全文获取类型
收费全文 | 170411篇 |
免费 | 9366篇 |
国内免费 | 93篇 |
专业分类
林业 | 7200篇 |
农学 | 5625篇 |
基础科学 | 1177篇 |
20250篇 | |
综合类 | 30580篇 |
农作物 | 6689篇 |
水产渔业 | 8397篇 |
畜牧兽医 | 87579篇 |
园艺 | 2136篇 |
植物保护 | 10237篇 |
出版年
2018年 | 2343篇 |
2017年 | 2694篇 |
2016年 | 2512篇 |
2015年 | 2132篇 |
2014年 | 2543篇 |
2013年 | 6552篇 |
2012年 | 4670篇 |
2011年 | 5766篇 |
2010年 | 3853篇 |
2009年 | 3778篇 |
2008年 | 5738篇 |
2007年 | 5291篇 |
2006年 | 5103篇 |
2005年 | 4586篇 |
2004年 | 4578篇 |
2003年 | 4546篇 |
2002年 | 4329篇 |
2001年 | 5633篇 |
2000年 | 5525篇 |
1999年 | 4242篇 |
1998年 | 1769篇 |
1997年 | 1830篇 |
1996年 | 1632篇 |
1995年 | 1945篇 |
1994年 | 1812篇 |
1993年 | 1780篇 |
1992年 | 3622篇 |
1991年 | 3837篇 |
1990年 | 3766篇 |
1989年 | 3742篇 |
1988年 | 3388篇 |
1987年 | 3422篇 |
1986年 | 3553篇 |
1985年 | 3431篇 |
1984年 | 2757篇 |
1983年 | 2480篇 |
1982年 | 1696篇 |
1981年 | 1574篇 |
1979年 | 2533篇 |
1978年 | 2006篇 |
1977年 | 1629篇 |
1976年 | 1648篇 |
1975年 | 1782篇 |
1974年 | 2189篇 |
1973年 | 2210篇 |
1972年 | 2127篇 |
1971年 | 2076篇 |
1970年 | 1979篇 |
1969年 | 1840篇 |
1967年 | 1642篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
R Malik D I Wigney D Dawson P Martin G B Hunt D N Love 《Journal of Feline Medicine and Surgery》2000,2(1):35-48
Mycobacteria were isolated and characterised from 49 cats with extensive infections of the subcutis and skin. Cats were generally between 3 and 10 years of age, and female cats were markedly over-represented. All isolates were rapid-growers and identified as either Mycobacteria smegmatis (40 strains) or M fortuitum (nine strains). On the basis of Etest for minimum inhibitory concentration and/or disc diffusion susceptibility testing, all strains of M smegmatis were susceptible to trimethoprim while all strains of M fortuitum were resistant. M smegmatis strains were typically susceptible to doxycycline, gentamicin and fluoroquinolones but not clarithromycin. All M fortuitum strains were susceptible to fluoroquinolones, and often also susceptible to gentamicin, doxycycline and clarithromycin. Generally, M smegmatis strains were more susceptible to antimicrobial agents than M fortuitum strains. Treatment of mycobacterial panniculitis involves long courses of antimicrobial agents, typically of 3-6 months, chosen on the basis of in vitro susceptibility testing and often combined with extensive surgical debridement and wound reconstruction. These therapies will result in effective cure of the disease. One or a combination of doxycycline, ciprofloxacin/enrofloxacin or clarithromycin are the drugs of choice for long-term oral therapy. 相似文献
992.
S H Binns S Dawson A J Speakman L E Cuevas C A Hart C J Gaskell K L Morgan R M Gaskell 《Journal of Feline Medicine and Surgery》2000,2(3):123-133
A cross-sectional survey of a convenience sample of cats was carried out to determine the prevalence of and risk factors for respiratory tract disease, feline calicivirus (FCV) infection and feline herpesvirus (FHV) infection. Seven hundred and forty cats were studied; samples for isolation of FCV and FHV were obtained from 622 (84%). Data on individual cat and household variables were obtained by questionnaire for each cat and analysed using univariable and logistic regression analysis. Thirty-eight percent (282/740) of cats surveyed had respiratory tract disease. Eighteen of 24 predictor variables were found to be significantly (P<0.05) associated with the presence of respiratory tract disease in a cat on univariable analysis. Following logistic regression, several factors retained significance including isolation of FCV and FHV, younger cats (4-11 months of age) and multiple cat households. A negative association was found with breeding catteries and other types of household in comparison with rescue catteries. Overall, feline calicivirus was isolated from 162/622 (26%) of cats sampled; 33% of the cats with respiratory tract disease were FCV positive compared to 21% of healthy cats. Variables significantly associated with FCV isolation on logistic regression were the presence of respiratory tract disease and contact with dogs with and without respiratory tract disease. Feline herpesvirus was isolated from 30/622 (5%) of all cats sampled; 11% of cats with respiratory tract disease were FHV positive compared to 1% of healthy cats. Variables significantly associated with FHV isolation on univariable analysis included age, gender, and the presence of respiratory tract disease. Vaccination showed a negative association. Logistic regression analysis of the data for FHV was limited by the sample size and the low prevalence of FHV. 相似文献
993.
