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561.
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The structure of A-Si:H films can be changed by substitutional doping of boron and phosphours dopants. Proper regulation of technological parameters, Ts and r. f. power, can result in a mode transformation from amorphous morphology into microcrystalline or polysilicon like one. The crystallization of amorphous silicon film leads to a further reduction in its room-temperature resistivity by about three order of magnitude and a reduction in its activation energy of electrical conductivity. 相似文献
563.
本文研究了空间最佳N冲击过渡问题(时间任意),导出了发动机点火过程中伴随系统的积分,从而得到了产生空间极值曲线场的程序。 相似文献
564.
A heterostructure of n-type hydrogenated nanocrystalline silicon (nc-Si:H) film with p-type crystalline silicon, i.e., (n)nc-Si:H/(p)C-Si, was fabricated to investigate carrier characteristics and transport. After electrical experiments, carrier information, such as hole and electron as well as 2-dimension electronic gas in the studied system, was identified respectively. The forward current conduction was analyzed while the reverse current transport was distinguished as different mechanisms within the different range of negative applied voltage. The performed study also leads us to ascribe the main origin of short transient times on the produced structure to a tunneling mechanism. 相似文献
565.
Ouyang C Liu H Qian X Lin H Chen N Li Y 《Dalton transactions (Cambridge, England : 2003)》2011,40(14):3553-3557
The organic charge-transfer (CT) complex nanostructures of CuTCPQ (copper tetracyanopentacenequinodimethane) were first successfully fabricated by organic solid phase reaction. The morphologies of CuTCPQ nanosrods can be prepared by controlling the reaction temperature. The electron field-emission properties on these nanostructures were investigated. The current density and turn-on field are 3.5 mA cm(-2) and 2.70 V μm(-1) for the nanorods of CuTCPQ. The results demonstrate that the nanorods of CuTCPQ are potential candidates for field emission cathodes. Stable and reproducible current-controlled electrical switch has been observed in amorphous organic nanorods of CuTCPQ films. The current-voltage characteristics reveal an abrupt decrease in impedance form 1.2 MΩ to less than 1.1kΩ. The maximum ON/OFF ratio of CuTCPQ nanorod arrays is up to 1100. 相似文献
566.
567.
Gao X Wang Y Liu X Chan TL Irle S Zhao Y Zhang SB 《Physical chemistry chemical physics : PCCP》2011,13(43):19449-19453
Ripples naturally occur in graphene sheets. First-principles calculations reveal that, by altering the pyramidalization angles of the carbon atoms, these ripples can be used to direct the chemical reactivity of graphene towards hydrogenation. A fraction of the carbon atoms of a rippled graphene, located around the crests and troughs, show significantly increased reactivity. The remaining carbon atoms have comparable reactivity to those in a flat graphene. To illustrate the increased reactivity, we show that hydrogenation becomes exothermic when the characteristic ratio between the amplitude and wavelength reaches ~0.55. This finding offers a practical chemical venue for regioselectivity control of graphene functionalization. While the rippling does not directly affect the band gap of the graphene, the rippling-induced hydrogenation does. 相似文献
568.
One- and zero-dimensional organic/inorganic heterostructure materials have been attracting considerable attention in materials science because of their outstanding optical and electrical properties and high tailorability in terms of composition, structure, and morphology. Strong interactions between the organic and inorganic units can lead to novel or improved physical or chemical performance relative to that of the individual components, thereby realizing synergistic ("1 + 1 > 2") performance. In this tutorial review, we discuss the synthetic methods available for preparing heterostructures incorporating diverse components; the functionality of the heterostructure materials; and their potential applications in the fields of electronics, optics, biology, and catalysis. The future development of such heterostructure materials will require deeper understanding of organic-inorganic or organic-organic interfaces on the nanoscale, collective phenomena, and interparticle coupling. 相似文献
569.
Zheng H Li Y Zhou C Li Y Yang W Zhou W Zuo Z Liu H 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(7):2160-2167
The mild and highly efficient thiol-ene click reaction has been used to construct a rotaxane incorporating dibenzo-24-crown-8 (DB24C8) and a dibenzylammonium-derived thread in high yield under the irradiation of UV light. A rotaxane containing a disulfide linkage in the macrocycle was also synthesized by the thiol-ene click reaction. It has been demonstrated that the formation of the [2]rotaxane with the disulfide bond in the macrocycle occurs by a mechanism that is different to the threading-followed-by-stoppering process. The successful construction of a rotaxane directly from its constituent components, the macrocycle containing a disulfide linkage and the dibenzylammonium hexafluorophosphate salt, suggests that the space within the macrocycle incorporating the disulfide linkage is smaller than the phenyl unit and a plausible reaction mechanism has been proposed as follows: A small amount of the initiator forms two radicals upon the absorption of UV irradiation; the radicals act as a "key" to "unlock" the disulfide bond in the macrocycle. The resulting crown ether like moiety in the macrocycle is clipped around the ammonium ion center in the dumb-bell-shaped compound. The [2]rotaxane is generated upon recombination of the disulfide linkage. 相似文献
570.