全文获取类型
收费全文 | 250篇 |
免费 | 27篇 |
出版年
2023年 | 3篇 |
2022年 | 1篇 |
2021年 | 1篇 |
2018年 | 1篇 |
2017年 | 1篇 |
2015年 | 2篇 |
2014年 | 7篇 |
2013年 | 3篇 |
2012年 | 19篇 |
2011年 | 14篇 |
2010年 | 5篇 |
2009年 | 5篇 |
2008年 | 12篇 |
2007年 | 25篇 |
2006年 | 23篇 |
2005年 | 20篇 |
2004年 | 28篇 |
2003年 | 27篇 |
2002年 | 30篇 |
2001年 | 3篇 |
2000年 | 4篇 |
1999年 | 4篇 |
1997年 | 2篇 |
1996年 | 5篇 |
1995年 | 1篇 |
1993年 | 1篇 |
1992年 | 3篇 |
1991年 | 1篇 |
1990年 | 3篇 |
1989年 | 3篇 |
1988年 | 2篇 |
1987年 | 3篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1982年 | 3篇 |
1980年 | 1篇 |
1978年 | 1篇 |
1977年 | 3篇 |
1975年 | 1篇 |
排序方式: 共有277条查询结果,搜索用时 31 毫秒
1.
Structure and function of extracellular matrix proteoglycans 总被引:1,自引:0,他引:1
2.
Identification of a bone sialoprotein receptor in osteosarcoma cells 总被引:12,自引:0,他引:12
A Oldberg A Franzén D Heineg?rd M Pierschbacher E Ruoslahti 《The Journal of biological chemistry》1988,263(36):19433-19436
Bone sialoprotein (BSP) is an extracellular matrix glycoprotein associated with the mineral bone matrix. The amino acid sequence of BSP contains an Arg-Gly-Asp (RGD) sequence which confers to the protein cell binding properties (Oldberg, A., Franzén, A., and Heineg?rd, D. (1988) J. Biol. Chem. 263, 19430-19432). When BSP was used as an affinity matrix to isolate a cell surface receptor from rat osteosarcoma cells, a protein composed of polypeptides similar in size to those of a previously characterized vitronectin receptor was obtained. This putative BSP receptor, like the vitronectin receptor, bound also to an affinity matrix made of an RGD-containing heptapeptide. Moreover, similar patterns of inhibition of cell attachment to BSP and vitronectin was obtained with variant RGD-containing peptides, with BSP and with vitronectin. Finally, an anti-vitronectin receptor antiserum immunoprecipitated a receptor identical in size to the receptor bound to a BSP affinity matrix. These results show that BSP is recognized by an RGD-directed receptor and that both vitronectin and BSP can bind to this receptor. 相似文献
3.
Chondroitin/dermatan sulfate proteoglycan in human fetal membranes. Demonstration of an antigenically similar proteoglycan in fibroblasts 总被引:13,自引:0,他引:13
M J Brennan A Oldberg M D Pierschbacher E Ruoslahti 《The Journal of biological chemistry》1984,259(22):13742-13750
A proteoglycan was isolated from fetal membranes which had been separated from human postpartum placenta. The glycosaminoglycan side chains (Mr = 55,000) were found to be composed of 75% chondroitin sulfate and 23% dermatan sulfate as determined by chondroitinase ABC or AC II digestion. NH2-terminal microsequencing of the intact proteoglycan revealed a single amino acid sequence of (sequence; see text) A rabbit antiserum raised against the intact proteoglycan reacted in sodium dodecyl sulfate-polyacrylamide gel electrophoresis immunoblotting with Mr = 45,000 and 43,000 core polypeptides from chondroitinase-treated proteoglycan. Affinity-purified antibodies from this antiserum precipitated from human embryonic fibroblast culture fluid a proteoglycan which has an approximate Mr = 120,000 in sodium dodecyl sulfate-polyacrylamide gel electrophoresis. This proteoglycan has on the average two polysaccharide side chains. As defined by chondroitinase digestion, these chains consist of 66% dermatan sulfate and 20% chondroitin sulfate. Digestion of the glycosaminoglycan with chondroitinase ABC converted the proteoglycan to a Mr = 45,000 major and a Mr = 43,000 minor core polypeptide. Tissue immunofluorescence localized the proteoglycan to interstitial matrices, suggesting that it is a product of mesenchymal cells. The methods we have devised for the purification of the fetal membrane proteoglycan in chemical amounts and the antibodies we have prepared against it will allow studies on the structural and functional properties of the proteoglycan and on the expression of immunologically cross-reactive proteoglycans by various cells and tissues. 相似文献
4.
