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101.
102.
Feng Rao Zhitang SongYan Cheng Mengjiao XiaKun Ren Liangcai WuBo Liu Songlin Feng 《Acta Materialia》2012,60(1):323-328
Upon phase transition, the resistivity changes of Ge2Sb2Te5 (GST) and Si3.5Sb2Te3 (SST) are proved to be closely related to the variations of band gap and density of localized states. Amorphous SST has a slightly more localized state than amorphous GST; however, the larger band gap of SST material causes relatively difficult phase transition processes. Therefore, the phase change memory (PCM) cell based on the SST film shows larger threshold voltages for both set and reset operations than that of the GST-based PCM cell. The formation of amorphous Si-rich segregated areas in the SST film during phase transitions increases the randomness of the whole film microstructure, which leads to a different Urbach tail absorption result to that of the GST film. 相似文献
103.
目的高功率红外激光进行铜构件加工时,激光吸收率低是阻碍其工业加工、影响加工质量的重要因素,因此拟通过皮秒激光织构预处理工艺,将铜表面红外激光吸收率从低于10%提高至70%以上。方法从改变铜表面特性着手,利用精密微细加工系统进行凹槽织构处理,通过共聚焦显微镜和扫描电镜对20%~50%激光功率、20~90次扫描次数下的织构特征进行分析,通过反射率检测仪对不同织构下铜表面的红外激光吸收率进行测试。结果相比原始铜板,织构后铜表面红外激光吸收率有了大幅提高,且十字凹槽织构工艺下的吸收率高于同参数下的平行凹槽织构。在30%激光功率、60次扫描次数的工艺下,形成深度44mm、间距50mm、表面粗糙度12.15mm、倾角75°的十字凹槽织构,铜表面红外激光吸收率达86.75%。结论织构深度、表面粗糙度、氧化物是影响吸收率的重要因素,经过"周期性微米级织构-相爆炸喷溅颗粒物-形成黑色CuO层"三个过程,对应"光自陷织构-表面喷溅颗粒物-CuO层"三步吸收,织构工艺能够将铜表面红外激光吸收率提高近9倍。 相似文献
104.
《稀有金属材料与工程》2012,(Z1):168-171
A diesel engine crankshaft is failed in journal and the dominant failure mechanism is wear.A 6R robot-based automatic high velocity arc spraying system was developed in this study.The remanufacturing process of engine crankshaft was designed based on the newly developed automatic spraying system and the FeAlNbB cored wire.The two spraying way planning were designed.The results of industrial application in miniature show that,both of the main shaft journal and the crank journal of the crankshaft can be deposited of coating in only one procedure using the developed automatic spraying technology,and a reliable quality remanufactured part was obtained.A comparative evaluation shows that the improvement process offers several benefits.Such as,the coating bond strength and spray rates are all highly increased;the remanufactured cost and time are decreased.Furthermore,this technology has several advantages such as energy and material saving,and environmental protecting,a wide application foreground for this technology is therefore performed. 相似文献
105.
Influence of temperature on photoconductivity of single Se nanowires has been studied. Time response of photocurrent at both room temperature and low temperature suggests that the trap states play an important role in the photoelectrical process. Further investigations about light intensity dependence on photocurrent at different temperatures reveal that the trap states significantly affect the carrier generation and recombination. This work may be valuable for improving the device optoelectronic performances by understanding the photoelectrical properties. 相似文献
106.
107.
Z. vandov J. Marko
. Jelemenský 《Chemical engineering journal (Lausanne, Switzerland : 1996)》2008,140(1-3):381-390
A significant part of the safety analysis of a reactive distillation column is the identification of multiple steady states and their stability. A reliable prediction of multiple steady states in a reactive distillation column is influenced by the selection of an adequate mathematical model.For modelling reactive distillation columns, equilibrium (EQ) and nonequilibrium (NEQ) models are available in the literature. The accuracy of the nonequilibrium stage model seems to be limited mainly by the accuracy of the correlations used to estimate the mass transfer coefficient and interfacial area.The binary mass transfer coefficients obtained from empirical correlations are functions of the tray design and layout, or of the packing type and size, as well as of the operational conditions and physical properties of the vapour and liquid mixtures.In this contribution, the nonequilibrium model was used for the simulation of a reactive distillation column. For prediction of the binary mass transfer coefficient for a sieve tray, four correlations were chosen to show their impact on the prediction of the reactive distillation column behaviour. As a model reactive distillation system, the synthesis of methyl tertiary-butyl ether (MTBE) was chosen. The steady-state analysis and the dynamic simulation of the model system were done. Qualitative differences between the steady states were predicted using the chosen correlations. 相似文献
108.
Mohammad Mehdi Papari Jalil Moghadasi Soodabeh Nikmanesh Mahmood Reza Dehghan 《中国化学工程学报》2010,18(2):297-305
In our previous work, we calculated transport properties of pure gaseous polyatomic carbon tetrafluoride (CF4) and five equimolar binary gas mixtures of CF4 with noble gases through inversion technique. The present work is a continuation of our studies on determining the transport properties of binary gas mixtures CF4 with some gases including three diatomic molecules CO, N2, and O2, a linear polyatomic CO2, and two non-linear polyatomic molecules SF6 and CH4. The Chapman-Enskog and Vesovic-Wakeham methods as well as inversion procedure are used to determine the viscosities, diffusivities, and thermal conductivities, which deviates from the literature values within 1%, 4%, and 5%, respectively. 相似文献
109.
110.
Dick R 《Nanoscale research letters》2010,5(10):1546-1554
We consider electrons in the presence of interfaces with different effective electron mass, and electromagnetic fields in the presence of a high-permittivity interface in bulk material. The equations of motion for these dimensionally hybrid systems yield analytic expressions for Green’s functions and electromagnetic potentials that interpolate between the two-dimensional logarithmic potential at short distance, and the three-dimensional r −1 potential at large distance. This also yields results for electron densities of states which interpolate between the well-known two-dimensional and three-dimensional formulas. The transition length scales for interfaces of thickness L are found to be of order Lm/2m * for an interface in which electrons move with effective mass m *, and Le*/2eLepsilon_ast/2epsilon for a dielectric thin film with permittivity e*epsilon_ast in a bulk of permittivity eepsilon. We can easily test the merits of the formalism by comparing the calculated electromagnetic potential with the infinite series solutions from image charges. This confirms that the dimensionally hybrid models are excellent approximations for distances r ≳ L/2. 相似文献