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81.
Nak‐Yun Sung Eui‐Baek Byun Sun‐Kyu Kwon Young‐Choon Yoo Pil‐Mun Jung Jae‐Hun Kim Jong‐Il Choi Mee‐Ree Kim Ju‐Woon Lee 《应用聚合物科学杂志》2011,120(4):2034-2040
We conducted this study to examine the changes in the molecular structure and physiological activities of silk sericin after γ irradiation. Sericin from Bombyx mori was extracted with an Na2CO3 solution. The molecular weight distribution of sericin increased in the gel permeation chromatography and sodium dodecyl sulfate/polyacrylamide gel electrophoresis results as the irradiation dose increased. Circular dichroism data also revealed that the α‐helix contents decreased with the irradiation dose. Ultraviolet absorption was shown a different pattern between the irradiated and unirradiated sericin. However, the Fourier transform infrared spectrum was not changed in all of the groups. Furthermore, the irradiated sericin was significantly increased in 2,2‐diphenyl‐1‐picryl‐hydrazil radical scavenging, and the tyrosinase inhibitory activities increased with irradiation dose. Therefore, γ irradiation was an effective method for producing high‐molecular‐weight sericin and for developing functional foods and cosmetics. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 相似文献
82.
Carbon-coated Li1.1V0.9O2 powder was prepared by dissolving pure crystalline Li1.1V0.9O2 powder in an ethanol solution containing 10 wt% sucrose and sintering it under an argon atmosphere. The structures of the bare and carbon-coated Li1.1V0.9O2 powders were analyzed using X-ray diffraction, Raman spectroscopy, scanning electron microscopy, and transmission electron microscopy. These powders were used as anode active materials for lithium ion batteries in order to determine the electrochemical properties via cyclic voltammetry (CV) and constant current methods. CV revealed the carbon-coated Li1.1V0.9O2 anode to have better reversibility during cycling than the bare Li1.1V0.9O2 anode. Carbon-coated Li1.1V0.9O2 also showed a higher specific discharge and charge capacities, as well as lower electrolyte and interfacial resistance properties. The observed specific discharge and charge capacities of the carbon-coated Li1.1V0.9O2 anode were 330 mAh/g and 250 mAh/g, respectively, in the first cycle. In addition, the cyclic efficiency of this cell was 75.8% in the first cycle. After 20 cycles, the specific capacity of the Li1.1V0.9O2 anode was reduced to approximately 50% of its initial capacity, irrespective of the presence of a carbon coating. 相似文献
83.
Eui-Hyun Ryu Jun Ho Lee Young Sun Lee Ja-Min Gu Seong Huh Suk Joong Lee 《Inorganic chemistry communications》2011,14(10):1648-1651
Size-controlled crystalline nanocubic coordination polymer particles from chiral Zn-salen and Co(II) have been obtained. PXRD patterns show that these particles have an identical unit cell regardless of a wide range of size distributions. Furthermore, cubic particles with epitaxial layers have been obtained with a simple manipulation during the synthesis. 相似文献
84.
A Review of Three‐Dimensional Resistive Switching Cross‐Bar Array Memories from the Integration and Materials Property Points of View 下载免费PDF全文
Jun Yeong Seok Seul Ji Song Jung Ho Yoon Kyung Jean Yoon Tae Hyung Park Dae Eun Kwon Hyungkwang Lim Gun Hwan Kim Doo Seok Jeong Cheol Seong Hwang 《Advanced functional materials》2014,24(34):5316-5339
Issues in the circuitry, integration, and material properties of the two‐dimensional (2D) and three‐dimensional (3D) crossbar array (CBA)‐type resistance switching memories are described. Two important quantitative guidelines for the memory integration are provided with respect to the required numbers of signal wires and sneak current paths. The advantage of 3D CBAs over 2D CBAs (i.e., the decrease in effect memory cell size) can be exploited only under certain limited conditions due to the increased area and layout complexity of the periphery circuits. The sneak current problem can be mitigated by the adoption of different voltage application schemes and various selection devices. These have critical correlations, however, and depend on the involved types of resistance switching memory. The problem is quantitatively dealt with using the generalized equation for the overall resistance of the parasitic current paths. Atomic layer deposition is discussed in detail as the most feasible fabrication process of 3D CBAs because it can provide the device with the necessary conformality and atomic‐level accuracy in thickness control. Other subsidiary issues related to the line resistance, maximum available current, and fabrication technologies are also reviewed. Finally, a summary and outlook on various other applications of 3D CBAs are provided. 相似文献
85.
