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1.
R. Brändén T. Nilsson S. Styring 《Biochemical and biophysical research communications》1980,92(4):1297-1305
A sensitive and reliable method to determine the stereochemical composition of 3-phosphoglyceric acid is presented. Results obtained with this method show that 3-phosphoglyceric acid formed in the ribulose-1,5-bisphosphate carboxylase reaction is a mixture of 10% L-3-PGA and 90% D-3-PGA. 相似文献
2.
Previous work from our laboratory (Biochem. J. 219:689–697 (1984) had shown that hydrocortisone stimulated the net accumulation of the myelin-specific sulfolipid in cultures of cells dissociated from embryonic mouse cerebra. This accumulation caused by hydrocortisone was shown to be due to a decrease of sulfolipid degradation by arylsulfatase A (ASA) and not due to a stimulation of its synthesis by a sulfotransferase. Both ASA activity and the turnover of sulfolipid were decreased by hydrocortisone to 60–62% of untreated cells. In current work the same decrease in enzyme activity was obtained and enzyme linked immunosorbent assays demonstrate that hydrocortisone decreased the number of ASA protein molecules to 61% of untreated cells [(-)hydrocorcortisone 0.31±0.06 ng ASA/g protein; (+)hydrocortisone: 0.18±0.04 ng ASA/g protein]. This decrease in the number of ASA molecules correlates well with the decrease in both the enzyme activity and the sulfolipid turnover, which suggests that the major mode of inhibition of ASA activity by hydrocortisone involves a decrease in the concentration of ASA in the cells rather than some other mechanism of inhibition.The material in this paper has been included in a dissertation submitted by A.J.M. in partial fulfillment of the requirements for the degree of Doctor of Philosophy. Temple University. 相似文献
3.
A. C. Passaquin G. Coupin W. A. Schreier P. Poindron R. A. Cole J. de Vellis 《Neurochemical research》1989,14(10):987-993
We investigated the effect of rat interferon-/ (IFN) on the expression of glycerol phosphate dehydrogenase (E.C.1.1.1.8; GPDH), in both C6 cells and pure cultures of oligodendrocytes. IFNs are naturally produced inhibitors of cell growth that can also affect differentiated cell functions. GPDH is a biochemical marker for oligodendrocytes and is known to be developmentally regulated and steroid inducible. GPDH activity is induced by hydrocortisone (HC) 3.5 fold in C6 cells and 5 fold in oligodendrocytes compared to untreated cultures. A pretreatment of these cells with 75 U/ml of rat IFN-/ resulted in an inhibition of the HC induction of GPDH enzymatic activity by 50% and 40% in C6 cells and oligodendrocytes respectively. We also found that IFN impaired the accumulation of GPDH mRNA in both cell types. These results demonstrate that IFNs are capable of modifying the cellular response to hormones in cells of neuroepithelial origin, and suggest the possibility that IFNs may be able to influence the development and function of the brain.Special issue dedicated to Dr. Paola S. Timiras 相似文献
4.
5.
Fibroblast heterogeneity in glucocorticoid regulation of collagen metabolism: Genetic or epigenetic?
James D. Russell Shirley B. Russell Kathryn M. Trupin 《In vitro cellular & developmental biology. Plant》1982,18(6):557-564
Summary Cultured fibroblasts derived from normal human dermis show a consistent 62% inhibition of collagen synthesis by hydrocortisone,
whereas cultures derived from keloids average only 30% inhibition and show a much larger strain to strain variation ranging
from 75% inhibition to 49% stimulation. Examination of fibroblast clones indicates that this high variation among keloid strains
is not due to differences in the proportion of normal and keloid cells in the mass culture populations. Small but significant
differences in the effect of hydrocortisone on collagen deposition are also seen among these clonal populations, but are not
related to the type of tissue from which cultures were derived. Two to three-fold differences among clones derived from a
single individual were observed, possibly suggesting functional heterogeneity of dermal fibroblasts with regard to collagen
metabolism under control conditions and in response to hydrocortisone. However, this variation among clones may simply reflect
differences in clonal growth, inasmuch as both collagen synthesis and deposition, and the effect of hydrocortisone on these
processes, are strongly affected by population density.
This work was supported in part by PHS grants, CA-17229 from the National Cancer Institute and AG-02046 from the National
Institute on Aging, DHHS; and by Grant RIM 78-17313 from the National Science Foundation. 相似文献
6.
