全文获取类型
收费全文 | 1314篇 |
免费 | 226篇 |
国内免费 | 128篇 |
专业分类
化学 | 985篇 |
晶体学 | 14篇 |
力学 | 47篇 |
综合类 | 12篇 |
数学 | 79篇 |
物理学 | 531篇 |
出版年
2024年 | 5篇 |
2023年 | 41篇 |
2022年 | 46篇 |
2021年 | 57篇 |
2020年 | 89篇 |
2019年 | 64篇 |
2018年 | 52篇 |
2017年 | 46篇 |
2016年 | 74篇 |
2015年 | 88篇 |
2014年 | 84篇 |
2013年 | 99篇 |
2012年 | 124篇 |
2011年 | 113篇 |
2010年 | 82篇 |
2009年 | 61篇 |
2008年 | 75篇 |
2007年 | 67篇 |
2006年 | 57篇 |
2005年 | 41篇 |
2004年 | 41篇 |
2003年 | 29篇 |
2002年 | 29篇 |
2001年 | 18篇 |
2000年 | 11篇 |
1999年 | 20篇 |
1998年 | 21篇 |
1997年 | 24篇 |
1996年 | 20篇 |
1995年 | 9篇 |
1994年 | 12篇 |
1993年 | 14篇 |
1992年 | 12篇 |
1991年 | 6篇 |
1990年 | 7篇 |
1989年 | 9篇 |
1988年 | 1篇 |
1987年 | 4篇 |
1984年 | 2篇 |
1982年 | 1篇 |
1980年 | 2篇 |
1978年 | 1篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1969年 | 1篇 |
1966年 | 1篇 |
1955年 | 1篇 |
排序方式: 共有1668条查询结果,搜索用时 0 毫秒
31.
Dou Ma Ping Li Xiangyu Duan Jiazhen Li Pengpeng Shao Dr. Zhongling Lang Lixia Bao Dr. Yuanyuan Zhang Dr. Zhengguo Lin Prof. Dr. Bo Wang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(10):3933-3937
Metal–organic frameworks (MOFs) with long-term stability and reversible high water uptake properties can be ideal candidates for water harvesting and indoor humidity control. Now, a mesoporous and highly stable MOF, BIT-66 is presented that has indoor humidity control capability and a photocatalytic bacteriostatic effect. BIT-66 (V3(O)3(H2O)(BTB)2), possesses prominent moisture tunability in the range of 45–60 % RH and a water uptake and working capacity of 71 and 55 wt %, respectively, showing good recyclability and excellent performance in water adsorption–desorption cycles. Importantly, this MOF demonstrates a unique photocatalytic bacteriostatic behavior under visible light, which can effectively ameliorate the bacteria and/or mold breeding problem in water adsorbing materials. 相似文献
32.
ABSTRACTA short-focus microlens array using dielectric layer and inhomogeneous electric field over a homogeneous nematic liquid crystal (LC) layer is proposed. The top substrate has a planar indium tin oxide (ITO) electrode which is coated on the inner surface. The bottom substrate has strip ITO electrodes which are embedded in the dielectric layers. The inhomogeneous electric field generates a required gradient refractive index profile within the LC layer which, in turn, causes the focusing effect. Due to the thinner LC layer (15 μm), the spherical aberration should be negligible. Moreover, the fabrication process of the proposed microlens array can be easily carried out because of the layer-by-layer configuration. The simulation results show that the focal length of the LC microlens can be continuously tuned from infinity to 0.988 mm with the change of applied voltage. 相似文献
33.
