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71.
Grippo AJ Santos CM Johnson RF Beltz TG Martins JB Felder RB Johnson AK 《American journal of physiology. Heart and circulatory physiology》2004,286(2):H619-H626
Depression is an important public health problem and is considered to be an independent risk factor for coronary artery disease. The pathophysiological mechanisms that link depression with adverse cardiovascular events (e.g., myocardial ischemia, myocardial infarction, and sudden death) are not well established. It is possible that an increased susceptibility to life-threatening cardiac arrhythmias in depressed patients influences the risk of morbidity and mortality in coronary artery disease. This idea was tested with the use of an experimental model of depression that was developed to induce anhedonia, the reduced responsiveness to pleasurable stimuli observed in human depressed patients. Rats exposed to 4 wk of chronic mild stress (e.g., paired housing, strobe light, and white noise) displayed anhedonia, which was operationally defined by the reduced intake of a palatable sucrose solution relative to an established baseline and to control animals. Furthermore, compared with control rats, the anhedonic rats showed increased basal heart rate and decreased heart rate variability. In response to an intravenously infused chemical challenge, aconitine, anhedonic rats exhibited an increased vulnerability to ventricular arrhythmias, as indicated by a reduced threshold for premature ventricular complexes, salvos, and ventricular tachycardia. These findings suggest that the presence of depressive symptoms is associated with a lower threshold for ventricular arrhythmias, which may contribute to the increased risk for adverse cardiovascular events in patients with depression. 相似文献
72.
Phylogenetic relationships within the Alcidae (Charadriiformes: Aves) inferred from total molecular evidence 总被引:4,自引:1,他引:3
The Alcidae is a unique assemblage of Northern Hemisphere seabirds that
forage by "flying" underwater. Despite obvious affinities among the
species, their evolutionary relationships are unclear. We analyzed
nucleotide sequences of 1,045 base pairs of the mitochondrial cytochrome b
gene and allelic profiles for 37 allozyme loci in all 22 extant species.
Trees were constructed on independent and combined data sets using maximum
parsimony and distance methods that correct for superimposed changes.
Alternative methods of analysis produced only minor differences in
relationships that were supported strongly by bootstrapping or standard
error tests. Combining sequence and allozyme data into a single analysis
provided the greatest number of relationships receiving strong support.
Addition of published morphological and ecological data did not improve
support for any additional relationship. All analyses grouped species into
six distinct lineages: (1) the dovekie (Alle alle) and auks, (2)
guillemots, (3) brachyramphine murrelets, (4) synthliboramphine murrelets,
(5) true auklets, and (6) the rhinoceros auklet (Cerorhinca monocerata) and
puffins. The two murres (genus Uria) were sister taxa, and the black
guillemot (Cepphus grylle) was basal to the other guillemots. The Asian
subspecies of the marbled murrelet (Brachyramphus marmoratus perdix) was
the most divergent brachyramphine murrelet, and two distinct lineages
occurred within the synthliboramphine murrelets. Cassin's auklet
(Ptychoramphus aleuticus) and the rhinoceros auklet were basal to the other
auklets and puffins, respectively, and the Atlantic (Fratercula arctica)
and horned (Fratercula corniculata) puffins were sister taxa. Several
relationships among tribes, among the dovekie and auks, and among the
auklets could not be resolved but resembled "star" phylogenies indicative
of adaptive radiations at different depths within the trees.
相似文献
73.
By utilization of polymerase chain reaction techniques, single-stranded DNA of defined length and sequence containing a purine analog, 2-chloroadenine, in place of adenine was synthesized. This was accomplished by a combination of standard polymerase chain amplification reactions with Thermus aquaticus DNA polymerase in the presence of four normal deoxynucleoside triphosphates, M13 duplex DNA as template, and two primers to generate double-stranded DNA 118 bases in length. An asymmetric polymerase chain reaction, which produced an excess of single-stranded 98-base DNA, was then conducted with 2-chloro-2'-deoxy-adenosine 5'-triphosphate in place of dATP and with only one primer that annealed internal to the original two primers. Standard polymerase chain reaction techniques alone conducted in the presence of the analog as the fourth nucleotide did not produce duplex DNA that was modified within both strands. This asymmetric technique allows the incorporation of an altered nucleotide at specific sites into large quantities of single-stranded DNA without using chemical phosphoramidite synthesis procedures and circumvents the apparent inability of DNA polymerase to synthesize fully substituted double-stranded DNA during standard amplification reactions. The described method will permit the study of the effects of modified bases in template DNA on a variety of protein-DNA interactions and enzymes. 相似文献
74.
75.
76.
