全文获取类型
收费全文 | 45269篇 |
免费 | 8738篇 |
国内免费 | 6886篇 |
专业分类
化学 | 33125篇 |
晶体学 | 709篇 |
力学 | 3001篇 |
综合类 | 497篇 |
数学 | 5212篇 |
物理学 | 18349篇 |
出版年
2024年 | 31篇 |
2023年 | 852篇 |
2022年 | 1168篇 |
2021年 | 1571篇 |
2020年 | 1861篇 |
2019年 | 1929篇 |
2018年 | 1642篇 |
2017年 | 1643篇 |
2016年 | 2265篇 |
2015年 | 2381篇 |
2014年 | 2908篇 |
2013年 | 3630篇 |
2012年 | 4364篇 |
2011年 | 4464篇 |
2010年 | 3355篇 |
2009年 | 3339篇 |
2008年 | 3551篇 |
2007年 | 2989篇 |
2006年 | 2821篇 |
2005年 | 2320篇 |
2004年 | 1693篇 |
2003年 | 1416篇 |
2002年 | 1433篇 |
2001年 | 1108篇 |
2000年 | 915篇 |
1999年 | 791篇 |
1998年 | 592篇 |
1997年 | 566篇 |
1996年 | 510篇 |
1995年 | 437篇 |
1994年 | 415篇 |
1993年 | 313篇 |
1992年 | 259篇 |
1991年 | 220篇 |
1990年 | 208篇 |
1989年 | 154篇 |
1988年 | 131篇 |
1987年 | 89篇 |
1986年 | 112篇 |
1985年 | 78篇 |
1984年 | 42篇 |
1983年 | 43篇 |
1982年 | 28篇 |
1981年 | 21篇 |
1980年 | 18篇 |
1979年 | 21篇 |
1977年 | 13篇 |
1975年 | 12篇 |
1972年 | 11篇 |
1925年 | 10篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
采用磁控溅射法在ITO玻璃上制备了CdZnTe薄膜,探究机械磨抛对CdZnTe薄膜阻变特性的影响。通过对XRD图谱、Raman光谱、AFM显微照片等实验结果分析阐明了机械磨抛影响CdZnTe薄膜阻变特性的物理机制。研究结果表明,磁控溅射制备的薄膜为闪锌矿结构,F43m空间群。机械磨抛提高了CdZnTe薄膜的结晶质量;CdZnTe薄膜粗糙度(Ra)由磨抛前的3.42 nm下降至磨抛后的1.73 nm;磨抛后CdZnTe薄膜透过率和162 cm-1处的类CdTe声子峰振动峰增强;CdZnTe薄膜的阻变开关比由磨抛前的1.2增加到磨抛后的4.9。机械磨抛提高CdZnTe薄膜质量及阻变特性的原因可能是CdZnTe薄膜在磨抛过程中发生了再结晶。 相似文献
2.
Rui Feng Zi-Ying Li Zhao-Quan Yao Zi-Ang Guo Yi-Nan Zhang Hao-Xiang Sun Wei Li Xian-He Bu 《中国科学:化学(英文版)》2022,65(1):128-134
The rational designability and chemical tunability of metal-organic frameworks(MOFs)are enabling tributes to efficaciously enhance their room temperature phosphorescence(RTP)performance.A family of stable anionic MOFs,[Zn2(4,5-ImDC)2]M2(NKU-132,M=(CH3)2NH2or(CH2CH3)2NH2),featuring significant RTP have been synthesized.By rational cation selection and in-situ replacement from dimethylammonium to diethylammonium,the phosphorescence lifetime is increased from 30.88 to126.3 ms,along with less sensitivity to air.This work provides an anti-quenching and lifetime tuning example for RTP-MOFmaterials via facile host-guest chemistry. 相似文献
3.
Acta Mathematicae Applicatae Sinica, English Series - A subset I of vertices of an undirected connected graph G is a nonseparating independent set (NSIS) if no two vertices of I are adjacent and G... 相似文献
4.
Nonlinear Dynamics - The perovskite solar cell (PSC) is one of the most promising photovoltaic candidates along with the highly increasing demand for green electricity. One of the main concerns... 相似文献
5.
6.
Yin Qingqing Xu Fen Sun Lixian Li Yaying Liao Lumin Wang Tao Guan Yanxun Xia Yongpeng Zhang Chenchen Wei Sheng Zhang Huanzhi Li Bin 《Journal of Thermal Analysis and Calorimetry》2022,147(12):6583-6592
Journal of Thermal Analysis and Calorimetry - Polyethylene glycol (PEG) is widely used as phase change materials (PCMs). However, the leakage and low thermal conductivity issues restrict its... 相似文献
7.
Zhi Sun Mengfan Zhao Lihua Zuo Shengnan Zhou Feng Fan Qingquan Jia Lianping Xue Hanbing Li Jian Kang Xiaojian Zhang 《Journal of separation science》2022,45(2):518-528
Juglandis Mandshuricae Cortex is the bark of Juglans mandshurica Maxim., which has been used as a folk medicine plant in China and India. In this study, an ultra-high performance liquid chromatography–quadrupole/orbitrap high-resolution mass spectrometry method was developed to clarify and quantify the chemical profiling of Juglandis Mandshuricae Cortex rapidly. A total of 113 compounds were characterized. Among them, seven flavonoids were simultaneously quantified in 15 min, including myricetin, myricetrin, taxifolin, kaempferol, quercetin, quercitrin, and naringenin. The method was validated for accuracy, precision, and the limits of detection and quantification. All calibration curves showed a good linear relationship (r > 0.9990) within test ranges. The intra- and inter-day relative standard deviations were less than 2.16%. Accuracy validation showed that the recovery was between 95.6 and 101.3% with relative standard deviation values below 2.85%. The validated method was successfully applied to determine the contents of seven flavones in Juglandis Mandshuricae Cortex from seven sources and the contents of these places were calculated respectively. This method provides a theoretical basis for further developing the medicinal value of Juglandis Mandshuricae Cortex. 相似文献
8.
Acta Mathematicae Applicatae Sinica, English Series - In this paper, we consider the statistical inferences in a partially linear model when the model error follows an autoregressive process. A... 相似文献
9.
10.
Journal of Algebraic Combinatorics - Highly nonlinear functions (bent functions, perfect nonlinear functions, etc.) on finite fields and finite (abelian or nonabelian) groups have been studied in... 相似文献