光热治疗是近年来兴起的一种治疗方法,具有靶向性强、适应性广的特点。在光热治疗中,通过光热剂对光的吸收将光能转化为热能,从而实现治疗作用,因而光热剂的光热转化性能直接决定了光热治疗的效果。光热剂的种类丰富,涵盖由无机到有机等组成和性能各异的多种材料。其中,聚吡咯具备良好的生物相容性、优异的光稳定性以及光热转化性能,在光热治疗领域受到广泛关注,是一种拥有巨大应用潜力的光热剂,然而其在光热治疗领域的发展趋势及前景却鲜有报道。本文综述了聚吡咯及其纳米复合材料的制备方法,详述了聚吡咯及其纳米复合材料在光热治疗领域中的应用情况,包括聚吡咯基纳米材料的自身性能和实际光热治疗的效果,指出以聚吡咯为基体或修饰材料来制备具有CT、磁共振、光声显影及光热治疗性能的聚吡咯基复合材料已成为发展趋势。在此基础上,本文还总结了聚吡咯基纳米复合材料在制备和应用中存在的问题,并分析了其在发展过程中遇到的挑战以及在生物医学应用中的前景。 相似文献
34.
The ease of undesirable agglomeration and a low efficiency are two problems that restrict the application of graphite nanoplatelets (GNPs) in epoxy resins (EP). Herein, a new strategy with melamine (MEL) as the precursor to functionalize GNPs chemically, which form a bonding layer that is compatible with epoxy matrix, is reported. The MEL fragments with secondary amine groups were grafted uniformly on the GNPs surface by covalent junctions to exploit the diazonium chemistry. This behavior led to a better dispersion and a stronger interaction with the epoxy matrix and resulted in an enhanced glass transition temperature and bending strength, compared with the pure EP. When only 1 wt% functionalized GNPs (f‐GNPs) was used, the Tg of the modified EP raised of about 15°C compared with pure EP, and the bending strength increased by approximately 39%. The dielectric constant of the EP with f‐GNPs was impacted slightly, and the dielectric loss decreased. At 105 Hz, the dielectric loss of the EP with 1 wt% f‐GNPs decreased by approximately 11% compared with pure EP. Therefore, diazotization modification of the GNPs is a useful approach to improve the compatibility in nanoparticle networks. 相似文献
35.
Dou Ma Ping Li Xiangyu Duan Jiazhen Li Pengpeng Shao Zhongling Lang Lixia Bao Yuanyuan Zhang Zhengguo Lin Bo Wang 《Angewandte Chemie (International ed. in English)》2020,59(10):3905-3909
Metal–organic frameworks (MOFs) with long‐term stability and reversible high water uptake properties can be ideal candidates for water harvesting and indoor humidity control. Now, a mesoporous and highly stable MOF, BIT‐66 is presented that has indoor humidity control capability and a photocatalytic bacteriostatic effect. BIT‐66 (V3(O)3(H2O)(BTB)2), possesses prominent moisture tunability in the range of 45–60 % RH and a water uptake and working capacity of 71 and 55 wt %, respectively, showing good recyclability and excellent performance in water adsorption–desorption cycles. Importantly, this MOF demonstrates a unique photocatalytic bacteriostatic behavior under visible light, which can effectively ameliorate the bacteria and/or mold breeding problem in water adsorbing materials. 相似文献
36.
Zheng-Huan Lin Hong-Yan Dou Jin Li Cheng-Xue Zhao 《Research on Chemical Intermediates》2005,31(9):867-873
The H-abstractions/spin-trapping reactions with primary, secondary and tertiary alcohols of new 'magic blue' reagents, namely,
the blue F113 (CClF2CCl2F) solution containing bis{perfluoro[1-(2-fluorosulfonyl)ethoxy]ethyl} nitroxide (2) and perfluoro[1-nitroso-1-(2-fluorosulfonyl)ethoxy]ethane (3) both generated in the reaction of perfluoro[2-(2-fluorosulfonyl)ethoxy]propionyl peroxide (1) with sodium nitrite in F113 at room temperature, were studied by EPR. Based on the interpretation of the EPR spectra of
the spin adducts, nitroxides, the region-selectivity of H-abstraction has been disclosed and the possible mechanistic paths
of H-abstraction have also been discussed. EPR of H-abstraction by using 'magic blue' reagents can also be used for producing
various hydroxyalkyl radicals from common alcohols. 相似文献
37.
