全文获取类型
收费全文 | 348篇 |
免费 | 22篇 |
出版年
2023年 | 4篇 |
2022年 | 7篇 |
2021年 | 18篇 |
2020年 | 12篇 |
2019年 | 5篇 |
2018年 | 18篇 |
2017年 | 7篇 |
2016年 | 14篇 |
2015年 | 11篇 |
2014年 | 12篇 |
2013年 | 22篇 |
2012年 | 36篇 |
2011年 | 38篇 |
2010年 | 16篇 |
2009年 | 10篇 |
2008年 | 41篇 |
2007年 | 35篇 |
2006年 | 11篇 |
2005年 | 22篇 |
2004年 | 5篇 |
2003年 | 6篇 |
2002年 | 2篇 |
2001年 | 4篇 |
1999年 | 1篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1994年 | 1篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1987年 | 1篇 |
1982年 | 1篇 |
1971年 | 2篇 |
1970年 | 1篇 |
1968年 | 1篇 |
1966年 | 1篇 |
排序方式: 共有370条查询结果,搜索用时 15 毫秒
131.
Feruloylation and structure of arabinoxylan in wheat endosperm cell walls from RNAi lines with suppression of genes responsible for backbone synthesis and decoration 下载免费PDF全文
Jackie Freeman Jane L. Ward Ondrej Kosik Alison Lovegrove Mark D. Wilkinson Peter R. Shewry Rowan A.C. Mitchell 《Plant biotechnology journal》2017,15(11):1429-1438
Arabinoxylan (AX) is the major component of the cell walls of wheat grain (70% in starchy endosperm), is an important determinant of end‐use qualities affecting food processing, use for animal feed and distilling and is a major source of dietary fibre in the human diet. AX is a heterogeneous polysaccharide composed of fractions which can be sequentially extracted by water (WE‐AX), then xylanase action (XE‐AX) leaving an unextractable (XU‐AX) fraction. We determined arabinosylation and feruloylation of AX in these fractions in both wild‐type wheat and RNAi lines with decreased AX content (TaGT43_2 RNAi, TaGT47_2 RNAi) or decreased arabinose 3‐linked to mono‐substituted xylose (TaXAT1 RNAi). We show that these fractions are characterized by the degree of feruloylation of AX, <5, 5–7 and 13–19 mg bound ferulate (g?1 AX), and their content of diferulates (diFA), <0.3, 1–1.7 and 4–5 mg (g?1 AX), for the WE, XE and XU fractions, respectively, in all RNAi lines and their control lines. The amount of AX and its degree of arabinosylation and feruloylation were less affected by RNAi transgenes in the XE‐AX fraction than in the WE‐AX fraction and largely unaffected in the XU‐AX fraction. As the majority of diFA is associated with the XU‐AX fraction, there was only a small effect (TaGT43_2 RNAi, TaGT47_2 RNAi) or no effect (TaXAT1 RNAi) on total diFA content. Our results are compatible with a model where, to maintain cell wall function, diFA is maintained at stable levels when other AX properties are altered. 相似文献
132.
Summary Compositional variations and grain-size properties of both carbonate constituents and conodonts as an alternative component
group were used for interpreting the processes governing the deposition of upper Famennian and middle Tournaisian calciturbidites
in Moravia, Czech Republic. Both the composition and grain-size properties of conodont element associations showed to be markedly
dependant on facies type of their host sediment. Upper Devonian calciturbidite successions deposited on flanks of wide, Moravian-Silesian
carbonate platform are composed mainly of echinoderm-and peloid-rich wacke/packstones and intraclastic float/rudstones (fine-grained
calciturbidites, “normal” calciturbidites with Tab Bouma sequences, debris-flow breccias) with abundance of shelf-and shelf
margin conodont taxa and epipelagic and “mesopelagic” conodonts. Upper Devonian calciturbidites deposited on slopes of volcanic
sea-mounts are composed of echinoderm-and peloid-rich wacke/packstones and float/rudstones with increased proportion of intraclasts
and volcanigenic lithoclasts (fine-grained calciturbidites, normal calciturbidites), yeilding abundant conodont associations
with higher proportion of “mesopelagic” taxa compared to the platform-flank examples. Middle Tournaisian calciturbidite succession
composed of crinoid-, peloid-, intraclast-and lithoclast-rich lime mudstones, wacke/packstones and float/rudstones (normal
calciturbidites and debris-flow breccias) yielded conodont element associations rich in shelt-and shelf-margin taxa, “mesopelagic”
conodonts and reworked Middle-and Upper Devonian conodonts.
