全文获取类型
收费全文 | 21188篇 |
免费 | 3549篇 |
国内免费 | 2452篇 |
专业分类
化学 | 14637篇 |
晶体学 | 220篇 |
力学 | 1174篇 |
综合类 | 143篇 |
数学 | 3023篇 |
物理学 | 7992篇 |
出版年
2024年 | 19篇 |
2023年 | 449篇 |
2022年 | 428篇 |
2021年 | 642篇 |
2020年 | 904篇 |
2019年 | 820篇 |
2018年 | 736篇 |
2017年 | 699篇 |
2016年 | 1042篇 |
2015年 | 972篇 |
2014年 | 1149篇 |
2013年 | 1549篇 |
2012年 | 1827篇 |
2011年 | 1906篇 |
2010年 | 1344篇 |
2009年 | 1230篇 |
2008年 | 1379篇 |
2007年 | 1219篇 |
2006年 | 1074篇 |
2005年 | 974篇 |
2004年 | 770篇 |
2003年 | 680篇 |
2002年 | 722篇 |
2001年 | 567篇 |
2000年 | 440篇 |
1999年 | 436篇 |
1998年 | 346篇 |
1997年 | 320篇 |
1996年 | 344篇 |
1995年 | 325篇 |
1994年 | 255篇 |
1993年 | 192篇 |
1992年 | 205篇 |
1991年 | 183篇 |
1990年 | 147篇 |
1989年 | 124篇 |
1988年 | 72篇 |
1987年 | 78篇 |
1986年 | 94篇 |
1985年 | 77篇 |
1984年 | 62篇 |
1983年 | 51篇 |
1982年 | 29篇 |
1981年 | 23篇 |
1980年 | 18篇 |
1979年 | 20篇 |
1976年 | 18篇 |
1975年 | 15篇 |
1974年 | 18篇 |
1973年 | 25篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
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
2.
Megha Sen Chowdhury Dr. Selcuk Gumus Dr. Sanchari Dasgupta Dr. Ishani Majumder Dr. Abir Bhattacharya Dr. Debasis Das Dr. Jayanta Mukhopadhyay Dr. Debosreeta Bose Dr. Saumya Dasgupta Dr. Yuksel Akinay Dr. Madhumita Mukhopadhyay 《ChemistryOpen》2022,11(6):e202200033
We report, for the first time, a detailed crystallographic study of the supramolecular arrangement for a set of zinc(II) Schiff base complexes containing the ligand 2,6-bis((E)-((2-(dimethylamino)ethyl)imino)methyl)-4-R-phenol], where R=methyl/tert-butyl/chloro. The supramolecular study acts as a pre-screening tool for selecting the compartmental ligand R of the Schiff base for effective binding with a targeted protein, bovine serum albumin (BSA). The most stable hexagonal arrangement of the complex [Zn − Me] (R=Me) stabilises the ligand with the highest FMO energy gap (ΔE=4.22 eV) and lowest number of conformations during binding with BSA. In contrast, formation of unstable 3D columnar vertebra for [Zn − Cl] (R=Cl) tend to activate the system with lowest FMO gap (3.75 eV) with highest spontaneity factor in molecular docking. Molecular docking analyses reported in terms of 2D LigPlot+ identified site A, a cleft of domains IB, IIIA and IIIB, as the most probable protein binding site of BSA. Arg144, Glu424, Ser428, Ile455 and Lys114 form the most probable interactions irrespective of the type of compartmental ligands R of the Schiff base whereas Arg185, Glu519, His145, Ile522 act as the differentiating residues with ΔG=−7.3 kcal mol−1. 相似文献
3.
We investigate the possibility of phantom crossing in the dark energy sector and the solution for the Hubble tension between early and late universe observations. We use robust combinations of different cosmological observations, namely the Cosmic Microwave Background (CMB), local measurement of Hubble constant (), Baryon Acoustic Oscillation (BAO) and SnIa for this purpose. For a combination of CMB+BAO data that is related to early universe physics, phantom crossing in the dark energy sector was confirmed at a 95% confidence level and we obtained the constraint km/s/Mpc at a 68% confidence level, which is in perfect agreement with the local measurement by Riess et al. We show that constraints from different combinations of data are consistent with each other and all of them are consistent with phantom crossing in the dark energy sector. For the combination of all data considered, we obtained the constraint km/s/Mpc at a 68% confidence level and the phantom crossing happening at the scale factor at a 68% confidence level. 相似文献
4.
