全文获取类型
收费全文 | 963篇 |
免费 | 6篇 |
国内免费 | 23篇 |
专业分类
林业 | 20篇 |
农学 | 49篇 |
基础科学 | 3篇 |
63篇 | |
综合类 | 392篇 |
农作物 | 44篇 |
畜牧兽医 | 385篇 |
园艺 | 7篇 |
植物保护 | 29篇 |
出版年
2023年 | 5篇 |
2018年 | 15篇 |
2016年 | 6篇 |
2015年 | 8篇 |
2014年 | 6篇 |
2013年 | 10篇 |
2012年 | 62篇 |
2011年 | 67篇 |
2010年 | 9篇 |
2009年 | 12篇 |
2008年 | 55篇 |
2007年 | 81篇 |
2006年 | 51篇 |
2005年 | 47篇 |
2004年 | 54篇 |
2003年 | 33篇 |
2002年 | 39篇 |
2001年 | 32篇 |
2000年 | 38篇 |
1999年 | 17篇 |
1997年 | 8篇 |
1995年 | 6篇 |
1994年 | 15篇 |
1993年 | 14篇 |
1992年 | 8篇 |
1991年 | 9篇 |
1990年 | 12篇 |
1989年 | 13篇 |
1986年 | 5篇 |
1985年 | 5篇 |
1984年 | 5篇 |
1982年 | 8篇 |
1981年 | 7篇 |
1979年 | 8篇 |
1958年 | 9篇 |
1956年 | 5篇 |
1955年 | 5篇 |
1953年 | 4篇 |
1941年 | 4篇 |
1940年 | 5篇 |
1935年 | 4篇 |
1934年 | 4篇 |
1930年 | 4篇 |
1924年 | 6篇 |
1922年 | 6篇 |
1921年 | 4篇 |
1920年 | 4篇 |
1913年 | 4篇 |
1909年 | 4篇 |
1888年 | 4篇 |
排序方式: 共有992条查询结果,搜索用时 179 毫秒
1.
2.
3.
Afifi EA Khalil MH Khadr AF Youssef YM 《Zeitschrift für Tierzüchtung und Züchtungsbiologie》1994,111(1-6):138-147
SUMMARY: A crossbreeding experiment was carried out in Egypt using a local breed (Baladi Red, BR) and New Zealand White (NZ) to estimate direct heterosis, maternal additive effects and direct sire effects on some growth and carcass traits in rabbits. Data of body weight (at 5, 6, 8, 10, 12 weeks) and daily gains (at intervals of 5-6, 6-8, 8-10, and 10-12 weeks) on 2153 weaned rabbits were collected. Carcass performance at 12 weeks of age (weight and percentages of carcass, giblets, head, fur, blood and viscera) on 213 male rabbits was evaluated. Estimates of coefficients of variation (CV) for most growth and carcass traits were high and ranged from 10.0 to 40.2%. Sire-breed was of considerable importance in the variation of growth traits and some carcass traits, while dam-breed contributed little. Sire-breed × dam-breed interaction affected (P<0.01 or P<0.001) most body weights and gains studied, while it contributed little to the variation of carcass traits. The purebred NZ resulted in rabbits with heavier weights and carcass and with lighter non-edible carcass (blood and viscera) compared to the BR. Heterosis percentages for most growth traits were significant and ranged from 2.5% to 5.0% for body weights and from 0.7% to 9.5% for daily gains. Insignificant positive direct heterosis was observed for most carcass traits. Crossbred rabbits from NZ sires with BR dams were superior to from the reciprocals. Maternal-breed effects on most weights and gains were insignificant, while sire-breed contrasts for some weights and gains proved significant. Postweaning growth and carcass performances of BR-mothered rabbits generally surpassed the NZ mothered, while NZ-sired rabbits