全文获取类型
收费全文 | 6809篇 |
免费 | 408篇 |
国内免费 | 45篇 |
专业分类
林业 | 552篇 |
农学 | 288篇 |
基础科学 | 79篇 |
1777篇 | |
综合类 | 282篇 |
农作物 | 415篇 |
水产渔业 | 733篇 |
畜牧兽医 | 2442篇 |
园艺 | 185篇 |
植物保护 | 509篇 |
出版年
2024年 | 11篇 |
2023年 | 40篇 |
2022年 | 96篇 |
2021年 | 158篇 |
2020年 | 154篇 |
2019年 | 191篇 |
2018年 | 246篇 |
2017年 | 251篇 |
2016年 | 245篇 |
2015年 | 201篇 |
2014年 | 265篇 |
2013年 | 422篇 |
2012年 | 482篇 |
2011年 | 526篇 |
2010年 | 319篇 |
2009年 | 315篇 |
2008年 | 434篇 |
2007年 | 405篇 |
2006年 | 349篇 |
2005年 | 300篇 |
2004年 | 299篇 |
2003年 | 273篇 |
2002年 | 203篇 |
2001年 | 163篇 |
2000年 | 161篇 |
1999年 | 154篇 |
1998年 | 50篇 |
1997年 | 42篇 |
1996年 | 37篇 |
1995年 | 42篇 |
1994年 | 22篇 |
1993年 | 20篇 |
1992年 | 30篇 |
1991年 | 21篇 |
1990年 | 22篇 |
1989年 | 25篇 |
1988年 | 19篇 |
1987年 | 19篇 |
1986年 | 17篇 |
1985年 | 23篇 |
1984年 | 14篇 |
1983年 | 18篇 |
1982年 | 9篇 |
1979年 | 18篇 |
1978年 | 15篇 |
1976年 | 9篇 |
1973年 | 13篇 |
1971年 | 9篇 |
1967年 | 8篇 |
1965年 | 8篇 |
排序方式: 共有7262条查询结果,搜索用时 15 毫秒
41.
Galán A Martín-Suárez EM Granados MM Gallardo JM Molleda JM 《Veterinary ophthalmology》2006,9(1):7-15
Fluorescein angiography without sedative or anesthetic agents was evaluated in 20 normal goats and 20 normal sheep. All of the angiographic phases were observed using 20 mg/kg fluorescein IV in both species. Fundus fluorescein angiography results revealed wide stars of Winslow in the tapetal fundus, central or marginal flow during the first part of the arterial phase, delayed filling of the focal areas in the choroid near the optic disc that often coincided with others in the disc, and lack of evidence of the 'striate area' in the tapetal fundi. In goats, the angiographic times were 6.54+/-1.25 s for the arterial phase (TA), 7.80+/-1.37 s for the arterio-venous phase (TAV), and 14.13+/-2.01 s for the venous phase (TV). I1: 1.30+/-0.30 s (time elapsing between TA and TAV), and I2: 6.20+/-1.60 s (time elapsing between TAV and TV). In sheep, times were 9.54+/-2.18 s TA, 11.73+/-2.10 s TAV, and 20.86+/-2.74 s TV. I1: 2.04+/-0.75 s and I2: 8.98+/-2.47 s, respectively. Due to the large size of the fundic vessels in sheep and goats, fluorescein angiography of the retinal vasculature can facilitate the study of the different vascular diseases in these species. 相似文献
42.
