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91.
Richard S. Kent Barbara B. Kitchell David G. Shand A.Richard Whorton 《Prostaglandins & other lipid mediators》1981,21(3):483-490
The ability of aortae from young and mature swine to produce prostacyclin (PGI2) has been determined. PGI2 was measured as its hydration product, 6-keto-PGF1α and assayed by stable isotope dilution GC-MS. There was no significant difference in 6-keto-PGF1α production between intimal strips from young and mature aortae in the basal state. In the presence of saturating concentrations of arachidonic acid, however, intimal strips from young aortae synthesized twice as much 6-keto-PGF1α as did older tissues. Fatty acid compositions of young and mature aortae were virtually identical, making dietary differences an unlikely explanation for the age-related decrease in PGI2 synthesis. Both young and mature vascular tissues produced essentially only PGI2; insignificant amounts of PGE2 and PGF2α were found. 相似文献
92.
Prostaglandin (PG) I2 and PGE2 were infused into the aortic arch, femoral vein, renal artery and portal vein in anesthetized dogs over a dose range to produce a steady decrease in systemic blood pressure after 10 mins infusion. Parallel log dose-response relationships were observed with both PGI2 and PGE2. PGE2 was a more potent depressor than PGI2 when infused into the aortic arch. The doses to reduce blood pressure by 5 mm Hg were used to calculate the extraction of the compounds by the lungs, kidney and liver. The pulmonary extraction of PGE2 was 96 ± 2% and was essentially complete following combined pulmonary and renal or pulmonary and hepatic extraction. In contrast, there was no significant pulmonary extraction of PGI2. Combined renal and pulmonary extraction was 43 ± 11% and combined hepatic and pulmonary extraction 87 ± 5%. These results indicate a marked difference in the organ metabolising capacity for PGE2 and PGI2. Since PGI2 has been shown to be produced both in the kidney and stomach it is possible that PGI2 produced endogenously could pass into the circulation and exert systemic pharmacological effects. 相似文献
93.
John F. Gerkens John G. Gerber David G. Shand Robert A. Branch 《Prostaglandins & other lipid mediators》1978,16(5):815-823
Prostaglandins (PG)I2, PGE2 and 6-keto PGF1α were infused directly into the gastric arterial supply at 10−9, 10−8 and 10−7 g/kg/min during an intra-gastric artery pentagastrin infusion in anesthetized dogs. 6-keto PGF1α was also infused at 10−6 g/kg/min. Gastric arterial blood flow was measured continuously with a non-cannulating electromagnetic flow probe and gastric acid collected directly from the stomach. PGI2 and PGE2 produced similar dose-dependent increases in blood flow with an increase of more than four-fold at the highest dose. Both PGs inhibited acid output over this dose range with PGE2 having 10 times the potency of PGI2. 6-keto PGF1α was at least 1000 times less active than PGI2 or PGE2 at increasing blood flow and failed to inhibit acid output even at 10−6 g/kg/min. 相似文献
94.
Studies on the mechanism for entry of vesicular stomatitis virus glycoprotein g mRNA into membrane-bound polyribosome complexes
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Glycoprotein mRNA (G mRNA) of vesicular stomatitis virus is synthesized in the cytosol fraction of infected HeLa cells. Shortly after synthesis, this mRNA associates with 40S ribosomal subunits and subsequently forms 80S monosomes in the cytosol fraction. The bulk of labeled G mRNA is then found in polysomes associated with the membrane, without first appearing in the subunit or monomer pool of the membrane-bound fraction. Inhibition of the initiation of protein synthesis by pactamycin or muconomycin A blocks entry of newly synthesized G m RNA into membrane-bound polysomes. Under these circumstances, labeled G mRNA accumulates into the cytosol. Inhibition of the elongation of protein synthesis by cucloheximide, however, allows entry of 60 percent of newly synthesized G mRNA into membrane-bound polysomes. Furthermore, prelabeled G mRNA associated with membrane-bound polysomes is released from the membrane fraction in vivo by pactamycin or mucomycon A and in vitro by 1mM puromycin - 0.5 M KCI. This release is not due to nonspecific effects of the drugs. These results demonstrate that association of G mRNA with membrane-bound polysomes is dependent upon polysome formation and initiation of protein synthesis. Therefore, direct association of the 3' end of G mRNA with the membrane does not appear to be the initial event in the formation of membrane-bound polysomes. 相似文献
95.
Background
Irreversible airflow obstruction in Chronic Obstructive Pulmonary Disease (COPD) is thought to result from airway remodelling associated with aberrant inflammation. Patients who experience frequent episodes of acute deterioration in symptoms and lung function, termed exacerbations, experience a faster decline in their lung function, and thus over time greater disease severity However the mechanisms by which these episodes may contribute to decreased lung function are poorly understood.This study has prospectively examined changes in sputum levels of inflammatory cells, MMP-9 and TIMP-1 during exacerbations comparing with paired samples taken prior to exacerbation.Methods
Nineteen COPD patients ((median, [IQR]) age 69 [63 to 74], forced expiratory volume in one second (FEV1) 1.0 [0.9 to1.2], FEV1% predicted 37.6 [27.3 to 46.2]) provided sputa at exacerbation. Of these, 12 were paired with a samples collected when the patient was stable, a median 4 months [2 to 8 months] beforehand.Results
MMP-9 levels increased from 10.5 μg/g [1.2 to 21.1] prior to exacerbation to 17.1 μg/g [9.3 to 48.7] during exacerbation (P < 0.01). TIMP-1 levels decreased from 3.5 μg/g [0.6 to 7.8] to 1.5 μg/g [0.3 to 4.9] (P = 0.16). MMP-9/TIMP-1 Molar ratio significantly increased from 0.6 [0.2 to 1.1] to 3.6 [2.0 to 25.3] (P < 0.05). Neutrophil, eosinophil and lymphocyte counts all showed significant increase during exacerbation compared to before (P < 0.05). Macrophage numbers remained level. MMP-9 levels during exacerbation showed highly significant correlation with both neutrophil and lymphocyte counts (Rho = 0.7, P < 0.01).Conclusion
During exacerbation, increased inflammatory burden coincides with an imbalance of the proteinase MMP-9 and its cognate inhibitor TIMP-1. This may suggest a pathway connecting frequent exacerbations with lung function decline. 相似文献96.
