全文获取类型
收费全文 | 22832篇 |
免费 | 4094篇 |
国内免费 | 2917篇 |
专业分类
化学 | 16072篇 |
晶体学 | 255篇 |
力学 | 1499篇 |
综合类 | 188篇 |
数学 | 2550篇 |
物理学 | 9279篇 |
出版年
2024年 | 38篇 |
2023年 | 476篇 |
2022年 | 675篇 |
2021年 | 769篇 |
2020年 | 949篇 |
2019年 | 825篇 |
2018年 | 734篇 |
2017年 | 664篇 |
2016年 | 1073篇 |
2015年 | 1007篇 |
2014年 | 1263篇 |
2013年 | 1539篇 |
2012年 | 2037篇 |
2011年 | 2174篇 |
2010年 | 1417篇 |
2009年 | 1341篇 |
2008年 | 1530篇 |
2007年 | 1338篇 |
2006年 | 1351篇 |
2005年 | 1115篇 |
2004年 | 868篇 |
2003年 | 731篇 |
2002年 | 755篇 |
2001年 | 611篇 |
2000年 | 513篇 |
1999年 | 601篇 |
1998年 | 442篇 |
1997年 | 397篇 |
1996年 | 441篇 |
1995年 | 355篇 |
1994年 | 324篇 |
1993年 | 252篇 |
1992年 | 235篇 |
1991年 | 214篇 |
1990年 | 164篇 |
1989年 | 139篇 |
1988年 | 129篇 |
1987年 | 83篇 |
1986年 | 81篇 |
1985年 | 59篇 |
1984年 | 36篇 |
1983年 | 31篇 |
1982年 | 18篇 |
1981年 | 23篇 |
1980年 | 8篇 |
1979年 | 3篇 |
1978年 | 4篇 |
1966年 | 1篇 |
1957年 | 6篇 |
1936年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
Lithium-sulfur batteries (LSBs) with high energy density and low cost have been recognized as one of the most promising next-generation energy storage systems. Although it has taken decades of development, the practical application of LSBs has been hindered by several inherent obstacles, particularly the severe shuttle effect and sluggish reaction kinetics in the sulfur cathode. Various strategies have been proposed to address these problems via rational design of electrode materials and configurations. Freestanding sulfur cathode could be a promising strategy to improve the sulfur mass loading at the cathode level and energy density of LSBs. This minireview will briefly summary the recent advances in freestanding cathodes for LSBs. The advantages and disadvantages of various freestanding cathodes are discussed and the prospects for the development of flexible cathodes are envisioned. 相似文献
22.
Simultaneous quantitative determination of 20 active components in the traditional Chinese medicine formula Zhi‐Zi‐Da‐Huang decoction by liquid chromatography coupled with mass spectrometry: application to study the chemical composition variations in different combinations
下载免费PDF全文
![点击此处可从《Biomedical chromatography : BMC》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Zheng Tang Ran Yin Kaishun Bi Heyun Zhu Fei Han Kelin Chen Fenrong Wang 《Biomedical chromatography : BMC》2015,29(9):1406-1414
23.
Zhang Jia-Rui Zhang Jia-Qi Zheng Zhao-Lin Lin Da Shen Yu-Jia 《Nonlinear dynamics》2022,108(2):1005-1026
Nonlinear Dynamics - Parametrically excited oscillators are used in several domains, in particular to improve the dynamical behaviour of systems like in the case of the parametric amplification or... 相似文献
24.
Ionics - This study aims to explore the potential merits of palladium oxide sensing electrode. PdO is applied on a solid-state potentiometric sensor on an yttria-stabilized zirconia (YSZ)... 相似文献
25.
26.
Zheng Yuanzhou Yang Haoran Mazaheri Hossein Aghaei Alireza Mokhtari Namjoo Afrand Masoud 《Journal of Thermal Analysis and Calorimetry》2021,143(2):1425-1438
Journal of Thermal Analysis and Calorimetry - The purpose of this study is to numerically investigate flow field and turbulent heat transfer of hybrid nanofluid, water–DWCNT–TiO2 in a... 相似文献
27.
