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71.
《Water research》1996,30(6):1377-1385
Biotransformation of chloroform (CF) was studied in a methanogenic environment utilizing acetic acid as the primary substrate. CF removal efficiency of more than 99% was achieved in a chemostat, fed constant acetic acid concentration (2510 mg/l) and different CF concentrations, up to 16.74 μM. Biological methane potential tests were conducted in serum bottles using the culture from the chemostat with an average biomass concentration of 53 mg/l. The culture exhibited a maximum rate of CF transformation of 0.26 μM/h corresponding to an initial CF concentration of 1.25 μM. At initial CF concentrations higher than 2.76 μM, the rate of CF transformation became constant at 0.06 μM/h. CF present at any concentration inhibited the utilization of acetic acid, and at CF concentrations equal to or exceeding 2.7 μM, the culture was completely inhibited and no acetic acid was utilized by the culture even after the CF was completely degraded. The culture transformed CF without the addition of acetic acid, but the addition of acetic acid considerably increased the rate of biotransformation. However, increase in acetic acid concentration beyond 50 mg/l did not increase the rate. The culture exhibited higher rates of CF biotransformation when it was acclimated with higher influent concentration of CF in a chemostat. Reductive dehalogenation was one of the pathways for the transformation of CF leading to the formation of dichloromethane which was also transformed by the culture. 相似文献
72.
《International Journal of Project Management》1988,6(3):148-151
The relationship of management to capital as resources invested in the productive process in construction is discussed. Capital and labour are shown to be interdependent in the process with management a catalyst facilitating their combination. A perspective of the labour-capital relationship emphasizing the benefits that can result from mutual understanding and respect is presented. 相似文献
73.
《Fire Safety Journal》1998,31(3):201-225
A significant contributing factor to wildland fire development is the slope effect which causes the fire spread rate to increase considerably as compared to horizontal spread. This leads to difficulties in determining the development of the fires hence in coordinating forest fighting efforts. In the present study, a two-dimensional non-stationary model for a fire spreading across a sloping fuel bed made up of Pinus pinaster litter is described. Based on a series of hypotheses, we first defined a medium equivalent to the pine needle litter for which we provided a thermal balance. By coupling this balance to a diffusion flame model we obtained the fire spread model numerically solved by means of the SIMPLEC procedure. The fire spread rates given by the simulations were then compared to experimental results generated by small-scale laboratory fires for a range of slope values. Predicted flow field structure, and temperature field are also discussed. 相似文献
74.
《Energy and Buildings》2004,36(5):415-422
The potential of controlling techniques for an electrochromic device is investigated in a systematic way, using both experimental and theoretical tools. Concerning the theoretical part a model was developed in the TRNSYS environment and validated against experimental data. These data were collected from experiments, which were carried out in a PASSYS test cell with a movable wall. Having established a good model performance several cases of window types (such as a 4 mm clear window and a low-e double glazing) and controlling strategies for the electrochromic device are simulated. Obtained results from the series of simulations were compared in terms of the heating and cooling loads of the test cell for each case. It was found that the development of a scheduled control strategy for the electrochromic glazing is better in terms of cooling loads. Finally, a more sophisticated control strategy was examined based on the adaptive fuzzy approach. 相似文献
75.
《Building and Environment》2004,39(10):1243-1251
Maintainability of building has been identified as one of the key areas in which the construction industry in Singapore must achieve significant improvement. However, maintainability is generally given little attention in many developing countries. This leads to financial losses in many respects to the client over the life of the building and inefficient use of the asset. This paper reports the results of a study that identified the key aspects that would enable and motivate Singapore's construction industry to achieve improvement in the level of maintainability of buildings. An industry wide survey was conducted and two key factors were identified, using factor analysis, which would enable Singapore's construction industry to enhance the level of maintainability in buildings. The two factors are developing knowledge on maintainability and setting a benchmark for maintainability. However, the reluctance of the different parties to assume further responsibilities and liabilities would create an obstacle to achieving such improvements. 相似文献
76.
