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   316篇
  免费   8篇
林业   20篇
农学   13篇
基础科学   1篇
  37篇
综合类   6篇
农作物   13篇
水产渔业   85篇
畜牧兽医   121篇
园艺   13篇
植物保护   15篇
  2023年   5篇
  2022年   5篇
  2021年   14篇
  2020年   5篇
  2019年   7篇
  2018年   7篇
  2017年   10篇
  2016年   8篇
  2015年   11篇
  2014年   21篇
  2013年   18篇
  2012年   16篇
  2011年   29篇
  2010年   9篇
  2009年   15篇
  2008年   18篇
  2007年   24篇
  2006年   21篇
  2005年   16篇
  2004年   16篇
  2003年   11篇
  2002年   11篇
  2001年   12篇
  2000年   3篇
  1998年   1篇
  1997年   2篇
  1993年   3篇
  1991年   2篇
  1989年   1篇
  1987年   2篇
  1979年   1篇
排序方式: 共有324条查询结果,搜索用时 265 毫秒
311.
OBJECTIVE: To evaluate the safety of reduced-dosage ketoprofen (RDKET) for long-term oral administration in healthy dogs. ANIMALS: 14 healthy Beagles. PROCEDURES: Racemic ketoprofen (0.25 mg/kg, PO) and gelatin capsules, as a drug-free placebo, were each administered to 7 dogs for 30 days. Dogs were periodically monitored via physical examination, blood analyses, endoscopic examinations, fecal occult blood tests (tetramethylbenzidine and guaiac methods), renal function tests (effective renal plasma flow and glomerular filtration rate), urinalyses, urinary enzyme indices (N-acetyl-beta-D-glucosaminidase and gamma-glutamyl-transferase), and hemostatic function tests (buccal mucosa bleeding time, cuticle bleeding time, prothrombin time, activated partial thromboplastin time, and fibrinogen concentration). RESULTS: Pyloric antrum lesion grade was significantly higher in the RDKET group on day 28, compared with the pretreatment and control group grades. Fecal occult blood grade measured by use of the tetramethylbenzidine method was significantly higher in the RDKET group on day 30, compared with the pretreatment grade. No other significant differences were detected between treatment groups. CONCLUSIONS AND CLINICAL RELEVANCE: RDKET induced mild to moderate gastric mucosal injuries especially in the pyloric antrum in healthy Beagles, whereas no adverse effects were observed in renal function or hemostasis. Fecal occult blood tests may be useful as screening tests for adverse gastrointestinal effects induced by RDKET in dogs.  相似文献   
312.
313.
Vientiane, Lao PDR, has been subject to extensive and ongoing urbanization plans, including development of natural marshes and residentialization of paddy fields into suburban areas, despite natural marshes playing a vital role in treating wastewater from urban areas. Therefore, it is important to understand the current situation regarding the nutrient balance in these natural wastewater treatment systems to predict future conditions and design appropriate measures against water quality deterioration. However, limited data are available in Vientiane on the hydrological characteristics of water and nutrient runoff that flow into marshes through drainage canals. In this study, we conducted a periodic survey of drainage canals and Mak Hiao River in the wastewater catchment system surrounding Vientiane during the rainy and dry seasons. We monitored the discharge of surface water at 21 observation sites and analyzed water quality of nitrogen, phosphorus, and total organic carbon. These observations revealed that the concentrations of dissolved nitrogen and phosphorus were significantly higher at sites in urban areas, followed by sites in the main river basin and those in agricultural areas. Dissolved nitrogen and phosphorus concentrations varied with runoff discharge, especially in urban and river basin sites, with lower concentrations in the rainy season and higher concentrations in the dry season. On the other hand, we found no significant differences between the rainy and dry seasons in nutrient concentrations in the agricultural basin. Finally, we proposed measures to counteract the deterioration of water quality during dry seasons and simulated the impact of these measures.  相似文献   
314.
315.
1. The skulls and postcranial skeletons of the red jungle fowl (Gallus gallus) were compared osteometrically between the populations from North and South Vietnam, North and Central Laos and Southeast Bangladesh. The populations include the three subspecies of G. g. spadiceus, G. g. gallus and G. g. murghi and were sampled to reveal the geographical morphological variations among populations in G. gallus.

