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61.
There is some discussion as to whether glycosyl-phosphatidylinositol(GPI)-anchored proteins occur in microdomains in the cell membrane. These putative microdomains have been implicated in processes such as sorting in polarized cells and signal transduction. Complexes enriched in GPI-anchored proteins, cholesterol and glycosphingolipids have been isolated from cell membranes by using non-ionic detergents: these complexes were thought to represent a clustered arrangement of GPI-anchored proteins. However, results obtained when clustering of GPI-anchored proteins induced by antibodies or by detergents was prevented support the idea of a dispersed surface distribution of GPI-anchored proteins at steady state. Here we use chemical crosslinking to show that membrane microdomains of a GPI-anchored protein exist at the surface in living cells. This clustering is specific for the GPI-anchored form, as two transmembrane forms bearing the same ectodomain do not form oligomers. Depletion of membrane cholesterol causes the clustering of GPI-anchored proteins to break up, whereas treatment of cells with detergent substantially increases the size of the complexes. We find that in living cells these GPI-anchored proteins reside in microdomains consisting of at least 15 molecules, which are much smaller than those seen after detergent extraction. 相似文献
62.
Fifty subjects with a history of traumatic brain injury (TBI) and/or substance use, completed neuropsychological measures of short and long term verbal and visual memory, information processing, motor speed and co-ordination, executive functioning, and malingering. All subjects performed below norms on tests of verbal memory and verbal abstract thinking, but overall no differences were found due to either severity of TBI or level of substance use. Maori subjects obtained the lowest scores on tests of verbal ability, but also reported higher rates of TBI and substance use, which is presumed to account for this result. In conclusion, prison populations seem to have disproportionately high rates of TBI, recurrent TBI, and substance use, compared to the general population. Further, there are a group of individuals who have experienced both TBI and substance abuse, with associated impairments in verbal memory and learning, abstract thinking, and who report problems with general memory and socialization. These difficulties may affect functioning both in prison and following release. 相似文献
63.
OE Surnina VI Lupandin OS Silivanova TV Zvereva 《Canadian Metallurgical Quarterly》1997,47(4):658-663
Two groups of children (5-6-year-old and 7-8-year-old) were presented with pairs of sound signals of the same or different durations. Sound signal durations in pairs could be 1.0, 1.2, 1.5, and 2.0 sec. The children had to detect the difference between the sounds in a pair. The obtained data were compared to the analogous results shown by the 18-39-year-old subjects. It was found out that the ability to discriminate intervals of short duration substantially improved with age. This phenomenon in presumably connected with perfection of the short-term memory. Independently of the subject's age, the order of presentation of signals in a pair influences the ability to discriminate between their durations. 相似文献
64.
Severe defects in immunity and hematopoiesis caused by SHP-1 protein-tyrosine-phosphatase deficiency
Spontaneous mouse mutations that cause severe immunodeficiency or autoimmunity are invaluable tools with which to investigate the mammalian immune system. Mutations at the 'motheaten' locus result in severe immunological dysfunction due to disruption of the structural gene encoding Src-homology 2-domain phosphatase-1 (SHP-1). This natural model for a specific protein-tyrosine-phosphatase deficiency is being widely utilized to determine the role of SHP-1 in the negative regulation of multiple signaling pathways in a number of hematopoietic lineages. 相似文献
65.
66.
A considerable decrease in pressor responses to polyglykine at an elevated arterial tone and constant increase of cardiac output occurred in anesthetised rats. Vascular and cardiac mechanisms of the interrelationship are discussed. 相似文献
67.
68.
Endoscopic perforator vein division with ablation of superficial reflux improves venous hemodynamics
JM Rhodes P Gloviczki L Canton TV Heaser TW Rooke 《Canadian Metallurgical Quarterly》1998,28(5):839-847
Plant responses to high salt stress have been studied for several decades. However, the molecular mechanisms underlying these responses still elude us. In order to understand better the molecular mechanism related to NaCl stress in plants, we initiated the cloning of a large number of NaCl-induced genes in Arabidopsis. Here, we report the cloning of a cDNA encoding a novel Ca2+-binding protein, named AtCP1, which shares sequence similarities with calmodulins. AtCP1 exhibits, in particular, a high degree of amino acid sequence homology to the Ca2+-binding loops of the EF hands of calmodulin. However, unlike calmodulin, AtCP1 appears to have only three Ca2+-binding loops. We examined Ca2+ binding of the protein by a Ca2+-dependent electrophoretic mobility shift assay. A recombinant AtCP1 protein that was expressed in Escherichia coli did show a Ca2+-dependent electrophoretic mobility shift. To gain insight into the expression of the AtCP1 gene, northern blot analysis was carried out. The AtCP1 gene had a tissue-specific expression pattern: high levels of expression in flower and root tissues and nearly undetectable levels in leaves and siliques. Also, the expression of the AtCP1 gene was induced by NaCl treatment but not by ABA treatment. Finally, subcellular localization experiments using an AtCP1:smGFP fusion gene in soybean suspension culture cells and tobacco leaf protoplasts indicate that AtCP1 is most likely a cytosolic protein. 相似文献
69.
BA Mannion TV Kolesnikova SH Lin S Wang NL Thompson ME Hemler 《Canadian Metallurgical Quarterly》1998,273(50):33127-33129
The 80/40-kDa CD98 protein complex was purified using an anti-CD98 heavy chain monoclonal antibody coupled to Sepharose beads. Eluted proteins were subjected to preparative SDS-polyacrylamide gel electrophoresis, and protein corresponding to the 40-kDa CD98 light chain was excised. Following proteolysis with trypsin, a peptide fragment was sequenced by mass spectrometry. The nine residues obtained were identical to established C-terminal sequences of the human E16 and rat TA1 proteins, suggesting that TA1/E16 protein is the CD98 light chain. Consistent with this, anti-TA1/E16 antibodies specifically immunoblotted the approximately 35-40-kDa light chain present upon immunoprecipitation of the human CD98 complex. Furthermore, anti-CD98 heavy chain antibody specifically co-immunoprecipitated hemagglutinin-tagged light chain from cells transfected with hemagglutinin-tagged E16 cDNA. In conclusion, the CD98 light chain is identical to the TA1/E16 protein, based on partial amino acid sequence identity, antibody cross-reactivity, genetic reconstitution evidence, similar molecular size, and comparable cell distribution. 相似文献
70.
S Vijayasekaran TV Chirila Y Hong SG Tahija PD Dalton IJ Constable IL McAllister 《Canadian Metallurgical Quarterly》1996,7(8):685-696
A homopolymer of 1-vinyl-2 pyrrolidinone and its copolymer with 2-hydroxyethyl methacrylate, both cross-linked with divinyl glycol, were produced as possible substitutes for the vitreous body of the eye. The hydrated polymers behaved like viscoelastic gels, displaying excellent physical and optical properties. The sterile gels (0.7-1.5 ml) were injected into the vitreous cavity of rabbits, which previously underwent gas-mediated vitrectomy. Clinically, the eyes were quiet, with the exception of transient opacities in the vitreous. After 4 weeks, the operated eyes were enucleated and subjected to histopathological analysis using light and transmission electron microscopy. The common feature in all sections was the invasion of inflammatory cells. Vacuoles containing granular material, assumed to be polymer, were seen in the intercellular spaces of the neural retina, in the retinal pigment epithelium cells, and in macrophages. These findings indicated the fragmentation and phagocytosis of synthetic gels. It appeared that the biodegradation of the internalized polymers did not proceed further, however, the fate of polymers and their usefulness as vitreous substitutes should be investigated through long-term experiments. 相似文献