全文获取类型
收费全文 | 157篇 |
免费 | 2篇 |
专业分类
林业 | 11篇 |
农学 | 6篇 |
基础科学 | 4篇 |
55篇 | |
综合类 | 5篇 |
农作物 | 7篇 |
水产渔业 | 9篇 |
畜牧兽医 | 44篇 |
园艺 | 8篇 |
植物保护 | 10篇 |
出版年
2023年 | 1篇 |
2022年 | 2篇 |
2020年 | 1篇 |
2019年 | 6篇 |
2018年 | 4篇 |
2016年 | 4篇 |
2015年 | 4篇 |
2014年 | 7篇 |
2013年 | 26篇 |
2012年 | 13篇 |
2011年 | 15篇 |
2010年 | 13篇 |
2009年 | 8篇 |
2008年 | 7篇 |
2007年 | 6篇 |
2006年 | 11篇 |
2005年 | 2篇 |
2004年 | 4篇 |
2003年 | 7篇 |
2002年 | 3篇 |
2001年 | 3篇 |
2000年 | 2篇 |
1999年 | 1篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1984年 | 1篇 |
1976年 | 1篇 |
排序方式: 共有159条查询结果,搜索用时 0 毫秒
121.
One-day-old SPF chicks were inoculated with the Cux-l strain of chicken infectious anemia virus (CIAV), and the clinical development of disease and its macroscopic and microscopic alterations in the thymus and bone marrow, were observed. Tissue sections of thymus and bone marrow were stained using the streptavidin-biotin peroxidase method and examined under light microscope for evaluation of antigenic intensities in tissues. Those findings were then compared with blood parameters and ELISA results obtained through collected sera during sacrifice procedures. We sought to determine: the localization of viral antigens in thymus and bone marrow tissues after inoculation, the correlation between antigen intensities and hematologic, serologic and histopathologic findings, definitive diagnostic criteria using histopathologic and immunoperoxidase methods, and the reliability of these methods in the diagnosis of CIAV infection. For this purpose, 83, one-day-old SPF chicks were used. The birds were divided into experimental (n = 52) and control (n = 26) groups. A virus dose of TCID50 of 100,000/ml was administered intramuscularly to every bird in the experimental group. Based on the results of this study, we have suggested that clinical examination, along with macroscopic and microscopic evaluation of the thymus and bone marrow, maybe undertaken starting from day 7 post-inoculation (PI). ELISA, might be of value, as it might give consistent results starting from day 14 PI. However, the most reliable results were obtained through examination of thymus and bone marrow sections from infected birds stained by immunoperoxidase technique, as early as day 4 PI. 相似文献
122.
Potential decrease of grass tetany risk in rangelands combining N and K fertilization with MgO treatments 总被引:1,自引:0,他引:1
The most practical and effective method to increase dry matter production in rangelands is by adequate fertilization. N and K fertilizers have commonly been used worldwide to increase yield in rangelands. Fertilizers have a significant effect on mineral concentration in the forage. Risk of tetany, causing yield decrease and death in cattle, increases by feeding forage with a ratio of K/(Ca + Mg) ≥ 2.2. The fertilizers containing N and K are the most important factors increasing K/(Ca + Mg) ratio in forages. The present study has aimed to determine whether the tetany risks caused by K and N fertilization may be compensated by Mg fertilization. For this purpose, N (0 and 120 kg ha−1), K (0 and 100 kg ha−1) and Mg (0 and 30 kg ha−1) were applied as combinations of each other. Each plot was separated into three sub-plots sampled on 25 April, 15 May and 5 June to determine Ca, Mg, K concentrations and K/(Ca + Mg) ratio.In this 2-year study, dry matter production in the control plot was 2064 kg ha−1 and nitrogen application increased the dry matter production of the plots by about 100%. Dry weight ratios of grasses increased while legume dry weight ratios decreased drastically in response to N fertilization. An increase was observed in K/(Ca + Mg) ratio with N fertilization due to the fact that legumes have higher concentrations of Ca and Mg than grasses. K fertilization resulted in an approximately 30% increase of K concentration in dry matter. K/(Ca + Mg) ratio in plots where N and K were applied separately was lower than 2.2. However, K/(Ca + Mg) ratio in plots to which N and K were applied in combination was over 2.2, resulting in tetany risk. It is interesting to determine that Mg fertilization did not change Mg concentration in pasture. It was noted that tetany risk did not decrease with the advance of harvest dates. The results indicated that tetany risk caused by N and K fertilizations could not be compensated by Mg treatment. Therefore, it can be concluded that fertilization programmes avoiding legume decrease in rangelands may be useful to prevent the tetany risk. 相似文献
123.