2. The morphometric characteristics of subspecies murghi could be clearly distinguished from those of the other subspecies using a canonical discriminant analysis. However, the size and shape of the skull of the gallus population from South Vietnam were not statistically different from that of the subspecies spadiceus from North Laos. The canonical discriminant scores also clearly indicated that there were morphological similarities in the skulls of the populations from North Laos and South Vietnam.

3. From the results, therefore, it is concluded that red jungle fowls do not exhibit high levels of osteometric variation between geographical localities at least within the Indochinese Peninsula.

4. This contrasts with previous studies which have described these subspecies as having various external morphological differences and have argued that zoogeographical barriers exist between the north and south areas of the Indochinese Peninsula.  相似文献   

316.
317.
The objective of this study is to clarify the relationships between tree sizes and the anatomical, chemical, and physical characteristics of reaction wood. Naturally inclined stems or branches in 23 Japanese angiosperms, including 3 tree sizes at adult trees, 7 arbor, 7 subarbor, and 9 shrub species, were used. The presence of a gelatinous (G-) layer, basic density, vessel frequency, and lignin content were examined on the upper and lower sides of each sample. Almost all the species showed a decrease in vessel frequency and lignin content on the upper side, which are typical characteristics of reaction wood in angiosperms. A G-layer was formed in four arbor, one subarbor, and two shrub species. The ratio of the upper and lower sides in vessel frequency and lignin content gradually decreased with an increase in tree size. Based on the results of the principal component and cluster analyses, shrub species were classified into the different groups: from arbor and subarbor groups. These results indicate that the magnitude of alteration in the characteristics due to reaction wood formation of arbor and subarbor might differ from that of shrub, although the characteristics changed by reaction wood formation might be the same in the three tree sizes at adult trees.  相似文献   
318.
本研究以日本京都大学农学部生殖质研究所人工合成小麦品系和普通小麦品种“中国春”为材料,种子根为外植体诱导出愈伤组织和不定根,对其染色体数目的变异进行了分析比较。结果表明,品系间愈伤组织细胞的染色体变异有很大差别,品系89W36的变异幅度较大2n=7~58,品种“中国春”(88W70)的染色体变异较小2n=15~43。 小麦染色体组基数 X=7的整倍体 14、21、28、35、42的变异频率都大于相近数目的非整倍体。小麦正常染色体数42的频率比其他数目的变异高。不定根染色体的变异与愈伤组织相比相对稳定,最大变异范围是2n=25-45,染色体数的变异主要集中在39~44,各品系正常染色体数42的细胞频率都在68%以上。  相似文献   
319.
Various physiological functions of dietary glucosylceramides (GlcCer) have been reported, such as preventing colon cancer and improving skin barrier function. One potential GlcCer source used as a foodstuff is sea cucumber. In this study, our objective was to determine the effect of dietary GlcCer prepared from sea cucumber on plasma and liver lipids in cholesterol-fed mice. ICR mice were fed four different diets (control diet, sea cucumber GlcCer supplemented diet, high cholesterol supplemented diet, and high cholesterol + sea cucumber GlcCer supplemented diet). Dietary GlcCer decreased total cholesterol significantly in ICR mice. The mRNA expression of LDL receptor was increased significantly, while the expression of the gene CYP7A1, which is involved in bile acid formation, was decreased significantly compared with the control (diet without cholesterol). These results suggest that the expression of the cholesterol homeostasis gene in liver is modulated due to the cholesterol lowering effect of dietary GlcCer.  相似文献   
320.
Protamine is a basic protein whose sulfate is used in medical applications as a carrier for injectable insulin and as a heparin antagonist, while its hydrochloride is used as an antibacterial ingredient for some food products. We previously showed that protamine hydrochloride derived from chum salmon milt inhibited pancreatic lipase and reduced plasma triacylglycerol levels in an oral fat tolerance test in humans. The present study evaluated the effect of chum protamine hydrochloride on lipid metabolism in rats. The single oral administration of protamine hydrochloride (500 mg/kg) reduced plasma triacylglycerol levels in a corn oil tolerance test, and repeated oral administration at a dose of 0, 150, 500, or 1,500 mg/kg with a high fat diet for 7 weeks significantly reduced body weight gain, liver weight, and epididymal adipose tissue, whereas total calorie intakes were not significantly different. These findings could be caused by the suppression of lipid digestibility leading to a significant increase in fecal lipid excretion due to the fact that protamine hydrochloride could bind with bile acids to make a complex that is difficult to digest. Protamine hydrochloride, with a considerable history as food, can be considered to be promising as an anti-obesity functional food material.  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