全文获取类型
收费全文 | 410篇 |
免费 | 11篇 |
专业分类
林业 | 28篇 |
农学 | 38篇 |
基础科学 | 5篇 |
104篇 | |
综合类 | 32篇 |
农作物 | 22篇 |
水产渔业 | 14篇 |
畜牧兽医 | 117篇 |
园艺 | 14篇 |
植物保护 | 47篇 |
出版年
2022年 | 6篇 |
2021年 | 5篇 |
2020年 | 11篇 |
2019年 | 3篇 |
2018年 | 18篇 |
2017年 | 11篇 |
2016年 | 19篇 |
2015年 | 3篇 |
2014年 | 8篇 |
2013年 | 37篇 |
2012年 | 15篇 |
2011年 | 20篇 |
2010年 | 13篇 |
2009年 | 12篇 |
2008年 | 15篇 |
2007年 | 25篇 |
2006年 | 23篇 |
2005年 | 7篇 |
2004年 | 12篇 |
2003年 | 4篇 |
2002年 | 5篇 |
2001年 | 10篇 |
2000年 | 5篇 |
1999年 | 9篇 |
1997年 | 3篇 |
1996年 | 4篇 |
1995年 | 5篇 |
1994年 | 5篇 |
1993年 | 4篇 |
1992年 | 7篇 |
1991年 | 3篇 |
1990年 | 9篇 |
1989年 | 10篇 |
1988年 | 7篇 |
1987年 | 6篇 |
1986年 | 6篇 |
1985年 | 6篇 |
1983年 | 5篇 |
1982年 | 2篇 |
1981年 | 6篇 |
1979年 | 4篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1973年 | 3篇 |
1971年 | 4篇 |
1970年 | 3篇 |
1969年 | 3篇 |
1968年 | 2篇 |
1967年 | 3篇 |
1952年 | 1篇 |
排序方式: 共有421条查询结果,搜索用时 31 毫秒
51.
Effect of long‐term fertilization and manuring on potassium release properties in a Typic Ustochrept
A long‐term fertilizer experiment, over 27 years, studied the effect of mineral fertilizers and organic manures on potassium (K) balances and K release properties in maize‐wheat‐cowpea (fodder) cropping system on a Typic Ustochrept. The treatments consisted of control, 100% nitrogen (100% N), 100% nitrogen and phosphorus (100% NP), 50% nitrogen, phosphorus, and potassium (50% NPK), 100% nitrogen, phosphorus, and potassium (100% NPK), 150% nitrogen, phosphorus, and potassium (150% NPK), and 100% NPK+farmyard manure (100% NPK+FYM). Nutrients N, P, and K in 100% NPK treatment were applied at N: 120 kg ha—1, P: 26 kg ha—1, and K: 33 kg ha—1 each to maize and wheat crops and N: 20 kg ha—1, P: 17 kg ha—1, and K: 17 kg ha—1 to cowpea (fodder). In all the fertilizer and manure treatments removal of K in the crop exceeded K additions and the total soil K balance was negative. The neutral 1 N ammonium acetate‐extractable K in the surface soil (0—15 cm) ranged from 0.19 to 0.39 cmol kg—1 in various treatments after 27 crop cycles. The highest and lowest values were obtained in 100% NPK+FYM and 100% NP treatments, respectively. Non‐exchangeable K was also depleted more in the treatments without K fertilization (control, 100% N, and 100% NP). Parabolic diffusion equation could describe the reaction rates in CaCl2 solutions. Release rate constants (b) of non‐exchangeable K for different depth of soil profile showed the variations among the treatments indicating that long‐term cropping with different rates of fertilizers and manures influenced the rate of K release from non‐exchangeable fraction of soil. The b values were lowest in 100% NP and highest in 100% NPK+FYM treatment in the surface soil. In the sub‐surface soil layers (15—30 and 30—45 cm) also the higher release rates were obtained in the treatments supplied with K than without K fertilization indicating that the sub‐soils were also stressed for K in these treatments. 相似文献
52.
53.
