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   160篇
  免费   19篇
农学   1篇
基础科学   1篇
  15篇
综合类   30篇
农作物   1篇
水产渔业   1篇
畜牧兽医   121篇
园艺   2篇
植物保护   7篇
  2020年   5篇
  2019年   3篇
  2018年   6篇
  2017年   5篇
  2016年   11篇
  2015年   3篇
  2014年   3篇
  2013年   10篇
  2012年   7篇
  2011年   4篇
  2010年   5篇
  2009年   3篇
  2008年   2篇
  2007年   3篇
  2006年   6篇
  2005年   6篇
  2004年   2篇
  2003年   4篇
  2002年   3篇
  2001年   3篇
  2000年   4篇
  1999年   4篇
  1997年   7篇
  1996年   7篇
  1995年   3篇
  1994年   3篇
  1993年   4篇
  1992年   4篇
  1991年   3篇
  1990年   6篇
  1989年   6篇
  1988年   3篇
  1987年   2篇
  1986年   1篇
  1985年   2篇
  1983年   1篇
  1982年   2篇
  1981年   2篇
  1980年   1篇
  1974年   1篇
  1971年   2篇
  1969年   1篇
  1967年   2篇
  1965年   2篇
  1938年   1篇
  1936年   2篇
  1929年   1篇
  1921年   2篇
  1914年   1篇
  1913年   1篇
排序方式: 共有179条查询结果,搜索用时 15 毫秒
161.
This study was conducted to determine the impact of dried distiller's grain with solubles (DDGS) from 192 days of gestation through 118 days of lactation on feedlot performance, carcass characteristics, Longissimus muscle (LM) fatty acids and glucose tolerance of male progeny (n = 36). Angus‐Simmental heifer dams were fed diets that contained either DDGS (DG) or not (CON) formulated to provide similar daily net energy for gain but differing crude protein. In the feedlot, male progeny were fed a diet devoid of DDGS. An intravenous glucose tolerance test (IVGTT) was performed on a subset of 20 steers prior to harvest. Steers were harvested at a common 12th rib fat depth. Data were analyzed with the GLIMMIX and MIXED procedures of SAS. Performance (P ≥ 0.11) and glucose and insulin concentrations during IVGTT (P ≥ 0.24) did not differ between treatments. Dressing percentage tended to be greater (P = 0.09) in DG than CON progeny, but all other carcass characteristics did not differ (P ≥ 0.18). Progeny from DG dams had greater LM 16:2, 18:0, and 20:1 n‐9 concentrations than progeny from CON dams (P ≤ 0.02). In conclusion, DDGS are a viable option for gestating and lactating beef cows.  相似文献   
162.
163.
Chronic hypertrophic pyloric gastropathy in 14 dogs   总被引:1,自引:0,他引:1  
SUMMARY Ten mate and 4 female dogs with chronic hypertrophic pyloric gastropathy were seen at the Sydney University Veterinary Teaching Hospital in the period 1982–88. The most commonly affected breeds were the Shihtzu and Maltese. The mean age was 8.2 yr and the mean body weight 6.5 kg. The most common clinical signs were vomiting, weight loss, polydipsia and depression. Hypokalaemia was present in 11 of 12 dogs examined and hypochloraemia in 10 of 11 dogs examined. Five of the six dogs that had blood gases measured were found to have a metabolic alkalosis. Surgery was performed on 13 dogs; pyloromyotomy 7, pyloroplasty 4, gastroduodenostomy 2. There was a recurrence of symptoms in one pyloromyotomy dog, and fatal ulceration and perforation of the cardia occurred in one pyloroplasty case. The remaining 11 dogs had a mean known symptom-free survival time of 20 mo. This study confirms the preponderance of affected males, identifies electrolyte and blood gas disturbances as significant complications of chronic hypertrophic pyloric gastropathy, and suggests that relatively minor surgery (pyloromyotomy) may have a place in the treatment of a selected subgroup of cases.  相似文献   
164.
165.
