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   156篇
  免费   3篇
农学   1篇
  9篇
综合类   14篇
农作物   5篇
水产渔业   23篇
畜牧兽医   97篇
植物保护   10篇
  2021年   1篇
  2019年   2篇
  2018年   1篇
  2016年   1篇
  2015年   1篇
  2013年   2篇
  2012年   1篇
  2010年   2篇
  2009年   5篇
  2008年   3篇
  2007年   1篇
  2005年   2篇
  2003年   4篇
  2002年   7篇
  2001年   1篇
  1999年   1篇
  1998年   10篇
  1997年   4篇
  1996年   10篇
  1995年   1篇
  1994年   6篇
  1993年   5篇
  1992年   8篇
  1991年   7篇
  1990年   8篇
  1989年   6篇
  1988年   9篇
  1987年   6篇
  1986年   7篇
  1985年   4篇
  1984年   5篇
  1983年   6篇
  1981年   2篇
  1980年   2篇
  1979年   2篇
  1978年   1篇
  1976年   1篇
  1975年   3篇
  1971年   1篇
  1968年   1篇
  1958年   2篇
  1957年   2篇
  1954年   2篇
  1953年   1篇
  1952年   1篇
  1947年   1篇
排序方式: 共有159条查询结果,搜索用时 218 毫秒
71.
Fifty dairy goats, of various ages, sexes and breeds were selected for examination on the basis of positive serological reactions to caprine arthritis-encephalitis virus (CAEV). Thirty-one had lung lesions including chronic interstitial pneumonia of caudal or cranioventral lobes, bronchopneumonia, verminous pneumonia, pulmonary cryptococcosis or combinations of these. The only infective agent recovered from all the chronic interstitial pneumonia cases examined was CAEV, which was also recovered from lung tissue of 3 goats with arthritis but no lung lesions. The presence of CAEV in lavaged alveolar macrophages from normal lung tissue and from lungs affected with chronic interstitial pneumonia and verminous pneumonia, and the demonstration of a marked increase in nonspecific esterase staining macrophages in areas of chronic interstitial pneumonia, are discussed in relation to the aetiology of the pneumonia.  相似文献   
72.
73.
An unusual outbreak of contagious ovine ecthyma   总被引:1,自引:0,他引:1  
  相似文献   
74.
The development of specific enzyme-linked immunosorbent assays (ELISA) for antibody to types C and D Clostridium botulinum toxins for investigation of botulism in cattle is described. Partially purified type C and D toxins were used as antigens to develop these ELISAs. Specificity of the ELISAs was evaluated on sera from 333 adult beef and dairy cattle from areas with no history or evidence of botulism in animals or water birds. The test was also evaluated on sera from 41 herds that included herds vaccinated against botulism, confirmed botulism cases and herds from areas where the disease is considered endemic. The ELISAs detected the presence of antibody to botulinum toxins in samples from vaccinated cattle and both convalescent and clinically normal animals from unvaccinated herds with outbreaks of botulism. Antibody was also found in unvaccinated animals from herds in which there had been no diagnosed botulism cases in areas where botulism was considered endemic. Sera from some unvaccinated cattle with high ELISA reactivity was shown to be protective for mice in botulinum toxin neutralisation tests. The use of these tests in investigations of botulism in cattle is discussed.  相似文献   
75.
76.
