全文获取类型
收费全文 | 1721篇 |
免费 | 126篇 |
国内免费 | 149篇 |
专业分类
化学 | 1499篇 |
晶体学 | 17篇 |
力学 | 48篇 |
综合类 | 11篇 |
数学 | 106篇 |
物理学 | 315篇 |
出版年
2024年 | 5篇 |
2023年 | 35篇 |
2022年 | 99篇 |
2021年 | 88篇 |
2020年 | 105篇 |
2019年 | 83篇 |
2018年 | 82篇 |
2017年 | 48篇 |
2016年 | 113篇 |
2015年 | 116篇 |
2014年 | 118篇 |
2013年 | 128篇 |
2012年 | 138篇 |
2011年 | 161篇 |
2010年 | 105篇 |
2009年 | 103篇 |
2008年 | 100篇 |
2007年 | 82篇 |
2006年 | 77篇 |
2005年 | 68篇 |
2004年 | 46篇 |
2003年 | 40篇 |
2002年 | 5篇 |
2001年 | 9篇 |
2000年 | 5篇 |
1999年 | 8篇 |
1998年 | 7篇 |
1997年 | 2篇 |
1996年 | 4篇 |
1995年 | 1篇 |
1994年 | 7篇 |
1992年 | 3篇 |
1991年 | 1篇 |
1990年 | 2篇 |
1986年 | 1篇 |
1959年 | 1篇 |
排序方式: 共有1996条查询结果,搜索用时 15 毫秒
41.
Xiuyan Wan Hui Zhong Wei Pan Yanhua Li Yuanyuan Chen Na Li Bo Tang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(40):14272-14277
Dihydroartemisinin (DHA) has attracted increasing attention as an anticancer agent. However, using DHA to treat cancer usually depends on the synergistic effects of exogenous components, and the loss of DHA during delivery reduces its effectiveness in cancer therapy. Reported herein is a programmed release nanoplatform of DHA to synergistically treat cancer with a Fe‐TCPP [(4,4,4,4‐(porphine‐5,10,15,20‐tetrayl) tetrakis(benzoic acid)] NMOF (nanoscale MOF) having a CaCO3 mineralized coating, which prevents DHA leakage during transport in the bloodstream. When the nanoplatform arrives at the tumor site, the weakly acidic microenvironment and high concentration of glutathione (GSH) trigger DHA release and TCPP activation, enabling the synergistic Fe2+‐DHA‐mediated chemodynamic therapy, Ca2+‐DHA‐mediated oncosis therapy, and TCPP‐mediated photodynamic therapy. In vivo experiments demonstrated that the nanoplatform showed enhanced anticancer efficiency and negligible toxicity. 相似文献
42.
Yuanyuan Ping Yuxiu Li Jieping Zhu Wangqing Kong 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(6):1576-1587
The enantioselective synthesis of molecules containing quaternary stereocenters is a field of intense research interest and development. Among the known organic transformations, carbopalladation‐initiated domino transformations constitutes a general method for the construction of compounds containing cyclic or spiro quaternary stereocenters. In this Minireview, recent achievements in palladium‐catalyzed domino Heck/C?H functionalizations and developments in enantioselective carbopalladation‐initiated domino processes are summarized. 相似文献
43.
Yining Zhao Zhangyao Xu Tianming Wang Yuanyuan Li Li Yang Shaoyong Liu Rong Shi Yueming Ma 《Biomedical chromatography : BMC》2019,33(7)
Tanreqing capsule (TRQC) is a formulation frequently used in traditional Chinese medicine to treat pyrexia, cough, expectoration and pharyngalgia. Since the pharmacological action of traditional Chinese medicines is closely related to their complex and diverse constituents, understanding the exact composition of TRQC is important to elucidate its clinical effectiveness and mechanism of action as well as to establish quality control methods and resolve safety issues. Herein, we employed high‐performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry for the simultaneous quantitation of 23 bioactive compounds in five batches of TRQC; the analytes could be categorized into five types: organic acids (seven compounds), flavonoids (10 compounds), iridoids (two compounds), phenylethanoid glycosides (two compounds) and bile acids (two compounds). The calibration curves for all analytes showed good linearity (r > 0.9953), and the inter‐ and intra‐day precisions did not exceed 4.94 and 4.97%, respectively. The recoveries varied from 90.47% to 109.80%; the corresponding relative standard deviations (RSDs) did not exceed 4.94%; and the repeatability (RSD < 4.72%) and stability (RSD < 4.88%) were also within acceptable limits. Thus, this study can be viewed as a fundamental reference for setting comprehensive TRQC quality standards. 相似文献
44.