Demonstration of growth in porcine thyroid cell culture 总被引:2,自引:0,他引:2
Eagle's minimum essential medium supplemented with 20 per cent newborn calf serum (N.C.S.) allows porcine thyroid cell survival but not cell growth in vitro. In NCTC 109 medium supplemented with 20 per cent N.C.S. these cells actively grow and may be serially propagated. Cell population doubling time expressed as DNA doubling value is 3.5 days at 37 degrees C in 95 per cent air-5 per cent CO2. Thyrotropin does not affect porcine thyroid cell multiplication in vitro but stimulates the plating efficiency in primary cultures to about 130 per cent of controls. Cell selection was obtained by replacing media with Earle's balanced salt solution. This operation provoked death of nearly all cells by day 18 but subsequent addition of growth medium resulted in proliferation of epithelial cell clones. From generation 2 to generation 8, cells produce thyroglobulin but they do not actively trap iodide nor form follicles when thyrotropin is added to the media. Cell selection, demonstration of growth, as well as freeze-storage techniques described in this paper permit selection and storage of porcine thyroid cells and the potential constitution of cell collections. 相似文献
7.
Su-Chin C. Liu Mary J. Eaton Marvin A. Karasek 《In vitro cellular & developmental biology. Plant》1979,15(10):813-822
Summary Using gels of acid-soluble, collagen as a culture surface, trypsin-released keartinocytes from 0.1-mm, split-thickness sections
of newborn foreskin may be plated with high efficiency and subcultured at a 1∶5 split a 2- to 3-week intervals for three subpassages.
When plated at a density of 3.2×104 cells per cm2, keratinocytes attach to the gel with an efficiency of over 70%; after a lag phase of 3 days, the cells multiply exponentially
with a doubling time of 60 hr. Cultures reach a growth-plateau phase at a density of 47.7×104 cells per cm2. Both hydrocortisone and epidermal growth factor (EGF) stimulate slightly the growth of primary cultures; both factors are
required for proliferation of the 2nd and further passage of keratinocytes. As the cultures reach, confluence multilayers,
of stratified cells are formed and cells of squamous morphology are spontaneously released from the surface. When the released
cells and the attached cells are pulsed with [3H]-histidine and [14C]-leucine, a higher ratio of histidine to leucine is observed in the released cells indicating the biochemical onset of maturation.
Orange G-Aniline Blue staining of the released cells show some of the cells to be completely keratinized. Fibrous proteins
extracted from the cultured cells and analyzed by sodium dodecyl sulfate (SDS) gel electrophoresis display the characteristic
stratum corneum proteins of 60,000 and 66,000 daltons.
Supported in part by Grants AM 14121 and AM 19595 of the U.S. Public Health Service. 相似文献
8.
9.
Thymocyte adhesion to thymic epithelial cells is a relevant issue during intrathymic T-cell differentiation, and directly intervenes in the generation and expansion of the T-cell repertoire. In view of these data, it was apparent the usefulness of an automated strategy to evaluate the degree of thymic epithelial cell-thymocyte adhesion. This prompted us to develop an ELISA procedure (using an anti-Thy1 reagent) to determine the degree of thymocyte adhesion onto cultured thymic epithelial cells. The procedure described herein is simple, non-radioactive and reproducible. Additionally, it can potentially be applied to quantitate the degree of thymocyte adhesion to any cellular or non-cellular substrate (for example, extracellular matrix). Moreover, it detected fluctuations of thymocyte adhesion secondary to glucocorticoid treatment of epithelial cells. Thus, it can be regarded as a further tool to analyze intrathymic interactions. 相似文献
10.
Previous studies have shown a role for multiple drug resistance proteins in protecting the fetus from a limited number of teratogens. We have expanded the number of proteins and teratogens examined by comparing the influence of the mdr1a and mdr2 proteins on teratogen-induced orofacial clefting using their respective knockouts in crosses with the A/J, high susceptibility strain. Western blots identified the presence of mdr1a and possibly mdr2 in the placenta and fetus. The mdr1a knockout, on its unique genetic background showed lower, similar, and higher incidences of clefting compared to A/J for Dilantin, hydrocortisone (HC), and 6-aminonicotinamide (6-AN), respectively. The mdr2 knockout did not affect 6-AN clefting when compared to A/J. In reciprocal crosses, when corrected for increased spontaneous clefting, maternally inherited A/J susceptibility genes predominated over the effects of the maternal absence of mdr1a (with 6-AN). Unlike mdr1a, which had a direct effect in the fetus as shown by genotyping of affected versus unaffected fetuses, an effect of mdr2 in the fetus was not found. The mdr1a knockout was backcrossed to the A/J inbred strain for 11 generations (congenics) to eliminate genetic background effects. Reciprocal crosses showed no maternal effect from the lack of mdr1a, confirming that mdr1a expression in the fetus, rather than the placenta, protects the fetus from teratogens. Mdr2 seems not to be involved in the protection of the fetus from teratogens. 相似文献