全文获取类型
收费全文 | 6363篇 |
免费 | 303篇 |
国内免费 | 506篇 |
专业分类
林业 | 672篇 |
农学 | 711篇 |
基础科学 | 319篇 |
568篇 | |
综合类 | 3062篇 |
农作物 | 263篇 |
水产渔业 | 7篇 |
畜牧兽医 | 304篇 |
园艺 | 897篇 |
植物保护 | 369篇 |
出版年
2024年 | 36篇 |
2023年 | 137篇 |
2022年 | 265篇 |
2021年 | 282篇 |
2020年 | 263篇 |
2019年 | 226篇 |
2018年 | 196篇 |
2017年 | 282篇 |
2016年 | 365篇 |
2015年 | 260篇 |
2014年 | 362篇 |
2013年 | 375篇 |
2012年 | 494篇 |
2011年 | 526篇 |
2010年 | 360篇 |
2009年 | 358篇 |
2008年 | 274篇 |
2007年 | 304篇 |
2006年 | 289篇 |
2005年 | 232篇 |
2004年 | 180篇 |
2003年 | 152篇 |
2002年 | 133篇 |
2001年 | 87篇 |
2000年 | 116篇 |
1999年 | 81篇 |
1998年 | 69篇 |
1997年 | 57篇 |
1996年 | 51篇 |
1995年 | 47篇 |
1994年 | 45篇 |
1993年 | 38篇 |
1992年 | 54篇 |
1991年 | 40篇 |
1990年 | 45篇 |
1989年 | 17篇 |
1988年 | 25篇 |
1987年 | 11篇 |
1986年 | 3篇 |
1985年 | 9篇 |
1984年 | 9篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1981年 | 4篇 |
1980年 | 2篇 |
1978年 | 5篇 |
1955年 | 2篇 |
排序方式: 共有7172条查询结果,搜索用时 140 毫秒
101.
Epidemiology and control of Menangle virus in pigs 总被引:6,自引:0,他引:6
Kirkland PD Love RJ Philbey AW Ross AD Davis RJ Hart KG 《Australian veterinary journal》2001,79(3):199-206
OBJECTIVE: To describe the epidemiology and eradication of Menangle virus infection in pigs. DESIGN: Field observations and interventions, structured and unstructured serological surveys, prospective and cross-sectional serological studies and laboratory investigations. PROCEDURE: Serum samples were collected from pigs at a 2600-sow intensive piggery in New South Wales that experienced an outbreak of reproductive disease in 1997. Serum samples were also collected from piggeries that received pigs from or supplied pigs to the affected piggery and from other piggeries in Australia. Serum and tissue samples were collected from pigs at piggeries experiencing reproductive disease in New South Wales. Sera and faeces were collected from grey-headed flying foxes (Pteropus poliocephalus) in the region of the affected piggery. Serum samples were tested for neutralising antibodies against Menangle virus. Virus isolation was attempted from faeces. RESULTS: Following the outbreak of reproductive disease, sera from 96% of adult pigs at the affected piggery, including sows that produced affected litters, contained neutralising antibodies against Menangle virus. Neutralising antibodies were also detected in sera from 88% of finisher pigs at two piggeries receiving weaned pigs from the affected piggery. No evidence of Menangle virus infection was found in other piggeries in Australia. In cross-sectional studies at the affected piggery, colostral antibodies were undetectable in most pigs by 14 to 15 weeks of age. By slaughter age or entry to the breeding herd, 95% of pigs developed high antibody titres (> or = 128) against Menangle virus in the virus neutralisation test. Menangle virus was eradicated from the affected piggery following a program of serological testing and segregation. Neutralising antibodies against Menangle virus were also detected in P poliocephalus from two colonies in the vicinity of the affected piggery. Two piggery workers were infected with Menangle virus. There was no evidence of infection in cattle, sheep, birds, rodents, feral cats and a dog at the affected piggery. CONCLUSIONS: Serological evidence of infection with Menangle virus was detected in pigs at a piggery that had experienced reproductive disease, in pigs at two associated piggeries and in fruit bats in the region of the piggery. Two humans were infected. The mode of transmission between pigs is unknown, but spread by faecal or urinary excretion is postulated. This virus can be eradicated by the segregation of pigs into discrete age groups. 相似文献
102.
103.
Thomas Thomidis 《Phytoparasitica》2001,29(1):47-49
The relative virulence ofPhytophthora cactorum andP. syringae originating from almond trees, and ofP. citrophthora originating from citrus, to apple, pear, peach, cherry and plum rootstocks, was studiedin vivo andin vitro. Results of the different experiments were in good agreement. All testedPhytophthora isolates showed little virulence to pear rootstocks-causing only minor crown rot symptoms - and no virulence at all to apple
rootstocks. In contrast, they were highly virulent to stone fruit rootstocks, causing crown rot disease. The non-pathogenicity
of these isolates to pome rootstocks could be interpreted as strict host specificity. 相似文献
104.
