全文获取类型
收费全文 | 83篇 |
免费 | 10篇 |
出版年
2022年 | 1篇 |
2021年 | 2篇 |
2020年 | 1篇 |
2018年 | 2篇 |
2017年 | 4篇 |
2016年 | 5篇 |
2015年 | 7篇 |
2014年 | 5篇 |
2013年 | 5篇 |
2012年 | 7篇 |
2011年 | 5篇 |
2010年 | 4篇 |
2009年 | 6篇 |
2008年 | 3篇 |
2007年 | 2篇 |
2006年 | 2篇 |
2005年 | 1篇 |
2004年 | 1篇 |
2003年 | 1篇 |
2002年 | 2篇 |
2001年 | 1篇 |
2000年 | 1篇 |
1999年 | 3篇 |
1998年 | 4篇 |
1997年 | 3篇 |
1996年 | 2篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1992年 | 1篇 |
1987年 | 1篇 |
1986年 | 4篇 |
1985年 | 1篇 |
1978年 | 1篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1970年 | 1篇 |
排序方式: 共有93条查询结果,搜索用时 910 毫秒
81.
Bacterioplankton Dynamics in the McMurdo Dry Valley Lakes, Antarctica: Production and Biomass Loss over Four Seasons 总被引:4,自引:0,他引:4
Abstract Research of the microbial ecology of McMurdo Dry Valley lakes has concentrated primarily on phototrophs; relatively little is known about the heterotrophic bacterioplankton. Bacteria represent a substantial proportion of water column biomass in these lakes, comprising 30 to 60% of total microplankton biomass. Bacterial production and cell numbers were measured 3 to 5 times, within four Antarctic seasons (October to January), in Lakes Fryxell, Hoare, and Bonney. The winter-spring transition (September to October) was included during one year. Lake Fryxell was the most productive, but variable, lake, followed by Lakes Bonney and Hoare. Bacterial production ranged from 0 to 0.009 μg C ml-1 d-1; bacterial populations ranged from 3.2 x 10(4) to 4.4 x 10(7) cells ml-1. Bacterial production was always greatest just below the ice cover at the beginning of the season. A second maximum developed just above the chemocline of all the lakes, as the season progressed. Total bacterioplankton biomass in the lakes decreased as much as 88% between successive sampling dates in the summer, as evidenced by areal integration of bacterial populations; the largest decreases in biomass typically occurred in mid-December. A forward difference model of bacterial loss in the trophogenic zone and the entire water column of these lakes showed that loss rates in the summer reached 6.3 x 10(14) cells m-2 d-1 and 4.16 x 10(12) cells m-2 d-1, respectively. These results imply that bacteria may be a source of carbon to higher trophic levels in these lakes, through grazing. 相似文献
82.
拐芹根化学成分研究Ⅱ 总被引:3,自引:0,他引:3
从伞型科当归属植物拐芹(Angelica polymorpha Maxim)的根及根茎中又分得4个结晶性化合物。经物理常数测定、光谱分析,分别鉴定为欧前胡素Ⅰ,异氧化前胡内酯Ⅱ,Pabulenol Ⅲ,Phellopterin Ⅳ。 相似文献
83.
Fätkenheuer G Pozniak AL Johnson MA Plettenberg A Staszewski S Hoepelman AI Saag MS Goebel FD Rockstroh JK Dezube BJ Jenkins TM Medhurst C Sullivan JF Ridgway C Abel S James IT Youle M van der Ryst E 《Nature medicine》2005,11(11):1170-1172
We assessed the efficacy and safety of 10-d monotherapy with the orally administered CCR5 antagonist maraviroc in 63 HIV-1-positive individuals prescreened for the absence of CXCR4-using virus. Maximum reduction in viral load occurred at a median of 10-15 d, with a mean reduction of >or=1.6 log(10) copies/ml at all twice daily doses >or=100 mg. These results provide proof of concept that CCR5 antagonism is a viable antiretroviral therapeutic approach. 相似文献
84.