在Na2OSiO2CTABH2O四元水热体系中系统地考察了晶化温度对中孔MCM41分子筛合成及其骨架结构的影响。实验结果表明,提高晶化温度虽然能明显加快晶化速率,缩短晶化时间,但同时样品的结晶度和中孔骨架结构的有序度却被迅速破坏。这些特点与传统沸石的合成过程完全不同,其原因主要是合成MCM4l时所用的模板剂及其在合成中所起的模板作用与传统沸石完全不同。相对低的晶化温度(如100℃)有利于高质量和高热稳定性的中孔MCM4l分子筛的合成。 相似文献
38.
W. W. Zhong You-Ying Di J. M. Dou 《Journal of Thermal Analysis and Calorimetry》2014,115(3):2527-2533
Two novel complexes [Mg(DPC)(H2O)3]·2H2O(s) and Sr2(H2DPC)2(HDPC)2(DPC)(H2O)2(s) were synthesized by the method of liquid phase reflux. X-ray crystallography, chemical analysis, and elemental analysis were applied to characterize the structures and compositions of the two complexes. Low-temperature heat capacities of the complexes were measured over the temperature ranges from 78 to 350 and 78 to 352 K for [Mg(DPC)(H2O)3]·2H2O(s) and Sr2(H2DPC)2(HDPC)2(DPC)(H2O)2(s), respectively. The polynomial regressions as a function of temperature were carried out through least square fitting method according to the experiment points. The polynomial fitted values of the molar heat capacities and the thermodynamic functions relative to the standard reference temperature 298.15 K based on the polynomial equations were derived. In addition, thermal behavior of the two compounds was investigated by thermal analysis techniques, differential scanning calorimetry/thermogravimetric analysis. 相似文献
39.
Shaobin Pan Zhe Zhang Qixiang Feng Jin Zhao Shahid Aziz Liwen Dou Jing Li Luyao Huang Huijiao Yan Xiao Wang Jia Li Daijie Wang 《Journal of separation science》2023,46(10):2300042
Cyperus rotundus L. has been extensively used in ancient medication for the treatment of different disorders worldwide, in which sesquiterpenes are the most representative components. In this study, sesquiterpenes were effectively purified by two-dimensional counter-current chromatography in combination with continuous injection and inner-recycling mode with a solvent system of n-hexane/ethyl acetate/methanol/water (1:0.2:1:0.2, v/v/v/v). For one-dimension separation, continuous injection mode was used with three times injection and the inner-recycling mode was adopted for the separation of two mixtures for two-dimensional separation. Finally, four sesquiterpenoids, including scariodione ( 1 ), cyperenoic acid ( 2 ), scariodione ( 3 ), and α-cyperone ( 4 ), were obtained with purities over 98%. Mass spectrometry and nuclear magnetic resonance were applied to identify their structures. The results from the anti-inflammation effect with zebrafish demonstrated that cyperenoic acid exhibited stronger anti-inflammation activity. Molecular docking results suggested that cyperenoic acid possessed lower binding energies –9.4545 kcal/mol with 1CX2 to form formed hydrogen bond interaction with ARG120. In general, all the obtained findings proved that the strong anti-inflammation capacity of cyperenoic acid can have the potential of being adopted for treating diseases resulting from inflammation. 相似文献
40.
A blue phase liquid crystal (BPLC) lens with multifunction using multi-electrode structure and a dielectric layer with high dielectric constant is proposed. The refractive index of the BPLC can be changed flexibly in different regions. Some functional or technical requirements such as switch between positive and negative lenses can be achieved. The lens reveals a good parabolic refractive index distribution and focus adjustment capacity simultaneously. The applied voltage on the electrodes is regular and computable. To decrease the applied voltage of the proposed lens with a large diameter, a drive-type adopted Fresnel lens is introduced. 相似文献