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Ossi Renkonen Ritva Niemelä Anne Leppänen Hannu Maaheimo Antti Seppo Leena Penttilä Anja Vilkman 《Glycoconjugate journal》1991,8(4):368-375
Radiolabelled GlcNAc beta 1-3(GlcNAc beta 1-6)Gal (1), GlcNAc beta 1-3)GlcNAc beta 1-6)Gal beta 1-OCH3 (4), GlcNAc beta 1-3(GlcNAc beta 1-6)Gal beta 1-4Glc (7), and GlcNAc beta 1-3(GlcNAc beta 1-6)Gal beta 1-4GlcNAc (10) were cleaved partially with jack bean beta-N-acetylhexosaminidase (EC 3.2.1.30), and the digests were analysed chromatographically. All four oligosaccharides were hydrolysed faster at the (1-6) branch, than at the (1-3) branch, but a high branch specificity was observed only with the glycan 4. The saccharides 1 and 7 resembled each other in the kinetics of the enzyme-catalysed release of their two non-reducing N-acetylglucosamine units, but the glycan 10 was rather different. The partial digestions made it possible to obtain radiolabelled GlcNAc beta 1-6Gal, GlcNAc beta 1-6Gal beta 1-OCH3, GlcNAc beta 1-6Gal beta 1-4Glc, and, in particular, GlcNAc beta 1-6Gal beta 1-4GlcNAc. 相似文献
3.
Deficient production of lysyl oxidase in cultures of malignantly transformed human cells 总被引:3,自引:0,他引:3
Lysyl oxidase activity in the culture medium of eight malignantly transformed human cell lines was very low compared with that in four control fibroblast lines, being 9-16% in five sarcoma cell lines and 7-11% in three other tumour cell lines. The low enzyme activity was probably due to deficient enzyme synthesis rather than impaired secretion into the cell medium, as low activity was also found in urea extracts of the cell pellets. Lysyl oxidase production thus appears to be closely regulated with deficient collagen gene expression in malignant transformation. 相似文献
4.
Fibronectin is expressed by astrocytes cultured from embryonic and early postnatal rat brain 总被引:9,自引:0,他引:9
In early primary cultures from newborn rat brain, few glial fibrillary acidic protein (GFAP)-positive glial cells expressed intracytoplasmic immunoreactivity for fibronectin. After the second week in culture, however, fibronectin was expressed by a distinct population of GFAP-positive flat astrocytes, irrespective of which brain region was studied. In cerebellar cultures, these cells were more abundant than in cortical or neostriatal cultures and often formed a major population of the GFAP-positive cells. The difference in fibronectin expression between cerebellum and the other areas studied was statistically significant. When cultures were started from 9-day-old postnatal rat brain, fibronectin-positive astrocytes appeared earlier than in those from newborn animals, in all areas studied. Further, especially in the case of cerebellum, the number of fibronectin-positive astrocytes increased as a function of time in culture. In cultures started from whole brains of 12-day-old rat embryos, fibronectin was expressed within 24 h in culture by all the cells with morphology of flat astrocytes, positive for vimentin but negative for GFAP. These results indicate that astrocytes cultured from newborn and early postnatal rat brain are a heterogeneous population of cells: depending on the brain region studied and also depending on the age of brain tissue or the time in culture, less than 1-60% of the GFAP-positive flat astrocytes expressed fibronectin. This, together with the fact that fibronectin was present in early embryonic brain cells in culture, suggests that fibronectin may be a prerequisite for the development or interactions of brain cells. 相似文献
5.
Antti Huunan-Seppälä 《Journal of bioenergetics and biomembranes》1971,2(3-4):197-207
The effect of the polybasic substances Polybrene and spermine on the passive and active transport of monovalent cations in mitochondria was studied. These agents were found to stimulate the low amplitude swelling of mitochondria. Volume oscillations were induced by addition of substrate in the presence of spermine. In conditions where weak oscillations were obtained without these substances, oscillations were stimulated and their frequencies increased in the presence of Polybrene and spermine. Their effects were maximal with 100–300 moles spermine per litre and 3–5 mg Polybrene per litre. These results are discussed in relation to an interaction of the agents studied with membrane negative charges which may be important regulators of ion transport. 相似文献
6.
