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31.
Mn4+-activated double perovskite phosphors with composition diversity have presented excellent luminescent performances. However, the charge imbalance between Mn4+ and matrix cations would increase non-radiative recombination and reduce the structural stability. Here, novel high-efficiency stable Li+/Mn4+ co-incorporated Sr2YSbO6 red phosphors are successfully synthesized via a solid-state reaction method for warm w-LEDs, where the Li+ ions have the effect of charge balance for Sr2YSbO6:Mn4+ and reduce the non-radiative energy transfer among Mn4+ ions. It is demonstrated that the substitution of Li+–Mn4+ pairs for Sb5+ can enhance the bonding with low-shifted diffraction peaks and high emission intensity, and prolong the decay lifetime, compared with those of Mn4+ single-doped ones. Impressively, the thermal stability is enhanced to 89.72% from 84.61% at the original value of 303 K. Finally, a w-LED device based on the optimal phosphor Sr2YSbO6:0.01Mn4+/0.01Li+ red component exhibits a correlated color temperature of 4487 K and color rendering index of 80.2. Therefore, the incorporated Li+ ions serve as both charge compensator and co-activator in Mn4+-activated double perovskite phosphors with the aim of high luminescent performance and thermal stability. 相似文献
32.
Christian Balischewski Hyung-Seok Choi Karsten Behrens Alkit Beqiraj Thomas Körzdörfer André Geßner Dr. Armin Wedel Prof. Dr. Andreas Taubert 《ChemistryOpen》2021,10(2):272-295
Metal sulfides are among the most promising materials for a wide variety of technologically relevant applications ranging from energy to environment and beyond. Incidentally, ionic liquids (ILs) have been among the top research subjects for the same applications and also for inorganic materials synthesis. As a result, the exploitation of the peculiar properties of ILs for metal sulfide synthesis could provide attractive new avenues for the generation of new, highly specific metal sulfides for numerous applications. This article therefore describes current developments in metal sulfide nanoparticle synthesis as exemplified by a number of highlight examples. Moreover, the article demonstrates how ILs have been used in metal sulfide synthesis and discusses the benefits of using ILs over more traditional approaches. Finally, the article demonstrates some technological challenges and how ILs could be used to further advance the production and specific property engineering of metal sulfide nanomaterials, again based on a number of selected examples. 相似文献
33.
Hua Lei Meixuan Wu Ying Liu Fan Mo Jiayao Chen Shilong Ji Yan Zou Xiaoping Dong 《中国化学快报》2021,32(7):2317-2321
Photocatalysis technology has been proved to be a potential strategy for removal of organic dyes, however high-power light sources are generally necessary to initiate photocatalytic reaction. In this work, we employed an excellent photocatalyst of Bi2WO6 with visible light harvest and meanwhile an intrinsic ferroelectricity, which realized the efficient degradation of organic dye via the synergetic photopiezocatalysis. Through coupling the illumination by a low-power (9 W) LED and the ultrasonic vibration (120 W) by an ultrasonic cleaner, the nanoflower-like Bi2WO6 composed of ultrathin nanosheets showed a much more enhanced photopiezocatalysis performance for purification of organic dye than the individual photocatalysis and piezocatalysis. Furthermore, the high mineralization efficiency and the good durability of the Bi2WO6 catalyst were demonstrated. The possible mechanism of photopiezocatalysis was finally proposed, where the ultrasound-induced piezoelectric field in Bi2WO6 drove photo-generated electrons and holes to diffuse along opposite directions, consequently promoting the separation efficiency of charge carriers. This work indicates that the synergetic photopiezocatalysis by coupling irradiation and ultrasonic vibration is a promising strategy to purify organic pollutants in wastewater. 相似文献
34.
Two kinds of 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) dyads BDP-OH containing 4-hydroxystyrene groups and BDP-PY bearing pyridinyl units were prepared. In addition, a naphthalene derivative NAP-PY modified by pyridinyl moieties substituent was made. The above three dyads could be used to construct white-light emission (WLE) material by a supramolecular engineering strategy due to their three primary colors of blue, green and red. The supramolecular correlations between the hydroxyl group of BDP-OH and the pyridinyl groups of NAP-PY and BDP-PY were confirmed by 1H NMR titration, 2D NOESY and FTIR. A fluorescence monitor application was carried out based on the realization of WLE. This work might be useful for designing other WLE supramolecular systems and image display. 相似文献
35.
以邻苯二胺、 2,5-二氨基苯磺酸和三氯化铝为原料, 通过无溶剂法大量制备了高效的红色荧光碳点 (R-CDs). 制得的碳点尺寸大约为2.4 nm, 含有13%的氮元素, 主要由高度石墨化的碳核及覆盖在其表面的大量官能团构成. 在不同的波长光激发下, 碳点在乙醇溶液中表现出不依赖于激发的红光发射, 其荧光峰位于 704 nm, 最大量子产率达到22%. 由于R-CDs具有优异的光学性质, 利用其构筑了紫外光激发的碳基白色发光二极管, 其色坐标为(0.33, 0.33), 非常接近自然光. 该研究为高效红色荧光碳点的大量制备提供了一种新路径, 同时拓宽了其在白光器件中的应用. 相似文献
36.
