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   476篇
  免费   12篇
  国内免费   9篇
林业   83篇
农学   16篇
基础科学   19篇
  40篇
综合类   159篇
农作物   28篇
水产渔业   60篇
畜牧兽医   67篇
园艺   13篇
植物保护   12篇
  2024年   2篇
  2023年   3篇
  2022年   17篇
  2021年   16篇
  2020年   11篇
  2019年   15篇
  2018年   11篇
  2017年   6篇
  2016年   12篇
  2015年   23篇
  2014年   26篇
  2013年   26篇
  2012年   22篇
  2011年   18篇
  2010年   30篇
  2009年   35篇
  2008年   31篇
  2007年   49篇
  2006年   27篇
  2005年   23篇
  2004年   19篇
  2003年   8篇
  2002年   10篇
  2001年   8篇
  2000年   4篇
  1999年   10篇
  1998年   3篇
  1997年   5篇
  1996年   5篇
  1995年   8篇
  1994年   1篇
  1993年   2篇
  1992年   4篇
  1991年   3篇
  1990年   1篇
  1989年   1篇
  1988年   1篇
  1985年   1篇
排序方式: 共有497条查询结果,搜索用时 15 毫秒
41.
日本林业防灾减灾政策支持体系及借鉴   总被引:1,自引:0,他引:1  
我国是一个林业灾害多发、频发的国家, 森林火灾、有害植物入侵、病虫鼠害、雨雪冰冻、洪水、滑坡、泥石流等各种灾害时有发生, 给森林资源和林业产业造成巨大威胁。日本灾害预防和救治管理体系完善, 经验值得借鉴。文中概述了日本防灾管理的法律体系和预算体系, 重点阐述了日本林业防灾预算体系、重大灾害防治制度和重大灾害追加预算制度, 针对我国林业防灾体系建设提出应完善法律体系和政策支持体系、建立林业灾害管理等级制度等建议。  相似文献   
42.
On the basis of 268 direct sika deer observations and 212 ratio locations of three individuals, the influence of snow on deer distribution was studied. During the period of snow absence or its shallow cover, the deer did not show any preferences towards slope aspect. However, when the snow coverage became deeper, the deer used westerly exposures (having shallower snow cover) more intensively. Later on, when the snow started to melt on the easterly slope aspects deer mostly used those exposures due to relatively abundant food resources.  相似文献   
43.
Supply of clear, unstained logs from an export country is important economically as well as in reducing the biosecurity risk to an importing country such as Japan. Although conditions found within the holds of ships containing logs are thought to be ideal for rapid colonization of sapstain fungi, no research has been conducted. Research-focussed log export trials were designed to determine the extent of sapstain colonisation at specific points in the processing of logs from harvesting to arrival at the export destination. Two trials were established, in the austral summer and winter, in which mature Pinus radiata logs were harvested in New Zealand and shipped to export ports in Japan. Data loggers placed above and below deck of the ships recorded microclimatic conditions. Nine species of sapstain fungi were isolated from logs during the summer trial; the most common species isolated were Ophiostoma floccosum, Ophiostoma querci, and Ophiostoma setosum. In contrast, ten sapstain species were detected during the winter trial, with Sphaeropsis sapinea, O. querci, O. floccosum, and O. setosum most commonly isolated. This research was the first successful attempt at measuring visual sapstain development and isolating sapstain fungi from the time of harvesting to arrival at an export destination.  相似文献   
44.
