全文获取类型
收费全文 | 48489篇 |
免费 | 1532篇 |
国内免费 | 690篇 |
专业分类
化学 | 22932篇 |
晶体学 | 490篇 |
力学 | 5083篇 |
综合类 | 430篇 |
数学 | 7844篇 |
物理学 | 13932篇 |
出版年
2023年 | 634篇 |
2022年 | 912篇 |
2021年 | 1443篇 |
2020年 | 1705篇 |
2019年 | 1117篇 |
2018年 | 1271篇 |
2017年 | 1962篇 |
2016年 | 1891篇 |
2015年 | 1997篇 |
2014年 | 2587篇 |
2013年 | 3641篇 |
2012年 | 2740篇 |
2011年 | 2471篇 |
2010年 | 2279篇 |
2009年 | 2208篇 |
2008年 | 1722篇 |
2007年 | 2067篇 |
2006年 | 2179篇 |
2005年 | 1711篇 |
2004年 | 1218篇 |
2003年 | 1288篇 |
2002年 | 1220篇 |
2001年 | 1462篇 |
2000年 | 786篇 |
1999年 | 1244篇 |
1998年 | 819篇 |
1997年 | 633篇 |
1996年 | 523篇 |
1995年 | 275篇 |
1994年 | 224篇 |
1993年 | 178篇 |
1992年 | 193篇 |
1991年 | 166篇 |
1990年 | 170篇 |
1989年 | 157篇 |
1988年 | 172篇 |
1986年 | 133篇 |
1985年 | 299篇 |
1984年 | 336篇 |
1983年 | 212篇 |
1982年 | 253篇 |
1981年 | 255篇 |
1980年 | 264篇 |
1979年 | 250篇 |
1978年 | 206篇 |
1977年 | 174篇 |
1976年 | 159篇 |
1975年 | 168篇 |
1974年 | 164篇 |
1973年 | 154篇 |
排序方式: 共有10000条查询结果,搜索用时 339 毫秒
51.
Ben Jadi S. El Guerraf A. Bazzaoui E.A. Wang R. Martins J.I. Bazzaoui M. 《Journal of Solid State Electrochemistry》2019,23(8):2423-2433
Journal of Solid State Electrochemistry - Due to their distinctive chemical, electronic, and environmental properties, polypyrrole is used as a blocking barrier for methanol leakage in direct... 相似文献
52.
Gunes Sibel Senyigit Ercan Karakaya Ersin Ozceyhan Veysel 《Journal of Thermal Analysis and Calorimetry》2019,136(4):1795-1806
Journal of Thermal Analysis and Calorimetry - This work introduces the determination of the optimum values of the design parameters in a tube with loose-fit perforated twisted tapes. The effects of... 相似文献
53.
54.
55.
The behaviors of ferromagnetic transition metals of the first period: Fe, Co and Ni are examined within density functional theory calculations in two dimensional carbon extended networks using model structure LiC6. Around geometry optimized structures, the energy-volume equations of states considering non magnetic and spin polarized configurations established ferromagnetic ground states with magnetizations –reduced with respect to the metals’– of 2 μB for FeC6 and 1 μB for CoC6 while no magnetic solution could be identified for NiC6. In the D6h point group of the P6/mmm space group lm decomposition of the d states results with increasing energy into doublet state E1g with d(x2-y2) and d(xy); singlet state A1g d(z2) and doublet state E2g d(xz) and d(yz) lying on EF and responsible of the onset of magnetic moments. This was mirrored via molecular orbital approach with a construct of Fe embedded between two extended carbon networks thus validating the model structure proposed for TC6 compounds. The 100% polarization in one spin channel allows proposing potential uses in spintronics applications. 相似文献
56.
Hierarchical motion planning at the acceleration level based on task priority matrix for space robot
Nonlinear Dynamics - A capacitive micromachined ultrasonic transducer (CMUT) due to many benefits is being considered as an imaging and therapeutic technology recently. The critical challenge is to... 相似文献
57.
Avramenko Andriy A. Shevchuk Igor V. Dmitrenko Nataliia P. Skitsko Ivan F. 《Journal of Thermal Analysis and Calorimetry》2022,147(22):12709-12719
Journal of Thermal Analysis and Calorimetry - The paper focuses on the analytical analysis of the propagation of a normal shock wave in an adiabatic gas flow with nanoparticles. A modified... 相似文献
58.
Periodica Mathematica Hungarica - We present a tight parametrical Hermite–Hadamard type inequality with probability measure, which yields a considerably closer upper bound for the mean value... 相似文献
59.
Excessive consumption of substances such as food colorants, exposure to doses of metal ions, antibiotic residues and pesticides residues above maximum tolerance limit have a detrimental effect on human health. Hence in detecting these harmful substances, the development of sensitive, selective and convenient analytical tools is an essential step. Graphene and graphene like 2D graphitic carbon nitride have shown great promise in the development of electrochemical sensors for determining the levels of these substances in different samples. In this paper, graphene and graphene like 2D graphitic carbon nitride applications on the determination of various food colorants in foods and drinks such as azo dyes (tartrazine, allura red, amaranth, carmine and sunset yellow); metal ions contaminants, antibiotic and pesticide residues in the environment are reviewed. 相似文献
60.
Over the past two decades, advanced materials with hollow interiors have received significant attention in materials research owing to their great application potential across a vast number of technological fields. Though with great difficulty, multi-shelled hollow metal–organic frameworks (MSHMs) have also been successfully synthesized in recent years. Herein, a rational shell-by-shell soft-templating protocol has been devised to fabricate highly uniform multi-shelled hollow cobalt-imidazole-based MOF (ZIF-67). For the first time, it has become possible to endow mesoporosity to this new type of functional material (i.e., mesoporous MOFs). When used as carrier materials in catalytic reactions, in principle, these mesoporous MSHMs with high surface area not only improve the dispersity of metal nanoparticles (NPs), but also efficiently facilitate the mass diffusion of the reactions, resulting in enhanced catalyst activity. Moreover, the obtained MSHMs/M nanocomposites serve as base-metal bifunctional catalysts for one-pot oxidation-Knoevenagel condensation cascade reaction, in which the MSHMs itself serves as a pristine active catalyst in addition to its role of catalyst support. The results demonstrate that excellent multifunctional catalysts can be achieved via preparing intrinsically microporous bulk MOFs into extrinsically mesoporous MSHMs which possess many structural merits that conventional bulk MOFs do not have. 相似文献