In general, the ratio of shelf-and shelf margin conodont taxa to “mesopelagic” taxa is distinctly lower in finegrained calciturbidites
than it is in normal calciturbidites and debris-flow breccias. Grain-size properties (mean grain size and sorting) and percentage
of fragmented conodont elements, too, are markedly dependant on the facies type: in fine-grained calciturbidites the values
of mean grain-size and fragmentation are low and the sorting is good to very good whereas in normal calciturbidites and debris-flow
breccias the values of mean grain-size and fragmentation are distinctly higher and the sorting is poorer. The interdependence
of facies type and composition and grain-size properties of conodont element associations in gravity-flow deposits is explained
as resultant from hydrodynamic sorting during turbidity current flow and final deposition of the bed. Compositional variations
observed in our sections may thus be attributed to facies variability (coarsening-and thickening-upward trends) rather than
to sea-level fluctuations (highstand shedding of carbonate platforms). On the other hand, significant enrichment in reworked
conodont taxa in middle Tournaisian normal calciturbidites compared to scarcity and/or absence of such conodonts in essentially
identical facies of upper Famennian age indicate sea-level to be the major control governing such compositional variations,
with low relative sea-level stand in middle Tournaisian and high relative sea-level stand in upper Famennian. Thorough analysis
of conodont evolution, palaeoecology and taphonomy, with emphasis on understanding the processes of deposition of their host
rock, are recommended for any biostratigraphic and biofacies study to be done in carbonate sediments deposited under strong
hydrodynamic regimes, such as calciturbidites, temperstites, debris-flow deposits, shelf-edge oolitic sands, tidal-channel
facies etc. 相似文献
133.
Rego RO Hajdusek O Kovár V Kopácek P Grubhoffer L Hypsa V 《Insect biochemistry and molecular biology》2005,35(9):991-1004
Among disease-vectors, the evolution of the tick innate immune system is still lagging when compared to insects. Such an investigation, which was initiated, by first cloning and sequencing lectins associated in the innate immunity of invertebrates and having fibrinogen related domains, helped in the sequencing of cDNA encoding for OMFREP from the soft tick, Ornithodoros moubata. Also obtained were Ixoderin A and Ixoderin B cDNA sequences from the hard tick Ixodes ricinus. Tissue-specific expression of OMFREP showed that it was present primarily in the hemocytes and salivary glands. Ixoderin A besides sharing a similar expression profile was also expressed in the midgut. Both showed significantly high homology to the lectin Dorin M, from O. moubata. Further, phylogenetic comparisons between these molecules of the soft and hard ticks showed their relatedness to Tachylectins 5A and 5B, involved in the innate immunity of Tachypleus tridentatus and ficolins from both vertebrates and invertebrates. Ixoderin B showing tissue-specific expression only in the salivary glands and the sequence displaying certain motif differences in homology point towards a possible function different from the other two molecules. This is the first report of lectin-like sequences, with a fibrinogen-domain, from the hard tick I. ricinus and a preliminary phylogenetic study of these tick sequences with related fibrinogen-domain containing sequences highlights a possible role for them in the innate immunity of the ticks. 相似文献
134.
