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Evidence for a Ca2+-independent association between calpain II and phospholipid vesicles 总被引:1,自引:0,他引:1
Possible interactions between calpain II and phospholipids such as phosphatidylinositol, phosphatidylserine and phosphatidylcholine were studied using fluorescence and gel filtration techniques. Changes in fluorescence intensity of purified calpain II show that the enzyme strongly interacts with phosphatidylinositol and phosphatidylserine and to a lesser extent with phosphatidylcholine. These results are corroborated by the gel filtration technique which permits the isolation of the enzyme phospholipid complex. Association between calpain II and various phospholipid vesicles can occur in the absence of calcium. Such binding occurs without any observable change of the molecular mass of the two subunits on SDS-polyacrylamide gel electrophoresis. 相似文献
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P Cottin S Poussard D Mornet J J Brustis M Mohammadpour J Leger A Ducastaing 《Biochimie》1992,74(6):565-570
Dystrophin is a cytoskeletal protein which is thought to play an important role in membrane physiology since its absence (due to gene deficiency) leads to the symptoms of Duchenne muscular dystrophy (DMD). Some disruption in the regulation of intracellular free Ca2+ levels could lead to DMD-like symptoms. In this study, calpains, which are very active calcium-dependent proteases, were examined for their capacity to hydrolyse dystrophin in vitro. The results show that calpains are able to split dystrophin and produce breakdown products of different sizes (the degree of cleavage being dependent on the incubation time with proteases). The time-course of protease degradation was examined by Western immunoblot using three polyclonal sera which were characterized as being specific to the central (residues 1173-1728) and two distal parts of the molecule ie specific to the N-terminal (residues 43-760) or the C-terminal (residues 3357-3660) extremities of the dystrophin molecule. The cleavage patterns of dystrophin showed an accumulation of some major protease-resistant fragments of high relative molecular mass (250-370 kDa). These observations demonstrate that calpains digest dystrophin very rapidly when the calcium concentration is compatible with their activation. For instance, it is clear that calpains first give rise to large dystrophin products in which the C-terminal region is lacking. These observations suggest that dystrophin antibodies specific to the central domain of the molecule should be used to detect dystrophin for diagnostic purposes and before any conclusion as to the presence or absence of dystrophin can be deduced from results obtained using immunoanalyses of muscle biopsies. 相似文献
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Crepis dinarica andC. froelichiana are two closely related species of theC. praemorsa complex. Even though they exhibit the same chromosome number (2n = 8) and similar idiogram shape, they differ widely in quantity and distribution of heterochromatin bands. The hybrids between these two species comprise three morphological types. Parental genomes were distinguished in hybrids by Giemsa differential staining (C-banding). Although meiosis presents only a few abnormalities (about 2.4%), the percentage of aborted pollen grains is very high (90%). 相似文献
7.
Hemagglutination Inhibition with Arboviruses: Relationship Between Titers and Source of Erythrocytes 下载免费PDF全文
Antigens for Grand Arbaud, Hazara, and California arboviruses were able to agglutinate goose and either dog, hamster and guinea pig, or hamster red blood cells (RBC) to the same titer at the same pH; in hemagglutination-inhibition (HI) tests, titers for homologous and related sera were the same with these different types of RBC or occasionally one dilution higher with the mammalian cells. Antigens for St. Louis encephalitis and Eastern equine encephalitis viruses required use of lower antigen dilutions with human, guinea pig, and hamster RBC than with goose RBC. The results of comparative HI testing with these latter antigens and types of RBC indicate that HI titer is not directly related to the antigen dilution used with different types of RBC. 相似文献
8.
Functional Expression of P-Glycoprotein in an Immortalised Cell Line of Rat Brain Endothelial Cells, RBE4 总被引:5,自引:3,他引:2
David J. Begley Delphine Lechardeur Zheng-Duan Chen Christopher Rollinson †Michèle Bardoul †Françoise Roux Daniel Scherman N. Joan Abbott 《Journal of neurochemistry》1996,67(3):988-995
Abstract: The presence of P-glycoprotein in the cell plasma membrane limits the penetration of many cytotoxic substances into cells that express the gene product. There is considerable evidence also to indicate that P-glycoprotein is expressed as part of the normal blood-brain barrier in the luminal membranes of the cerebral capillary endothelial cells, where it presumably performs a protective function for the brain. This report describes the functional expression of P-glycoprotein in an immortalised cell line, RBE4, derived from rat cerebral capillary endothelial cells. The expression of P-glycoprotein is demonstrated by western immunoblotting and by immunogold and fluorescent staining with monoclonal antibodies. The cellular accumulation of [3 H]colchicine and [3 H]vinblastine is investigated and shown to be enhanced by the presence of azidothymidine, chlorpromazine, verapamil, cyclosporin A, and PSC 833 ([3'-keto-Bmt1 ]-[Val2 ]-cyclosporin) at 50 or 100 µ M concentration. It is concluded that the RBE4 cell line is a valuable tool for investigating the mechanisms of P-glycoprotein activity both in the blood-brain barrier and in multidrug resistance in general. 相似文献
9.
Resonance Raman experiments were performed on different green bacteria. With blue excitation, i.e. under Soret resonance or preresonance conditions, resonance Raman contributions were essentially arising from the chlorosome pigments. By comparing these spectra and those of isolated chlorosomes, it is possible to evaluate how the latter retain their native structure during the isolation procedures. The structure of bacteriochlorophyll oligomers in chlorosomes was interspecifically compared, in bacteriochlorophyllc- and bacteriochlorophylle- synthesising bacteria. It appears that interactions assumed by the 9-keto carbonyl group are identical inChlorobium limicola, Chlorobium tepidum, andChlorobium phaeobacteroides. In the latter strain, the 3-formyl carbonyl group of bacteriochlorophylle is kept free from intermolecular interactions. By contrast, resonance Raman spectra unambiguously indicate that the structure of bacteriochlorophyll oligomers is slightly different in chlorosomes fromChloroflexus auranticus, either isolated or in the whole bacteria. 相似文献
10.
Lucie Mahaut Philippe Choler Pierre Denelle Eric Garnier Wilfried Thuiller Jens Kattge Servane Lemauviel-Lavenant Sandra Lavorel François Munoz Delphine Renard Josep M. Serra-Diaz Nicolas Viovy Cyrille Violle 《Global Ecology and Biogeography》2023,32(4):561-572