首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   2316篇
  免费   127篇
  国内免费   2篇
林业   110篇
农学   132篇
基础科学   3篇
  372篇
综合类   156篇
农作物   271篇
水产渔业   186篇
畜牧兽医   1055篇
园艺   33篇
植物保护   127篇
  2023年   14篇
  2022年   25篇
  2021年   52篇
  2020年   37篇
  2019年   43篇
  2018年   58篇
  2017年   67篇
  2016年   69篇
  2015年   70篇
  2014年   99篇
  2013年   140篇
  2012年   163篇
  2011年   171篇
  2010年   118篇
  2009年   122篇
  2008年   143篇
  2007年   137篇
  2006年   151篇
  2005年   87篇
  2004年   85篇
  2003年   81篇
  2002年   80篇
  2001年   75篇
  2000年   40篇
  1999年   28篇
  1998年   25篇
  1997年   20篇
  1996年   12篇
  1995年   18篇
  1994年   12篇
  1993年   16篇
  1992年   22篇
  1991年   22篇
  1990年   27篇
  1989年   25篇
  1988年   18篇
  1987年   4篇
  1985年   6篇
  1981年   3篇
  1978年   3篇
  1976年   2篇
  1975年   3篇
  1974年   7篇
  1973年   10篇
  1971年   3篇
  1970年   2篇
  1968年   2篇
  1966年   4篇
  1949年   2篇
  1929年   2篇
排序方式: 共有2445条查询结果,搜索用时 15 毫秒
91.
Objective To determine the extent of the snake bite problem in domestic animals, its regional significance and the effects of antivenom treatment.
Design A questionnaire was designed seeking information on the number and type of domestic animals referred, whether treated or untreated, type of snakes and management of the bite.
Procedure The survey form was sent to 10% of veterinary surgeons, selected at random throughout Australia.
Results The response of 106 veterinary surgeons revealed that snake bite in domestic animals is frequent, with an estimated 6200 cases reported annually. Bites were more prominent in rural (78%) than urban areas (22%) with brown, tiger and black snakes accounting for 76%, 13% and 6% of cases, respectively. Cats and dogs were the most frequently reported victims. Ninety-one percent of cats and 75% of dogs survived following the administration of antivenom whereas 66% of cats and 31% of dogs survived without antivenom. Overall, in 33% of cases antivenom was not used, and venom detection kits were used in only 1% of cases. A number of drugs were used in various combinations with or without antivenom and intravenous fluids in the treatment of animals with snake bite, but their role in reducing the severity of envenomations was not assessed.
Clinical implications Antivenom significantly improves the chances of survival of domestic animals bitten by snakes.  相似文献   
92.
Objective To describe a case of diabetes mellitus in a koala (Phascolarctos cinereus).
Design A case report with controls.
Procedures We describe clinical and laboratory findings in a 6-year-old, free-living, female koala presented with traumatic injury and subsequently found to have polydipsia, hyperglycaemia and glucosuria. Over a 5 week period, serum biochemical analyses, haematological examinations, urinal-yses, measurement of serum insulin and fructosamine concentrations, necropsy, histopathological examination of a range of tissues and immunohistochemical examination of the pancreas for insulin-containing cells were done. For reference purposes, serum insulin and fructosamine concentrations were determined in four and two healthy koalas, respectively, and three healthy koalas pancreases were examined histo-logically and immunohistochemically.
Results The koala had persistent hyperglycaemia, hyperlipidaemia, hyponatraemia, hypochloraemia and glucosuria. Serum insulin concentration of the diabetic koala was only marginally smaller than that of healthy koalas, but all concentrations were smaller than reference concentrations in dogs and people. Fructosamine concentration did not allow the diabetic koala to be distinguished from healthy koalas and concentrations of all koala analytes were greater than expected for healthy dogs and people. Histopathological examination revealed extensive degeneration of pancreatic islet cells and fatty infiltration of hepatocytes. Immunoperoxidase staining revealed decreased or absent insulin in the b cells of the affected koala.
Conclusion Clinical signs, clinicopathological results and histopathological changes were consistent with diabetes mellitus. The pathogenesis of the condition could not be determined but may have been related to the administration of a parenteral corticosteroid preparation, the stress of capture or tissue damage and inflammation.  相似文献   
93.
The occurrence of equine arteritis virus in Australia   总被引:2,自引:0,他引:2  
This paper reports the first isolation of equine arteritis virus (EAV) in Australia and serological evidence of exposure to EAV in Australian horses. Twelve Standardbred stallions imported from North America were found to shed EAV in semen. One hundred and seven stallions were tested for serum antibodies to EAV and 73% of Standardbred stallions tested were seropositive as compared to 8% of Thoroughbred stallions. Serum antibody was detected in 71% of Standardbred mares, 6% of Standardbred racehorses and 1% of Thoroughbred mares and racehorses. Examination of stored serums demonstrated that EAV had been present in Australia since at least 1975.  相似文献   
94.
Forty male, Holstein calves were utilized to evaluate effects of either low (12%) or high (25%) dietary protein on growth and serum metabolites, with a particular concern for serum cholesterol. All diets contained 19% acid detergent fiber and consisted of corn silage, alfalfa hay and grain mixtures. Average concentration of total serum cholesterol was depressed (P = .001) for calves on the high-protein diets (58.8 mg/dl) as compared with their low-protein counterparts (67.9 mg/dl). Calves fed the high-protein diet had lower (P = .002) free serum cholesterol but elevated high-density lipoprotein cholesterol as a percentage of total cholesterol. Calves receiving the high-protein diets showed increases (P = .206) in lecithin cholesterol acyltransferase activity compared with low-protein counterparts. Serum urea nitrogen was increased (P = .001) for calves fed high-protein diets, while serum protein and glucose remained unchanged. Calves fed the high-protein diets consumed less dry matter with improved (P = .09) growth efficiency (gain/feed).  相似文献   
95.
