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排序方式: 共有419条查询结果,搜索用时 15 毫秒
1.
2.
Ipratropium bromide is a synthetic derivative of atropine with little absorption when used in inhalation, and therefore little secondary effects. The authors review its pharmacological properties and therapeutic efficacy in the treatment of asthma in children. Combined nebulized inhalation of ipratropium bromide and beta 2 sympathomimetic results in a more efficient and more sustained bronchodilatation than beta 2 sympathicomimetic alone in the treatment of acute asthma in children. Ipratropium bromide should be usefully introduced in the therapeutic scheme of acute asthma in children. Further studies will be necessary in order to determine its efficacy and tolerance in infants. 相似文献
3.
The Simulation of Impact Loads on Beam-type Structures using a Pseudo-dynamic Procedure 总被引:5,自引:0,他引:5
F. J. Q. Melo J. A. O. Carneiro P. P. Camanho C. L. Tavares A. A. Fernandes 《Strain》2004,40(1):13-23
Abstract: This study proposes an alternate method for the analysis of beams with solid cross-section or built as a framed structure and subjected to transverse impact loads from an external striker. The procedure used in the analysis is a combination of two essential tools using pseudo-dynamic techniques. The method reported here involves only one degree of freedom for the structure modelling and assumes an elastic contact between an external striker and the beam structure, which in reality does not happen. As only one degree of freedom is considered in the analysis, some important limitations are inherent to the method proposed here. Essentially, there is the difficulty of modelling the displacement field associated with the transient structure behaviour accurately, as a consequence of fast-rate impact loads. Another difficulty faced by the method refers to a local structure behaviour associated with contact loads. The present method can deal with large displacements in transversely loaded beams associated to a collapse mechanism having a simple geometry and defined with precision from a single parameter. This ensures reasonable accuracy in the evaluation of the strain energy absorbing capacity of transversely impacted beam structures using a single degree of freedom model in a pseudo-dynamic procedure. 相似文献
4.
The confinement of concrete columns provided by carbon fibre reinforced plastic (CFRP) sheets can be an efficient technique
for their structural strengthening. The principal advantages of this technique are the high strength-to-weight ratio, good
fatigue properties, non-corroding characteristics of the CFRP, and the facility of its application.
An experimental research program, that included tests on 54 short column specimens, was carried out to investigate the gain
in strength and ductility of concrete columns externally confined by CFRP wrapping. The variables studied were the column
cross section shape (circular, square and rectangular) and the amount of confinement expressed in the number of CFRP sheet
layers applied to the models (one or two layers).
On the basis of the obtained results, equations were proposed to calculate the confined concrete strength and the ultimate
confined concrete strain as a function of the confining lateral stress for each of the cross section geometry used, circular,
square and rectangular. The estimations given by these equations and by those from formulas encountered in the literature
were compared with the experimental ones and general conclusions were, finally, drawn.
Résumé Le confinement de colonnes de béton assuré par des feuilles de plastique renforcé par des fibres de carbone (CFRP) peut être une technique efficace pour leur comportement structural. Les principaux avantages de cette technique sont la haute relation résistance-poids, des bonnes propriétés de fatigue, les caractéristiques non-corrosives du CFRP, et la facilité de leur application. Un programme expérimental comprenant des essais sur 54 colonnes courtes fut entrepris en vue de déterminer le gain de résistance et de ductilité de colonnes en béton confinées sur le plan externe en les recouvrant de feuilles de CFRP. Les variables étudiées étaient la forme de la section transversale (circulaire, carrée et rectangulaire), et la quantité de renforcement, mesurée par le nombre de feuilles de CFRP appliquées aux modèles (une ou deux couches). En prenant comme base les résultats obtenus, des équations ont été proposées pour calculer la résistance du béton confiné et sa déformation spécifique ultime en fonction de la contrainte latérale de confinement, pour chaque forme de section transversale utilisée, circulaire, carrée et rectangulaire. Les estimations données par ces équations et celles données par des formules trouvées dans la litérature ont été comparées avec les résultats expérimentaux et des conclusions générales ont finalement été établies.相似文献
5.
