全文获取类型
收费全文 | 423篇 |
免费 | 17篇 |
国内免费 | 1篇 |
专业分类
林业 | 33篇 |
农学 | 26篇 |
基础科学 | 4篇 |
89篇 | |
综合类 | 31篇 |
农作物 | 29篇 |
水产渔业 | 24篇 |
畜牧兽医 | 146篇 |
园艺 | 11篇 |
植物保护 | 48篇 |
出版年
2023年 | 3篇 |
2022年 | 8篇 |
2021年 | 5篇 |
2020年 | 16篇 |
2019年 | 12篇 |
2018年 | 12篇 |
2017年 | 14篇 |
2016年 | 13篇 |
2015年 | 12篇 |
2014年 | 21篇 |
2013年 | 40篇 |
2012年 | 27篇 |
2011年 | 28篇 |
2010年 | 25篇 |
2009年 | 24篇 |
2008年 | 17篇 |
2007年 | 21篇 |
2006年 | 12篇 |
2005年 | 9篇 |
2004年 | 9篇 |
2003年 | 4篇 |
2002年 | 7篇 |
2001年 | 6篇 |
2000年 | 3篇 |
1999年 | 5篇 |
1997年 | 6篇 |
1996年 | 2篇 |
1995年 | 7篇 |
1994年 | 4篇 |
1992年 | 5篇 |
1991年 | 7篇 |
1990年 | 8篇 |
1989年 | 2篇 |
1987年 | 4篇 |
1985年 | 3篇 |
1984年 | 2篇 |
1983年 | 5篇 |
1981年 | 2篇 |
1979年 | 2篇 |
1977年 | 2篇 |
1976年 | 4篇 |
1975年 | 2篇 |
1974年 | 1篇 |
1972年 | 1篇 |
1970年 | 1篇 |
1969年 | 2篇 |
1968年 | 3篇 |
1967年 | 4篇 |
1966年 | 2篇 |
1965年 | 1篇 |
排序方式: 共有441条查询结果,搜索用时 15 毫秒
61.
Vishnu Sukumari Nath Muthukrishnan Senthil Vinayaka Mahabaleswar Hegde Muthulekshmi Lajapathy Jeeva Raj Shekhar Misra Syamala Swayamvaran Veena Mithun Raj 《European journal of plant pathology / European Foundation for Plant Pathology》2013,136(3):483-494
The oomycete Phytophthora colocasiae that causes taro leaf blight is the most devastating disease of taro and is widely distributed worldwide. Molecular and phenotypic techniques were employed for assessing and exploiting the genetic variability among four populations of P. colocasiae obtained from a fine spatial scale (multiple leaf blight lesions on single taro leaf). Phenotypic characters such as virulence, morphology and mating type showed no variation. ITS characterization revealed detectable polymorphism among isolates of P. colocasiae. The mean number of haplotypes (H), haplotype diversity (HD), nucleotide diversity (π), and nucleotide substitution rate (θ) among analyzed sequences were 6.75, 1.00, 0.069, and 0.088 respectively. High levels of inter and intra specific variation were detected by random amplified polymorphic DNA (RAPD) assays. Moderate genetic diversity (H?=?0.2651) was observed among populations of P. colocasiae. Analysis of molecular variance (AMOVA) confirmed that most of the genetic variability was confined to within a population (63.54 %). The coefficient of genetic differentiation among populations (G ST ) was 0.2007 and estimates of gene flow (Nm) among populations was 1.991 migrants per generation. Cluster analysis using UPGMA revealed that individuals from the same population failed to cluster in one distinct group. The results of the study reveal considerable genetic diversity among and within populations of P. colocasiae obtained from fine spatial scale. The possible mechanisms and implications of this genetic variation are discussed. 相似文献
62.
