全文获取类型
收费全文 | 21657篇 |
免费 | 3945篇 |
国内免费 | 3117篇 |
专业分类
化学 | 16188篇 |
晶体学 | 226篇 |
力学 | 1329篇 |
综合类 | 184篇 |
数学 | 2335篇 |
物理学 | 8457篇 |
出版年
2024年 | 23篇 |
2023年 | 479篇 |
2022年 | 470篇 |
2021年 | 734篇 |
2020年 | 915篇 |
2019年 | 924篇 |
2018年 | 780篇 |
2017年 | 734篇 |
2016年 | 1074篇 |
2015年 | 1065篇 |
2014年 | 1245篇 |
2013年 | 1628篇 |
2012年 | 1982篇 |
2011年 | 1964篇 |
2010年 | 1403篇 |
2009年 | 1296篇 |
2008年 | 1444篇 |
2007年 | 1318篇 |
2006年 | 1219篇 |
2005年 | 1102篇 |
2004年 | 783篇 |
2003年 | 659篇 |
2002年 | 699篇 |
2001年 | 569篇 |
2000年 | 485篇 |
1999年 | 523篇 |
1998年 | 441篇 |
1997年 | 405篇 |
1996年 | 349篇 |
1995年 | 324篇 |
1994年 | 278篇 |
1993年 | 244篇 |
1992年 | 200篇 |
1991年 | 186篇 |
1990年 | 181篇 |
1989年 | 130篇 |
1988年 | 92篇 |
1987年 | 63篇 |
1986年 | 66篇 |
1985年 | 71篇 |
1984年 | 36篇 |
1983年 | 39篇 |
1982年 | 35篇 |
1981年 | 23篇 |
1980年 | 12篇 |
1977年 | 3篇 |
1957年 | 3篇 |
1942年 | 2篇 |
1930年 | 2篇 |
1916年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 91 毫秒
101.
Weiquan Xu Jin-Yu Chao Dr. Bohan Tang Prof. Zhan-Ting Li Prof. Jiang-Fei Xu Prof. Xi Zhang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(63):e202202200
A supramolecular organic framework-type photocatalyst, named TM-SOF, is constructed by the self-assembly of cucurbit[8]uril and a tetra-arm monomer containing four N, N’-dimethyl 2,5-bis(4-pyridinium)thiazolo[5,4-d]thiazole (MPT) moieties. Benefiting from the multivalent assembly, a photocatalytically active supramolecular MPT dimer can be stably formed in TM-SOF. In addition, TM-SOF exhibits better stability against temperature, substrate, and light irradiation. As a result, TM-SOF shows a significantly improved performance for the photocatalytic aerobic oxidation of aryl boronic acids and thioethers. It is anticipated that this line of research will provide a facile approach for fabricating high-performance supramolecular photocatalysis systems. 相似文献
102.
Jing He Mohan Yu Maofu Pang Yanqing Fan Zhe Lian Dr. Ying Wang Prof. Wenguang Wang Prof. Yajun Liu Prof. Hua Jiang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(13):e202103832
Structural designs combining cycloparaphenylenes (CPPs) backbone with planar chiral [2.2]paracyclophane ([2.2]PCP) lead to optical-active chiral macrocycles with intriguing properties. X-ray crystal analysis revealed aesthetic necklace-shaped structures and size-dependent packages with long-range channels. The macrocycles exhibit unique photophysical properties with high fluorescence quantum yield of up to 82 %, and the fluorescent color varies with ring size. In addition, size-dependent chiroptical properties with moderately large CPL dissymmetry factor of 10−3 and CPL brightness in the range of 30–40 M−1 cm−1 were observed. 相似文献
103.