Jemanesh K. Haile Amidou N’Diaye Fran Clarke John Clarke Ron Knox Jessica Rutkoski Filippo M. Bassi Curtis J. Pozniak 《Molecular breeding : new strategies in plant improvement》2018,38(6):75
The prediction accuracies of genomic selection depend on several factors, including the genetic architecture of target traits, the number of traits considered at a given time, and the statistical models. Here, we assessed the potential of single-trait (ST) and multi-trait (MT) genomic prediction models for durum wheat on yield and quality traits using a breeding panel (BP) of 170 varieties and advanced breeding lines, and a doubled-haploid (DH) population of 154 lines. The two populations were genotyped with the Infinium iSelect 90K SNP assay and phenotyped for various traits. Six ST-GS models (RR-BLUP, G-BLUP, BayesA, BayesB, Bayesian LASSO, and RKHS) and three MT prediction approaches (MT-BayesA, MT-Matrix, and MT-SI approaches which use economic selection index as a trait value) were applied for predicting yield, protein content, gluten index, and alveograph measures. The ST prediction accuracies ranged from 0.5 to 0.8 for the various traits and models and revealed comparable prediction accuracies for most of the traits in both populations, except BayesA and BayesB, which better predicted gluten index, tenacity, and strength in the DH population. The MT-GS models were more accurate than the ST-GS models only for grain yield in the BP. Using BP as a training set to predict the DH population resulted in poor predictions. Overall, all the six ST-GS models appear to be applicable for GS of yield and gluten strength traits in durum wheat, but we recommend the simple computational models RR-BLUP or G-BLUP for predicating single trait and MT-SI for predicting yield and protein simultaneously. 相似文献
85.
86.
Identification of QTL and association of a phytoene synthase gene with endosperm colour in durum wheat 总被引:6,自引:6,他引:0
Pozniak CJ Knox RE Clarke FR Clarke JM 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2007,114(3):525-537
The yellow colour of durum wheat (Triticum turgidum L. var durum) semolina is due in part to the presence of carotenoid pigments found in the endosperm and is an important end-use quality trait. We hypothesized that variation in the genes coding for phytoene synthase (Psy), a critical enzyme in carotenoid biosynthesis, may partially explain the phenotypic variation in endosperm colour observed among durum cultivars. Using rice sequence information, primers were designed to PCR clone and sequence the Psy genes from Kofa (high colour) and W9262-260D3 (medium colour) durum cultivars. Sequencing confirmed the presence of four Psy genes in each parent, corresponding to a two member gene family designated as Psy1-1, Psy1-2 and Psy2-1 and Psy2-2. A genetic map was constructed using 155 F1-derived doubled haploid lines from the cross W9262-260D3/Kofa with 194 simple sequence repeat and DArT markers. Using Psy1-1 and Psy2-1 allele-specific markers and chromosome mapping, the Psy1 and Psy2 genes were located to the group 7 and 5 chromosomes, respectively. Four quantitative trait loci (QTL) underlying phenotypic variation in endosperm colour were identified on chromosomes 2A, 4B, 6B, and 7B. The Psy1-1 locus co-segregated with the 7B QTL, demonstrating an association of this gene with phenotypic variation for endosperm colour. This work is the first report of mapping Psy genes and supports the role of Psy1-1 in elevated levels of endosperm colour in durum wheat. This gene is a target for the further development of a molecular marker to enhance selection for endosperm colour in durum wheat breeding programs. 相似文献
87.
Our study was designed to examine how components of complex mixtures can
inhibit the binding of other components to receptor sites in the olfactory
system of the spiny lobster Panulirus argus. Biochemical binding assays
were used to study how two- to six-component mixtures inhibit binding of
the radiolabeled odorants taurine, L-glutamate and
adenosine-5'-monophosphate to a tissue fraction rich in dendritic membrane
of olfactory receptor neurons. Our results indicate that binding inhibition
by mixtures can be large and is dependent on the nature of the odorant
ligand and on the concentration and composition of the mixture. The binding
inhibition by mixtures of structurally related components was generally
predicted using a competitive binding model and binding inhibition data for
the individual components. This was not the case for binding inhibition by
most mixtures of structurally unrelated odorants. The binding inhibition
for these mixtures was generally smaller than that for one or more of their
components, indicating that complex binding interactions between components
can reduce their ability to inhibit binding. The magnitude of binding
inhibition was influenced more by the mixture's precise composition than by
the number of components in it, since mixtures with few components were
sometimes more inhibitory than mixtures with more components. These
findings raise the possibility that complex binding interactions between
components of a mixture and their receptors may shape the output of
olfactory receptor neurons to complex mixtures.
相似文献
88.
89.
A case of primary malignant lymphoma of the heart diagnosed cytologically is reported. The patient presented with pericardial tamponade and ventricular arrhythmias and developed rapidly progressive and intractable cardiac failure. Two-dimensional echo-cardiography, which demonstrated the pericardial effusion, showed progressive impairment of the left ventricular contraction. The pericardial fluid contained malignant lymphoid cells. Despite vigorous treatment and chemotherapy, the patient died within 15 days; postmortem examination showed malignant lymphoma confined to the myocardium. 相似文献
90.