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排序方式: 共有379条查询结果,搜索用时 46 毫秒
1.
Abir Dey Brahma Swaroop Dwivedi Ranjan Bhattacharyya Siba Prasad Datta Mahesh Chand Meena Raj K. Jat Raj Kumar Gupta Mangi Lal Jat Vinod Kumar Singh Debarup Das Ravi G. Singh 《Soil Use and Management》2020,36(3):429-438
Increasing soil carbon (C) in arable soils is an important strategy to achieve sustainable yields and mitigate climate change. We investigated changes in soil organic and inorganic carbon (SOC and SIC) under conservation agriculture (CA) in a calcareous soil of the eastern Indo-Gangetic Plains of India. The treatments were as follows: conventional-till rice and wheat (CT-CT), CT rice and zero-till wheat (CT-ZT), ZT direct seeded rice (DSR) and CT wheat (ZT-CT), ZTDSR and ZT wheat without crop residue retention (ZT-ZT), ZT-ZT with residue (ZT-ZT+R), and DSR and wheat both on permanent beds with residue (PB-PB+R). The ZT-ZT+R had the highest total SOC in both 0–15 and 15–30 cm soil layers (20% and 40% higher (p < .05) than CT-CT, respectively), whereas total SIC decreased by 11% and 15% in the respective layers under ZT-ZT+R compared with CT-CT. Non-labile SOC was the largest pool, followed by very labile, labile and less labile SOC. The benefits of ZT and residue retention were greatest for very labile SOC, which showed a significant (p < .05) increase (~50%) under ZT-ZT+R compared with CT-CT. The ZT-ZT+R sequestered ~2 Mg ha−1 total SOC in the 0–15 cm soil layer in 6 years, where CT registered significant losses. Thus, the adoption of CA should be recommended in calcareous soils, for C sequestration, and also as a reclamation technique. 相似文献
2.
Black-backed jackals (Canis mesomelas) are an abundant mesopredator on farmlands (croplands and rangelands) across South Africa. Given their adaptability in a changing anthropogenic landscape, knowledge of spatial movements can provide important ecological information on the species. We captured, collared and monitored five black-backed jackals in the Midlands of KwaZulu-Natal to determine their home range and habitat use in farmlands. The 95% fixed kernel (95% FK) home range sizes were large, showing a marked seasonal variation in movement. One adult male dispersed 150?km over two seasons (winter and spring) and thereafter settled into a home range that it maintained. Transient home ranges of males and juveniles were larger than resident home ranges. The mean resident home ranges (95% FK) across seasons for adult males, adult female and juvenile males were 11.4 ± 4.3 km2, 5.6 ± 0.36?km2 and 2.15 ± 0.45?km2, respectively. The mean transient home ranges (95% FK) of all the seasons for adult and juvenile males were 1 181.93 ± 575.81 km2 and 104.27 ± 35.64?km2, respectively. Adult jackal preferred croplands in spring, summer and autumn but avoided croplands in winter. Variable habitat use and large home ranges in our study confirmed the species’ ability to adapt to agricultural areas. 相似文献
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R. Ramesh Kumar L. Prasanna Anjaneya ReddyJ. Vinay Kumar K. KomaraiahS. Purnanand K.P. Sastry 《Industrial Crops and Products》2012,35(1):199-202
Ashwagandha (Withania somnifera) is an important medicinal plant and its dried roots are used in traditional systems of medicine. The market price of roots is determined by physical (textural) quality. Brittle roots with high starch and low fiber are considered to be superior because of ease in grinding. Genetic diversity studies based on root textural parameters have not been done so far. So the present study was designed to assess genetic diversity for morphometric traits and root textural quality parameters among two morphologically distinct groups: Poshita and Nagore. The PCA separated the morphometric and root texture variables distinctly into two different principal components: PC-1 and PC-2 respectively, indicating that both are negatively associated. All the morphotypes in Poshita group showed high positive loadings in PC-1 indicating that component genotypes are high root yielding. Nagore morphotypes were low yielding but the root texture was good. Clustering of morphotypes grouped Poshita and Nagore separately with high inter-cluster distances indicating that both groups are highly divergent from each other, suggesting that there is sufficient scope for varietal improvement through hybridization. 相似文献
7.