28.
Jiatian Chen Le Yang Ying Li Qinghua Hou Lanlan Li Peng Jin 《International journal of quantum chemistry》2019,119(16):e25961
Inorganic planar ring-shape molecules with 4n + 2 π electrons are always the focus of experimental synthesis and theoretical research due to their potential aromaticity and stability. In this work, the whole series of five-membered heterocycle monoanions X nY5-n− (X, Y = group 15 elements; n = 1-4) were thoroughly investigated by means of density functional theory calculations. They all have large formation energies and HOMO-LUMO gap energies, suggesting the potential thermodynamic and kinetic stability. Their aromaticities are comparable to that of typical aromatic hydrocarbons. Their thermal stabilities were firmly established by the ab initio molecular dynamics simulations. As most of them are predicted for the first time, their various spectra were simulated for experimental characterization. Furthermore, we demonstrate that these five-membered cyclic anions can be employed as η5-ligand to construct novel all-inorganic metallocenes, which may serve as the building blocks of low-dimensional nanomaterials. 相似文献
29.
Hejia Hu Linlin Wu Mei Li Cun Xue Guangcheng Wang Siying Chen Yong Huang Lin Zheng Aimin Wang Yueting Li Zipeng Gong 《Biomedical chromatography : BMC》2020,34(1):e4714
Eucommia ulmoides Oliv. (E. ulmoides) is a valuable and nourishing medicinal herb in China that has been used in the treatment of hypertension. Given the fact that most traditional Chinese medicine is mainly used to treat disease, investigating the pharmacokinetics of traditional Chinese medicines in the pathological state is more useful than that in the normal state. However, the differences in the absorption kinetics of active ingredients of E. ulmoides extract between pathological and physiological conditions have not been reported. Therefore, in this study, the rat intestinal in situ circulatory perfusion model was used to investigate the differences in absorption kinetics of seven active ingredients of E. ulmoides extract in normal and spontaneously hypertensive rats, namely, genipinic acid, protocatechuic acid, neochlorogenic acid, chlorogenic acid, cryptochlorogenic acid, (+)-pinoresinol di-O-β-D -glucopyranoside and (+)-pinoresinol 4′-O-β-D -glucopyranoside. Our results indicate that the pathological state of spontaneous hypertension may change the absorption of active components of E. ulmoides extracts, and these findings may provide a reference for improving the rational use of E. ulmoides in the clinic. 相似文献
30.
Dong Zheng Fu-Quan Wang Yuan-Guang Li Liang-Hong Guo Jing Cheng 《Analytica chimica acta》2004,508(2):225-231
Optimized combination of chemical agents was selected for sensitive electrochemical detection of dissolved ruthenium tris-(2,2′-bipyridine) (Ru-bipy). The detection was based on the chemical amplification mechanism, in which the anodic current of a redox-active analyte was amplified by a sacrificial electron donor in solution. On indium-doped tin oxide (ITO) electrodes, electrochemical reaction of the analyte was reversible, but that of the electron donor was greatly suppressed. Several transition metal complexes, such as ferrocene and tris-(2,2′-bipyridine) complexes of osmium, iron and ruthenium, were evaluated as model analyte. A correlation between the amplified current and the standard potential of the complex was observed, and Ru-bipy generated the largest current. A variety of organic bases, acids and zwitterions were assessed as potential electron donor. Sodium oxalate was found to produce the largest amplification factor. With Ru-bipy as the model analyte and oxalate as the electron donor, the analyte concentration curve was linear up to 50 μM, with a lower detection limit of approximately 50 nM. Preliminary work was presented in which a Ru-bipy derivative was attached to bovine serum albumin and detected electrochemically. Although the combination of Ru-bipy, oxalate and ITO electrode has been used before for electrochemiluminescent detection of Ru-bipy and oxalate, as well as electrochemical detection of oxalate, its utility in amplified voltammetric detection of Ru-bipy as a potential electrochemical label has not been reported previously. 相似文献