全文获取类型
收费全文 | 18103篇 |
免费 | 124篇 |
国内免费 | 3篇 |
专业分类
林业 | 3718篇 |
农学 | 1340篇 |
基础科学 | 142篇 |
3092篇 | |
综合类 | 892篇 |
农作物 | 2154篇 |
水产渔业 | 2028篇 |
畜牧兽医 | 1695篇 |
园艺 | 1162篇 |
植物保护 | 2007篇 |
出版年
2024年 | 8篇 |
2023年 | 11篇 |
2022年 | 16篇 |
2021年 | 33篇 |
2020年 | 43篇 |
2019年 | 54篇 |
2018年 | 2777篇 |
2017年 | 2742篇 |
2016年 | 1236篇 |
2015年 | 125篇 |
2014年 | 59篇 |
2013年 | 112篇 |
2012年 | 888篇 |
2011年 | 2227篇 |
2010年 | 2180篇 |
2009年 | 1327篇 |
2008年 | 1406篇 |
2007年 | 1669篇 |
2006年 | 124篇 |
2005年 | 179篇 |
2004年 | 181篇 |
2003年 | 246篇 |
2002年 | 116篇 |
2001年 | 36篇 |
2000年 | 67篇 |
1999年 | 20篇 |
1998年 | 13篇 |
1997年 | 16篇 |
1995年 | 10篇 |
1994年 | 7篇 |
1993年 | 23篇 |
1992年 | 18篇 |
1991年 | 16篇 |
1990年 | 13篇 |
1989年 | 17篇 |
1988年 | 19篇 |
1987年 | 11篇 |
1985年 | 13篇 |
1984年 | 15篇 |
1983年 | 13篇 |
1982年 | 7篇 |
1981年 | 9篇 |
1979年 | 10篇 |
1977年 | 12篇 |
1975年 | 7篇 |
1974年 | 11篇 |
1973年 | 7篇 |
1971年 | 6篇 |
1969年 | 6篇 |
1968年 | 11篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
41.
42.
Holbrook TC Munday JS Brown CA Glover B Schlievert PM Sanchez S 《Journal of the American Veterinary Medical Association》2003,222(5):620-3, 601-2
A 3-year-old Thoroughbred gelding was examined because of clinical signs of pneumonia and shock. Mucous membrane petechiation and ventral edema were observed and considered to be a result of vasculitis. Epidermal necrosis developed on the distal portions of the limbs. The horse had a persistent high fever that was unresponsive to nonsteroidal anti-inflammatory treatment, and Staphylococcus aureus was isolated from a nasal swab specimen and 2 transtracheal wash fluid samples. Antimicrobial, anti-inflammatory, and supportive treatment resulted in clinical improvement. However, resolution of the pulmonary infection required long-term (42 days) antimicrobial administration. Staphylococcus aureus strains isolated from this horse were positive for the toxic shock syndrome toxin-1 gene and were shown to produce toxic shock syndrome toxin-1, the causative factor in toxic shock syndrome in humans. The horse's clinical signs were attributed to toxic shock syndrome secondary to pulmonary S. aureus infection. 相似文献
43.
Twomey DF Griffiths PC Horigan MW Hignett BC Martin TP 《Veterinary journal (London, England : 1997)》2006,171(3):574-576
An outbreak of upper respiratory tract disease was investigated in a group of 17 housed home-bred calves on a mixed dairy, beef and sheep farm in Devon. Conjunctival swabs were collected and tested for Chlamydophila spp. DNA using a PCR test that detects Chlamydophila abortus and Chlamydophila psittaci. Six of the calves tested gave a positive result. Further epidemiological observations and laboratory testing indicated that the adult dairy cows, from which the affected calves originated, were the most likely source of infection. 相似文献
44.
45.
Rui A. Gonçalves Tu Do Cam Nguyen Nhu Tri Gonçalo A. Santos Pedro Encarnação Le Thanh Hung 《Aquaculture International》2018,26(3):921-936
Triplicate groups of one hundred Tra catfish (8 g?±?0.2) were fed seven test diets containing increasing levels of AFB1 (0, 50, 100, 250, 500, and 1000 μg AFB1 kg?1). Additionally Mycofix® Secure was added at 1.5% to one diet containing 500 μg AFB1 kg?1. Results showed that Tra catfish are sensitive to AFB1. Reduction in weight gain (P?<?0.05) was observed for fish fed 50 μg AFB1 kg?1 and declined further with increasing levels of AFB1 in the diets. Fish fed diets contaminated with 500 and 1000 μg AFB1 kg?1 showed increased (P?>?0.05) hepatosomatic index (HIS), while an increase in adipose somatic index (ASI) was observed in fish fed 50 μg AFB1 kg?1 and above when compared to the control and Mycofix® diets. After 12 weeks, blood serum analysis revealed higher alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels in fish fed the 50, 100, and 250 μg AFB1 kg?1 suggesting occurrence of liver damage. Disease resistance of fish exposed to Edwardsiella ictaluri was also compromised by the presence of AFB1 in the feed and was directly related to the contamination level. Seven days after Edwardsiella ictaluri exposure, survival rates were 50, 41.7, 31.7, and 8.3% for fish fed control, 50, 100, and 250 μg AFB1 kg?1, respectively. This trial shows that AFB1 at a level of 50 μg AFB1 kg?1 and above can affect fish performance and disease resistance. Application of an effective mycotoxin management in the feed seems to be useful to prevent the negative effects of AFB1. 相似文献
46.