Antti Hervonen Lasse Kanerva Anja H. Tissari Birgit V. A. Suurhasko 《Cell and tissue research》1974,148(4):535-550
Summary The ultrastructure and protein content of the five subfractions of the crude mitochondrial fraction from the brain stem of the 1-day old and adult rat was examined. The morphological composition of the subfractions after fixation in glutaraldehyde and osmiumtetroxide in the adult rat brain stem resembled that previously reported for the whole brain; synaptosomes sedimented in a sucrose gradient in subfractions C and D. In the 1-day old rat, mature synaptosomes were found in subfractions A, B, C and D; E contained mainly free mitochondria. 80–95% of the processes in the adult and 10–30% in the 1-day old rat contained synaptic vesicles which were of four types: (1) small agranular vesicles (2) large dense core vesicles (3) large agranular vesicles (4) coated vesicles. Pre- and postsynaptic membrane thickenings were demonstrated in many nerve-ending particles. In the subfractions of the 1-day old rat the protein content was one half and the distribution resembled that in the adult. Evidently nerve endings develop faster in the brain stem than in cortical areas; a serotoninor adrenergic origin of the early synaptosomes is suggested.This study was supported by a grant from the Paulo Foundation. 相似文献
7.
Growth control in chick embryo fibroblasts; no evidence for a specific role for cyclic purine nucleotides 总被引:2,自引:0,他引:2
Cyclic AMP and cyclic GMP concentrations were measured in cultures of normal chick embryo fibroblasts and those transformed by Rous sarcoma virus under different growth conditions. No significant and reproducible correlation between the nucleotide levels and the rate of proliferation was observed. Neither release of normal cells from density dependent inhibition of growth nor transformation of the cultures by different strains of Rous sarcoma virus affected the concentrations of cyclic AMP or cyclic GMP. Activities of cellular cyclic nucleotide phosphodiesterases, enzymes involved in regulating the level of the nucleotides, were not directly affected by growth-stimulating concentrations of insulin or neuraminidase. Growth stimulation by insulin did not alter the activities of cellular cAMP-dependent protein kinase. These results do not support the hypothesis that cyclic AMP or cyclic GMP has a specific role in the growth control of chick embryo fibroblasts. 相似文献
8.
Antti Penttilä 《Cell and tissue research》1969,102(2):193-204
Summary Methods for light and electron microscopic comparison of individual argentaffin and argyrophil enterochromaffin cells (EC) in the sheep duodenal mucosa are described. These silver procedures were applied for light microscopy to Epon-embedded sections. The adjacent sections were examined with the electron microscope. The most specific characteristics of the argentaffin and argyrophil EC in electron microscopy are highly osmiophilic cytoplasmic granules. In one cell type these granules are smaller and more roundish than in the another type. These two cell types are stainable both by the argentaffin and argyrophil reactions. No essential difference can be observed in the localization of these elements. It is suggested that both cell types belong to the enterochromaffin system. Both silver methods are also suitable for the light microscopic identification of other intestinal structures in sections adjacent to that sectioned for electron microscopy.This work was supported by a grant from the Yrjö Jahnsson Foundation, Helsinki, Finland.The electron microscopic observations were carried out in the Electron Microscope Laboratory, University of Helsinki. 相似文献
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10.
Factors Influencing the Enhancement of the Infectivity of Poliovirus Ribonucleic Acid by Diethylaminoethyl-Dextran 总被引:22,自引:9,他引:13
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The enhancement by diethylaminoethyl-dextran (DEAE-D) of the infectivity of poliovirus ribonucleic acid (RNA) for cell cultures was demonstrated by infective-center as well as by plaque assays, both in nonprimate (L) and primate cell systems (MK, HeLa, LLC-MK(2)). The sensitivity of plaque assays was greatly improved by using a tris (hydroxymethyl)aminomethane-buffered synthetic medium (basal medium Eagle) and freshly confluent cell monolayers. Enhancement of nucleic acid infectivity was directly dependent on the molecular weight of the DEAE-D. Two observations bearing on the action of DEAE-D appeared important: ribonuclease activity was reduced by DEAE-D, and cells pretreated with DEAE-D remained susceptible to infection with RNA in isotonic medium. Appreciable susceptibility of the treated cells persisted for at least 2 hr; the susceptible state could be reversed at will by an application of heparin. Enhancement of nucleic acid infectivity was independent of an effect of DEAE-D on intact virus and agar inhibitors. 相似文献