全文获取类型
收费全文 | 299篇 |
免费 | 14篇 |
专业分类
林业 | 19篇 |
农学 | 12篇 |
基础科学 | 3篇 |
66篇 | |
综合类 | 18篇 |
农作物 | 18篇 |
水产渔业 | 17篇 |
畜牧兽医 | 134篇 |
园艺 | 3篇 |
植物保护 | 23篇 |
出版年
2024年 | 2篇 |
2023年 | 4篇 |
2022年 | 10篇 |
2021年 | 18篇 |
2020年 | 14篇 |
2019年 | 8篇 |
2018年 | 15篇 |
2017年 | 14篇 |
2016年 | 14篇 |
2015年 | 8篇 |
2014年 | 13篇 |
2013年 | 27篇 |
2012年 | 20篇 |
2011年 | 31篇 |
2010年 | 10篇 |
2009年 | 7篇 |
2008年 | 11篇 |
2007年 | 14篇 |
2006年 | 14篇 |
2005年 | 14篇 |
2004年 | 9篇 |
2003年 | 9篇 |
2002年 | 8篇 |
2001年 | 4篇 |
2000年 | 3篇 |
1999年 | 3篇 |
1998年 | 3篇 |
1995年 | 2篇 |
1994年 | 1篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1972年 | 1篇 |
排序方式: 共有313条查询结果,搜索用时 0 毫秒
91.
92.
Minniti D Borissova J Rejkuba M Alves DR Cook KH Freeman KC 《Science (New York, N.Y.)》2003,301(5639):1508-1510
The oldest and most metal-poor Milky Way stars form a kinematically hot halo, which motivates the two major formation scenarios for our galaxy: extended hierarchical accretion and rapid collapse. RR Lyrae stars are excellent tracers of old and metal-poor populations. We measured the kinematics of 43 RR Lyrae stars in the inner regions of the nearby Large Magellanic Cloud (LMC) galaxy. The velocity dispersion equals 53 +/- 10 kilometers per second, which indicates that a kinematically hot metal-poor old halo also exists in the LMC. This result suggests that our galaxy and smaller late-type galaxies such as the LMC have similar early formation histories. 相似文献
93.
Naylê Francelino Holanda Duarte Carlos Henrique Alencar Kellyn Kessiene de Sousa Cavalcante Francisco Gustavo Silveira Correia Phyllis Catharina Romijn Danielle Bastos Araujo Silvana Regina Favoretto Jorg Heukelbach 《Zoonoses and public health》2020,67(2):186-192
The intensification of dog, cat and livestock vaccination campaigns significantly reduced rabies cases in humans and domestic animals in Ceará State, Brazil. However, sylvatic animals—bats (order Chiroptera), wild canids, raccoons and non‐human primates— remain as reservoirs for the virus. Our hypothesis is that surveillance and monitoring of rabies virus in bats, especially passive surveillance, is of fundamental importance, besides the implementation of health education and strengthening of surveillance actions in humans exposed to aggressions. Thus, we assessed the occurrence of rabies virus in animals focusing on bats, before and after launching of the Sylvatic Rabies Surveillance Program in 2010. Surveillance data from the 184 municipalities of Ceará State were analysed, collected during the periods 2003–2010 (active surveillance) and 2011–2016 (passive surveillance), respectively. A total of 13,543 mammalian samples were received for rabies diagnosis from 2003 to 2016. Of these, 10,960 were from dogs or cats (80.9%), 1,180 from bats (8.7%), 806 from other sylvatic animals (foxes, marmosets, raccoons; 6.0%) and 597 from herbivores (cattle, goats, sheep, equines, pigs; 4.4%). A total of 588 (4.3%) samples were positive for rabies. About 8.4% (99/1,180) of the bat samples were infected with rabies virus, 92 (92.9%) of these were from non‐haematophagous bat species and 7 (7.1%) from haematophagous species. The number of bat samples received and infection rates increased considerably, after a shift from active surveillance (9/355 [2.5%] samples positive), to passive surveillance (90/825 [10.9%] samples positive). Surveillance of rabies virus in bats is fundamental for human and domestic animal health in Ceará State. Bats have to be considered as targets in surveillance and control programmes. Virus lineages should be characterized to increase knowledge on transmission dynamics of sylvatic rabies virus to domestic animals and the human population, and to provide additional evidence for planning and implementation of improved control measures. 相似文献
94.
Kunkes EL Simonetti DA West RM Serrano-Ruiz JC Gärtner CA Dumesic JA 《Science (New York, N.Y.)》2008,322(5900):417-421
It is imperative to develop more efficient processes for conversion of biomass to liquid fuels, such that the cost of these fuels would be competitive with the cost of fuels derived from petroleum. We report a catalytic approach for the conversion of carbohydrates to specific classes of hydrocarbons for use as liquid transportation fuels, based on the integration of several flow reactors operated in a cascade mode, where the effluent from the one reactor is simply fed to the next reactor. This approach can be tuned for production of branched hydrocarbons and aromatic compounds in gasoline, or longer-chain, less highly branched hydrocarbons in diesel and jet fuels. The liquid organic effluent from the first flow reactor contains monofunctional compounds, such as alcohols, ketones, carboxylic acids, and heterocycles, that can also be used to provide reactive intermediates for fine chemicals and polymers markets. 相似文献
95.
de Miranda e Silva Chaves Camila da Costa Ricardo Lopes Dias Duarte Keila Maria Roncato Beltrame Renato Travassos Quirino Celia Raquel 《Tropical animal health and production》2020,52(3):1345-1349
Tropical Animal Health and Production - The early pregnancy diagnosis allows optimizing production and timely management correction, with a greater reproductive output of livestock. The Idexx Rapid... 相似文献
96.
