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   104篇
  免费   6篇
林业   3篇
农学   1篇
  6篇
综合类   48篇
畜牧兽医   50篇
园艺   1篇
植物保护   1篇
  2020年   2篇
  2019年   1篇
  2018年   1篇
  2017年   2篇
  2016年   3篇
  2013年   3篇
  2012年   1篇
  2011年   3篇
  2010年   1篇
  2009年   3篇
  2008年   3篇
  2007年   4篇
  2006年   3篇
  2005年   7篇
  2004年   3篇
  2003年   1篇
  2002年   4篇
  2000年   3篇
  1999年   2篇
  1998年   2篇
  1997年   1篇
  1996年   5篇
  1995年   1篇
  1993年   6篇
  1992年   4篇
  1991年   3篇
  1989年   3篇
  1985年   1篇
  1984年   1篇
  1983年   5篇
  1982年   1篇
  1980年   1篇
  1978年   1篇
  1976年   1篇
  1975年   1篇
  1974年   2篇
  1972年   2篇
  1971年   2篇
  1970年   2篇
  1969年   2篇
  1968年   3篇
  1967年   1篇
  1956年   1篇
  1954年   1篇
  1948年   1篇
  1947年   1篇
  1945年   1篇
  1937年   1篇
  1931年   1篇
  1928年   1篇
排序方式: 共有110条查询结果,搜索用时 296 毫秒
1.
SUMMARY Twenty-five Thoroughbred (TB) and 25 Standardbred (SB) stables were visited to determine their feeding practices. The ingredients of the main feed of the day for a mature gelding of average size in full training were weighed at each stable. Nutrient content of diets was calculated using published data for the individual ingredients. Results are expressed as mean±sd. The estimated body weight of TB horses was 493±34 kg and 437±32 kg for SB horses. There was considerable variation in diet composition and nutrient intake between stables. The TB trainers fed 11.0±2.4 kg and SB trainers 11.8±2.5 kg per day. The concentrate component of the diet weighed 7.8±1.6 and 7.7±2.3 kg for TB and SB stables, respectively, and the roughage component for TB horses 3.3±1.4 and SB horses 4.1±1.4 kg per day. The digestible energy intake of horses at TB stables was 129±29 MJ per day and at SB stables 132±31 MJ per day. Crude protein intake of TB horses was 1452±363 g and SB horses 1442±338 g per day. There were differences in some feeding practices at TB and SB stables. Standardbred trainers fed more roughage than TB trainers. Standardbred trainers fed chaffed lucerne (alfalfa) and cereal hays as the major roughage, whereas TB trainers fed more hay. The major hay type fed by TB trainers was lucerne, whereas many SB trainers preferred clover hay. Both trainers fed oats as the major grain, but TB trainers fed slightly more maize (corn) than SB trainers. The SB trainers fed barley as part of the concentrate component of the diet, whereas TB trainers usually fed boiled barley and linseed oil in winter only. Although many trainers used vitamin and mineral supplements, this appeared unnecessary in many Instances, especially with respect to Iron. Calcium and NaCI supplementation was necessary for some diets. We concluded that while there was a wide range in feed intake and diet composition for both TB and SB horses, average nutrient intakes were similar to National Research Council (1989) recommendations for horses performing intense work.  相似文献   
2.
3.
An array of alternating anion and cation exchange membranes can be used to generate electric power from the free energy of mixing of river and sea waters. A simple mathematical model, which predicts experimental results well, is useful in exploring conditions for optimization of the process. Major, but not impossible, improvements in technology would be required to bring the cost of power from the dialytic battery into line with foreseeable energy prices.  相似文献   
4.
5.
6.
7.
The tumor promoters 12-O-tetradecanoyl-phorbol-13-acetate and teleocidin markedly enhanced the transformation of C3H 10T1/2 mouse fibroblasts when these cells were transfected with the cloned human bladder cancer c-rasH oncogene. Transfection studies with the drug resistance marker gpt and time course studies indicate that this enhancement is not simply an effect on the process of DNA transfection. These findings, together with parallel studies with NIH 3T3 fibroblasts, also indicate that the competence of animal cells for DNA transfection is a function of the recipient cell line, the transfected marker, and the growth conditions. Our findings suggest that during multistage carcinogenesis tumor promoters may complement the function of activated cellular oncogenes.  相似文献   
8.
Cost-effective priorities for cancer prevention   总被引:1,自引:0,他引:1  
Faced with limited resources, the United States must set priorities for research to identify preventable causes of cancer. A quantitative approach to priority setting, based on principles of decision analysis and cost-effectiveness analysis, can offer guidance in this process. An illustrative application of such a model suggests that the National Institutes of Health-supported clinical trial of dietary beta-carotene offers a greater expected reduction in cancer mortality per research dollar than carcinogen bioassays of high-volume industrial chemicals such as p-dichlorobenzene. National research priorities should reflect the relative cost-effectiveness of such investments.  相似文献   
9.
10.
一.緒言現行的役馬飼養標準,為數甚多。由於工作的計算困難,大都祇對於某種農業情况,加以大約的估計,因此用量的大小極不一致,而又無適當可行的辦法加以比較,以便抉擇。此中情況,林敦氏(1950)有言,"最好的方法是按照下述的辦法來飼養,如感覺馬的體情退化則增加飼量,如馬有長肥的傾向則減少之"。同樣波波夫亦謂,"必須不斷地注意馬的體况,並根據觀察結果,經常調整馬的日糧"(1954)。似此,則役馬的飼養仍處於一種技術修養的狀態,談不到定額矣。本文的目的在提出一衡量工作的尺度,根據此尺度,測驗各家的標準,並從而求出一比較合理的標準,此標準不但要按照飼養乳牛的辦法,計役授糧,而且要應用簡便,易於實行。此外,不同輕重及種類的工作,經測定各種的常數以後,亦可以納入本方法之中,俟一一論及之。  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