ZA Varga JF Thompson JC Locke-Edmunds RN Baird JR Farndon 《Canadian Metallurgical Quarterly》1995,82(6):765-769
The Haemocell S-350 device has recently been introduced for intraoperative autotransfusion. The system uses a novel membrane filter to process shed blood. In the first part of this study a 0.2-micron pore size filter was used in a randomized trial comparing the use of autotransfusion (n = 8) with bank blood controls (n = 9) during aortic reconstruction. This part of the trial was abandoned because of unexpected non-surgical bleeding. Bank blood requirements fell from a median of 3.0 (range 0.0-9.0) units to 1.5 (range 0.0-7.0) units when autotransfusion was used, but these patients had a greater perioperative blood loss (1791 (range 932-3104) versus 1140 (range 440-3840) ml). There was evidence of postoperative heparin excess with an activated partial thromboplastin time ratio of 1.3 (range 0.9-3.0) versus 1.0 (range 1.0-1.2) in controls and an activated clotting time of 206 (range 143-280) versus 137 (range 107-142) s. This was confirmed by raised plasma heparin levels and a prolonged thrombin time normalized by protamine. To improve performance a 0.6-micron pore size filter was studied in ten patients. Filtration efficiency doubled from 19 to 38 per cent. Electron micrographs demonstrated better filter clearance, but 44 per cent of the original concentration of heparin remained in the reinfusate. The S-350 device may be an attractive alternative to centrifugation for intraoperative autotransfusion but, until efficiency is improved, it should only be used for cardiovascular surgery when excess heparin can be reversed with protamine. 相似文献
6.
7.
Streptococcus bovis bacteremia is known to be related to neoplastic lesions of the colon. We describe a patient with several complications of S bovis bacteremia and adenocarcinoma of the colon--endocarditis, spondylodiskitis, and splenic abscess. We believe this is the eighth known case of endocarditis and diskitis caused by S bovis and the third case of endocarditis and splenic abscess by S bovis in a patient with adenocarcinoma of the colon. 相似文献
8.
Schistosoma mansoni and S. japonicum infections in nude mice (nu/nu) were compared with infections in nu/+ heterozygotes or intact mice. Seven to 12 weeks after exposure to S. mansoni, the responses of Swiss NCR, C3H, BALB/c and C57B1/6 nude mice did not differ substantially. Nude mice of all these strains showed minute granulomas around eggs in the liver and minimal hepatic fibrosis. Microvesicular and necrotizing changes in hepatocytes were similar in all mouse strains, and S. mansoni infections were frequently lethal to nude, but not to intact mice between the seventh and ninth weeks of infection. Nude mice that survived the ninth week of infection generally lived until the 12th week. The number of eggs per mature worm pair in the tissues of S. mansoni-infected nude mice was similar to the number in intact mice, but nude mice passed fewer eggs in the feces. Nude mice that received serum from infected intact mice excreted eggs in the stool in numbers equivalent to intact mice, but continued to form minute granulomas around S. mansoni eggs. Reconstitution with fetal thymus or with splenocytes from normal or S. mansoni-infected mice partially or completely restored hepatic granuloma size, granuloma eosinophils, hepatic fibrosis, and excretion of eggs in the feces. In contrast to S. mansoni infection, S. japonicum infections in nude mice did not cause necrosis of hepatocytes or excessive mortality, and S. japonicum eggs were passed in the feces in numbers equivalent to those passed by infected intact mice. 相似文献
9.
José Vicente Calvano Antônio Carneiro de Mesquita Filho Vladimir Castro Alves Marcelo Soares Lubaszewski 《Microelectronics Journal》2002,33(10):823-834
This work presents a method for synthesizing testable continuous-time linear time-invariant electrical networks using 1st order blocks for the implementation of analog linear circuits. A functional-structural fault model for the block, and a fault dictionary are proposed together with a simple set of test vectors. The method allows, also, the fault grade evaluation for the modeled faults. The results obtained from the two application examples have shown the suitability of the approach as a design for test method for analog circuits. 相似文献
10.
T De Brito CR Carneiro MC Nakhle DM Lima CP Abrantes-Lemos M Sandoval AM Silva 《Canadian Metallurgical Quarterly》1998,6(4):368-376
Gene therapy has the potential to provide cancer treatments based on novel mechanisms of action with potentially low toxicities. This therapy may provide more effective control of loco-regional recurrence in diseases such as non-small cell lung cancer (NSCLC), as well as systemic control of micrometastases. Despite current limitations, retroviral and adenoviral vectors can in certain circumstances provide an effective means of delivering therapeutic genes to tumour cells. Although multiple genes are involved in the process of carcinogenesis, mutations of the p53 gene are the most frequent abnormality identified in human tumours. Pre-clinical studies both in vitro and in vivo have shown that restoration of p53 function can induce apoptosis in cancer cells. Phase I clinical trials now show that p53 gene replacement therapy is feasible and safe using both retroviral and adenoviral vectors, and that it induces tumour regression in patients with advanced NSCLC and recurrent head and neck cancer. Other pre-clinical studies indicate that gene therapy may have useful synergy with cytotoxic and radiation therapy. This paper describes the different gene therapy strategies under investigation and the pre-clinical data that provides a rationale for the gene replacement approach, reviews clinical trial data and presents novel ideas for improving current vectors and gene delivery to tumours. 相似文献