全文获取类型
收费全文 | 590篇 |
免费 | 65篇 |
国内免费 | 2篇 |
专业分类
林业 | 14篇 |
农学 | 28篇 |
基础科学 | 2篇 |
105篇 | |
综合类 | 35篇 |
农作物 | 26篇 |
水产渔业 | 44篇 |
畜牧兽医 | 349篇 |
园艺 | 13篇 |
植物保护 | 41篇 |
出版年
2023年 | 5篇 |
2022年 | 4篇 |
2021年 | 12篇 |
2020年 | 18篇 |
2019年 | 21篇 |
2018年 | 35篇 |
2017年 | 14篇 |
2016年 | 23篇 |
2015年 | 21篇 |
2014年 | 29篇 |
2013年 | 48篇 |
2012年 | 11篇 |
2011年 | 28篇 |
2010年 | 30篇 |
2009年 | 25篇 |
2008年 | 38篇 |
2007年 | 23篇 |
2006年 | 36篇 |
2005年 | 21篇 |
2004年 | 26篇 |
2003年 | 16篇 |
2002年 | 17篇 |
2001年 | 15篇 |
2000年 | 16篇 |
1999年 | 16篇 |
1998年 | 20篇 |
1997年 | 13篇 |
1996年 | 16篇 |
1995年 | 13篇 |
1994年 | 4篇 |
1993年 | 4篇 |
1992年 | 8篇 |
1991年 | 3篇 |
1990年 | 2篇 |
1989年 | 5篇 |
1988年 | 6篇 |
1986年 | 4篇 |
1985年 | 1篇 |
1983年 | 1篇 |
1977年 | 1篇 |
1975年 | 2篇 |
1974年 | 1篇 |
1973年 | 3篇 |
1972年 | 2篇 |
排序方式: 共有657条查询结果,搜索用时 0 毫秒
591.
Assays dealing with the therapeutic and prophylactic activity of isometamidium on experimental infections by Trypanosoma vivax and T. evansi were carried out. The drug was found to be highly effective against T. vivax infection in sheep and cattle in which periods of protection ranging from 118 to 195 days were achieved. No complete effects against infection by T. evansi were observed. The drug was well tolerated in sheep and cattle while side-effects were noted in treated mares. It was concluded that isometamidium could be used to prevent damage and economical losses caused by T. vivax in Venezuela. 相似文献
592.
Donald M. Myers Alfonzo Ruiz Lennox Applewhaite 《Tropical animal health and production》1985,17(4):239-243
Summary Cattle sera collected in the Republic of Guyana during 1981 to 1982 were examined for serologic evidence of leptospirosis.
Significant leptospiral agglutinins (1∶100 or higher) were disclosed in 49·1% of 2,935 apparently normal cattle from 734 farms
in the three major cattle-raising regions of the country. Seroreactions principally involvedhardjo andwolffi of the Sejroe serogroup,icterohaemorrhagiae, pomona, tarassovi, canicola andgrippotyphosa. A high proportion of reactions to one or more of different leptospiral serovars were observed in each of the three regions.
These variations were attributed to differences in environmental conditions and farming practices. The findings provided evidence
for the first time of the widespread occurrence of leptospirosis in cattle in Guyana caused by multiple leptospiral serovars.
Resumen Se examinaron sueros bovinos colectados durante 1981 y 1982, con el propósito de detectar aglutininas de leptospirosis. Mediante los análisis, se evidenció la enfermedad (titulos 1∶100 o superiores) en el 49,1% de 2.935 bovinos aparentemente sanos, en las tres principales regiones ganaderas del país. Las seroreacciones involucraron principalmente a lahardjo ywolffi del serogrupo Sejroe, lo mismo que a laicterohaemorrhagiae, pomona, tarassovi, canicola ygrippotyphosa. Se observó una alta proporción de reacciones a una o más serovars en cada una de las tres regiones estudiadas; estas se atribuyeron a prácticas de manejo diferentes, asi como a condiciones ambientales. El estudio, se concluye, proporcionó evidencia de la amplia distribición de la leptospirosis en Guyana.
