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   267篇
  免费   15篇
林业   18篇
农学   9篇
基础科学   1篇
  67篇
综合类   29篇
农作物   10篇
水产渔业   23篇
畜牧兽医   99篇
园艺   2篇
植物保护   24篇
  2021年   5篇
  2019年   4篇
  2018年   2篇
  2017年   3篇
  2016年   3篇
  2014年   7篇
  2013年   9篇
  2012年   17篇
  2011年   10篇
  2010年   8篇
  2009年   13篇
  2008年   13篇
  2007年   7篇
  2006年   12篇
  2005年   14篇
  2004年   17篇
  2003年   11篇
  2002年   17篇
  2001年   9篇
  2000年   6篇
  1999年   9篇
  1998年   4篇
  1997年   2篇
  1996年   2篇
  1995年   4篇
  1994年   5篇
  1993年   6篇
  1992年   3篇
  1991年   3篇
  1990年   4篇
  1989年   7篇
  1987年   2篇
  1986年   4篇
  1985年   3篇
  1983年   4篇
  1980年   3篇
  1979年   5篇
  1978年   3篇
  1976年   1篇
  1973年   2篇
  1970年   1篇
  1968年   1篇
  1967年   2篇
  1961年   2篇
  1954年   1篇
  1953年   2篇
  1945年   1篇
  1944年   1篇
  1940年   1篇
  1935年   1篇
排序方式: 共有282条查询结果,搜索用时 406 毫秒
111.
当你漫步在农业展览会的展厅小道时,有时可能会经过一个正在展览不为大多数人所知晓的新产品的展台。今年,在荷兰乌德勒支市的VIV交易会上,Dick Ziggers就惊奇地发现,意大利Silvamicha公司正在展览他们专为牛、猪和禽开发的饲料添加剂--栗树提取物。  相似文献   
112.
Location of the microflora in the skin of cattle   总被引:1,自引:0,他引:1  
  相似文献   
113.
An introduction is provided to the basic ideas and theory of electron-microprobe analysis as applied to biological tissue. The nature of characteristic and continuous X-rays is outlined. X-ray detectors, specimen preparation and the relative advantages and disadvantages of thick and thin section techniques are discussed.  相似文献   
114.
In a series of three replicated and controlled trials, nine dogs artificially infected with Ctenocephalides felis were treated with a systemically active ‘spot-on’ formulation of fenthion, six with a topical spray containing dichlorvos and fenitrothion and six with a surface active ‘spot-on’ preparation containing permethrin, all at recommended dose rates. Good knockdown efficacy was apparent at eight hours with the dichlorvos/fenitrothion combination and at 24 hours with the other formulations. Efficacy values in excess of 95 per cent persisted for at least 22 days in the case of the systemic fenthion preparation and the permethrin product and eight days for the dichlorvos and fenitrothion combination. Twenty-nine days after treatment there was still substantial protection in the fenthion- and permethrin-treated animals, indicated by an 88 and a 77 per cent reduction in flea counts in the two groups, respectively.  相似文献   
115.
A controlled study was carried out in two replicated trials, each using three groups of domestic cats artificially infested with Ctenocephalides felis. In each trial three cats were treated with fenthion, three were treated with a dichlorvos/fenitrothion formulation, both at the recommended dose rate and the remainder acted as untreated controls. Good knockdown efficacy was evident 24 hours after both treatments. Efficacy values of 85 per cent or more were maintained for at least 15 days with fenthion and for less than eight days with dichlorvos/fenitrothion.  相似文献   
116.
117.
