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   206篇
  免费   0篇
林业   11篇
农学   5篇
  23篇
综合类   41篇
农作物   1篇
水产渔业   19篇
畜牧兽医   97篇
植物保护   9篇
  2018年   2篇
  2012年   3篇
  2011年   2篇
  2010年   8篇
  2009年   2篇
  1998年   5篇
  1997年   7篇
  1996年   5篇
  1995年   7篇
  1994年   1篇
  1993年   8篇
  1992年   2篇
  1991年   8篇
  1990年   14篇
  1989年   6篇
  1988年   4篇
  1987年   6篇
  1986年   5篇
  1985年   3篇
  1984年   3篇
  1983年   2篇
  1982年   7篇
  1981年   1篇
  1980年   3篇
  1979年   2篇
  1978年   2篇
  1977年   3篇
  1976年   4篇
  1975年   2篇
  1974年   3篇
  1972年   2篇
  1971年   1篇
  1970年   1篇
  1968年   2篇
  1966年   1篇
  1963年   3篇
  1962年   2篇
  1961年   3篇
  1960年   1篇
  1959年   1篇
  1958年   11篇
  1957年   7篇
  1956年   7篇
  1955年   5篇
  1954年   6篇
  1953年   8篇
  1951年   1篇
  1950年   1篇
  1948年   4篇
  1946年   3篇
排序方式: 共有206条查询结果,搜索用时 0 毫秒
1.
One hundred seventeen cattle that had undergone surgery were assigned randomly to two preoperative skin preparation protocols. Group 1 (60 animals) skin preparation was with povidone-iodine soap and isopropyl alcohol, whereas group 2 (57 animals) had skin preparation with chlorhexidine gluconate and isopropyl alcohol. Quantitative microbial culture plates were used to estimate the number of colony forming units (CFUs) before skin preparation (prescrub), after skin preparation (postscrub), after surgery (postoperative), and in room air (environment). A significant decrease in CFU occurred postscrub for both skin preparations ( P <.05). Chlorhexidine and alcohol preparation resulted in significantly fewer CFUs (LSMean ± SE = 2.79 CFU ± 1.74) and a greater percentage reduction in CFUs (98.64%± 2.01) postscrub than povidone and alcohol (LSMean ± SE = 10.27 CFUs ± 1.51, 93.29%± 1.85); ( P <.005). Group 2 had a significantly higher frequency of negative cultures postscrub (49.1%) compared with group 1 (18.3%) ( P <.001). The number of postoperative CFUs were not significantly different between the two treatment groups. Wound infection frequency for clean surgical procedures was not significantly different between the two skin preparation protocols (group 1 = 9.8%, group 2 = 10.7%), however, infection frequency was significantly higher for surgical procedures with a ventral abdominal approach (5 of 14, 35.7%), compared with a flank approach (1 of 41, 2.4%) or other approaches (orthopedic procedures) (1 of 16, 6.3%) ( P <.05). Both skin preparation protocols were effective and safe in decreasing the skin microflora population of cattle before surgery and although preparation with chlorhexidine gluconate and alcohol resulted in less CFUs immediafly postscrub, the frequency of surgical wound infection was similar for both protocols.  相似文献   
2.
3.
An 8–year-old castrated male Bassett hound had been vomiting intermittently for 3 weeks. In addition, clinical signs of anorexia, weight loss, dehydration, depression and anterior abdominal pain were noted. Gastro-scopic and radiographic examination revealed a mass at the pyloric region of the stomach. Clinical remission followed surgical excision of gastric carcinoma, with recurrence of vomiting 4 months after surgery. At necropsy, the pyloric region of the stomach was markedly thickened, rigid, scirrhous and had an excavated ulcer. The pathological diagnosis was a poorly differentiated, diffuse gastric carcinoma with metastasis to regional lymph nodes.  相似文献   
4.
5.
Summary. The root and shoot growth of oat (Avena saliva L.) and squash (Cucurbita maxima Duchesne) was reduced in proportion to propachlor concentration. Corn (Zea mays L.) root growth was inhibited only by concentrations of 16 ppm and higher. Cell division in onion (Allium cepa L.) root tips was reduced by propachlor and totally inhibited by 16 ppm. Auxin-induced cell elongation of oat coleoptiles was inhibited in proportion to propachlor concentration. Propachlor treatment prevented the normal senescence of squash cotyledons by inhibiting the autolysis of proteinaceous and lipid reserves. Effets morphologiques, anatomiques et biochimiques du propachlore sur la croissance des plantules Riisumi.  相似文献   
6.
