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   7659篇
  免费   381篇
  国内免费   233篇
林业   1540篇
农学   441篇
基础科学   470篇
  815篇
综合类   4296篇
农作物   104篇
水产渔业   40篇
畜牧兽医   355篇
园艺   104篇
植物保护   108篇
  2024年   29篇
  2023年   83篇
  2022年   88篇
  2021年   151篇
  2020年   167篇
  2019年   181篇
  2018年   72篇
  2017年   141篇
  2016年   221篇
  2015年   214篇
  2014年   434篇
  2013年   385篇
  2012年   821篇
  2011年   800篇
  2010年   607篇
  2009年   593篇
  2008年   580篇
  2007年   638篇
  2006年   470篇
  2005年   321篇
  2004年   253篇
  2003年   259篇
  2002年   207篇
  2001年   144篇
  2000年   133篇
  1999年   66篇
  1998年   51篇
  1997年   40篇
  1996年   29篇
  1995年   21篇
  1994年   23篇
  1993年   14篇
  1992年   14篇
  1991年   3篇
  1990年   5篇
  1989年   8篇
  1988年   2篇
  1987年   3篇
  1986年   1篇
  1981年   1篇
排序方式: 共有8273条查询结果,搜索用时 156 毫秒
101.
The authors discuss such questions for utility boiler as the complicated flameworks,combined quoting course, long cycle, hardly controlling the quoting veracity and so on. Based on the construction diagram of quoting design for utility boiler, Which is into the boiler sketch's construction and parameter characteristic. They are furnace construction, big screen superheater, high temperature superheater, low temperature superheater, high temperature reheater, low temperature reheater, economy coal implement, common use sign and standard sketch in boiler sketch, etc. According to demand of the quote design for utility boiler, the CAD environment of quoting system based on characteristic construction and parameter are developed. Total construction of this environment , developing characteristics and function of this system are given.  相似文献   
102.
The society-economy-environment appraisal for construction project can help our government to control macro-economy, make correlation policy and formulate laws and draw up city plan.It has great influence on the sustainable development of our society and it is the demand of the law for the environment evaluation in China.This paper introduced the basic structure of society-economy-environment appraisal system for construction project and the thought of elements transaction.Using the method of AHP, the model of project analyzing and optimizing selection is designed.For the more, the methods of the optimizing models on the selected schemes are put forward.Finally, the integrative analysis has been made on the system design and appliance of this appraisal system.  相似文献   
103.
In accordance with the special characteristics of state medium-sized construction enterprises and their reform objects of "having a free hand and enlivening", the suitable objective model, the stock cooperative system for state medium-sized construction enterprises has been put forward in this paper by analyzing the system mechanism of stock cooperative system enterprises. Then the causes for it were expounded.  相似文献   
104.
This paper presents some problems that is important part of the desision supportsystem on science-technic progress management at the construction enterprise and discusses targetsystems and evaluation models of synthesis effects on science-technic grogress at the sonstruction en-terprise,and some problem are illustrated and analysed further.  相似文献   
105.
106.
107.
Construction and relative service is one of the important categories in international service trade set down by WTO. In order to strike a construction agreement, the developed countries and districts have designed a lot of prevailing standard treaty wording, in which FIDIC plays the most important part. We should take advantages of their experience to improve our standard treaty wording.  相似文献   
108.
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   
109.
Construction industry is not only the pillar industry in national economy,but also the typical industry with intensive labors.As a major part of the construction industry,the Construction Employment System(CES) is an important factor of the market order,as well as the quality,the safety and the development of the industry.It is also an important part for building a harmonious society.It concerns the social harmony,political harmony,societal harmony,cultural harmony,urban-rural harmony,etc.However,at present,there are still many problems in CES that might influence the harmonious society building.This paper advises to speed up the reformation of CES,to establish and consummate the system of construction labor subcontract,to develop vigorously labor subcontract corporations,to improve the quality of the labors,to ensure the rights and interests of the labor.  相似文献   
110.
The agent - construction system, as a new public project management mode, has been practiced in some cities and attracted attention from the society. This paper firstly studies the features and operation modes of agent - construction system, and discusses the agent - construction system from the viewpoints of promoting competition, nourishing agent -construction enterprises, setting up a supervisory and encouraging mechanism, and its connection with the governmental project procurement system etc.  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