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971.
N. Sehat M. P. Yurawecz J. A. G. Roach M. M. Mossoba K. Eulitz E. P. Mazzola Y. Ku 《Journal of the American Oil Chemists' Society》1998,75(10):1313-1319
The objective of this study was to identify autoxidation products of methyl 9,12-epoxyoctadeca-9,11-dienoate (F9,12). Previous work has shown that F9,12 is a product both of autoxidation and singlet oxygen oxidation of the methyl ester derivative of conjugated linoleic acid
(CLA). F9,12, 95% pure, was synthesized from methyl ricinoleate. The synthetic F9,12 was heated at 50°C in sealed tubes containing air. Each tube contained 6 mg F9,12 and 1 mg methyl stearate as an internal standard. Samples were taken at 4.5, 7, 23, 46.5, 69.5, and 93 h. The oxidized F9,12 was dissolved in isooctane and analyzed by gas chromatography (GC), GC-direct deposition-Fourier transform infrared spectroscopy,
and GC-electron ionization mass spectrometry. CLA methyl ester was oxidized in a similar manner. Under these conditions, the
half-lives of CLA and F9,12 were 40 and 35 h, respectively. Oxidation products of F9,12 that were identified included: 5-hexyl-2-furaldehyde (I), methyl 8-oxooctanoate (II), methyl 13-oxo-9,12-epoxytrideca-9,11-dienoate (III), methyl 8-oxo-9,12-epoxy-9,11-octadecadienoate (IV), and methyl 13-oxo-9,12-epoxy-9,11-octadecadienoate (V). 相似文献
972.
973.
Sung Ku Kwon Kwang Ho Kwon Byung Whan Kim Jong Moon Park Seong Wook Yoo Kun Sik Park Yoon Kyu Bae Bo Woo Kim 《ETRI Journal》2002,24(3):211-220
This study characterizes an oxide etching process in a magnetically enhanced reactive ion etching (MERIE) reactor with a CHF3/CF4 gas chemistry. We use a statistical 24‐1 experimental design plus one center point to characterize the relationships between the process factors and etch responses. The factors that we varied in the design include RF power, pressure, and gas composition, and the modeled etch responses were the etch rate, etch selectivity to TiN, and uniformity. The developed models produced 3D response plots. Etching of SiO2 mainly depends on F density and ion bombardment. SiO2 etch selectivity to TiN sensitively depends on the F density in the plasma and the effects of ion bombardment. The process conditions for a high etch selectivity are a 0.3 to 0.5 CF4 flow ratio and a –600 V to –650 V DC bias voltage according to the process pressure in our experiment. Etching uniformity was improved with an increase in the CF4 flow ratio in the gas mixture, an increase in the source power, and a higher pressure. Our characterization of via etching in a CHF3/CF4 MERIE using neural networks was successful, economical, and effective. The results provide highly valuable information about etching mechanisms and optimum etching conditions. 相似文献
974.
Ching-Heng Ku Wen-Hsiang Tsai 《Industrial Electronics, IEEE Transactions on》2001,48(1):205-215
An obstacle avoidance method for use in person following for vision-based autonomous land vehicle (ALV) guidance is proposed. This method is based on the use of vehicle location estimation and a quadratic pattern classifier, and aims to guide the ALV to follow a walking person in front by navigating along a derived collision-free path. Before generating the collision-free path, the person's location is obtained from extracted objects in the image by a person detection method. The object closest to a predicted person location is regarded as the followed person and the remaining objects are regarded as obstacles. The collision-free navigation path is designed for ALV guidance in such a way that the ALV not only can keep following the person but also can avoid collision with nearby obstacles. The navigation path results from a quadratic classifier that uses the vehicle and all of the objects in the image as input patterns. A turn angle is then computed to drive the ALV to follow the navigation path. Successful navigation sessions confirm the feasibility of the approach 相似文献
975.
Flue gas properties are very important for evaluation of a boiler’s performance. Non-homogeneity of the properties and large dimensions of flue-gas ducts require measurements with large number of measuring points to provide high accuracy of measurement results. An analysis of simpler measuring methods is presented. It is shown that high accuracy can be achieved with small number of measuring points if their positions are optimised with respect to pre-determined conditions in the flue gas duct. The methods can be used as operational measurements to monitor boiler’s performance and for on-line calculation of boiler’s efficiency. 相似文献
976.
