全文获取类型
收费全文 | 96篇 |
免费 | 6篇 |
专业分类
102篇 |
出版年
2020年 | 1篇 |
2018年 | 3篇 |
2017年 | 3篇 |
2016年 | 2篇 |
2015年 | 3篇 |
2014年 | 2篇 |
2013年 | 4篇 |
2012年 | 5篇 |
2011年 | 3篇 |
2010年 | 7篇 |
2009年 | 5篇 |
2008年 | 2篇 |
2007年 | 5篇 |
2006年 | 10篇 |
2005年 | 2篇 |
2004年 | 6篇 |
2003年 | 3篇 |
2002年 | 1篇 |
2001年 | 3篇 |
1995年 | 1篇 |
1990年 | 3篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1984年 | 1篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1977年 | 1篇 |
1975年 | 2篇 |
1974年 | 1篇 |
1973年 | 2篇 |
1966年 | 1篇 |
1964年 | 1篇 |
1957年 | 1篇 |
1912年 | 3篇 |
1911年 | 1篇 |
1909年 | 1篇 |
1903年 | 1篇 |
1902年 | 1篇 |
排序方式: 共有102条查询结果,搜索用时 15 毫秒
71.
From the whole plants of Aster himalaicus, a new eudesmane‐type sesquiterpene, 1‐oxoeudesm‐11(13)‐eno‐12,8α‐lactone, along with twelve known compounds, was isolated. The structures of all compounds have been elucidated on the basis of spectroscopic data, including IR, EI‐MS, HR‐ESI‐MS, and 1D‐ and 2D‐NMR data. 相似文献
72.
Developing approaches for linear mixed modeling in landscape genetics through landscape‐directed dispersal simulations 下载免费PDF全文
Jeffrey R. Row Steven T. Knick Sara J. Oyler‐McCance Stephen C. Lougheed Bradley C. Fedy 《Ecology and evolution》2017,7(11):3751-3761
Dispersal can impact population dynamics and geographic variation, and thus, genetic approaches that can establish which landscape factors influence population connectivity have ecological and evolutionary importance. Mixed models that account for the error structure of pairwise datasets are increasingly used to compare models relating genetic differentiation to pairwise measures of landscape resistance. A model selection framework based on information criteria metrics or explained variance may help disentangle the ecological and landscape factors influencing genetic structure, yet there are currently no consensus for the best protocols. Here, we develop landscape‐directed simulations and test a series of replicates that emulate independent empirical datasets of two species with different life history characteristics (greater sage‐grouse; eastern foxsnake). We determined that in our simulated scenarios, AIC and BIC were the best model selection indices and that marginal R2 values were biased toward more complex models. The model coefficients for landscape variables generally reflected the underlying dispersal model with confidence intervals that did not overlap with zero across the entire model set. When we controlled for geographic distance, variables not in the underlying dispersal models (i.e., nontrue) typically overlapped zero. Our study helps establish methods for using linear mixed models to identify the features underlying patterns of dispersal across a variety of landscapes. 相似文献
73.
Leaf development involves many complex genetic interactions,signals between adjacent cells or between more distant tissues and consequent changes in cell fate.This review describes three stages in leaf development where regulation by small RNAs have been used to modulate gene expression patterns. 相似文献
74.
Row BS Knutzen KM Skogsberg NJ 《Journal of strength and conditioning research / National Strength & Conditioning Association》2012,26(3):664-671
Explosive resistance training (ERT) improves older adults' strength and power, and methods to make this form of training more accessible and useful to older adults are needed. The purpose of this study was to evaluate whether the rating of perceived exertion (RPE) scale would predict a broad range of ERT intensities on the leg press with older adults. If successful, then a load-RPE relationship could be used to regulate the intensity of training loads for ERT with older adults, allowing the elimination of maximal strength testing. Twenty-one older adults (≥65 years) with resistance training experience took part in 2 testing sessions. Session 1: Subjects performed high-velocity repetitions on the leg press for up to 9 loads (from 60 to 140% body weight) presented in quasi-randomized order, and then reported their RPE for each load. Session 2: A 1 repetition maximum (1RM) strength test was conducted. Regression analysis revealed that the average RPE across subjects for each load strongly predicted the average %1RM across subjects (R2 = 99.5%; p < 0.001). This allows the establishment of a load-RPE relationship for use in selecting ERT loads for older adults on the leg press. For example, high-intensity loads (70-90% 1RM) that would elicit both strength and power gains when used with ERT aligned with an RPE of 14-16. Lighter loads that may be useful for training for power, but not strength (<70% 1RM), were identified with RPE scores of 13 and lower. The load-RPE relationship may simplify the regulation of intensity of ERT with older adults on the leg press, where the exercising older adult could be guided to select loads according to their RPE. 相似文献
75.
Claudia Ciotir Heather Kirk Jeffrey R. Row Joanna R. Freeland 《Biological invasions》2013,15(6):1377-1390
The full effects of biological invasions may be underestimated in many areas because of cryptogenic species, which are those that can be identified as neither native nor introduced. In North America, the cattails Typha latifolia, T. angustifolia, and their hybrid T. × glauca are increasingly aggressive invaders of wetlands. There is a widespread belief that T. latifolia is native to North America and T. angustifolia was introduced from Europe, although there has so far been little empirical support for the latter claim. We used microsatellite data and chloroplast DNA sequences to compare T. latifolia and T. angustifolia genotypes from eastern North America and Europe. In both species, our data revealed a high level of genetic similarity between North American and European populations that is indicative of relatively recent intercontinental dispersal. More specifically, the most likely scenario suggested by Approximate Bayesian Computation was an introduction of T. angustifolia from Europe to North America. We discuss the potential importance of our findings in the context of hybridization, novel genomes, and increasingly invasive behaviour in North American Typha spp. 相似文献
76.