47.
Shiilegdamba E Carpenter TE Perez AM Thurmond MC 《Veterinary research communications》2008,32(3):201-207
Prior to 2000, foot-and-mouth disease (FMD) had not been observed in Mongolia since 1973; however, between April 2000 and
July 2002, Mongolia reported 44 FMD outbreaks that affected cattle, sheep, goats, and camels. The objectives of this study
were to describe the distributions of the 44 reported FMD outbreaks in Mongolia and to assess their spatial clustering and
directions of movement. Official reports were collected to obtain the number and species of animals both affected and at risk,
and the date and geographical coordinates of each outbreak. Significant global and local spatial clusters of reported FMD
outbreaks were identified. Disease spread during the second epidemic moved 76° northeast and the spread of the disease during
the third epidemic moved 110° northwest. FMD outbreaks were clustered intensely close to other FMD-positive counties. These
findings can be used in the future to help plan prevention and control measures in high risk areas. 相似文献
48.
49.
Stuart P. Hardegree Corey A. Moffet Gerald N. Flerchinger Jaepil Cho Bruce A. Roundy Thomas A. Jones Jeremy J. James Patrick E. Clark Frederick B. Pierson 《Strength and Conditioning Journal》2013,66(2):127-135
The microclimatic requirements for successful seedling establishment are much more restrictive than those required for adult plant survival. The purpose of the current study was to use hydrothermal germination models and a soil energy and water flux model to evaluate intra- and interannual variability in seedbed microclimate relative to potential germination response of six perennial grasses and cheatgrass. We used a 44-yr weather record to parameterize a seedbed microclimate model for estimation of hourly temperature and moisture at seeding depth for a sandy loam soil type at the Orchard Field Test Site in southwestern Ada County, Idaho. Hydrothermal germination response was measured in the laboratory for two seed lots of cheatgrass (Bromus tectorum L.), four seed lots of bluebunch wheatgrass (Pseudoroegneria spicata [Pursh] Löve), three seed lots of bottlebrush squirreltail (Elymus elymoides [Raf] Swezey), and one seed lot each of Sandberg bluegrass (Poa secunda J. Presl.), big squirreltail (Elymus multisetus [J.G. Smith] M.E. Jones), thickspike wheatgrass (Elymus lanceolatus [Scribn. And J.G. Smith] Gould) and Idaho fescue (Festuca idahoensis Elmer). Germination response models were developed to estimate potential germination rate for 13 subpopulations of each seed lot for every hour of the 44-yr simulation. Seedbed microclimate was assessed seasonally and for each day, month, and year, and germination rate-sum estimates integrated for a numerical index of relative site favorability for germination for each time period. The rate-sum favorability index showed a consistent pattern among seed lots for different years, and provides a relatively sensitive indicator of annual and seasonal variability in seedbed microclimate. This index could be used with field data to define minimum weather thresholds for successful establishment of alternative plant materials, in conjunction with weather forecast models for making restoration and fire-rehabilitation management decisions in the fall season, for evaluation of potential climate-change impacts on plant community trajectories, and in optimization schemes for selecting among alternative restoration/rehabilitation management scenarios. 相似文献
50.
Cooper RG 《Tropical animal health and production》2007,39(6):439-442
Data from post-mortem and field studies were obtained that discussed poisoning in ostriches following ingestion of toxic plants.
From the notes, all plants studied caused death in ostriches and there was systemic organ damage. Poisoning from Sarcostemma viminale (Melktou) resulted in beak patting, muscular tremors and head flopping, followed by collapse and violent kicking before death.
Ingestion of Combretum oatesii (Red wings) seeds from plants in free grazing pastures resulted in vomiting, restlessness, eyelid flicking, collapse and
kicking movements. Dichapetalum cymosum (Gifblaar) killed an ostrich after episodes of shaking legs, rapid respiration and bradycardia and hyperaemia of the lungs,
liver and kidneys. Poisoning from Senecio sceleratus (Ragwort) caused skin haemorrhages and bleeding in tracheal mucous membranes, the pericardium, diaphragm and interperitoneal
membrane. Consumption of drupes from Melia azedarach (Syringa berry) caused muscle tremors, kicking movements and respiratory distress. Lantana camara (Cherry pie) poisoning resulted in extremely inflamed eyes with copious yellow exudates extending down their beaks and onto
their necks. Bentonite was administered by gavage at a dose of 5 g/kg. Poisoning in these cases is usually associated with
the farmer allowing his/her birds to roam free-range in paddocks in which toxic plants are growing. Toxic plants should be
removed from grass cut for hay.
The author is willing to send photographs of all poisonous plants if requested by a reader. 相似文献