C. M. Mehta D. Yu R. Srivastava A. Sinkkonen J. M. Kurola V. Gupta 《Compost science & utilization》2016,24(2):105-116
The present study aimed to investigate microbial communities in seven Indian composts and their potential for biocontrol of Fusarium oxysporum f. sp. lycopersici. In addition, identification of bioactive substances in disease suppressive composts was also attempted. Composts were chosen based on disease suppressiveness and subjected to molecular microbial analyses. Total genomic DNA from the composts was extracted and amplified with polymerase chain reaction using primers targeting the 18S rRNA and 16S rRNA genes of fungi and bacteria, respectively. Denaturing gradient gel electrophoresis (DGGE) fingerprinting and DNA sequencing were used to identify the fungal and bacterial targets. Phylogenetic analysis of the fungal 18S rRNA ITS gene sequences showed that phylum Ascomycota was dominant in all composts, while in the bacterial 16S rRNA gene sequences, the phylum Proteobacteria was dominant. Some fungi in disease suppressive composts grouped phylogenetically close to F. oxysporum. Bacterial sequences with close similarity (>95% identity) with Actinobacterium showed a strong presence only in disease suppressive composts. Disease suppressive composts formed a separate group in the cluster analysis of 18S rRNA ITS and 16S rRNA gene sequences. Gas chromatography-time of flight-mass spectrometry was performed with compost extracts to determine if bioactive substances were present in disease suppressive composts. The analysis of compost organic matter showed a negative association of disease suppressiveness with phloroglucinol, sitosterol, and monoenoic fatty acid, while cholesterol and certain organic acids were positively associated with suppressiveness. 相似文献
54.
Efforts were made to develop soil fertility variogram-based site-specific nutrient management (SSNM) practices in Nagpur mandarin (Citrus reticulata Blanco) grown on smectite clay soil (Typic Ustorthent and Typic Haplustert) of central India. Different SSNM treatments were more responsive on Ustorthent than Haplustert due to difference in type and magnitude of multiple nutrient deficiencies. Best SSNM treatment in terms of response on canopy growth, yield, fruit quality, and soil-plant nutrient buildup were observed to be T9 [nitrogen (N1200) + phosphorus (P600) + potassium (K600) + M1S1] and T6 (N600 + P400 + K300 + M1S1) on shallow soil and deep soil, respectively, within the same orchard. Fertilizer use needs to be tailored per these doses instead of recommended doses of fertilizers (RDF) (T16) as a basis. Effect of K was more pronounced at N600 + P400 (T5–T8) than at N1200 + P600 (T9–T12), irrespective of soil types. 相似文献
55.
Anjana Srivastava Kailash Singh Rawat Santosh Chandra Bhatt Deepa Rawat Prakash Chandra Srivastava 《Communications in Soil Science and Plant Analysis》2016,47(17):1961-1966
The aim of the study was to evaluate the degradation and persistence of 2-amino 4-chloro 6-methyl pyrimidine (AM), nitrification inhibitor at 1 and 2 µg g?1 application rates in soil. The extraction of AM was done by QuEChER’s (Quick, Easy. Cheap. Rugged and Safe) method and the quantitative analysis by high-performance liquid chromatography (HPLC). AM decreased with time at both the levels of application with the decline being faster in the beginning up to 7 d. Dissipation of AM occurred in a single phase with the persistence data fitting well to the first-order kinetics. Half-lives of AM were determined to be 14.33 and 16.7 d at 1 and 2 µg g–1 levels application rates. Since AM remains effective for an adequate period of time, it can be used for increasing efficiency of nitrogenous fertilizers in rice–wheat cropping systems as well as a safeguard for controlling environmental pollution in subtropical soils. 相似文献
56.
This study was carried out to compare the diversity in seed production and the soil seed bank in a dryland and an irrigated agroecosystem in the dry tropics. Both agroecosystems showed a comparable number of species, but only 25% and 38% similarity during the winter and rainy cropping seasons, respectively. In the irrigated agroecosystem, the amount of seed production diversity was almost double in the winter season, compared to the rainy season. The weed seedbank diversity was low but was sensitive to cropping practices and seasons in both agroecosystems. A considerably smaller soil seedbank size in the irrigated agroecosystem (cf. dryland) was related to lowered weed seed production. The dryland agroecosystem showed a greater accumulation of the seeds of broad‐leaved weeds, whereas the irrigated agroecosystem accumulated more seeds of the grasses or sedges. About three‐fourths of the seeds during the winter season were accounted for by Anagallis arvensis and Chenopodium album in the dryland agroecosystem and by C. album and Melilotus indica in the irrigated agroecosystem. However, during the rainy season, Ammannia baccifera, Echinochloa colona and Cyperus rotundus dominated in both agroecosystems. The changes in the weed seed bank and its diversity are mainly attributed to differences in water management, which tends to reduce species diversity, especially at a lower depth, but leads to the dominance of some potentially noxious weeds (e.g. Phalaris minor and M. indica). Approximately double the soil seedbank size and a greater diversity at a lower depth might indicate an adaptive mechanism in the storage of weed seeds in the dryland agroecosystem. 相似文献
57.
