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991.
We have carried out detailed investigations on the light absorption mechanism in single crystalline silicon (c-Si) (core)/amorphous Si (a-Si) (shell) coaxial nanowires (NWs). Based on the Lorenz-Mie light scattering theory, we have found that the light absorption in the coaxial NWs relies on the leaky mode resonances and that the light absorption can be optimized towards photovoltaic applications when the a-Si shell thickness is about twice the c-Si core radius. The photocurrent has been found to be enhanced up to ~ 560% compared to c-Si NWs, and to be further enhanced up to ~ 60% by coating the nonabsorbing dielectric shells. 相似文献
992.
Kim MH Ayral A Park CB Choy JH Oh JM 《Journal of nanoscience and nanotechnology》2011,11(2):1656-1659
We have investigated the diffusion of various solvents on nanoporous membranes with various pore size and surface energy. We have modified the size of pore channel and surface energy of porous membrane through grafting different sized alkyl chain on inorganic membranes. Typically, disc type zirconia membranes with pore size of 3 nm and silica ones with 1 nm pore were purchased from Inocermic Co. Ltd. (Germany), and the surface and pore channel was modified by either octyltriethoxysilane (OTS) with chain length approximately 1 nm or pentyltriethoxysilane (PTS) with chain length approximately 0.5 nm. The water contact angles of both OTS and PTS grafted membrane were larger than 100 degrees indicating the hydrophobically modified surface. Contact angles of hydrophilic and hydrophobic solvents were also examined to obtain exact surface energy (gamma(sv)) of grafted membrane, and the values were determined to be 56.3, 45.3, and 42.2 mN/m for ungrafted, PTS- and OTS-grafted membrane, respectively. The solvent diffusion patterns were evaluated by measuring the concentration gradient of small dye molecule, azobenzene. The diffusion coefficients of various solvents were measured on the basis of Fick's diffusion law. It was concluded that the diffusivity is dependent on the pore size for solvent with low surface tension and on the gamma(sv) value for solvent with high surface tension. 相似文献
993.
Intracellular drug delivery of layered double hydroxide (LDH) nanocarriers have been examined in human osteosarcoma Saos-2 cell culture line by both electron and confocal microscopies. For transmission electron microsopic (TEM) study, LDHs and anticancer drug, methotrexate (MTX) loaded LDHs were synthesized and the particle size was controlled. From the scanning electron microscopic (SEM) studies, morphologies of LDH nanoparticle and its MTX intercalated form were proven to be platelike hexagonal with an average size of approximately 150 nm. In order to understand the cellular penetration behavior, both nanoparticles were treated to human osteosarcoma Saos-2 cell culture lines and the cellular uptake pattern with respect to incubation time was observed by TEM and SEM. We observed that the nanoparticles are attached at the cellular membrane at first and then internalized into the cells via endocytosis within 1 h. Then are located in the intracellular vacuole (endosome). In order to examine the intracellular drug delivery mechanism of LDH nanoparticles, fluorescein 5-isothiocyanate (FITC) labeled MTX was intercalated into LDH and treated on Saos-2 cells. Laser scanning confocal microscopic studies revealed that the FITC-MTX molecules were first internalized with LDH nanocarriers via endocytosis, and located in endosome to deliver loaded drug to target cellular organ. It was, therefore, concluded that LDH could play a role as drug delivery nanocarriers. 相似文献
994.
The self-assembly monolayer (SAM) method was used for membrane fabrication, in which Si wafers were treated separately with N-trimethoxysilylpropyl-n,n,n-tri-n-butylammonium bromide (TMSP-TBA) and N-trimethoxysilylpropyl-n,n,n-trimethylammonium chloride (TMSP-TMA) to form monolayers on the Si surfaces. To grow silicate membranes on the organosilyl-treated Si wafers, a series of silicate sols were prepared with composites of tetraethylorthosilicate (TEOS) and methyltriethoxysilane (MTES) as silicate sources, and tetrapropylammonium bromide (TPABr) was used as an organic template. Their microstructures were investigated in detail by comparing them using SEM and XRD. The use of MTES hindered the formation of microporous channels in the calcined silicate samples. The calcined silicate samples became totally amorphous over 20% loading of MTES. In addition, their structural information was supported by spectroscopic (FT-IR and solid-state 29Si NMR) analyses. 相似文献
995.
Photoresist lithography has been applied to the fabrication of micro/nano devices, such as microfluidic structures, quantum dots, and photonic devices, in MEMS (micro-electro mechanical systems) and NEMS (nano-electro-mechanical systems). In particular, nano devices can be expected to present different physical phenomena due to their three-dimensional (3D) structure. The flexible 3D micro/nano fabrication technique and its process simulation have become among the major topics needed to understand nano-mechanical phenomena. For this purpose, the moving-mask technology and the lithography processes for the positive- and negative-tone photoresists were modeled. The validity of the simulation of the proposed 3D nano/microstructuring was successfully confirmed by comparing the experiment results and the simulated results. Hence, the developed model and the simulation can present and optimize photoresist characteristics and lithography process conditions due to the various 3D nano/microstructures. They could be help in the understanding of nanomaterial and mechanical phenomena. 相似文献
996.
