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   698篇
  免费   93篇
  国内免费   7篇
林业   83篇
农学   43篇
基础科学   13篇
  20篇
综合类   255篇
农作物   16篇
水产渔业   26篇
畜牧兽医   316篇
园艺   22篇
植物保护   4篇
  2024年   4篇
  2023年   29篇
  2022年   27篇
  2021年   30篇
  2020年   40篇
  2019年   47篇
  2018年   26篇
  2017年   35篇
  2016年   45篇
  2015年   36篇
  2014年   49篇
  2013年   60篇
  2012年   47篇
  2011年   58篇
  2010年   44篇
  2009年   38篇
  2008年   35篇
  2007年   33篇
  2006年   21篇
  2005年   17篇
  2004年   9篇
  2003年   10篇
  2002年   3篇
  2001年   9篇
  2000年   6篇
  1999年   5篇
  1998年   7篇
  1997年   2篇
  1996年   2篇
  1995年   5篇
  1994年   3篇
  1993年   3篇
  1992年   3篇
  1991年   2篇
  1990年   2篇
  1987年   2篇
  1986年   1篇
  1985年   3篇
排序方式: 共有798条查询结果,搜索用时 15 毫秒
721.
Abstract: This paper aims to explain how a number of leading electronics firms from Asian newly industrialised economies of Hong Kong, Singapore, South Korea and Taiwan are articulated into global production networks and become major players in their respective market niches. Developing a triangular theoretical framework, I seek to explain the complex relationships between the dynamic articulation of these leading Asian electronics firms into different global production networks and their simultaneous upgrading from typical followers to market leaders. As a critique of the dominant developmental state discourse, I argue that the interplay between corporate strategies and home base advantages within the context of changing global production networks can offer a better explanation of the differentiated competitive outcomes of these Asian firms. This paper draws upon original data collected through personal interviews with top executives from leading electronics firms in the four Asian newly industrialised economies. I conclude the paper with some implications for theory and policy in relation to corporate development in Asian economies.  相似文献   
722.
为研制风味良好、营养丰富的保健型果肉果冻,以哈密瓜肉和木瓜汁为主要原料,对哈密瓜木瓜新型复合营养果肉果冻的生产配方进行优化,探讨了复合胶的组成与配比,研究哈密瓜果肉、木瓜汁、复合胶、木糖醇、柠檬酸添加量五因素对果冻感官品质的影响。通过单因素试验和正交试验,筛选出以卡拉胶∶魔芋胶∶明胶=2∶1∶1为复合胶,果冻的最佳配方为:哈密瓜果肉添加量8%、木瓜汁添加量10%、复合胶添加量1.0%,木糖醇添加量14%、柠檬酸添加量0.15%,所得到的成品营养丰富,色泽呈均匀橙黄色,酸甜适口,弹性好,平均感官品质评分为94.5分,是一种新型的低糖复合营养果肉果冻,具有较好的市场前景。  相似文献   
723.
简述了人造板设备维修保养的现状和基本内容,并针对我国人造板工业生产设备维修保养存在的问题提出几点建议。  相似文献   
724.
A seasonal migration pattern for silver kob, Argyrosomus inodorus (Griffiths & Heemstra) is elucidated based on tag-recapture data. Spawning adults start migrating southwards against the north-westerly surface currents at the beginning of the austral summer from the northern end of their distributional range to their spawning grounds, Sandwich and Meob Bays, at the southern end of their distributional range. It is suggested that after spawning larvae drift north with the current to the nursery areas, the West coast Recreational area (WCR). When juveniles reach the age of approximately 2 years they will gradually move north towards the adult feeding ground, the Skeleton Coast Park (SCP) waters. At the end of the spawning season when the surf-zone water temperature decreases to about 15 °C adult silver kob complete their spawning cycle by returning to the adult feeding ground, probably moving slightly offshore and with the current.  相似文献   
725.
Abstract –  Underwater cameras were used to observe the breeding behaviour of the endangered eastern freshwater cod, Maccullochella ikei , over 3 years and across three areas in the Mann and Nymboida rivers, Australia. The annual breeding season for M. ikei was short and succinct, lasting only 8–10 weeks. Spawning commenced each year in the lowest altitude area during the first week of spring, and approximately 1 week later in the closest upstream area. Day-length is the primary spawning cue for M. ikei , but increasing water temperature may also be of importance. Nesting sites were located in slow-flowing pools, under cover such as large boulders and bedrock shelves, at depths of 0.9–4.0 m, and with one or two entrances only. The nesting site was vigorously cleaned by the male up to 1 week prior to spawning and was only entered by the female for spawning. Paternal care of eggs and larvae was undertaken for up to 24 days, after which larvae dispersed. Greater protection of breeding M. ikei must be a management priority to ensure long-term conservation of the species.  相似文献   
726.
