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排序方式: 共有159条查询结果,搜索用时 15 毫秒
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113.
A study of the pineal gland of adult male blossomheaded parakeets was conducted with the aid of light microscopic examination to determine the influence of stress on pineal cells. It was demonstrated that stress decreased the growth and activity of the pinel cells when induced as hyperosmolality (water deprivation, salt ingestion). This influence on the pineal gland was not inhibited by previous treatment of a sympatholytic agent, 6-hydroxydopamine. 相似文献
114.
Tapan K. Mandal Animesh K. Chakraborty Anjan Bhattacharyya 《Pest management science》1995,45(3):215-219
Disposition kinetics of cypermethrin and fenvalerate were investigated in lactating black Bengal goats following single dose intravenous administration at 57 and 45 mg kg?1 respectively. The maximum and minimum blood concentrations of cypermethrin were 18.49 (±3.17) and 0.06 (±0.002) μg ml?1, while the corresponding values for fenvalerate were 14.58 (±2.37) and 0.04 (±0.005) μg ml?1 respectively. Both cypermethrin and fenvalerate remained present in blood for 36 h. The mean t1/2β) and Vdarea values were 5.56 (±0.28) h and 10.38 (±2.20) litre kg?1 for cypermethrin and 5.66 (±0.35) h and 11.31 (±2.20) litre kg?1 respectively for fenvalerate. Both cypermethrin and fenvalerate persisted in goat milk for 36 h. The t1/2β) and AUC values of fenvalerate were 7.37 (±1.84) h and 122.38 (±11.65) μg h ml?1 whilst the corresponding values for cypermethrin were 6.66 (±1.54) h and 99.48 (±7.81) μg h ml?1 in milk respectively. 相似文献
115.
John A. Herbert Avishek Chakraborty Luke W. Naylor William S. Beatty David G. Krementz 《Landscape Ecology》2018,33(8):1319-1334
Context
Management of wintering waterfowl in North America requires adaptability because constant landscape and environmental change challenges existing management strategies regarding waterfowl habitat use at large spatial scales. Migratory waterfowl including mallards (Anas platyrhynchos) use the lower Mississippi Alluvial Valley (MAV) for wintering habitat, making this an important area of emphasis for improving wetland conservation strategies, while enhancing the understanding of landscape-use patterns.Objectives
We used aerial survey data collected in the Arkansas portion of the MAV (ARMAV) to explain the abundance and distribution of mallards in relation to variable landscape conditions.Methods
We used two-stage, hierarchical spatio-temporal models with a random spatial effect to identify covariates related to changes in mallard abundance and distribution within and among years.Results
We found distinct spatio-temporal patterns existed for mallard distributions across the ARMAV and these distributions are dependent on the surrounding landscape structure and changing environmental conditions. Models performing best indicated seasonal surface water extent, rice field, wetland and fallow (uncultivated) fields positively influenced mallard presence. Rice fields, surface water and weather were found to influence mallard abundance. Additionally, the results suggest weather and changing surface water affects mallard presence and abundance throughout the winter.Conclusions
Using novel datasets to identify which environmental factors drive changes in regional wildlife distribution and abundance can improve management by providing managers additional information to manage land over landscapes spanning private and public lands. We suggest our analytical approach may be informative in other areas and for other wildlife species.116.
Sarkar M Chakraborty P Sharma BC Deka BC Duttaborah BK Mohanty TK Prakash BS 《Research in veterinary science》2008,85(2):233-237
Plasma progesterone profiles were used to assess superovulatory responses in cyclic yaks (n=10) in terms of the number of ovulations and the number of embryos recovered. The animals were synchronized into oestrus following Ovsynch treatment. All the animals received a total of 200 mg Folltropin divided into morning and evening and spread over 4 days, beginning on day 10 of the oestrus cycle (day of expected oestrus=day 0). Plasma samples for progesterone estimation were collected daily starting from the day of expected synchronized oestrus to the day of flushing. All the animals were palpated per rectum on the day of flushing in order to record the number of corpora lutea. Of an estimated 27 ovulations from the nine yaks, only 16 embryos were recovered. Plasma progesterone profiles from individual yaks suggested that a poor superovulatory response in terms of embryo recovery in some animals was caused by the lysis of corpora lutea before flushing which was carried out 7 days after superovulatory oestrus. It was suggested that flushing 5 days post superovulatory oestrus could improve the superovulatory response in this species. 相似文献
117.
