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91.
Conversion of a high molecular weight latent beta-TGF from chicken embryo fibroblasts into a low molecular weight active beta-TGF under acidic conditions 总被引:40,自引:0,他引:40
D A Lawrence R Pircher P Jullien 《Biochemical and biophysical research communications》1985,133(3):1026-1034
A latent beta-TGF activity is spontaneously released into serum-free culture medium by chicken embryo fibroblasts. Anchorage-independent growth activity measured on NRK-49F indicator cells, of this latent beta-TGF can be revealed by four different treatments: acidification, alkalinisation, exposure to urea, and heating to 100 degrees C for 3 minutes. This lact activating treatment indicates that latent beta-TGF activation in vitro is non-enzymatic. Active beta-TGF exists in a low molecular weight form 16 Kd (apparent) in 1M acetic acid, which elutes on reverse phase (FPLC) between 33-35% acetonitrile. Under neutral conditions only a high molecular weight form excluded on Biogel P60 is observed. This form is poorly active on NRK-49F for anchorage independent growth but can be fully activated by prior acidification. Rechromatography of the latent beta-TGF-containing fractions under acidic conditions converts the high molecular weight form to an apparent 16 Kd active form. We suggest that the high molecular weight form may correspond to a complex of a beta-TGF associated with a carrier or binding protein. 相似文献
92.
Sialylation is a biosynthetic process occurring in the trans compartments
of the Golgi apparatus. Corresponding evidence is based on localization and
biochemical studies of alpha2, 6(N)-sialyltransferase (ST6Gal I) as
previously reported. Here we describe generation and characterization of
polyclonal antibodies to recombinant rat alpha2,3(N)-sialyltransferase
(ST3Gal III) expressed as a soluble enzyme in Sf9 cells or as a
beta-galactosidase-human-ST3Gal III fusion- protein from E.coli ,
respectively. These antibodies were used to localize ST3Gal III by
immunofluorescence in various cell lines and rat kidney tissue sections. In
transiently transfected COS cells the antibodies directed to soluble
sialyltransferase or the sialyltransferase portion of the fusion-protein
only recognized the recombinant antigen retained in the endoplasmic
reticulum. However, an antibody fraction crossreactive with
beta-galactosidase recognized natively expressed ST3Gal III which was found
to be colocalized with beta1, 4-galactosyltransferase in the Golgi
apparatus of several cultured cell lines. Antibodies affinity purified on
the beta- galactosidase-ST3Gal III fusion-protein column derived from both
antisera have then been used to localize the enzyme in perfusion-fixed rat
kidney sections. We found strong staining of the Golgi apparatus of tubular
epithelia and a brush-border-associated staining which colocalized with
cytochemical staining of the H+ATPase. This subcellular localization was
not observed for ST6Gal I which localized to the Golgi apparatus. These
data show colocalization in the Golgi apparatus and different post-Golgi
distributions of the two sialyltransferases.
相似文献
93.
D A Lawrence R Pircher C Krycève-Martinerie P Jullien 《Journal of cellular physiology》1984,121(1):184-188
Normal chicken, mouse, and human embryo fibroblasts release into their culture media transforming growth factors (TGFs) in a latent form. Their soft agar colony-forming activity on two widely used target cells, rat NRK-49F and mouse AKR-2B, is essentially revealed only after prior acidification of cell-conditioned media. These TGFs are EGF-dependent when assayed on NRK-49F cells and EGF-independent on AKR-2B cells. The TGF activity from the chicken source is released in three (apparent) molecular weight forms of 500 kd, 125 kd, and 20 kd. 相似文献
94.
Lymphocyte locomotion and attachment on two-dimensional surfaces and in three-dimensional matrices 总被引:9,自引:3,他引:6
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The adhesion and locomotion of mouse peripheral lymph node lymphocytes on 2-D protein- coated substrata and in 3-D matrices were compared. Lymphocytes did not adhere to, or migrate on, 2-D substrata suck as serum- or fibronectin-coated glass. They did attach to and migrate in hydrated 3-D collagen lattices. When the collagen was dehydrated to form a 2-D surface, lymphocyte attachment to it was reduced. We propose that lymphocytes, which are poorly adhesive, are able to attach to and migrate in 3-D matrices by a nonadhesive mechanism such as the extension and expansion of pseudopodia through gaps in the matrix, which could provide purchase for movement in the absence of discrete intermolecular adhesions. This was supported by studies using serum-coated micropore filters, since lymphocytes attached to and migrated into filters with pore sizes large enough (3 or 8 mum) to allow pseudopod penetration but did not attach to filters made of an identical material (cellulose esters) but of narrow pore size (0.22 or 0.45 mum). Cinematographic studies of lymphocyte locomotion in collagen gels were also consistent with the above hypothesis, since lymphocytes showed a more variable morphology than is typically seen on plane surfaces, with formation of many small pseudopodia expanded to give a marked constriction between the cell and the pseudopod. These extensions often remained fixed with respect to the environment as the lymphocyte moved away from or past them. This suggests that the pseudopodia were inserted into gaps in the gel matrix and acted as anchorage points for locomotion. 相似文献
95.
