全文获取类型
收费全文 | 81948篇 |
免费 | 9215篇 |
国内免费 | 8991篇 |
专业分类
化学 | 45974篇 |
晶体学 | 986篇 |
力学 | 4078篇 |
综合类 | 801篇 |
数学 | 17868篇 |
物理学 | 30447篇 |
出版年
2024年 | 152篇 |
2023年 | 2387篇 |
2022年 | 2602篇 |
2021年 | 3476篇 |
2020年 | 3944篇 |
2019年 | 2616篇 |
2018年 | 3090篇 |
2017年 | 3781篇 |
2016年 | 3952篇 |
2015年 | 4345篇 |
2014年 | 5805篇 |
2013年 | 7485篇 |
2012年 | 7286篇 |
2011年 | 6939篇 |
2010年 | 5904篇 |
2009年 | 5884篇 |
2008年 | 4116篇 |
2007年 | 4639篇 |
2006年 | 4150篇 |
2005年 | 2603篇 |
2004年 | 1610篇 |
2003年 | 1551篇 |
2002年 | 1352篇 |
2001年 | 1756篇 |
2000年 | 889篇 |
1999年 | 1334篇 |
1998年 | 908篇 |
1997年 | 667篇 |
1996年 | 458篇 |
1995年 | 408篇 |
1994年 | 338篇 |
1993年 | 319篇 |
1992年 | 300篇 |
1991年 | 277篇 |
1990年 | 285篇 |
1989年 | 218篇 |
1988年 | 101篇 |
1987年 | 122篇 |
1986年 | 96篇 |
1985年 | 174篇 |
1984年 | 189篇 |
1983年 | 132篇 |
1982年 | 148篇 |
1981年 | 152篇 |
1980年 | 121篇 |
1979年 | 122篇 |
1978年 | 99篇 |
1977年 | 91篇 |
1976年 | 84篇 |
1975年 | 79篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
1.
以氧化石墨烯(GO)为原料, 利用温和方法制备了3种不同还原程度的部分还原氧化石墨烯pRGO1, pRGO2和pRGO3(pRGO1—3); 利用傅里叶变换红外光谱(FTIR)、 拉曼光谱(Raman)、 X 射线光电子能谱(XPS)、 紫外-可见光谱(UV-Vis)、 透射电子显微镜(TEM)和 EDS能谱对其结构和形貌进行了表征. 细胞实验结果表明, 无激光照射下pRGO1—3本身的细胞毒性较低; 近红外(NIR)激光照射下pRGO1—3通过光热和光毒性双重作用杀伤肿瘤细胞. 实验结果显示了pRGO 在肿瘤光热疗法和光动力疗法领域的应用潜力. 相似文献
2.
Zhihong Zhao Bin Wang Rui Tan Wenjing Liu Minghui Zhang 《Magnetic resonance in chemistry : MRC》2022,60(4):427-433
In this study, the transverse relaxation time (T2) of activated carbon (AC) in different relative environment humidity was detected firstly by low-field nuclear magnetic resonance (LFNMR). The pore size (diameter) of AC distributions was calculated by the relationship between T2 and surface relaxation rate (ρ), where ρ was obtained by the detection of nine porous materials with known pore size. The results showed that the pore size distributions of AC calculated by ρ < 0.19 nm/ms were in good agreement with that obtained by nitrogen adsorption method and proved that LFNMR as a new detection method was feasible for characterizing AC pore size distribution. 相似文献
3.
Yuanbo Gao Tingting Yang Xueli Wang Jizong Chen Yong He 《Journal of polymer science. Part A, Polymer chemistry》2022,60(10):1610-1623
Two series of novel alternating copolyoxamides (PAnT-alt-n2 and PAn2-alt-62) are synthesized via solution/solid-state polycondensation (SSP). The alternating structures are analyzed carefully with 1H NMR and 13C NMR spectra. The melting behaviors, thermal stabilities, crystal structures and crystallinities are systematically evaluated by DSC, TGA and WAXD. The results reveal that these alternating copolyoxamides possess almost perfect alternating chain structures and have high melting temperature (Tm > 270 °C), high crystallinity (Xc > 32%) and high decomposition temperature (T5 > 405 °C) as well as low saturated water absorption (<3.5 wt%), which suggests that they have high potential as engineering plastic of high heat resistant. 相似文献
4.
5.
Acta Mechanica Sinica - 相似文献
6.
Journal of Applied Spectroscopy - The present work aims to focus on the synthesis and spectral studies of the charge-transfer interaction between the nitro organic acceptors molecules [e.g.,... 相似文献
7.
Tian Xiu-Zhi Yang Rui Ma Jia-Jia Ni Yong-Hao Deng Hai-Bo Dai Lei Tan Jiao-Jun Zhang Mei-Yun Jiang Xue 《高分子科学》2022,40(7):789-798
Chinese Journal of Polymer Science - Antistatic and strength properties are of vital importance for polyurethane rubber used in moving parts of many industrial instruments. Herein, polyurethane was... 相似文献
8.
9.
《Journal of Saudi Chemical Society》2022,26(3):101470
There would be a major effect on the cartilage regeneration characteristics of ceramic material in a substrate implant requiring biologically active biomaterials and the reinforcement phase. At this moment, we produced collagen-hyaluronic acid @ hydroxyapatite-halloysite nanotube-single walled carbon nanotube composites, which is a successful technique for making a scaffold with a superior counter for cartilage property. FTIR, XRD, and SEM-EDAX were used to perform morphological and structural studies. The prepared composite's surface feature was investigated and discovered by HRTEM-SAED analysis, and it observed porous nature. The simulated body fluids (SBF) assessment of the materials was noticed their bioactivity and chondrocytes to determine their biocompatibility. Hybrid composite displayed promise for cartilage tissue engineering despite mesenchymal stem cells compatibility effect and magnificently demonstrated an antibacterial effect without antibiotics. The live/dead cells analysis shows that the composite can significantly improve mesenchymal stem cells, and the composite has the potential ability for cartilage regeneration. The above characteristics make the material quite interesting and important in the area for regenerative medicinal uses. 相似文献
10.
Hao Lu Xiaodong Wang Hang Wang Andong Zhang Xinming Zheng Na Yu Zheng Tang Xinjun Xu Yahui Liu Ya-Nan Chen Zhishan Bo 《中国科学:化学(英文版)》2022,65(3):594-601
Three nonfused ring electron acceptors (NFREAs) TTC6,TT-C8T and TT-TC8 were purposefully designed and synthesized.The molecular geometry can be adjusted by the steric hindrance of lateral substituents.According to the DFT calculations,from TTC6 to TT-C8T and TT-TC8,planarity of the molecular backbone is gradually improved,accompanying with the enhancing of intramolecular charge transfer effect.As for TT-TC8,the two phenyl substituents are almost perpendicular to the molecular backbone,which endues the acceptor with good solubility and suppresses it to form over-aggregation.Multidirectional regular molecular orientation and closer molecular stacking are formed in TT-TC8 film.As a result,TT-TC8 based devices afford the highest PCE of 13.13%,which is much higher than that of TTC6 (4.41%) and TT-C8T (10.42%) and among the highest PCE values based on NFREAs. 相似文献