Changmao Wang Yaqin Wang Haitang Xie Cuijiao Zhan Xuejun He Ran Liu Rongfeng Hu Jie Shen Yuanwei Jia 《Biomedical chromatography : BMC》2022,36(3):e5287
In this work, we developed and validated a highly sensitive, rapid and stable LC–MS/MS method for the determination of ibuprofen in human plasma with ibuprofen-d3 as a stable isotopically labeled internal standard (SIL-IS). Human plasma samples were prepared by one-step protein precipitation. The chromatographic separation was achieved on a Poroshell 120 EC-C18 (2.1 × 50 mm, 2.7 μm). Aqueous solution (containing 0.05% acetic acid and 5 mm NH4Ac) and methanol were selected as the mobile phase with gradient elution. An electrospray ionization source was applied and operated in negative ion mode. Multiple reaction monitoring mode was used for quantification using target fragment ions m/z 205.0 → 161.1 for ibuprofen and m/z 208.0 → 164.0 for SIL-IS, respectively. This method exhibited a linear range of 0.05–36 μg/ml for ibuprofen with correlation coefficient >0.99. Mean recoveries of ibuprofen in human plasma ranged from 78.4 to 80.9%. The RSD of intra- and inter-day precision were both < 5%. The accuracy was between 88.2 and 103.67%. The matrix effect was negligible in human plasma, including lipidemia and hemolytic plasma. A simple, efficient and accurate LC–MS/MS method was successfully established and applied to a pharmacokinetic study in healthy Chinese volunteers after a single oral administration of ibuprofen granules. 相似文献
104.
105.
何炳生 《高等学校计算数学学报》2020,(1):22-47
我们对文章的结构做这样的安排:第二节给出本文需要的预备知识;第三节简述单个目标函数问题(1.1)的己有算法和求解可能遇到的困难,第四节给出解决问题的预测-校正方法;第五节和第六节对问题(1.2)分别陈述己有方法的固有困难和我们提出的解决方案.最后,在第七节中,我们为提出的方法给出统一的算法框架,证明这类算法的收敛性和遍历意义下的收敛速率,同时给出我们的一些结论. 相似文献
106.
107.
在实验室实现聚变反应释放的能量大于点燃聚变反应所需能量的阈值是当今世界ICF研究的主要目标,实现这一目标仍需要深入研究一系列的关键物理问题。在ICF研究中,制靶能力的发展与提升至关重要,靶的质量是实验成功的核心要素之一。本文介绍了国际ICF靶制备工作近年来在新型烧蚀层材料靶丸、新型靶丸支撑技术、优化黑腔材料与构型以及减小燃料填充管直径等方面取得的一系列进展,并结合ICF物理需求,简要阐述了ICF靶的发展趋势。 相似文献
108.
通过分析光子诱发52,50Cr核反应的各类实验数据,澄清52Cr光子吸收截面评价数据与中子、质子出射截面测量值间的分歧,给出了52Cr中子出射截面实验数据的修正;选取EGLO模型光子强度函数,结合准氘模型,给出光子吸收截面。在此基础上,采用最新研制的光子与中重核反应计算程序MEND-G,通过优化理论模型参数,包括剩余核的能级密度和对能修正参数,给出光子能量在200 MeV范围内的n、p、${{\rm{\alpha }}}$ 等粒子出射核反应的截面,52,50Cr的计算结果在30 MeV以下能区很好地符合了现有实验数据,并按国际标准ENDF/B-6库格式给出了50,52,53,54Cr的全套数据文档,便于核工程用户使用。 相似文献
109.
110.
Long Lin Jingtao Huang Weiyang Yu Chaozheng He Hualong Tao Yonghao Xu Linghao Zhu Pengtao Wang Zhanying Zhang 《理论物理通讯》2020,72(3):35501-82
Gas molecules(such as CH4,CO,H2O,H2S,NH_3)adsorption on the pure and Au-doped WO3(001)surface have been studied by Density functional theory calculations with generalized gradient approximation.Based on the the calculation of adsorption energy,we found the most stable adsorption site for gas molecules by comparing the adsorption energies of different gas molecules on the WO3(001)surface.We have also compared the adsorption energy of five different gas molecules on the WO3(001)surface,our calculation results show that when the five kinds of gases are adsorbed on the pure WO3(001)surface,the order of the surface adsorption energy is CO>H2S>CH4>H2O>NH3.And the results show that NH3 is the most easily adsorbed gas among the other four gases adsorbed on the surface of pure WO3(001)surface.We also calculated the five different gases on the Au-doped WO3(001)surface.The order of adsorption energy was found to be different from the previous calculation:CO>CH4>H2S>H2O>NH3.These results provide a new route for the potential applications of Au-doped WO3 in gas molecules adsorption. 相似文献