Liste G María GA Buil T García-Belenguer S Chacón G Olleta JL Sañudo C Villarroel M 《DTW. Deutsche tier?rztliche Wochenschrift》2006,113(2):59-64
The transport of domestic animals by road can increase levels of stress and decrease meat quality, especially in unfavourable climates. The purpose of this study was to investigate the effect of journey duration and vertical position on the transport truck on some physiological indicators of stress and on instrumental meat quality parameters in commercial rabbits. In the summer months (June and July, 2003), 78 rabbits were subjected to either long (7 h) (LJ) or short (1 h) (SJ) journeys (3 replicates each, n = 6) between the farm and an abattoir in northern Spain. The position (top, middle, or bottom) occupied by the rabbits on the Multi-Floor cage Rolling Stand (MFRS) of the transport truck was recorded. Blood samples were collected at sticking and meat pH was measured at 24 h post-mortem (pH24). At 48 h post-mortem, samples of the M. longissimus dorsi were used to determine water-holding capacity (WHC) and instrumental tenderness using an INSTRON machine. The levels of corticosterone, glucose, lactate, and creatine kinase were slightly higher in LJ than in SJ samples, but the difference was not statistically significant (p < or = 0.10). Independent of journey length, rabbits in the middle and bottom of the MFRS showed higher levels (p < or = 0.05) of glucose and creatine kinase (middle), and corticosterone (bottom) than the rabbits located at the top floor. The pH 24 and WHC values of the SJ and LJ rabbits did not differ significantly. Journey length had a significant effect (p < or = 0.01) on meat tenderness. The meat from rabbits subjected to LJ had higher values of maximum stress and total toughness than did the SJ rabbits (p < or = 0.05). There were similar differences (p < or = 0.05) between LJ and SJ rabbits in their stress values of compression at 20% and 40% (measures of the tenderness of raw meat). In hot weather, the position on the transport truck appeared to have a greater effect on rabbit welfare than the duration of the journey. 相似文献
43.
Ruiz-Fons F Fernández-de-Mera IG Acevedo P Höfle U Vicente J de la Fuente J Gortazár C 《Veterinary parasitology》2006,140(1-2):133-142
Commercial hunting of Spanish wild ungulates has made them an important economic resource. Wild ungulates may have an important role in the maintenance of ixodid tick populations, and also as reservoirs of pathogens. We studied the ixodid ticks that parasitize Iberian red deer and European wild boar from Spain. Ixodid ticks (n=6,336) were collected from 431 Iberian red deer and 142 wild boar in different regions of Spain. We found 10 different ixodid tick species parasitizing Iberian red deer, mainly Hyalomma marginatum marginatum (63.7%), Rhipicephalus (Boophilus) annulatus (7.9%) and R. bursa (7.5%). R. (Boophilus) annulatus was only collected in the province of Cádiz (southern Spain). We found 8 ixodid tick species on the wild boar, mainly Hy. m. marginatum (68.7%), R. bursa (14.6%) and Dermacentor marginatus (9.3%). We found one adult Hy. marginatum rufipes and one adult Hy. anatolicum excavatum parasitizing wild boar from south-central Spain. Mean prevalence of ixodid ticks was 41.3+/-0.08% (n=475) and 31+/-0.09% (n=284) and intensity of parasitization was 13.9+/-0.2 (n=283) and 13.6+/-0.3 (n=130) ticks/animal for Iberian red deer and wild boar, respectively. Only 5 of the 13 ixodid tick species found were shared by Iberian red deer and wild boar. This finding could indicate a host preference when Iberian red deer and wild boar share common habitats. In both Iberian red deer and wild boar from south-central Spain the monthly relative frequencies of Hy. m. marginatum and R. bursa presented an inverse pattern. The highest Hy. m. marginatum relative frequencies coincided with the lowest R. bursa relative frequencies along the year. R. bursa and I. ricinus were present in areas from northern to southern Spain while Hyalomma sp. and D. marginatus were exclusively collected in the two southern thirds of Spain. Haemaphysalis sp. and D. reticulatus were collected in northern Spain. Hy. m. marginatum and R. bursa were present during the whole year in red deer and wild boar from south-central Spain, showing more than one life cycle per year. These results are important for understanding the role of wild ungulates in the maintenance of tick infestations and to improve tick control programmes. 相似文献
44.
45.
