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211.
菠萝蜜中香气成分分析 总被引:8,自引:0,他引:8
纳智 《热带亚热带植物学报》2004,12(6):538-540
用溶剂法提取菠萝蜜中的香气成分,用GC-MS联用技术鉴定了82个化合物,占香气成分总量的94.66%,主要为脂肪酸类以及酯类、醇类、烷氧基烷烃类和酮类物质,主要成分为亚油酸(24.10%),棕榈酸(15.72%)和油酸(6.16%)。 相似文献
212.
Background
Genetic association studies are conducted to discover genetic loci that contribute to an inherited trait, identify the variants behind these associations and ascertain their functional role in determining the phenotype. To date, functional annotations of the genetic variants have rarely played more than an indirect role in assessing evidence for association. Here, we demonstrate how these data can be systematically integrated into an association study’s analysis plan.Results
We developed a Bayesian statistical model for the prior probability of phenotype–genotype association that incorporates data from past association studies and publicly available functional annotation data regarding the susceptibility variants under study. The model takes the form of a binary regression of association status on a set of annotation variables whose coefficients were estimated through an analysis of associated SNPs in the GWAS Catalog (GC). The functional predictors examined included measures that have been demonstrated to correlate with the association status of SNPs in the GC and some whose utility in this regard is speculative: summaries of the UCSC Human Genome Browser ENCODE super–track data, dbSNP function class, sequence conservation summaries, proximity to genomic variants in the Database of Genomic Variants and known regulatory elements in the Open Regulatory Annotation database, PolyPhen–2 probabilities and RegulomeDB categories. Because we expected that only a fraction of the annotations would contribute to predicting association, we employed a penalized likelihood method to reduce the impact of non–informative predictors and evaluated the model’s ability to predict GC SNPs not used to construct the model. We show that the functional data alone are predictive of a SNP’s presence in the GC. Further, using data from a genome–wide study of ovarian cancer, we demonstrate that their use as prior data when testing for association is practical at the genome–wide scale and improves power to detect associations.Conclusions
We show how diverse functional annotations can be efficiently combined to create ‘functional signatures’ that predict the a priori odds of a variant’s association to a trait and how these signatures can be integrated into a standard genome–wide–scale association analysis, resulting in improved power to detect truly associated variants.Electronic supplementary material
The online version of this article (doi:10.1186/1471-2164-15-398) contains supplementary material, which is available to authorized users. 相似文献213.
NA LUO FANGMING XIAO JAMES J. CAMBERATO YIWEI JIANG 《Plant, cell & environment》2013,36(11):2021-2033
Natural variation in salinity response, effects of population structure on growth and physiological traits and gene–trait association were examined in 56 global collections of diverse perennial ryegrass (Lolium perenne L.) accessions. Three population structure groups were identified with 66 simple sequence repeat markers, which on average accounted for 9 and 11% of phenotypic variation for the control and salinity treatment at 300 mm NaCl. Group 1 (10 accessions) had greater plant height, leaf dry weight and water content, chlorophyll index, K+ concentration and K+/Na+ than group 2 (39 accessions) and group 3 (7 accessions) under salinity stress, while group 3 had higher Na+ than groups 1 and 2. Eighty‐seven single nucleotide polymorphisms were detected from four partial candidate genes encoding aquaporin and Na+/H+ antiporter in both plasma and tonoplast membranes. Overall, rapid decay of linkage disequilibrium was observed within 500 bp. Significant associations were found between the putative LpTIP1 and Na+ for the control and between the putative LpNHX1 and K+/Na+ under the control and salinity treatments after controlling population structure. These results indicate that population structure influenced phenotypic traits, and allelic variation in LpNHX1 may affect salinity tolerance of perennial ryegrass. 相似文献
214.
In general, optimal reaction norms in heterogeneous populations can be obtained only by iterative numerical procedures (McNamara,
1991; Kawecki and Stearns, 1993). We consider two particular, but biologically plausible and analytically tractable cases
of individual optimization to gain insight into the mechanisms which shape the optimal reaction norm of fecundity in relation
to an environmental variable or an individual trait. In the first case, we assume that the quality of the environment (e.g.
food abundance) or the quality of the individual (e.g. body size) is fixed during its entire life; it may also be a heritable
individual trait. In the second case, individual quality is assumed to change randomly such that the probability distribution
of quality in the next year is the same for the parent and for her offspring. For these two cases, we obtain analytical expressions
for the shape of the optimal reaction norm, which are heuristically interpretable in terms of underlying selective mechanisms.
