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891.
Two-dimensional crystals of avidin were obtained on mixed lipid monolayers containing biotinylated lipids (N-biotinyl-dipalmitoyl-L-alpha-phosphatidyl ethanolamine and dioleoyl phosphatidyl choline) by specific interaction. Image analysis of electron micrographs of these crystals revealed p2 symmetry with the unit cell parameters a = 66 +/- 2 A, b = 68 +/- 1 A, and gamma = 121 +/- 4 degrees. The projection map showed, at a resolution of about 27 A, that the four subunits within one avidin molecule are separated into two parts. Comparison between avidin and streptavidin reveals that avidin molecule binds to the lipid monolayer in an orientation similar to that of streptavidin. 相似文献
892.
893.
Immunoadsorption test was used for determination of the strainspecificity of antibody to a new antigenic variant of influenza B virus (B/Hong Kong/5/72 and B/Yamagata/1/73) in human sera collected in April, 1973--March, 1974. The new strains were shown to be circulating in Moscow City only late in February and in March 1974. The experimental data show the immunoadsorption test to give more definite ideas not only on the qualitative differences between strains but also on the specificity of the immunologic response. 相似文献
894.
Persisting primitive papilla epithelialis is described in a 22-year-old woman. The papilla has blurred borders, a central papilla eminence and a yellowish colour. In addition pigmentary pseudoretinopathy with perivascular pigment deposits and hypermetropia with aplasia maculae occurred. This picture can be confused classically with pappilloedema. 相似文献
895.
We are interested in identifying the pathways which are responsible for triggering the conditioned enhancement of natural killer (NK) cell activity. Earlier studies have suggested that central opioid(s) are involved in eliciting the expression of the conditioned NK cell activity. The purpose of this study was to identify the central opioid peptides that allow the central nervous system (CNS) to communicate with the immune system. Mediators that activate the efferent pathway of communication between the CNS and immune system was examined by injection of the mediator via the cisterna magna (CM). Conditioning was used as a tool to show that the bi-directional communication between the CNS and the immune system does take place. We found that beta-endorphin but not dynorphin could stimulate NK cell activity, when beta-endorphin or dynorphin was injected into the CM. In addition, when anti-beta-endorphin or anti-dynorphin antibody was injected into the conditioned animals via CM the conditioned response was blocked by anti-beta-endorphin but not by anti-dynorphin antibody. These observations suggest that beta-endorphin appears to be one of the signals that is induced in the brain at the CS recall step of the conditioned response to trigger the elevation of NK cell activity. 相似文献
896.
A tributyltin chloride (TBTCl)-resistant bacterium, Alteromonas sp. M-1, was isolated from coastal seawater. This bacterium grew in medium containing 125 microM TBTCl. TBTCl added to the medium was taken up by this bacterium, however, the amount of TBTCl in the cellular fraction was low after the logarithmic phase, suggesting the existence of a TBTCl-efflux system. A genetic library was constructed using plasmid vector pUC 19. Three positive clones were obtained, by which E. coli was transformed to TBTCl resistance. Of the three clones, the shortest fragment from HindIII-library was analyzed. This fragment was 1.8 kb long and contained one complete open reading frame. The predicted amino acid sequence of this open reading frame had a homologous domain to transglycosylases of bacteriophage and E. coli. TBTCl-tolerant marine bacteria other than Alteromonas sp. M-1 were obtained from natural seawater to which TBTCl was added. DNA-DNA hybridization was performed between the three cloned fragments from Alteromonas sp. M-1 and chromosomal DNA of the TBTCl-tolerant bacteria. Some strains hybridized with the fragments and some did not, suggesting that several genes are responsible for TBTCl tolerance. 相似文献
897.
A working model for the histogenesis of carcinoma of the uterine cervix is summarized in Table I. The inclusion of squamous metaplasia in this chart does not imply that this reaction falls into the spectrum of cervical neoplasia or is necessarily an antecedent to neoplasia. It does simply imply that the carcinogenic event or events apparently occur in or involve an epithelium that is indistinguishable from squamous metaplasia. The chart intentionally implies that the lesions mentioned are not separate diseases but arbitrary points in the spectrum of cervical neoplasia. It must be emphasized that one stage does not necessarily progress to the next and that at any stage up to indisputable cancer the changes may regress, persist or progress. The careful evaluation of histologic material from the uterine cervix will permit the pathologist to exclude those epithelial abnormalities which are not a part of the spectrum of cervical neoplasia and allow him or her to place the patient with cervical neoplasia at the proper stage in the development of the process. With this information the clinician can then intelligently plan appropriate therapy. 相似文献
898.
T Konstadinidis JE Souza VF Fontes AL Azevedo SF Assis JS Guimar?es HG Carvalho AD Jatene 《Canadian Metallurgical Quarterly》1976,29(1):13-17
A practical procedure for hypophysectomy of the mouse by paraphyaryngeal approach has been developed by modifying the technics of Motizuki [5] and Lostroh and Jordan [4]. Postoperative care in C3H/He strain of female mice was also studied. The main points improved are as follows: (a) The dental drill bar made of a needle with 2mm outer diameter was devised for making a hole in the cranium (Fig. 2). The bar does not grind the cranium, but cuts it in the circle, resulting in speeding up of the operation and in little bleeding, since the hole is very small. (b) Special attention was paid in breathing of mice during the operation. A longitudinal midline incision of about 1cm was made in muscle encircled the trachea and a pinhole was made by sewing needle into the trachea. A small piece of cotton wool was put on the pinhole and covered by the muscle. It admirably keeps the tracheal hole open for breathing during operation (Fig. 1). (c) After the operation, the mouse was placed in a chamber filled with an atmosphere of 95% O2-5%CO2 gas until recovered, otherwise, all mice died in a few days after operation with inflamation of the lung. The temperature of the recovery chamber is recommended to be kept at about 28 degrees C for ensuring the resuscitation. The intraperitoneal injections of hydrocortone-acetate (0.25mg/0.1ml) just before and 2 days after operation further ameriolated the survival rate. 相似文献
899.
900.
C Mulle A Sailer I Pérez-Ota?o H Dickinson-Anson PE Castillo I Bureau C Maron FH Gage JR Mann B Bettler SF Heinemann 《Canadian Metallurgical Quarterly》1998,392(6676):601-605
L-glutamate, the neurotransmitter of the majority of excitatory synapses in the brain, acts on three classes of ionotropic receptors: NMDA (N-methyl-D-aspartate), AMPA (alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid) and kainate receptors. Little is known about the physiological role of kainate receptors because in many experimental situations it is not possible to distinguish them from AMPA receptors. Mice with disrupted kainate receptor genes enable the study of the specific role of kainate receptors in synaptic transmission as well as in the neurotoxic effects of kainate. We have now generated mutant mice lacking the kainate-receptor subunit GluR6. The hippocampal neurons in the CA3 region of these mutant mice are much less sensitive to kainate. In addition, a postsynaptic kainate current evoked in CA3 neurons by a train of stimulation of the mossy fibre system is absent in the mutant. We find that GluR6-deficient mice are less susceptible to systemic administration of kainate, as judged by onset of seizures and by the activation of immediate early genes in the hippocampus. Our results indicate that kainate receptors containing the GluR6 subunit are important in synaptic transmission as well as in the epileptogenic effects of kainate. 相似文献