全文获取类型
收费全文 | 827篇 |
免费 | 40篇 |
专业分类
林业 | 53篇 |
农学 | 128篇 |
基础科学 | 23篇 |
154篇 | |
综合类 | 57篇 |
农作物 | 63篇 |
水产渔业 | 36篇 |
畜牧兽医 | 266篇 |
园艺 | 13篇 |
植物保护 | 74篇 |
出版年
2022年 | 9篇 |
2021年 | 14篇 |
2020年 | 22篇 |
2019年 | 15篇 |
2018年 | 18篇 |
2017年 | 31篇 |
2016年 | 25篇 |
2015年 | 19篇 |
2014年 | 23篇 |
2013年 | 53篇 |
2012年 | 45篇 |
2011年 | 38篇 |
2010年 | 30篇 |
2009年 | 31篇 |
2008年 | 32篇 |
2007年 | 27篇 |
2006年 | 22篇 |
2005年 | 25篇 |
2004年 | 12篇 |
2003年 | 16篇 |
2002年 | 23篇 |
2001年 | 21篇 |
2000年 | 13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 | 12篇 |
1985年 | 7篇 |
1984年 | 9篇 |
1983年 | 12篇 |
1982年 | 9篇 |
1981年 | 13篇 |
1980年 | 6篇 |
1979年 | 15篇 |
1978年 | 9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867条查询结果,搜索用时 0 毫秒
41.
The methanol extract of the dried fruit powder of Terminalia pallida was evaluated for antimicrobial activity. The methanol extract showed a broad spectrum of antibacterial activity. 相似文献
42.
OBJECTIVE: Malnutrition is responsible globally for 60% of deaths among children under 5 years and is often attributed to suboptimal feeding practices. In response, the World Health Organization recommends exclusive breast-feeding for the first 6 months of life. The objective of this study was to determine if an association exists between the early introduction of water and complementary foods (CFs) and the nutritional status of children in northern Senegal. DESIGN/SETTING/SUBJECTS: A cross-sectional study of 374 children in the Podor Health District between the ages of 6 and 23 months was conducted. Knowledge and behaviours of mothers regarding introduction of water and CFs were assessed via individual interviews. RESULTS: Water was introduced to about 85% of the children in the first 3 months of life and 62% were fed CFs before 6 months. Overall, 16% had clinically significant wasting (weight-for-length Z-score (WHZ) less than - 2) and 20% had stunting (height-for-age Z-score (HAZ) less than - 2). There was no significant association between wasting or stunting and introduction of water before 3 months (WHZ: odds ratio = 0.99, 95% confidence interval 0.46-2.14, P = 0.97; HAZ: 0.68, 0.34-1.36, P = 0.3) or introduction of CFs before 6 months (WHZ: 0.81, 0.46-1.42, P = 0.5; HAZ: 0.79, 0.46-1.35, P = 0.4). A significant association was found between wasting and male sex, age, living in Guede community, drinking river/pond water and large family size, while stunting was associated with age and drinking tap water. CONCLUSION: The results of the present study suggest that early introduction of water and CFs is frequent and is not associated with increased risk for malnutrition among children from this region of northern Senegal, but the possibility of reverse causality cannot be excluded. 相似文献
43.
44.
T. N. Jacob J. P. Pandey K. Raghuveer G. Sreenivasulu A. D. Gupta M. Yoshikuni A. Jagota B. Senthilkumaran 《Fish physiology and biochemistry》2005,31(2-3):271-274
Effect of experimentally induced thyroxine overdose on the testis and seminal vesicles was studied in the air-breathing catfish,
Clarias gariepinus during the preparatory and the pre-spawning phase. The present study revealed a marked reduction in testosterone level in
serum, testis and seminal vesicles (SV). Histological examination showed a considerable reduction in the number of spermatozoa/spermatids
in the seminiferous tubular lumen as well as depletion of fluid in the loculi of SV. SDS-PAGE analysis of SV fluid proteins
demonstrated a significant decrease in the level of a ~27 kDa protein in thyroxine treated fishes. Evidences are presented
here to indicate that thyroid hormone plays a role in regulating testis and SV function in catfish.
T.N. Jacob and J.P. Pandey contributed equally 相似文献
45.
To improve the breeding of chickpea varieties with resistance to Fusarium wilt, an attempt was made to analyse the biochemical basis of disease resistance by measuring levels of chitinase, β-1,3-glucanase, protease and proteinase inhibitor activities in dry and soaked seeds and in root and shoot tissues of wilt-resistant and wilt-susceptible cultivars. Marginal variation was observed in the levels of the candidate proteins in dry or soaked seeds. Chitinase activity was higher in roots than in shoots or cotyledons. No proteinase inhibitor activity was detected in root and shoot tissue of any of the cultivars. When the levels of these proteins were analysed in resistant (Vijay) and susceptible (JG-62) cultivars during development of wilt by growing plants in soil infested with F. oxysporum f.sp. ciceri , race 1, both cultivars showed induction of chitinase activity in the roots. However, the induced activity in JG-62 (3.82 U g−1 ) was equivalent to the constitutive level in Vijay (3.90 U g−1 ) and much lower than that induced in Vijay (5.18 U g−1 ). Induction of protease activity was observed only in root extracts of Vijay when challenged by the pathogen. The root extract of Vijay showed in vitro antifungal activity in a plate assay. Simultaneous induction of proteolytic and chitinolytic activities specifically in the resistant cultivar was correlated with antifungal properties of root extracts effective in conferring resistance. 相似文献
46.
