全文获取类型
收费全文 | 39983篇 |
免费 | 7172篇 |
国内免费 | 5342篇 |
专业分类
化学 | 29011篇 |
晶体学 | 547篇 |
力学 | 2494篇 |
综合类 | 484篇 |
数学 | 4609篇 |
物理学 | 15352篇 |
出版年
2024年 | 74篇 |
2023年 | 785篇 |
2022年 | 918篇 |
2021年 | 1283篇 |
2020年 | 1634篇 |
2019年 | 1595篇 |
2018年 | 1314篇 |
2017年 | 1282篇 |
2016年 | 1859篇 |
2015年 | 1900篇 |
2014年 | 2272篇 |
2013年 | 2887篇 |
2012年 | 3612篇 |
2011年 | 3842篇 |
2010年 | 2670篇 |
2009年 | 2539篇 |
2008年 | 2834篇 |
2007年 | 2606篇 |
2006年 | 2389篇 |
2005年 | 2046篇 |
2004年 | 1580篇 |
2003年 | 1281篇 |
2002年 | 1251篇 |
2001年 | 1013篇 |
2000年 | 861篇 |
1999年 | 874篇 |
1998年 | 682篇 |
1997年 | 696篇 |
1996年 | 593篇 |
1995年 | 534篇 |
1994年 | 520篇 |
1993年 | 401篇 |
1992年 | 304篇 |
1991年 | 327篇 |
1990年 | 282篇 |
1989年 | 188篇 |
1988年 | 156篇 |
1987年 | 149篇 |
1986年 | 104篇 |
1985年 | 77篇 |
1984年 | 70篇 |
1983年 | 50篇 |
1982年 | 50篇 |
1981年 | 35篇 |
1980年 | 29篇 |
1979年 | 6篇 |
1976年 | 6篇 |
1975年 | 10篇 |
1959年 | 5篇 |
1957年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 215 毫秒
31.
Hui Li Jian Liu Juan Zhao Huiting He Dr. Dabo Jiang Prof. Steven Robert Kirk Prof. Qiong Xu Dr. Xianxiang Liu Prof. Dulin Yin 《ChemistryOpen》2021,10(4):477-485
A series of tetraimidazolium salts with different anions was prepared and applied in the isomerization of β-pinene oxide. After examining the activity of different catalysts, a remarkable enhancement of the selectivity of perillyl alcohol (47 %) was obtained over [PEimi][HNO3]4 under mild reaction conditions and using DMSO as the solvent. Furthermore, noncovalent interactions between solvent molecules and the catalyst were found by FT-IR spectroscopy and confirmed by computational chemistry. The homogeneous catalyst showed excellent stability and was reused up to six times without significant loss. 相似文献
32.
33.
34.
Liming Fan Feng Wang Dongsheng Zhao Yuxin Peng Yuxin Deng Yinwei Luo Xiutang Zhang 《应用有机金属化学》2020,34(12):e5960
Guided by the self-penetrating features can improve the stability of metal organic frameworks (MOFs), an unprecedented 3D self-penetrated framework, {[Zn (tptc)0.5(bimb)]·H2O}n ( NUC-6 , here NUC corresponding to North University of China), with 3D (4,4)-c {86} net, was designed. Benefit from the high chemical stability and excellent luminescent property, NUC-6 can be act as an efficient multi-response chemo-sensor in detecting dichloronitroaniline pesticide and nitrofuran antibiotics in water with the detection limits are 116 ppb for DCN pesticide, 16 ppb for NFT antibiotic, and 12 ppb for NTZ antibiotic. Besides, the mechanisms of luminescence quenching were revealed from the viewpoint of internal filter effect (IFE) and photo-induced electron transfer (PET), implied by the optical spectroscopy and quantum chemical calculation. This work provides a promising strategy to design stable MOFs by improving the self-penetrating features and to expand their practical applications in the detection of organic pollutants in aqueous medium. 相似文献
35.
Jia Yang Xingang Li Wenjun Li Xin Xi Qian Du Feng Pan Songqing Liu 《Biomedical chromatography : BMC》2020,34(8):e4857
Because of its unpredictable side effects and efficacy, the anticancer drug docetaxel (DTX) requires improved characterisation of its pharmacokinetic profiles through population pharmacokinetic studies. A sensitive and rugged LC–MS/MS method for the detection of DTX in human plasma was developed and optimised using paclitaxel as an internal standard (IS). The plasma samples underwent rapid extraction using hybrid solid-phase extraction-protein precipitation. The analyte and IS were separated with an isocratic system on a Zorbax Eclipse Plus C18 column using water containing 0.05% acetic acid along with 20 μM of sodium acetate and methanol (30/70, v/v) as the mobile phase. Quantification was performed using a triple quadrupole mass spectrometer through multiple reaction monitoring in positive mode, using the m/z 830.3 → 548.8 and m/z 876.3 → 307.7 transitions for DTX and paclitaxel, respectively. The range of the calibration curve was 1–500 ng/mL for DTX, and the linear correlation coefficient was >0.99. The accuracies ranged from −4.6 to 4.2%, and the precision was no higher than 7.0% for the analytes. No significant matrix effect was observed. Both DTX and the IS showed considerable recovery. This method was finally applied to the establishment of a population pharmacokinetic model to optimise the clinical use of DTX. 相似文献
36.
37.
38.
In this Letter,a novel system for adaptively correcting the phase of a dynamic multimode beam is proposed.While using merely one spatial light modulator,the phase measurement of the first-order diffraction pattern and the correction of the zeroth diffraction order are simultaneously realized.The real-time experimental result is obtained at a control rate of 10 Hz.The power-in-the-bucket value is improved from 38.5%to 61.8%,even with fundamental mode content that is consistently below 30%.To the best of our knowledge,this is the first implementation of real-time adaptive correction of the entire multimode beam. 相似文献
39.
40.
Kinetics and Catalysis - A series of Cu-SSZ-13@CeO2 catalysts with surface modification with CeO2 was prepared by the modified self-resemble method based on the one-pot synthesized Cu-SSZ-13... 相似文献