Ulf Geisen Marion Zenthoefer Matthias Peipp Jannik Kerber Johannes Plenge Antonella Managò Markus Fuhrmann Roland Geyer Steffen Hennig Dieter Adam Levent Piker Gerald Rimbach Holger Kalthoff 《Marine drugs》2015,13(7):4470-4491
Pancreatic cancer is one of the most aggressive cancer entities, with an extremely poor 5-year survival rate. Therefore, novel therapeutic agents with specific modes of action are urgently needed. Marine organisms represent a promising source to identify new pharmacologically active substances. Secondary metabolites derived from marine algae are of particular interest. The present work describes cellular and molecular mechanisms induced by an HPLC-fractionated, hydrophilic extract derived from the Baltic brown seaweed Fucus vesiculosus (Fv1). Treatment with Fv1 resulted in a strong inhibition of viability in various pancreatic cancer cell lines. This extract inhibited the cell cycle of proliferating cells due to the up-regulation of cell cycle inhibitors, shown on the mRNA (microarray data) and protein level. As a result, cells were dying in a caspase-independent manner. Experiments with non-dividing cells showed that proliferation is a prerequisite for the effectiveness of Fv1. Importantly, Fv1 showed low cytotoxic activity against non-malignant resting T cells and terminally differentiated cells like erythrocytes. Interestingly, accelerated killing effects were observed in combination with inhibitors of autophagy. Our in vitro data suggest that Fv1 may represent a promising new agent that deserves further development towards clinical application. 相似文献
124.
125.
Nihat Şındak Levent Kandemir Muğdat Yertürk Halil Selçuk Biricik 《Veterinary ophthalmology》2010,13(4):219-221
Objective To determine physiologic levels of tear production in Arabian (AH) and throughbred horses (TH) by using phenol red thread test (PRT). Animals studied The study was performed on 16 AH and 14 TH, ranging from 2.5 to 24 years of age, housed in a stable situated in the Sanliurfa of Turkey. Procedures For the measurement of PRT, the strip was placed under the lower eyelid approximately one‐third the distance from the temporal to nasal canthus and left for 15 s. The length of the wet area was measured in mm and compared among breed, sex, and age groups and between eyes of both sides. Results The mean length of the wet area was in AH and TH were 30.22 ± 0.99 mm ranging from 16 to 41 and 31.00 ± 1.4 mm ranging from 14 to 47, respectively. There were no significant differences in tear production among breed, sex, or age groups. The values measured for left eyes were significantly higher than those for right eyes (P < 0.05). Conclusions Phenol red thread test measurement is easily used, with no pain, and a comfortable method. PRT can be used in equine ophthalmology on a routine basis to the measurement of tear production. These normal PRT values help diagnosis keratoconjunctivitis sicca in horses. 相似文献
126.
Aydin Adiloglu 《Archives of Agronomy and Soil Science》2013,59(3):275-281
This research was carried out in order to find out the effect of zinc application on the methods which can be used to determine available iron content of paddy soils. For this purpose, an experiment was carried out in greenhouse conditions by growing maize. The effect of increasing rates of zinc application on biological indexes of maize plants was determined. Eight chemical extraction methods for available iron content of soils were used and these methods are: 0.005 M DTPA+0.01 M CaCl2+0.1 M TEA; 0.005 N HCl+0.025 N H2SO4; 1 N NH4Oac; 0.01 N Na2EDTA+1 N NH4Oac; 2 N MgCl2; 0.01 M Na2EDTA +1 M (NH4)2CO3; 0.01 N Na2EDTA and 0.005 M DTPA+NH4HCO3. The relationships between biological indexes and chemical extraction methods were determined at the end of the experiment. The highest correlation coefficient was determined with the method 0.005 M DTPA+0.01 M CaCl2+0.1 M TEA. The iron content of maize plants decreased with zinc application and dry matter content increased with zinc application. 相似文献
127.