CASE: An 11-year-old female domestic shorthaired cat presenting with clinical signs of depression, anorexia, weight loss, fever, anaemia and a mid-abdominal mass was referred for abdominal ultrasound examination. CLINICAL FINDINGS: Ultrasonography of the abdomen identified a markedly enlarged spleen. Ultrasound-guided fine-needle aspiration biopsy of the spleen revealed a uniform population of mast cells, 11% of which were observed to have phagocytosed erythrocytes. It is speculated that this may have been a contributing factor in the development of anaemia in this case. Mast cells were detected in a peripheral-blood smear and a diagnosis of systemic mastocytosis (splenic mast cell tumour together with mastocytaemia) was made. This diagnosis was subsequently confirmed by histopathology of the spleen. CONCLUSION: Splenectomy and treatment with corticosteroids appears to have resulted in remission of clinical signs and anaemia. A reduction in the concentration of mast cells in the peripheral blood had not occurred 6 weeks postsplenectomy, but was evident by 10 months post-splenectomy. 相似文献
994.
Capece BP Castells G Pérez F Arboix M Cristòfol C 《Veterinary research communications》2000,24(5):339-348
Benzimidazole anthelmintic drugs are widely used in veterinary practice. Albendazole sulphoxide (ABZSO) is a benzimidazole drug with two enantiomers, as a consequence of a chiral centre in the sulphoxide group. The kinetics of these enantiomers were studied in male and female sheep. Plasma samples were obtained from the animals between 0.5 and 72 h after oral administration of 7.5 mg/kg of a racemic formulation of ABZSO (total-ABZSO). After a liquid–liquid extraction, the samples were analysed by HPLC to determine the concentrations of total-ABZSO and of the sulphone metabolite (ABZSO2). During the chromatographic analysis, the ABZSO peak was collected and reanalysed by an HPLC technique using a Chiral AGP column to quantify the enantiomeric proportion therein. After kinetic analysis, the AUCs obtained for the (+)-ABZSO were 5.8 and 4.0 times higher than those for the (–)-ABZSO in male and female animals, respectively. The mean residence times were 23.4 and 16.1 h for (+)-ABZSO and 22.2 and 17.4 h for (–)-ABZSO for male and female animals, respectively. The only significant difference between the sexes (p<0.05) was in the T
max of the (–)-ABZSO. Comparing both enantiomers within each sex, significant differences were found in all the kinetic parameters. Finally, no kinetic differences were found between sex for total-ABZSO or ABZSO2. 相似文献
995.
Nielsen R van den Bosch JF Plambeck T Sørensen V Nielsen JP 《Veterinary microbiology》2000,71(1-2):81-87
The reference strains of the 12 serotypes of Actinobacillus pleuropneumoniae express one or two of three different RTX exotoxins designated Apx I, Apx II and Apx III. The toxins are important virulence factors. In the present study, ELISAs with purified Apx I, Apx II and Apx III, respectively, as antigen were evaluated as candidates for serological diagnosis of Actinobacillus pleuropneumoniae infection in pigs. The pigs were inoculated with biotype 1, serotypes 1-12, and biotype 2, serotype 14, respectively. A strong humoral antibody response was seen to all the three antigens in most pigs irrespective of the serotype used for inoculation. However, titers to the exotoxins secreted by the serotype used for inoculation were generally highest. The results show that toxin proteins of Actinobacillus pleuropneumoniae are antigenically related and that a correlation between serotype and secretion of exotoxin is not revealed serologically in the ELISA test. 相似文献
996.
