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   147篇
  免费   6篇
林业   9篇
农学   7篇
基础科学   1篇
  44篇
综合类   6篇
农作物   37篇
水产渔业   12篇
畜牧兽医   22篇
园艺   1篇
植物保护   14篇
  2022年   7篇
  2021年   15篇
  2020年   12篇
  2019年   9篇
  2018年   15篇
  2017年   9篇
  2016年   12篇
  2015年   4篇
  2014年   9篇
  2013年   21篇
  2012年   6篇
  2011年   7篇
  2010年   4篇
  2009年   4篇
  2008年   9篇
  2007年   3篇
  2006年   1篇
  2005年   2篇
  2004年   1篇
  2002年   1篇
  1998年   1篇
  1988年   1篇
排序方式: 共有153条查询结果,搜索用时 15 毫秒
91.
Determination of chilling and heat requirements of pistachio (Pistacia vera L.) cultivars is important for satisfactory growth and development, particularly when large-scale commercial production is desired. This experiment was conducted to determine chilling requirement inducing vegetative and flower buds of Kalle-Ghuchi, Owhadi, Ahmad-Ahgaei, and Akbari pistachio. Shoots with enough vegetative and flower buds were taken from pistachio trees during autumn 2007 and 2008 when temperature reached to 15°C. Cuttings with flower buds were kept under (5 ± 1)°C for 0, 600, 650, 700, 750, 800, 850, 900, 950, 1 000, 1 050, 1 100, 1 150, 1 200, 1 250, and 1 300 h, respectively, and cuttings with vegetative buds were kept at 51°C until 1 500 h. The results indicated that pistachio cultivars requite chilling time between 750-1 400 h and heat requirements between 8 852-15 420 growing degree hours (GDH). Consequently, Kalle-Ghuchi had the lowest chilling (750-950 h), and heat (8 852-9 768 GDH) requirements, Ahmad-Aghaei and Owhadi had intermediate (1 000-1 250 h, 10 656- 13 320 GDH) and Akbari had the highest chilling (1 200-1 400 h) and heat (11 863-15 420 GDH) requirement.  相似文献   
92.
Journal of Plant Diseases and Protection - The parasitic weed Orobanche crenata is a serious constraint to legumes crops in Mediterranean area. In Morocco, heavy O. crenata infestation level was...  相似文献   
93.
Variation of high molecular weight glutenin subunits (HMW-GS) in 28 Iranian Aegilops tauschii (2n = 2x = 14, DD) accessions studied by sodium dodecyl sulphate electrophoresis method (SDS-PAGE). The results showed high variation of HMW-GS in the accessions. The range of frequency in 14 HMW-GS combinations was 3.57–25 % in the accessions. AMOVA showed the molecular variance between the geographic areas was lower than within the geographic areas. According to Nei’s genetic diversity, the highest diversity levels were in Semnan, Golestan and Azarbayjan, on the other hand the lowest levels of diversity were found in Khorasan, Gilan and Mazandaran accessions. Hence, the Caspian Sea South East accessions also Azerbayjan in Iran have more diversity. AMOVA did not show variance between strangulata and tauschii but there was more genetic diversity in ssp. tauschii subspecies in comparison of ssp. strangulata according to Nei’s gene diversity and Shannon information index. It showed Iranian Ae. tauschii have a good potential for bread making quality improvement in bread wheat.  相似文献   
94.
Journal of Plant Diseases and Protection - Pot experiments with winter wheat were conducted for two successive years to study the relationship between the cereal cyst nematode, Heterodera...  相似文献   
95.
The aim of this work was to determine metal accumulation by plants growing on three molybdenum-mine zones and their tolerance strategies. The plants from tailing, extracting and non-contaminated zones were sampled with their corresponding soils. The results show that molybdenum (Mo) and copper (Cu) were at toxic levels in soils and their levels varied in 44 collected species from 21 families. Ajuga chamaecistus and Cramb orientalis L. excluded Mo and Cu, respectively. Achilla tenuifollia as Mo-hyperaccumulator with total Mo (1979 mg kg?1) and then Erodium ciconium with 1308 mg kg?1 Mo and Conyza Canadensis with 618 mg kg?1 Cu were moderate metal accumulators. They stored considerable levels of metals in their leaves vacuoles and elevated the levels of phytochelatins, cysteine and glutathione and induced antioxidant enzymes. In conclusion, this study indicated that some collected plants excluded metals. In metal-accumulators, antioxidant enzymes, phytochelatins and sequestration of excess metals were involved in their tolerance mechanism.  相似文献   
96.
The aim of this study was to provide data to assess the additive effects of soil salinity on the toxicity of Cd to soil alkaline phosphatase (EC 3.1.3.1). Two soils (Langroud acid soil and Shervedan calcareous soil) were artificially salinized with NaCl. The natural and salinized soils were treated with CdSO4 solutions to give a Cd concentration in the range 3–5000 mg kg?1. Soil alkaline phosphatase activity was measured after 3 days of incubation. Salinity enhanced the extractable Cd concentration in both Langroud and Shervedan soils. The percentage of soil alkaline phosphatase activity inhibited by Cd was significantly increased from 27.8 to 45 in the Langroud acid soil as salinity increased from natural levels to 28 dS m?1. An increase in the inhibition percentage was not observed in the Shervedan soil. Lower values for the ecological dose causing 50% inhibition (ED50) under saline conditions in the Shervedan soil supported the hypothesis that Cd may be more toxic to soil alkaline phosphatase when the soil is more saline. We conclude that Cd toxicity to soil alkaline phosphatase is salinity dependent and that higher Cd concentrations under saline conditions are probably responsible for the enhanced Cd toxicity to soil alkaline phosphatase.  相似文献   
97.
