全文获取类型
收费全文 | 1685篇 |
免费 | 116篇 |
国内免费 | 1篇 |
专业分类
林业 | 134篇 |
农学 | 61篇 |
基础科学 | 5篇 |
352篇 | |
综合类 | 97篇 |
农作物 | 111篇 |
水产渔业 | 155篇 |
畜牧兽医 | 670篇 |
园艺 | 36篇 |
植物保护 | 181篇 |
出版年
2024年 | 3篇 |
2023年 | 31篇 |
2022年 | 56篇 |
2021年 | 87篇 |
2020年 | 82篇 |
2019年 | 77篇 |
2018年 | 80篇 |
2017年 | 67篇 |
2016年 | 77篇 |
2015年 | 42篇 |
2014年 | 73篇 |
2013年 | 96篇 |
2012年 | 104篇 |
2011年 | 146篇 |
2010年 | 89篇 |
2009年 | 62篇 |
2008年 | 99篇 |
2007年 | 96篇 |
2006年 | 75篇 |
2005年 | 61篇 |
2004年 | 62篇 |
2003年 | 50篇 |
2002年 | 50篇 |
2001年 | 18篇 |
2000年 | 22篇 |
1999年 | 7篇 |
1998年 | 4篇 |
1997年 | 6篇 |
1996年 | 5篇 |
1995年 | 3篇 |
1994年 | 4篇 |
1993年 | 5篇 |
1992年 | 9篇 |
1991年 | 6篇 |
1990年 | 4篇 |
1988年 | 2篇 |
1987年 | 6篇 |
1986年 | 5篇 |
1985年 | 2篇 |
1984年 | 6篇 |
1981年 | 5篇 |
1975年 | 1篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1971年 | 1篇 |
1968年 | 1篇 |
1963年 | 1篇 |
1958年 | 1篇 |
1955年 | 2篇 |
1948年 | 2篇 |
排序方式: 共有1802条查询结果,搜索用时 11 毫秒
991.
Victor SR Crisóstomo FR Bueno FC Pagnocca FC Fernandes JB Correa AG Bueno OC Hebling MJ Bacci Júnior M Vieira PC da Silva MF 《Pest management science》2001,57(7):603-608
The development of Leucoagaricus gongylophorus, the fungus cultured by the leaf-cutting ant Atta sexdens was inhibited in vitro by synthetic compounds containing the piperonyl group. In addition, worker ants that were fed daily on an artificial diet to which these compounds were added had a higher mortality rate than the controls. The inhibition of the fungal growth increased with the size of the carbon side chain ranging from C1 through C8 and decreasing thereafter. 1-(3,4-Methylenedioxybenzyloxy)octane (compound 5) was the most active compound and inhibited the fungal development by 80% at a concentration of 15 micrograms ml-1. With worker ants the toxic effects started with compound 5 and increased with the number of carbons in the side chain. Thus, for the same concentration (100 micrograms ml-1) the mortality rates observed after 8 days of diet ingestion were 82%, 66% and 42%, for 1-(3,4-methylenedioxybenzyloxy)decane, 1-(3,4-methylenedioxybenzyloxy)dodecane and compound 5, respectively, whereas with commercial piperonyl butoxide the mortality was 68%. The latter compound, which is known as a synergist insecticide, was as inhibitory to the symbiotic fungus as the synthetic compound 5. The possibility of controlling these insects in the future using compounds that can target simultaneously both organisms is discussed. 相似文献
992.
993.
994.
Assis LM Bevilaqua CM Morais SM Vieira LS Costa CT Souza JA 《Veterinary parasitology》2003,118(1-2):43-49
The prevalence of antibodies to Neospora caninum was examined in six wild Artiodactyla species, and in five wild Carnivora species from Kenya. Blood sera (104 wild ungulates from Marula Estates (MEs), and 31 wild carnivores from Masai-Mara reserve and from other wildlife areas in northern and Southern Kenya), were screened using a Neospora agglutination test (NAT), with a twofold dilution (1:40-1:320 titres). Presence of NAT antibodies to N. caninun is reported here for the first time in zebra (Equus burchelli), eland (Taurotragus oryx), African buffalo (Syncerus caffer), Thompson gazelle (Gazella thompsoni), impala (Aepyceros melampus), warthog (Phacochoerus aethiopicus), spotted hyena (Crocuta crocuta) and in free-ranging cheetah (Acinonyx jubatus). At 1:80 dilution, prevalence was 61.5% in eland, 58.5% in zebra, 19.2% in Thompson gazelle, 33.3% in warthog, 50% in African buffalo, 30% in lion (Panthera leo), 20% in cheetah, and 33.3% in spotted hyena. Antibodies up to 1:320 titre were detected in eland (38.4%), zebra (19.5%), Thompson gazelle (3.8%) and lion (5%). Amongst herbivores, sero-prevalence was significantly (P<0.05) higher, at all dilutions, in "grazer/digger" species (e.g. eland and zebra) than in non-"grazer/digger" species (e.g. impala and Thompson gazelle). No antibodies to N. caninum were found in two leopards (Panthera pardus) and one serval (Felis serval). Our results indicates a steady presence of N. caninum in wild mammals from Kenya. The hypothesis of a sylvatic cycle of N. caninum could be suggested, but more data are needed to verify the hypothesis, as to evaluate the role of N. caninum infection on the dynamics of wild animals population in the study area. 相似文献
995.
