全文获取类型
收费全文 | 10795篇 |
免费 | 525篇 |
国内免费 | 839篇 |
专业分类
林业 | 1832篇 |
农学 | 714篇 |
基础科学 | 1088篇 |
970篇 | |
综合类 | 4282篇 |
农作物 | 430篇 |
水产渔业 | 276篇 |
畜牧兽医 | 1876篇 |
园艺 | 320篇 |
植物保护 | 371篇 |
出版年
2024年 | 69篇 |
2023年 | 196篇 |
2022年 | 336篇 |
2021年 | 360篇 |
2020年 | 346篇 |
2019年 | 448篇 |
2018年 | 243篇 |
2017年 | 413篇 |
2016年 | 549篇 |
2015年 | 434篇 |
2014年 | 669篇 |
2013年 | 584篇 |
2012年 | 1014篇 |
2011年 | 798篇 |
2010年 | 640篇 |
2009年 | 593篇 |
2008年 | 502篇 |
2007年 | 551篇 |
2006年 | 483篇 |
2005年 | 339篇 |
2004年 | 321篇 |
2003年 | 246篇 |
2002年 | 202篇 |
2001年 | 225篇 |
2000年 | 186篇 |
1999年 | 171篇 |
1998年 | 165篇 |
1997年 | 136篇 |
1996年 | 119篇 |
1995年 | 125篇 |
1994年 | 129篇 |
1993年 | 95篇 |
1992年 | 88篇 |
1991年 | 93篇 |
1990年 | 68篇 |
1989年 | 64篇 |
1988年 | 60篇 |
1987年 | 30篇 |
1986年 | 15篇 |
1985年 | 8篇 |
1984年 | 12篇 |
1983年 | 3篇 |
1982年 | 4篇 |
1981年 | 4篇 |
1980年 | 4篇 |
1979年 | 5篇 |
1978年 | 3篇 |
1977年 | 6篇 |
1973年 | 2篇 |
1956年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
61.
Takeyuki OZAWA Ruriko TAKADA Jiro NISHITANI Masaru FUJITA Hugh T. BLAIR 《Animal Science Journal》2010,81(2):271-275
A sensory survey was carried out using 4 different types of whole goat milk among middle‐class females to investigate consumer acceptability of goat milk and whether there is an opportunity to expand the sale of goat milk products in Japan. Four different types of whole milk powder (domestic concentrate‐fed, domestic pasture‐fed, USA commercially canned, and New Zealand commercially canned) were used. Fresh cow milk was served as a control. Thirty‐one housewives evaluated the 5 liquid milk samples for smell, taste and overall characteristics on a scale of 1 (low) to 3 (high). Chi‐square analyses were carried out to detect significant differences between the milk types in each category. The goat milk from the USA was the most preferred goat milk with respect to smell and overall evaluation. Domestic pasture‐fed milk received the lowest grade in the evaluation for its ‘grassy and goaty’ smell. This result shows us that pasture intake affects the taste and smell of powdered milk which gives the lowest evaluation by the participants. If Japanese goat milk producers want to be successful in the domestic goat milk market and compete against goat milk products from other countries, they should improve production methods and flavor of their products. 相似文献
62.
为了探索特异性免疫学诊断方法对鸡骨型白血病(OP)的检测效果。用双盲法分批采样同时进行羽髓琼脂扩散试验和胫骨X线摄片检查对比,共检834只鸡(433羽属天然自发OP鸡群,401羽属人工诱发实验鸡群)。结果羽髓琼扩试验的OP阳性检出率为3.48%(29/834:)。阳性病理符合率为75.86%(22/29)。阳性误诊(假阳性)率24.13%(7/29),阴性误诊(假阴性)率36.15%(291/805)。而X线摄片检查的OP阳性检出率为38.37%(320/834)。X线阳性完全可获病理组织学证实,不存在假阳性或假阴性。把禽白血病羽髓琼扩试验试用于检测鸡骨型白血病尚属初次报道,其阳性检出率低而误诊率高,尚不宜作OP检测手段。放射摄片诊断的阳性检出率高而误诊率低,可快速诊断,故适用于OP检疫。 相似文献
63.