Segenet Kelemu Daniel Z. Skinner Jorge L. Badel Claudia X. Moreno María X. Rodríguez Celso D. Fernandes María J. Charchar Sukumar Chakraborty 《European journal of plant pathology / European Foundation for Plant Pathology》1999,105(3):261-272
The degree of genetic diversity of 127 Colletotrichum gloeosporioides isolates from Stylosanthes guianensis genotypes in South America was measured at the molecular level by random amplified polymorphic DNA (RAPD) with nine arbitrary primers of 10 bases, and by restriction fragment length polymorphism (RFLP) with a non-LTR (long terminal repeats) retrotransposon DNA sequence. The RAPD products revealed scorable polymorphism among the isolates, and a total of 80 band positions were scored. Sixty-three of the 127 isolates were clustered into 13 distinct lineages usually correlating with geographic origin. Where isolates from various regions were clustered together, most had identical host genotype origin. The pathogen population sampled from Carimagua, Colombia, a long-time Stylosanthes breeding and selection site, with a savanna ecosystem, was highly diverse. A set of 12 S. guianensis genotype differentials was used to characterize pathogenic variability of 104 isolates and their virulence patterns were grouped into 57 pathotypes. However, when they were tested on four Australian differentials, they grouped into 11 pathotypes. As shown in previous studies, no strict correlations existed between genetic diversity measured by RAPD or RFLP, and pathotype defined by pathogenicity pattern on the differentials. Southern blot analysis of the 127 isolates revealed 23 hybridizing fragments, resulting in 41 fingerprint patterns among the 127 isolates. Relationships between RFLP and RAPD variables were examined using Spearman's Rank Correlation Coefficient, which showed that the two measures of genotypic variation are in agreement. 相似文献
118.
D. C. Weindorf S. Chakraborty J. Herrero B. Li C. Castañeda A. Choudhury 《European Journal of Soil Science》2016,67(2):173-183
Arid soil is common worldwide and has unique properties that often limit agronomic productivity, specifically, salinity expressed as soluble salts and large amounts of calcium carbonate and gypsum. Currently, the most common methods for evaluating these properties in soil are laboratory‐based techniques such as titration, gasometry and electrical conductivity. In this research, we used two proximal sensors (portable X‐ray fluorescence (PXRF) and visible near‐infrared diffuse reflectance spectroscopy (Vis–NIR DRS)) to scan a diverse set (n = 116) of samples from arid soil in Spain. Then, samples were processed by standard laboratory procedures and the two datasets were compared with advanced statistical techniques. The latter included penalized spline regression (PSR), support vector regression (SVR) and random forest (RF) analysis, which were applied to Vis–NIR DRS data, PXRF data and PXRF and Vis–NIR DRS data, respectively. Independent validation (30% of the data) of the calibration equations showed that PSR + RF predicted gypsum with a ratio of performance to interquartile distance (RPIQ) of 5.90 and residual prediction deviation (RPD) of 4.60, electrical conductivity (1:5 soil : water) with RPIQ of 3.14 and RPD of 2.10, Ca content with RPIQ of 2.92 and RPD of 2.07 and calcium carbonate equivalent with RPIQ of 2.13 and RPD of 1.74. The combined PXRF and Vis–NIR DRS approach was superior to those that use data from a single proximal sensor, enabling the prediction of several properties from two simple, rapid, non‐destructive scans. 相似文献
119.
The study was conducted to investigate the effect of dietary protein on nitrogenous excretion in the form of ammonia in Indian major carp, Labeo rohita (Ham.), fingerlings (3.0 ± 0.25 g). Fish were fed to satiation in a metabolism chamber. Approximately isoenergetic diets containing 230, 280, 330 and 380 g kg−1 protein were used at 28°C. Ammonia-N excretory energy ( U ) as a percentage of ingested food energy ( C ) increased with an increase in dietary protein level: from 4.3% in fish fed 230 g kg−1 to 6.0% in fish fed 380 g kg−1 dietary protein. The relationship between excretory energy and dietary protein level is modelled. 相似文献
120.
Sudipta Tripathi Sabitri Kumari Ashis Chakraborty Arindam Gupta Kalyan Chakrabarti Bimal Kumar Bandyapadhyay 《Biology and Fertility of Soils》2006,42(3):273-277
Seasonal fluctuations in salinity are typical in coastal soils due to the intrusion of seawater in the groundwater. We studied
the effect of salinity on the microbial and biochemical parameters of the salt-affected soils of the coastal region of Bay
of Bengal, Sundarbans, India. The average pH values and average organic C (OC) contents of soils from nine different sites
cultivated with rice (Oryza sativa) ranged from 4.8 to 7.8 and from 5.2 to 14.1 g kg−1, respectively. The average electrical conductivity of the saturation extract (ECe) during the summer season was about five times higher than that during the monsoon season. Within the nine sites, three soils
(S3, S4, and S5) were the most saline. The average microbial biomass C (MBC), average basal soil respiration (BSR), and average fluorescein
diacetate hydrolyzing activity (FDHA) were lowest during the summer season, indicating a negative influence of soil salinity.
About 59%, 50%, and 20% variation in MBC/OC, FDHA/OC, and BSR/MBC (metabolic quotient, qCO2), respectively, which are indicators of environmental stress, could be explained by the variation in ECe. The decrease in MBC and microbial activities with a rise in salinity is probably one of the reasons for the poor crop growth
in salt-affected coastal soils. 相似文献