全文获取类型
收费全文 | 5743篇 |
免费 | 348篇 |
国内免费 | 480篇 |
专业分类
林业 | 445篇 |
农学 | 387篇 |
基础科学 | 225篇 |
481篇 | |
综合类 | 2855篇 |
农作物 | 470篇 |
水产渔业 | 304篇 |
畜牧兽医 | 809篇 |
园艺 | 416篇 |
植物保护 | 179篇 |
出版年
2024年 | 34篇 |
2023年 | 103篇 |
2022年 | 237篇 |
2021年 | 217篇 |
2020年 | 220篇 |
2019年 | 225篇 |
2018年 | 147篇 |
2017年 | 249篇 |
2016年 | 152篇 |
2015年 | 259篇 |
2014年 | 275篇 |
2013年 | 356篇 |
2012年 | 492篇 |
2011年 | 577篇 |
2010年 | 502篇 |
2009年 | 500篇 |
2008年 | 492篇 |
2007年 | 409篇 |
2006年 | 300篇 |
2005年 | 272篇 |
2004年 | 163篇 |
2003年 | 94篇 |
2002年 | 100篇 |
2001年 | 83篇 |
2000年 | 74篇 |
1999年 | 24篇 |
1998年 | 3篇 |
1997年 | 4篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1988年 | 1篇 |
1981年 | 1篇 |
1979年 | 1篇 |
1955年 | 1篇 |
排序方式: 共有6571条查询结果,搜索用时 31 毫秒
31.
针对石羊河流域水资源缺乏、种植业生产受限的问题,比较了武威市凉州区19种种植模式的水资源利用效率。结果表明,马铃薯和油葵较春小麦(CK1)节水25%且分别增收84.21%和31.58%;低耗水型模式玉米/豌豆和油葵/豌豆的水分利用效率较传统模式春小麦/春玉米(CK2)提高38.2%和52.9%,水分经济利用效率提高51.6%和125%,水分能量生产效率提高40.72%和49.81%;日光温室中,辣椒、西瓜和双孢菇的节水增收效果较好。由此提出发展马铃薯、油葵等低耗水高效模式,以玉米/豌豆、油葵/豌豆替代高耗水型模式春小麦/春玉米,日光温室重点发展辣椒、西瓜和双孢菇等作物的建议。 相似文献
32.
为了探讨玉米不同自交系对UV-B辐射增强的响应,在摸拟光照培养条件下,研究了增强UV-B辐射对玉米不同自交系气体交换参数的影响。结果表明,五叶期UV-B辐射处理6 d后,供试的48个自交系中近一半以上材料的幼苗叶片光合速率、气孔导度和蒸腾速率显著降低10%以上,其材料比例分别为64.6%,47.9%,54.2%;而有62.5%的材料胞间CO2浓度表现为显著增加;相关分析发现,气孔导度与蒸腾速率对UV-B辐射增强的响应值间存在极显著正相关关系;根据气体交换参数对UV-B辐射增强的响应程度将48个材料分成6类,其中对增强UV-B辐射反应比较敏感的材料和能够忍耐UV-B辐射增强的材料均占12.5%。说明玉米不同自交系幼苗叶片气体交换参数对UV-B辐射增强反应敏感程度具有显著的基因型差异,从中能够筛选出对UV-B辐射增强反应敏感和有忍耐能力的材料。 相似文献
33.
介绍了猪的生物学特性和猪的养殖技术,调查了近2年来江西省新余市生猪的养殖现状,分析了生猪养殖存在的问题,并提出相应对策。 相似文献
34.
本试验对三江源区不同高寒草地植物中6种矿物元素(钾K,钙Ca,钠Na,镁Mg,锌Zn,铁Fe)的含量进行了测定和分析,结果表明:植物中K元素含量为7.314~12.803 g·kg-1之间,Ca元素含量为2.851~6.823 g·kg-1之间,Na元素含量为64.404~185.553 mg·kg-1之间,Mg元素含量为1.272~2.655 g·kg-1之间,Zn元素含量为14.718~51.387 mg·kg-1之间,Fe元素含量为161.056~531.677 mg·kg-1之间;豆科(Leguminosae)植物和杂类草(Forbs)矿物元素含量显著高于禾本科(Gramineae)和莎草科(Cyperaceae)植物;植物中K元素与Mg元素、Ca元素与Na元素、Ca元素与Zn元素、Na元素与Zn元素含量之间呈极显著正相关关系(P<0.01),Ca元素与Fe元素、Mg元素与Fe元素之间呈显著正相关关系(P<0.05);根据美国国家研究理事会(National research council,NRC)绵羊日粮矿物元素需求标准,三江源区各草地植物中Na,Zn元素相对缺乏,其它4种元素均能满足放牧藏羊的矿物营养需求。 相似文献
35.