Laura N Cuypers Wim L Cuypers Amélie Gildemyn-Blomme Laura Abraham Senne Aertbeliën Apia W Massawe 《African Zoology》2017,52(2):119-123
In Africa, indigenous multimammate mice (Mastomys natalensis) only appear to live commensally in houses when invasive black rats (Rattus rattus) are absent, yet little is known about the underlying mechanism. Avoidance through smell may cause the absence of M. natalensis from areas occupied by R. rattus, but this hypothesis has not yet been tested. We conducted a Y-maze choice experiment where 15 M. natalensis were offered a choice between corridors containing conspecific scent, R. rattus scent and a control scent. Residence time in the R. rattus corridor was greater than that in the control corridor but equal to that in the M. natalensis corridor, suggesting that multimammate mice do not actively avoid the scent of their invasive competitor. 相似文献
46.
del Río ML Navas J Martín AJ Gutiérrez CB Rodríguez-Barbosa JI Rodríguez Ferri EF 《Veterinary research》2006,37(1):49-59
Bacteria have evolved a set of highly specialized proteins to capture iron in iron-depleted environments. The acquisition and uptake of iron present in the extracellular milieu of eukaryotic organisms is indispensable for the growth and survival of microbial pathogens in the course of infection. Haemophilus parasuis is the causative agent of Gl?sser disease, which is responsible for considerable financial losses in pig-rearing worldwide. To gain insight into the mechanisms involved in siderophore-mediated iron uptake in H. parasuis, genes in the H. parasuis ferric hydroxamate uptake (Fhu) region were amplified in the work being reported here. As has been described in A. pleuropneumoniae, an Fhu genomic region was also present in H. parasuis, being composed of four potential consecutive open reading frames (ORF) designated as fhuC, fhuD, fhuB, and fhuA, respectively. By immunoblotting, using a cross-reactive polyclonal antibody raised against Actinobacillus pleuropneumoniae FhuA protein, it was demonstrated that this protein was constitutively expressed in H. parasuis and its level of expression was not modified under conditions of restricted iron availability. This is the first report describing the presence of the fhu genes in H. parasuis. Our results indicate that FhuA protein expression is not affected under iron-restricted conditions, however, it is one of the targets of the humoral immune response. 相似文献
47.
The aim of this study was to characterize changes in physiological and biochemical parameters during electroejaculation (EE) under general anaesthesia in adult and yearling pampas deer males (Ozotoceros bezoarticus). The relation between heart rate, pulse rate, respiratory rate and oximetry with EE voltages was studied. The changes in cortisol, alkaline phosphatase, creatine kinase, aspartate aminotransferase and rectal temperature were determined before and after electroejaculation (BEE and AEE). Heart rate and pulse rate values increased during EE, with a greater increase in heart rate in adults (p < 0.01). Respiratory rate and SpO2 were not affected by EE or category. The rectal temperature decreased in adults and yearlings during EE (p = 0.0001). Alkaline phosphatase, creatine kinase and aspartate aminotransferase concentrations increased AEE (p < 0.001, p < 0.01 and p < 0.05, respectively). Alkaline phosphatase and creatine kinase concentrations were greater in young than in adult males (p < 0.05). In conclusion, the EE under general anaesthesia in the pampas deer provoked increases in heart and pulse rates, as well as in creatine kinase, aspartate aminotransferase and alkaline phosphatase concentrations, and a decrease in rectal temperature in both categories. Oximetry values were especially low during the procedure. Heart rate increase was greater in adult males, and alkaline phosphatase and creatine kinase concentrations were greater in yearlings. 相似文献
48.