TE Willnow C Antignac AW Br?ndli EI Christensen RD Cox D Davidson JA Davies O Devuyst G Eichele ND Hastie PJ Verroust A Schedl IC Meij 《Organogenesis》2005,2(2):42-47
Rapid progress in genome research creates a wealth of information on the functional annotation of mammalian genome sequences. However, as we accumulate large amounts of scientific information we are facing problems of how to integrate and relate the data produced by various genomic approaches. Here, we propose the novel concept of an organ atlas where diverse data from expression maps to histological findings to mutant phenotypes can be queried, compared and visualized in the context of a three-dimensional reconstruction of the organ. We will seek proof of concept for the organ atlas by elucidating genetic pathways involved in development and pathophysiology of the kidney. Such a kidney atlas may provide a paradigm for a new systems-biology approach in functional genome research aimed at understanding the genetic bases of organ development, physiology and disease.Key Words: EuReGene, kidney, genome, development, pathophysiology, genetics 相似文献
97.
In order to reconstruct phylogenetic trees from extremely dissimilar
sequences it is necessary to estimate accurately the extent of sequence
divergence. In this paper a new method of sequence analysis, Markov triple
analysis, is developed for determining the relative frequencies of
nucleotide substitutions within the three branches of a three-taxon
dendrogram. Assuming that nucleotide sites are independently and
identically distributed and assuming a Markov model for nucleotide (or
protein) evolution, it is shown that the unique Markov matrices can be
reconstructed given only the joint probability distribution relating three
taxa. (In the much simpler case involving only two taxa and two character
states, Markov matrices can also be reconstructed, provided symmetry
assumptions are placed on the elements of the matrices.) The method is
illustrated using sequence data from the combined first and second codon
positions derived from complete human, mouse, and cow mitochondrial
sequences.
相似文献
98.
DNA hybridization evidence for the principal lineages of hummingbirds (Aves:Trochilidae) 总被引:3,自引:0,他引:3
The spectacular evolutionary radiation of hummingbirds (Trochilidae) has
served as a model system for many biological studies. To begin to provide a
historical context for these investigations, we generated a complete matrix
of DNA hybridization distances among 26 hummingbirds and an outgroup swift
(Chaetura pelagica) to determine the principal hummingbird lineages. FITCH
topologies estimated from symmetrized delta TmH-C values and subjected to
various validation methods (bootstrapping, weighted jackknifing, branch
length significance) indicated a fundamental split between hermit
(Eutoxeres aquila, Threnetes ruckeri; Phaethornithinae) and nonhermit
(Trochilinae) hummingbirds, and provided strong support for six principal
nonhermit clades with the following branching order: (1) a predominantly
lowland group comprising caribs (Eulampis holosericeus) and relatives
(Androdon aequatorialis and Heliothryx barroti) with violet-ears (Colibri
coruscans) and relatives (Doryfera ludovicae); (2) an Andean-associated
clade of highly polytypic taxa (Eriocnemis, Heliodoxa, and Coeligena); (3)
a second endemic Andean clade (Oreotrochilus chimborazo, Aglaiocercus
coelestis, and Lesbia victoriae) paired with thorntails (Popelairia
conversii); (4) emeralds and relatives (Chlorostilbon mellisugus, Amazilia
tzacatl, Thalurania colombica, Orthorhyncus cristatus and Campylopterus
villaviscensio); (5) mountain-gems (Lampornis clemenciae and Eugenes
fulgens); and (6) tiny bee-like forms (Archilochus colubris, Myrtis fanny,
Acestrura mulsant, and Philodice mitchellii). Corresponding analyses on a
matrix of unsymmetrized delta values gave similar support for these
relationships except that the branching order of the two Andean clades (2,
3 above) was unresolved. In general, subsidiary relationships were
consistent and well supported by both matrices, sometimes revealing
surprising associations between forms that differ dramatically in plumage
and bill morphology. Our results also reveal some basic aspects of
hummingbird ecologic and morphologic evolution. For example, most of the
diverse endemic Andean assemblage apparently comprises two genetically
divergent clades, whereas the majority of North American hummingbirds
belong a single third clade. Genetic distances separating some
morphologically distinct genera (Oreotrochilus, Aglaiocercus, Lesbia;
Myrtis, Acestrura, Philodice) were no greater than among congeneric
(Coeligena) species, indicating that, in hummingbirds, morphological
divergence does not necessarily reflect level of genetic divergence.
相似文献
99.
100.