全文获取类型
收费全文 | 1462篇 |
免费 | 169篇 |
专业分类
林业 | 137篇 |
农学 | 84篇 |
基础科学 | 14篇 |
344篇 | |
综合类 | 48篇 |
农作物 | 55篇 |
水产渔业 | 187篇 |
畜牧兽医 | 615篇 |
园艺 | 26篇 |
植物保护 | 121篇 |
出版年
2024年 | 3篇 |
2023年 | 27篇 |
2022年 | 24篇 |
2021年 | 66篇 |
2020年 | 77篇 |
2019年 | 68篇 |
2018年 | 106篇 |
2017年 | 114篇 |
2016年 | 105篇 |
2015年 | 61篇 |
2014年 | 82篇 |
2013年 | 90篇 |
2012年 | 111篇 |
2011年 | 115篇 |
2010年 | 61篇 |
2009年 | 41篇 |
2008年 | 70篇 |
2007年 | 66篇 |
2006年 | 65篇 |
2005年 | 83篇 |
2004年 | 55篇 |
2003年 | 47篇 |
2002年 | 29篇 |
2001年 | 15篇 |
2000年 | 17篇 |
1999年 | 7篇 |
1998年 | 3篇 |
1997年 | 4篇 |
1996年 | 3篇 |
1995年 | 3篇 |
1994年 | 2篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1990年 | 3篇 |
1989年 | 1篇 |
1985年 | 3篇 |
1969年 | 1篇 |
1960年 | 1篇 |
排序方式: 共有1631条查询结果,搜索用时 15 毫秒
151.
152.
153.
A.A. Macedo E.A. Costa A.P.C. Silva T.A. Paixão R.L. Santos 《Veterinary immunology and immunopathology》2013,151(3-4):294-302
154.
O. Gonzales-Viera J. Marigo V. Ruoppolo F.C.W. Rosas C.T. Kanamura C. Takakura A. Fernández J.L. Catão-Dias 《Veterinary parasitology》2013,191(3-4):358-362
This study describes toxoplasmosis in a by caught Guiana dolphin (Sotalia guinensis) from Paranaguá Bay, Paraná, Brazil. Interstitial pneumonia, multisystemic arteritis, multifocal adrenalitis and hepatitis were the primary lesions observed. These tissues had moderate to severe necrosis and mononuclear cells infiltration usually surrounded by tachyzoites and tissue cysts. Moderate lymphoid depletion was evident in the spleen. Toxoplasma gondii was positive by immunohistochemical and ultrastructural evaluation. Furthermore, the animal was negative for Morbillivirus by immunohistochemistry and had low levels of persistent organochlorines. There is evidence of environmental changes in the Paranaguá Bay that could justify the occurrence of toxoplasmosis in Guiana dolphin. The sewage run-off from main urban areas and the presence of domestic and wild felids in areas surrounding the bay could be a source of T. gondii oocysts from land to sea. Based on its habitat, the authors recommend this dolphin species as sentinels for the health of bays and estuaries where they occur. 相似文献
155.
Tatiana da Rosa Guimar?es Carlos Guillermo Quiroz Caroline Rigotto Simone Quintana de Oliveira Maria Tereza Rojo de Almeida éverson Miguel Bianco Maria Izabel Goulart Moritz Jo?o Luís Carraro Jorge Alejandro Palermo Gabriela Cabrera Eloir Paulo Schenkel Flávio Henrique Reginatto Cláudia Maria Oliveira Sim?es 《Marine drugs》2013,11(11):4176-4192
The n-butanol fraction (BF) obtained from the crude extract of the marine sponge Petromica citrina, the halistanol-enriched fraction (TSH fraction), and the isolated compounds halistanol sulfate (1) and halistanol sulfate C (2), were evaluated for their inhibitory effects on the replication of the Herpes Simplex Virus type 1 (HSV-1, KOS strain) by the viral plaque number reduction assay. The TSH fraction was the most effective against HSV-1 replication (SI = 15.33), whereas compounds 1 (SI = 2.46) and 2 (SI = 1.95) were less active. The most active fraction and these compounds were also assayed to determine the viral multiplication step(s) upon which they act as well as their potential synergistic effects. The anti-HSV-1 activity detected was mediated by the inhibition of virus attachment and by the penetration into Vero cells, the virucidal effect on virus particles, and by the impairment in levels of ICP27 and gD proteins of HSV-1. In summary, these results suggest that the anti-HSV-1 activity of TSH fraction detected is possibly related to the synergic effects of compounds 1 and 2. 相似文献
156.