Photocatalytic decomposition of benzene in an air stream in a continuous TiO2-coated optical fiber photoreactor (OFP) was demonstrated to be effective at relatively short retention times. An increase
in TiO2 coating thickness, fiber length and retention time improved the decomposition of benzene; however, excessive TiO2 coating thickness and optical fiber length may hamper the reaction. The UV light intensity distribution on and within the
optical fiber was modeled using Snell’s law and UV light energy balance. The modeled profile indicated that the UV light intensity
decreased rapidly along the axial and radial directions of the optical fiber. A mathematical model combining the continuity
equations and Langmuir–Hinshelwood surface kinetics was established to adequately describe the reaction behavior of benzene
decomposition in the OFP with only single TiO2-coated fiber. 相似文献
977.
R.A. Bia?ecki T. Burczyński W. Ku? 《Computer Methods in Applied Mechanics and Engineering》2005,194(17):1839-1859
Shape optimization of heat conducting, elastic bodies subjected to thermal and standard loads is considered. Interaction of stress and temperature fields is modelled using the formulation of steady state thermoelasticity. The presence of heat radiation with mutual irradiation of the boundaries and the presence of shadow zones is taken into account. Evolutionary algorithm is used to evaluate the optimal shape. The boundary element method is applied to discretize the thermoelasticity, conduction and radiation problems. 相似文献
978.
979.
Inhibition of telomerase activity by PKC inhibitors in human nasopharyngeal cancer cells in culture 总被引:2,自引:0,他引:2
Telomerase is a specialized ribonucleoprotein polymerase that adds hexanucleotides (TTAGGG) onto human chromosomal ends. The expression of telomerase activity has been associated with cell immortalization and the malignant phenotype in most cancers. How the telomerase activity is regulated in cancer cells is presently not known. In this work, the effects of cell cycle blockers, DNA damaging agents, TopII inhibitors and proteins kinase inhibitors on the telomerase activity were examined in cultured nasopharyngeal carcinoma cells NPC-076. Agents which interfere with tubulin assembly (Taxol and vinblastine) and agents which arrest cells at S phase (methotrexate and 5-fluorouracil) did not inhibit telomerase activity of treated cells. Agents which damage DNA (cisplatin, methyl methanesulfonate, and UV radiation) and TopII inhibitors (etoposide and daunorubicin) also did not inhibit telomerase activity of treated cells. Among the protein kinase inhibitors examined, no significant inhibition of telomerase activity was observed with cells treated with quercetin, H-89, or herbimycin A. On the other hand, two protein kinase C (PKC) inhibitors (bisindolylmaleimide I and H-7) were found to produce a big inhibition of telomerase activity in treated cells. Staurosporine produced a moderate inhibition, and sphingosine had a small inhibitory effect. The inhibition of telomerase activity by PKC inhibitors appears to be specific since the treated cells were mostly viable (i.e., greater than 75%) and still retained significant levels of protein synthesis capability. These results implicate that protein kinase C is involved in the regulation of telomerase activity in vivo. 相似文献
980.
Adaptive recovery of a chirped signal using the RLS algorithm 总被引:1,自引:0,他引:1
This paper studies the performance of the recursive least squares (RLS) algorithm in the presence of a general chirped signal and additive white noise. The chirped signal, which is a moving average (MA) signal deterministically shifted in frequency at rate ψ, can be used to model a frequency shift in a received signal. General expressions for the optimum Wiener-Hopf coefficients, one-step recovery and estimation errors, noise and lag misadjustments, and the optimum adaptation constant (βopt) are found in terms of the parameters of the stationary MA signal. The output misadjustment is shown to be composed of a noise (ξ0Mβ/2) and lag term (κ/(β2ψ2)), and the optimum adaptation constant is proportional to the chirp rate as ψ2/3 . The special case of a chirped first-order autoregressive (AR1) process with correlation (α) is used to illustrate the effect the bandwidth (1/α) of the chirped signal on the adaptation parameters. It is shown that unlike for the chirped tone, where the βopt increases with the filter length (M), the adaptation constant reaches a maximum for M near the inverse of the signal correlation (1/α). Furthermore, there is an optimum filter length for tracking the chirped signal and this length is less than (1/α) 相似文献