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   365篇
  免费   53篇
  国内免费   17篇
  435篇
  2024年   2篇
  2023年   10篇
  2022年   12篇
  2021年   21篇
  2020年   18篇
  2019年   10篇
  2018年   12篇
  2017年   22篇
  2016年   25篇
  2015年   26篇
  2014年   37篇
  2013年   23篇
  2012年   17篇
  2011年   24篇
  2010年   20篇
  2009年   17篇
  2008年   30篇
  2007年   26篇
  2006年   19篇
  2005年   10篇
  2004年   8篇
  2003年   6篇
  2002年   9篇
  2001年   4篇
  2000年   2篇
  1999年   4篇
  1998年   2篇
  1997年   3篇
  1996年   3篇
  1995年   5篇
  1994年   2篇
  1993年   3篇
  1992年   1篇
  1990年   1篇
  1988年   1篇
排序方式: 共有435条查询结果,搜索用时 0 毫秒
1.
M. H. Losvik 《Plant Ecology》1988,78(3):157-187
Well-drained mown hay meadows in Hordaland, western Norway, were investigated. The hay meadows are either managed in a traditional or in a semi-traditional way. Traditional management in the area involves little or no use of manure or fertilizer, mowing once or twice a year with a first cut later than June 23, clearing in spring and intensive grazing for short periods in spring and autumn. Semi-traditional management involves use of small to medium quantities of commercial fertilizer, often in addition to manure. Grazing may be irregular, light or lacking.Eight units of hay meadow vegetation are described, all assigned to the class Molinio-Arrhenatheretea, order Arrhenatheretalia; four units to the Atlantic alliance Cardaminion pratensis, association Cardamino pratensis-Conopodietum majoris (with three subassociations); one unit to the alliance Arrhenatherion elatioris, three units are provisionally grouped as Galium uliginosum-Knautia arvensis meadows.Continuous management of these meadows has resulted in characteristic species compositions, which vary along a west-east climatic gradient, and are related to the amount of commercial fertilizer used and the natural mineral-content of the soil.These hay meadows seem to be best maintained by continuing the traditional management regime. Grazing in spring and in autumn reduces fast growing dominants and creates openings for new seedlings of annuals and biennials. A late first cut allows for ripening of the seeds and creates openings for light for the species of the lower field layer. A list of species characteristic of traditionally managed permanent hay meadows is presented, and possible effects of present changes in management on the species composition of the meadows are discussed.The amount of organic matter in the topsoil is small in most stands. The pH values are between 4.0 and 5.6. The highest values were recorded in soil where little or no commercial fertilizer is used, and where the subsoil is naturally rich in minerals. A tendency to Mg impoverishment in the best fertilized stands is demonstrated. Species-rich stands on Ca-rich soils are poor in P.The expected changes in vegetation, future use, and conservation of permanent hay meadows in Hordaland are discussed.  相似文献   
2.
传统大豆发酵食品在心脑血管疾病防治上的研究现状   总被引:1,自引:0,他引:1  
人类生活水平的提高以及生活压力的增加,使心脑血管疾病的发生频率显著增加,并日趋成为威胁人类健康的重要原因。传统大豆发酵食品中的各种生理活性物质通过降血压和调节体内脂质、糖类代谢等多种作用来有效地防治心脑血管疾病;与传统药物相比,有效果显著与无毒副作用等优点,因此传统大豆发酵食品有广阔的发展应用前景。  相似文献   
3.
血脂异常及动脉粥样硬化中医研究进展   总被引:1,自引:0,他引:1  
“血脂异常”及“动脉粥样硬化”是现代医学病名,古代医书中虽无此病名记载,但却不乏与之相关的论述.现代中医根据其临床表现将其归属于“眩晕”、“胸痹”、“中风”、“痰浊”、“血瘀”、“脉痹”、“血痹”、“脱疽”等病症范畴.现代中医学者对血脂异常、动脉粥样硬化的中医病名认识、病因病机探讨及二者之间的联系进行了大量的理论和实验研究,对血脂异常和动脉粥样硬化有了新的认识.动脉粥样硬化是引起心脑血管疾病的首要原因,也是其发病的病理基础,而血脂异常又是动脉粥样硬化发病的主要因素之一.故对血脂异常和动脉粥样硬化发病机制及防治策略的研究,不仅是西医研究的热点,同时也是中医中药研究重点,值得我们一生探索.  相似文献   
4.
