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   74篇
  免费   1篇
林业   2篇
  4篇
综合类   15篇
农作物   1篇
水产渔业   2篇
畜牧兽医   46篇
园艺   2篇
植物保护   3篇
  2019年   2篇
  2018年   1篇
  2016年   1篇
  2013年   1篇
  2012年   2篇
  2011年   2篇
  2008年   4篇
  2007年   4篇
  2005年   5篇
  2004年   4篇
  2003年   3篇
  2002年   1篇
  2001年   2篇
  1997年   1篇
  1992年   3篇
  1991年   4篇
  1990年   4篇
  1989年   4篇
  1988年   2篇
  1985年   2篇
  1984年   6篇
  1982年   1篇
  1980年   3篇
  1978年   1篇
  1975年   1篇
  1971年   1篇
  1967年   1篇
  1964年   1篇
  1944年   2篇
  1943年   2篇
  1938年   1篇
  1927年   1篇
  1920年   1篇
  1909年   1篇
排序方式: 共有75条查询结果,搜索用时 0 毫秒
41.
42.
Nuclear estrogen receptor from MCF-7 cells undergoes a time-dependent, hormone-inducible transformation to a form that is less extractable from nuclei and less exchangeable with ligand. This receptor-modifying, intranuclear event is independent of receptor loss (processing) and appears associated with hormone responsiveness (progesterone-receptor induction) in these cells. The magnitude of receptor loss, however, is variable and apparently not a prerequisite for hormone action to induce progesterone receptor.  相似文献   
43.
Summary