GAO Feng HE Jian-bin ZHANG Yi LONG Miao LI Lin LI Yan-peng HAN Yang WANG Xue JIANG Li-ying YANG Shu-hua 《中国畜牧兽医》2016,43(2):471-476
The study was aimed to explore the protective effect of sulforaphane (SFN) on the reproductive function of male mice with cadmium poisoning.40 healthy clean grade male Kunming mice were randomly divided into four groups:control group (H2O),cadmium chloride group (2.3 mg/kg CdCl2),sulforaphane group (10 mg/kg SFN),sulforaphane + cadmium chloride group (10 mg/kg SFN+2.3 mg/kg CdCl2),and continuous administration for 10 d,all mice were executed by dislocated cervical vertebra at 2 d after the last administration,and then the pathologic changes of testicular tissues,organ coefficient of testicle and epididymis,sperm quality and concentration of testosterone were tested.Additionally,the contents of GSH and MDA,and the activities of T-SOD in testis were also detected at the same time. Compared with the control group,pathology damages were observed in cadmium chloride group,organ coefficient of testis and epididymis,sperm quality and levels of testosterone extremely significantly decreased (P<0.01),the activities of T-SOD and GSH content were extremely significantly decreased (P<0.01),and the concentration of MDA was extremely significantly enhanced (P<0.01).Compared with the control group,the activity of T-SOD and concentration of GSH in sulforaphane group were significantly increased (P<0.05),and the concentration of MDA was not significant different between the control group and sulforaphane group (P>0.05).While compared with the cadmium chloride group,the sperm motility rate and sperm total count in sulforaphane and cadmium chloride group were extremely significantly increased (P<0.01),the organ coefficient of testicle and epididymis was increased significantly (P<0.05),the concentration of GSH and activity of T-SOD in testicular tissue were extremely significantly increased (P<0.01),and the concentration of MDA was extremely significantly decreased (P<0.01).The results indicated that sulforaphane had the protection effect on reproduction function of male mice with cadmium poisoning. 相似文献
36.
37.
38.
The establishment of the competition legal system is the response to the social and economical reality. The perfection of the competition legal system needs the support of economic theory. Therefore, analyzing the competition from the law and economic perspective is propitious to perfect the regulation of competition in the law system constantly, guarantee and promote competition, and thus to establish and maintain reasonable and efficient competition order, promote market-economy developing prosperously and harmoniously. The paper uses the study methods of economical and comparative analyze, explore the sorts of competition and their effectiveness, believe that the perfection of the competition legal system should firstly definite that its adjust object is the effective competition with monopoly factor; though the exemption of competition cant be avoid, it continuously appears shrinking trend. The competition legal system will play a more important role in the economical life. 相似文献
39.
The traditional scheduling for vehicle is option in the fixed network. But it can't satisfy the real time environment. The demand of order is changeable and uncertain in real environment. It is convenient for scheduling transforming it into static data, but can't get the advantage on time. This paper proposes a real time vehicle scheduling on the study of traditional scheduling and discusses the model structure and the key technology for the real time system that establishes the base for develop teal time system. 相似文献
40.
JING Li-ying 《保鲜与加工》2006,(3):156-158
Owning to the ability of accepting insurance enough,it is the foundation for insurance companies to operate in a long-term and steady way,a method to develop sustainably,a reflection of an insurance company's comprehensive competition ability and also a premise for an insurance company to realize developing strategy.Accepting insurance ability is very important in the development and strategic planning for an insurance company.The quantitative analysis is used to analyze the ability of accepting insurance of our country's insurance companies,in another word,the factor(analysis),which belongs to the analysis of diverse statistic,is used.Using the method to give a concrete evidence analysis to the ability of accepting insurance of our country's non-life insurance companies,so that the insurance companies can understand very well to the advantages and disadvantages of the ability of accepting insurance to each other,and as well as supplying a strategic reference for the insurance companies themselves to make decisive planning. 相似文献