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121.
Recent studies have variably reported that tumour necrosis factor alpha (TNF-alpha) induces either necrosis or apoptosis in L929 cells. This study was undertaken to better characterize the mode of death induced in L929 cells by this agent. We determined the effects of exposure to TNF-alpha and other cytotoxic agents on cell size and morphology, cell membrane permeability, exposure of phosphatidylserine at the cell surface, nuclear morphology and fragmentation of DNA. Our results suggest that L929 cells treated with TNF-alpha alone show nuclear changes and a pattern of DNA fragmentation that are atypical of apoptosis. In contrast, our results demonstrate that, when augmented with actinomycin D, TNF-alpha induces classical apoptosis in L929 cells. We also provide the first report that, in L929 cells, staurosporine induces classical apoptosis and colchicine induces a form of apoptosis lacking internucleosomal DNA fragmentation. Previous studies of TNF-alpha-induced death in L929 cells relied on measurements of only one or two parameters to define the mode of death. Overall, our results suggest that in future cellular or biochemical studies of the effects of TNF-alpha on L929 cells it will be prudent to characterize the mode of death in each case using a multi-parameter approach, as done here. 相似文献
122.
In Expt 1, plants of tall fescue (Festuca arundinacea
Schreb.), Italian ryegrass (Lolium multiflorum Lam.)
and their F1 hybrid were grown in soil-based compost in a controlled
environment, and subjected to full or partial irrigation for 20 d. In Expt
2, plants of the parent species were grown in nutrient solution in the same
environment and subjected to osmotic stress (0.76 MPa) for 2 d. In both
experiments, distribution of growth in the leaf growing zone (at the base
of the growing leaf) was determined, and elastic and plastic compliances
were measured on methanol-killed samples of growing zone and of mature
lamina using an extensiometer. In Expt 2 plastic compliance coefficient of
extension, extensibility, and hydraulic conductance were calculated from
changes in leaf extension rate occasioned by imposing linear stress.
'Plastic and elastic compliances of growing zones were 10-20 times greater
than those of mature laminae. In both species, drought reduced (a) leaf
extension rate, (b) the length of the growing zone, the height of maximum
growth, (d) the plastic compliance of whole bases (Expt 1), and (e)
hydraulic conductance. The elastic compliance of whole leaf bases was
unaffected by drought, but when expressed per unit length of growing zone
was increased by drought. Killing with methanol reduced the plastic
compliance of leaf bases in control plants, but not in droughted
plants.F. arundinacea differed from L.
multiflorum in having (a) a lower leaf extension rate (although
drought reduced extension by the same proportion in both species), (b) a
longer growing zone in droughted plants in Expt 2, a lower elastic and
plastic compliance of whole killed leaf bases and laminae, (d) slightly
higher plastic compliance in attached growing leaves, and (e) lower plastic
compliance per unit length of growing zone in attached leaves. The hybrid
was generally intermediate between the parents. the results are discussed
in relation to methodology and to crop improvement.Key
words: Extensibility, extension coefficient, hydraulic
conductance, elastic compliance, plastic compliance, leaf growth, leaf
extension rate.
相似文献
123.
J Bülow L Simonsen D Wiggins S M Humphreys K N Frayn D Powell G F Gibbons 《Journal of lipid research》1999,40(11):2034-2043
The integration of lipid metabolism in the splanchnic bed and in subcutaneous adipose tissue before and after ingestion of a 75 g glucose load was studied by Fick's principle in seven healthy subjects. Six additional subjects were studied during a hyperinsulinemic euglycemic clamp. Release of non-esterified fatty acids (NEFA) from adipose tissue and splanchnic NEFA extraction followed a similar time-course after oral glucose, and there was a highly significant relationship between adipose tissue NEFA release and splanchnic NEFA uptake. There was no immediate inhibition of splanchnic very low density lipoprotein (VLDL)-triacylglycerol (TAG) output when plasma insulin levels increased after glucose. Adipose tissue extraction of VLDL-TAG tended to vary in time in a manner similar to splanchnic VLDL-TAG output and the two were significantly related. The area-under-curves (AUC) for splanchnic extraction of NEFA was significantly lower than that for output of VLDL, implying depletion of hepatic TAG stores during the experiment. In the hyperinsulinemic clamp experiments, there was on average suppression of splanchnic VLDL-TAG output although between-person variability was marked. This suppression could be explained by a very low supply of NEFA during the clamp.We conclude that there is an integrated pattern of metabolism in splanchnic and adipose tissues in the postabsorptive and post-glucose states. Flux of NEFA from adipose tissue drives splanchnic NEFA uptake. Splanchnic VLDL-TAG secretion appears to be regulated by a number of factors and in turn controls TAG extraction in adipose tissue. Insulin does not seem to play a key role in the acute regulation of hepatic VLDL metabolism under these particular conditions in vivo. 相似文献
124.
Glyn W.Humphreys 《中国科学:生命科学英文版》2005,48(2):106-116
In order to perceive complex visual scenes, the human perceptual system has to organize discrete enti-ties in the visual field into chunks or perceptual units for higher-level processing. Perceptual organization is governed by Gestalt principles such as proximity, similarity, and continuity[1]. Thus spatially close ob-jects tend to be grouped together, as do elements that are similar to one another. Grouping based on the Ge-stalt laws (particularly proximity) is critical for the perception of… 相似文献
125.