Objective To survey finches in pet shops for Cochlosoma infection and evaluate the efficacy of antiprotozoal therapy with metronidazole or ronidazole.
Design A survey of pet shop finches and drug efficacy trials.
Procedure Finches in pet shops were randomly selected and their faeces examined microscopically for motile Cochlosoma sp trophozoites. Drug trials were carried out on 60 adult finches with naturally occurring infections. Body weight was measured and the faeces of each bird was examined for trophozoites at the beginning and 7 days after the end of treatment. In some birds, additional daily faecal examinations were done until three consecutive negative results were obtained. Metronidazole was administered at various dose rates by crop gavage or in drinking water to eight groups of five to ten finches each. Ronidazole was given in water for 7 days to ten finches. In addition, six finches whose faeces tested positive were necropsied and their tissues collected for histological examination.
Results Motile flagellates in the faeces were identified as C anatis -like protozoa. Red-headed parrot-finches, Bengalese and Lady Gould finches were found to be most commonly infected. Cochlosoma sp was also found in the blue-faced parrot-finch, zebra finch, painted finch, nutmeg mannikin and double-barred finch. Metronidazole and ronidazole were found to be effective against Cochlosoma sp. Histological findings on infected adult finches were normal, except for the presence of numerous flagellates between the colorectal villi and cloacal mucosal folds.
Conclusions Cochlosoma anatis -like organisms can infect several species of finches and in adult finches are confined to the colorectum and cloaca. Infection in adult finches was mostly subclinical and could be treated effectively with metronidazole or ronidazole.  相似文献   
96.
The application of polymer matrix ear tags impregnated with 8.5% w/w cypermethrin to 6 wethers following shearing reduced lice to non-detectable levels on 4 of them at 29 weeks after tagging. At the conclusion of the study at 45 weeks the mean count of lice on tagged wethers was 3 per sheep compared to 158 on untreated wethers. In a second experiment, 6 non-infected sheep were treated at shearing with cypermethrin tags, 6 with 25 g/l cypermethrin backline formulation, 6 with tags plus backline and 6 were left untreated. Each group was exposed to 6 sheep with moderate to heavy infestations of lice. Compared to controls, all treatments delayed infestation, but cypermethrin tags gave no longer protection than backline treatment. All sheep were infested by 17 weeks after commencement of the study. At 45 weeks mean counts of lice were 38, 27, 20 and 74 respectively for sheep treated with tags, backline formulation, backline plus tags and untreated. Possible reasons for the better effect observed from applying tags to infested sheep than to sheep which were not infected at application but which were subsequently exposed to infested sheep are discussed.  相似文献   
97.
Antibacterial and antifungal activity of pinosylvin, a constituent of pine   总被引:1,自引:0,他引:1  
Lee SK  Lee HJ  Min HY  Park EJ  Lee KM  Ahn YH  Cho YJ  Pyee JH 《Fitoterapia》2005,76(2):258-260
The antibacterial and antifungal activities of pinosylvin (3,5-dihydroxy-trans-stilbene), a constituent of pine, were studied and compared with those of resveratrol (3,5,4'-trihydroxy-trans-stilbene). Pinosylvin exhibited more potent growth inhibitory activity against Candida albicans and Saccharomyces cerevisiae.  相似文献   
98.
在已筛选出的代料香菇胶囊菌种专用配方LSC1和LSC5基础上,设计了7种香菇胶囊菌种培养基配方,以L26为供试菌株,观察测试了菌丝生长速度、瘤状突起物形成时间与数量、菌种成型及在愈伤培养时的特征以及菌种持水性等特征指标,筛选出了适宜于工厂化繁育香菇胶囊菌种的专用培养基配方LSCG2T和LSCG3,并在胶囊菌种工厂化繁育生产线中进行了应用试验,取得了良好效果。试验结果表明,工厂化繁育胶囊菌种的配方中粗细木屑的比例应提高到5∶1,配方中应添加以提供微量元素和基质物理性能改良剂的辅料。  相似文献   
99.
The road effect on small rodent population is investigated at 8 fragmented forest areas in the Baekdudaegan moun-tain range, South Korea in September 2001, We especially focused on the distribution and body condition of small rodents near the roads, Korean field mouse (Apodemus peninsulae) seems to be more sensitive to the existence of a road than striped field mouse (Apodemus agradus), Korean field mouse prefers interior forest area to around road. Striped field mouse is a habitat generalist and has wide distributional range around road, but Korean field mouse is forest-inhabiting species and their distribu-tion is limited in forest area. These results suggest the effect of road is different on each small rodent species and their habitat preferences.  相似文献   
100.
In Stenocereus queretaroensis (Weber) Buxbaum, an arborescent cactus cultivated in Jalisco, Mexico, for its fruits but studied here in wild populations, stem extension occurred in the autumn at the beginning of the dry season, flowering and fruiting occurred in the spring at the end of the dry season, and new roots grew in the summer during the wet season. The asynchrony of vegetative and reproductive growth reduces competitive sink effects, which may be advantageous for wild populations growing in infertile rocky soils. Seasonal patterns of sugars in the roots and especially the stems of S. queretaroensis were closely related to the main phenological stages, becoming lower in concentration during periods of major stem extension. Cessation of stem extension occurred in 100-year-old plants for which injection of GA(3) reinitiated such growth. Isolated chlorenchyma cylinders had maximum extension in a bathing solution containing 0.1 &mgr;M gibberellic acid.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号