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41.
E. GHANEM 《Cell biology international》1996,20(10):681-685
Embryonic chick notochords were studied during their metabolically active and involuting periods for the expression of collagen type I and II. The staining was carried out on notochords in vivo at stage 20 and stage 35 and on mesenchyme-contaminated and mesenchyme-free notochords at stage 20, which were cultured in vitro for 6 days. The results show that type II collagen is demonstrable in the notochords, at all the examined stages, both in vivo and in vitro. However, the expression of type I collagen was stage-dependent in vivo and in vitro. At stage 20, the perinotochordal sheath is positively immunostained for collagen type I, but the notochord itself is negative. At stage 35, the perinotochordal sheath as well as the notochord are positively immunostained for collagen type I. The mesenchyme-contaminated and the mesenchyme-free notochords and their sheaths are also positively immunostained for the type I collagen after6 days in vitro. The current results, at late developmental stages, indicate that the involuting notochords express collagen type I, which seems not to be altered by changing the micro-environment in vivo. 相似文献
42.
David Cowburn 《Current opinion in structural biology》1997,7(6):835-838
Protein tyrosine binding (PTB) and ‘post synaptic density disc-large zo-1’ (PDZ) domains bind to short peptidic ligands by augmentation of one of the domain's β sheets and other recognition mechanisms. The two domain classes have a superficial resemblance to each other, even though no sequential homology exists. The structural bases of the interactions are well understood for the domains now experimentally determined, and ligand—target pairs can probably be identified in favorable cases by analogy with the known domains. For both PTB and PDZ classes, functional activities are still not fully defined: it is possible that these domain classes, along with pleckstrin homology domains, have multiple roles. 相似文献
43.
44.
45.
Aortal collagen typing in monkey and man showed the presence of types I, HI and V in human aorta and types I and III in monkey
aorta. Type III collagen was found to be a predominate type in both species. The molecular weight of type III collagen was
similar in these species while type I collagen was different. Both monkey and human collagen types I and III were found to
be immunogenic. Type I collagen was significantly increased while type III was decreased in human atherosclerotic plaque.
Collagen typing in fatty streak remained unaltered. 相似文献
46.
Type IX collagen, a recently discovered, unusual protein of cartilage, has a segmented triple-helical structure containing interchain disulfides. Its polymeric form and function are unknown. When prepared by pepsin from bovine articular cartilage, type IX collagen was found to contain a high concentration of hydroxypyridinium cross-links, similar to that in type II collagen. Fluorescence spectroscopy located the hydroxylysyl pyridinoline and lysyl pyridinoline cross-linking residues exclusively in the high-molecular-weight collagen fraction, from which they were recovered predominantly in a single CNBr-derived peptide. The results point to a structural role for type IX collagen in cartilage matrix, possibly as an adhesion material to type II collagen fibrils. 相似文献
47.
Precipitation of collagens by polyethylene glycols 总被引:2,自引:0,他引:2
Types I, II, and III collagens are readily precipitated at neutral pH by polyethylene glycols (PEG). As the molecular weight fraction of the polyethylene glycols increases, they become more effective as precipitants on a weight basis. The amount of PEG required for precipitation depends on the pH, the ionic strength, and the nature of the buffer or salts present. In tissue culture media, low concentrations of collagens and procollagens may be quantitatively precipitated and readily collected by low-speed centrifugation. Polyethylene glycol precipitation can be used to obtain collagens and procollagens from tissue culture media at either analytical or preparative scale, and since the polyethylene glycols do not bind to collagens, the precipitates may be further analyzed directly by chromatographic or electrophoretic methods. 相似文献
48.
