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排序方式: 共有451条查询结果,搜索用时 31 毫秒
241.
The transmission of maedi-visna (MV) virus was studied within two groups of sheep, one of which was also affected with sheep pulmonary adenomatosis (SPA). Serological monitoring of sheep kept in contact with both groups indicated that MV virus replication occurred to a greater extent in the group with both diseases, three of five in-contact sheep being seropositive after 1 year's exposure compared with none of six held with MV-virus-only infected lambs. 相似文献
242.
S H Binns S Dawson A J Speakman L E Cuevas C J Gaskell C A Hart K L Morgan R M Gaskell 《The Veterinary record》1999,144(21):575-580
A cross-sectional survey of a convenience-sample of 740 cats was undertaken to obtain an estimate of the prevalence of Bordetella bronchiseptica infection, and to identify risk factors that might predispose them to the infection. Data on individual cats and household variables, including disease status and animal contacts were obtained by questionnaire. B bronchiseptica was isolated from 82 (11 per cent) of the cats sampled. The prevalence of B bronchiseptica varied with the type of household sampled, being 19.5 per cent in rescue catteries, 9 per cent in breeding catteries, 13.5 per cent in research colonies, and 0 per cent in household pets. On the basis of a univariable analysis, 19 of 29 predictor variables were found to be significantly associated with the isolation of B bronchiseptica, including an association with cats in rescue catteries, and with cats from premises with larger numbers of animals. Separate analysis of the rescue cattery subpopulation showed a highly significant association on multivariable analysis with current respiratory disease, suggesting that different risk factors may operate in this type of environment. In the whole sample there was also strong association with cats from households containing a dog with recent respiratory tract disease. The clinical signs observed in the B bronchiseptica-positive cats included sneezing, ocular and nasal discharges and coughing, although only the association with sneezing was statistically significant. There was no significant association between the isolation of B bronchiseptica and the isolation of respiratory viruses, suggesting that in some circumstances B bronchiseptica may be able to cause disease independently. 相似文献
243.
Quasispecies evolution of a hypervariable region of the feline calicivirus capsid gene in cell culture and persistently infected cats. 总被引:1,自引:0,他引:1
A D Radford M Bennett F McArdle S Dawson P C Turner R A Williams M A Glenn R M Gaskell 《Veterinary microbiology》1999,69(1-2):67-68
The study determines the sequence evolution of feline calicivirus both in cell culture and in persistently infected cats and relates this to changes in virus neutralisation. 相似文献
244.
A.R. McCracken W.M. Dawson Sally Watson Chanel Y. Allen 《European journal of plant pathology / European Foundation for Plant Pathology》2000,106(9):879-886
Species/variety mixtures of Salix are used as a disease control strategy for rust (Melampsora epitea Thum. var. epitea) in short rotation coppice (SRC). Six LET (larici-epitea typica) pathotypes and two LR (larici-retusae) pathotypes of M. epitea var. epitea and also M. caprearum were detected in Northern Ireland plantations in 1994 and 1995. Three of these, LET7, LET8 and NI5 were detected in plantations for the first time. The predominant pathotype on most varieties was LET1. Logistic analysis showed that this pathotype was less prevalent on Salix X dasyclados Wimm. and more prevalent on S. viminalis L. 'Bowles Hybrid' than on S. viminalis '683'. The Shannon-Weaver Index of diversity indicated that there was greater pathotype diversity in mixtures than on the constituent varieties in monoculture. There was also a general trend of increasing diversity as the season progressed. The lowest pathotype diversity was recorded on S. viminalis 'Bowles Hybrid'. Pathotype predominance and diversity have an impact on the sustainability of the crop. 相似文献
245.
中国饲料及饲料原料受霉菌毒素污染的调查报告 总被引:51,自引:8,他引:51
由于缺少试验数据和分析方法,霉菌毒素问题在中国还不能得到充分的认识。为了了解我国饲料及饲料原料受霉菌毒素污染的情况,我们进行了下面的试验研究。分别从华南、华北和华中的饲料厂、仓库及客户手中采集了109个样品,使用酶联免疫法测定各样品中的黄曲霉毒素B1、赭曲霉毒素、烟曲霉毒素、T-2毒素、玉米赤霉烯酮和呕吐毒素的含量。1样本采集从内蒙、宁夏、黑龙江、北京、辽宁、天津、湖南、湖北、河北、江苏、浙江、福建、广东、海南等省市采集31份玉米、21份全价饲料、27份植物蛋白饲料、12份菌体蛋白饲料和11份动物蛋白饲料和3个青贮饲… 相似文献
246.
247.
Coyne KP Jones BR Kipar A Chantrey J Porter CJ Barber PJ Dawson S Gaskell RM Radford AD 《The Veterinary record》2006,158(16):544-550
Recently, in the USA, virulent mutants of feline calicivirus (FCV) have been identified as the cause of a severe and acute virulent systemic disease, characterised by jaundice, oedema and high mortality in groups of cats. This severe manifestation of FCV disease has so far only been reported in the USA. However, in 2003, an outbreak of disease affected a household of four adult cats and an adult cat from a neighbouring household in the UK. Three of the adult cats in the household and the neighbouring cat developed clinical signs including pyrexia (39.5 to 40.5 degrees C), lameness, voice loss, inappetence and jaundice. One cat was euthanased in extremis, two died and one recovered. A postmortem examination of one of the cats revealed focal cellulitis around the right hock and right elbow joints. The principal finding of histopathological examinations of selected organs from two of the cats was disseminated hepatocellular necrosis with mild inflammatory infiltration. Immunohistology identified FCV antigen in parenchymal and Kupffer cells in the liver of both animals and in alveolar macrophages of one of them. In addition, calicivirus-like particles were observed by electron microscopy within the hepatocytes of one cat. FCV was isolated from two of the dead cats and from the two surviving cats. Sequence analysis showed that they were all infected with the same strain of virus, but that it was different from strains of FCV associated with the virulent systemic disease in cats in the USA. The outbreak was successfully controlled by quarantine in the owner's house. 相似文献
248.
