全文获取类型
收费全文 | 119610篇 |
免费 | 8237篇 |
国内免费 | 6722篇 |
专业分类
化学 | 55684篇 |
晶体学 | 1459篇 |
力学 | 9182篇 |
综合类 | 444篇 |
数学 | 36377篇 |
物理学 | 31423篇 |
出版年
2024年 | 95篇 |
2023年 | 772篇 |
2022年 | 1314篇 |
2021年 | 1544篇 |
2020年 | 1739篇 |
2019年 | 1765篇 |
2018年 | 11606篇 |
2017年 | 11464篇 |
2016年 | 7987篇 |
2015年 | 3010篇 |
2014年 | 2974篇 |
2013年 | 3773篇 |
2012年 | 7840篇 |
2011年 | 14533篇 |
2010年 | 8575篇 |
2009年 | 9015篇 |
2008年 | 9867篇 |
2007年 | 11526篇 |
2006年 | 2880篇 |
2005年 | 3479篇 |
2004年 | 3128篇 |
2003年 | 3244篇 |
2002年 | 2345篇 |
2001年 | 1334篇 |
2000年 | 1199篇 |
1999年 | 914篇 |
1998年 | 765篇 |
1997年 | 653篇 |
1996年 | 650篇 |
1995年 | 530篇 |
1994年 | 476篇 |
1993年 | 399篇 |
1992年 | 304篇 |
1991年 | 275篇 |
1990年 | 249篇 |
1989年 | 179篇 |
1988年 | 180篇 |
1987年 | 153篇 |
1986年 | 161篇 |
1985年 | 124篇 |
1984年 | 89篇 |
1983年 | 73篇 |
1982年 | 74篇 |
1981年 | 66篇 |
1980年 | 62篇 |
1979年 | 68篇 |
1978年 | 51篇 |
1914年 | 46篇 |
1912年 | 41篇 |
1909年 | 42篇 |
排序方式: 共有10000条查询结果,搜索用时 218 毫秒
41.
Journal of Thermal Analysis and Calorimetry - A complete analysis of the thermal process about melamine was presented, in which different methods were applied to determine the characteristic of the... 相似文献
42.
随着经济的飞速发展,社会对能源的需求日益扩大,对工业废水的无害化处理也提出了更高的要求。光催化燃料电池 (photocatalytic fuel cell, PFC) 在燃料电池中引入半导体光催化材料作为电极,实现了有机污染物高效降解和同步对外产电的双重功能,在废水无害化与资源化利用方面具有潜在的应用价值。半导体光催化电极是PFC系统高效运行的核心组件,增强其可见光响应和光生载流子分离是提高PFC性能的关键策略。反应器结构设计和运行参数优化也有利于改善PFC性能。本文从PFC基本原理和应用入手,综述了PFC在环境污染物资源化处理中的研究进展,并详细阐述了提高PFC的污染控制性能和产电效率的优化手段,为进一步设计高效稳定的PFC系统并实现其在水污染控制和清洁能源生产中的应用提供理论指导。 相似文献
43.
Luo Dajuan Liu Bingqian Gao Rong Su Lixia Su Yonghuan 《Journal of Solid State Electrochemistry》2022,26(3):749-759
Journal of Solid State Electrochemistry - Cortisol, a steroid hormone, has been confirmed as a kind of biomarker that reflects the stress response of psychobiology and related adverse health... 相似文献
44.
45.
A protocol to correct for intra‐ and interspecific variation in tail hair growth to align isotope signatures of segmentally cut tail hair to a common time line 下载免费PDF全文
46.
Aequationes mathematicae - We discuss equivalence conditions for the non-existence of non-trivial meromorphic solutions to the Fermat Diophantine equation $$f^m(z)+g^n(z)=1$$ with integers $$m,n\ge... 相似文献
47.
S. V. Panin I. V. Vlasov V. P. Sergeev B. B. Ovechkin P. O. Marushchak Sunder Ramasubbu P. S. Lyubutin V. V. Titkov 《Physical Mesomechanics》2015,18(3):261-272
The structure and properties of 12Cr1MoV steel irradiated with a zirconium ion beam were studied by optical microscopy, scanning electron microscopy, and micro- and nanoindentation. It is shown that the modification covers the entire cross-section of the irradiated specimens to a depth of 1 mm. The data on irradiation-induced structural changes are used to interpret the changes in mechanical properties of the irradiated specimens under static and cyclic loading. Particular attention is given to analysis of strain estimation by the digital image correlation method. 相似文献
48.
He Haidong Yang Haifeng Zhou Longpeng Chen Tianchi 《Journal of Russian Laser Research》2015,36(3):292-299
Ni–Co alloys have a wide range of applications in various fields owning to their excellent physical, chemical, and mechanical properties. In this paper, we prepare Ni–Co alloy coatings on 316L stain steel surfaces by electroplating. We present a novel approach utilizing a nanosecond laser to induce microtextures on Ni–Co alloy coatings. We study experimentally the effects of laser power and scanning rate on the surface morphologies of Ni–Co alloy coatings. The results indicate that the shape and size of induced microtextures can be controlled by the laser power and scanning rate. The size of grains increases with increase in the work current of the laser (WCL) at a certain scanning rate. With the WCL constant, the size of grains decreases with increase in scanning rate while their average height increases. It is a simple and easily-controlled method for the fabrication of microstructures on Ni–Co alloy coatings, which has promising applications in investigations of the properties of microtextured surfaces, such as friction, adhesion, and wetting. 相似文献
49.
50.
Solid‐state 31P NMR investigation on the status of guanine nucleotides in paclitaxel‐stabilized microtubules 下载免费PDF全文
Ga Hyang Lee Su Young Oh Kwon Joo Yeo Taslima Ferdous Meeyeon Cho Younkee Paik 《Magnetic resonance in chemistry : MRC》2015,53(5):330-336
Microtubule dynamics is a target for many chemotherapeutic drugs. In order to understand the biochemical effects of paclitaxel on the GTPase activity of tubulin, the status of guanine nucleotides in microtubules was investigated by 31P cross‐polarization magic angle spinning (CPMAS) NMR. Microtubules were freshly prepared in vitro in the presence of paclitaxel and then lyophilized in sucrose buffer for solid‐state NMR experiments. A 31P CPMAS NMR spectrum with the SNR of 25 was successfully acquired from the lyophilized microtubule sample. The broadness of the 31P spectral lines in the spectrum indicates that the molecular environments around the guanine nucleotides inside tubulin may not be as crystalline as reported by many diffraction studies. Deconvolution of the spectrum into four spectral components was carried out in comparison with the 31P NMR spectra obtained from five control samples. The spectral analysis suggested that about 13% of the nucleotides were present as GTP and 37% as GDP in the β‐tubulin (E‐site) of the microtubules. It was found that most of the GDPs were present as GDP‐Pi complex in the microtubules, which seems to be one of the effects of paclitaxel binding. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献