A data resampling method to test signi®cance of alternate bearing against a null hypothesis of random independent variation is described and discussed.  相似文献   
44.
Hydrated sodium calcium aluminosilicate (HSCAS), an anticaking agent for mixed feed, was added to the diets of growing wethers (mean body weight, 34.0 kg) and was evaluated for its ability to diminish the clinical signs of aflatoxicosis. The experimental design consisted of 4 treatment groups of 5 wethers each, consuming concentrations of 0 g of HSCAS and 0 g of aflatoxin (AF)/kg of feed (control; group 1); 20 g of HSCAS/kg (2.0%; group 2), 2.6 mg of AF/kg (group 3); or 20 g of HSCAS (2.0%) plus 2.6 mg of AF/kg (group 4). Wethers were maintained in indoor pens, with feed and water available ad libitum for 42 days. Lambs were observed twice daily and weighed weekly, and blood samples were obtained every 2 weeks for hematologic and serum biochemical analyses and for measurement of mitogen-induced lymphocyte-stimulation index. At the termination of the study, wethers were euthanatized and necropsied. Body weight gain was diminished significantly (P less than 0.05) by consumption of 2.6 mg of AF/kg of feed, whereas body weight of lambs consuming HSCAS plus AF did not differ from that of control wethers. The AF-alone treatment increased serum aspartate transaminase and gamma-glutamyltransferase activities, prothrombin time, and cholesterol, uric acid, and triglyceride values and decreased albumin, glucose, and urea nitrogen values, and urea-to-creatine ratio.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
45.
(Z)-cis- and (Z)-trans-3-(2-chloro-3,3,3-trifluoroprop-1-enyl)-2,2-dimethylcyclo-propanecarboxylic acids react with bromine under radical conditions predominantly to open the cyclopropane ring; the stereochemistry and reactions of the dibromides thus formed are described.  相似文献   
46.
A bacteriophage to a serotype 02, nonmotile Escherichia coli was isolated from municipal waste treatment facilities and poultry processing plants. A study was conducted to determine the efficacy of multiple vs. single intramuscular (i.m.) injections of bacteriophage to treat a severe E. coli respiratory infection. The birds were challenged at 7 days of age by injection of 6 x 10(4) colony-forming units (cfu) of E. coli into the thoracic air sac followed by an i.m. injection into the thigh with either heat-killed or active bacteriophage. There were 16 treatments with three replicate pens of 10 birds. There were four control treatments, which included untreated birds, birds injected with either heat-killed or active bacteriophage, and birds challenged only with E. coli. In the remaining treatments, birds were injected with heat-killed or active bacteriophage either once immediately after E. coli challenge or immediately after challenge and at 8 and 9 days of age, once at 8 days of age or at 8, 9, and 10 days of age, and once at 9 days of age or at 9, 10, and 11 days of age. Mortality was significantly decreased from 57% to 13% in the birds given a single i.m. injection of bacteriophage immediately after E. coli challenge, and there was complete recovery in birds treated immediately after challenge and at 8 and 9 days of age, which was a significant improvement from the single injection treatment. There was a significant reduction in mortality from 57% to 10% in the birds treated with bacteriophage once at 8 days of age and those birds treated at 8, 9, and 10 days of age, with no difference between single or multiple treatments. The mortality in the single or multiple phage treated birds that started at 9 days of age was reduced from 57% to 28% and 27%, respectively, but was not statistically different from the control. These data suggest that bacteriophage can be an effective treatment when administered early in this experimental E. coli respiratory disease and that early multiple treatments are better than a single treatment. The efficacy of bacteriophage treatment diminishes as it is delayed, with no difference between single or multiple treatments. Bacteriophage may provide an effective alternative to antibiotics, but like and biotic therapy, the effectiveness of phage to rescue animals decreases the longer treatment is delayed in the disease process.  相似文献   
47.
A competitive enzyme immunoassay was developed to measure the changes in serum levels of ovotransferrin (OTF) during inflammation and infectious diseases in chickens. The assay is based on the competition of serum OTF with a fixed concentration of biotin-labeled OTF to bind to a rabbit anti-chicken transferrin antibody immobilized on microtiter wells. After several washing steps, the antibody-bound biotinylated OTF is probed with streptavidin-horseradish peroxidase conjugate (HRP) followed by a colorimetric detection of the HRP activity. The relative changes in the optical density of color are plotted against the competing concentrations of OTF with logarithmic regression to generate a standard curve that is used to determine the concentrations of OTF in unknown samples. Serum had no effect on the measurement of OTE By this method, the time course changes of serum OTF levels in 4-wk-old male broiler chickens that were subjected to inflammation by croton oil injection were measured. The results showed croton oil-induced inflammation elevated serum OTF levels at 16 hr postinjection. OTF levels reached a peak by 72 hr, remained high through 120 hr, and returned to a basal level of olive oil-injected controls by 240 hr. There were no changes in serum OTF levels at any of the above time points in olive oil-injected control chickens. For studies with poultry diseases, specific-pathogen-free (SPF) male chickens were challenged with known bacterial and viral pathogens, and serum was collected at the height of the infection, i.e., 7 days after the challenge. Compared with uninjected controls, the SPF chickens challenged with Escherichia coli, fowl poxvirus, respiratory enteric orphan virus, infectious bursal disease virus, infectious bronchitis virus, or infectious laryngotracheitis virus had higher levels of OTF in serum. Inflammation-induced changes in serum OTF levels were also evident in the changes in the density of a 65-kD band protein corresponding to OTF. These results demonstrate that serum OTF may be a nonspecific clinical marker of inflammation associated with traumatic or infectious avian diseases.  相似文献   
48.
Immersing grapefruit in vegetable oils and vegetable oil—water emulsions prior to storage at 3°C markedly delayed and reduced symptoms of chilling injury. Oil—water emulsions of 20% oil were more effective than higher percentage oil emulsions or 100% oil.  相似文献   
49.
50.
1. The effects of high fat diets and prednisolone treatment were studied to understand the etiology of femoral head separation (FHS) in fast growing broiler chickens. Dietary effects on production parameters such as growth, feed conversion ratio (FCR) and blood chemistry were also measured.

2. Three groups of chickens, consisting of 30 birds each, in two replicate pens, were fed isonitrogenous diets containing 40 (control), 60, or 80?g poultry fat supplements per kg feed. The birds were fed a starter diet containing the fat supplements for the first three weeks, then switched to a grower diet containing the same supplements for the rest of the experimental period. Two groups of birds were also raised with the control diets, but were administered either cholesterol or prednisolone intramuscularly at 30 and 32 days of age to evaluate their effects on FHS incidences.

3. The chickens were euthanised and necropsied at 37?d of age. The presence of femoral head weakness was determined by applying mild pressure on the pelvic joint to cause the growth plate to become detached from its articular cartilage in affected cases.

4. High fat diets did not change FHS incidences, but increased 28?d body weights (BW) and FCR. At 37?d of age the BW differences were not significant but the FCR (gain: feed ratio) remained higher in high fat fed groups. Prednisolone treatment, by contrast, resulted in decreased BW, decreased feed efficiency, increased FHS index, and elevated blood lipid levels.

5. The results suggest that high dietary fats do not affect FHS incidence in broilers. Prednisolone treatment causes hyperlipidaemia and increases FHS index, and may therefore provide a suitable experimental model of FHS pathogenesis in growing chickens.  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