The toxicity of polyaniline (PANI) nanomaterials with four different aspect ratios on human lung fibroblast cells was investigated by cell viability assay, cytotoxicity assay, apoptosis/necrosis measurement, and reactive oxygen species production. The toxicity increased with decreasing aspect ratio of PANI nanomaterials. In contrast, the highest aspect ratio PANI nanomaterials showed similar results with bulk PANI materials. The adverse effect of PANI nanomaterials was also concentration- and time-dependent. Low aspect ratio PANI nanomaterials induced more necrosis and more reactive oxygen species than others. These results provide new understanding of shape-dependent toxicity of nanomaterials. 相似文献
997.
Choi JW Islam AT Lee JH Song JM Oh BK 《Journal of nanoscience and nanotechnology》2011,11(5):4200-4204
In this study an immuno-array for Abeta42 based on scanning tunneling microscopy (STM) was developed using conjugated gold nanoparticle (Au-NP) and antibody (Ab) complex. Fragmented monoclonal Ab against Abeta42 was allowed to immobilize on the Au-dot arrays followed by its target protein Abeta42 and Au NP and Ab complex. The surface structure of Au-NP and Ab complex on Au-dots was investigated with Atomic Force Microscopy and the current profile of fabricated immunosensing element was investigated with STM. The power spectrum derived from the current profile was found to be increasing with higher concentrations of Abeta42 having a detection limit of 100 fg/ml. The proposed technique can be a promising method to construct the highly sensitive and efficient protein chip of immunosensors arrays. 相似文献
998.
Lee EJ Jung CH Hwang IT Choi JH Cho SO Nho YC 《ACS applied materials & interfaces》2011,3(8):2988-2993
A simple and controllable one-step method to fabricate superhydrophobic surfaces on poly(tetrafluoroethylene) (PTFE) films is developed on the base of electron irradiation. When the thickness of PTFE films is higher than the penetration depth of electron beams, electrical charging occurs at the surface of the films because of the imbalance between the accumulation of incident electrons and the emission of secondary electrons. Local inhomogeneity of charge distribution due to this electrical charging results in the nonuniform decomposition of PTFE molecular bonds. As electron fluence increases, surface morphology and surface roughness of the films are dramatically changed. An extremely rough surface with micrometer-sized pores is produced on the surface of PTFE films by electron irradiation at a fluence higher than 2.5 × 10(17) cm(-2).Because of high surface roughness, the irradiated PTFE films exhibit superhydrophobic property with a water contact angle (CA) greater than 150° at fluences ranging from 4 × 10(17) to 1 × 10(18) cm(-2). The surface morphology and corresponding water CA can be controlled by simply changing the electron fluence. This electron irradiation method can be applicable to the fabrication of superhydrophobic surfaces using other low-surface-energy materials including various fluoropolymers. 相似文献
999.
The generation of nucleic acid aptamers with high affinity typically entails a time-consuming, iterative process of binding, separation, and amplification. It would therefore be beneficial to develop an efficient selection strategy that can generate these high-quality aptamers rapidly, economically, and reproducibly. Toward this goal, we have developed a method that efficiently generates DNA aptamers with slow off-rates. This methodology, called VDC-MSELEX, pairs the volume dilution challenge process with microfluidic separation for magnetic bead-assisted aptamer selection. This method offers improved aptamer selection efficiencies through the application of highly stringent selection conditions: it retrieves a small number (<10(6)) of magnetic beads suspended in a large volume (>50 mL) and concentrates them into a microfluidic chamber (8 μL) with minimal loss for continuous washing. We performed three rounds of the VDC-MSELEX using streptavidin (SA) as the target and obtained new DNA aptamer sequences with low nanomolar affinity that specifically bind to the SA proteins. 相似文献
1000.
Effects of acicular ferrite on charpy impact properties in heat affected zones of oxide-containing API X80 linepipe steels 总被引:1,自引:0,他引:1
Hyo Kyung SungSang Yong Shin Wooyeol ChaKyungshik Oh Sunghak Lee Nack J. Kim 《Materials Science and Engineering: A》2011,528(9):3350-3357
This study was concerned with effects of acicular ferrite on Charpy impact properties in heat affected zones (HAZs) of two API X80 linepipe steels containing oxides. In the one steel, Mg and O2 were additionally added to form a larger amount of oxides than the other steel, which was a conventional X80 steel containing a considerable amount of Al and Ti. Various HAZ microstructures were obtained by conducting HAZ simulation tests under different heat inputs of 35 kJ cm−1 and 60 kJ cm−1. Oxides present in the API X80 linepipe steels were complex oxides whose average size was 1-2 μm, and the number of oxides increased with increasing amount of Mg and O2. The volume fraction of acicular ferrite present in the steel HAZs increased with increasing number of oxides, and decreased with increasing heat input. When the volume fraction of acicular in the HAZ was higher than 20%, Charpy impact energy at −20 °C was higher than 100 J as the ductile fracture mode was dominant. Particularly in the steel HAZs having a larger amount of oxides, Charpy impact properties were excellent because oxides worked as nucleation sites of acicular ferrite during welding. Charpy impact properties of the HAZs could be well correlated with the volume fraction of acicular ferrite and number of oxides under different heat input conditions. 相似文献