Field experiments were conducted during 1989 and 1990 to study the effect of various soil management practices on water conservation during the two prime planting periods in the lower Himalayan region. Treatments studied were: zero tillage with weed control (ZT+W), zero tillage (ZT), fine tilth (FT), coarse tilth (CT), zero tillage with surface-applied lantana (Lantana camara L.) mulch at 10 t ha−1 (ZT+M), fine tilth with surface-applied lantana mulch at 10 t ha−1 (FT+M), fine tilth with surface-applied farmyard manure mulch at 10 t ha−1 (FT+FYM) and fine tilth with FYM incorporated at 10 t ha−1 (FYM). The soils were Typic Hapludalfs with pH 5.8, organic carbon 6.6 g kg−1 and cation exchange capacity 12 cmol (P+) (100 g)−1. The lantana mulch application to fine tilth (FT+M) or zero tillage (ZT+M) maintained higher seed-zone water content and profile water storage as compared with all the other treatments. Highest water depletion was observed under ZT+W treatment. Seed germination is likely to occur only under FT+M and ZT+M during the two prime planting periods, if field capacity water content is considered to be limiting for seed germination. However, for the other treatments rainfall would invariably be required to increase the surface water content, to allow germination and early seedling establishment. 相似文献
8.
As an alternative to ground-cover data collection by conventional and expensive sampling techniques, we compared measurements
obtained from very large scale aerial (VLSA) imagery for calibrating moderate resolution Landsat data. Using a grid-based
sampling scheme, 162 VLSA images were acquired at 100 m above ground level. The percent vegetation cover in each photo was
derived using SamplePoint (a manual inventory method) and VegMeasure (a reflectance based, automated method). Approximately
two-thirds of the VLSA images were used for calibrating Landsat data while the remainder was used for validation. Regression
models with Landsat bands accounted for 55% of the VegMeasure-based measurements of vegetation, whereas models that included
both Landsat bands and elevation data accounted for 67%. The relationship between the Landsat bands and the percent vegetation
cover measured by SamplePoint was lower (R
2 = 20%), highlighting the differences between the inventory and reflectance based protocols. Results from the model validation
indicated that the model’s predictive power was lower when the vegetation cover was either <20% or >55%. Additional work is
needed in these ecosystems to improve the calibration techniques for sites with low and high vegetation cover; however, these
results demonstrate the VLSA imagery could be used for calibrating Landsat data and deriving rangeland vegetation cover. By
adopting such methodologies the US Federal land management agencies can increase the efficiency of the monitoring programs
in Wyoming and in other western states of the US.
Mention of trade names is for information only and does not imply endorsement by USDA over comparable products or services. 相似文献
9.
Rao GS Ramesh S Ahmad AH Tripathi HC Sharma LD Malik JK 《Veterinary research communications》2001,25(3):197-204
The pharmacokinetics of enrofloxacin and its active metabolite ciprofloxacin were investigated in goats after a single intramuscular administration of enrofloxacin at 2.5 mg/kg body weight. The plasma concentrations of enrofloxacin and ciprofloxacin were determined simultaneously by a HPLC method. The peak concentrations (C
max) of enrofloxacin (1.13 g/ml) and ciprofloxacin (0.24 g/ml) were observed at 0.8 and 1.2 h, respectively. The elimination half-life (t
1/2), volume of distribution (V
d(area)), total body clearance (ClB) and mean residence time (MRT) of enrofloxacin were 0.74 h, 1.42 L/kg, 1329 ml/h per kg and 1.54 h, respectively. The t
1/2, area under the plasma concentration–time curve (AUC) and the MRT of ciprofloxacin were 1.38 h, 0.74 g h/ml and 2.73 h, respectively. The metabolic conversion of enrofloxacin to ciprofloxacin was appreciable (36%) and the sum of the plasma concentrations of enrofloxacin and ciprofloxacin was maintained at or above 0.1 g/ml for up to 4 h. Enrofloxacin appears to be useful for the treatment of goat diseases associated with pathogens sensitive to this drug. 相似文献
10.
Weeds PL Chakraborty S Fernandes CD d'A Charchar MJ Ramesh CR Kexian Y Kelemu S 《Phytopathology》2003,93(2):176-185
ABSTRACT Using molecular markers, this work compares the genetic diversity in Colletotrichum gloeosporioides infecting species of the tropical forage legume Stylosanthes at the center of origin in Brazil and Colombia with that of Australia, China, and India, where Stylosanthes spp. have been introduced for commercial use. There was extensive diversity in the pathogen population from Brazil, Colombia, China, and India. The Australian pathogen population was least diverse probably due to its geographical isolation and effective quarantine. The extensive diversity in China and India means that threats from exotic pathogen races to Stylosanthes pastures can potentially come from countries outside the South American center of origin. In Brazil and India, both with native Stylosanthes populations, a high level of genetic differentiation in the pathogen population was associated with sites where native or naturalized host population was widely distributed. There was limited genetic diversity at germplasm evaluation sites, with a large proportion of isolates having identical haplotypes. This contrasts recent pathogenicity results for 78 of the Brazilian isolates that show hot spots of complex races are more common around research stations where host germplasm are tested, but few are found at sites containing wild host populations. For a pathogen in which the same races arise convergently from different genetic backgrounds, this study highlights the importance of using both virulence and selectively neutral markers to understand pathogen population structure. 相似文献