Résumé On a recherché l'existence sérologique de la leptospirose dans des sérums de bovins de la République de Guyana récoltés en 1981 et 1982. Des agglutinines à un taux significatif (1∶100 et plus) ont été détectées chez 49,1% de 2935 animaux apparemment normaux répartis dans 734 fermes des trois grandes régions d'élevage du pays. Les réactions sérologiques touchent principalement les sérotypeshardio etwolfii du sérogroupe Sejroe,icterohaemorrhagiae pomona, tarassovi, canicola etgrippotyphosa. On note une importante proportion de réaction à un ou plusieurs des sérovars leptospiriens dans chacune des trois régions. Ces variations sont attribuées aux différences de conditions d'environnement et aux pratiques d'élevage. Pour la première fois, ces résultats apportent la preuve d'une répartition étendue de la leptospirose bovine en Guyana causée par plusieurs sérovars.相似文献
593.
I Caballero JM Vazquez F Centurión H Rodríguez-Martinez I Parrilla J Roca C Cuello EA Martinez 《Reproduction in domestic animals》2004,39(5):370-375
Sperm handling, associated to artificial reproduction technologies (ART) such as in vitro fertilization (IVF) or the use of flow cytometry for cell analysis or sorting imposes volumetric extension of the sperm suspension and decreases sperm viability, presumably because of the removal of seminal plasma (SP) components. This study evaluated whether a 10% v/v of autologous SP (retrieved from the same donor boar) or homologous SP (e.g. from any of the four fertile boars included, other than the one providing the spermatozoa) would differently affect the viability of boar spermatozoa subjected to large extension in a simple saline medium [phosphate-buffered saline and 0.1% ethylenediaminetetraacetic acid (EDTA), PBSm] to a concentration of 0.3 x 10(6) spermatozoa/ml and incubated for 2 h at 30 degrees C. Sperm viability was monitored as membrane integrity [using the fluorophore carboxyfluorescein diacetate (C-FDA) and propidium iodide (PI)], mitochondrial function (using the fluorophore R-123) and motility characteristics [using Computer Assisted Sperm Analysis (CASA)]. Substraction of the SP and extension followed by incubation in PBSm significantly (p < 0.05) decreased sperm viability, which could be restored by addition of autologous SP. Furthermore, exposure of the extended spermatozoa to homologous SP (from any other individual boar) significantly (p < 0.05) varied with the source of the sire; some boars exerting beneficial effects (even surpassing the effects of the autologous SP; p < 0.05) while at least one boar negatively (p < 0.05) influencing the viability of the incubated spermatozoa. It is concluded that SP should be present when incubating highly extended spermatozoa. As a result of the obvious differences among boars, it would be advantageous to examine the ability of SP to maintain sperm viability prior to the use of SP pools during sperm handling in vitro. 相似文献
594.
J.Th.J. Verhoeven J.W. Roenhorst D.-E. Lesemann E. Segundo L. Velasco L. Ruiz D. Janssen I.M. Cuadrado 《European journal of plant pathology / European Foundation for Plant Pathology》2003,109(9):935-941
Southern bean mosaic virus (SBMV) has been identified as the cause of a new disease in greenhouse-cultivated common bean (Phaseolus vulgaris), in the south-east of Spain. The identification was based on host range comparisons, morphological and serological characteristics of the virus, the size of its dsRNA species and the nucleotide sequence of an 810-bp fragment from ORF2. The virus could be clearly discriminated from the related sobemovirus Southern cowpea mosaic virus. This is the first report of SBMV in Spain. 相似文献
595.
596.
Veterinary Research Communications - 相似文献
597.
