全文获取类型
收费全文 | 867篇 |
免费 | 47篇 |
专业分类
林业 | 55篇 |
农学 | 131篇 |
基础科学 | 23篇 |
173篇 | |
综合类 | 55篇 |
农作物 | 69篇 |
水产渔业 | 39篇 |
畜牧兽医 | 280篇 |
园艺 | 11篇 |
植物保护 | 78篇 |
出版年
2021年 | 14篇 |
2020年 | 23篇 |
2019年 | 15篇 |
2018年 | 19篇 |
2017年 | 30篇 |
2016年 | 28篇 |
2015年 | 24篇 |
2014年 | 22篇 |
2013年 | 56篇 |
2012年 | 44篇 |
2011年 | 42篇 |
2010年 | 32篇 |
2009年 | 32篇 |
2008年 | 40篇 |
2007年 | 28篇 |
2006年 | 25篇 |
2005年 | 30篇 |
2004年 | 13篇 |
2003年 | 20篇 |
2002年 | 27篇 |
2001年 | 20篇 |
2000年 | 14篇 |
1999年 | 13篇 |
1998年 | 11篇 |
1996年 | 8篇 |
1995年 | 7篇 |
1994年 | 11篇 |
1993年 | 7篇 |
1992年 | 11篇 |
1991年 | 9篇 |
1990年 | 11篇 |
1989年 | 9篇 |
1988年 | 18篇 |
1987年 | 18篇 |
1986年 | 11篇 |
1985年 | 7篇 |
1984年 | 9篇 |
1983年 | 11篇 |
1982年 | 9篇 |
1981年 | 14篇 |
1980年 | 6篇 |
1979年 | 15篇 |
1978年 | 8篇 |
1975年 | 13篇 |
1973年 | 8篇 |
1972年 | 6篇 |
1971年 | 7篇 |
1970年 | 11篇 |
1969年 | 13篇 |
1968年 | 6篇 |
排序方式: 共有914条查询结果,搜索用时 62 毫秒
911.
Polymorphism in 5′ untranslated region of heat‐shock protein 70 gene as marker of post‐partum anoestrus in Murrah buffaloes
下载免费PDF全文
![点击此处可从《Reproduction in domestic animals》网站下载免费的PDF全文](/ch/ext_images/free.gif)
R Kumar M Ghosh N Kumar AK Balhara M Gupta RK Sharma I Singh 《Reproduction in domestic animals》2017,52(3):505-512
The enormous production potential of buffaloes has never been accomplished due to various reproductive insufficiencies. Among them, post‐partum anoestrus, a multifactorial disorder, is predominant but any genetic association is yet to be established. This study focused to identify novel polymorphisms in heat‐shock protein 70 (HSP70) gene and its possible association with post‐partum anoestrus in Murrah buffaloes. A 579‐bp fragment from 5′ untranslated region of HSP70 gene was amplified by polymerase chain reaction from blood genomic DNA of 614 animals maintained under similar management conditions. In phase‐I experiment, custom sequencing and restriction enzyme (RE) digestion of the amplified fragment were performed in 40 buffaloes with similar post‐partum oestrous conditions over previous consecutive three or more gestations—20 animals each showing post‐partum anoestrus (>120 days after parturition) and normal cyclicity (<65 days after parturition). While in phase‐II experiment, herd screening by RE analysis was performed in remaining 574 animals. Four transversions at T‐75G, C+31G, T+38G and C+97A and three transition mutations at T‐153C, T+33C and A+44G positions were observed. Polymorphism at T+38G site revealed significant (p < .05) variation, where homozygous G was present only in post‐partum anoestrous animals while nucleotide T was present randomly in both groups of phase‐I animals whereas phase‐II experiments revealed homozygous G in 55 animals. Regression analysis in relation to average post‐partum interval against genotypic frequencies at T+38G also depicted significant association. HSP70 gene polymorphism at T+38G position can therefore be used as genetic marker for excluding probable post‐partum anoestrous buffaloes from herd for breeding programmes. 相似文献
912.
Rajiv Pandey Roberta Aretano Ajay K. Gupta Dhanraj Meena Bhuvnesh Kumar Juha M. Alatalo 《Small-Scale Forestry》2017,16(1):53-63
Climate change is expected to increase temperatures and rainfall in the Himalayan region and place stress on local livelihoods by affecting agro-biodiversity, crop yield, cropping patterns and the species composition of forests. This paper reports findings of a survey of farmers into the role of agroforestry or ‘agroecological intensification’ for reducing climate change vulnerability. The survey was conducted in the Tehri-Garhwal district of Uttarakhand, a Himalayan State of India. Existing traditional agroforestry was found to provide ecosystem services to farmers at various scales ranging from the global to household level, contributing to the livelihoods and resilience of the farmers to climate change. The strategies of farmers for adaptating to climate change include adoption of agroforestry due to its diversified agricultural and forest products and services. The analysis suggests that policies should consider agroforestry as a tool for improving the livelihood and resilience to climate change of farmers. 相似文献
913.
Soil organic carbon changes after seven years of conservation agriculture in a rice–wheat system of the eastern Indo‐Gangetic Plains
下载免费PDF全文
![点击此处可从《Soil Use and Management》网站下载免费的PDF全文](/ch/ext_images/free.gif)
T. B. Sapkota R. K. Jat R. G. Singh M. L. Jat C. M. Stirling M. K. Jat D. Bijarniya M. Kumar Yadvinder‐Singh Y. S. Saharawat R. K. Gupta 《Soil Use and Management》2017,33(1):81-89
Sequestration of soil organic carbon (SOC) is an important strategy to improve soil quality and to mitigate climate change. To investigate changes in SOC under conservation agriculture (CA), we measured SOC concentrations after seven years of rice (Oryza sativa L.)–wheat (Triticum aestivum L.) rotations in the eastern Indo‐Gangetic Plains (IGP) of India under various combinations of tillage and crop establishment methods. The six treatments were as follows: conventional till transplanted rice followed by conventional till wheat (CTR‐CTW), CTR followed by zero‐till wheat (CTR‐ZTW), ZT direct‐seeded rice followed by CTW (ZTDSR‐CTW), ZTDSR followed by ZT wheat both on permanent raised beds with residue (PBDSR‐PBW+R), and ZTDSR followed by ZTW both with (ZTDSR‐ZTW+R) and without residues (ZTDSR‐ZTW). We hypothesized that CA systems (i.e. ZT with residue retention) would sequester more carbon (C) than CT. After seven years, ZTDSR‐ZTW+R and PBDSR‐PBW+R increased SOC at 0–0.6 m depth by 4.7 and 3.0 t C/ha, respectively, whereas the CTR‐CTW system resulted in a decrease in SOC of 0.9 t C/ha. Over the same soil depth, ZT without residue retention (ZTDSR‐ZTW) only increased SOC by 1.1 t C/ha. There was no increase in SOC where ZT in either rice or wheat was followed by CT in the next crop (i.e. CTR‐ZTW and ZTDSR‐CTW), most likely because the benefit of ZT is lost when followed by tillage. Tillage and crop establishment methods had no significant effect on the SOC stock below the 0.15‐m soil layer. Over the seven years, the total carbon input from above‐ground residues was ca. 14.5 t/ha in ZTDSR‐ZTW+R and PBDSR‐PBW+R, almost sixfold greater than in the other systems. Our findings suggest that the increased biomass production achieved through a combination of ZT and partial residue retention offers an opportunity to increase SOC whilst allowing residues to be used for other purposes. 相似文献
914.