were superior at later ages. High edible carcass was observed for BR-sired rabbits, while more non-edible carcass wastes (blood and viscera) for NZ-sired rabbits. Maternal-breed effects appeared to be less important than paternal-breed effects in influencing most weights, gains and carcass traits studied. ZUSAMMENFASSUNG: Heterosis, maternale und direkte Wirkungen bei Wachstums- und Schlachtk?rpermerkmalen in Kaninchenkreuzungen Der Kreuzungsversuch wurde mit lokalen ?gyptischen Rassen (BR) und Neuseeland Wei?en (NZ) zur Sch?tzung direkter Heterosis, maternaler additiver Wirkungen, direkter Vater-Wirkung auf einige Wachstums- und Schlachtk?rpermerkmale von Kaninchen durchgeführt. Angaben über K?rpergewicht (5, 6, 8, 10, 12 Wochen) und Zuwachs (Intervalle 5 bis 6, 6 bis 8, 8 bis 10, 10 bis 12 Wochen) wurden von 2153 abgesetzten Kaninchen gewonnen. Die Schlachtk?rperleistungen bei 12 Wochen Alter (Gewicht und Anteil von Schlachtk?rper, Kopf, Pelz, Blut und Innereien) stammen von 213 m?nnlichen Kaninchen. Sch?tzungen der Variationskoeffizenten (CV) für meiste Wachstums- und Schlachtk?rpermerkmale waren hoch und bewegten sich zwischen 10 und 40,2%. Vaterrasse hatte erheblichen Einflu? auf Unterschiede in Wachstumsrate und einige Schlachtk?rpermerkmale, w?hrend die Mutterrasse weniger beigetragen hat. Interaktion zwischen beiden beeinflu?te die meisten K?rpergewichts- und Zuwacnsleistungen, w?hrend sie wenig zur Variabilit?t der Schlachtk?rpermerkmale beigetragen hat. Reinrassige NZ waren schwerer und hatten weniger nicht nutzbare Schlachtk?rperteile (Blut und Eingeweide) verglichen mit BR. Heterosis-Prozente für die meisten Wachstumsmerkmale waren signifikant und schwankten zwischen 2,5 und 5% für K?rpergewicht, 0,7 bis 9,5% für Zuwachs. Insignifikante positive direkte Heterosis wurde für die meisten Schlachtk?rpermerkmale beobachtet. Kreuzungskaninchen von NZ V?tern waren den reziproken überlegen. Maternale Wirkungen auf meiste Gewichtsmerkmale waren insignifikant, w?hrend Vaterrassenkontraste hierfür signifikant waren. Zuwachs- und Schlachtk?rperleistung von BR ges?ugten Kaninchen haben im allgemeinen die von NZ ges?ugten übertroffen, w?hrend von NZ B?cken gezeugte in sp?teren Altersabschnitten überlegen waren. Hohe Werte für Schlachtk?rper wurden für BR ges?ugte Kaninchen gefunden, w?hrend mehr nicht verzehrbare Abf?lle (Blut und Eingeweide) bei NZ gezeugten vorhanden war. Maternale Rassenwirkungen schienen weniger wichtig als paternale zu sein. 相似文献
4.
正猪传染性胸膜肺炎是一种危害养猪业较为严重的传染病。2017年11月份,建平县太平庄乡多家养猪大户的猪突然发病,临床表现为体温突然升高,呼吸极度困难,发病后很快死亡。经临床症状检查、剖检及实验室检验,确诊为猪传染性胸膜肺炎。现将诊疗结果报告如下,供广大养殖者参考。1病原体猪传染性胸膜肺炎病原为胸膜肺炎放线杆菌,革 相似文献
5.
6.
7.
