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971.
In this paper, we propose a computational framework to incorporate regularization terms used in regularity based variational methods into least squares based methods. In the regularity based variational approach, the image is a result of the competition between the fidelity term and a regularity term, while in the least squares based approach the image is computed as a minimizer to a constrained least squares problem. The total variation minimizing denoising scheme is an exemplary scheme of the former approach with the total variation term as the regularity term, while the moving least squares method is an exemplary scheme of the latter approach. Both approaches have appeared in the literature of image processing independently. By putting schemes from both approaches into a single framework, the resulting scheme benefits from the advantageous properties of both parties. As an example, in this paper, we propose a new denoising scheme, where the total variation minimizing term is adopted by the moving least squares method. The proposed scheme is based on splitting methods, since they make it possible to express the minimization problem as a linear system. In this paper, we employed the split Bregman scheme for its simplicity. The resulting denoising scheme overcomes the drawbacks of both schemes, i.e., the staircase artifact in the total variation minimizing based denoising and the noisy artifact in the moving least squares based denoising method. The proposed computational framework can be utilized to put various combinations of both approaches with different properties together. 相似文献
972.
Adsorption and desorption of hydrogen and coadsorption of H2 with H2O and CO over Ru(00l) surface have been studied under UHV conditions using the technique of TDS. Surface hydrogen interacts
with adsorbed water resulting in an additional desorption state at 510 K which is not easily displaced by CO, but the total
number of adsorption sites for hydrogen adsorption is independent of the amount of H2O predosed at room temperature. Hydrogen adsorption is blocked easily by CO dose (more than 0.5 L) or a small amount of O(a)
formed from dissociative adsorption of water, and adsorbed hydrogen formed in the absence of significant water is easily displaced
by CO dose at even room temperature. 相似文献
973.
Fault identification for process monitoring using kernel principal component analysis 总被引:2,自引:0,他引:2
In this research, we develop a new fault identification method for kernel principal component analysis (kernel PCA). Although it has been proved that kernel PCA is superior to linear PCA for fault detection, the fault identification method theoretically derived from the kernel PCA has not been found anywhere. Using the gradient of kernel function, we define two new statistics which represent the contribution of each variable to the monitoring statistics, Hotelling's T2and squared prediction error (SPE) of kernel PCA, respectively. The proposed statistics which have similar concept to contributions in linear PCA are directly derived from the mathematical formulation of kernel PCA and thus they are straightforward to understand. The main contribution of this work is that we firstly suggest a fault identification method especially applicable to process monitoring using kernel PCA. To demonstrate the performance, the proposed method is applied to two simulated processes, one is a simple nonlinear process and the other is a non-isothermal CSTR process. The simulation results show that the proposed method effectively identifies the source of various types of faults. 相似文献
974.
In a previous article [1] theoretical predictions of velocity distributions, pressure drops and mean Nusselt-numbers are given for non-isothermal pipe flow of power-law fluids having a temperature dependent consistency-index. In the present investigation these solutions are checked for Newtonian fluids with extensive experimental data.A flow visualization technique was used for measuring the non-isothermal, laminar velocity profiles of glycerol in a round tube. Furthermore, accurate pressure drop measurements were carried out for non-isothermal tube flow of a viscous. Newtonian liquid. Finally logarithmic mean heat transfer coefficients were measured in laminar flow heat transfer.The experimental velocity profiles, pressure drops and heat transfer coefficients show a good agreement with those predicted theoretically. 相似文献
975.
Jong Suk Lee Yoon Sung Nam Byung‐Young Kang Sang‐Hoon Han Ih‐Seop Chang 《应用聚合物科学杂志》2004,92(1):517-522
To stabilize vitamin A in a cosmetic/dermatological formulation, we present here a new encapsulation method based on polymer microspheres having a localized “proton‐buffering” capacity. Poly(methyl methacrylate)‐g‐polyethylenimine (PMMA‐g‐PEI) was prepared by direct condensation grafting of PEI onto poly(methyl methacrylate‐co‐methyl acrylic acid). The reaction was confirmed by FT‐IR analysis showing the amide vibration at 1,550 cm?1. Elemental analysis indicated that the weight content of the grafted PEI was 1.6% (w/w). Vitamin A was encapsulated into PMMA‐g‐PEI microspheres by using an oil‐in‐water (O/W) single emulsion method. The presence of PEI moiety dramatically improved the chemical stability of vitamin A in microspheres. Vitamin A encapsulated within PMMA‐g‐PEI microspheres maintained 91% of its initial activity after 30‐day incubation at 40°C, while only maintaining 60% within plain PMMA microspheres. This study demonstrates that proton‐buffering within hydrophobic polymer matrix is a useful strategy for stabilizing “acid‐labile” active ingredients. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 517–522, 2004 相似文献
976.