Benthic diatom assemblages have been used to evaluate the water quality of two rivers subjected to marked human influences. These rivers, the Llobregat and the Ter, are located in N.E. Spain, and supply water for industrial, agricultural and urban requirements of roughly three million people. The diatom communities in the headwaters are similar in both rivers (Achnanthes minutissima, Cymbella ventricosa, Gomphonema anguslatum). Species of Navicula, Nitzschia and Gomphonema develop in the middle reaches of both rivers when not disrupted by extraneous factors. In the river Ter significant pollution modifies this community and Nitzschia palea, Nitzschia gandersheimiensis and Gomphonema parvulum appear as the most tolerant species. In the Llobregat, the pollution from the salt mine operations also modifies the diatom assemblage and Nitzschia frustulum, Surirella ovata, Navicula atomus are the most abundant species. Reservoirs in the river Ter improve the quality of water and a community of Fragilaria sp. pl. becomes dominant downstream. 相似文献
77.
The 6 day calcium EDTA lead excretion test was performed on German and Australian subjects with normal and impaired renal function, some of whom had gout, in order to determine if the pattern of results differed between the two countries. The German subjects lived around Heidelberg in an industrialized area where chronic lead nephropathy had not hitherto been thought to exist, while the Australian subjects were all from the State of Queensland where chronic lead nephropathy from the ingestion of lead paint during childhood continues to contribute to morbidity and mortality.Apart from the subjects with normal renal function, the German subjects consistently excreted less lead than the Queensland subjects and a strikingly consistent pattern was found: in both countries, subjects with a history of lead exposure, whether gouty or not, had greater EDTA lead excess values than subjects with gout but no lead exposure, these subjects in turn having greater EDTA lead excess values than subjects with neither gout nor lead exposure. In each country, the highest median EDTA lead excess occurred not in the group with gout and lead exposure, but in the group without gout and with lead exposure. 相似文献
78.
Biofilm morphology and mass are two of the important characteristics governing the kinetics of substrate removal by biofilms. Many previous studies showed only sparse biofilm on attaching media. However, one of the reasons which might cause a sparse-biofilm specimen in scanning electron microscopy (SEM) is that the treatment of a biofilm sample is harsh and can cause various artifacts. This study was conducted to evaluate the loss of biofilm during a conventional preparation procedure. Biofilm lost during preparation stages was collected on membrane filters. A different technique—the membrane filter method—was devised to carry a biofilm sample through the preparation stage with reduced losses. The sample was sandwiched between membrane filters during preparation so that the loss was minimized and the lost biofilm could be saved for qualitative and quantitative evaluations. SEM examination of biofilms and membrane filters showed that biofilm loss was much more significant with conventional treatment. 相似文献
79.
《Water research》1986,20(10):1315-1320
The effects of cyanide on the degradation of phenol, m-cresol, p-cresol, catechol and hydroquinone in acclimated methanogenic consortia were studied. Batch cultures with cyanide concentrations up to 10 mg l−1 were monitored for phenolic removal and methane production. Results showed that the methanogens were more sensitive to cyanide inhibition than the phenolic-degrading bacteria. The former group was inhibited by lower cyanide concentrations and took longer to adapt to the toxicant. Phenolic degradation was slowed to varying degrees depending upon the phenolic substrate. The addition of 400 mg l−1 acetate or 10−2 M bromoethanesulfonic acid, a specific inhibitor of methanogenesis, also slowed the rates of phenolic degradation. Thus cyanide can affect a phenolic-degrading consortium by causing an accumulation of endproducts of the non-methanogenic fermentation (e.g. acetate) because of the inability of the methanogens to consume them.A draw and feed culture adapted to phenol degradation in the presence of 5 mg l−1 cyanide was able to produce methane from feed solutions containing 5 mg l−1 cyanide and 250 mg l−1 phenol at the same rate as a control culture receiving 250 mg l−1 phenol but no cyanide. 相似文献
80.
The procedure adopted by the Standard Seawater Service for the calibration of Standard Seawater in electrical conductivity relative to a defined potassium chloride solution is described. 相似文献