Martín-Burriel I Rodellar C Cañón J Cortés O Dunner S Landi V Martínez-Martínez A Gama LT Ginja C Penedo MC Sanz A Zaragoza P Delgado JV 《Journal of animal science》2011,89(4):893-906
In Iberia there are 51 officially recognized cattle breeds of which 15 are found in Portugal and 38 in Spain. We present here a comprehensive analysis of the genetic diversity and structure of Iberian cattle. Forty of these breeds were genotyped with 19 highly polymorphic microsatellite markers. Asturiana de los Valles displayed the greatest allelic diversity and Mallorquina the least. Unbiased heterozygosity values ranged from 0.596 to 0.787. The network based on Reynolds distances was star-shaped with few pairs of interrelated breeds and a clear cluster of 4 breeds (Alistana/Arouquesa/Marinhoa/Mirandesa). The analysis of the genetic structure of Iberian cattle indicated that the most probable number of population clusters included in the study would be 36. Distance results were supported by the STRUCTURE software indicating a relatively recent origin or possible crossbreeding or both between pairs or small groups of breeds. Five clusters included 2 different breeds (Betizu/Pirenaica, Morucha/Avile?a, Parda de Monta?a/Bruna de los Pirineos, Barros?/Cachena, and Toro de Lidia/Brava de Lide), 3 breeds (Berrenda en Negro, Negra Andaluza, and Mertolenga) were divided in 2 independent clusters each, and 2 breeds were considered admixed (Asturiana de los Valles and Berrenda en Colorado). Individual assignation to breeds was not possible in the 2 admixed breeds and the pair Parda de Monta?a/Bruna de los Pirineos. The relationship between Iberian cattle reflects their geographical origin rather than their morphotypes. Exceptions to this geographic clustering are most probably a consequence of crossbreeding with foreign breeds. The relative genetic isolation within their geographical origin, the consequent genetic drift, the adaptation to specific environment and production systems, and the influence of African and European cattle have contributed to the current genetic status of Iberian cattle, which are grouped according to their geographical origin. The greater degree of admixture observed in some breeds should be taken into account before using molecular markers for genetic assignment of individuals to breeds. 相似文献
49.
S. Quirós Carmona R. Navarrete-CalvoM.M. Granados J.M. DomínguezJ. Morgaz J.A. Fernández-SarmientoP. Muñoz-Rascón R.J. Gómez-Villamandos 《Research in veterinary science》2014
Six Beagles were used in this prospective randomised crossover experimental study. Dexmedetomidine was administered at 0, 1 or 2 μg/kg IV for group C, LDA and HDA, respectively. Animals were induced and maintained with alfaxalone at 0.07 mg/kg/min with a CRI dexmedetomidine dose of 0, 0.5 or 1 μg/kg/h for group C, LDA and HDA, respectively. Cardiorespiratory variables, arterial blood gases and depth of anaesthesia were recorded. The recovery times and quality of recovery were scored. Group HDA produced a greater increase in the depth of anaesthesia than LDA. However, with both protocols, CI was halved compared to normal values in dogs. The use of oxygen before and during the anaesthetic maintenance is advisable, mainly if dexmedetomidine is going to be use as a pre-medicant and maintenance agent. The quality of recovery was better in groups receiving dexmedetomidine, without causing an increase in recovery time. 相似文献
50.
García-Bocanegra I Arenas-Montes A Lorca-Oró C Pujols J González MA Napp S Gómez-Guillamón F Zorrilla I Miguel ES Arenas A 《Veterinary research》2011,42(1):88
ABSTRACT: Although the importance of wild ruminants as potential reservoirs of bluetongue virus (BTV) has been suggested, the role played by these species in the epidemiology of BT in Europe is still unclear. We carried out a serologic and virologic survey to assess the role of wild ruminants in the transmission and maintenance of BTV in Andalusia (southern Spain) between 2006 and 2010.A total of 473 out of 1339 (35.3%) wild ruminants analyzed showed antibodies against BTV by both ELISA and serum neutralization test (SNT). The presence of neutralizing antibodies to BTV-1 and BTV-4 were detected in the four species analyzed (red deer, roe deer, fallow deer and mouflon), while seropositivity against BTV-8 was found in red deer, fallow deer and mouflon but not in roe deer. Statistically significant differences were found among species, ages and sampling regions. BTV RNA was detected in twenty-one out of 1013 wild ruminants (2.1%) tested. BTV-1 and BTV-4 RNA were confirmed in red deer and mouflon by specific rRT-PCR.BTV-1 and BTV-4 seropositive and RNA positive wild ruminants, including juveniles and sub-adults, were detected years after the last outbreak was reported in livestock. In addition, between the 2008/2009 and the 2010/2011 hunting seasons, the seroprevalence against BTV-1, BTV-4 and BTV-8 increased in the majority of provinces, and these serotypes were detected in many areas where BTV outbreaks were not reported in domestic ruminants. The results indicate that wild ruminants seem to be implicated in the dissemination and persistence of BTV in Spain. 相似文献