Nationwide seroprevalence of Neospora caninum among dairy cattle in Japan   总被引:3,自引:0,他引:3  
Serum samples from 2420 clinically healthy dairy cattle, randomly selected from stored sera in 18 districts of Japan, were tested for the presence of Neospora caninum antibodies using an indirect fluorescent antibody test (titer > or =1:200). Nationwide seroprevalence is estimated at 5.7% (139/2420). Seropositive cattle were detected in all surveyed districts despite the evidence of confirmed case reports of bovine neosporosis, showing that N. caninum is widely distributed throughout Japan. Age-specific seroprevalence did not increase with cattle age, suggesting that Neospora infection is likely to be transmitted vertically rather than horizontally in Japan. Considering that N. caninum seropositive cows are thought to be more likely to abort, substantial fetal losses may be induced by N. caninum infection in Japan. Devising strategies are needed to reduce the economic impact on the Japanese dairy industry. This is the first study to investigate the nationwide seroprevalence of N. caninum in cattle in Asia.  相似文献   
45.
抗战时期,桂林的抗战文化运动蓬勃发展,被誉为“文化城”。荟萃桂林的现代作家在中国共产党领导和文协桂林分会的推动下,众志成城,使得桂林的抗战文学创作空前繁荣,创作了一大批思想和艺术较高、影响较大的优秀文学作品,大大地丰富了我国现代文学宝库,在中国新文学史上写下了光辉的一页。  相似文献   
46.
详细介绍了东京大田农产品批发市场和名古屋批发市场在果菜、水产、花卉方面的交易情况,并对日本批发市场的设置程序和交易原则进行了简要阐述,最后提出发展中国批发市场的几点建议。  相似文献   
47.
该文从营养液栽培的发展规模、投资费用、营养液栽培方式等方面介绍了日本营养液栽培的现状、存在的问题及发展方向。在营养液管理方面,已发现单纯依靠检测电导率EC值控制营养液浓度的弊端,提出应针对各种离子的营养液浓度进行管理;各种废液的处理方法和营养液循环利用中去除病原菌和生长阻害物质的方法。分析了各种方法的利弊。最后该文详细介绍了日本营养液栽培的新技术——移动栽培和营养液土耕的基本原理,主要方法和效果。  相似文献   
48.
We investigated the extent of raccoon dog roadkills, and the factors influencing them, using data from the National Expressways in Japan for 1987-1998. A high rate of raccoon dog roadkills occurred in western Japan, whereas a relatively low rate was typical of the central region and of Hokkaido. Kills on the National Expressways increased as traffic and the length of the road network increased between 1987 and 1998. The relationship between mortality and traffic volume was scale-dependent. The number of roadkills was positively correlated with traffic volume at national level, but negatively correlated with the amount of traffic along sections of an individual major road between exits. There were spring and autumn peaks, and possibly early morning and evening peaks, of mortality. Mortality was higher for roads in a cutting, where the road was closer to water, and where the roadside habitat was broad-leaved woodland. Coniferous forest was negatively associated with roadkills. The total numbers of roadkills on four types of roads (National Expressways, National, Prefectural, and Municipal roads), was estimated to be between 110,000 and 370,000 in 1998. We suggest some preventative measures which might mitigate road casualties (while remaining attentive to human safety). Roadkill data, after controlling for traffic volume, can be useful as a population trend index. Patterns for racoon dogs are compared with those for other species.  相似文献   
49.
日本检疫性贸易壁垒及我应对措施   总被引:1,自引:0,他引:1  
通过对日本检疫性贸易壁垒的分析,我们应根据SPS协议的有关规定,采取必要措施,打破其检疫性贸易壁垒,促进我产品出口。  相似文献   
50.
Modern and historical Japanese societies are and were quite comfortable with a nature defined, designed, and dominated by humans. While contemporary Japanese are concerned about the environment, especially about non-timber (green) forest resources, conservation organizations are generally small and locally focused. Public forests, accounting for 40 percent of all Japan's forests, are intensively managed. At the national level, the timber program is operating below cost and there is increasing emphasis on non-timber management and rural economic development. A professional elite largely determines forest management goals and cultural barriers minimize broad public participation. Increasingly aware of the environmental impacts of their industrial society at home and abroad, the Japanese are becoming more environmentally concerned. Government agencies are especially proactive in enhancing environmental understanding among Japanese citizens and in sharing their resource management expertise with other Pacific Rim nations.  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