1993年生效的《生物多样性公约》(CBD,the Convention on Biological Diversity)将获取与惠益分享(ABS,access and benefit sharing)作为其三大目标之一。2010年在CBD缔约方大会第10次会议(COP-10)上达成了《生物多样性公约关于遗传资源获取与公平和公正地分享其利用所产生惠益的名古屋议定书》(简称"《名古屋议定书》"),标志着获取与惠益分享议题取得了实质性进展。随后又组织召开了3次政府间委员会会议,《名古屋议定书》于2014年10月在韩国平昌召开COP-12期间生效,并在2014年10月13-17日召开了《名古屋议定书》缔约方大会第1次会议(COP/MOP-1)。本文系统总结和梳理了获取与惠益分享议题产生背景、关键议题争论的焦点、谈判历程和发展动态,深入分析了欧盟、非洲集团、瑞士等主要国家集团和非政府组织(NGOs)、工商界等非国家行为体(NSAs)在获取与惠益分享国际谈判中的立场、策略和作用,讨论了《名古屋议定书》对发展中国家和发达国家的利益体现、影响以及中国面临的挑战。  相似文献   
5.
摘要 目的:观察中医正骨手法在桡骨远端伸直型骨折中的临床应用价值,并分析疗效的影响因素。方法:选择四川省骨科医院2020年1月~2022年1月期间收治的桡骨远端伸直型骨折患者152例,按照治疗方式的不同将患者分为对照组(给予石膏固定)和研究组(应用中医正骨手法治疗),例数分别为77例和75例。对比两组优良率、临床指标、腕关节活动度和X线相关影像学指标。同时采用多因素Logistic回归分析影响研究组腕关节功能疗效的相关因素。结果:治疗后,研究组的优良率明显高于对照组(P<0.05)。研究组手背消肿时间、疼痛缓解时间、骨折愈合时间均短于对照组(P<0.05)。两组治疗后12周掌屈、背伸、桡偏、尺偏、旋前、旋后活动度均扩大,且研究组均大于对照组(P<0.05)。两组治疗后12周掌倾角、尺偏角、桡骨高度均增加,且研究组均大于对照组(P<0.05)。单因素分析显示,研究组腕关节功能优良率与年龄、性别、骨质疏松、功能锻炼、掌倾角、尺偏角、桡骨高度、骨折端稳定性、受伤能量、利手情况有关(P<0.05),而与体质量指数、就诊时间、基础疾病、骨折类型、固定时间无关(P>0.05)。多因素Logistic回归分析显示:性别为女、骨质疏松、无功能锻炼、掌倾角偏小、桡骨高度偏短、骨折端不稳定、受伤能量为高能量、利手是影响腕关节功能优良率的危险因素(P<0.05)。结论:中医正骨手法可有效改善桡骨远端伸直型骨折患者腕关节功能,减少骨折愈合及疼痛缓解时间。此外,患者腕关节功能的优良率还受到性别、骨质疏松、功能锻炼、掌倾角、桡骨高度、骨折端稳定性、受伤能量、利手情况的影响,值得引起临床重视。  相似文献   
6.
本文阐述了中药防治病毒病的历史及其应用概况,中药联合微生态制剂防治呼吸、消化系统病毒病的理论依据、临床应用和发展前景。  相似文献   
7.