A technique for rearing the progeny of wildCeratitis capitata flies was developed. The method is based on wild captured flies which are allowed to oviposit in artificial fruit containing
larval rearing medium. Flies develop in the fruit from eggs to last larval instar, then exit the fruit and pupate within vermiculite.
This method was shown to be feasible and efficient, and to increase considerably the number of wild flies for testing purposes.
Possible contribution to the Sterile Insect Technique (SIT) and potential applications of the method are discussed. 相似文献
105.
106.
107.
108.
The distribution of olive fruit fly captures with McPhail traps within an olive orchard 总被引:1,自引:0,他引:1
Ioannis?DimouEmail author Constantin?Koutsikopoulos Aristidis?Economopoulos Josef?Lykakis 《Phytoparasitica》2003,31(2):124-131
The spatial distribution of olive fruit flyBactrocera (Dacus) oleae (Gmelin) (Diptera: Tephritidae) field captures with McPhail traps within an experimental orchard was evaluated. Contour maps
were constructed to examine the patterns in the 3-year trapping data. Captures varied widely inside the olive orchard, with
traps suspended on wild olive trees exhibiting the poorest performance. Favorable microclimate, created by a standing water
pool, appeared to be responsible for increased trap captures during the hot summer months. The positive role of the olive
tree fruit load is also discussed.
http://www.phytoparasitica.org posting Feb. 2, 2003. 相似文献
109.
The field efficacy of a bait containing phloxine B, uranine and Provesta 621 protein was tested against Mediterranean fruit fly (Ceratitis capitata; Medfly) by aerial and ground spraying in about 84 ha of coffee fields in Kauai, Hawaii, USA. Concurrently, soil and crop samples were collected from the aerially sprayed field and its unsprayed control field for residue studies. Efficacy of the sprays was assessed through trapping with both protein-baited and trimedlure-baited traps and through the infestation level of coffee cherries collected at least three-quarters ripe. The C capitata population was low at the start of the aerial and ground spray studies, but dramatically increased in the control fields. This increase coincided with initial ripening of coffee cherries. During times of peak population levels, C capitata populations were reduced by more than 91% in the ground-sprayed field and 99% in the aerial-sprayed field, relative to the populations in their respective control fields and based on protein-baited trap catches. Results of residue analyses indicated that uranine dissipated quickly compared with phloxine B on coffee and soil. Coffee samples collected at pre-spray periods had phloxine B residues of 7.2-25.5 ng g-1 on berries. Phloxine B concentrations were much higher on coffee leaves (163-1120 ng g-1). Lower concentrations of the dye were found from coffee samples collected during rainy days. Average phloxine B concentrations immediately after spraying were 56 and 2840 ng g-1 in coffee berries and leaves, respectively. Dissipation of phloxine B on berries was fast, with a half-life (t1/2) of 3 days. Dissipation of phloxine B on leaves was fitted to two linear phases: the initial (0-4 days) with a shorter t1/2 of 3 days and the later phase (4-28 days) with a longer t1/2 of 15 days. Average concentrations of phloxine B in the top soil ranged from 50 to 590 ng g-1 at pre-spray. Phloxine B initial concentration (770 ng g-1) reached a plateau immediately after the last spraying, but showed a steady decline over time with t1/2 of 16 days. Fast dissipation of the dyes in the field indicates that these chemicals may be environmentally compatible and therefore a promising alternative for fruit fly control. 相似文献
110.
Hendra (equine morbillivirus) 总被引:2,自引:0,他引:2
Hendra has been recognized in Australia as a new zoonotic disease of horses since 1994/5 and subsequent work has shown that the viral agent is endemic in certain species of fruit bat. The Hendra virus is the type species of a new genus within the sub-family Paramyxovirinae, which also contains another newly identified zoonotic bat virus, namely Nipah. It is assumed that contact with bats has led to the Hendra virus being transferred to horses on each of the three separate incidents that have been reported in the last five years. No evidence has been found for widespread subclinical infection of horses.Infected horses can develop a severe and often fatal respiratory disease characterized by dyspnoea, vascular endothelial damage and pulmonary oedema. Nervous signs may also occur. Fatal respiratory disease has been seen in cats and guinea pigs following experimentally induced infections. Transmission of the virus from horses to other horses or man seems to have taken place, but very close contact was required. Three human cases have been recognized, all in association with equine cases. There have been two human fatalities, one due to respiratory failure and the other from a delayed-onset encephalitis. A number of diagnostic methods have been developed, but great care must be taken in obtaining samples from suspected cases. 相似文献