Platt SR Helmick KE Graham J Bennett RA Phillips L Chrisman CL Ginn PE 《Journal of the American Veterinary Medical Association》1999,214(8):1218-20, 1200
Clinical, electromyographic, and pathologic findings characteristic of lead toxicosis were detected in a turkey vulture (Cathartes aura). The bird had generalized lower motor neuron dysfunction that progressed over 5 days. Electromyography revealed diffuse denervation potentials and a presumed decrement in the sciatic-tibial nerve conduction velocity. Histologic examination of peripheral nerves obtained at necropsy revealed changes that could be compatible with lead-induced neuropathy. Lead toxicosis was confirmed by determination of blood lead concentrations. Lead toxicosis causing neurologic disorders in birds has been described. However, this report emphasizes the effects of lead on the peripheral nervous system and demonstrates the use of electromyography for diagnosis of peripheral neuropathy in birds. 相似文献
997.
Jacobson LS Schoeman T Lobetti RG 《Journal of the South African Veterinary Association》2000,71(4):222-228
South Africa appears to be the only country where feline babesiosis is a significant clinical entity in domestic cats. Little is known about its epidemiology or the clinical challenges facing practitioners. A questionnaire posted to 1760 South African veterinarians was returned by 16%, representing approximately 40% of practices. Just over half reported seeing feline babesiosis, with most cases occurring in the coastal areas of the Western Cape, Eastern Cape and KwaZulu-Natal Provinces. Overall incidence is highest in summer, but seasonality is less pronounced in non-seasonal and winter rainfall areas. No age, breed or sex predisposition was identified. Weight loss, weakness, anaemia, fever and icterus are common clinical findings. Complications include hepatopathy, renal failure, pulmonary oedema, cerebral signs, immune-mediated haemolytic anaemia and concurrent infections. The antibabesial drug of choice is primaquine phosphate. Response to therapy is generally good, but recurrence and chronic infections were identified as problems. The average mortality rate was 15%. Approximately 3000 cases are seen annually by the respondents, at an estimated cost of R750 000 to the owners. Feline babesiosis is a significant problem in South Africa, and further investigations of taxonomic status, concurrent infections, chemotherapy, complications and management of refractory cases are warranted. 相似文献
998.
Rosochacki SJ Piekarzewska AB Połoszynowicz J Sakowski T 《Journal of veterinary medicine. A, Physiology, pathology, clinical medicine》2000,47(4):231-242
Forty-five Duroc (recognized as not susceptible to stress) and 34 Pietrain (susceptible to stress) pigs were subjected to immobilization stress in a prone position for 5, 15, 30 and 60 min. Plasma concentrations of epinephrine (E), norepinephrine (NE), dopamine (DA) and cortisol (C) were determined in response to restraint stress. The concentrations of E, NE and DA were different between the two strains of pigs (some significant interactions); the highest response was seen after 5 min of stress. The concentration of plasma C increased with duration of stress and there was a significant interaction between strain of animals and the time of stress. Our data substantiate the use of E, NE, DA and C as indicators of stress in swine as early as 5 min after exposure to the stressor. It is also shown that stress-susceptible Pietrain pigs had higher plasma concentrations of E, NE and DA than Duroc pigs. 相似文献
999.
Paulsen DB Kern MR Weigand CM 《Journal of the American Veterinary Medical Association》2000,216(10):1589-91, 1569
A 2-year-old spayed female domestic shorthair cat was referred for evaluation of rapidly progressive lameness of the right hind limb, which was paralyzed. Histologic examination of biopsy specimens revealed pyogranulomatous inflammation affecting the sciatic, common peroneal, and tibial nerves, and slender, beaded, acid-fast bacilli within macrophages, nerve fibers, and degenerate axons. A diagnosis of mycobacterial neuritis was made and the cat was treated with clofazimine and enrofloxacin for extended periods. Treatment was partially effective; the goal of returning normal function to the limb was not achieved, but disease progression was halted and the cat remained a viable pet. 相似文献
1000.
Pluimers FH de Leeuw PW Smak JA Elbers AR Stegeman JA 《Preventive veterinary medicine》1999,42(3-4):139-155
The central and regional organisation of the campaign to eradicate the CSF epidemic in the Netherlands in 1997/1998 is described. The main instruments used in the campaign were based on stamping-out and movement restrictions specified by the European Union. Additional instruments were used for the first time, namely, pre-emptive culling of contact and neighbouring farms, compartmentalisation of transport, monthly serological screening in established surveillance areas and supervised repopulation of all farms in the former surveillance zone. Two other measures, the killing of very young piglets and a breeding ban were introduced to reduce production in established surveillance zones. Several factors complicated the eradication campaign, for instance, the late detection of the first infection; artificial insemination as a source of infection; the organisation of pig farming in the Netherlands, with its highly concentrated production and dependence on the transport of stock from one unit to another; insufficient rendering capacity; decreasing sensitivity of clinical inspection; and extremely high costs. 相似文献