Objective Guinea pigs have a very low threshold of corneal sensitivity and at the same time nearly no reflex tearing compared to dogs, cats, and horses. The question arose whether there is a general correlation between corneal sensitivity and the quantity of reflex tearing. Animals studied Totally 160 animals of 8 different species (20 animals per species) were investigated. Procedures The corneal touch threshold (CTT) was measured with a Cochet–Bonnet esthesiometer. The palpebral fissure length (PFL) was measured with a calliper ruler. The Schirmer tear test (STT) was modified by adapting the width of the STT strip to the PFL of every species. For the STT II, 0.4% oxybuprocaine was applied. Results Corneal touch threshold: Cows (1.67 g/mm2), horses (1.23 g/mm2), sheep (1.13 g/mm2), goats (1.44 g/mm2), dogs (2.16 g/mm2), and cats (1.33 g/mm2) show similar CTT values. In contrast, rabbits (6.21 g/mm2) and guinea pigs (7.75 g/mm2) show a significantly lower CTT. Tear Production Difference STT I ? STT II: Rabbits have the greatest decline in tear production with 38.4%, followed by sheep (33.3%), dogs (31.1%), cats (24.7%), cows (23.7%), horses (18.0%), and goats (14.0%). Guinea pigs have no decline, but a slight increase of ?16.0%. Correlation CTT and STT II ? STT I Difference: Pearson’s correlation coefficient shows a small, but significant correlation. The coefficient of determination can only forecast a value with 7.1% certainty. Conclusions The high variance and low reproducibility of results suggest that the measuring devices are inappropriate to assess the evaluated parameters. Therefore, no assured correlation between the corneal sensitivity and the quantity of reflex tearing could be found. 相似文献
64.
苜蓿种带真菌及其致病性测定 总被引:21,自引:0,他引:21
对来自我国新疆,内蒙古,吉林,陕西,甘肃,宁夏,山东,黑龙江,山西,河北和江苏等11个省(自治区)苜蓿产区的30个审定登记品种的38个苜蓿种子样品进行了系统的种带真菌检测研究;测定了21种25个真菌分离物对苜蓿幼苗根组织的入侵性及19种真菌对苜蓿种子萌发和幼苗生长的影响。 相似文献
65.
对呼伦贝尔黄花苜蓿进行区域试验研究结果表明:呼伦贝尔黄花苜蓿在各试验点种植均表现出较强的适应性,鲜草和千草产量与对照品种肇东苜蓿接近,3个试验点3年平均鲜草产量为33865.6kg/hm^2,干草产量为9146.2kg/hm^2,分别比对照的肇东苜蓿低0.6%和3.2%。方差分析表明二者无显著差异,具有良好的丰产性和持久性,对呼伦贝尔高寒地区严酷的自然条件具有很强的适应性,适宜在我国北方高寒地区大面积推广种植。 相似文献
66.
This paper presents a stochastic simulation model to evaluate the efficacy of regional or national surveys aimed at identifying infection in populations of animals. The process of evaluation involves specification or calculation of cluster-level test sensitivity and specificity, which are derived from two probability distributions of the number of individual-level positive tests expected from non-infected and infected clusters, respectively. Probability distributions for the number of positive clusters expected in a situation of freedom from infection and under various levels of cluster prevalence are specified and used to determine survey properties (the survey being considered a diagnostic system), and ROC curves are drawn. Likelihood ratios allow investigators to state the extent to which a survey result is more likely to be observed if the region or country is infected at a given prevalence than if it is free from infection. The result of a survey carried out to investigate the presence of porcine reproductive and respiratory syndrome (PRRS) in Switzerland is used to illustrate this approach. The model can be adapted to a wide range of survey designs. 相似文献
67.