Bruno Studer Torben Asp Ursula Frei Stephan Hentrup Helena Meally Aurélie Guillard Susanne Barth Hilde Muylle Isabel Roldán-Ruiz Philippe Barre Carole Koning-Boucoiran Gerda Uenk-Stunnenberg Oene Dolstra Leif Skøt Kirsten P. Skøt Lesley B. Turner Mervyn O. Humphreys Roland Kölliker Niels Roulund Klaus K. Nielsen Thomas Lübberstedt 《Molecular breeding : new strategies in plant improvement》2008,21(4):533-548
An expressed sequence tag (EST) library of the key grassland species perennial ryegrass (Lolium perenne L.) has been exploited as a resource for microsatellite marker development. Out of 955 simple sequence repeat (SSR) containing
ESTs, 744 were used for primer design. Primer amplification was tested in eight genotypes of L. perenne and L. multiflorum representing (grand-) parents of four mapping populations and resulted in 464 successfully amplified EST-SSRs. Three hundred
and six primer pairs successfully amplified products in the mapping population VrnA derived from two of the eight genotypes
included in the original screening and revealed SSR polymorphisms for 143 ESTs. Here, we report on 464 EST-derived SSR primer
sequences of perennial ryegrass established in laboratory assays, providing a dedicated tool for marker assisted breeding
and comparative mapping within and among forage and turf grasses.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
126.
Jifeng Tang Samantha J Baldwin Jeanne ME Jacobs C Gerard van der Linden Roeland E Voorrips Jack AM Leunissen Herman van Eck Ben Vosman 《BMC bioinformatics》2008,9(1):374
Background
Simple Sequence Repeat (SSR) or microsatellite markers are valuable for genetic research. Experimental methods to develop SSR markers are laborious, time consuming and expensive. In silico approaches have become a practicable and relatively inexpensive alternative during the last decade, although testing putative SSR markers still is time consuming and expensive. In many species only a relatively small percentage of SSR markers turn out to be polymorphic. This is particularly true for markers derived from expressed sequence tags (ESTs). In EST databases a large redundancy of sequences is present, which may contain information on length-polymorphisms in the SSR they contain, and whether they have been derived from heterozygotes or from different genotypes. Up to now, although a number of programs have been developed to identify SSRs in EST sequences, no software can detect putatively polymorphic SSRs. 相似文献127.
Jeanine A Verbunt Henk AM Seelen Feljandro P Ramos Bernard HM Michielsen Wim L Wetzelaer Martine Moennekens 《BMC neurology》2008,8(1):7
Background
Over 50% of patients with upper limb paresis resulting from stroke face long-term impaired arm function and ensuing disability in daily life. Unfortunately, the number of effective treatments aimed at improving arm function due to stroke is still low. This study aims to evaluate a new therapy for improving arm function in sub-acute stroke patients based on mental practice theories and functional task-oriented training, and to study the predictors for a positive treatment result. It is hypothesized that a six-week, mental practice-based training program (additional to regular therapy) targeting the specific upper extremity skills important to the individual patient will significantly improve both arm function and daily activity performance, as well as being cost effective. 相似文献128.
Ellsworth BA Meng W Patel M Girotra RN Wu G Sher PM Hagan DL Obermeier MT Humphreys WG Robertson JG Wang A Han S Waldron TL Morgan NN Whaley JM Washburn WN 《Bioorganic & medicinal chemistry letters》2008,18(17):4770-4773
Inhibition of sodium-dependent glucose transporter 2 (SGLT2), the transporter that is responsible for renal re-uptake of glucose, leads to glucosuria in animals. SGLT-mediated glucosuria provides a mechanism to shed excess plasma glucose to ameliorate diabetes-related hyperglycemia and associated complications. The current study demonstrates that the proper relationship of a 4′-substituted benzyl group to a β-1C-phenylglucoside is important for potent and selective SGLT2 inhibition. The lead C-arylglucoside (7a) demonstrates superior metabolic stability to its O-arylglucoside counterpart (4) and it promotes glucosuria when administered in vivo. 相似文献
129.
Subterranean or groundwater estuaries occur in porous and cavernous substrates where groundwater abuts the ocean. Like surface
estuaries, they are strongly stratified, temporally and hydrochemically heterogeneous environments that support complex hydrogeochemical
and biological processes and ecological communities. Here, we contend that groundwater estuaries also occur where groundwater
flow approaches salt lakes and provide evidence in the context of groundwater (valley or phreatic) calcretes in palaeovalleys
of the arid western plateau of Australia. The calcrete groundwater estuaries display marked and complex physico-chemical gradients
along, across and through the groundwater flow path. From the first principles and the density differences between water bodies,
we may expect the form and dynamics of the saltwater front to mimic that of marine estuaries but with the dynamic and temporal
response to changing hydrology heavily dampened, and driven by the episodic groundwater recharge and lake filling typical
of arid regions. The calcrete aquifers support diverse biological communities of obligate groundwater animals, largely endemic
to a given calcrete body. These communities comprise both macro and microinvertebrates, predominantly a suite of crustacean
higher taxa, and a great diversity of diving beetles (Dytiscidae) isolated in the calcrete aquifers between ca. 5 and 8 million
years ago.
