全文获取类型
收费全文 | 7632篇 |
免费 | 1390篇 |
国内免费 | 1115篇 |
专业分类
化学 | 5948篇 |
晶体学 | 169篇 |
力学 | 366篇 |
综合类 | 49篇 |
数学 | 964篇 |
物理学 | 2641篇 |
出版年
2024年 | 27篇 |
2023年 | 166篇 |
2022年 | 186篇 |
2021年 | 289篇 |
2020年 | 367篇 |
2019年 | 387篇 |
2018年 | 313篇 |
2017年 | 287篇 |
2016年 | 432篇 |
2015年 | 444篇 |
2014年 | 509篇 |
2013年 | 660篇 |
2012年 | 715篇 |
2011年 | 752篇 |
2010年 | 498篇 |
2009年 | 477篇 |
2008年 | 502篇 |
2007年 | 418篇 |
2006年 | 393篇 |
2005年 | 304篇 |
2004年 | 302篇 |
2003年 | 213篇 |
2002年 | 268篇 |
2001年 | 199篇 |
2000年 | 145篇 |
1999年 | 133篇 |
1998年 | 78篇 |
1997年 | 86篇 |
1996年 | 56篇 |
1995年 | 43篇 |
1994年 | 59篇 |
1993年 | 38篇 |
1992年 | 32篇 |
1991年 | 41篇 |
1990年 | 37篇 |
1989年 | 31篇 |
1988年 | 32篇 |
1987年 | 22篇 |
1986年 | 18篇 |
1985年 | 26篇 |
1984年 | 13篇 |
1983年 | 14篇 |
1982年 | 12篇 |
1981年 | 7篇 |
1979年 | 8篇 |
1978年 | 8篇 |
1977年 | 7篇 |
1976年 | 7篇 |
1975年 | 9篇 |
1971年 | 6篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
941.
Wei Y Yang R Zhang YX Wang L Liu JH Huang XJ 《Chemical communications (Cambridge, England)》2011,47(39):11062-11064
γ-AlOOH(boehmite)@SiO(2)/Fe(3)O(4) porous magnetic microspheres with high adsorption capacity toward heavy metal ions were found to be useful for the simultaneous and selective electrochemical detection of five metal ions, such as ultratrace zinc(II), cadmium(II), lead(II), copper(II), and mercury(II), in drinking water. 相似文献
942.
Zheng X Zhang L Li J Luo S Cheng JP 《Chemical communications (Cambridge, England)》2011,47(45):12325-12327
Magnetic polyoxometalates (POMs) are obtained by a simple sonication between functionalized magnetic nanoparticles and polyoxometalates. This material can be used not only as a highly active acid catalyst, but also as a catalyst support for chiral amines. 相似文献
943.
Li D Yang Z Zhao G Long Y Lv B Li C Hiew S Ng MT Guo J Tan H Zhang H Li T 《Chemical communications (Cambridge, England)》2011,47(26):7479-7481
It is demonstrated that the shapes and magnitudes of DNA writhe can be precisely manipulated solely through maneuvering the nucleotide sequence of DNA and without the assistance of topoisomerases. 相似文献
944.
Li Y Shi L Qin LX Qu LL Jing C Lan M James TD Long YT 《Chemical communications (Cambridge, England)》2011,47(15):4361-4363
A green fluorescent protein chromophore inspired chemosenor for Zn(2+) was designed and synthesized. A Zn(2+) specific fluorescence enhancement was observed due to restricted rotation between the 1,10-phenanthroline and imidazolone moieties. 相似文献
945.
Wang MX Long LS Huang RB Zheng LS 《Chemical communications (Cambridge, England)》2011,47(35):9834-9836
Four lanthanide-based metal-organic frameworks, [Emim][Ln(1.5)(2,5-tdc)(2)]Cl(1.5-x)Br(x) (Ln = Nd 1, Eu 2) and [Emim][Ln(2,5-tdc)(2)] (Ln = Nd 3, Eu 4) (2,5-tdc = thiophene-2,5-dicarboxylate, Emim = 1-methyl-3-ethylimidazolium), were synthesized under ionothermal conditions. Compounds 1 and 2 crystallize in the polar space group P2(1)2(1)2, while 3 and 4 crystallize in the central symmetry space group P2(1)/c. Luminescence studies revealed a significantly higher quantum yield of 4 than that of 2, with similar lifetimes. It is clear that the coordination of the halide ions has profound effects on the structures and properties of these lanthanide-based metal-organic frameworks. 相似文献
946.
Liu X Li Q Li R Li W Cheng J 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2011,84(1):68-73
Ab initio calculations have been performed for the complexes of benzene with HArF, HKrF, and HXeF. The computed results indicate that the complexes of benzene-HArF exist in different conformations and among them those with π-hydrogen bonds are the more stable than those with C-H···F hydrogen bonds. Interestingly, the Ar-H stretching frequency is redshifted in the more stable isomer and blueshifted in the less stable form. The Ng (Ng=Ar, Kr, and Xe) atomic number dependence of the Ng-H···π and C-H···F hydrogen bonds has been explored. The result indicates that the strength of Ng-H···π and C-H···F hydrogen bonds is weakened with the increase of Ng atomic number. Natural bond orbital analysis has been performed to understand the interaction nature, frequency shift of H-Ng stretch, and dependence of Ng-H···π and C-H···F hydrogen bonds on the Ng atomic number. 相似文献
947.
Ling-Bin Kong Mao-Cheng Liu Jun-Wei Lang Min Liu Yong-Chun Luo Long Kang 《Journal of Solid State Electrochemistry》2011,15(3):571-577
A new porous cobalt hydroxide film has been successfully electrodeposited on nickel foam from 0.1?M cobalt nitrate electrolyte at ?1.0?V vs. SCE without adding any surfactant. The microstructure and surface morphology of prepared cobalt hydroxide films were physically characterized by X-ray diffraction analysis and scanning electron microscopy. The results indicate that an interlaced network structure was obtained. The effects of electrodeposition time, deposition potential, and different substrates on the specific capacitance and microstructure of prepared porous ??-Co(OH)2 thin film were systematically studied. The results indicate that the film deposited on nickel foam at ?1.0?V has excellent electrochemical properties. A maximum specific capacitance of 1473?F?g?1 could be achieved at a current density of 2?A?g?1. 相似文献
948.
949.
950.
Gang Li Suling Yang Lingbo Qu Ran Yang Jianjun Li 《Journal of Solid State Electrochemistry》2011,15(1):161-166
A Nafion/multi-wall carbon nanotubes (MWNT) composite film-modified electrode was fabricated. The modified electrode showed
excellent electrocatalytic activity toward ascorbic acid (AA) and uric acid (UA) in 0.1-mol L−1 NaCl medium (pH 6.5). Compared to the bare electrode that only displayed a broad and overlapped oxidation peak, the Nafion/MWNT
film-modified electrode not only remarkably enhanced the anodic peak currents of AA and UA but also avoided the overlapping
of the anodic peaks of AA and UA with a 320-mV separation of both peaks. Under the optimized conditions, the peak currents
of AA and UA were proportional to their concentration at the ranges of 8.0 × 10−5 to 6.0 × 10−3 mol L−1 and 6.0 × 10−7 to 8.0 × 10−5 mol L−1, respectively. The proposed method was used for the detection of AA and UA in real samples with satisfactory results. 相似文献