全文获取类型
收费全文 | 835篇 |
免费 | 42篇 |
专业分类
林业 | 55篇 |
农学 | 132篇 |
基础科学 | 22篇 |
157篇 | |
综合类 | 54篇 |
农作物 | 63篇 |
水产渔业 | 42篇 |
畜牧兽医 | 269篇 |
园艺 | 16篇 |
植物保护 | 67篇 |
出版年
2022年 | 6篇 |
2021年 | 14篇 |
2020年 | 24篇 |
2019年 | 17篇 |
2018年 | 21篇 |
2017年 | 33篇 |
2016年 | 25篇 |
2015年 | 19篇 |
2014年 | 23篇 |
2013年 | 57篇 |
2012年 | 44篇 |
2011年 | 42篇 |
2010年 | 30篇 |
2009年 | 31篇 |
2008年 | 32篇 |
2007年 | 28篇 |
2006年 | 22篇 |
2005年 | 25篇 |
2004年 | 12篇 |
2003年 | 16篇 |
2002年 | 24篇 |
2001年 | 21篇 |
2000年 | 12篇 |
1999年 | 12篇 |
1998年 | 11篇 |
1996年 | 7篇 |
1994年 | 11篇 |
1993年 | 6篇 |
1992年 | 11篇 |
1991年 | 9篇 |
1990年 | 11篇 |
1989年 | 9篇 |
1988年 | 17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 | 13篇 |
1980年 | 6篇 |
1979年 | 14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877条查询结果,搜索用时 15 毫秒
871.
Manmeet Kaur Amit Sharma Ravikant Gupta Yashpal Singh A. P. S. Sethi Chanchal Singh 《Tropical animal health and production》2017,49(8):1591-1596
Present study was conducted to assess the resource use efficiency of broilers production, in tunnel-ventilated environment control (ECBH) and open-sided conventional (OSCBH) house under different stocking densities. Different treatments comprised of T 0 (birds with floor space, 1.0/ft2/bird in open-sided conventional broiler house (OSCBH) as control, while different treatments in tunnel-ventilated environment control broiler house (ECBH) were T 1, T 2, T 3, T 4 and T 5 with floor space of 1.0, 0.9, 0.8, 0.7and 0.6 ft2 per bird, respectively. The results of shed microclimate indicated that shed temperature and temperature humidity index (THI) at 12:00 and 15:00 IST and maximum and minimum temperature in OSCBH were significantly (p ≤ 0.05) higher than ECBH. Litter moisture and pH did not differ significantly and were within permissible limits in both OSCBH and ECBH. Final body weight, body weight gain, feed intake were significantly higher and FCR, PER and EER were significantly better in ECBH than OSCBH (T 0) even at 10% increase in stocking density (T 2). Margin of receipt in T 2 in ECBH from sale of live bird/unit area and kilogram live weight per unit area was maximum which was Rs. 5.08/- and 3.56/- higher than T 0 for OSCBH. 相似文献
872.
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
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
873.
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
874.
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
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
875.
Amith R. Devireddy Madhuri A. Inupakutika David Willmon Prathusha Kakarla Naveen Puppala 《Acta Agriculturae Scandinavica, Section B - Plant Soil Science》2017,67(3):245-251
Antibiotics from various sources such as livestock waste are being accumulated in the soil. The excessive uptake of antimicrobial agents by plants has been a major concern as it is currently unknown how plants respond to the presence of antibiotics in agricultural lands. The objectives were to analyze the alteration of trigonelline (TRG) biosynthesized by plants in response to various antibiotic stresses and to evaluate the ability of peanut (Arachis hypogaea L.) plants to resist the deleterious impacts of antibiotic uptake. Three veterinary antibiotics used in this study were tetracycline, streptomycin sulfate, and chloramphenicol in the concentrations of 2.5 and 5 mg L?1. Mean TRG amounts were 53.4 ± 1.6 and 59.9 ± 1.1 μg·g?1 dry weight (DW) in Spanish as treated with growth chloramphenicol and streptomycin at 2.5 mg·L?1, respectively, and were significantly (p ≤ .05) different compared to the control (40.4 ± 1.6 μg·g?1 DW) of Spanish. Spanish genotype treated with chloramphenicol at 5 mg·L?1 had a mean TRG amount of 41.0 ± 1.0 μg·g?1 DW and improved yield, with the average pod number of 29.6 ± 7.6 and pod weight of 20.1 ± 6.1 g. TRG was continuously biosynthesized and increased under antibiotic stress up to 12.7% at full pod (R4 growth stage) and 139.1% at beginning maturity (R7), but declined 20.2% at the harvest stage (R8) in all combined genotypes when compared with TRG amounts (21.7 ± 0.6 μg·g?1 DW) at the flowering R1 stage. 相似文献
876.
逆境胁迫下的农业管理中土壤-植物-微生物相互作用研究进展 总被引:2,自引:0,他引:2
The expected rise in temperature and decreased precipitation owing to climate change and unabated anthropogenic activities add complexity and uncertainty to agro-industry.The impact of soil nutrient imbalance,mismanaged use of chemicals,high temperature,flood or drought,soil salinity,and heavy metal pollutions,with regard to food security,is increasingly being explored worldwide.This review describes the role of soil-plant-microbe interactions along with organic manure in solving stressed agriculture problems.Beneficial microbes associated with plants are known to stimulate plant growth and enhance plant resistance to biotic (diseases) and abiotic (salinity,drought,pollutions,etc.) stresses.The plant growth-promoting rhizobacteria (PGPR) and mycorrhizae,a key component of soil microbiota,could play vital roles in the maintenance of plant fitness and soil health under stressed environments.The application of organic manure as a soil conditioner to stressed soils along with suitable microbial strains could further enhance the plant-microbe associations and increase the crop yield.A combination of plant,stress-tolerant microbe,and organic amendment represents the tripartite association to offer a favourable environment to the proliferation of beneficial rhizosphere microbes that in turn enhance the plant growth performance in disturbed agro-ecosystem.Agriculture land use patterns with the proper exploitation of plant-microbe associations,with compatible beneficial microbial agents,could be one of the most effective strategies in the management of the concerned agriculture lands owing to climate change resilience.However,the association of such microbes with plants for stressed agriculture management still needs to be explored in greater depth. 相似文献
877.