首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   162篇
  免费   9篇
林业   16篇
农学   1篇
基础科学   4篇
  30篇
综合类   4篇
农作物   11篇
水产渔业   24篇
畜牧兽医   57篇
园艺   7篇
植物保护   17篇
  2023年   3篇
  2022年   2篇
  2021年   3篇
  2020年   6篇
  2019年   3篇
  2018年   7篇
  2017年   8篇
  2016年   9篇
  2015年   6篇
  2014年   7篇
  2013年   16篇
  2012年   15篇
  2011年   13篇
  2010年   12篇
  2009年   12篇
  2008年   8篇
  2007年   9篇
  2006年   11篇
  2005年   5篇
  2004年   2篇
  2003年   2篇
  2002年   5篇
  2001年   2篇
  1998年   1篇
  1995年   1篇
  1969年   2篇
  1968年   1篇
排序方式: 共有171条查询结果,搜索用时 15 毫秒
81.
The purpose of this study was to characterize the Irano-Caucasian apricot germplasm that was collected in Anatolia, Turkey. Fifteen (pomological, phenological, and yield) parameters were studied in this germplasm, consisting of 128 apricot cultivars and types. A wide variation was found in harvest season, fruit yield, total solids soluble (TSS), total acidity, fruit, pit, and kernel mass. Most of the cultivars and types had a relatively small fruit size; only seven had a fruit mass ≥50 g. In general, fruits had yellow skin ground color and flesh color as well as mostly sweet kernels and high TSS. While there was a high correlation between fruit, pit and kernel mass and also between TSS and total acidity, a low or no significant correlation was determined between other pomological or phenological characteristics. The Levent apricot type possessed a substantially late ripening with a total period of 190–200 days for fruit development, a characteristic that makes this apricot type highly suitable for breeding studies.  相似文献   
82.
Genetic Resources and Crop Evolution - Pistachio (Pistacia vera L.) is the only cultivated species in Pistacia genus and it is one of the most important species of hard-shelled fruits. Pistachio...  相似文献   
83.
Citrus mealybug Planococcus citri (Risso) (Hemiptera: Pseudococcidae) is one of the main pests on citrus trees. Biological control of the pest is based on the release of hymenopterous parasitoids and coccinellid predators at present. The effectiveness of entomopathogen fungus Isaria farinosa (Holmsk.) Fries ([Sordariomycetes: Hypocreales] (Syn: Paecilomyces farinosus), as an alternative biological control agent on citrus mealybug, was investigated using four different inoculum densities and different relative humidities (RH). The entomopathogen caused 89.39% mortality in ovisacs, 84.07% mortality in second larval stage, 84.53% mortality in adult females, and 78.71% mortality in first larval stage at 95% RH and at 1 × 108 conidia ml−1 inoculum concentration. Percent mortalities were between 50 and 60 in ovisac, first and second larval stage at 95% RH and at 1 × 107 conidia ml−1. Percent mortality was decreased parallel to the decrease in humidity level and inoculum densities; however, the fungus caused significant infection in 70% and 80% RH. These results demonstrated that the effectiveness of the entomopathogen is promising for biocontrol of citrus mealybug.  相似文献   
84.
Collecting information at the interface between living cells and artificial substrates is exceedingly difficult. The extracellular matrix (ECM) mediates all cell-substrate interactions, and its ordered, fibrillar constituents are organized with nanometer precision. The proceedings at this interface are highly dynamic and delicate. In order to understand factors governing biocompatibility or its counterpart antifouling, it is necessary to probe this interface without disrupting labels or fixation and with sufficient temporal resolution. Here the authors combine nonlinear optical spectroscopy (sum-frequency-generation) and microscopy (second-harmonic-generation), fluorescence microscopy, and quartz crystal microgravimetry with dissipation monitoring in a strategy to elucidate molecular ordering processes in the ECM of living cells. Artificially (fibronectin and collagen I) and naturally ordered ECM fibrils (zebrafish, Danio rerio) were subjected to nonlinear optical analysis and were found to be clearly distinguishable from the background signals of diffusive proteins in the ECM. The initial steps of fibril deposition and ordering were observed in vitro as early as 1 h after cell seeding. The ability to follow the first steps of cell-substrate interactions in spite of the low amount of material present at this interface is expected to prove useful for the assessment of biomedical and environmental interfaces.  相似文献   
85.