97.
Vashist U Falqueto AD Lustrino D Tunholi VM Tunholi-Alves VM dos Santos MA D'Agosto M Massard CL Pinheiro J 《Veterinary parasitology》2011,175(3-4):207-211
One of the species that causes avian malaria is Plasmodium juxtanucleare. It is commonly found in poultry, especially when the birds receive food free of coccidiostats. Since industrial and organic poultry breeding is increasing in the world and few studies have been conducted examining the clinical parameters of both healthy and infected birds, this work evaluated whether the infection caused by P. juxtanucleare in Gallus gallus provokes alterations in the birds' hepatic profile. We analyzed the activity of ALT and AST and carried out histological analyses of liver sections of infected fowls by intracelomic inoculation with infected blood from a donor fowl with a parasite load of around 7%. The infected birds' parasite load was evaluated during 45 days by means of blood smears. There was a positive correlation between the increase in parasite load and higher ALT activity in the infected fowls, but there was no significant variation of the AST activity between the control and infected groups, possibly because of the non-specificity of this enzyme as an indicator of hepatic lesion. The results show that infection caused by P. juxtanucleare in G. gallus provokes hepatic alterations, indicated by the increase in the ALT enzyme activity and by the inflammatory infiltrates found in the liver sections of the infected fowls. 相似文献
98.
Barros SC Ramos F Fagulha T Duarte M Henriques M Luís T Fevereiro M 《Veterinary microbiology》2011,152(3-4):407-410
The circulation of West Nile virus in Portugal was assessed by serological surveys conducted during 2004-2010 in horses and birds. The detection of WNV antibodies in both species in all the years covered by the study as well as the presence of anti-WNV IgM in symptomatic horses that had not traveled outside the country, support the notion that WNV circulates in Portugal. 相似文献
99.
Afonso SM Vaz Y Neves L Pondja A Dias G Willingham AL Vilhena M Duarte PC Jost CC Noormahomed EV 《Animal health research reviews / Conference of Research Workers in Animal Diseases》2011,12(1):123-129
The objective of this paper is to critically review and summarize available scientific and lay literature, and ongoing studies on human and porcine cysticercosis in Mozambique to identify knowledge gaps and direct immediate and long-term research efforts. Data on the spatial distribution and prevalence of the disease in human and swine populations are scarce and fragmented. Human serological studies have shown that 15-21% of apparently healthy adults were positive for cysticercosis antibodies or antigen, while in neuropsychiatric patients seroprevalence was as high as 51%. Slaughterhouse records indicate a countrywide occurrence of porcine cysticercosis, while studies have shown that 10-35% of pigs tested were seropositive for cysticercosis antibodies or antigen. Current research in Mozambique includes studies on the epidemiology, molecular biology, diagnosis and control of the disease. Future research efforts should be directed at better understanding the epidemiology of the disease in Mozambique, particularly risk factors for its occurrence and spread in human and swine populations, documenting the socio-economic impact of the disease, identifying critical control points and evaluating the feasibility and epidemiological impact of control measures and development of local level diagnostic tools for use in humans and swine. 相似文献
100.
Silvia Franco Andrade Daniel Silva Kupper Luiz Fernando Rodrigues de Pinho Elizabeth Cunha Franco Marcus Vin��cius Felix Fabri Prataviera Rodrigo Rolim Duarte Jos�� Ricardo Cec��lio Junqueira 《Journal of veterinary science (Suw?n-si, Korea)》2011,12(2):171-176
The objective of this study was to evaluate and validate the accuracy of the Perkins handheld applanation tonometer for measuring intraocular pressure (IOP) in horses and cattle. Both eyes of 10 adult horses and cattle were evaluated in a postmortem study. The eyes from 10 clinically normal adult horses and cattle were also examined after bilateral auriculopalpebral nerve block and topical anesthesia for an in vivo study. IOP was measured postmortem using direct manometry (measured with an aneroid manometer) and tonometry (measured with a Perkins handheld applanation tonometer). The correlation coefficients (r2) for the data from the postmortem manometry and Perkins tonometer study were 0.866 for horses and 0.864 for cattle. In the in vivo study, IOP in horses was 25.1 ± 2.9 mmHg (range 19.0~30.0 mmHg) as measured by manometry and 23.4 ± 3.2 mmHg (range 18.6~28.4 mmHg) according to tonometry. In cattle, IOP was found to be 19.7 ± 1.2 mmHg (range 18.0~22.0 mmHg) by manometry and 18.8 ± 1.7 mmHg (range 15.9~20.8 mmHg) by tonometry. There was a strong correlation between the IOP values obtained by direct ocular manometry and the tonometer in both horses and cattle. Our results demonstrate that the Perkins handheld tonometer could be an additional tool for accurately measuring IOP in equine and bovine eyes. 相似文献