The expression and core protein structure of two proteoglycans, the major cartilage proteoglycan isolated from a rat chondrosarcoma and a small molecular weight chondroitin sulfate proteoglycan isolated from a rat yolk sac tumor, have been compared. The cartilage proteoglycan was not detectable in the cartilage tissue of cartilage matrix deficient () neonatal mice by immunofluorescence, but the cmd cartilage did react with antibodies against the core protein of the yolk sac tumor proteoglycan. Radioimmunoassays showed that the core proteins of these proteoglycans are not cross-reactive with each other. Analysis of the core proteins by sodium dodecyl sulfate/polyacrylamide gel electrophoresis after chondroitinase ABC treatment of the proteoglycan revealed a large difference in their sizes. The cartilage proteoglycan core protein had a molecular weight of about 200,000 while the yolk sac tumor proteoglycan core protein migrated with an apparent molecular weight of about 20,000. In addition, the cultured yolk sac tumor cells that make the small proteoglycan did not react with antiserum against the cartilage proteoglycan. These results indicate that the proteoglycan isolated from the yolk sac tumor is similar to the small chondroitin sulfate proteoglycan species found in cartilage and support the existence of at least two dissimilar and genetically independent chondroitin sulfate proteoglycan core proteins. 相似文献
5.
Min Lu Per- Ake Albertsson G te Johansson Folke Tjerneld 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》1996,680(1-2):65-70
Benzoyl dextran with a degree of substitution of 0.18 was synthesized by reacting dextran T500 with benzoyl chloride. A new type of aqueous two-phase system composed of benzoyl dextran as bottom phase polymer and the random copolymer of ethylene oxide and propylene oxide (Ucon 50-HB-5100) as top phase polymer has been formed. The phase diagram for the system Ucon 50-HB-5100-benzoyl dextran with a degree of substitution of 0.18 was determined at room temperature. This two-phase system has been used to purify 3-phosphoglycerate kinase from bakers' yeast. The top-phase polymer (Ucon) can be separated from target enzyme by increasing the temperature. The bottom-phase polymer (benzyol dextran) could be recovered by addition of salt. Yeast homogenate was partitioned in a primary Ucon 50-HB-5100-benzoyl dextran aqueous two-phase system. After phase separation the top phase was removed and temperature-induced phase separation was used for formation of a water phase and a Ucon-rich phase. The benzoyl dextran-enriched bottom phase from the primary system was diluted, and the polymer was separated from water by addition of Na2SO4. 相似文献
6.
Codistribution of heparan sulfate proteoglycan, laminin, and fibronectin in the extracellular matrix of normal rat kidney cells and their coordinate absence in transformed cells 总被引:21,自引:11,他引:10
下载免费PDF全文
![点击此处可从《The Journal of cell biology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
We used antibodies raised against both a heparan sulfate proteoglycan purified from a mouse sarcoma and a chondroitin sulfate proteoglycan purified from a rat yolk sac carcinoma to study the appearance and distribution of proteoglycans in cultured cells. Normal rat kidney cells displayed a fibrillar network of immunoreactive material at the cell surface when stained with antibodies to heparan sulfate proteoglycan, while virally transformed rat kidney cells lacked such a surface network. Antibodies to chondroitin sulfate proteoglycan revealed a punctate pattern on the surface of both cell types. The distribution of these two proteoglycans was compared to that of fibronectin by double-labeling immunofluorescent staining. The heparan sulfate proteoglycan was found to codistribute with fibronectin, and fibronectin and laminin gave coincidental stainings. The distribution of chondroitin sulfate proteoglycan was not coincidental with that of fibronectin. Distinct fibers containing fibronectin but lacking chondroitin sulfate proteoglycan were observed. When the transformed cells were cultured in the presence of sodium butyrate, their morphology changed, and fibronectin, laminin, and heparan sulfate proteoglycan appeared at the cell surface in a pattern resembling that of normal cells. These results suggest that fibronectin, laminin, and heparan sulfate proteoglycan may be complexed at the cell surface. The proteoglycan may play a central role in assembly of such complexes since heparan sulfate has been shown to interact with both fibronectin and laminin. 相似文献
7.
