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871.
The interests in sustained ocular drug delivery have grown rapidly in recent years, with hope to replace repeated intravitreal injections. Microneedles (MNs), which are minimally invasive, have been shown to be a feasible vehicle for sustained drug delivery. However, securing an MN patch in the eye remains challenging. In this study, a new design of hydrogel MNs with interlocking features to achieve self‐adhesion is proposed. Upon swelling, the swollen interlocking features help secure the MNs in place. A new molding process is developed to fabricate MNs with interlocking features that can cause issues when demolding using the regular micromolding process. MNs with two different interlocking feature designs are used in this study and are made with polyvinyl alcohol. MNs with the interlocking features show an 80% increase in adhesion strength and a small amount of increase in penetration force, in comparison to MNs without any feature. The experiments are performed using both a sclera‐mimicking phantom and ex vivo eyes harvested from rabbits and are shown to have comparable results. This study demonstrates the feasibility of incorporating interlocking features to MNs to achieve self‐adhesion that can enable sustained drug delivery via MNs. 相似文献
872.
Validation of surface coating with nanoparticles to improve the flowability of fine cohesive powders
《Particuology》2017
Fluidization of fine cohesive powders is seriously restricted by the strong interparticle cohesion. The rational combination of nanoparticles with fine cohesive powders is expected to obtain composite particles with improved flowability. In this work, we firstly reviewed the sandwich and three-point contact models regarding the fundamental principles of nano-additives in reducing cohesiveness. Based on these previous models, the effects of the size of nanoparticles, their agglomeration and coverage on the surface of cohesive powders in reducing interparticle forces were theoretically analyzed. To validate the theory effectiveness for the irregularly shaped cohesive powders, an extreme case of cubic powders coated with silica nanoparticles was fabricated, and the flowability of the composite particles was determined experimentally. Ultimately, based on force balance of a single particle, a semi-theoretical criterion for predicting the fluidization behavior of coated powders was developed to guide the practical applications of improving the flowability of cohesive powders through structural design and modulation. 相似文献
873.
聚酯薄膜与紫外光(UV)固化光油之间的附着力极差,用胶带拉脱时完全脱落.为此,分别采用AF-201磺化聚酯、YF-40聚丙烯酸树脂、PR-32聚氨酯、EX-40F丙烯酸改性聚氨酯和PX-1010丙烯酸改性聚酯等表面处理剂对聚酯薄膜表面进行涂覆处理,以改善聚酯薄膜的表面性能,提高其与UV光油之间的附着力.附着力测定结果表明,PX-1010丙烯酸改性聚酯可明显提高聚酯薄膜与UV光油的附着力. 相似文献
874.
Jacob Jensen Henrik F. Dam John R. Reynolds Aubrey L. Dyer Frederik C. Krebs 《Journal of Polymer Science.Polymer Physics》2012,50(8):536-545
Electrochromic devices (ECDs) were prepared on flexible substrates using spray coating and slot‐die coating methods. The electrochromic materials were the conjugated electroactive polymers, poly((2,2‐bis(2‐ethylhexyloxymethyl)‐propylene‐1,3‐dioxy)‐3,4‐thiophene‐2,5‐diyl) as a vibrantly colored active material (ECP‐Magenta) and poly(N‐octadecyl‐(propylene‐1,3‐dioxy)‐3,4‐pyrrole‐2,5‐diyl) as a minimally colored, charge balancing material (MCCP). Two electrolyte systems were compared to allow development of fully printable and laminated devices on flexible substrates. Devices of various sizes, up to 7 × 8 cm2, are demonstrated with pixelated devices containing pixel sizes of 4 × 4 mm2 or 13 × 13 mm2. The transmission contrast exhibited by the devices, when switched between the fully bleached and fully colored state, was 58% at a visible wavelength of 550 nm, and the devices exhibited switching times of <10 s. Additionally, we demonstrate the utilization of printed organic photovoltaic devices (with or without the use of a lithium‐polymer battery) to power the devices between the colored and bleached state, illustrating a self‐powered ECD. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012 相似文献
875.
Shotaro Ito Haruhisa Akiyama Miyuki Mori Masaru Yoshida Hideyuki Kihara 《Journal of polymer science. Part A, Polymer chemistry》2020,58(4):568-577
The photoinduced solid–liquid phase transition of azobenzene-based polymers is an attractive method to synthesize stimuli-responsive functional materials. As the structure–property relationships of such materials are not fully understood, a new class of polymer backbone, that is, poly(vinyl ether) (PVE), was studied for the development of azobenzene-based polymers with high thermal stability. For this purpose, a series of azobenzene-based PVEs with different monomer structures were synthesized using a Lewis acid catalyst-based cationic polymerization method. Typical PVEs are viscous polymers with low glass-transition temperatures (Tg's). The flexibility of the polymer backbone improves with the use of alkylene spacers, changing the order of alignment of the mesogenic azobenzene moieties attached to the backbone, leading to high Tg's of the azobenzene-based PVEs. One of the synthesized PVEs shows a high glass-transition temperature of 94 °C, which is 14 °C higher compared to that of the corresponding polymethacrylate. Furthermore, the PVE exhibits photoinduced solid–liquid phase transition from the semicrystalline state. This phase transition material, with its high thermal stability, has the potential for broader applications, such as for the phototuning of adhesion. © 2020 Wiley Periodicals, Inc. J. Polym. Sci. 2020 , 58, 568–577 相似文献
876.
《Physics and Chemistry of Liquids》2012,50(3):169-176
Abstract A dielectric study of H-bond complexes of three acetates namely ethyl acetate, butyl acetate, and benzyl acetate with the proton donor (O-Cresol) has been made. The equilibrium constant and the thermodynamic parameters for the association process as well as the dielectric relaxation process have been determined from the dielectric data using an equation, proposed in our earlier paper. The results obtained being in agreement with the literature values thus support the validity of the proposed equation. 相似文献
877.
878.
Jagoba Iturri Longjian Xue Michael Kappl Luis García‐Fernández W. Jon P. Barnes Hans‐Jürgen Butt Aránzazu del Campo 《Advanced functional materials》2015,25(10):1499-1505
Anatomic differences on the toe pad epithelial cells of torrent and tree frogs (elongated versus regular geometry) are believed to account for superior ability of torrent frogs to attach to surfaces in the presence of running water. Here, the friction properties of artificial hexagonal arrays of polydimethylsiloxane (PDMS) pillars (elongated and regular) in the presence of water are compared. Elongated pillar patterns show significantly higher friction in a direction perpendicular to the long axis. A low bending stiffness of the pillars and a high edge density of the pattern in the sliding direction are the key design criteria for the enhanced friction. The elongated patterns also favor orientation‐dependent friction. These findings have important implications for the development of new reversible adhesives for wet conditions. 相似文献
879.
J. Geerk 《辐射效应与固体损伤》2013,168(1-4):35-36
This overview outlines some basic properties of defects in insulators and describes experimental techniques by which these defects may be characterized. Then the production of defects by various types of particle irradiation is discussed. Finally some discussion is presented of the potential device application of defective crystals, including tunable colour centre lasers, miniaturised optical circuitry and neutron dosimetry. 相似文献
880.