全文获取类型
收费全文 | 6830篇 |
免费 | 238篇 |
国内免费 | 195篇 |
专业分类
林业 | 540篇 |
农学 | 350篇 |
基础科学 | 258篇 |
285篇 | |
综合类 | 4862篇 |
农作物 | 153篇 |
水产渔业 | 99篇 |
畜牧兽医 | 336篇 |
园艺 | 270篇 |
植物保护 | 110篇 |
出版年
2024年 | 25篇 |
2023年 | 77篇 |
2022年 | 88篇 |
2021年 | 113篇 |
2020年 | 105篇 |
2019年 | 133篇 |
2018年 | 46篇 |
2017年 | 149篇 |
2016年 | 211篇 |
2015年 | 277篇 |
2014年 | 364篇 |
2013年 | 351篇 |
2012年 | 635篇 |
2011年 | 788篇 |
2010年 | 607篇 |
2009年 | 583篇 |
2008年 | 545篇 |
2007年 | 596篇 |
2006年 | 401篇 |
2005年 | 289篇 |
2004年 | 162篇 |
2003年 | 137篇 |
2002年 | 87篇 |
2001年 | 79篇 |
2000年 | 57篇 |
1999年 | 51篇 |
1998年 | 39篇 |
1997年 | 37篇 |
1996年 | 36篇 |
1995年 | 35篇 |
1994年 | 31篇 |
1993年 | 19篇 |
1992年 | 21篇 |
1991年 | 30篇 |
1990年 | 18篇 |
1989年 | 10篇 |
1988年 | 8篇 |
1987年 | 7篇 |
1986年 | 4篇 |
1985年 | 4篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1979年 | 1篇 |
1975年 | 1篇 |
排序方式: 共有7263条查询结果,搜索用时 15 毫秒
51.
目前农村老年人养老现状不容乐观.家庭养老功能弱化,社区养老机制滞后,社会福利、政府救济和低保投入严重不足等,导致绝大多数农村老年人处在家庭边缘和社会保障体系之外. 相似文献
52.
本文介绍一种用于分离检测土壤中棉枯萎病菌的选择性培养基—植选2号。其成分为:KH_2PO_41g,MgSO_4·7H_2O 0.5g,K_2S_2O_50.2g,KCl0.6g,NH_4NO_3 0.5g,蛋白胨5g,山梨糖10g,蔗糖5g,琼脂20g,蒸馏水1000ml,PCNB 620mg,Oxgall1g,硫酸链霉素300mg,盐酸金霉素75mg。根据棉枯萎病在此培养基上的形态特征,能较容易地识别和检测该病菌。 相似文献
53.
农民负担实际上是与农民有关的公共产品成本的分摊,而这种分摊存在着体制缺陷,这种缺陷导致了农民的生产效益低下,农民负担逐步加重。要改变这种现状就必须对农村公共产品供给体制进行改革和完善,以期从根本上减轻农民负担。 相似文献
54.
Employing the standpoint of irrational investors in the behavior finance, the authors study the relation on the irrational behavior of medium and small Investors and underpricing of IPO in our country. The paper premises that a revenue-maximizing issuer will be regarded as the target function, and the rational institutional investors can be delegated the task of holding the stocks in the after-market for resale to the irrational medium and small investors--thereby extracting surplus from them, finally the issuer can maximize their expected revenue. We model the process mentioned above and find that the high underpricing of IPO in our country has the direct relation with numerous the irrational medium and small investors existing in our country who cause the underpricing. 相似文献
55.
56.
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
57.
58.
对三农问题和农村城市化问题的若干思考 总被引:1,自引:0,他引:1
中国是一个农业大国,农业经济状况在很大程度上决定了整体经济的发展态势。对中国当前农业发展现状中的主要问题进行分析,认为只有积极进行城市化建设才能解决中国农业发展的根本问题,同时,就中国城市化的路径选择与城市化发展的中短期目标提出自己的看法。 相似文献
59.
The organization of two farmer-managed irrigation systems in the western hills of Nepal is described by examining the ways in which the activities of water allocation, water distribution, maintenance, and resource mobilization are performed. Due to the topography and environment, these two organizations are structured primarily to mobilize the large amount of labor required for maintenance of the intake and canal. Both organizations precisely define each member's water allocation. In one system, water is allocated in proportion to the area of an individual's land holding, while in the other water allocation is by purchased shares. These two cases were used to analyze the importance of the principle of water allocation for expansion of area irrigated and equity of access to irrigation. Evidence from the two systems shows that in this hill environment water allocation by purchased shares provides the individual incentive and an organizational mechanism for efficient development of irrigation resources. Expansion of area irrigated and equity of access to irrigation were found to be greater in the system which allocates water by purchased shares than where water was allocated in proportion to area irrigated. 相似文献
60.
介绍了江苏省农机作业组织基本特点与启示.阐述了农机作业组织重要性与发展机遇、发展农机作业组织重点和原则,提出了3项推进农机作业组织发展政策与措施。 相似文献