Mourad Baghour Kaoutar Ben Chekroun Juan Manuel Ruiz Sáez Luis Romero 《Journal of plant nutrition》2016,39(1):51-58
The effect of root temperatures on the uptake and content of iron (Fe) in different organs of potato plants was studied. Four different plastic covers were used (T1: transparent polyethylene; T2: white polyethylene; T3: white and black coextruded polyethylene), using plants without plastic covers as control (T0). The results of this study indicate that in treatments with the highest root temperature (T2 and T3), chelate-reductase activity significantly increased, that could enhance the uptake and subsequent accumulation of Fe in the different organs analyzed of the potato plant. In addition, the roots and particularly the tubers proved to be the main organs of Fe bioaccumulation in treatments T0, T2, T3, and T4. On the contrary, in the T1 treatment, the bioaccumulation of Fe was detected in the shoot (stems and leaves). Finally, the foliar bioindicators of Fe analyzed, chl a and b, carotenes, peroxidase activity and catalase activity reflected the foliar status of Fe. 相似文献
598.
599.
José M. Vidal Alexis Fonseca Pamela Ruiz Daniela Sepúlveda Carlos Carrasco Stefano Scilipoti Javier Barros Ariel Valenzuela Ricardo Saavedra Nathaly Ruiz-Tagle Homero Urrutia 《Journal of fish diseases》2023,46(1):1-15
This study evaluated the probiotic potential of the biofilm formed by the strain Pseudomonas sp. RGM2144 on rainbow trout survival. When challenged with the fish pathogen Flavobacterium psychrophilum, Pseudomonas sp. RGM2144 increased rainbow trout survival to 92.7 ± 1.2% (control: 35.3 ± 9.5%, p < .0001). The draft genome of Pseudomonas sp. RGM2144 is 6.8 Mbp long, with a completeness 100% and a contamination of 0.4%. The genome contains 6122 protein-coding genes of which 3564 (~60%) have known functions. The genome and phylogeny indicate that Pseudomonas sp. RGM2144 is a new species in the Pseudomonas genus, with few virulence factors, plasmids, and genes associated with antimicrobial resistance, suggesting a non-pathogenic bacterium with protective potential. In addition, the genome encodes for 11 secondary metabolite biosynthetic gene clusters that could be involved in the inhibition of F. psychrophilum. We suggest that Pseudomonas sp. RGM2144 may be applied as a probiotic in salmonid fish farming. 相似文献
600.
Marcelo Accioly Teixeira de Oliveira Hermann Behling Luiz Carlos Ruiz Pessenda Gisele Leite de Lima 《CATENA》2008
During the past 40 years colluvial and alluvial deposits have been used in Brazil as good indicators of regional landscape sensitivity to Quaternary environmental changes. In spite of the low resolution of most of the continental sedimentary record, geomorphology and sedimentology may favor palaeoenvironmental interpretation when supported by independent proxy data. This paper presents results obtained from pedostratigraphic sequences, in near-valley head sites of southern Brazilian highlands, based on geomorphologic, sedimentologic, micromorphologic, isotopic and palynologic data. Results point to environmental changes, with ages that coincide with Marine Isotopic Stages (MIS) 5b; 3; 2 and 1. During the late Pleistocene, although under temperatures and precipitation lower than today, the local record points to relatively wet local environments, where shallow soil-water saturated zones contributed to erosion and sedimentation during periods of climatic change, as during the transition between MIS 2 and MIS 1. Late Pleistocene events with ages that coincide with the Northern Hemisphere Younger Dryas are also depicted. During the mid Holocene, slope-wash deposits suggest a climate drier than today, probably under the influence of seasonally contrasted precipitation regimes. The predominance of overland flow-related sedimentary deposits suggests an excess of precipitation over evaporation that influenced local palaeohydrology. This environmental condition seems to be recurrent and explains how slope morphology had influenced pedogenesis and sedimentation in the study area. Due to relative sensitiveness, resilience and short source-to-sink sedimentary pathways, near-valley head sites deserve further attention in Quaternary studies in the humid tropics. 相似文献