Here we investigated the in vitro and in vivo effects of the pesticides, deltamethrin, diazinon, propoxur and cypermethrin, on the activity of rainbow trout (rt) gill carbonic anhydrase (CA). The enzyme was purified from rainbow trout gills using Sepharose 4B-aniline-sulfanilamide affinity chromatography method. The overall purification was approx. 214-fold. SDS-polyacrylamide gel electrophoresis showed a single band corresponding to a molecular weight of approx. 29 kDa. The four pesticides dose-dependently inhibited in vitro CA activity. IC50 values for deltamethrin, diazinon, propoxur and cypermethrin were 0.137, 0.267, 0.420 and 0.460 μM, respectively. In vitro results showed that pesticides inhibit rtCA activity with rank order of deltamethrin > diazinon > propoxur > cypermethrin. Besides, in vivo studies of deltamethrin were performed on CA activity of rainbow trout gill. rtCA was significantly inhibited at three concentrations (0.25, 1.0 and 2.5 μg/L) at 24 and 48 h.  相似文献   
86.
This work reports on the newly synthesized 9-tosyl-9H-carbazole (TsCz) monomer. Capacitive properties of the electrochemically grown homopolymer, poly(TsCz) film on carbon fibre microelectrode (CFME), are characterised by cyclic voltammetry (CV), Fourier transform infrared reflectance-attenuated total reflection spectroscopy (FTIR-ATR), scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS). Different monomer concentrations (1, 3 and 10 mM) were used for electrodeposition in 0.1 M sodium perchlorate (NaClO4)/acetonitrile (ACN) solution. The capacitive behaviour of modified CFMEs was defined via Nyquist, Bode-magnitude and Bode-phase plots. An equivalent electrical circuit R(CR)(QR)(CR) for different concentrations of poly(TsCz)/CFME was proposed and experimental data were simulated to obtain the numerical values of the circuit components. The Nyquist plot for poly(TsCz) shows the highest specific capacitance (50.0 mF cm−2) at frequency of 0.01 Hz in the initial monomer concentration of 10 mM.  相似文献   
87.
In tomato, the predominant flavonoid is quercetin-3-rutinoside (rutin). In this study, we aim to investigate the phenylalanine ammonia-lyase (PAL) and the quercetin-3-O-glucosyl transferase (3-GT) reactions in the formation of rutin during tomato fruit ripening. Tomatoes of the Moneymaker variety at different development stages (green, breaker, turning, pink, red, and deep red) were divided into flesh and peel fractions. In each sample, both the content of rutin and the enzymatic activities for PAL and 3-GT were recorded. The highest activities of PAL were recorded in the peel of turning fruit (3,000 μkat/mg fresh weight). In fruit flesh, maximal activity was observed in red fruit (917.3 μkat/mg). For both tissues, PAL activity strongly decreased at the final (deep red) fruit stage. The activity of 3-GT in peel peaked in the turning fruit stage (50.7 pkat/mg), while in flesh maximal activity (33.4 pkat/mg) was observed in green fruit, which rapidly declined at the turning stage. Higher levels of rutin were detected in the tomato peel compared to the flesh part with the highest level being found at the green stage. The relation of PAL and 3-GT activities to rutin content is also evaluated.  相似文献   
88.