It is shown that better quality may reduce the optimal fecundity. This outcome is particularly likely if better quality increases
a fecundity-independent factor of parental survival in a long-lived species with fixed quality.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
215.
Diagnostic self‐testing devices are being developed for many illnesses, chronic diseases and infections. These will be used in hospitals, at point‐of‐care facilities and at home. Designed to allow earlier detection of diseases, self‐testing diagnostic devices may improve disease prevention, slow the progression of disease and facilitate better treatment outcomes. These devices have the potential to benefit both the individual and society by enabling individuals to take a more proactive role in the maintenance of their health and by helping society improve health and reduce health costs. However, the full implications of future home‐based diagnostic technology for individuals and society remain unclear due to their novelty. We argue that the development of diagnostic tools, especially for home use, will heighten a number of ethical challenges. This paper will explore some of the ethical implications of home‐based self‐testing diagnostic devices for the autonomous and relational dimensions of the person. This will be facilitated by examining the impact of diagnostic devices for individual autonomy, for the delivery of accurate diagnosis and for the personal significance of the information for the user. The latter will be examined using Charles Taylor's view of personhood and his emphasis on human agency and interpretation. While the ethical issues are not necessarily new, the development of home‐based self‐testing diagnostic devices will make issues regarding autonomy, accuracy of information and personal significance more and more demanding. This will be the case particularly when an individual's autonomous choices come into conflict with the person's relational responsibilities. 相似文献
216.
奥陶纪是串管海绵早期演化的一个关键阶段,记录了该类群的首次大规模辐射演化事件(属级分类单元达15个)。然而,现有大部分奥陶系串管海绵的报道来自澳大利亚东部和北美等地,在中国至今仅发现了两个属,与前述地区相比研究程度偏低。早期研究主要基于形态学特征对串管海绵进行系统分类描述,对其滤食策略知之甚少,因此制约了对此类海绵在奥陶纪底栖生态系统作用的相关探讨。本文系新疆塔里木柯坪地区奥陶纪串管海绵的首次系统古生物学报道,详细描述凯迪阶(上奥陶统)印干组中保存完好的阔室丛花海绵(Corymbospongia amplia)化石的形态学特征,并通过研究标本外壁微孔孔径的大小分布,探讨其滤食选择性。海绵外壁微孔孔径的分析表明:小型和微型浮游生物可能是其食物的主要来源,而多细胞浮游动物因个体尺寸大于海绵外壁微孔,不能被阔室丛花海绵捕获。本研究为奥陶纪串管海绵古生态学及其地球生物学意义的探讨提供了进一步的依据。 相似文献
217.
Isolation and Preliminary Characterization of Hydroxamic Acids Formed by Nitrogen-Fixing Azotobacter chroococcum B-8 下载免费PDF全文
Frank A. Fekete Richard A. Lanzi John B. Beaulieu David C. Longcope Andrew W. Sulya Roger N. Hayes Gary A. Mabbott 《Applied microbiology》1989,55(2):298-305
The free-living diazotroph Azotobacter chroococcum B-8 responded to iron-limited growth conditions by forming hydroxamic acids and an 85,000-dalton outer membrane protein. The Fe(III)-binding hydroxamate compounds stimulated the growth of Arthrobacter flavescens JG-9 and gave a positive Csaky reaction for bound hydroxylamines. The hydroxamates were isolated from liquid cultures by benzyl alcohol extraction and purified by size exclusion chromatography and high-performance liquid chromatography. Four high-performance liquid chromatography fractions, designated A, B, C, and D, had the characteristic hydroxamate absorption maximum at 420 to 423 nm, which did not shift over a pH range from 3.0 to 9.0. Cyclic voltammograms of the iron-hydroxamate complexes exhibited reduction potentials of −0.426 to −0.442 V for fractions A, B, and D and of −0.56 V for fraction C versus the normal hydrogen electrode at pH 8.0. Based on mass spectra, nominal molecular weights of 800 and 844 were assigned to ferrated compounds A and B, respectively. Reductive hydrolysis of compounds A and B in 57% hydriodic acid yielded ornithine as detected by gas chromatography-mass spectrometry. All of these physiological and chemical data strongly support the hypothesis that the high-affinity iron-binding compounds isolated from A. chroococcum B-8 are hydroxamic acids and probably function as siderophores for this diazotroph. 相似文献