Highly Fluorescent and Color‐Tunable Exciplex Emission from Poly(N‐vinylcarbazole) Film Containing Nanostructured Supramolecular Acceptors 下载免费PDF全文
Jong H. Kim Byeong‐Kwan An Seong‐Jun Yoon Sang Kyu Park Ji Eon Kwon Chang‐Keun Lim Soo Young Park 《Advanced functional materials》2014,24(19):2746-2753
Highly fluorescent excited‐state charge‐transfer complexes (exciplexes) formed at the interfacial region between a polymeric donor matrix, here, poly(N‐vinylcarbazole), and embedded nanostructured acceptors are characterized for their photophysical properties. Exciplex‐to‐exciton emission switching is observed after solvent vapor annealing (SVA) due to the size evolution of the nanostructures beyond the exciton diffusion length. Color‐tunable exiplex emission (sky blue, green, and orange) is demonstrated for three different nanostructured acceptors with the same HOMO–LUMO gap (i.e., the same blue excitonic emission) but with different electron affinity. White‐emitting poly(N‐vinylcarbazole) film is also fabricated, simply by incorporating mixed supramolecular acceptors, which provide independent exciplex emissions. This study presents important insights into the excited‐state intermolecular interaction at the well‐defined nanoscale interface and suggests an efficient way to obtain multicolored exciplex emissions. 相似文献
86.
Characterization of Fluxing and Hybrid Underfills with Micro‐encapsulated Catalyst for Long Pot Life
Yong‐Sung Eom Ji‐Hye Son Keon‐Soo Jang Hak‐Sun Lee Hyun‐Cheol Bae Kwang‐Seong Choi Heung‐Soap Choi 《ETRI Journal》2014,36(3):343-351
For the fine‐pitch application of flip‐chip bonding with semiconductor packaging, fluxing and hybrid underfills were developed. A micro‐encapsulated catalyst was adopted to control the chemical reaction at room and processing temperatures. From the experiments with a differential scanning calorimetry and viscometer, the chemical reaction and viscosity changes were quantitatively characterized, and the optimum type and amount of micro‐encapsulated catalyst were determined to obtain the best pot life from a commercial viewpoint. It is expected that fluxing and hybrid underfills will be applied to fine‐pitch flip‐chip bonding processes and be highly reliable. 相似文献
87.
This paper presents a 0.13 μm CMOS 3‐level envelope delta‐sigma modulation (EDSM) RF signal generator, which synthesizes a 2.6 GHz‐centered fully symmetrical 3‐level EDSM signal for high‐efficiency power amplifier architectures. It consists of an I‐Q phase modulator, a Class B wideband buffer, an up‐conversion mixer, a D2S, and a Class AB wideband drive amplifier. To preserve fast phase transition in the 3‐state envelope level, the wideband buffer has an RLC load and the driver amplifier uses a second‐order BPF as its load to provide enough bandwidth. To achieve an accurate 3‐state envelope level in the up‐mixer output, the LO bias level is optimized. The I‐Q phase modulator adopts a modified quadrature passive mixer topology and mitigates the I‐Q crosstalk problem using a 50% duty cycle in LO clocks. The fabricated chip provides an average output power of –1.5 dBm and an error vector magnitude (EVM) of 3.89% for 3GPP LTE 64 QAM input signals with a channel bandwidth of 10/20 MHz, as well as consuming 60 mW for both channels from a 1.2 V/2.5 V supply voltage. 相似文献
88.
Boeun Cho Seong Hun Yu Moo Hyung Lee Juhee Lee Jun Young Lee Jeong Ho Cho Moon Sung Kang 《Organic Electronics》2014,15(12):3439-3444
We demonstrate the versatility of the threshold voltage control for organic thin-film transistors (OTFTs) based on formation of discontinuous pn-heterojunction on the active channel layer. By depositing n-type dioctyl perylene tetracarboxylic diimide molecules discontinuously onto base p-type pentacene thin films (the formation of the discontinuous pn-heterojunction), a positive shift of the threshold voltage was attained which enabled realizing a depletion-mode transistor from an original enhancement-mode pristine pentacene transistor. Careful control of the threshold voltage based on this method led assembling a depletion-load inverter comprising a depletion-mode transistor and an enhancement-mode transistor connected in series that yielded tunable signal inversion voltage approaching 0 V. In addition, the tunability could be applied to improve the program/erase signal ratio for non-volatile transistor memories by more than 4 orders of magnitude compared to reference memory devices made of pristine pentacene transistors. 相似文献
89.
Kyung Hwan Oh Seong Min Kim Mi Jung Lee Jin Kyoon Park 《Advanced Synthesis \u0026amp; Catalysis》2015,357(18):3927-3935
A direct method for the arylation of 1,2‐azolo[1,5‐a]pyridines has been developed. In the process, the fused pyridines react with aryl halides in the presence of the palladium complex Pd(OAc)2(Phen) as a catalyst and copper(I) chloride (CuCl) as a Lewis acid to form arylated derivatives. While pyrazolo[1,5‐a]pyridines and [1,2,4]triazolo[1,5‐a]pyridines are arylated at ortho‐positions of their pyridine rings using this method, in situ ring‐opening of the formed C‐7 arylated [1,5‐a]pyridine takes place to generate the 2,6‐disubstituted pyridine. Also, upon treatment with lithium diisopropylamide (LDA), C‐7 arylated pyrazolo[1,5‐a]pyridine‐3‐carboxylates react to produce diversely substituted 2,6‐disubstituted pyridines. Finally, a sequential C‐3 arylation was accomplished through a two‐step sequence involving hydrolysis of pyrazolo[1,5‐a]pyridine‐3‐carboxylates followed by the bimetallic Pd/Cu‐catalyzed decarboxylative coupling reaction with aryl bromide.
90.