The present study aimed to investigate the effect of thiamine on growth, hematological, egg thiamine content and oocyte nucleus migration indices in sterlet sturgeon (Acipenser ruthenus). A total of 45 female fish (698.6 ± 8.9 g) were distributed in nine fiberglass tanks with three treatments (each in three replicates). Experimental fish were fed once a day with practical diet supplemented with 1 g kg?1 amprolium hydrochloride (as the antithiamine) for 5 months before spawning. Thiamine hydrochloride was injected to fish with one of three doses at 0, 5 and 50 mg kg?1 body weight (BW) at three different stages. At the end of each month, fish were weighed and growth parameters such as weight gain, specific growth rate, feed efficiency and final weight were determined. At the end of the 5-month period, hematological parameters and egg thiamine content were measured. The results showed no significant differences in terms of growth performance. Hemoglobin, number of red blood cells and white blood cells were not significantly different among the treatments, but hematocrit was significantly higher in fish injected with 5 mg kg?1 BW thiamine. The mean corpuscular volume and mean corpuscular hemoglobin were not significantly different, but lower value of mean corpuscular hemoglobin concentration was observed in fish injected with 5 mg thiamine. Percentage of lymphocytes, neutrophils, eosinophils and monocytes were not significantly different among treatments. The results of the germinal vesicle migration index at different stages showed no significant differences in different groups. Results showed that free thiamine, thiamine pyrophosphate and total thiamine in eggs significantly increased at 50 mg kg?1 injection dose compared with the control, but no significant different was found in thiamine monophosphate. The results revealed that thiamine injection to sterlet broodstocks has positive accumulation in egg thiamine content and some hematological parameters but have no effect on growth and ovarian maturation. We conclude that thiamine can affect some physiological features of broodstock, which needs to be specified in further studies.  相似文献   
89.
The most parts of the Earth experience precipitation variability as a part of their normal climates over both short- and long-time periods. These variations of precipitation will have unpredictable and perhaps unexpectedly extreme consequences(such as drought and flood) with respect to frequency and intensity for many regions of the Earth. Because of high precipitation fluctuations, the Mediterranean region is also the areas of the world sensitive to precipitation changes which often involve frequent drought conditions in Turkey. In this study, drought conditions at annual, seasonal and monthly time scales over the period of 1975–2010 were examined for Antakya-Kahramanmara? Graben which is located in the eastern part of the Mediterranean region of Turkey. Application of appropriate measures to analyze and monitor droughts is recognized as a major challenge to scientists involved in atmospheric studies. Standardized Precipitation Index(SPI) and cumulative deviation curve techniques were used to determine drought conditions. Results indicated that the study area presented a cyclic pattern of variations with alternating drier and wetter years. From analyses of annual, seasonal and monthly drought series it can be seen that precipitation characteristic of the area is changing. By the results, apparent wet and dry periods can be distinguished. This study also indicated that precipitation totals of winter, spring and summer seasons were slightly decreased during the study period. Drought frequency was increased especially for the northern part of the area in the last ten years. Drought periods were divided into 1982–1985, 1999–2002 and 2004–2008, respectively. According to our analyses, the time scale of 1999–2002 was the driest period in the most of the graben area. The study area, which covers agriculturally important fertile alluvial plains, will experience increasing pressure on its water resources because of its growing population and industry, ever-larger demands for intensive agricultural activities, and frequent drought events.  相似文献   
90.
The effects of Isaria farinosa (Holm.) and Beauveria bassiana (Balsamo) on adult stages of sunn pests Eurygaster integriceps Puton and Eurygaster austriaca (Schrk.) were investigated at 27±1°C, 95% r.h. and 16L:8D in the laboratory. Two concentrations, 1×106 and 1×108 conidia ml-1, were used. Mortality of inoculated and non-inoculated adults was counted at 6, 9 and 12 days after treatment. Beauveria bassiana caused higher mortality of both species than I. farinosa. Neither caused significantly high mortality at 1×106 conidia ml-1. Both were more pathogenic at 1×108 conidia ml-1 and caused more than 85% mortality 12 days post treatment. Both were more pathogenic to E. austriaca.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号