A. R. Chaves M. P. de Campos M. B. L. Barros C. N. do Carmo I. D. F. Gremião S. A. Pereira T. M. P. Schubach 《Zoonoses and public health》2013,60(2):149-153
This study describes the epidemiological, clinical and mycological aspects of feline sporotrichosis cases attending the Laboratory of Clinical Research on Dermatozoonosis in Domestic Animals – Evandro Chagas Clinical Research Institute (LAPCLIN‐DERMZOO/IPEC/FIOCRUZ), from 1998 to 2005. It was possible to get in contact with 147 (19.2%) cat owners. One hundred and thirteen (76.9%) cats were male, 117 (79.6%) had no defined race and 87 (59.2%) were sexually intact. The age ranged from 72 to 216 months (median = 108 months). Nineteen cats were reassessed: eleven (57.8%) were male, thirteen (36.8%) were breed and fifteen (47.3%) castrated. Fourteen (52.6%) animals lived at home and did not roamed the streets. Seven (36.8%) had normal clinical findings and negative mycological examination. Twelve (63.1%) cats had skin lesions compatible with sporotrichosis. Thirty‐one (21%, n = 147) cats disappeared after abandoning treatment, 36 (24.5%, n = 147) were alive and 80 (54.4%, n = 147) had died. Causes of death informed by the owners were: sporotrichosis in 35 (43.7%, n = 80), accidental death in 27 (33.7%, n = 80) and other diseases in 18 (22.5%, n = 80). Withdrawal of treatment occurred mainly at the time of clinical improvement and may represent a serious obstacle to the control of sporotrichosis. 相似文献
157.
Schossler Thiago Rodrigo Mantovanelli Bruno Campos de Almeida Brivaldo Gomes Freire Fernando José da Silva Manassés Mesquita de Almeida Ceres Duarte Guedes Cabral Freire Maria Betânia Galvão dos Santos 《Precision Agriculture》2019,20(6):1274-1291
Precision Agriculture - Sugarcane productivity is highly variable across space, and knowledge about the spatial distribution of soil physical attributes is important to guide management practices... 相似文献
158.
Nilmara P. Caires Pollyane S. Hermenegildo Lúcio M. S. Guimares Reginaldo G. Mafia Edival . V. Zauza Norton Borges Júnior Jorge L. Badel Acelino C. Alfenas 《Forest Pathology》2019,49(4)
Dieback caused by Erwinia psidii is currently one of the most important emerging diseases in eucalypt plantations in Brazil. However, little is known in terms of the host range of this pathogen or the potential sources of resistance against the disease it causes. In this study, we inoculated plants of species from nine families to gain insight into the host range of E. psidii. Plants of all inoculated species of Myrtaceae except Acca sellowiana exhibited disease symptoms and therefore represent potential hosts for the pathogen under natural conditions. In addition, the response of four Corymbia species, 29 Eucalyptus species and three interspecific Eucalyptus hybrids to inoculation with E. psidii was evaluated. All Corymbia henryi, Corymbia maculata, Eucalyptus thozetiana, Eucalyptus cloeziana, Eucalyptus viminalis, Eucalyptus dalrympleana and Eucalyptus pilularis plants were highly resistant to the pathogen, whereas differential disease resistance was observed in the other species. This study provides important information on sources of resistance to Erwinia psidii with potential use in the development of clones with enhanced resistance in eucalypt species of economic importance. 相似文献
159.
Luciano Rodrigo Lanssanova Sebastião do Amaral Machado Alexandre Techy de Almeida Garrett Izabel Passos Bonete Allan Libanio Pelissari Afonso Figueiredo Filho 《Southern Forests》2019,81(2):167-173
This study evaluated the efficiency of taper functions and the application of mixed-effect modelling for diameter estimation along the stems of Tectona grandis. We sampled 266 trees of Tectona grandis, measuring the diameter at relative heights for volume determination, grouping the data according to three form-factor classes. Six taper functions were fitted, selecting the function with better fit performance. Six taper functions were fitted, selecting the function with better fit performance. The selected function was fitted in its basic formulation, and with the mixed non-linear modelling technique in different scenarios, and for the stem stratified in three portions of the total height. The precision and selection of the adjusted models were evaluated regarding the coefficient of determination, standard error of estimate, the Akaike information criterion, bias, quadratic error and absolute bias. According to the statistical criteria used, the model of Kozak was selected for the adjustments. For diameter estimation, the scenario with two coefficients as random effects provided an accuracy increase of 11.91%, and the mixed non-linear modelling better estimated the stem diameter for the stratified stems. In conclusion, the model of Kozak can be used to describe the stem shape of Tectona grandis, and the mixed-effect non-linear model approach was the best technique to estimate diameter along the stem of Tectona grandis. 相似文献
160.
Dos Santos Freitas L de Oliveira JV Dariva C Jacques RA Caramão EB 《Journal of agricultural and food chemistry》2008,56(8):2558-2564
The main objective of this work was to compare the extraction of grape seed oil with compressed carbon dioxide and propane on the extraction yields and chemical characteristics of free glycerol compounds. The experiments were performed in a laboratory scale unit in the temperature range of 30 to 60 degrees C and pressures from 60 to 254 bar. The results showed that propane is a more suitable solvent for grape seed oil extraction than carbon dioxide, as higher extractions yields and a very fast kinetic of extraction were achieved with this solvent. In relation to compressed carbon dioxide extractions, both temperature and density presented a very pronounced and positive effect on the extraction yield. The oils extracted were analyzed qualitatively and quantitatively with regard to the free glycerol compounds, mainly fatty acids, ethyl, and methyl esters. The results showed that these compounds are present in low concentration in vegetable oil (<3%) and that, in general, samples extracted with propane present a smaller amount of peaks of free glycerol compounds in the oil than samples extracted with carbon dioxide. 相似文献