Glycation, and the resulting buildup of advanced glycation end products (AGEs), is recognized as a key driver of cumulative skin damage and skin aging. Dunaliella salina is a halophile microalga adapted to intense solar radiation through the production of carotenoids. We present a natural supercritical CO2 extract of Dunaliella salina rich in the colorless carotenoids phytoene and phytofluene. The extract exhibited antiglycation and anti-inflammatory activities in ex vivo testing, showing strongly reduced formation of N-ε-carboxy-methyl-lysine with exposure to methylglyoxal, reduced AGE receptor levels, and significantly reduced interleukins 6 and 8. In a placebo-controlled clinical study under intense solar exposure, the extract significantly reduced the skin’s glycation scores and its sensitivity to histamine; key skin aging parameters were also significantly improved vs. placebo, including wrinkle counts and spots. These results demonstrate the value of this Dunaliella salina extract, rich in colorless carotenoids, as an antiglycative, anti-inflammatory, and antiaging active ingredient, including in high-irradiation contexts.  相似文献   
727.
随着乡村振兴战略的提出,乡村旅游迈入高热期,森林旅游作为乡村旅游不可缺少的一部分,也成为相关行业关注的重点.该文运用Citespace软件,以CNKI收录的文献为数据库进行内容分析,梳理我国“森林人家”的研究方向分类、研究历程、研究热点等,总结其现状以及存在的问题,并提出相应的对策与建议.  相似文献   
728.
Objective: To describe the functional outcome of canine and feline survivors of cardiopulmonary arrest (CPA) and the clinical characteristics surrounding their resuscitation. Design: Retrospective study. Setting: Veterinary teaching hospital. Animals: Client‐owned dogs (15) and cats (3) with CPA. Interventions: None. Measurements and main results: Eighteen animals were identified to have survived to discharge following CPA. Cardiopulmonary arrest was associated with anesthesia with or without pre‐existing disease in 10 animals, cardiovascular collapse in 5 animals, and chronic disease with an imposed stress in 3 animals. All CPAs were witnessed in the hospital. The most common initial rhythm at CPA was asystole (72%). Return of spontaneous circulation (ROSC) was achieved in less than 15 minutes from the onset of cardiopulmonary cerebral resuscitation (CPCR) in all animals. No animals had a recurrence of CPA after the initial CPA. Animals were of a wide range of ages (0.5–16 years) and breeds. Two animals were neurologically abnormal at discharge, one of which was normal at 2 months following CPA. Conclusions: A good functional recovery after CPCR was documented in the small number of CPA survivors presented in this study. This may be due to the reversible nature of their inciting cause of CPA, early detections of CPA (‘witnessed’), and/or the animal's underlying normal health status.  相似文献   
729.
Objective To describe the prevalence and risk factors for clinical signs of disease and owner-reported health or welfare issues of aged horses in Queensland, Australia. Methods Owners of horses were contacted via an equestrian organisation in Queensland and asked to complete a questionnaire about their horses aged 15 years and older, to gain information about clinical signs observed in the horse and disease history. Owners were asked to identify health or welfare issues they felt were important in aged horses. Results Owners were able to identify many clinical signs of disease, with 83% of horses having at least one reported clinical sign of disease. Muscle stiffness (33%), lameness (28%), ocular discharge (22%), change in hair coat (22%) and skin problems (21%) were the most commonly reported signs. Increasing age was a risk factor for the presence of clinical signs of disease. Ponies had an increased risk of both laminitis and hirsutism, whereas Thoroughbreds had an increased risk of stereotypies, wounds, weight loss and musculoskeletal signs. Owners reported a known disease or disorder in their horses less frequently than the clinical signs of disease. Owners reported weight loss (28%), arthritis/lameness (24%) and teeth/dental care (18%) as the most important health issues, followed by welfare issues (8%). Conclusion Owners demonstrated concern for the health and welfare of their aged horses, but the lack of appropriate recognition of the significance of clinical signs and limited veterinary care suggest a need for increased client communication and veterinarian–client interaction.  相似文献   
730.
The world-wide financial crisis is the caution that the theory of modernity antinomy tolls for the human beings.As the carrier of social culture,the core value of tea economy,the base and the drive of tea economy,the eventual goal of tea economy and the future of tea economy all lie in the sustainable development of humanities.The core value of tea economy is based on humanities.To get sustainable development of humanities from the perspective of tea economy,great emphasis should be put on developing tea ec...  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