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941.
942.
943.
PET高速纺丝方法及超高速纺丝纤维成形机理 总被引:1,自引:0,他引:1
综述了 PET高速纺丝热辊法生产工艺 (MG)、冷辊拉伸蒸汽定型法生产工艺 (H 4S)、热管法生产工艺 (TCS)、热管拉伸法生产工艺 (HCS)以及超高速纺丝工艺 (SHSS) ;阐明了超高速纺在纺程上结构的发展与成形机理 ,以及超高速纺纺程上的细颈现象 ,超高速纺的成形机理与高速纺是不同的 ,明显区别在于细颈点的出现 相似文献
944.
Shuh-Jeng Liaw Shiao-Hung Chiang George E. Klinzing 《Chemical Engineering Communications》1992,117(1):73-84
A hydrogen probe made of nickel tubing has been used to monitor the release of hydrogen from coal liquid solvents at elevated temperatures and pressures. A knowledge of this release rate is helpful in determining the overall hydrogen balance for coal liquefaction operations, in choosing among alternative solvents and in evaluating the validity of model compounds. The hydrogen release was found for coal liquids to reach a constant value when the reactor temperature was steady. In the case of some model compounds the amount of hydrogen released continued to increase and equilibrium was not attained during a 10 hours measurement period. For the coal liquids the total pressure of the system was found to increase sharply with time indicating the production of gases other than hydrogen, while for the model compounds the total pressure increases were almost parallel to the increases of the hydrogen partial pressure. A correlation was developed for the percentage of hydrogen released with the aromatic fraction distribution in the coal liquids. The hydrogen probe was a valuable instrument for continuously following the hydrogen changes in these dehydrogenation experiments. 相似文献
945.
T. Okano J. Tanabe M. Fukuda M. Tanaka 《Journal of the American Oil Chemists' Society》1992,69(1):44-46
The surface-active properties and emulsification ability of sodium α-sulfonated fatty acid esters, CmH2m+1CH-(SO3Na)COOCnH2n+1, were studied as a function of the hydrophobic alkyl chainlength in the fatty acid (m=8−16) and the alcohol (n=8−18). As
a result, it was discovered that sodium α-sulfonated fatty acid esters have a structural effect on the Krafft point different
from that of amphiphiles with short alkyl chains. Moreover, some of the α-sulfonated fatty acid esters have quite low interfacial
tensions, as well as non-foaming properties, which depend upon the total (m+n) number of carbon atoms in the alkyl chains. 相似文献
946.
J. H. M. Scholten 《Nutrient Cycling in Agroecosystems》1992,33(2):107-114
To increase the fertilizer-N efficiency in lowland rice (Oryza sativa L.) cultivation, new management practices are needed. Main cause of the present low efficiency is the low N recovery by plants, as a considerable part of the N applied is lost; deep placement techniques improve the recovery. A pneumatic injector, with which urea prills can be point-placed at a depth of 5–10 cm in paddy soils, was tested in 38 on-farm trials in 1989/90, mostly during the wet season. The experiments, located in Africa and Asia, focussed on differences in grain yield between conventional methods of broadcasting urea and injection by the pneumatic injector, at recommended N-rates. The study shows that the pneumatic injector is effective as a tool to improve the N fertilizer efficiency. The average yield increases per region, resulting from the use of the injector, ranged from about 250 to 1300 kg grain ha–1. The value of the yield increase would allow most farmers to recover the costs of the injector within one season, even if labour was hired to carry out the injections. The average labour requirement of the injector was 40 hours ha–1. In Indonesia, injection of prilled urea gave yields similar to those obtained with urea briquettes. 相似文献
947.
Spherical bulb fibre optic probes, developed and applied for bubble characterization in a bubble column and a slurry bubble column at high temperature, were investigated. The principle of operation of these new optical fibre probes is based on the difference in refractive indices between the gas and the liquid phases. The interaction between the gas bubbles and the fibre optic probes in a bubble column was studied using photographic techniques. The first objective of these experiments was to study the response of the sensors upon contact with gas bubbles of various sizes. The second objective of this study was to establish, under controlled situations, the optical probe bubble detection performance and ability for local quantitative measurements of the bubble rise velocity and the gas hold-up. 相似文献
948.
A one-dimensional steady-state mathematical model has been developed to simulate the process of calcination of petroleum coke in a rotary kiln. A simulation is made to reproduce the operating conditions prevailing during a normal working day, in order to validate the model, and to study the effects of the main process control variables. It has been found that of the energy provided by combustion, 59.5 % comes from hydrogen, 14.6 % from the carbon of the coke bed, 13.8 % from coke dust, 11.3 % from methane and 0.8 % from tar. A comparison with existing models is made to identify eventual similarities between the various kilns under study. It appears that maximum coke temperature occurs at 45 to 55 % of kiln length, while volatile matters evolution takes place between 5 and 60 % of kiln length, measured from feed end. 相似文献
949.
A. G. Rigas 《时间序列分析杂志》1992,13(5):441-450
Abstract. In this paper we consider techniques of spectral analysis for stationary point processes in order to study the behaviour of a complex physiological system. The estimates of the power spectrum are obtained by smoothing the periodogram which is computed very rapidly with the help of the fast Fourier transform algorithm. In the computation of the estimates we can use either the whole record of the data or a number of disjoint records. 相似文献
950.
配煤线性规划模型的研究 总被引:9,自引:0,他引:9
陈晓玲 《煤炭加工与综合利用》2003,(2):34-38
通过对配煤主要指标的理论分析和煤质实验结果的验证 ,得出了配煤的分析基灰分、水分、挥发分、硫分、固定碳、发热量、灰熔融温度都具有线性可加性的结论 ,并由此建立了配煤的线性规划模型 相似文献