Lisy O Redfield MM Schirger JA Burnett JC 《American journal of physiology. Regulatory, integrative and comparative physiology》2005,288(1):R158-R162
The goal of the study was to define the effect of chronic unloading of the normal heart on atrial endocrine function with a focus on brain natriuretic peptide (BNP), specifically addressing the role of load and neurohumoral stimulation. Although produced primarily by atrial myocardium in the normal heart, controversy persists with regard to load-dependent vs. neurohumoral mechanisms controlling atrial BNP synthesis and storage. We used a unique canine model of chronic unloading of the heart produced by thoracic inferior vena caval constriction (TIVCC), which also resulted in activation of plasma endothelin (ET-1), ANG II, and norepinephrine (NE), known activators of BNP synthesis, compared with sham. TIVCC was produced by banding of the inferior vena cava for 10 days (n = 6), whereas in control (n = 5) the band was not constricted (sham). In a third group (n = 7), the band was released on day 11, thus acutely reloading the heart. Chronic TIVCC decreased cardiac output and right atrial pressure with a decrease in atrial mass index consistent with atrial atrophy. Atrial BNP mRNA decreased compared with sham. Immunoelectron microscopy revealed an increase in BNP in atrial granules consistent with increased storage. Acute reloading increased cardiac filling pressures and resulted in an increase in plasma BNP. We conclude that chronic unloading of the normal heart results in atrial atrophic remodeling and in suppression of atrial BNP mRNA despite intense stimulation by ET, ANG II, and NE, underscoring the primacy of load in the control of atrial endocrine function and structure. 相似文献
135.
Petr Ostadal David Alan Petr Hajek Jiri Vejvoda Martin Mates Peter Blasko Josef Veselka Milan Kvapil Jiri Kettner Martin Wiendl Ondrej Aschermann Josef Slaby Eduard Nemecek Frantisek Holm Marek Rac Milan Macek Jana Cepova 《Trials》2005,6(1):1-6
Background
Stent length serves as a predictor of restenosis in use of bare metal stents (BMS). This has been demonstrated in a feasibility study that used a single short BMS implant (<9 mm) in a high proportion of lesions; the study observed a low rate of restenosis.Methods
We performed a pilot prospective study to investigate in a series of consecutive patients the immediate and long-term effects of implantation of either 1) a single short BMS for all lesions with low probability of restenosis or 2) a drug-eluting stent (DES) for all other lesions.Results
The 200 patients studied had 236 coronary artery lesions that were treated with short BMS in 168/236 patients (71.2%) and with DES in 68/236 patients (28.8%). Angiographic success was achieved in 230/236 lesions (97.5%) and procedural success in 194/200 patients (97.0%). Restenosis occurred in 15/153 lesions (9.8%) after short BMS, in 3/62 lesions (4.8%) after DES, and in 18/215 of all lesions (8.4%) angiographically controlled after six to eight months. Target vessel revascularization was performed in 16/218 lesion (7.4%).Conclusion
Most of the coronary artery lesions in this small group of consecutive patients were treated sufficiently with a single BMS implant. This differential approach of treating suitable lesions in medium- to large-sized vessels with a single short BMS device and treating all other lesions with a DES implant resulted in a low incidence of restenosis. 相似文献136.
137.
138.
Strong homeostatic TCR signals induce formation of self‐tolerant virtual memory CD8 T cells 下载免费PDF全文
Daniel Mueller Martina Huranova Veronika Horkova Michaela Pribikova Robert Ivanek Susanne Oberle Dietmar Zehn Kathy D McCoy Peter Draber Ondrej Stepanek 《The EMBO journal》2018,37(14)
Virtual memory T cells are foreign antigen‐inexperienced T cells that have acquired memory‐like phenotype and constitute 10–20% of all peripheral CD8+ T cells in mice. Their origin, biological roles, and relationship to naïve and foreign antigen‐experienced memory T cells are incompletely understood. By analyzing T‐cell receptor repertoires and using retrogenic monoclonal T‐cell populations, we demonstrate that the virtual memory T‐cell formation is a so far unappreciated cell fate decision checkpoint. We describe two molecular mechanisms driving the formation of virtual memory T cells. First, virtual memory T cells originate exclusively from strongly self‐reactive T cells. Second, the stoichiometry of the CD8 interaction with Lck regulates the size of the virtual memory T‐cell compartment via modulating the self‐reactivity of individual T cells. Although virtual memory T cells descend from the highly self‐reactive clones and acquire a partial memory program, they are not more potent in inducing experimental autoimmune diabetes than naïve T cells. These data underline the importance of the variable level of self‐reactivity in polyclonal T cells for the generation of functional T‐cell diversity. 相似文献
139.
140.