A new cell culture microcarrier that can be covalently bonded by cell attachment proteins and can be thin-sectioned for electron microscopy was synthesized. It was easily made by sulfonating cross-linked polystyrene beads for a negative surface charge followed by covalent attachment of polyethylenimine for a positive charge. Cell attachment proteins, e.g. collagen, was covalently bonded directly to the microcarrier using a carbodiimide or after activating the microcarrier surface with glutaraldehyde. HeLa-S3 cells attached, spread and grew to confluence more efficiently on the positive microcarriers and those coated with collagen than on the negative ones. Endothelial cells grew best on those with a negative surface charge. The nature of the microcarrier surface was not the only aspect involved in cell adhesion but also the type of serum proteins adsorbed. Qualitatively different proteins coated the microcarriers depending upon whether the carrier was negative, positive or coated with collagen. Comparison of various types of available microcarriers indicated that the modified cross-linked polystyrene beads used here were best for transmission and scanning electron microscopy. Endothelial cells grown on the microcarriers had the same ultrastructure as cells grown in monolayers in culture dishes. Of a variety of microcarriers tested the modified cross-linked polystyrene beads were the only ones that could be used for both ultrastructural and biochemical techniques. 相似文献
49.
Joanne T. Emerman Dorothy R. Pitelka 《In vitro cellular & developmental biology. Plant》1977,13(5):316-328
Summary Dissociated normal mammary epithelial cells from prelactating mice were plated on different substrates in various medium-serum-hormone
combinations to find conditions that would permit maintenance of morphological differentiation. Cells cultured on floating
collagen membranes in medium containing insulin, hydrocortisone and prolactin maintain differentiation through 1 month in
culture. The surface cells form a continuous epithelial pavement. Some epithelial cells below the surface layer rearrange
themselves to form alveolus-like structures. Cells at both sites display surface polarization; microvilli and tight junctions
are present at their medium-facing or luminal surface and a basal lamina separates the epithelial components from the gel
and stromal cells. Occasinal myoepithelial cells, characterized by myofilaments and plasmalemmal vesicles, are identified
at the basal surface of the secretory epithelium. In contrast, cells cultured on plastic, glass or collagen gels attached
to Petri dishes form a confluent epithelial sheet showing surface polarization, but lose secretory and myoepithelial specializations.
If these dedifferentiated cells are subsequently maintained on floating collagen membranes, they redifferentiate. There is
little DNA synthesis in cells on collagen gels, in contrast to Petri-dish controls. Protein synthesis in cells on floating
collagen membranes increases over T0 values and remains constant through 7 days in culture whereas it decreases on attached gels; however, if the gels are freed
to float, protein synthesis increases sharply and parallels that seen on floating membranes.
The work was supported by USPHS Grants CA-05388 and CA-05045 from the National Cancer Institute, DHEW. 相似文献
50.
Armelle Baeza-Squiban Sylvie Romet Anne Moreau Francelyne Marano 《In vitro cellular & developmental biology. Animal》1991,27(6):453-460
Summary Primary cultures of rabbit tracheal cells were obtained as outgrowths from explants of tracheal mucosa. A 30% collagen substratum
containing serum and minimal essential medium was required for obtaining an outgrowth of epithelial cells keeping their differentiated
characteristics. The tracheal epithelial cells obtained near the explant in the first days of culture presented morphologic
similarities with normal tracheal epithelium. Cultures contained basal cells and epithelial polarized cells that exhibited
apical tight junctions and desmosomes. Ciliated cells stayed functional during all time culture. Their number slightly increased
at the beginning of the culture and then stayed constant when the total number of cells increased. Development of the outgrowth
was rapid and significant inasmuch as the outgrowth surface reached 30 times that of the explant after less than 8 days. This
was linked to cellular proliferation, as demonstrated by the incorporation of bromodeoxyuridine (BrdU) in phase-S nuclei and
the revelation of BrdU using an immunofluorescence technique. The epithelial nature of the outgrowth cells and the absence
of contamination with fibroblasts were established by positive staining with anti-keratin antibody and by negative staining
with anti-vimentin antibody, respectively.
This work was supported by DRET and by CIFRE grant awarded to S. R. 相似文献