Abstract. The specificity and kinetics of the immune response of rainbow trout ( Salmo gairdneri ) to single injections of an O-antigen extracted from the bacterial pathogen Yersinia ruckeri , which causes enteric redmouth in fish, were investigated by the passive haemolytic plaque assay and serum antibody quantitation. Doses ranging from 5 ng to 500 mg in 10-fold increments were injected intraperitoneally into groups of trout held at 17 × 1°5°C. The occurrence of plaque forming cells (PFC) and humoral antibody was followed for 35 days after injection. Trout gave an immune response to doses of 500 ng and above. Seven days after injection no humoral antibody was detected, but PFC were found in the spleen. The maximum PFC numbers occurred 11 days after injection. On day 21, few PFC were found, whereas serum antibody titres were highest. The antibody from immunized trout showed little or no cross-reactions with sheep red blood cells passively labelled With antigens from other fish pathogens.  相似文献   
7.
Anoestrous dairy cows in seasonally calving herds in the Macalister Irrigation District of Gippsland, Victoria were treated at the start of the mating period with a progesterone releasing intravaginal device (CIDR). The CIDR was inserted for 7 days and 400 IU of PMSG was injected intramuscularly at removal. There was no clinically useful difference among cows receiving the CIDR, a placebo and untreated cows in the interval from treatment to either first oestrus or conception, the conception rate to first service or percent pregnant by the end of mating. Analyses of data from 2-year-old cows, older cattle, cows calved at least 45 days or cows calved at least 55 days and cows treated 3 weeks after the start of mating did not show improved reproductive performance following treatment with the CIDR.  相似文献   
8.
Interference of Sinapis arvensis L. (wild mustard) and Chenopodium album L. (lamb's-quarters) in spring rapeseed (Brassica napus L.) was studied under field conditions in 1983 and 1984. Both weed species interfered with rapeseed early in the growing season, causing significant reductions in rapeseed dry weight by June of each year. Sinapis arvensis caused greater rapeseed grain yield reductions than did C. album. With weed densities of 20–80 plants m?2, rapeseed grain yield reductions ranged from 19 to 77% with S. arvensis but only 20 to 25% with C. album. Rapeseed yield reductions caused by mixtures of both weed species ranged from being less than to being equal to the sum of reductions caused by each weed alone, depending on the weed density and year of study. Both weed species were prolific seed producers capable of returning large quantities of seed to the soil. With weed densities ranging from 10–80 plants m?2, S. arvensis produced 5700–30 100 seeds m?2 while C. album produced 3100–63 600 seeds m?2.  相似文献   
9.
This study examined the digestibilities of whole diets and ingredients of a range of starch/cereal grains when fed to barramundi (Lates calcarifer). The ingredients included wheat, oats, sorghum, triticale, barley, among others. Twelve diets were prepared using a twin‐screw extruder to mimic modern aquafeed‐manufacturing processes. The diets were then fed to juvenile barramundi and the faeces collected using stripping methods. Significant variability in the digestible energy and starch value was seen among the test ingredients and diets. Diet starch digestibility ranged from 49.1% to 93.9%. Ingredient starch digestibility ranged from 18.0% to 96.5%. Among the different starch ingredients, a strong negative correlation between the ingredient amylopectin content and starch digestibility of that ingredient was observed. This relationship was also mirrored by a similar relationship, although not as strong, between total starch and starch digestibility. This study demonstrates that barramundi have limited ability to digest starch and that there is an effect of inclusion level on the ability of the animal to digest this nutrient. But it also demonstrates that there is a wide range of cereal sources that can be effectively used as starch sources in extruded diets for this species.  相似文献   
10.
Abstract. Chinese catfish, Clarias fuscus (Lacepède), within three size ranges were evaluated for growth, survival and feed conversion ratios (FCR). A 4 × 3 factorial design was used during year-long trials which included four temperatures (20,25,30 and 35 °C) and three feeding rates with commercially formulated salmon/trout feed. Specific growth rates of juvenile fish (1–60g) were highest, ranging from 1–64% body weight/day at 20°C (2%/day feed rate), to 4–94%/day at 25°C (6%/day feed rate). Specific growth rates of sub-adult fish (60–150g) averaged 0–65%/day, with no significant difference between temperature-feed rate treatments. Specific growth rates of adult fish (>150g) were lowest, averaging 0–30%/day for grouped feed rate treatments at 25°C, and 0–16%/day at 30°C. Most mortalities occurred during the juvenile stage, with survival ranging from 0% at 35°C(2% feed rate) to 96% at 30°C(6% feed rate). Survival was 95–100% with sub-adults and adults. FCR were 1 to 4 with juveniles, 2 to 12 with sub-adults, and 3 to 22 with adults. These trials suggest that optimal growth and FCRs were obtained at 25°C; with feed rates of 6%/day with juveniles, 2%/day with sub-adults, and 1%/day with adult fish. Final yields at 25 and 30°C indicate that even though growth and FCR are optimal at 25°C, survival was greater at 30°C, which compensated for reduced growth performance at this temperature. Yields at 25 and 30°C were almost double those at 20°C.  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