Boden LA Anderson GA Charles JA Morgan KL Morton JM Parkin TD Clarke AF Slocombe RF 《Equine veterinary journal》2007,39(5):422-428
REASONS FOR PERFORMING STUDY: The risk of fatality is greater in jump than in flat racing in Victoria, Australia. This is the first study to identify risk factors specific to jump starts in Victoria. OBJECTIVE: To identify risk factors for fatality of Thoroughbred racehorses in jump starts on all racecourses in Victoria, Australia between 1989 and 2004. METHODS: Fatalities comprised all horses that died during or immediately after a jump (hurdle or steeplechase) race or official jump trial and all horses that were subjected to euthanasia within 24 h of an event in which an injury was sustained. The retrospective study involved 191 case starts and 2324 control starts. Univariable and multivariable backward stepwise logistic regression was used to identify risk factors for fatality at any one start. A multiple level model was used with racecourse included as a random effect. RESULTS: In the final multivariable model, the duration of the racing career of the horse, the number of flat, hurdle and steeple starts accumulated in the 60 days prior to the case or control start, the number of flat and jump starts accumulated over the racing career, if the horse had had a start between 1 and 14 days prior to the case or control start, the type of jump race (hurdle or steeple), the calendar year of the start and the location of the racecourse were associated with fatality. CONCLUSIONS: The findings highlight the need to investigate further the differences between hurdle and steeplechase events and the adverse effect of prolonged prior flat racing careers on the risk of fatality in jump starts. POTENTIAL RELEVANCE: This is the first study to examine risk factors for fatality in jump starts in Victoria. The results should shape the development of interventions to reduce the risk in jump starts in the future. 相似文献
8.
Siarkou VI Mylonakis ME Bourtzi-Hatzopoulou E Koutinas AF 《Veterinary microbiology》2007,125(3-4):304-312
The purpose of this study was to characterize, at the molecular level, the Ehrlichia canis strains involved in naturally occurring canine monocytic ehrlichiosis (CME) in Greece, and to investigate if any sequence diversity exists between the 16S rRNA genes of those involved in the mild non-myelosuppressive or the severe myelosuppressive form of CME. To this end, amplification of the ehrlichial 16S rRNA gene was attempted by nested polymerase chain reaction (PCR) assays in bone marrow (BM) aspirates from 20 dogs tentatively diagnosed as having non-myelosuppressive (n=10, group A) or myelosuppressive (n=10, group B) CME. PCR assay using E. canis-specific primers revealed that 15 BM samples, including all group A and 5 group B dogs, were positive. Using universal PCR primers, a nearly full-length 16S rRNA gene could be amplified from 13 BM samples, including 9 group A and 4 group B dogs. The 16S rDNA analysis based on secondary structure revealed that all sequences of the Greek strains were identical to each other and indicated 100% identity among some American (Venezuelan and Brazilian), European (Greek), Middle Eastern (Turkish) and Asiatic (Thailand) strains. The results of this study suggest that the E. canis strains involved in the non-myelosuppressive and myelosuppressive forms of CME in Greece share an identical 16S rRNA genotype. 相似文献
9.
Koutinas AF Saridomichelakis MN Argyroudis S Koutinas CK Karatzanos P Giadinis N 《Veterinary dermatology》2007,18(4):211-216
In a flock of 290 sheep, a total of 20 ewes (6.9%) with an age range of 1.5-4 years, developed a nonpruritic dermatitis characterized by alopecia/hypotrichosis, erythema, hyperpigmentation, crusting, superficial ulcers, exudation and thickening of the skin that was localized mainly to the peri-ocular area. Frequent and massive feeding of swarming sucking flies on the lesional sites was witnessed. In every instance (n = 6), Staphylococcus aureus was cultured from the exudate and the aseptically obtained skin biopsy samples from both recurrent and new cases. The main predisposing factor was the presence of small troughs, which forced the sheep to compete for food. Intramuscular administration of cefalexin for 7 days resulted in the resolution of lesions over a 2-week period. No further cases or recurrences were seen over the 16-month follow-up period. The main histopathological feature of this skin disease was a superficial and deep, perivascular to interstitial eosinophilic and mononuclear dermatitis. 相似文献
10.
以3个普通小麦品种为材料,用^60Coγ射线辐照小麦幼胚愈伤组织,在MR1、MR2代中才观察到广泛变异,其后代在育性、株高、抽穗期、千粒重、株型、蛋白质含量等方面者发生了明显变异,这些变异较单纯用组织培养得到的无性系的后代的变异频率更大,变异范围也更为广泛,并且从MR2中得到了几个有较高利用价值的变异株系。 相似文献