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141.
陆地棉萌发至三叶期不同生育阶段耐盐特性   总被引:12,自引:0,他引:12  
摘要:土壤盐渍化是一个世界性的资源问题和生态问题,盐分胁迫几乎会影响棉花所有重要的生命活动, 造成棉花的减产或其他不利影响。本试验通过对14个品棉花种(系)的萌发期耐盐性、芽期耐盐性以及两个耐盐性不同的品种(系)三叶期的耐盐性,对棉花不同时期的耐盐特性进行了研究,结果表明:棉花在不同生育阶段耐盐能力是不同的,棉花盐敏感时间是在萌发出苗期。随着生育期的延长,棉花的耐盐性是逐步提高的,进行耐盐性鉴定的最佳时期在是萌发出苗期。在三叶期,随着盐分浓度的提高,棉花苗受伤害程度逐渐增加,盐敏感性品种受伤害大于耐盐品种,在同样盐浓度胁迫条件下,耐盐性不同的品种各部分受到的伤害不同,耐盐品种(系)中棉所35受伤害程度由高到低依次为:真叶>上胚轴>子叶;盐敏感品种(系)Tamcot CAB-CS受伤害程度由高到低依次为:真叶> 子叶>上胚轴。  相似文献   
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Amino acid racemization is presented as an hypothesis for the cause of aging. Effects on important biomolecules resulting from changes in their three-dimensional conformations and resulting changes in activities and specificities are discussed. Aging is viewed as a natural process associated with attaining thermodynamic equilibrium.  相似文献   
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We report a compact, cost‐effective tuned amplifier for frequency‐selective amplification of the modulated signal in heterodyne detected nonlinear optical microscopy. Our method improved the signal to noise ratio by an order of magnitude compared to conventional lock‐in detection, as demonstrated through stimulated Raman scattering imaging of live cells and tissues at the speed of 2 μsec/pixel. Application of the tuned amplifier to transient absorption microscopy is also demonstrated. The increased signal to noise ratio allowed epi‐detected in vivo imaging of myelin and blood in rat spinal cord with high spatial resolution. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   
148.
Novel immunotherapeutic agents targeting tumor-site microenvironment are revolutionizing cancer therapy. Chimeric antigen receptor (CAR)-engineered T cells are widely studied for cancer immunotherapy. CD19-specific CAR-T cells, tisagenlecleucel, have been recently approved for clinical application. Ongoing clinical trials are testing CAR designs directed at novel targets involved in hematological and solid malignancies. In addition to trials of single-target CAR-T cells, simultaneous and sequential CAR-T cells are being studied for clinical applications. Multi-target CAR-engineered T cells are also entering clinical trials. T cell receptor-engineered CAR-T and universal CAR-T cells represent new frontiers in CAR-T cell development. In this study, we analyzed the characteristics of CAR constructs and registered clinical trials of CAR-T cells in China and provided a quick glimpse of the landscape of CAR-T studies in China.  相似文献   
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In an effort to exploit the natural antifungal pogostone, its simplified scaffold dehydroacetic acid (DHA) was used as a lead compound to semi-synthesize 56 DHA derivatives ( I1 – 48 , II , III , and IV1 – 6 ). Among them, compound IV4 exhibited the most potent antifungal activity with 11.0 μM EC50 against mycelial growth of Sclerotinia sclerotiorum (Lib.) de Bary whose sclerotia production was also completely suppressed at this concentration. Furthermore, IV4 could completely inhibit infection cushion formation of S. sclerotiorum on rape leaves and achieved a preventive efficacy of 90.2 % at 500 μM, which was on the same level as that of commercial boscalid at 30 μM (88.7 %). The results of physiological and ultrastructural studies indicated that IV4 might disrupt the cell membrane permeability or induce the imbalance of mitochondrial membrane potential homeostasis to exert the antifungal mode of action. Besides, the robust and predicative three-dimensional quantitative structure-activity relationship (3D-QSAR) models were developed and discussed herein.  相似文献   
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  1. Our project sought to determine ecological effects of adding low-head dams and levees to large rivers by examining potential changes to aquatic food webs over a 70-year period in the Lower Ohio River (LOR) and Upper Mississippi River (UMR).
  2. We employed museum collections of fish and compound specific stable isotope analysis of amino acids to evaluate long-term changes in primary food sources for multiple species of fish in each river.
  3. Fishes in both rivers depended more on autochthonous than allochthonous carbon sources throughout the 70-year period (based on measurements of isotopic signatures of algae, C3 plants, C4 plants, cyanobacteria, and fungi), but the relative use of different carbon sources differed between the UMR and LOR. Significant but opposite shifts in trophic positions (TP) between rivers over time (higher TP in the UMR; lower in the LOR) were correlated with major anthropogenic changes to habitat structure (e.g. slight decrease in abundance of side channels in the UMR; increase in pool water depth in the LOR) resulting from low-head dam construction. They may also have been influenced by likely increased primary productivity in the UMR from agricultural nitrogen inputs and by possible shifts in the importance of phytoplankton versus benthic algae in the LOR from changes in water depth. Shifts in trophic position and reliance on various food sources were not correlated with variation in discharge, gage height, or temperature.
  4. Although these two rivers have contrasting hydrogeomorphic complexity (UMR is an anastomosing river, while the LOR is a constricted channel river) and different discharge patterns (seasonal versus yearly operation in some cases), both differ substantially from rivers having hydrogeomorphic changes resulting from construction of high dams (>15 m). It is not surprising, therefore, that factors controlling trophic position and reliance on different carbon sources vary among different types of dams and river structures.
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