Yu He Yating Guo Yanbin Yu Peifu Luo Honglong Qiu Guoming Huang 《Particle & Particle Systems Characterization》2021,38(5):2100038
In this study, manganese tellurite (MnTeO3) nanoparticles are developed as theranostic agents for magnetic resonance imaging (MRI)-guided photothermal therapy of tumor. MnTeO3 nanoparticles are synthesized via a simple one-step method. The as-synthesized MnTeO3 nanoparticles with uniform size show good biocompatibility. In particular, MnTeO3 nanoparticles exhibit a high photothermal conversion efficiency (η = 26.3%), which is higher than that of gold nanorods. Moreover, MnTeO3 nanoparticles also have high MRI performance. The longitudinal relaxivity (r1) value of MnTeO3 nanoparticles is determined to be 8.08 ± 0.2 mm −1 s−1, which is higher than that of clinically approved T1-contrast agents Gd-DTPA (4.49 ± 0.1 mm −1 s−1). The subsequent MnTeO3 nanoparticles-mediated photothermal therapy displays a highly efficient ablation of tumor cells both in vitro and in vivo with negligible toxicity. It is demonstrated that MnTeO3 nanoparticles can serve as promising theranostic agents with great potentials for MRI-guided photothermal therapy. 相似文献
5.
Journal of Algebraic Combinatorics - APR tilts for path algebra kQ can be realized as the mutation of the quiver Q in $${\mathbb Z}Q$$ with respect to the translation. In this paper, we show that... 相似文献
6.
Bohuai Xiao Jianqiao Dong Zhiye Wang Xu Wang Mingjun Sun Jing Guo Gongming Qian Yunchuan Li Shuai Chang 《Chemphyschem》2022,23(7):e202100833
One important prerequisite for the fabrication of molecular functional device strongly relies on the understanding the conducting behaviors of the metal-molecule-metal junction that can respond to an external stimulus. The model Lewis basic molecule 4,4′-(pyridine-3,5-diyl)dibenzonitrile (DBP), which can react with Lewis acid and protic acid, was synthesized. Then, the molecular conducting behavior of DBP, DBP-B(C6F5)3, and DBP-TfOH (DBP-B(C6F5)3, and DBP-TfOH were produced by Lewis acid and protonic acid treatment of DBP) was researched and compared. Given that their identical physical paths for DBP, DBP-B(C6F5)3, and DBP-TfOH to sustain charge transport, our results indicate that modifying the molecular electronic structure, even not directly changing the conductive physical backbone, can tune the charge transporting ability by nearly one order of magnitude. Furthermore, the addition of another Lewis base triethylamine (of stronger alkaline than DBP), to Lewis acid-base pair reverts the electrical properties back to that of a single DBP junction, that is constructive to propose a useful but simple strategy for the design and construction of reversible and controllable molecular device based on pyridine derived molecule. 相似文献
7.
Yuan Xin Zhang Shuren Zhong Xuanmeng Yuan Hao Song Dongfan Wang Xiaoyu Yu Hanyang Guo Zijian 《中国科学:化学(英文版)》2022,65(10):1978-1984
Science China Chemistry - Oncogenic KRAS reprograms pancreatic ductal adenocarcinoma (PDAC) cells to a state that is awfully resistant to apoptosis. An alternative coping strategy is to trigger a... 相似文献
8.
Mathematical Notes - All the groups considered in this paper are finite, and $$G$$ always denotes a finite group; $$\sigma$$ is a partition of the set $$\mathbb{P}$$ of all primes, i.e.,... 相似文献
9.
Can Li Dr. Zheng Yang Lei Wang Prof. Dr. Yinlong Guo Prof. Dr. Zheng Huang Prof. Dr. Shengming Ma 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(15):6337-6342
An efficient pincer-ligand-based cobalt-complex-catalyzed allene hydroboration affording Z-allylic boronates is described. The reaction demonstrates an excellent regio- as well as Z-stereoselectivity and a wide substrate scope that tolerates many functional groups. Based on solvent-assisted electrospray ionization mass spectrometry (SAESI-MS) studies, a rationale for the cobalt-catalyzed hydroboration involving the highly selective insertion of an allene into the Co−H bond to form Z-allylic cobalt intermediates is proposed. 相似文献
10.
Wang Xinglei Guo Hangxu Wang Fan Tan Tianshe Wu Hang Zhang Hongxia 《Journal of Radioanalytical and Nuclear Chemistry》2020,324(3):1151-1165
Journal of Radioanalytical and Nuclear Chemistry - In this study, the halloysite nanotubes was characterized and the adsorption of Th(IV) and U(VI) on halloysite nanotubes was investigated as a... 相似文献