全文获取类型
收费全文 | 21569篇 |
免费 | 3524篇 |
国内免费 | 2431篇 |
专业分类
化学 | 15393篇 |
晶体学 | 269篇 |
力学 | 1335篇 |
综合类 | 196篇 |
数学 | 2145篇 |
物理学 | 8186篇 |
出版年
2024年 | 79篇 |
2023年 | 519篇 |
2022年 | 746篇 |
2021年 | 837篇 |
2020年 | 903篇 |
2019年 | 848篇 |
2018年 | 723篇 |
2017年 | 674篇 |
2016年 | 1030篇 |
2015年 | 1020篇 |
2014年 | 1152篇 |
2013年 | 1508篇 |
2012年 | 1942篇 |
2011年 | 1971篇 |
2010年 | 1306篇 |
2009年 | 1138篇 |
2008年 | 1325篇 |
2007年 | 1313篇 |
2006年 | 1155篇 |
2005年 | 1020篇 |
2004年 | 731篇 |
2003年 | 640篇 |
2002年 | 577篇 |
2001年 | 439篇 |
2000年 | 418篇 |
1999年 | 488篇 |
1998年 | 362篇 |
1997年 | 374篇 |
1996年 | 317篇 |
1995年 | 302篇 |
1994年 | 307篇 |
1993年 | 249篇 |
1992年 | 202篇 |
1991年 | 201篇 |
1990年 | 179篇 |
1989年 | 113篇 |
1988年 | 88篇 |
1987年 | 90篇 |
1986年 | 60篇 |
1985年 | 46篇 |
1984年 | 43篇 |
1983年 | 24篇 |
1982年 | 25篇 |
1981年 | 18篇 |
1980年 | 14篇 |
1979年 | 1篇 |
1975年 | 2篇 |
1957年 | 4篇 |
1936年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 8 毫秒
71.
Fabrication of hexaphenylsilole nanowires and their morphology-tunable photoluminescence. 总被引:1,自引:0,他引:1
Liping Heng Jin Zhai Anjun Qin Yuqi Zhang Yongqiang Dong Ben Zhong Tang Lei Jiang 《Chemphyschem》2007,8(10):1513-1518
Immersion of nanoporous alumina membranes into saturated solutions of hexaphenylsilole with subsequent solvent evaporation affords aligned organic nanowires. The luminescent properties of the hexaphenylsilole nanowires can be manipulated by varying their morphologies, which were controlled by changing the channel sizes of the alumina templates. 相似文献
72.
73.
甲烷部分氧化制合成气 Ⅰ.甲烷在过渡金属上的活化 总被引:1,自引:0,他引:1
文中用同位素交换(D_2─CH_4)反应来测量四种过渡金属负载型催化剂对甲烷的活化能力,并与Svensson等从头算的计算结果作了比较,表明最有效活化甲烷分子的C─H键的金属是铑(Rh).文中还测定了在甲烷部分氧化制合成气反应中,四个不同催化剂的催化活性与选择性,并与它们对甲烷的活化能力进行对比,可以看出甲烷部分氧化反应中,反应活性高的催化剂有效地活化甲烷,断裂C─H键,而且氘代甲烷产物分布以形成CD_4产物为主要成份. 相似文献
74.
Jiang Zhankui A. Persson L. Sturesson S. Svanberg 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1991,21(4):315-322
In the recently introduced high-contrast transmission version of saturated absorption laser spectroscopy, narrow signals are obtained from dense atomic samples subject to strong pumping. A study of possible systematic shifts of the signals in this domain of rather extreme experimental conditions was performed in order to assess the validity of spectroscopic data obtained with this technique. Certain signal components were found to be slightly shifted while others were not. Further, a theoretical study of the behaviour of overlapping signals in the high-contrast regime is presented. In particular, the question of whether structures buried under the natural linewidth could be resolved is addressed. 相似文献
75.
ICP激发光源以其独特的功能使ICP/AES技术在稀土分析中的应用日益广泛,在一定程度上取代了经典的直流电弧光谱法,但应指出,由于常规雾化器的低雾化效率(≤5%)和试样的高倍稀释,ICP/AES技术的实际检测能力的改善并不明显,本文用ICP光谱法测定了 相似文献
76.
Nicole Fietkau Fran?ois G Chevallier Li Jiang Timothy G J Jones Richard G Compton 《Chemphyschem》2006,7(10):2162-2167
The size of a glass sphere positioned in the center of a microdisk electrode is determined by using a simple electrochemical procedure and is confirmed, additionally, by a microscopical measurement of the sphere at the time of the electrochemical measurement. The cyclic voltammetric response of the naked electrode and of the electrode with the sphere positioned in its center is recorded over a wide range of scan rates (0.002-1.5 V s(-1)). The size of the sphere is then determined by comparison of the experimental voltammogram with simulations for each individual scan rate. 相似文献
77.
Huang M Jin Y Jiang H Sun X Chen H Liu B Wang E Dong S 《The journal of physical chemistry. B》2005,109(32):15264-15271
Multiple-deposited Pt overlayer modified Pt nanoparticle (MD-Pt overlayer/PtNPs) films were deliberately constructed on glassy carbon electrodes through alternately multiple underpotential deposition (UPD) of Ag followed redox replacement reaction by Pt (II) cations. The linear and regular growth of the films characterized by cyclic voltammetry was observed. Atomic force spectroscopy (AFM) provides the surface morphology of the nanostructured Pt films. Rotating disk electrode (RDE) voltammetry and rotating ring-disk electrode (RRDE) voltammetry demonstrate that the MD-Pt overlayer/PtNPs films can catalyze an almost four-electron reduction of O(2) to H(2)O in air-saturated 0.1 M H(2)SO(4). Thus-prepared Pt films behave as novel nanostructured electrocatalysts for dioxygen reduction and hydrogen evolution reaction (HER) with enhanced electrocatalytic activities, in terms of both reduction peak potential and peak current, when compared to that of the bulk polycrystalline Pt electrode. Additionally, it is noted that after multiple replacement cycles, the electrocatalytic activities improved remarkably, although the increased amount of Pt is very low in comparison to that of pre-modified PtNPs due to the intrinsic feature of the UPD-redox replacement technique. In other words, the electrocatalytic activities could be improved markedly without using very much Pt by the technique of tailoring the catalytic surface. These features may provide an interesting way to produce Pt catalysts with a reliable catalytic performance as well as a reduction in cost. 相似文献
78.
A method is proposed to calculate molar conductivity based on mode coupling theory in which the ion transference number is introduced into the theory. The molar conductivities of LiPF6, LiClO4, LiBF4, LiAsF6 in PC (propylene carbonate) are calculated based on this method. The results fit well to the literature data. This presents a potential way to calculate the conductivities of Li-ion battery electrolytes. 相似文献
79.
80.
Shuang‐Jun Lin Chang‐Heng Tan Shan‐Hao Jiang Yi‐Ming Li Da‐Yuan Zhu 《Helvetica chimica acta》2006,89(11):2789-2793
Four new iridoids, buergerinins B–E ( 1 – 4 ), along with three known iridoids, were isolated from the roots of Scrophularia buergeriana. Their structures were identified on the basis of spectroscopic analysis. 相似文献