African trypanosomes cause human sleeping sickness and livestock trypanosomiasis in sub-Saharan Africa. We present the sequence and analysis of the 11 megabase-sized chromosomes of Trypanosoma brucei. The 26-megabase genome contains 9068 predicted genes, including approximately 900 pseudogenes and approximately 1700 T. brucei-specific genes. Large subtelomeric arrays contain an archive of 806 variant surface glycoprotein (VSG) genes used by the parasite to evade the mammalian immune system. Most VSG genes are pseudogenes, which may be used to generate expressed mosaic genes by ectopic recombination. Comparisons of the cytoskeleton and endocytic trafficking systems with those of humans and other eukaryotic organisms reveal major differences. A comparison of metabolic pathways encoded by the genomes of T. brucei, T. cruzi, and Leishmania major reveals the least overall metabolic capability in T. brucei and the greatest in L. major. Horizontal transfer of genes of bacterial origin has contributed to some of the metabolic differences in these parasites, and a number of novel potential drug targets have been identified.  相似文献   
98.
Background:TNF-α and IL-6 are both pleiotropic cytokines playing major roles in cancer-associated cytokine networks. They have previously been investigated for their function in skin malignancies, mostly melanomas, and studies on NMSC patients are relatively rare. In this study, we aimed to assess the associations of serum levels of IL-6 and TNF-α with NMSCs and its clinicopathological features. Methods:This cases-control study was carried out to investigate the serum levels of TNF-α and IL-6 in 70 NMSC patients, in comparison with 30 healthy individuals, by means of flow cytometric bead-based immuneoassay. Results:Serum levels of both TNF-α and IL-6 were significantly higher in NMSC patients (6.470 vs. 4.355 pg/ml; p = 0.0468, respectively), compared to healthy individuals (3.205 vs. 0.000 pg/ml; p = 0.0126, respectively). In the subgroup analysis, SCC patients had higher serum levels of IL-6 compared to healthy individuals (3.445 vs. 0.000 pg/ml; p = 0.0432). No other significant differences were observed in the serum levels of these two cytokines among different clinicopathological subgroups of the patients. Conclusion:The increased levels of TNF-α and IL-6 in NMSC patients can be introduced as an epiphenomenon of a complex cancer-induced cytokine cascade. Key Words: Biomarkers, Cytokines, Interleukin-6, Tumor Necrosis Factor-alpha  相似文献   
99.
Changes of cervical ultrasonographic physical parameters and their association with outcome of cerclage have not been fully elucidated. This study aimed at evaluating association between ultrasonographic physical cervical shapes before and after McDonald cerclage with the length of pregnancy. Cervical length, width and funneling rate were assessed by transvaginal ultrasonography before and after the procedure. Mean pre-cerclage cervical length, width and funneling rate were 29.28 +/- 5.54, 19.92 +/- 10.30 mm and 12.90 +/- 18.87%, respectively. The mean post-cerclage cervical length, diameter and funneling rate were 31.68 +/- 4.21, 9.78 +/- 13.86 and 4.32 +/- 10.89%, respectively (p < 0.001 for all pre- and post-cerclage changes). The mean post-cerclage duration of pregnancy was 19.78 +/- 5.94 weeks. There were significant direct correlations between the pre-and post-cerclage cervical lengths with pregnancy duration (r = 0.24, p = 0.04 and r = 0.44, p < 0.001, respectively). There were significant indirect correlations between the pre- and post-cerclage funneling rate with pregnancy duration (r = -0.30, p = 0.01 and r = -0.20, p = 0.01, respectively). Similar correlations were not significant for the cervical widths. This study showed that the pre- and post-cerclage ultrasonographically determined cervical length and funneling are good predictors of pregnancy duration.  相似文献   
100.
BACKGROUND: Although pyrimethamine (Tindurin) appears to be effective in the prevention and treatment of some infectious diseases, very little information exists on its unpredictable properties. We design this study to evaluate its anti-tumoral effect on a model of cell line. METHODS: The cytotoxic influence of Pyrimethamine on prostate cell line was investigated using an in vitro colometric assay. The potential modulatory effects on metastasis, apoptosis, and immortality characteristics of cells were assessed with gelatin zymography, terminal deoxyribonucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) assay and telomeric repeat amplification protocol, respectively. RESULTS: Cytotoxicity analysis of pyrimethamine revealed a dose-dependent fashion. An apoptotic influence of pyrimethamine was also confirmed by data obtained from TUNEL assay. Dose-dependent inhibitory effect on matrix metalloproteinases (MMP) was seen in pyrimethamine. A potent inhibitory effect of pyrimethamine was also established by data achieved from TRAPeze telomerase detection kit. CONCLUSIONS: Collectively, as induction of apoptosis together with MMP and telomerase inhibition could be indicative of cancer treatment, pyrimethamine might be considered as a chemopreventative agent in cancer.  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