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In the indoor visible light transmission environment with complex noise, traditional received signal strength indication(RSSI)localization algorithm and imaging localization algorithm are unable to accurately determine the reason of the inaccurate localization model and inadequate constraints of position coordinates. In order to solve the problems, a visible light localization algorithm based on multi-measurements constraints is presented in the paper. The algorithm first constructs a joint localization state space model based on RSSI localization and the imaging localization algorithm. Then, states, measurements and their equations are constructed based on the space model. Finally, the equations are resolved using the unscented Kalman filter(UKF). Compared with RSSI localization and imaging localization, simulation results show that the RMSE of the proposed algorithm could be closer to the Cramer Rao bound. Besides, the localization probability of the proposed algorithm is higher than that of RSSI localization and imaging localization algorithm. 相似文献
73.
Characterisation of n-type GaAs, etched in a 5:1:1 mixture of H2SO4:H2O2:H2O, was performed using X-ray photoelectron spectroscopy (XPS) and electrochemical AC impedance. Quantitative XPS analysis of GaAs indicated that the as-received wafers had a gallium-rich native oxide which was not affected by solvent degreasing treatments. Subsequent, oxidative etching formed a thinner arsenic-rich oxide. It is suggested that etching causes initial thinning of the native oxide; subsequently, transport of Ga and As ions occurs through the film by high-field ionic conduction. Arsenic enrichment in the resultant oxide film arises from the greater mobility of Ga3+ ions compared with As3+ ions as well as the relative solubility of Ga2O3 compared with As2O3. The as-received oxide film thickness, determined from the ratio of the oxide to substrate XPS peaks, was approximately 1.1 nm. After etching this was reduced to about 0.7 nm. This thickness is consistent with the driving voltage for oxide formation being provided by the electrochemical potential difference between hydrogen peroxide and the GaAs wafer (i.e. between 0.4 V, for As, and 1.2 V, for Ga, at a nm V−1 ratio of 2). Capacitance measurements, derived from electrochemical impedance data, combined with film thickness data, gave a value of about 5 for the dielectric constant of As2O3. 相似文献
74.
用能量为50keV,剂量为3×10~(17)ions/cm_2的B~+注入多晶Ni,通过力学性能实验研究了多晶Ni注入前后表面硬度和疲劳性能的变化,以及多晶Ni表面层注入和疲劳前后化学成分、滑移特征、裂纹萌生、断裂方式和微观结构的变化。结果表明,B~+注入多晶Ni后,表面区域形成一个不同组织结构的由Ni-B非晶、Ni_3B和Ni_4B_3第二相以及辐照损伤组成的多层次的注入层,提高了多晶Ni的表面硬度,并使其疲劳极限提高16%。探讨了B~+注入影响多晶Ni疲劳极限的几种可能机制。 相似文献
75.
The pressing bonding of steel plate to QTi3.5-3.5graphite slurry was studied. The bonding conditions were 620℃ for preheating temperature of steel plate, 530℃ for preheating temperature of dies, 50 MPa for pressure and 2 min for pressing time. The relationship between the solid fraction of QTi3.5-3.5graphite slurry and the interracial mechanical property of bonding plate was obtained. The results show that when the solid fraction of QTi3.5-3.5graphite slurry is smaller than 45.8%, the interracial shear strength of bonding plate increases with the increasing of solid fraction. When the solid fraction is larger than 45.8%, the interracial shear strength decreases with the increasing of solid fraction. When the solid fraction is 45.8%, the largest interracial shear strength of bonding plate 127 MPa can be got, and the interface is made up of Fe-Cu solid solution. 相似文献
76.
38CrSi钢表面纳米结构层力学性能的研究 总被引:1,自引:1,他引:1
采用超音速微粒轰击技术在38CrSi合金钢表面制备了厚度约为25μm纳米晶层.利用X射线衍射、扫描电镜和透射电镜对表面结构进行分析.纳米结构层的最表面层的晶粒尺寸约为16nm,晶粒尺寸随着距表面距离的增加而增大.利用纳米压痕仪对表面纳米结构层的力学性能进行研究,结果表明,当表面晶粒尺寸降低到纳米量级时力学性能明显改善,最表面纳米结构层的硬度是基体的2倍左右,并服从Hall-Petch关系;表面纳米结构层的弹性恢复系数明显提高;利用该方法制备的纳米晶对弹性模量的影响较小;对表面纳米化样品进行低温退火处理可使纳米结构层的性能更加稳定.分析表明表面纳米结构层力学性能的改善主要是表面晶粒细化的结果. 相似文献
77.
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79.
The carcinogen N-nitrosodimethylamine (NDMA) may be quantitated routinely at ultratrace (ng/L) levels in drinking water or contaminated groundwater. The aqueous sample is passed through a preconditioned Empore C18 filter disk to remove neutral nonpolar species and then extracted continuously overnight with highest purity dichloromethane. The latter is then concentrated to 1 mL, and a large aliquot (up to 200 microL) is loaded onto a dual-stage carbon sorbent trap, after which the solvent is removed with ultrapure helium. The concentrated residues are then injected onto a gas chromatographic column using a short-path thermal desorber. NDMA is selectively detected using a chemiluminescent nitrogen detector (CLND) operated in its nitrosamine-selective mode. The reporting limit for this procedure, evaluated using two independent statistically unbiased protocols, is 2 ng of NDMA/L. A related procedure, employing an automatic sampler instead of the short-path thermal desorber, provides convenient analysis of heavily contaminated samples and exhibits a reporting limit (same protocols cited previously) of 110 ng of NDMA/L. When the two methods are used together in a "two-tiered" protocol, NDMA concentrations spanning 4 orders of magnitude (ng/L to microgram/L levels) may be measured routinely. The low-level procedure employing only the short-path thermal desorber was applied successfully to three sources of drinking water, where NDMA concentrations ranged between 2 and 10 ng of NDMA/L. The two-tiered protocol was applied to a series of contaminated groundwaters whose NMDA concentrations ranged between approximately 10-7000 ng of NDMA/L. The results agreed with those obtained from an independent collaborating laboratory, which used a different analytical procedure. 相似文献
80.
The indirect estimation of thiamine levels in human blood by measuring thiamine pyrophosphate effect on erythrocyte transketolase activity is the method of choice in most clinical laboratories. We describe here an optimized, time-saving, and accurate method to determine the thiamine pyrophosphate effect in as many as 16 blood samples simultaneously. The method is based on a multi-point determination using a computer remote-controlled microplate reader. For multiple sample handling, three pooled reaction mixtures are freshly prepared and loaded onto a 96 well microtitre plate. A pre-written software is then initiated to remote-control the system. The data is retrieved and processed to calculate thiamine pyrophosphate effect by a self-written "macro" on a "Quattro-Pro" worksheet database. This method proves to be highly accurate (coefficient of variance: 2.7%), reproducible (coefficient of variance: 4.1%) and economical. 相似文献