β-SiC powder containing 6 wt% A12 O3 and 4 wt% Y2 O3 as sintering additives was pressureless sintered at 2000°C for 1 h (AYE-SiC) and 3 h (AYP-SiC). AYE-SiC consisted of an equiaxed grain structure and AYP-SiC exhibited a micro-structure with platelike grains as a result of grain growth related to β→α phase transformation during sintering, R -curve behavior and flaw tolerance for these silicon carbides were evaluated by the indentation-strength technique. For comparison, the R -curve behavior of conventional sintered, boron- and carbon-doped SiC (SS-SiC) was evaluated. AYE-SiC and AYP-SiC exhibited rising R -curve behavior with toughening exponents of m = 0.042 and m = 0.135, respectively. AYP-SiC exhibited better flaw tolerance and more sharply rising R -curve behavior than AYE-SiC. The more sharply rising R -curve behavior and the better flaw tolerance of AYP-SiC were attributed mainly to grain bridging of crack faces by platelike grains. Because of the high degree of transgranular fracture, SS-SiC exhibited a flat R -curve despite a microstructural feature with platelike grains. 相似文献
977.
The binary lanthanide catalyst for 1,3‐butadiene was invented for 40 years ago. However, it has not been employed in commercial application due to its poor solubility and low activity. Nanosized neodymium chloride (NdCl3) was prepared in tetrahydrofuran (THF) medium through dissolution, chelation, and colloidal formation steps. Anhydrous NdCl3 was dissolved in THF, and ca. 1.5 THF molecules were coordinated. In the colloidal formation step, THF was slowly replaced with the addition of cyclohexane, and pale blue nuclei, nanosize below 200 nm, were formed. The structural studies for NdCl3 · xTHF using X‐ray powder diffraction (XRD) and scanning electron microscope (SEM) indicate that high ordered crystallinity is decreased with reduced particle size from trigonal prismatic to porous sphere structure. Nano NdCl3, obtained as colloidal state in cyclohexane, was activated with Al(iBu)3 and Al(iBu)2H at room temperature and employed for 1,3‐butadiene solution polymerization. The nanosized Nd catalysts showed high activity (1.0 ~ 1.3 × 105 g/Nd mol · h), which is comparable to that of the ternary neodymium catalyst Nd(neodecanoate)3/AlEt2Cl/Al(iBu)3. The microstructures of polybutadiene, cis, trans, and vinyl, are about 96.0, 3.5, and 0.5%, respectively. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1279–1283, 2005 相似文献
978.
Novel positive‐working aqueous‐base developable photosensitive polyimide (PSPI) precursors based on partially diazonaphthoquinone (DNQ)‐capped polyamic esters bearing phenolic hydroxyl groups and a DNQ photosensitive compound (PIC‐3) were developed. The partially DNQ capped polyamic esters were prepared from an esterification reaction of 1,2‐naphthoquinone diazide‐5‐sulfonyl chloride with the polyamic esters. The partially DNQ capped polyamic esters decreased the dark film loss effectively in the aqueous‐base developer and were able to make thicker film resists compared to the uncapped polyamic esters. The 25 mol % DNQ‐capped BisAPAF–PMDA polyamic ester and BisAPAF–ODPA polyamic ester containing 25 wt % PIC‐3 photosensitive compound showed a sensitivity of 176 and 185 mJ/cm2, and a contrast of 1.68 and 1.02, respectively, in a 3‐μm film with 1.25 wt % tetramethylammonium hydroxide developer. A pattern with a resolution of 5 μm was obtained from both PSPI precursor compositions. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2293–2300, 2003 相似文献
979.
A pilot-scale sludge treatment plant was built to investigate the feasibility of ozonation processes for waste activated sludge treatment. Ozonation of wastewater sludge resulted in mass reduction by mineralization as well as by supernatant and filtrate recycle. Another advantage of sludge ozonation is a significant improvement of settleability and dewaterability. Experimental results showed that mass reduction of 70% and volume reduction of 85% compared with the control sludge was achieved through the sludge ozonation at a dose of 0.5?gO3/gDS. It is also interesting to note that the filterability deteriorates up to ozone dose of 0.2?gO3/gDS and then improves considerably at a higher ozone dose. The filterability could be improved by chemical conditioning even at a low ozone dose. The economic feasibility by cost analysis reveals that ozonation processes can be more economical than other alternative processes for sludge treatment and disposal at small-sized wastewater treatment plants. 相似文献
980.
The onset of thermal convection in a translucent porous layer is considered. Attention is focused on the effect of radiative heat transfer on the critical Rayleigh-Darcy number and the convection cell shape. If we consider the contribution of radiative heat transfer, the basic temperature profile is non-linear and the thermal convective instability is influenced by the ratio of conduction to radiation heat flux, the temperatures at the boundary surfaces, and radiative parameters such as wall emissivity, scattering albedo and extinction coefficient as well as the usual Rayleigh-Darcy number. Effects of these parameters on the onset of convective instability are investigated with the help of linear stability theory employing the Darcy's law and the radiative transport equation simplified by the P1 approximation. The increased effective thermal conductivity due lo the radiation inhibits the onset of convection and causes increased critical Rayleigh-Darcy number and decreased convection cell size. The results of the present work may be exploited to find out the optimal diameter of aerogel pellets and the air pressure in the double pane window filled with the translucent silica aerogel granules to suppress natural convection. 相似文献