R. Raj Bhansali J. Driver D. J. Durzan 《The Journal of Horticultural Science and Biotechnology》2013,88(5):601-605
Cell suspension cultures were derived from adventitious somatic embryos induced on cotyledons of rescued peach embryos. Embryogénie calli were induced and established on modified MS medium supplemented with 2,4-D, BAP, KN and inositol. Development of embryos during suspension cultures was identified by growth pattern and by histological and cytological examination, using acetocarmine stain. More embryogenic calli were produced using 2,4-D (5 (µM) than NAA. A gradual reduction of 2,4-D increased the recovery of globular embryos. Heart-stage embryos were developed on high-nitrogen salt medium, with added Ca(N03)2 (1000 mg I"1) and 6% sucrose. Somatic embryos turned green and sometimes red under white light. Embryo viability was highest when subculturing every 14 days. Viability of cells and differentiating embryos was assessed, microscopically, with Alexander’s stain. Viable embryos reacted pink to red while non- viable embryos reacted green to blue. Embryogenic cell suspension cultures were maintained for over ten months by regular subculturing after two weeks on modified MS medium with low 2,4-D, BAP and KN. 相似文献
63.
Koppad S Raj GD Gopinath VP Kirubaharan JJ Thangavelu A Thiagarajan V 《Research in veterinary science》2011,91(3):384-390
Calcium phosphate (CaP) particles were coupled with inactivated Newcastle disease virus (NDV) vaccine. The surface morphology of CaP particles coupled to NDV was found to be spherical, smooth and with a tendency to agglomerate. The mean (± SE) size of CaP particles was found 557.44 ± 18.62 nm. The mean percent encapsulation efficiency of CaP particles coupled to NDV assessed based on total protein content and haemagglutination (HA) activity in eluate was found to be 10.72 ± 0.89 and 12.50 ± 2.09, respectively. The humoral and cell mediated immune responses induced by CaP coupled NDV vaccine were assessed in comparison to a commercial live vaccine (RDV ‘F’). CaP coupled NDV vaccine elicited prolonged haemagglutination inhibition (HI) and enzyme linked immunosorbent assay (ELISA) titres in the serum even at fourth and fifth week post-vaccination (PV), unlike RDV ‘F’ inoculated chickens whose titres declined to insignificant levels by this time. CaP coupled NDV vaccine could stimulate HI antibodies in tracheal washings and tears from second and first week PV, respectively. IgA ELISA antibodies were also seen in tracheal washings of these birds from third week PV and in tears from second week PV. CaP coupled NDV vaccine elicited cell mediated immune responses (CMI) from two to four weeks PV. The stimulation indices obtained after stimulation with specific antigen was not significantly different between CaP coupled antigen and live NDV virus except on first week PV. However, CaP coupled antigen did not cause suppression of lympo proliferation as indicated by statistically similar responses to mitogen, concanavalin A between the two groups. Overall, CaP coupled NDV vaccine elicited stronger and prolonged immune responses in comparison to the commercial live vaccine. No increase in the serum calcium and phosphorous levels were seen in CaP coupled NDV vaccine inoculated chickens. 相似文献
64.
65.
Ali Khammanivong Jhuma Saha Angela K. Spartz Brent S. Sorenson Alexander G. Bush Derek M. Korpela Raj Gopalakrishnan Shirisha Jonnalagadda Venkatram R. Mereddy Timothy D. O'Brien Lester R. Drewes Erin B. Dickerson 《Veterinary and comparative oncology》2020,18(3):324-341
Monocarboxylate transporters (MCTs) support tumour growth by regulating the transport of metabolites in the tumour microenvironment. High MCT1 or MCT4 expression is correlated with poor outcomes in human patients with head and neck squamous cell carcinoma (HNSCC). Recently, drugs targeting these transporters have been developed and may prove to be an effective treatment strategy for HNSCC. Feline oral squamous cell carcinoma (OSCC) is an aggressive and treatment‐resistant malignancy resembling advanced or recurrent HNSCC. The goals of this study were to investigate the effects of a previously characterized dual MCT1 and MCT4 inhibitor, MD‐1, in OSCC as a novel treatment approach for feline oral cancer. We also sought to determine the potential of feline OSCC as a large animal model for the further development of MCT inhibitors to treat human HNSCC. In vitro, MD‐1 reduced the viability of feline OSCC and human HNSCC cell lines, altered glycolytic and mitochondrial metabolism and synergized with platinum‐based chemotherapies. While MD‐1 treatment increased lactate concentrations in an HNSCC cell line, the inhibitor failed to alter lactate levels in feline OSCC cells, suggesting an MCT‐independent activity. In vivo, MD‐1 significantly inhibited tumour growth in a subcutaneous xenograft model and prolonged overall survival in an orthotopic model of feline OSCC. Our results show that MD‐1 may be an effective therapy for the treatment of feline oral cancer. Our findings also support the further investigation of feline OSCC as a large animal model to inform the development of MCT inhibitors and future clinical studies in human HNSCC. 相似文献
66.