Guest Editors: J. John & B. Timms
Salt Lake Research: Biodiversity and Conservation—Selected papers from the 9th Conference of the International Society for
Salt Lake Research
An erratum to this article can be found at 相似文献
130.
Isla Humphreys Vicki Fleming Paolo Fabris Joe Parker Bodo Schulenberg Anthony Brown Charis Demetriou Silvana Gaudieri Katja Pfafferott Michaela Lucas Jane Collier Kuan-Hsiang Gary Huang Oliver G. Pybus Paul Klenerman Eleanor Barnes 《Journal of virology》2009,83(22):11456-11466
Hepatitis C virus subtype 3a is a highly prevalent and globally distributed strain that is often associated with infection via injection drug use. This subtype exhibits particular phenotypic characteristics. In spite of this, detailed genetic analysis of this subtype has rarely been performed. We performed full-length viral sequence analysis in 18 patients with chronic HCV subtype 3a infection and assessed genomic viral variability in comparison to other HCV subtypes. Two novel regions of intragenotypic hypervariability within the envelope protein E2, of HCV genotype 3a, were identified. We named these regions HVR495 and HVR575. They consisted of flanking conserved hydrophobic amino acids and central variable residues. A 5-amino-acid insertion found only in genotype 3a and a putative glycosylation site is contained within HVR575. Evolutionary analysis of E2 showed that positively selected sites within genotype 3a infection were largely restricted to HVR1, HVR495, and HVR575. Further analysis of clonal viral populations within single hosts showed that viral variation within HVR495 and HVR575 were subject to intrahost positive selecting forces. Longitudinal analysis of four patients with acute HCV subtype 3a infection sampled at multiple time points showed that positively selected mutations within HVR495 and HVR575 arose early during primary infection. HVR495 and HVR575 were not present in HCV subtypes 1a, 1b, 2a, or 6a. Some variability that was not subject to positive selection was present in subtype 4a HVR575. Further defining the functional significance of these regions may have important implications for genotype 3a E2 virus-receptor interactions and for vaccine studies that aim to induce cross-reactive anti-E2 antibodies.Hepatitis C virus (HCV) infection is a major global health issue leading to persistent viral infection in the majority of those infected and is associated with progressive liver disease, cirrhosis, and hepatocellular carcinoma. Six major genotypes of HCV have been described that have evolved in geographically distinct regions and that share approximately. 80% nucleotide homology with one another. HCV viral genotypes have been further classified into subtypes (25). HCV subtype 3a infection is now the most common subtype in the United Kingdom (11), although it is globally distributed and frequently associated with intravenous drug use.The classification of HCV viral strains by genotype and subtype has proven informative not only in terms of the epidemic and evolutionary history of the virus but also in terms of clinical outcomes. In particular, the response rates to current gold standard therapy (9) and the prevalence of hepatic steatosis (20) are significantly higher for subtype 3a than for genotype 1 infections. The reasons for this are not understood but must relate to viral genetic and phenotypic differences between strains, or to differences in the ability of hosts to exert an effective immune response against particular viral sequences, or to a combination of both factors.To date, detailed assessment of the HCV genome has largely focused on HCV genotype 1. Indeed, only a few full-length HCV subtype 3a viral sequences are currently published and available within the major HCV databases (Los Alamos; http://hcv.lanl.gov/components/hcv-db/combined_search/searchi.html and euHCVdb; http://euhcvdb.ibcp.fr/euHCVdb/) (16).To characterize HCV subtype 3a in detail, we performed whole-genome analysis of a cohort of patients with persistent HCV subtype 3a infection. We subsequently focus on the highly variable regions observed in the envelope protein E2 in both acute and chronic infection, since it was apparent that these regions were not restricted to the well-documented hypervariable region 1 (HVR1) that is found at the 5′ end of E2 in all HCV genotypes.Viral genomic variability can be assessed at a number of different levels; first, intergenotypic variability may arise in genomic regions that are conserved within the same subtype but are distinct between subtypes. Second, there is intragenotypic variability, which may be defined as regions of viral variability within the same genotype or subtype. Finally, intrahost variability is where viral genomic variability occurs within the same viral subtype and also the same host when individual clonal sequences are assessed. Although intergenotypic variability may simply be a feature of the existence of geographically distinct HCV subtypes, intragenotypic and intrahost variability may reflect viral regions subject to specific selection pressures, with important functional implications.We observed two distinct regions of intrahost and intragenotypic hypervariability within genotype 3a envelope 2 (E2)—in addition to the previously described HVR1—that we have named HVR495 and HVR575. We show that these regions are subject to positive selection pressure, sometimes very early in acute infection. Although HVR575 has been previously recognized as a site of intergenotypic variation (18), the identification of this region as a hypervariable site within genotype 3a and as a site under early selection pressure leading to variability within the same host has not been previously described. 相似文献