G. Tholey M. Ledig P. Mandel L. Sargentini A. H. Frivold M. Leroy A. A. Grippo Dr. F. C. Wedler 《Neurochemical research》1988,13(1):45-50
Energy dispersive x-ray fluorescence and atomic absorption spectroscopy were used to determine the concentrations of Mg, Ca, Mn, Fe, Zn, and Cu in primary cultures of astroglial cells from chick embryo cortex in chemically defined serum-free growth medium. The intracellular volume of cultured glia was determined to be 8.34 l/mg protein. Intracellular Mn, Fe, Zn, and Cu in these cells were ca. 10–200 M, or 20–200 times the concentrations in the growth medium. Mg2+ was 7 mM in glial cells, only four-fold higher than in growth medium. Glutamine synthetase (GS), compartmentalized in glia, catalyzes a key step in the metabolism of neurotransmitterl-glutamate as part of the glutamate/glutamine cycle between neurons and glia. Hormones (insulin, hydrocortisone, and cAMP) added to growth medium differentially altered the activity of GS and the intracellular level of Mn(II), but not Mg(II). These findings suggest the possibility that glutamine synthetase activity could be regulated in brain by the intracellular levels of Mn(II) or the ratio of Mn(II)/Mg(II), which may in turn be controlled indirectly by means of transport processes that respond to hormones or secondary metabolic signals. 相似文献
77.
Katherine N Choe Claudia M Nicolae Daniel Constantin Yuka Imamura Kawasawa Maria Rocio Delgado‐Diaz Subhajyoti De Raimundo Freire Veronique AJ Smits George‐Lucian Moldovan 《EMBO reports》2016,17(6):874-886
Defects in DNA replication, DNA damage response, and DNA repair compromise genomic stability and promote cancer development. In particular, unrepaired DNA lesions can arrest the progression of the DNA replication machinery during S‐phase, causing replication stress, mutations, and DNA breaks. HUWE1 is a HECT‐type ubiquitin ligase that targets proteins involved in cell fate, survival, and differentiation. Here, we report that HUWE1 is essential for genomic stability, by promoting replication of damaged DNA. We show that HUWE1‐knockout cells are unable to mitigate replication stress, resulting in replication defects and DNA breakage. Importantly, we find that this novel role of HUWE1 requires its interaction with the replication factor PCNA, a master regulator of replication fork restart, at stalled replication forks. Finally, we provide evidence that HUWE1 mono‐ubiquitinates H2AX to promote signaling at stalled forks. Altogether, our work identifies HUWE1 as a novel regulator of the replication stress response. 相似文献
78.
Jurriaan J Hölzenspies Willem Stoorvogel Ben Colenbrander Bernard AJ Roelen Dagmar R Gutknecht Theo van Haeften 《BMC developmental biology》2009,9(1):1-16
Background
Fibronectin 1 (FN1), a glycoprotein component of the extracellular matrix, exerts different functions during reproductive processes such as fertilisation, gastrulation and implantation. FN1 expression has been described to increase significantly from the morula towards the early blastocyst stage, suggesting that FN1 may also be involved in early blastocyst formation. By alternative splicing at 3 defined regions, different FN1 isoforms are generated, each with a unique biological function. The analysis of the alternative FN1 splicing on the one hand and the search for candidate FN1 receptors on the other hand during early bovine embryo development may reveal more about its function during bovine preimplantation embryo development. 相似文献79.
Tania Maes Sharen Provoost Ellen A Lanckacker Didier D Cataldo Jeroen AJ Vanoirbeek Benoit Nemery Kurt G Tournoy Guy F Joos 《Respiratory research》2010,11(1):1-16
Background
Nicotinic acetylcholine receptors (nAChR) have been identified on a variety of cells of the immune system and are generally considered to trigger anti-inflammatory events. In the present study, we determine the nAChR inventory of rat alveolar macrophages (AM), and investigate the cellular events evoked by stimulation with nicotine.Methods
Rat AM were isolated freshly by bronchoalveolar lavage. The expression of nAChR subunits was analyzed by RT-PCR, immunohistochemistry, and Western blotting. To evaluate function of nAChR subunits, electrophysiological recordings and measurements of intracellular calcium concentration ([Ca2+]i) were conducted.Results
Positive RT-PCR results were obtained for nAChR subunits α3, α5, α9, α10, β1, and β2, with most stable expression being noted for subunits α9, α10, β1, and β2. Notably, mRNA coding for subunit α7 which is proposed to convey the nicotinic anti-inflammatory response of macrophages from other sources than the lung was not detected. RT-PCR data were supported by immunohistochemistry on AM isolated by lavage, as well as in lung tissue sections and by Western blotting. Neither whole-cell patch clamp recordings nor measurements of [Ca2+]i revealed changes in membrane current in response to ACh and in [Ca2+]i in response to nicotine, respectively. However, nicotine (100 μM), given 2 min prior to ATP, significantly reduced the ATP-induced rise in [Ca2+]i by 30%. This effect was blocked by α-bungarotoxin and did not depend on the presence of extracellular calcium.Conclusions
Rat AM are equipped with modulatory nAChR with properties distinct from ionotropic nAChR mediating synaptic transmission in the nervous system. Their stimulation with nicotine dampens ATP-induced Ca2+-release from intracellular stores. Thus, the present study identifies the first acute receptor-mediated nicotinic effect on AM with anti-inflammatory potential. 相似文献80.
Andreas Stein Martina Knödler Markus Makowski Sandra Kühnel Stefan Nekolla Alexandra Keithahn Eliane Weidl Philip Groha Maren Schürmann Atti Saraste Rene Botnar Robert AJ Oostendorp Ilka Ott 《BMC cardiovascular disorders》2010,10(1):43