采用高温固相法成功制备了Na3Sc2-x-y(PO4)3∶xTm3+,yDy3+荧光粉,利用X射线衍射仪、扫描电子显微镜和荧光光谱仪对荧光粉进行了物相、形貌和发光性能进行了表征。 在Na3Sc2(PO4)3∶0.06Tm3+,yDy3+荧光粉中,物质的量分数6%的Tm3+和6%的Dy3+在360 nm激发下呈现出白光发射,其发射光谱在460~685 nm范围内存在Tm3+位于457 nm的特征发射峰,对应于Tm3+的3H6→1D2跃迁,以及Dy3+位于483、577和672 nm处的3个特征发射峰,分别对应于Dy3+的4F9/2→6H15/2、4F9/2→6H13/2和4F9/2→6H11/2的跃迁。 观测到Na3Sc2(PO4)3∶Tm3+荧光粉的发射光谱与Na3Sc2(PO4)3∶Dy3+的激发光谱有较好的重叠,且Tm3+的荧光寿命随Dy3+浓度的增加逐渐降低,因此在Na3Sc2(PO4)3∶Tm3+,Dy3+荧光粉中存在Tm3+向Dy3+的能量传递。 利用Dexter和Reisfeld近似分析了能量转移机制,发现从Tm3+到Dy3+的能量传递临界距离为1.6 nm,能量传递过程是通过偶极-偶极相互作用进行的。 Na3Sc2(PO4)3∶0.06Tm3+,0.06Dy3+荧光粉具有较好的耐受热猝灭性能,在423、473和523 K时的发射强度分别为298 K时发射强度的97.6%、89.2%和78.6%。 随着Dy3+浓度的增加,Na3Sc2(PO4)3∶0.06Tm3+,yDy3+荧光粉的发光颜色由蓝色转变为白色,再由白色变黄色。 Na3Sc2(PO4)3∶Tm3+,Dy3+荧光粉作为一种可调色或单相白光荧光粉在发光二极管上具有潜在的应用前景。 相似文献
37.
Jing Sun Junsen Jia Bo Zhao Jingjing Yang Manjeet Singh Zhongfu An Hua Wang Bingshe Xu Wei Huang 《中国化学快报》2021,32(4):1367-1371
A purely organic D-π-A-π-D type emitter showing thermally activated delayed fluorescence(TADF) and room temperature phosphorescence(RTP) was designed and synthesized by utilizing the benzophenone as an acceptor and the N-phenyl-2-napthylamine as a donor moiety.It exhibits considerable TADF character in doped PMMA film and room temperature phosphorescence with a long lifetime of 74 ms at466 nm in solid state.The devices with the configuration of ITO/Mo_2 O_3(4 nm)/mCP(30 nm)/mCP:x wt%NP2 BP/TmTyPB(60 nm)/LiF(1.5 nm)/AI(100 nm) were prepared by vacuum evaporation to explore their electroluminescent performance.Intere stingly,the non-doped device has obtained near-white emission with a fluorescence emission peak at 475 nm and a phosphore scence emission peak at 563 nm having the CIE coordinate of(0.23,0.32) and the maximum external quantum efficiency of 1.09%. 相似文献
38.
39.
Tatiana Chernogorova Radoslav Valkov 《Numerical Methods for Partial Differential Equations》2015,31(3):822-846
We consider the locally one‐dimensional backward Euler splitting method to solve numerically the Hull and White problem for pricing European options with stochastic volatility in the presence of a mixed derivative term. We prove the first‐order convergence of the time‐splitting. The parabolic equation degenerates on the boundary x = 0 and we apply a fitted finite volume scheme to the equation to resolve the degeneracy and derive the fully discrete problem as we also investigate the discrete maximum principle. Numerical experiments illustrate the efficiency of our difference scheme. © 2014 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 31: 822–846, 2015 相似文献
40.
《Current Applied Physics》2015,15(3):248-252
Red phosphors Ca9Bi1-x(PO4)7:xEu3+ (x = 0.06, 0.10, 0.20, 0.30, 0.40, 0.50, 0.60, 0.70, 0.80 and 1.00) were synthesized by a conventional solid-state reaction (SSR) route. The X-ray diffraction patterns, photoluminescence spectra, ultraviolet–visible reflection spectroscopy, decay time and the International Commission on Illumination (CIE) chromaticity coordinates of these compounds were characterized and analyzed. The Eu-doped Ca9Bi(PO4)7 phosphors exhibited strong red luminescence which peaks located at 615 nm due to the 5D0→7F2 electric dipole transition of Eu3+ ions after excitation at 393 nm. Ultraviolet–visible spectra indicated that the band-gap of Ca9Bi0.30(PO4)7:0.70Eu3+ is larger than that of Ca9Bi(PO4)7. The results indicate that the phosphor Ca9Bi0.30(PO4)7:0.70Eu3+ can be a suitable red-emitting phosphor candidate for LEDs. 相似文献