Mass spectrometric identification of a novel phosphorylation site in subunit NDUFA10 of bovine mitochondrial complex I 总被引:5,自引:0,他引:5
Schilling B Aggeler R Schulenberg B Murray J Row RH Capaldi RA Gibson BW 《FEBS letters》2005,579(11):2485-2490
Mitochondrial Complex I (NADH:ubiquinone oxidoreductase) consists of at least 46 subunits. Phosphorylation of the 42-kDa subunit NDUFA10 was recently reported using a novel phosphoprotein stain [Schulenberg et al. (2003) Analysis of steady-state protein phosphorylation in mitochondria using a novel fluorescent phosphosensor dye. J. Biol. Chem. 278, 27251]. Two smaller Complex I phosphoproteins, ESSS and MWFE, and their sites of modification, have since been determined [Chen et al. (2004) The phosphorylation of subunits of complex I from bovine heart mitochondria. J. Biol. Chem. 279, 26036]. Here we identify the site of phosphorylation in NDUFA10 from bovine heart mitochondria by tandem mass spectrometry. A single phosphopeptide spanning residues 47-60 was identified and confirmed by synthesis to be (47)LITVDGNICSGKpSK(60), establishing serine-59 as the site of phosphorylation. 相似文献
77.
L.Ramachandra Row K.Sambi Reddy N.Subrahmanya Sarma Teruo Matsuura Ruka Nakashima 《Phytochemistry》1980,19(6):1175-1181
The structures of physalins I, G and K are established respectively as 5,6-dihydro-5α-methoxy-6β-hydroxy, 4,5-dehydro-5,6-dihydro-4β-hydroxy and 5,6-dihydro-4α,5α-epoxy-6α-hydroxy derivatives of physalin B. The chemistry of physalin D, and the synthesis of physalins D and I from physalin F and physalin K from physalin G are described. 相似文献
78.
Simultaneous extraction and separation of liquiritin, glycyrrhizic acid, and glabridin from licorice were developed by liquidliquid
extraction with liquid chromatography separation. By utilizing different extraction solvents, procedures, and times, the optimum
extraction conditions were established. The extracts of licorice were separated and determined using a C18 column with a mobile phase consisting of acetonitrile-water (containing 1.0% acetic acid) with a gradient elution of 0∼10
min from 20:80 to 60:40 (v/v). Preparative columns with different packing sizes were investigated to isolate the three compounds
from the extracts of licorice. The 12 μm chromatographic column showed better separation for the three compounds from licorice.
0.29 mg/g for liquiritin, 1.43 mg/g for glycyrrhizic acid, and 0.07 mg/g for glabridin were obtained and the recoveries were
80.8, 89.7, and 72.5%, respectively. 相似文献
79.
Wentao Bi Minglei TianJun Zhou Kyung Ho Row 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》2010,878(24):2243-2248
Astaxanthin, as an outstanding antioxidant reagent, was successfully extracted from shrimp waste by the ionic liquids based ultrasonic-assisted extraction. Seven kinds of imidazolium ionic liquids with different cations and anions were investigated in this work and one task-specific ionic liquid in ethanol with 0.50 mol L−1 was selected as the solvent. At the optimized ultrasonic extraction conditions, the extraction amount of astaxanthin increased 98% (92.7 μg g−1) compared to the conventional method (46.7 μg g−1). Furthermore, the extracted solution was isolated through the solid-phase extraction with a molecularly imprinted polymer sorbent. After loading the samples on molecularly imprinted polymer cartridge, the different washing and elution solvents, such as water, methanol, n-hexane, acetone and dichloromethane, were evaluated, and finally, astaxanthin was separated from the shrimp waste extract. 相似文献
80.
Landscape characteristics influencing the genetic structure of greater sage‐grouse within the stronghold of their range: a holistic modeling approach 下载免费PDF全文
Jeffrey R. Row Sara J. Oyler‐McCance Jennifer A. Fike Michael S. O'Donnell Kevin E. Doherty Cameron L. Aldridge Zachary H. Bowen Bradley C. Fedy 《Ecology and evolution》2015,5(10):1955-1969
Given the significance of animal dispersal to population dynamics and geographic variability, understanding how dispersal is impacted by landscape patterns has major ecological and conservation importance. Speaking to the importance of dispersal, the use of linear mixed models to compare genetic differentiation with pairwise resistance derived from landscape resistance surfaces has presented new opportunities to disentangle the menagerie of factors behind effective dispersal across a given landscape. Here, we combine these approaches with novel resistance surface parameterization to determine how the distribution of high‐ and low‐quality seasonal habitat and individual landscape components shape patterns of gene flow for the greater sage‐grouse (Centrocercus urophasianus) across Wyoming. We found that pairwise resistance derived from the distribution of low‐quality nesting and winter, but not summer, seasonal habitat had the strongest correlation with genetic differentiation. Although the patterns were not as strong as with habitat distribution, multivariate models with sagebrush cover and landscape ruggedness or forest cover and ruggedness similarly had a much stronger fit with genetic differentiation than an undifferentiated landscape. In most cases, landscape resistance surfaces transformed with 17.33‐km‐diameter moving windows were preferred, suggesting small‐scale differences in habitat were unimportant at this large spatial extent. Despite the emergence of these overall patterns, there were differences in the selection of top models depending on the model selection criteria, suggesting research into the most appropriate criteria for landscape genetics is required. Overall, our results highlight the importance of differences in seasonal habitat preferences to patterns of gene flow and suggest the combination of habitat suitability modeling and linear mixed models with our resistance parameterization is a powerful approach to discerning the effects of landscape on gene flow. 相似文献