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101.
Incompatibility of connexin 40 and 43 Hemichannels in gap junctions between mammalian cells is determined by intracellular domains. 总被引:2,自引:0,他引:2 下载免费PDF全文
S Haubrich H J Schwarz F Bukauskas H Lichtenberg-Frat O Traub R Weingart K Willecke 《Molecular biology of the cell》1996,7(12):1995-2006
Murine connexin 40 (Cx40) and connexin 43 (Cx43) do not form functional heterotypic gap junction channels. This property may contribute to the preferential propagation of action potentials in murine conductive myocardium (expressing Cx40) which is surrounded by working myocardium, expressing Cx43. When mouse Cx40 and Cx43 were individually expressed in cocultured human HeLa cells, no punctate immunofluorescent signals were detected on apposed plasma membranes between different transfectants, using antibodies specific for each connexin, suggesting that Cx40 and Cx43 hemichannels do not dock to each other. We wanted to identify domains in these connexin proteins which are responsible for the incompatibility. Thus, we expressed in HeLa cells several chimeric gene constructs in which different extracellular and intracellular domains of Cx43 had been spliced into the corresponding regions of Cx40. We found that exchange of both extracellular loops (E1 and E2) in this system (Cx40*43E1,2) was required for formation of homotypic and heterotypic conductive channels, although the electrical properties differed from those of Cx40 or Cx43 channels. Thus, the extracellular domains of Cx43 can be directed to form functional homo- and heterotypic channels. Another chimeric construct in which both extracellular domains and the central cytoplasmic loop (E1, E2, and C2) of Cx43 were spliced into Cx40 (Cx40*43E1,2,C2) led to heterotypic coupling only with Cx43 and not with Cx40 transfectants. Thus, the central cytoplasmic loop of Cx43 contributed to selectivity. A third construct, in which only the C-terminal domain (C3) of Cx43 was spliced into Cx40, i.e., Cx40*43C3, showed neither homotypic nor heterotypic coupling with Cx40 and Cx43 transfectants, suggesting that the C-terminal region of Cx43 determined incompatibility. 相似文献
102.
103.
Upregulation of gap junction protein connexin43 in alveolar epithelial cells of rats with radiation-induced pulmonary fibrosis 总被引:2,自引:2,他引:0
Michael Kasper Otto Traub Thomas Reimann Leif Bjermer Heinz Großmann Martin Müller Klaus-Wolfgang Wenzel 《Histochemistry and cell biology》1996,106(4):419-424
The degree of immunoreactive connexin43 (Cx43) in rat lung was evaluated during the development of radiation-induced pulmonary
fibrosis in rat by a double immunofluorescence technique using polyclonal antisera to Cx43 and monoclonal antibodies to cytokeratins
on cryostat sections. In normal rat lungs, Cx43 was detected in pneumocytes type II and I, in large blood vessel endothelia,
in peribronchial smooth muscle cells, and in some peribronchial and perivascular interstitial cells. As early as 1 week after
irradiation, enhanced immunoreactivity for Cx43 in the epithelial cells was detected. In severely injured lungs (about 3 months
after irradiation), Cx43 was found also in the cytoplasm of type II pneumocytes. These findings were confirmed by western
blot data. Western blot analysis also revealed increased phosphorylation of Cx43. It remains to be investigated whether the
increased content of Cx43 in irradiated rat lung may be due to an enhanced number of gap junctions between type I and II alveolar
epithelial cells.
Accepted: 20 May 1996 相似文献
104.
The teleost Fundulus heteroclitus (L.) possesses two loci, Gpi-A and Gpi-B,
for the glycolytic enzyme, glucose-phosphate isomerase (GPI; D-
glucose-6-phosphate ketol-isomerase; E.C. 5.3.1.9). The Gpi-B locus is
polymorphic in Fundulus, with two common alleles, Gpi-Bb and Gpi-Bc,
distributed in a clinal manner in populations along the east coast of North
America. Since this clinal distribution is strongly correlated with a
temperature gradient, we asked whether the GPI-B2 allozymes were
functionally adapted to the thermal environment in which a given phenotype
predominated. The two major GPI-B2 allozymes were purified to homogeneity
and were characterized as to molecular weight, isoelectric pH, thermal
denaturation, and kinetic parameters. Both GPI-Bb2 and GPI- Bc2 allozymes
have molecular masses of 110 kD, and they have isoelectric pHs of 6.4 and
6.6, respectively. The GPI-Bb2 allozyme was more stable to thermal
denaturation than was the GPI-Bc2 enzyme. Kinetic properties of the allelic
isozymes were investigated both as a function of pH and as a function of
temperature. At 25 degrees C, over the pH range considered, there were no
significant differences between allozymes, either in Km for
fructose-6-phosphate or in Ki for 6- phosphogluconate, but apparent Vmax
values differed between pH 7.5 and pH 8.5. All steady-state kinetic
parameters showed strong temperature dependence, but the allozymes differed
only in the Ki for 6- phosphogluconate at temperatures greater than 30
degrees C. On the basis of the observed structural and functional
differences alluded to above, the hypothesis that the major allelic
isozymes of the Gpi-B locus were functionally equivalent was rejected.