Aydin Adiloglu 《Archives of Agronomy and Soil Science》2013,59(3):283-287
This research was carried out in order to determine the effect of zinc (Zn) application on the available iron (Fe) contents of calcareous soils in Thrace Region. For this purpose, an experiment was carried out in greenhouse conditions by maize growing. The effect of increasing rates of Zn application on the biological indices of maize plant was determined. Fe concentration of maize plant decreased with Zn application and dry matter yield and Fe uptake of maize plant increased with Zn application. These decreases and increases were determined to be statistically significant (P<0.01). 相似文献
128.
Rising temperatures are a major threat to global wheat production, particularly when accompanied by other abiotic stressors such as mineral nutrient deficiencies. This study aimed to quantify the effects of supra‐optimal temperature on growth, photosynthetic performance, and antioxidative responses in bread wheat cultivars grown under varied zinc (Zn) supply. Two bread wheat cultivars (Triticum aestivum L., cvs. Lasani‐2008 and Faisalabad‐2008) with varied responsiveness to Zn supply and drought tolerance were cultured in nutrient solution with low (0.1 µM) or adequate (1.0 µM) Zn under optimal (25/20°C day/night) or supra‐optimal (36/28°C day/night) temperature regimes. Supra‐optimal temperature severely reduced root but not shoot biomass, whereas low Zn reduced shoot as well as root biomass. Shoot‐to‐root biomass ratio was reduced under low Zn but increased under supra‐optimal temperature. Supra‐optimal temperature inhibited root elongation and volume particularly in plants supplied with low Zn. In both cultivars, Zn efficiency index was reduced by supra‐optimal temperature, whereas heat tolerance index was reduced by low Zn supply. Supra‐optimal temperature decreased photosynthesis, quantum yield, and chlorophyll density in low‐Zn but not in adequate‐Zn plants. In comparison, low Zn decreased specific activities of superoxide dismutase (SOD) and ascorbate peroxidase (APX) and increased glutathione reductase (GR), where supra‐optimal temperature increased SOD, decreased GR and did not change APX activity in leaves and roots. Moreover, supra‐optimal temperature severely reduced shoot Zn concentration and Zn uptake per plant specifically under adequate Zn supply. Overall, supra‐optimal temperature exacerbated adverse effects of low Zn supply, resulting in severe reductions in growth traits viz. shoot and root biomass, root length and volume, and consequently impeded Zn uptake, enhanced oxidative stress and impaired photosynthetic performance. Adequate Zn nutrition is crucial to prevent yield loss in wheat cultivated under supra‐optimal temperatures. 相似文献
129.
130.
Diurnal variation in thermal environment experienced by salmonids in the North Pacific as indicated by data storage tags 总被引:2,自引:0,他引:2
Robert V. Walker Katherine W. Myers Nancy D. Davis Kerim Y. Aydin Kevin D. Friedland H. Richard Carlson George W. Boehlert Shigehiko Urawa Yasuhiro Ueno & Gen Anma 《Fisheries Oceanography》2000,9(2):171-186
Eight temperature-recording data storage tags were recovered from three salmonids in Alaska (pink and coho salmon and steelhead trout) and five chum salmon in Japan after 21–117 days, containing the first long-term records of ambient temperature from Pacific salmonids migrating at sea. Temperature data imply diel patterns of descents to deeper, cooler water and ascents to the surface. Fish were found at higher average temperatures at night, with narrower temperature ranges and fewer descents than during the day. Fish tagged in the Gulf of Alaska were at higher temperatures on average (10–12°C) than chum salmon tagged in the Bering Sea (8–10°C). Chum salmon were also found at a wider range of temperatures (−1–22°C vs 5–15°C). This is probably related both to the different oceanographic regions through which the fish migrated, as well as species differences in thermal range and vertical movements. Proportions of time that individual fish spent at different temperatures seemed to vary among oceanographic regions. Steelhead trout may descend to moderate depths (50 m) and not be limited to the top few metres, as had been believed. Japanese chum salmon may seek deep, cold waters as they encounter warm surface temperatures on their homeward migrations. Temperature data from all fish showed an initial period (4–21 days) of day and night temperatures near those of sea surface temperatures, suggesting a period of recuperation from tagging trauma. A period of tagging recuperation suggests that vertical movement data from short-term ultrasonic telemetry studies may not represent normal behaviour of fish. The considerable diurnal and shorter-term variation in ambient temperatures suggests that offshore ocean distribution may be linked more to prey distribution and foraging than to sea surface temperatures. 相似文献