Propolis is widely used as traditional medicine since ancient times. It was necessary to conduct the pre-clinical study because of its relevant curative properties. This study aimed to investigate in-vitro antioxidant, standardize quality parameters, study acute toxicity, and determine in-vivo anti-inflammatory. Three spectrophotometric methods were used to determine antioxidant activity. The standardization includes physical, chemical, and microbiological evaluation. Furthermore, an acute toxicity test was conducted using 20 female Sprague Dawley (SD) strain rats divided into 4 groups with different dose of propolis. The in vivo anti-inflammatory test was carried out using the carrageenan induction method on rats' soles. A total of 36 female SD rats were classified into 6 groups as follows, Group normal, negative control, diclofenac sodium, and three propolis groups (72; 144; and 288 mg/kg BW). The results demonstrated the IC50 values of the DPPH and ABTS scavenging activity 9.694 ppm and 2.213 ppm, respectively. The FRAP reducing power was 189.05 mg AaE/g. The physical appearance of propolis capsule was vegicaps as white – white, size 0, with light brown granule. Moreover, the content weight was 418.88 mg with a disintegration time of 7 min 53 s, while the water, flavonoid, and polyphenol contents were 9.07%, 1.59%, and 98.0821 mg GAE/g respectively. The content of heavy metal and microbial contamination were not detected. The acute toxicity results showed LD50 ≥ 5 g/kg BW, no toxicity symptoms, and no abnormalities in all rats. The anti-inflammatory inhibition percentage for groups III, IV, V, and VI was 11.86%, 6.53%, 7.81%, and 6.63% respectively, while the anti-inflammatory drugs effectiveness percentage compared to positive controls were 55.00%, 65.83%, and 55.83% respectively. Based on these results, it can be concluded that propolis capsules fulfilled the standardization requirements, and it is likely to be non-toxic, and effective as antioxidant and anti-inflammatory.  相似文献   
8.
2008及2009年两次考察收集了云南省贡山独龙族怒族自治县独龙江乡,6个独龙族村寨的农业生物资源及其传统知识。考察发现独龙族栽种、管理和利用了包括30.4%的粮食、49.7%的蔬菜和17.7%的果树等丰富的农业生物种质资源,共收集到181份种质;独龙族积累了大量的利用农业生物资源的传统知识,如董棕(Caryota urans L.)粉、漆油鸡、漆油酥油茶和木瓜(Fructus chaenomelis speciosae)豆腐等传统食物加工与烹调方法的传统知识。  相似文献   
9.
肠道菌群是人体内环境的重要组成部分,可影响机体的代谢、免疫和炎症反应,与原发性高血压的发生发展密切相关,已成为防治高血压的研究热点。中药在临床用于原发性高血压的治疗且疗效显著。研究表明中药可被肠道菌群分解代谢为易于吸收的活性物质,而这些活性物质又可通过调节肠道菌群结构及其代谢产物防治高血压。本文以肠道菌群作为切入点,通过分析肠道菌群与原发性高血压发生发展的关系和中药在调节原发性高血压肠道菌群方面的研究,总结中药通过调节肠道菌群防治原发性高血压的作用和机制,以期为中药防治高血压及药物研发提供新的研究思路。  相似文献   
10.
Wood-pastures are fragile ecosystems because they were formed by, and depend on specific, low-intensity multifunctional management. Although their ecological and cultural significance is high, wood-pastures are rapidly deteriorating all over Europe, mainly due to changing land use. We still lack a basic understanding of the ecological value of wood-pastures, and in which features they differ from other landscape elements. In this paper we investigated the ecological value of wood-pastures for passerine birds by (i) comparing bird assemblages of wood-pastures with those of closed forests and open pastures and (ii) exploring the relationships between variables describing wood-pastures and species traits of the bird assemblages. Our study region (Southern Transylvania, Romania) provides a unique opportunity to understand the importance of a traditional cultural and ecological environment for many different organisms. Wood-pastures had a higher overall number of bird species, and a higher spatial turnover in bird community composition than closed forests and open pastures. We found significant associations between bird species traits and habitat structural elements in wood-pastures such as large trees, oak- and pear trees and shrubs. Our findings suggest that traditional wood-pastures in Southern Transylvania have distinct and rich passerine bird communities. This richness is inextricably linked to the multifunctional, low-intensity land use traditionally applied in the wood-pastures that promotes high niche diversity. For effective conservation of the biodiversity of wood-pastures, a detailed understanding is needed of how different management regimes may influence the key structural elements of wood-pastures relevant for biodiversity and these should be protected.  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