We tested the ability of an international Weed Risk Assessment (WRA) protocol to predict invasion status of 230 alien plant species introduced via a botanical garden to tropical rainforest in Tanzania. The reliability and accuracy of WRA in discriminating between invaders and non-invaders was independently assessed using field data on species demography and distribution. The WRA rejected 83% of known invaders, and accepted 74% of non-invaders. Only 1% of accepted species were known invaders at the site. WRA performance varied among different growth forms, and underestimated the risks arising from palm species. Among those species that had naturalised, the WRA was better at identifying invaders of open rather than forest habitats. The WRA score was significantly correlated with how widespread species had become at the site, suggesting some capacity to predict spatial spread at a landscape scale. Knowledge of propagule pressure and residence time did not increase explanatory power. These results indicate that the WRA was able to discriminate between invaders and non-invaders with accuracy comparable to similar assessments in temperate and sub-tropical regions. It could be made more effective by weighting traits important in tropical forests e.g. certain growth forms, shade tolerance etc. more heavily. Such a modified WRA could be used successfully elsewhere in the palaeotropics as a screening tool to identify the risk of invasion arising from plants introduced for agroforestry, horticulture or landscaping. Given the increasing pressures on tropical forests and importance of agroforestry to local economies, the WRA protocol represents a useful conservation tool. 相似文献
249.
Clegg SR Coyne KP Dawson S Spibey N Gaskell RM Radford AD 《Veterinary microbiology》2012,157(1-2):78-85
Canine parvovirus (CPV) and feline panleukopaenia virus (FPLV) are two closely related viruses, which are known to cause severe disease in younger unvaccinated animals. As well as causing disease in their respective hosts, CPV has recently acquired the feline host range, allowing it to infect both cats and dogs. As well as causing disease in dogs, there is evidence that under some circumstances CPV may also cause disease in cats. This study has investigated the prevalence of parvoviruses in the faeces of clinically healthy cats and dogs in two rescue shelters. Canine parvovirus was demonstrated in 32.5% (13/50) of faecal samples in a cross sectional study of 50 cats from a feline only shelter, and 33.9% (61/180) of faecal samples in a longitudinal study of 74 cats at a mixed canine and feline shelter. Virus was isolated in cell cultures of both canine and feline origin from all PCR-positive samples suggesting they contained viable, infectious virus. In contrast to the high CPV prevalence in cats, no FPLV was found, and none of 122 faecal samples from dogs, or 160 samples collected from the kennel environment, tested positive for parvovirus by PCR. Sequence analysis of major capsid VP2 gene from all positive samples, as well as the non-structural gene from 18 randomly selected positive samples, showed that all positive cats were shedding CPV2a or 2b, rather than FPLV. Longitudinally sampling in one shelter showed that all cats appeared to shed the same virus sequence type at each date they were positive (up to six weeks), despite a lack of clinical signs. Fifty percent of the sequences obtained here were shown to be similar to those recently obtained in a study of sick dogs in the UK (Clegg et al., 2011). These results suggest that in some circumstances, clinically normal cats may be able to shed CPV for prolonged periods of time, and raises the possibility that such cats may be important reservoirs for the maintenance of infection in both the cat and the dog population. 相似文献
250.
Butler SA Phillips NJ Boe-Hansen GB Bo GA Burns BM Dawson K McGowan MR 《Reproduction in domestic animals = Zuchthygiene》2012,47(3):463-471
The primary objective of this study was to investigate the impact of animal-level factors including energy balance and environmental/management stress, on the ovarian function of Bos indicus heifers treated to synchronize ovulation. Two-year-old Brahman (BN) (n = 30) and BN-cross (n = 34) heifers were randomly allocated to three intravaginal progesterone-releasing device (IPRD) treatment groups: (i) standard-dose IPRD [Cue-Mate(?) (CM) 1.56 g; n = 17]; (ii) half-dose IPRD [0.78 g progesterone (P(4)); CM 0.78 g; n = 15]; (iii) half-dose IPRD + 300 IU equine chorionic gonadotrophin at IPRD removal (CM 0.78 g + G; n = 14); (iv) and a control group, 2× PGF(2α) [500 μg prostaglandin F(2α) (PGF(2α))] on Day -16 and -2 (n = 18). Intravaginal progesterone-releasing device-treated heifers received 250 μg PGF(2α) at IPRD insertion (Day -10) and IPRD removal (Day -2) and 1 mg oestradiol benzoate on Day -10 and -1. Heifers were managed in a small feedlot and fed a defined ration. Ovarian function was evaluated by ultrasonography and plasma P(4) throughout the synchronized and return cycles. Energy balance was evaluated using plasma insulin-like growth factor 1 (IGF-I) and glucose concentrations. The impact of environmental stressors was evaluated using plasma cortisol concentration. Heifers that had normal ovarian function had significantly higher IGF-I concentrations at commencement of the experiment (p = 0.008) and significantly higher plasma glucose concentrations at Day -2 (p = 0.040) and Day 4 (p = 0.043), than heifers with abnormal ovarian function. There was no difference between the mean pre-ovulatory cortisol concentrations of heifers that ovulated or did not ovulate. However, heifers that ovulated had higher cortisol concentrations at Day 4 (p = 0.056) and 6 (p = 0.026) after ovulation than heifers that did not ovulate. 相似文献