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981.
铜氧化物高温超导体的发现, 打破了基于电声子相互作用BCS理论所预言的超导转变温度极限, 掀开了高温超导材料探索和高温超导机理研究的序幕. 根据掺杂类型的不同, 铜氧化物超导材料可以分为空穴型掺杂和电子型掺杂两类. 受限于样品, 对电子型掺杂铜氧化物的研究工作远少于空穴型掺杂体系. 本文简要回顾有关电子型掺杂铜氧化物超导体近期研究成果, 通过对比电子型掺杂和空穴型掺杂铜氧化物的相图来阐明电子型掺杂铜氧化物的研究对探索高温超导机理的必要性, 并特别针对电子型掺杂样品制备中的关键因素“退火过程”展开讨论. 结合课题组最新实验结果和相关实验报道我们发现电子型掺杂铜氧化物超导体在制备过程中除受到温度和氧分压的影响外, 退火效果还受到界面应力的强烈调制. 在综合考虑样品生长过程中温度、气氛及应力等多种因素的基础上, 探讨了“保护退火”方法导致电子型体系化学掺杂相图变化的起因. 相似文献
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985.
Chun Lian Zhang Xi Fu Jiang Li Yang Shu Hua Zhang Shao Ming Shi 《Journal of Cluster Science》2014,25(2):459-466
A rare heterometallic cluster-based polymer [Cu4(Hbhea)4(μ 2-OCH3) K(CH3OH))] n ·(H2O) n (1) (H3bhea = 2-[bis-(2-hydroxy-ethyl)-amino]-ethanesulfonic acid), has been synthesized and structurally determined by single crystal X-ray diffraction, elemental analysis. Crystallographic unit of 1 consists of four Cu(II), four Hbhea ligands, one methanol molecule, one methanol anion, one K ion and one crystal lattice water and formed anion cluster [Cu4(Hbhea)4(CH3O)]? which further constructed a 3-D polymer by linking the six-coordination K ions. 相似文献
986.
Qiu Ping Huang Shu Hua Zhang Hai Yang Zhang Gui Li Mei Chun Wu 《Journal of Cluster Science》2014,25(5):1489-1499
A nano-double-bowl-like heptanuclear nickel cluster [Ni7(mmp)6(OH)6]2·(ClO4)2·12H2O (1, Hmmp is 2-methoxy-6-methyliminomethyl-phenol) has been synthesized through the microwave-assisted reaction of Ni(ClO4)2·6H2O with 2-hydroxy-3-methoxy-benzaldehyde (Hhmb) and methylamine in distilled water only 29 min. The core of the complex 1 can be described as a double-bowl-like, while the dodecanuclear water cluster stands on the bowl. The magnetic investigation shows that 1 displays very weak ferromagnetic coupling between NiII ions. 相似文献
987.
Weizhao Hu Bibo Wang Xin Wang Hua Ge Lei Song Jian Wang Yuan Hu 《Journal of Thermal Analysis and Calorimetry》2014,117(1):27-38
Ethyl cellulose, a widely used bio-degradable shell material, microencapsulated ammonium polyphosphate (MAPP) was added to the bio-degradable poly(butylene succinate) (PBS) to improve its flame retardancy, compatibility, and thermal stability. The MAPP was well characterized by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy (SEM), water contact angle, and thermogravimetric (TG) analysis. The SEM results indicate the improved dispersion of MAPP into PBS matrix and the formation of the strong interfacial adhesion between MAPP and PBS than APP. With the incorporation of MAPP and char-forming agent into PBS, the limiting oxygen index of the composite was increased to 35.5 %, and the sample can pass the UL-94 V-0 rating, while the un-microencapsulated counterpart cannot reach the rating. The cone calorimeter test showed that the peak heat release rate was decreased by 46.7 % and the burning time was also prolonged compared to the pure PBS. The increased melt flow index and rheology test indicated the increase of viscosity and the improvement of anti-dripping properties. Moreover, the mechanical properties and thermal stability of MAPP composite were also obviously enhanced after the microencapsulation by mechanical, dynamical mechanical thermal analysis, and TG analysis. 相似文献
988.
利用高温固相法,合成出Eu2+、Ce3+、Mn2+共掺的Ca8Mg(SiO4)4Cl2系列绿色荧光粉。通过XRD表征了这些荧光粉的结构,通过分子荧光光谱仪研究了它们的室温发光性能。首先调查了Eu2+掺杂的Ca8Mg(SiO4)4Cl2绿色荧光粉发光性能,随后引入Ce3+、Mn2+提高了Ca8Mg(SiO4)4Cl2∶Eu2+在紫外光区的吸收强度及绿光发射强度。最后将筛选出来的荧光粉与InGaN-LED芯片组装制作成单一绿光LED器件,利用Ca7.8215MgSi4O16Cl2∶0.0525Eu2+,0.056Ce3+,0.070Mn2+所制作成的绿光LED器件发光最强,在20mA电流激发下,此LED发很强的绿光,其电致发光光谱所对应的色坐标值为:x=0.26,y=0.55。 相似文献
989.
Metal Oxide‐Coated Three‐Dimensional Graphene Prepared by the Use of Metal–Organic Frameworks as Precursors
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Xianhong Rui Wenhui Shi Prof. Qingyu Yan Prof. Hua Zhang 《Angewandte Chemie (International ed. in English)》2014,53(5):1404-1409
A simple method for the preparation of metal‐oxide‐coated three‐dimensional (3D) graphene composites was developed. The metal–organic frameworks (MOFs) that served as the precursors of the metal oxides were first synthesized on the 3D graphene networks (3DGNs). The desired metal oxide/3DGN composites were then obtained by a two‐step annealing process. As a proof‐of‐concept application, the obtained ZnO/3DGN and Fe2O3/3DGN materials were used in a photocatalytic reaction and a lithium‐ion battery, respectively. We believe this method could be extended to the synthesis of other metal oxide/3DGN composites with 3D structures simply through the appropriate choice of specific MOFs as precursors. 相似文献
990.
The hydration of NaCl has been widely studied and believed to be important for understanding the mechanisms of salt dissolution in water and the formation of ice nucleus, cloud, and atmospheric aerosols. However, understanding on the poly-NaCl ion pair interacting with water is very limited. Here, we investigated the adsorption of water molecules on (NaCl)3, using both theoretical calculations and anion photoelectron spectroscopy measurements. The calculated vertical detachment energies and the experimental ones agree well with each other. Furthermore, we found that, for neutral (NaCl)3(H2O) n (n = 2–7) clusters, the water-doped cuboid and structures formed by adding water molecules on the Na–Cl edges of the cuboid are energetically favored; water molecules preferentially bind to the Na–Cl edge if the NaCl ion pair has larger partial charges than others. We also found the anionic structures are more various compared with neutral ones, and the Na+ and Cl? ions are hydrated more easily in the anionic clusters than in the corresponding neutrals. 相似文献