Haymo Pircher Susanne von Grafenstein Thomas Diener Christina Metzger Eva Albertini Andrea Taferner Hermann Unterluggauer Christian Kramer Klaus R. Liedl Pidder Jansen-Dürr 《The Journal of biological chemistry》2015,290(11):6755-6762
Fumarylacetoacetate hydrolase (FAH) domain-containing proteins occur in both prokaryotes and eukaryotes, where they carry out diverse enzymatic reactions, probably related to structural differences in their respective FAH domains; however, the precise relationship between structure of the FAH domain and the associated enzyme function remains elusive. In mammals, three FAH domain-containing proteins, FAHD1, FAHD2A, and FAHD2B, are known; however, their enzymatic function, if any, remains to be demonstrated. In bacteria, oxaloacetate is subject to enzymatic decarboxylation; however, oxaloacetate decarboxylases (ODx) were so far not identified in eukaryotes. Based on molecular modeling and subsequent biochemical investigations, we identified FAHD1 as a eukaryotic ODx enzyme. The results presented here indicate that dedicated oxaloacetate decarboxylases exist in eukaryotes. 相似文献
96.
Matheus S Gasparini Leandro M dos Santos Ahmad MA Hamade Luísa G Gross Arthur P Favarato Jos PC de Vasconcellos Mnica B de Melo Pierina L Parise Camila L Simeoni Natlia B Silva Marcelo A da Silva Mori Andr S Vieira Alessandro dos Santos Farias Fabiana Granja Angelica Z Schreiber Maria L Moretti Jos L Proena-Modena Mnica Alves 《Experimental biology and medicine (Maywood, N.J.)》2021,246(23):2495
97.
98.
Taferner A Micutkova L Hermann M Jansen-Dürr P Pircher H 《Journal of cell communication and signaling》2011,5(4):277-289
Insulin-like growth factor binding proteins (IGFBPs) are key regulators of insulin-like growth factor (IGF) mediated signal
transduction and thereby can profoundly influence cellular phenotypes and cell fate. Whereas IGFBPs are extracellular proteins,
intracellular activities were described for several IGFBP family members, such as IGFBP-3, which can be reinternalized by
endocytosis and reaches the nucleus through routes that remain to be fully established. Within the family of IGFBPs, IGFBP-6
is unique for its specific binding to IGF-II. IGFBP-6 was described to possess additional IGF-independent activities, which
have in part been attributed to its translocation to the nucleus; however, cellular uptake of IGFBP-6 was not described. To
further explore IGFBP-6 functions, we developed a new method for the purification of native human IGFBP-6 from cell culture
supernatants, involving a four-step affinity purification procedure, which yields highly enriched IGFBP-6. Whereas protein
purified in this way retained the capacity to interact with IGF-II and modulate IGF-dependent signal transduction, our data
suggest that, unlike IGFBP-3, human IGFBP-6 is not readily internalized by human tumor cells. To summarize, this work describes
a novel and efficient method for the purification of native human insulin-like growth factor binding protein 6 (IGFBP-6) from
human cell culture supernatants, applying a four-step chromatography procedure. Intactness of purified IGFBP-6 was confirmed
by IGF ligand Western blot and ability to modulate IGF-dependent signal transduction. Cellular uptake studies were performed
to further characterize the purified protein, showing no short-term uptake of IGFBP-6, in contrast to IGFBP-3. 相似文献
99.
100.
Fabíola C Toledo Juliana E Perobelli Flávia PC Pedrosa Janete A Anselmo-Franci Wilma DG Kempinas 《Reproductive biology and endocrinology : RB&E》2011,9(1):1-9