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   164篇
  免费   1篇
林业   7篇
农学   2篇
  20篇
综合类   7篇
农作物   8篇
水产渔业   14篇
畜牧兽医   88篇
园艺   8篇
植物保护   11篇
  2022年   4篇
  2021年   1篇
  2019年   4篇
  2018年   3篇
  2017年   4篇
  2016年   3篇
  2015年   1篇
  2014年   2篇
  2013年   13篇
  2012年   4篇
  2011年   6篇
  2010年   7篇
  2009年   4篇
  2008年   3篇
  2007年   11篇
  2006年   15篇
  2005年   10篇
  2004年   6篇
  2003年   8篇
  2002年   5篇
  2001年   11篇
  2000年   11篇
  1999年   8篇
  1998年   2篇
  1997年   2篇
  1996年   1篇
  1994年   2篇
  1991年   1篇
  1989年   1篇
  1982年   1篇
  1980年   1篇
  1979年   2篇
  1975年   3篇
  1974年   1篇
  1973年   1篇
  1971年   1篇
  1970年   1篇
  1969年   1篇
排序方式: 共有165条查询结果,搜索用时 171 毫秒
101.
Aurapten (7-geranyloxycoumarin) has been reported to be an effective inhibitor of chemical carcinogenesis in some rodent models. In the present study, a method for preparing an aurapten-enriched agricultural product has been established. Out of 17 Rutaceae varieties, the aurapten content in hassaku (Citrus hassaku Hort ex Y. Tanaka) fruit peel was marked, as well as that in natsumikan (C. natsudaidai) and grapefruit (C. paradisi). The aurapten content in hassaku peel was most abundant in April. Hassaku fruit peel oil, which was dissolved by heating precipitates including aurapten which had formed after freezing the peel oil at -20 degrees C, was used. After adsorbing aurapten from peel oil onto synthetic adsorbent SP70, the adsorbent was washed with 40% (v/v) ethanol in water to remove essential oils and pigments remaining on the adsorbent. Aurapten was then eluted with 80% (v/v) ethanol. In a laboratory-scale test, the recovery rates of aurapten and total carotenoids from the eluates were 74.3 and 4.6%, respectively. In a pilot-scale test, the recovery rate of aurapten in the aurapten-enriched preparation from dissolved hassaku oil was 91.0%, and its concentration was 64.1% (w/w). When stored for 180 days under sunlight, aurapten in powder form remained at 88.0-89.0% of the initial level, but only 31.3-43.8% in ethanol. The stability of aurapten in the aurapten-enriched preparation was higher than that of purified aurapten. These results suggest that aurapten is readily recovered from hassaku peel oil using SP70, and thus may be used as a food additive.  相似文献   
102.
Balloon dilation was performed on a dog with tetralogy of Fallot. Immediately following balloon dilation, the peak systolic pressure gradient across the pulmonic valve declined from 97 to 63 mmHg. Doppler echocardiography following balloon dilation revealed increased pulmonary blood flow. Clinical symptoms obviously improved and the dog's improved condition was maintained for 4 months. There were no serious complications in performing the procedure. It was concluded that balloon dilation was a safe and effective treatment for a dog case with tetralogy of Fallot. Long-term follow-up studies will be required to identify the exact indications of balloon dilation for tetralogy of Fallot.  相似文献   
103.
The insecticidal activities of imidacloprid derivatives with a wide range of substituents at the 5-position on the pyridine ring against American cockroaches, Periplaneta americana (L.), were measured by injection with and without synergists propyl 2-propynyl phenylphosphonate and piperonyl butoxide. The log(1/MLD) value (MLD = minimal lethal dose in mol) without synergists was 7.96 for the methyl derivative, and the values were lower for other derivatives. Synergists enhanced the potencies of all the compounds tested. Considering these compounds and those with other substituents at this position, the region for maximum activity was predicted to be in the conjunction of the pyridyl 6-chlorine atom with a lipophilic small group in the 5-position.  相似文献   
104.