We developed a canine model for autologous bone marrow transplantation (AuBMT) with long-term marrow culture (LTMC) cells. Marrow was harvested from nine normal dogs. Harvests from dogs 2-7 were placed into 21 day LTMC. Cells in LTMC from dogs 4-7 were labelled with the neomycin phosphotransferase gene neo. Dogs were given 60Co total body irradiation (TBI) and then infused with LTMC cells: dog 1 received 500 cGy TBI and 2.08 x 10(8)/kg uncultured marrow cells. Dogs 2-7 received 600-800 cGy TBI and 0.07-0.45 x 10(8)/kg LTMC cells. Dogs 8 and 9 received 600 and 800 cGy TBI, respectively, but no infusion of marrow or LTMC cells. For all dogs, profound myelosuppression developed during week 1 and pyrexia developed during week 2. Enrofloxacin was given from one day before TBI until a peripheral neutrophil count > 1.0 x 10(9)/L was achieved, which eliminated Escherichia coli from feces. Dogs 1, 2 and 5-9 also received gentamicin and/or combination beta-lactam antibiotics. Numerous platelet transfusions were needed to control hemorrhages in all dogs except dog 1. Dog 1 achieved neutrophils > 1.0 x 10(9)/L on day 15, while dogs 2 and 5-9 achieved this count on days 33-48. Dogs 3 and 4 died on days 17 and 18, respectively, of beta-hemolytic streptococcal sepsis and hemorrhage, with no evidence of hematopoiesis at necropsy. The marker gene, neo, was documented in lymphoid and myeloid cells of dogs 5-7 up to 21 months post-AuBMT. Our studies indicate that dogs can recover following supralethal TBI and can survive the delayed engraftment associated with AuBMT using LTMC cells, if they receive intensive platelet and antimicrobial therapy. Used prophylactically for such therapy, enrofloxacin achieved selective intestinal decontamination, but did not prevent sepsis when used as the sole antimicrobial agent during myelosuppression. Furthermore, our studies indicate that infused LTMC cells, at the above doses, can contribute to hematopoietic recovery, but are not essential for recovery following TBI, and do not shorten the period of prolonged profound myelosuppression induced by TBI.  相似文献   
118.
Clipping and shaving remove cell and lipid layers from the stratum corneum and also modify the effects of subsequent lipid collection and microbiological sampling techniques. The damage to the epidermis caused by solvents indicates that further evaluation of some sebum collection procedures and of the effects of dips and dressings applied to the skin is required.  相似文献   
119.
An immunohistochemical technique was developed for detection of feline calicivirus (FCV) in formalin-fixed, paraffin-embedded cultured cells and tissues. Initial trials with cultured cells indicated that the indirect immunoperoxidase method using rabbit antiserum to FCV strain 255, and horseradish peroxidase-labelled antibodies to rabbit immunoglobulin G lacked sensitivity and showed excessive diffuse background staining despite trypsin digestion of sections before staining. An amplified indirect immunoperoxidase technique using commercially available biotinylated antirabbit antibodies and avidin-biotin-peroxidase or streptavidin-peroxidase (SP) complexes proved highly successful. When optimal conditions, including those for trypsinization, inactivation of endogenous peroxidase and blocking were determined, the SP technique was preferred. Applied to tissue of cats in the acute phase of FCV infection, the technique provided clear identification of cells containing FCV antigens in sections in which histological detail was well preserved.  相似文献   
120.
OBJECTIVES: To determine the effects of oral administration of tilmicosin in piglets experimentally infected with Actinobacillus pleuropneumoniae. ANIMALS: Forty 3-week-old specific-pathogen free piglets. PROCEDURES: Piglets were assigned to 1 of 4 groups as follows: 1) uninfected sham-treated control piglets; 2) infected untreated piglets that were intratracheally inoculated with 10(7) CFUs of A pleuropneumoniae; 3) infected treated piglets that were intratracheally inoculated with A pleuropneumoniae and received tilmicosin in feed (400 ppm [microg/g]) for 7 days prior to inoculation; or 4) infected treated piglets that were intratracheally inoculated with A pleuropneumoniae and received chlortetracycline (CTC) in feed (1100 ppm [microg/gl) for 7 days prior to inoculation. Bronchoalveolar lavage (BAL) fluid and lung tissue specimens of piglets for each group were evaluated at 3 or 24 hours after inoculation. For each time point, 4 to 6 piglets/group were studied. RESULTS: Feeding of CTC and tilmicosin decreased bacterial load in lungs of infected piglets. Tilmicosin delivered in feed, but not CTC, enhanced apoptosis in porcine BAL fluid leukocytes. This was associated with a decrease in LTB4 concentrations in BAL fluid of tilmicosin-treated piglets, compared with untreated and CTC-treated piglets, and also with a significant decrease in the number of pulmonary lesions. Tilmicosin inhibited infection-induced increases in rectal temperatures, as measured in untreated and CTC-treated piglets. Pulmonary neutrophil infiltration and prostaglandin E2 concentrations in the BAL fluid were not significantly different among groups at any time. CONCLUSIONS AND CLINICAL RELEVANCE: Oral administration of tilmicosin to infected piglets induces apoptosis in BAL fluid leukocytes and decreases BAL fluid LTB4 concentrations and inflammatory lung lesions.  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