Alterations in Pigment Content in Leaves of Pisum sativum After Exposure to Supplementary UV-B 总被引:6,自引:0,他引:6
Pea plants were either illuminated with visible light supplementedwith ultraviolet-B (UV-B) radiation for five days, or transferredback to control light after short exposures (hours) to UV-B.Spectra of NaOH-extracted pigments from UV-B-exposed plantsshowed a decrease in absorption in the visible region and anincrease in the UV region: the former a consequence of the lossof chlorophyll, the latter probably due to induced synthesisof protective pigments. The decrease in chlorophyll absorptionwas an earlier event than the increase in UV absorption. Inextracts from plants which had recovered, the increase in UVabsorption was greater than in leaves subjected to three daysof UV-B. This stresses the importance of recovery from UV-Bfor extensive synthesis of protective pigments. Analysis oftetrapyrrolic pigments showed that UV-B treatment caused noallomerization of chlorophylls. Formation of chlorophyllidesa and b was greatly enhanced during the degradation of chlorophylls;however, the concentrations of chlorophyllides were three ordersof magnitude lower than those of the chlorophylls and did notincrease greatly as chlorophyll degradation progressed. No protoporphyrinIX, uro- or copro-porphyrins III were detected, which suggeststhat early steps in chlorophyll synthesis are not affected byUV-B light. (Received May 15, 1992; Accepted August 6, 1992) 相似文献
8.
Fritz A. Henn Rick Venema David Anderson Ake Sellstrom 《Journal of neurochemistry》1980,34(6):1671-1677
Abstract: An isolated fraction of Purkinje perikarya was prepared. This fraction had [3 H]GABA receptor binding and [3 H]muscimol binding analogous to that reported for heterogeneous cerebellar membranes. The finding of two binding components with each ligand suggests that these components do not represent two binding sites, one presynaptic and the other postsynaptic, since both are clearly seen on purified Purkinje cell bodies. Subcellular fractionation indicates that synaptic endings and plasma membranes are enriched in GABA receptors compared with intracellular organelles. Purkinje cell bodies were also found to possess a high-affinity transport system for GABA, which was sensitive to inhibition by diaminobutyric acid (DABA) but not by β-alanine. They showed no evidence of homoexchange (the movement of label without net transport). This supports our suggestion that homoexchange is an artifact of synaptic particle formation. 相似文献
9.
Bjrn Odlander Jan Ake Lindgren Hans-Erik Claesson 《Prostaglandins & other lipid mediators》1987,34(4)
Incubation of human leukocytes with opzonized zymosan or IgG immune complexes led to a time dependent release of leukotrienes (LT) B4 and C4. After 3–4 min, the levels of LTB4 and LTC4 were 93 and 35 pmol/3107 cells, respectively. These amounts were 2–4 times lower than those released by leukocytes stimulated with the calcium ionophore A 23187. The levels of LTC4 were 8 and 20 times lower than those of LTB4 after incubation with opsonized zymosan or immune complexes, respectively. Heat-inactivation of the serum prior to zymosan coating decreased the effect of opsonized zymosan. Uncoated zymosan was an even weaker stimulus of leukotriene formation. These results suggest that both complement factors and immunoglobulins play a pivotal role in activating leukotriene synthesis in a mixed suspension of human leukocytes. 相似文献
10.
Heiskanen T Li XD Hepojoki J Gustafsson E Lundkvist A Vaheri A Lankinen H 《Protein engineering》2003,16(6):443-450
We have previously selected a peptide insert FPCDRLSGYWERGIPSPCVR recognizing the Puumala virus (PUUV) G2-glycoprotein-specific neutralizing monoclonal antibody (MAb) 1C9 with Kd of 2.85 x 10(-8) from a random peptide library X2CX14CX2 expressed on the pIII protein of the filamentous phage fd-tet. We have now created a second-generation phage-displayed peptide library in which each amino acid of the peptide was mutated randomly to another with a certain probability. Peptides were selected for higher affinity for MAb 1C9 and for a common binding motif for MAb 4G2 having an overlapping epitope with MAb 1C9 in G2 glycoprotein. The resulting peptides were synthesized as spots on cellulose membrane. Amino acid changes which improved the reactivity of the peptides to MAb 1C9 were combined in the peptide ATCDKLFGYYERGIPLPCAL with Kd of 1.49 x 10(-9) in biosensor measurements. Our results show that the binding properties of peptides, the affinity and the specificity can be improved and the binding specificity determining amino acids and structural factors can be analyzed by combining binding assays with synthetic peptides on membrane with the use of second-generation phage display libraries. 相似文献