Anjali Thakur Raj Paul Sharma Narender Kumar Sankhyan Swapana Sepehya 《Soil Use and Management》2023,39(1):357-367
Imbalanced fertilizer use with intensive cropping has threatened the sustainability of agroecosystems, especially on acid soils. An understanding of the long-term effects of fertilizers and amendments on soil health is essential for sustaining high crop yields. The effects of application of fertilizers, and amendments for 46 years on soil properties and maize yield in an acid Alfisol were investigated in this study. Ten fertilizer treatments comprising different amounts of NPK fertilizers, farmyard manure (FYM) and lime, and one control, were replicated three times in a randomized block design. At 0–15 cm soil depth, bulk density was least (1.20 t/m3), porosity (49.8%) and water holding capacity (61.7%) were greatest in 100% NPK + FYM, corresponding to the largest organic carbon content (13.93 g/kg). Microbial biomass C and dehydrogenase activity in 100% NPK + FYM were 42% and 13.7% greater than 100% NPK, respectively. Available nutrients were significantly more with 100% NPK + FYM and 100% NPK + lime than control and other fertilizer treatments. At 15–30 cm depth, the effect of various treatments was comparable to the surface layer. Grain yield declined by 55% and 53% in 100% NPK(-S) and 100% NP, respectively, compared with 100% NPK, whereas 100% N as urea alone eventually led to crop failure. Soil porosity recorded the greatest positive correlation (r = .933**), whereas bulk density recorded a negative significant correlation (r = −.942**) with grain yield. The results suggest that integrated use of FYM/lime with chemical fertilizers is a sustainable practice in terms of crop yield and soil health, whereas continuous application of urea alone is detrimental to the soil health. 相似文献
67.
Biology and Fertility of Soils - Sorption is an important process for retention of organic carbon (C) in soils. The effect of Na+ and Ca2+ on sorption of organic C has been studied in salt-affected... 相似文献
68.
69.
70.
Dhana Raj Boina Ebenezer O Onagbola Masoud Salyani Lukasz L Stelinski 《Pest management science》2009,65(8):870-877
BACKGROUND: Asian citrus psyllid (ACP), Diaphorina citri Kuwayama, transmits the causal bacteria of the devastating citrus disease huanglongbing (HLB). Because of the variation in spatial and temporal uptake and systemic distribution of imidacloprid applied to citrus trees and its degradation over time in citrus trees, ACP adults and nymphs are exposed to concentrations that may not cause immediate mortality but rather sublethal effects. The objective of this laboratory study was to determine the effects of sublethal concentrations of imidacloprid on ACP life stages. RESULTS: Feeding by ACP adults and nymphs on plants treated daily with a sublethal concentration (0.1 µg mL?1) of imidacloprid significantly decreased adult longevity (8 days), fecundity (33%) and fertility (6%), as well as nymph survival (12%) and developmental rate compared with untreated controls. The magnitude of these negative effects was directly related to exposure duration and concentration. Furthermore, ACP adults that fed on citrus leaves treated systemically with lethal and sublethal concentrations of imidacloprid excreted significantly less honeydew (7–94%) compared with controls in a concentration‐dependent manner suggesting antifeedant activity of imidacloprid. CONCLUSIONS: Sublethal concentrations of imidacloprid negatively affect development, reproduction, survival and longevity of ACP, which likely contributes to population reductions over time. Also, reduced feeding by ACP adults on plants treated with sublethal concentrations of imidacloprid may potentially decrease the capacity of ACP to successfully acquire and transmit the HLB causal pathogen. Copyright © 2009 Society of Chemical Industry 相似文献