The effect of dietary energy restriction on serum insulin, insulin-like growth factor I (IGF-I), growth hormone, (GH), cortisol, plasma urea nitrogen (PUN) and nonesterified fatty acid (NEFA) concentrations was examined. Angus bulls and steers (10 mo) were allotted to two groups of 12 animals and assigned a treatment order. In a switchback design, animals in order 1 were fed a high grain diet, then fasted, while order 2 animals were fasted, and then fed. Animals were allowed 60 hr to acclimate between treatments. Serum and plasma were obtained at 20 min intervals and 60 min, respectively, for 6 hr after feeding and for the last 6 hr of a 30 hr fast. Serum was assayed for insulin, IGF-I, GH, and cortisol (total and free). Plasma was assayed for PUN and NEFA. Mean insulin (ng/ml) differed between fed (.95 +/- .08) and fasted (.26 +/- .08) animals (P less than 01). Both mean total and free cortisol (ng/ml) were lower in fed (11.48 +/- .99) (1.06 +/- .12) than in fasted (17.10 +/- .93) (1.62 +/- .12) animals, respectively (P less than .01). Animals in order 1 differed in mean IGF-I (ng/ml) between fed (199.0 +/- 8.0) and fasted (116.5 +/- 7.2) treatments (P less than .01). Mean IGF-I for animals in order 2 was 146.7 +/- 7.2 in fed and 213.9 +/- 7.2 in fasted animals (P less than .01). Mean GH did not differ between treatments. Mean PUN and NEFA were higher in fasted than in fed animals (P less than .01). Except for % free cortisol (P less than .05), the hormones did not differ between bulls and steers.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
166.
167.
Despite radically different environmental conditions, terrestrial and martian dunes bear a strong resemblance, indicating that the basic processes of saltation and grainfall (sand avalanching down the dune slipface) operate on both worlds. Here, we show that martian dunes are subject to an additional modification process not found on Earth: springtime sublimation of Mars' CO(2) seasonal polar caps. Numerous dunes in Mars' north polar region have experienced morphological changes within a Mars year, detected in images acquired by the High-Resolution Imaging Science Experiment on the Mars Reconnaissance Orbiter. Dunes show new alcoves, gullies, and dune apron extension. This is followed by remobilization of the fresh deposits by the wind, forming ripples and erasing gullies. The widespread nature of these rapid changes, and the pristine appearance of most dunes in the area, implicates active sand transport in the vast polar erg in Mars' current climate.  相似文献   
168.
ABSTRACT

The aim of this work was to evaluate the effects of isochoric freezing on the quality of tilapia fillet. Isochoric freezing was compared to chilling, super-chilling, and freezing. Isochoric freezing showed muscle color alterations similar to the other preservation methods. All preservation methods resulted in softer fillets, with the isochoric frozen fillet having the most similar texture to that of the fresh sample. Thiobarbituric acid reactive substances (TBARS) for isochoric samples were similar to those of fresh samples. However, there was a 53%, 55%, and 34% increase in TBARS for chilled, super-chilled, and frozen samples, respectively. Total volatile basic nitrogen (TVB-N) content was 1.4 times higher for isochoric samples than for fresh samples. For chilled, super-chilled, and frozen samples, TVB-N content was 3.0, 1.9, and 1.3, respectively, times higher than for fresh samples. Microstructural analysis indicated that isochoric samples showed less cell damage compared to those using other methods. Subfreezing temperatures in conjunction with no ice formation during isochoric freezing contributed to improved quality of tilapia fillet. This study may find application in the commercial preservation of fish to increase shelf life and allow for expanded distribution of raw fish. This study might also be a potential solution to “food desert” areas, where residents have low access to fresh healthy foods.  相似文献   
169.
Summary Cultivar Peking has been extensively used as a source of resistance to Race 3 and Race 5 of soybean cyst nematode, Heterodera glycines I., and Peking genes for resistance are present in a wide range of resistant soybean cultivars. Peking is also used as a host differential in the soybean cyst nematode race classification system. Thirteen Peking lines maintained in the USDA Soybean Germplasm Collection and in several breeding programs were surveyed using RFLP and RAPD markers for genetic characterization. Based on the molecular diversity combined with reaction to soybean cyst nematode, Peking genotypes from a common original source were identified. Peking lines PI 297543 (introduction from Hungary), and PI 438496A, PI 438496B and PI 438496C (introductions from Russia) represented unrelated germplasms. Identified molecular polymorphism can be used to validate the genetic purity of Peking lines used as host differentials for soybean cyst nematode classification system as well as utilization of an individual germplasm line in genetic-breeding programs.  相似文献   
170.
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