全文获取类型
收费全文 | 106008篇 |
免费 | 18145篇 |
国内免费 | 10170篇 |
专业分类
化学 | 71737篇 |
晶体学 | 1225篇 |
力学 | 6967篇 |
综合类 | 540篇 |
数学 | 11980篇 |
物理学 | 41874篇 |
出版年
2024年 | 372篇 |
2023年 | 2154篇 |
2022年 | 3688篇 |
2021年 | 3908篇 |
2020年 | 4298篇 |
2019年 | 4182篇 |
2018年 | 3585篇 |
2017年 | 3308篇 |
2016年 | 5216篇 |
2015年 | 4994篇 |
2014年 | 6066篇 |
2013年 | 7830篇 |
2012年 | 9489篇 |
2011年 | 9827篇 |
2010年 | 6481篇 |
2009年 | 6189篇 |
2008年 | 6580篇 |
2007年 | 6018篇 |
2006年 | 5502篇 |
2005年 | 4604篇 |
2004年 | 3414篇 |
2003年 | 2679篇 |
2002年 | 2416篇 |
2001年 | 1982篇 |
2000年 | 1768篇 |
1999年 | 2074篇 |
1998年 | 1848篇 |
1997年 | 1723篇 |
1996年 | 1890篇 |
1995年 | 1503篇 |
1994年 | 1462篇 |
1993年 | 1165篇 |
1992年 | 1070篇 |
1991年 | 984篇 |
1990年 | 791篇 |
1989年 | 563篇 |
1988年 | 464篇 |
1987年 | 384篇 |
1986年 | 376篇 |
1985年 | 318篇 |
1984年 | 241篇 |
1983年 | 157篇 |
1982年 | 142篇 |
1981年 | 107篇 |
1980年 | 76篇 |
1979年 | 44篇 |
1978年 | 34篇 |
1976年 | 36篇 |
1975年 | 33篇 |
1974年 | 45篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
JPC – Journal of Planar Chromatography – Modern TLC - A new high-performance thin-layer chromatographic (HPTLC) method has been developed for the simultaneous estimation of... 相似文献
42.
43.
44.
在中国科学技术大学夏季学期的研究型实验课程"化学科研基础训练"中开设"壳聚糖的制备与表征"综合实验,以龙虾壳为原料,通过除蛋白、脱盐、脱色、脱乙酰等一系列反应,制备得到目标产物壳聚糖。运用红外光谱、核磁共振仪、黏度法、滴定等对产品的结构及性能进行表征。 相似文献
45.
46.
We investigate terahertz radiation(T-rays) from a pentacene organic diode at room temperature. The quantum chemistry calculation for frequency-related Huang–Rhys factor of pentacene is also carried out. The results demonstrate that the T-rays can come from a bending vibration of pentacene skeleton after the energy of pentacene exciton transferring to the vibrational excited state via electron–phonon coupling. Frequency and natural bond orbital analytics of pentacene and its derivatives are performed in order to explain the result and develop new materials to get higher emission. This work provides a new way to produce T-rays with a simple device at room temperature. 相似文献
47.
S. Q. Hou W. Wang Z. Y. Wang Z. W. Hu K. Liu 《Journal of Applied Mechanics and Technical Physics》2018,59(1):153-162
In order to investigate the characteristics of force chains in a granular flow system, a parallel plate shear cell is constructed to simulate the shear movement of an infinite parallel plate and observe variations in relevant parameters. The shear dilatancy process is divided into three stages, namely, plastic strain, macroscopic failure, and granular recombination. The stickslip phenomenon is highly connected with the evolution of force chains during the shear dilatancy process. The load–distribution rate curves and patterns of the force chains are utilized to describe the load-carrying behaviors and morphologic changes of force chains separately. Force chains, namely, “diagonal gridding,” “tadpole-shaped,” and “pinnate” are defined according to the form of the force chains in the corresponding three stages. 相似文献
48.
49.
50.
Youchao Wang Na Tian Weize Sun Boerhan Rena Xusheng Guo Yang Feng Chao Li Xuesong Wang Qianxiong Zhou 《Particle & Particle Systems Characterization》2020,37(5):2000045
Photoactivated chemotherapy (PACT) has appealing merits over traditional chemotherapy as well as photodynamic therapy (PDT) by virtue of its spatial and temporal control on drug activity and oxygen-independent mechanisms of action. However, the short photoactivation wavelengths, e.g., visible light–activated Ru(II)-based PACT agents, limit the clinical application severely. In this work, a facile construction of supramolecular nanoparticles from a poly(ethylene glycol) (PEG)-modified [Ru(dip)2(py-SO3)]+ (abbreviated as Ru-PEG, dip = 4,7-diphenyl-1,10-phenanthroline, py-SO3 = pyridine-2-sulfonate) and 1,3-phenylenebis(pyren-1-ylmethanone) (BP) is shown. While Ru-PEG may undergo photoinduced ligand dissociation and release anticancer species of [Ru(dip)2(H2O)2]2+, BP has extremely large two-photon absorption cross sections (δ2) in the NIR region and intense fluorescence over the wavelengths where Ru-PEG has strong absorption. Thus, two-photon excitation of BP followed by an efficient Förster resonance energy transfer (FRET) from BP to Ru-PEG may lead to a potent inactivation against cisplatin-resistant cancer cells and 3D multicellular tumor spheroids (MCTSs). The residue fluorescence of BP also allows the cellular uptake of the particles to be visualized. This work provides a universal and convenient strategy to realize theranostic PACT in the ideal phototherapeutic window of 650–900 nm. 相似文献