An 8-month-old entire Miniature Dachshund, weighing 4.2 kg, was presented for examination following delvelopment of a cough. Ventricular septal defect had been diagnosed tentatively in its infancy on the basis of a cardiac murmur detected by auscultation and echocardiography. Echocardiography using a B mode right parasternal long-axis view showed a defect at the atrioventricular junction and a thickened cusp of the aortic valve prolapsing into the defect. Colour-flow Doppler showed shunt blood flow across the defect at the level of the atrioventricular junction, from left to right. The sinus of Valsalva was dilated, with turbulent blood flow. Aortic regurgitation was also observed. Cardiac catheterisation studies confirmed the diagnosis of a supracristal ventricular septal defect with aortic regurgitation. Despite medication with digoxin, enalapril and aminophylin, started from the first admission, left ventricular internal dimensions gradually increased, and fractional shortening of the left ventricle gradually decreased. Surgery, with the aid of extracorporeal circulation, to close the ventricular septal defect, was performed 1 year after the initial examination. The aortic valve was left untreated. Postoperatively, the systolic murmur disappeared. Shunt flow from the left to the right ventricle was no longer observed on echocardiography, however there was still a small amount of aortic regurgitation during diastole visualised with colour-flow Doppler echocardiography. The prolapse of the cusp of the aortic valve on B-mode echocardiography was no longer observed and thickening of the cusp had not progressed. Left ventricular function measurement using M mode echocardiography showed a reduced left ventricular volume overload with reduced left ventricular internal dimensions and increased fractional shortening. The cough was relieved and no follow-up medication was scheduled. Early surgical closure of the ventricular septal defect improved the patient's condition and controlled prolapse and thickening of the aortic valve.  相似文献   
105.
Primary chondrosarcoma was found in the quadrate lobe of the liver of a 6-year-old, intact, male Golden Retriever. At 6 months after partial hepatectomy, recurrence in the liver occurred. The dog died of its systemic metastases 10 months thereafter. Histologically, the hepatic mass revealed neoplastic chondrocytes with abundant chondroid matrix, and there were few myxoid areas where the cellularity and pleomorphism of the neoplastic cells were more prominent. The neoplastic cells were positive for periodic acid-Schiff and were immunohistochemically positive for vimentin and S-100 protein; the matrix was deeply stained for alcian blue and was metachromatic for toluidine blue stain. This tumor might be derived from pluripotent mesenchymal cells in the connective tissue of the liver. To the best of our knowledge, in all mammalians, including humans, this is the first report of extraskeletal chondrosarcoma primarily arising in the liver.  相似文献   
106.
alpha-klotho was identified as a gene associated with premature aging-like phenotypes characterized by short lifespan. In mice, we found the molecular association of alpha-Klotho (alpha-Kl) and Na+,K+-adenosine triphosphatase (Na+,K+-ATPase) and provide evidence for an increase of abundance of Na+,K+-ATPase at the plasma membrane. Low concentrations of extracellular free calcium ([Ca2+]e) rapidly induce regulated parathyroid hormone (PTH) secretion in an alpha-Kl- and Na+,K+-ATPase-dependent manner. The increased Na+ gradient created by Na+,K+-ATPase activity might drive the transepithelial transport of Ca2+ in cooperation with ion channels and transporters in the choroid plexus and the kidney. Our findings reveal fundamental roles of alpha-Kl in the regulation of calcium metabolism.  相似文献   
107.
108.
Oxidation of low-density lipoprotein (LDL) has been implicated in atherogenesis. Antioxidants that prevent LDL from oxidizing may reduce atherosclerosis. This study investigated LDL antioxidant activity in edible plant products for development of dietary supplementation to prevent atherosclerosis. Fifty-two kinds of edible plants were extracted using 70% aqueous ethanol solution, and the antioxidant activity of the extracts, which inhibit human LDL oxidation induced by copper ion, was determined on the basis of the oxidation lag time and represented as epigallocatechin 3-gallate equivalent. 1,1-Diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity and total phenolic content were also measured for comparisons with antioxidant activity in LDL. Plant products showing the greatest activity in LDL oxidation assay were akamegashiwa (Mallotus japonicus) leaf, Japanese privet (Ligustrum japonicum) leaf, green tea [Camellia sinensis (L.) O. Kuntze], and astringent persimmon (Diospyros kaki). The present study revealed high levels of LDL antioxidant activity in plant products for which such activity levels are underestimated in the DPPH radical scavenging assay and Folin-Ciocalteu assay.  相似文献   
109.
Continuous body weight dynamics in supplementally fed free-ranging sika deer (Cervus nippon) during the three consecutive overwinters (from January to April), 1992–1994 were surveyed. Almost all individuals lost weight continuously throughout each winter (adult deer 5–13%; young deer 3–19%) and several deer lost weight even in April. Weight gain after loss began in the mid-April when ambient temperature increased and when plant growth began. Weight dynamics varied according to sex, age and reproductive status. Adult deer showed significant large weight loss than the young. Young deer lost weight (calves 18±11 g/day, yearling and two-year-olds 27±29 g/day) more slowly than the adults (65±23 g/day). Following this study of over-winter body weight dynamics, it seems that early springs are the most critical periods for the survival of free-ranging sika deer because of their poor nutritional condition. A portion of this report was presented at the 106th Annual Meeting of the Japanese Forestry Society (1994).  相似文献   
110.
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