Yanni Lv Xianpeng Shi Jia Fu Qianqian Jia Yuanyuan Lin Hongying Wang Xin Yang Shengli Han 《Biomedical chromatography : BMC》2019,33(9)
Marsdenia tenacissima, or Tongguanteng in Chinese, is a traditional Chinese herb and has a broad application in clinical practice for its pharmacological effects of treating asthma, pneumonia, tonsillitis, pharyngitis tumors, etc. However, few studies have reported the screening of the active components of this medicine for tumor therapy. In this work, a two‐dimensional analytical system was developed to screen antagonists of epidermal growth factor receptor (EGFR) from M. tenacissima. A fraction was retained on the EGFR cell membrane chromatography (CMC) column, separated and identified as tenacissoside G (TG), tenacissoside H (TH) and tenacissoside I (TI) by two‐dimensional HPLC–IT–TOF–MS. Molecular docking and 3‐(4,5‐dimethyl‐2‐thiazolyl)‐2,5‐diphenyl‐2‐H‐tetrazolium bromide (MTT) assay were carried out to assess the activity of TS (including TG, TH and TI). Molecular docking results showed that the binding mode of TS on EGFR is similar to that of gefitinib. The MTT assay demonstrated that gefitinib and TS (especially TI) could inhibit the growth of EGFR highly expressed cell lines in a dose‐dependent manner in the range of 5–50 μmol/L. In conclusion, the two‐dimensional EGFR/CMC–HPLC–IT–TOF–MS system could be a useful approach in drug discovery from traditional Chinese medicines for searching for potential antitumor candidates. 相似文献
45.
Jialong Duan Yuanyuan Zhao Yudi Wang Xiya Yang Qunwei Tang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(45):16293-16297
The all‐inorganic CsPbBr3 perovskite solar cell (PSC) is a promising solution to balance the high efficiency and poor stability of state‐of‐the‐art organic–inorganic PSCs. Setting inorganic hole‐transporting layers at the perovskite/electrode interface decreases charge carrier recombination without sacrificing superiority in air. Now, M‐substituted, p‐type inorganic Cu(Cr,M)O2 (M=Ba2+, Ca2+, or Ni2+) nanocrystals with enhanced hole‐transporting characteristics by increasing interstitial oxygen effectively extract holes from perovskite. The all‐inorganic CsPbBr3 PSC with a device structure of FTO/c‐TiO2/m‐TiO2/CsPbBr3/Cu(Cr,M)O2/carbon achieves an efficiency up to 10.18 % and it increases to 10.79 % by doping Sm3+ ions into perovskite halide, which is much higher than 7.39 % for the hole‐free device. The unencapsulated Cu(Cr,Ba)O2‐based PSC presents a remarkable stability in air in either 80 % humidity over 60 days or 80 °C conditions over 40 days or light illumination for 7 days. 相似文献
46.
Yuanyuan Ma Tianxiang Chen Muhammad Zubair Iqbal Fang Yang Norbert Hampp Aiguo Wu Liqiang Luo 《Electrophoresis》2019,40(16-17):2011-2028
As a result of their advantages for superparamagnetic properties, good biocompatibility, and high binding capacity, functionalized magnetic materials became widely popular over the past couple of decades, being applied on large scale in various processes of sample preparation for biomedicine. In this work, we perform an in‐depth review on the current progress in the field of magnetic bead separation, discussing in detail the physical basis of this process, various synthesis methods and surface modification strategies. We place special focus of attention as well on the latest applications of magnetic polymer microspheres in cell separation, protein purification, immobilized enzyme, nucleic acid separation, and extraction of bioactive compounds with low molecular weight. Existing problems are highlighted and possible trends of magnetic separation techniques for biomedicine in the future are proposed. 相似文献
47.
48.
49.
Benan K?lba?Author VitaeMetin BalciAuthor Vitae 《Tetrahedron》2011,67(13):2355-2389
50.