996.
997.
Lavin S Lastras ME Marco I Cabañes FX 《Journal of veterinary medicine. B, Infectious diseases and veterinary public health》2000,47(3):225-227
A case of fibrinopurulent bronchopneumonia associated with Moraxella bovis infection in a chamois (Rupicapra pyrenaica) is described. The animal, a 4-month-old female, was referred by the staff warden of the National Game Reserve of Freser-Setcases (Catalonia, north-eastern Spain). The animal was in good general condition and was found 4 h before death. On necropsy the lungs were congested and oedematous, with haemorrhagic areas in the cranial and middle lobes. The microscopic lesions were those of a fibrinopurulent bronchopneumonia. Microbiological study of the samples obtained showed numerous small beta-haemolytic colonies in pure culture, identified as Moraxella (Moraxella) bovis. 相似文献
998.
Within Europe the question of plant coenosis is attracting growing interest. The quality and quantity of collected information
on forest resources at a global level largely depends on the capacity to collect and analyse data at national and sub-national
scale in a way compatible with those at global or continental levels. In Italy the acceptance of all the international agreements
and protocols on the protection of the environment and management of natural resources, requires a standardization of collected
information and statistics, with the aim to produce homogeneous and integrative data at global level. This need is reflected
in the following points: (1) the adoption of a classification system of land use and forest cover compatible with international
hierarchical systems and definitions; (2) the identification of standard procedures in data collection and data elaboration.
To classify natural resources and, in this case study, forest resources, implies to order natural and semi natural coenosis,
forest and pre-forest communities, in a systematic way, according to the applied variables and to the scale detail. The solution
proposed in this case study is organised according to forest management, through the adoption of the habitat approach, describing
forest and pre-forest types in a synoptic way and performing a system of nomenclature in agreement with the international
standards initiatives. In this way, the characterization of forest types at community level is related to the environmental
planning for the protection of biodiversity. 相似文献
999.
The element sulfur has an outstanding role in the crop protection chemistry because it is used in its elemental form as a multisite fungicide, but is also part of agrochemicals in the form of aromatic or aliphatic sulfur-containing rings or sulfur-based functional groups. This review gives an exhaustive overview over the latter category. Several fundamental agrochemical compound classes are named after a sulfur-based functionality, such as the dithiocarbamate fungicides and sulfonylurea herbicides. Altogether, 16 different sulfur-based functional groups are presented with their typical synthesis approaches and most important representatives in crop protection. © 2023 Society of Chemical Industry. 相似文献
1000.
Valente AL Parga ML Espada Y Lavin S Alegre F Marco I Cuenca R 《The Veterinary record》2007,161(7):226-232
Twenty live and five dead juvenile and subadult loggerhead sea turtles were examined ultrasonographically. Ten soft tissue areas of the integument were used as acoustic windows: cervical-dorsal and cervical-ventral, left and right cervicobrachial, left and right axillary, left and right prefemoral and left and right postfemoral windows. Anatomical cross-sections were performed on the dead turtles to provide reference data. The fourth and fifth cervical vertebrae, the spinal cord, and the venous sinuses of the external jugular vein were clearly visible through the cervical-dorsal acoustic window, and the oesophagus and the heart were imaged through the cervical-ventral acoustic window. The stomach was more frequently visible through the left axillary acoustic window. The liver could be imaged through both sides, but the right axillary acoustic window was better for visualising the gall bladder. The large and small intestines and the kidneys were visible through the right and left prefemoral acoustic windows; the kidneys were easily identified by their intense vasculature. 相似文献