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   83486篇
  免费   4574篇
  国内免费   5485篇
林业   10283篇
农学   5922篇
基础科学   4202篇
  11541篇
综合类   42717篇
农作物   3363篇
水产渔业   2261篇
畜牧兽医   7065篇
园艺   2031篇
植物保护   4160篇
  2024年   258篇
  2023年   1208篇
  2022年   1807篇
  2021年   1884篇
  2020年   1845篇
  2019年   2356篇
  2018年   1327篇
  2017年   2560篇
  2016年   3275篇
  2015年   2943篇
  2014年   4151篇
  2013年   4199篇
  2012年   6207篇
  2011年   6633篇
  2010年   5435篇
  2009年   5312篇
  2008年   4872篇
  2007年   5744篇
  2006年   5008篇
  2005年   4130篇
  2004年   3129篇
  2003年   2711篇
  2002年   2083篇
  2001年   1835篇
  2000年   1681篇
  1999年   1325篇
  1998年   1160篇
  1997年   1059篇
  1996年   1051篇
  1995年   1008篇
  1994年   969篇
  1993年   829篇
  1992年   771篇
  1991年   642篇
  1990年   579篇
  1989年   520篇
  1988年   404篇
  1987年   276篇
  1986年   133篇
  1985年   47篇
  1984年   24篇
  1983年   23篇
  1982年   19篇
  1981年   19篇
  1980年   22篇
  1979年   16篇
  1978年   15篇
  1976年   10篇
  1962年   7篇
  1955年   7篇
排序方式: 共有10000条查询结果,搜索用时 18 毫秒
991.
992.
By review of region study in recent development of history science, geography and Sciences of Human Settlements, this paper points out that material collecting without interrelated analyzing as well as focusing on main question and assumption without enough argumentation are main problems in this field now. The method renovation & combination with related subjects are discussed, this paper concludes that strengthen interdisciplinary study with Geography is a key issue in the future development of region study in Sciences of Human Settlements and possible approach to "technical development' and "humanity concern'.  相似文献   
993.
The modernization has been the dream that Chinese nation has wished eagerly to realize all the time. In some sense, the modernization of China means urbanization. The reform and opening - up over the past 20 years , built and made the enormous achievement in urbanization of China, have changed the appearance of the city of China greatly. But to numerous traditional historical zones, what kind of urbanization way should on earth be taken, it has been the question long - term in dispute of the planning circles all the time. In this paper, Ciqikou community of Chongqing as an example, doing some discussions from sociology on this question, the author hopes, that for such difficult problem, by this settlement a piece of breach can be found as soon as possible.  相似文献   
994.
995.
Application system generally refers to all kinds of computer information system. It aims at improving the sharing and application of the resource. The resource in application system usually means data resource. For computer management and maintenance, there are not only data resource, but also program resource and network resource. Effective management of this resource is key to ensure proper work of the application system. In this paper, the basic pattern and policy for resource management is put forward and a method to build and realize the resource layer that lies between database layer and application layer is to be found. This management layer, which skillfully connects the application system with resource and establishes good base for application and exploitation of system, is named as resource management system.  相似文献   
996.
The living environment is becoming more and more important,one of the main elements which affect it is noises.This paper takes the Zhonghuafang for example,to research how the whole planning and the designing for the living district affect the control of noises.Applying architectural technology,in order to cut down noises,a sound screen around the site is made and the distinctive constitution for the buildings is designed.The methods of disposing noises are proposed to make sure that the residents of the advanced living district are content with the living environment.  相似文献   
997.
The conservation of historic buildings and their environment is an unavoidable problem in urban construction. In this paper, the authors give a few new thoughts about the problem. First, the historic buildings are important part of the core power in city competition.Second,the conservation work should be combined with their development. Third, a classified and multilevel system of protection and reuse of old buildings should be set up.  相似文献   
998.
Economics.Through sampling investigation and analysis on inhabitant domestic tap water consumption situation,it is given that economic factors are the main factors influence inhatitant's water consumption.The functional relations among inhabitant's income and water consumption,water price and consumption are given. The tap water's income elasticity of demand and price elasticity of demand is analyzed, along with the fluctuating range month by month of inhabitant's water consumption.Finally ,this paper offers the reference data for planning the ability of water supply and making policies of ladder water prices.  相似文献   
999.
The Lexicographic method has subjective and empirical character,so a weighting coefficient is introduced by considering the importance and proportion of each individual object,the preferable result of every individual object can be confirmed by comparing the degree of similarity between the perfect one and the ecumenic one and the Fuzzy optimization will be perfect.The effectiveness of these methods is illustrated by a fuzzy optimal design of the three-bar truss.  相似文献   
1000.
In this paper the problem of energy consumption and environment in the birdhouse is introduced and the reconstructive measures aiming at energy savings are recommended. The measures include the limitation of temperature region, reconstruction of the building envelop and using the sunny board at the south side of the birdhouse roof. Finally, the energy efficiency of the reconstructive project is estimated.  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