Dominique Hazard Tiphaine Macé Amandine Kempeneers Eric Delval Didier Foulquié Jacques Bouix Alain Boissy 《Zeitschrift für Tierzüchtung und Züchtungsbiologie》2020,137(4):374-383
In livestock, improving maternal reactivity towards the litter is an important issue in breeding strategies to promote production and animal welfare. As of yet, no studies have investigated the within-breed genetic variation of maternal reactivity in sheep. The objective of this study was to estimate the genetic parameters of maternal reactivity traits. A total of 1,095 primiparous and 1,441 multiparous Romane ewes were phenotyped 24 hr postlambing using a behavioural test (arena test, AT) over a 10-year experimental period. The test consisted of three successive phases evaluating the ewe's attraction to her litter, reactivity to separation from her litter, and reactivity to a conflict between attraction to her litter and avoidance of a motionless human. The ewes were reared exclusively on rangelands (South of France) and lambed outdoors in the spring. High-pitched bleating and low-pitched bleating in the AT were mostly highly heritable (0.39‒0.46). Heritabilities were moderate for proximity to the litter in the presence of a human (0.27) and low for locomotion and vigilance in the AT (0.09‒0.15). The measurements of a given behaviour in the three phases of the AT were highly genetically correlated. Few genetic correlations were found between the different behavioural traits in the AT, the highest correlations being between high-pitched bleating and low-pitched bleating (−0.43 to −0.77). In conclusion, our findings demonstrate moderate-to-high heritability for maternal reactivity traits. These traits could be included in genetic selection schemes to enhance maternal attachment provided there is no unfavourable link with other production traits. 相似文献
68.
69.
猪链球菌2型四川分离株猪体回归试验 总被引:5,自引:3,他引:5
选用35~38日龄的健康断奶仔猪21头,分3组,用2005四川分离株SSsc0501分别经静脉、肌肉注射和口服3种途径感染,进行猪体回归试验。肌肉注射组(含菌0.6×108个/mL)16 h开始出现症状,至36 h全部死亡,发病率、病死率均为100%;静脉注射组(含菌0.2×108个/mL)25 h开始出现症状,48 h内全部死亡,发病率和病死率均为100%;口服攻毒组(含菌2×108个/mL)90 h后开始有发病症状,第9天有1头死亡,发病率75%,病死率33%。从感染病死猪的肝脏、脾脏、肾脏、心血、大脑、脑脊液、淋巴结、肺脏和关节液中均分离到链球菌,经鉴定为试验攻毒的目的菌,表明猪体能够很好地用于猪链球菌2型动物感染模型,同时说明该菌侵害器官广泛,为进一步探讨该病的综合防制提供了重要技术依据。 相似文献
70.
以国际植物新品种保护联盟(UPOV)制定的植物新品种DUS(distinctness, uniformity and stability)测试指南总则(TG/1/3)、箭筈豌豆DUS测试指南(TG/32/7)等技术文件为指导,对箭筈豌豆DUS测试指南的核心技术内容:测试性状和参照品种等开展了研究。在国内外共收集到51个箭筈豌豆品种,并进行连续2年的田间观测。观测性状总计31个,包括UPOV箭筈豌豆DUS测试指南中的23个性状,以及本实验发现有特异性的8个新增性状。对每个测试性状的表达状态、观测时期、测定方法、观测数量等进行了分级和详尽描述。共筛选出32个参照品种(国际21个, 我国11个),确定了123个表达状态。并对UPOV 箭筈豌豆DUS测试指南中“外种皮底色”和“种子形状”表达状态的分级进行了补充。本研究结果可为我国箭筈豌豆新品种 DUS 测试指南的制定奠定技术基础,对促进我国箭筈豌豆品种保护、审定和育种工作具有重要的意义。 相似文献