However, it is not yet known whether these structural and functional
differences have any significance at higher levels of biological
organization.
相似文献
105.
Synaptic contact between dynorphin A(1–8)-like immunoreactive lamina V spinal neurons and calcitonin gene-related peptide-like immunoreactive axon terminals was demonstrated using the immuno-electron microscopic mirror technique in a rat model of peripheral inflammation and hyperalgesia. Adjacent tissue sections were immunocytochemically labeled for either dynorphin A(1–8) or calcitonin gene-related peptide and examined at the electron microscopic level for the presence of synaptic contacts. The results suggest that some opioid neurons which exhibit a dynamic increase in dynorphin peptide associated with peripheral inflammation and hyperalgesia receive direct monosynaptic input from presumptive nociceptive primary afferents. 相似文献
106.
A total of 350 staphylococci isolated from various clinical sources were examined for bound and free coagulase, fermentation of mannitol, and deoxyribonuclease. The economical coagulase-mannitol-agar method of Esber and Faulcomer was found to be suitable for the detection of free coagulase and mannitol fermentation. A significant number of coagulase- and mannitol-negative staphylococci proved to be deoxyribonuclease-positive. 相似文献
107.
During 10 months, 155 isolates of Serratia marcescens were cultured from 105 patients, of whom 49 were considered to have significant infection. The 155 isolates were typed by bacteriocin sensitivity, and 137 (88.4%) were assigned to 37 provisional bacteriocin groups; 18 isolates were nontypable. No major outbreaks of nosocomial infection were demonstrable; however, there were four chronologically separate minor episodes of cross-infection that involved two or three patients per room or unit, respectively. 相似文献
108.
Electrostatic and hydrophobic interactions of the intermediate filament protein vimentin and its amino terminus with lipid bilayers 总被引:7,自引:0,他引:7
Immunofluorescence and electron microscopical studies on the intracellular distribution of intermediate filaments (IFs) have demonstrated a close proximity of these cytoskeletal structures to cellular membranes. Moreover, nonepithelial IF (protein)s have been shown to exhibit high affinities for lipids, especially for negatively charged and nonpolar lipids. Here, using hydrophobic labeling with the photoactivatable phosphatidylcholine analogue [3H]1-palmitoyl-2-[11-[4-(trifluoromethyldiazirinyl]undecanoyl+ ++]-sn- glycero-3-phosphorylcholine or with 1-azidopyrene at low and physiological ionic strength, it is demonstrated that the IF subunit protein vimentin can interact with the hydrophobic core of lipid bilayers, in addition to strong ionic relationships between both reactants. Whereas the presence of acidic phospholipids in the lipid vesicles was absolutely essential for efficient vimentin labeling, cholesterol played a synergistic role in this reaction. Proteolytic degradation of photolabeled vimentin localized the derivatization exclusively to the non-alpha-helical, highly positively charged N-terminal domain of the filament protein. Furthermore, circular dichroism studies performed on the isolated N terminus of vimentin revealed a significant increase in the alpha-helical content of the polypeptide upon its interaction with vesicles containing negatively charged phospholipids. These results indicate an amphiphilic character of the N terminus and suggest that the cationic arginine residues of the N-terminal domain react with the negatively charged head groups of acidic phospholipids prior or parallel to interaction of the polypeptide with hydrophobic regions of the lipid bilayer. 相似文献
109.
W T London A J Martinez S A Houff W C Wallen B L Curfman R G Traub J L Sever 《Teratology》1986,33(3):323-331
Cytomegalovirus (CMV) infections occur worldwide and are responsible for severe damage to the child in from one to five newborns per 20,000 births. Animal models of congenital CMV infection resulting in disease have been developed in mice and guinea pigs. We report here the development of ventricular dilatation and leptomeningitis in rhesus monkeys, Macaca mulatta, following intrauterine infection with rhesus cytomegalovirus (RCMV). Central nervous system (CNS) lesions were associated with low cytomegalovirus fluorescent antibody titers in affected fetuses. In several infected animals, RCMV was isolated at necropsy from neural and nonneural tissues taken shortly after birth. This model allows investigators to study the pathogenesis and prevention of CNS changes following RCMV infection. 相似文献
110.
Summary Large scale production of human lymphoblastoid (Namalva) interferon (IF) is described. Cell propagation, in up to 50 1 culture volume, was carried out in a low cost medium by a semi-continuous cultivation method. IF was induced by Sendai virus, testing two induction methods. The yield of crude IF varied in the range of 12 – 100 × 103 IF units.ml-1. A weekly production output of 1 – 5 × 108 units crude IF was obtained. 相似文献