Avijit Gupta 《Land Degradation \u0026amp; Development》2012,23(1):102-102
47.
S. Gupta R. Kaushal R. S. Spehia S. S. Pathania V. Sharma 《Journal of plant nutrition》2017,40(7):921-927
Inorganic fertilizers alone cannot sustain high levels of productivity. This study was conducted to determine whether higher productivity of capsicum could be achieved by conjoint application of chemical fertilizers and plant growth promoting rhizobacteria (PGPR). Four PGPR isolates (RS2, RS3, RS4, and RS7) from capsicum roots and rhizosphere were evaluated at Solan, Himachal Pradesh (India), during 2009–2012. Two best performers: RS2 and RS7 were tried singly or in consortium with different levels of chemical fertilizers under field conditions, Randomized Block Design, replicated thrice. The conjoint use of 100% recommended nitrogen, phosphorus, and potassium (NPK) doses through chemical fertilizers (RDF) plus PGPR significantly increased fruit yield, plant height, and biomass by 37%, 20%, and 30%, respectively, over sole application of 100% RDF (control). Further, response of capsicum to 80% RDF plus PGPR was statistically comparable with control. The results, therefore, indicate the potential of isolated PGPR strains to substitute about 20% NP fertilizers besides enhanced productivity of capsicum. 相似文献
48.
A series of 2-alkyl-7, 8-dihydro-3-hydroxynaphtho[1,2-c]chromen-6-ones was synthesised by the condensation of ethyl 3, 4-dihydro-1-oxonaphthalene-2-carboxylate with substituted phenols in the presence of POCl3. The compounds were characterised and tested for their toxicity towards the mycelial growth of seven phytopathogenic fungi in culture. Drechslera oryzae, Rhizoctonia solani and Colletotrichum falcatum exhibited maximum sensitivity to these compounds whereas Macro-phomina phaseolina, Fusarium solani, Alternaria alternata and Pythium aphanidermatum were less sensitive. 2-Ethyl-7, 8-dihydro-3-hydroxy-naphtho[1,2-c]chromen-6-ones possessed greatest toxicity with EC50 values ranging from 0.2 to 2.5 μg ml?1 against all fungi except A. alternata and P. aphanidermatum. 相似文献
49.
Molecular genetic mapping of quantitative trait loci associated with loaf volume in hexaploid wheat (Triticum aestivum) 总被引:1,自引:0,他引:1
M. Elangovan R. Rai B.B. Dholakia M.D. Lagu R. Tiwari R.K. Gupta V.S. Rao M.S. Rder V.S. Gupta 《Journal of Cereal Science》2008,47(3):587-598
Major efforts in wheat research are being made to improve the yield and quality of wheat. Loaf volume (Lv) is the main quality parameter deciding the bread making potential of wheat. To genetically dissect quantitative trait loci (QTLs) for Lv, a Recombinant Inbred Line (RIL) population (F8) was developed from a cross between two Indian wheat varieties “HI 977” and “HD 2329”. A total of 914 SSR and 100 ISSR primers were used for molecular analysis and the genetic map comprising 19 chromosomes was constructed with 202 SSR markers and 2 HMW glutenin subunit loci: Glu-B1 and Glu-D1. The phenotypic data were collected from six environments including three different agro-climatic zones for 2 consecutive years. Dissection of Lv through AMMI model revealed significant G×E variance for the trait. QTL analysis was performed using composite interval mapping. A total of 30 QTLs for Lv were detected and significant QTLs were identified on 6B and 6D chromosomes; 1B, 1D, 2A, 3A, 5B and 5D also contributed genetically to Lv. Association between 6B and 6D QTLs and variable expression of gliadins on group 6 chromosomes were discussed. QTLs detected in this study were compared with other QTL analysis in wheat. 相似文献
50.
Das A Katole S Kumar A Gupta SP Saini M Swarup D 《Journal of animal physiology and animal nutrition》2012,96(3):442-449
A feeding trial was conducted to determine the optimum level of crude protein (CP) in the diet of captive blackbuck (Antelope cervicapra) in which feed consumption and nutrient utilization are maximal. Fifteen blackbucks (BW 25-34 kg) were distributed into three groups of five each in an experiment of 75-days duration including a digestion trial of 5-day collection period. All the animals were offered 200 g of concentrates and fresh maize fodder ad libitum. The overall CP content of the three respective diets was 6.9%, 10.4% and 12.7%. Blood samples were collected on the last day of the experiment. Intake and digestibility of CP increased (p < 0.01) with the increased level of CP in the diet. Feed consumption and nutrient intake were not significantly different among the groups. However, digestibilities of most of the nutrients were higher in the 10.4% CP diet than in the 6.9% CP diet. The endogenous loss of nitrogen was similar among the groups. Based on the endogenous losses, minimum N requirement was calculated to be 776 mg/kg BW(0.75) /day, and to meet this requirement, diet must contain at least 8.27% CP. Serum urea nitrogen concentration increased (p < 0.01) with increased level of dietary CP. Serum level of glutamate oxaloacetate transaminase and glutamate pyruvate transaminase was higher (p < 0.05) in the group fed 6.9% CP diet. Animals in the group fed low protein diet also lost body mass during the experimental period. It was concluded that a diet containing 10.4% CP was optimum for maximizing nutrient utilization without any adverse effect on voluntary feed consumption and serum metabolite profile of blackbucks. 相似文献