成体春季分窝期家域面积显著增加;在冬、春季家族群野猪的家域面积显著大于独体野猪家域面积,说明家族群对家域面积有影响;亚成体家域大小主要受家族群家域的影响,家族群野猪面积大,相应地家族野猪中亚成体家域面积也大。  相似文献   
107.
人兽冲突是生物多样性保护的重要研究主题,合理的损害补偿有助于野生动物可持续保护及管理。为探究太行山东北部区域野生动物损害及损害补偿,于2019年与2020年7—9月对区域内主要肇事野生动物(野猪Sus scrofa和狗獾Meles leucurus)进行了种群及损害调查;2021年7—8月基于访谈,对区域的损害赔偿及社区的受偿意愿进行了量化计测和分析。结果表明,太行山东北部区域的野猪(密度为(6.283±1.274)只/km2)及狗獾(密度为(4.855±1.610)只/km2)种群较大,对区域内的农业生产带来了较大损害,且肇事频率呈上升趋势;已有的防控手段效果有限,当地社区对野生动物保护支持度较高,但对肇事动物保护的态度相对消极;区域内的野生动物损害补偿已普遍施行,有效补偿了受损农户的部分经济损失,但也存在补偿覆盖不全面、补偿标准模糊及补偿数额偏低等问题。当地农户的受偿意愿((10962.60±1751.55)元/hm2)与其文化程度、损害补偿满意度和野生动物保护态度负相关,与保护政策支持度正相关。根据调研结果,建议加...  相似文献   
108.
While motorways are often assumed to influence the movement behaviour of large mammals, there are surprisingly few studies that show an influence of these linear structures on the genetic make-up of wild ungulate populations. Here, we analyse the spatial genetic structure of red deer (Cervus elaphus) and wild boars (Sus scrofa) along a stretch of motorway in the Walloon part of Belgium. Altogether, 876 red deer were genotyped at 13 microsatellite loci, and 325 wild boars at 14 loci. In the case of the red deer, different genetic clustering tools identified two genetic subpopulations whose borders matched the motorway well. Conversely, no genetic structure was identified in the case of the wild boar. Analysis of isolation-by-distance patterns of pairs of individuals on the same side and on different sides of the motorway also suggested that the road was a barrier to red deer, but not to wild boar movement. While telemetry studies seem to confirm that red deer are more affected by motorways than wild boar, the red deer sample size was also much larger than that of the wild boars. We therefore repeated the analysis of genetic structure in the red deer with randomly sub-sampled data sets of decreasing size. The power to detect the genetic structure using clustering methods decreased with decreasing sample size.  相似文献   
109.
东北亚地区野猪种群mtDNA遗传结构及系统地理发生   总被引:7,自引:0,他引:7  
研究测定了中国东北、华北及四川西部72个野猪(Susscrofa)个体线粒体控制区全序列,并结合GenBank报道的日本野猪(S.s.leucomystax)、琉球野猪(S.s.riukiuanus)72个同源区序列,分析了东北亚地区野猪线粒体DNA的变异及系统地理格局。在东北亚地区野猪的线粒体控制区共发现42个变异位点,均为转换,共定义了34个单元型。单元型之间的系统发生分析表明,东北亚地区野猪来自同一祖先。东北亚地区野猪现生种群具有显著的种群遗传结构,其中日本野猪与分布于中国东北地区的东北野猪之间亲缘关系较近;而琉球野猪则与华北野猪间亲缘关系较近,与日本野猪和东北野猪间的关系相对较远。嵌套进化枝系统地理分析(Nestedcladephylogeographicalanalysis,NCPA)表明:东北亚地区野猪由同一祖先经过长距离的迁徙而形成现生各种群(或亚种);琉球野猪应起源于大陆野猪,其种群演化可能经历了片断化事件;华北野猪呈现南部种群遗传多样性高的特点,其种群内部曾经历了一次分布区由南向北的扩张  相似文献   
110.
非洲猪瘟因其高死亡率、没有疫苗防疫、影响国际贸易而备受广泛关注。1921年首次确认非洲猪瘟疫情以来,先后在非洲、欧洲、美洲等多个国家和地区发病造成重大经济损失。野猪作为该病传播的重要生物媒介在俄罗斯等多个国家非洲猪瘟疫情散播中发挥了重要作用。充分了解全球非洲猪瘟疫情状况和野猪在俄罗斯非洲猪瘟疫情中的影响,分析我国野猪分布、疫病监测和管理现状,将为我国非洲猪瘟外来疫情防控策略制定提供参考。  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号