Srivastava A Harish R Shivanandappa T 《Journal of agricultural and food chemistry》2006,54(3):790-795
Roots of Decalepis hamiltonii are consumed as pickles and as a health drink in southern India for their health benefits. The antioxidant properties of the root extracts have been shown previously; this paper reports the isolation of antioxidant compounds from the aqueous extract of the roots of D. hamiltonii. Five novel antioxidant compounds were isolated and characterized by NMR and MS. The compounds exhibited free radical scavenging activity in vitro and inhibited low-density lipoprotein oxidation. This study demonstrates that the root extract of D. hamiltonii is a cocktail of several antioxidant compounds with health implications. 相似文献
58.
Archana Suyal Prakash Chandra Srivastava 《Communications in Soil Science and Plant Analysis》2018,49(14):1750-1760
A study was undertaken to investigate the remedial effect of some soil amendments (farmyard manure (FYM), press mud compost (PMC), cereal straw (CS) at 5 t ha?1 and fresh cow dung slurry (FCD) @ 0.5 t ha?1) on dissipation kinetics of imidacloprid and sulfosulfuron under laboratory conditions. Incorporation of CS or FCD was found to be most effective in degrading both the pesticides at faster rates. Dissipation of both the pesticides could be well accounted by two component (1 + 1) first order kinetics. The computed values of parameters revealed that use of organic amendments increased the dissipated fraction of imidacloprid and sulfosulfuron. Incorporation of CS or FCD in soil maintained relatively higher dissipation rate constants for both faster and slower dissipation processes of pesticides in comparison to control. Hence, eco-friendly practices of CS or FCD incorporation as soil amendment in soil can play a vital role in preventing soil and water pollution. 相似文献
59.
Sachin Kumar Vaid Arun Kumar Anita Sharma P. C. Srivastava A. K Shukla 《Communications in Soil Science and Plant Analysis》2017,48(7):756-768
The quest for plant growth promotory bacteria that can help in sustainable agriculture has increased in the recent years owing to increasing cost of fertilizers. In the present study, the potential of three isolated bacteria having plant growth promotory effects in mobilizing the indigenous soil iron (Fe) in two different varieties of wheat was evaluated. Three bacterial isolates belonging to the genera Burkholderia and Acinetobacter were evaluated singly and in combinations for Fe uptake of wheat in a net house study. Results showed that bacterial isolates when used in combination performed better in comparison to their individual use. These isolates significantly increased the mean Fe concentration in grains and straw by 34.0% and 52.4% over the uninoculated controls and also increased the total Fe uptake per pot in comparison to uninoculated controls. The bacterial inoculation also showed a positive impact on the bioavailability of diethylenetriaminepentaacetic acid (DTPA) extractable Fe in soil. 相似文献
60.
Sachin Srivastava A. K. Chopra Piyusha Sharma Vinod Kumar 《Communications in Soil Science and Plant Analysis》2017,48(5):511-523
A field experiment was conducted to study the biohydrological properties of soil and yield of Vigna unguiculata L. Walp irrigated with five concentrations of sugar mill wastewater (SMW) during the Kharif and Zaid seasons. Among various concentrations of SMW, irrigation with 100% SMW significantly (P < 0.001) increased zinc (Zn), copper (Cu), cadmium (C), nickel (Ni), chromium (Cr), and iron (Fe) of the soil, while decreased total bacteria, fungi, actinomycetes, yeast, and rhizobia of the soil in both the cultivated seasons. However, the values of these metals were below the recommended permissible limit except Cd. Enrichment factor (Ef) of various heavy metals for soil was in the order Ni > Cr > Cd > Zn > Cu after irrigation with SMW. The crop yield of V. unguiculata was found to be inversely proportional to concentrations of SMW, with the best results being obtained at 50% SMW concentrations after 90 days of irrigation in both the cultivated seasons. 相似文献