Many cats do not receive analgesics for treatment of perioperative pain, but when they do, the opioid agonist–antagonist butorphanol (B) is widely used. B is reported to provide long‐lasting visceral analgesia, but its somatic actions are not well documented. This study aimed to assess B by using a thermal threshold (TT) model. Six cats (four spayed females, two castrated males, 4.4–6.9 kg) participated in the study. The day before each study, the lateral thorax of each of the cats was shaved and a cephalic catheter was placed. TT was measured using a thermal threshold testing device specifically developed for cats. A heater element and temperature sensor housed in a small probe was held against the cat's thorax with an elastic band and pressure bladder to assure consistent contact. Skin temperature was recorded before each test, then the heater was activated. When the cat responded by flinching, turning, or jumping, the stimulus was terminated and the threshold temperature recorded. A cut‐out temperature was set at 55.5 °C. Three baseline measurements were recorded before IV injections of 0.1, 0.2, 0.4, or 0.8 mg kg?1 of B. Each cat received all doses in a randomized order at least 1 week apart, and the investigator was blinded to the treatments. TT was measured at every 15 minutes for 6 hours. Data were analyzed using a three‐factor anova , and the critical mean difference was calculated. Pre‐treatment threshold was 40.8 ± 2.25 °C in all cats. There was a significant increase in threshold in all groups from 15 to 90 minutes, but no dose‐related differences were observed. Peak threshold achieved was 48.35 °C, 60 minutes after 0.4 mg kg?1 of B was injected. Mydriasis was present in all cats after treatment, and many exhibited dysphoric behavior. In this model, B had a short duration of action and no dose–response relationship. Compared to other opioids tested under similar conditions, the intensity of the effect of B was small and of shorter duration.  相似文献   
77.
78.
Abstract. Aeromonas salmonicida produces many extracellular enzymes, some of which are known to play an important role in pathogenesis and virulence, while the role of others is presently speculative. The latter group includes amylase, aryl-sulphatase, glucosidases, esterases and lysophospholipase. There are two enzymes which are known to be of prime importance in pathogenesis: a 70-kDa protease (caseinase) and a 25-kDa phospholipase (glycerophospholipid: cholesterol acyltransferase, GCAT). The protease causes extensive tissue liquefaction, activates the blood clotting system and is lethal for fish at 2·4 μg/g fish. It is inhibited by α2-macroglobulin but resistant to all the other serum protease inhibitors. Its role in vivo appears to be as a broad spectrum protease providing amino acids for in vivo growth. The GCAT is mainly present in a high molecular weight complex with LPS. The complex is extremely haemolytic for fish (but not mammalian) erythrocytes. It is the most lethal component of the exotoxins (lethal dose 45 ng/g fish). The complex with LPS confers enhanced toxicity to the GCAT and stability to heat and proteolytic degradation. In vitro , this toxin also has high leucocytolytic and cytolytic (RTG-2) activity. On injection into fish, it causes very little histopathology other than a marked degranulation of eosinophilic granular cells (EGCs) in the gills. Its precise mode of pathogenesis is uncertain and appears complex. The protease and the GCAT/LPS have an additive relationship in respect to lethal doses and mixtures of the two produce extensive liquefactive and haemorrhagic lesions typical of furuncles. The possible relationship of the GCAT/LPS to other less well characterized factors (cytotoxin, leucocytolysin, haemolysin, salmolysin) is discussed.  相似文献   
79.
80.
Abstract The role of A-layer (A), protease (P) and haemolysin (H) as virulence factors of Aeromonas salmonicida, the aetiological agent of fish furunculosis, was a investigated using three strains of the bacterium. Strain MT004 lacked the A-Iayer (A) and produced extracellular caseinase and gelatinase (P+) and haemolysin (T-lysin; H+). Strain MT028 was A, P and H, and strain MT048 was A+, P+ and H. The pathology and LD50 produced in rainbow trout by cells or extracellular products (ECP) of each strain were determined. The ECP was produced by two different methods where the protease and haemolytic activities differed in relative levels, or when the protease of MT004 ECP was inhibited by the serine protease inhibitor PMSF. The results indicate that the presence of A-layer is not essential, at least for a moderate degree of virulence; that in vitro production of extracellular proteases is not a requisite of virulent strains; that presence of protease and haemolysin in ECP can be correlated with the development of certain lesions and a rapid time to death but cannot be correlated with the lethal toxicity of the ECP. The authors conclude that an as-yet unrecognized component of ECP is responsible for killing fish.  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