全文获取类型
收费全文 | 8539篇 |
免费 | 1324篇 |
国内免费 | 671篇 |
专业分类
化学 | 5740篇 |
晶体学 | 87篇 |
力学 | 504篇 |
综合类 | 36篇 |
数学 | 1002篇 |
物理学 | 3165篇 |
出版年
2024年 | 23篇 |
2023年 | 163篇 |
2022年 | 286篇 |
2021年 | 296篇 |
2020年 | 366篇 |
2019年 | 303篇 |
2018年 | 274篇 |
2017年 | 260篇 |
2016年 | 423篇 |
2015年 | 429篇 |
2014年 | 470篇 |
2013年 | 596篇 |
2012年 | 787篇 |
2011年 | 751篇 |
2010年 | 528篇 |
2009年 | 487篇 |
2008年 | 549篇 |
2007年 | 418篇 |
2006年 | 457篇 |
2005年 | 330篇 |
2004年 | 265篇 |
2003年 | 218篇 |
2002年 | 173篇 |
2001年 | 137篇 |
2000年 | 146篇 |
1999年 | 175篇 |
1998年 | 154篇 |
1997年 | 128篇 |
1996年 | 132篇 |
1995年 | 114篇 |
1994年 | 95篇 |
1993年 | 79篇 |
1992年 | 79篇 |
1991年 | 76篇 |
1990年 | 44篇 |
1989年 | 38篇 |
1988年 | 39篇 |
1987年 | 35篇 |
1986年 | 28篇 |
1985年 | 21篇 |
1984年 | 20篇 |
1983年 | 20篇 |
1982年 | 9篇 |
1981年 | 14篇 |
1980年 | 9篇 |
1977年 | 6篇 |
1976年 | 10篇 |
1975年 | 9篇 |
1973年 | 8篇 |
1972年 | 6篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
131.
Li-Jun Li Cheng Wang Yu Qiao Xiao-Yan Yang Xing-Xing Hua Jian-Long Du 《Research on Chemical Intermediates》2014,40(1):413-424
A series of platinum(II) complexes of reduced amino acid esters Schiff bases were synthesized as potential anticancer agents and characterized by 1H NMR, EA, IR, and molar conductivity. These compounds were tested for their DNA interaction with salmon sperm DNA by ultraviolet spectrum and CD spectrum, and their in vitro anticancer activities have been validated against HL-60, KB, BGC-823, and Bel-7402 cell lines by MTT assay. The cytotoxicity of complexes 5d and 5f are better than cisplatin against Bel-7402 cell lines, and show a close cytotoxic effect against HL-60 cell line. 相似文献
132.
133.
Geng Tianfeng Du Chunyu Cheng Xinqun Xu Xing Jian Jiyuan He Xiaoshu Zuo Pengjian Yin Geping 《Journal of Solid State Electrochemistry》2019,23(1):101-108
Journal of Solid State Electrochemistry - Li-rich layered oxide (LrLO) cathode has attracted much attention for Li-ion batteries in recent years due to its superior capacity of exceeding... 相似文献
134.
Tao Yong Cao Yanbing Hu Guorong Chen Pengwei Peng Zhongdong Du Ke Jia Ming Huang Yong Xia Jin Li Luyu Xie Xiaoming 《Journal of Solid State Electrochemistry》2019,23(7):2243-2250
Journal of Solid State Electrochemistry - LiFePO4 cathode material is considered as prospective materials for lithium-ion batteries and attracted great interest because of excellent cyclic... 相似文献
135.
Zhu B Yuan F Li R Li Y Wei Q Ma Z Du B Zhang X 《Chemical communications (Cambridge, England)》2011,47(25):7098-7100
A simple but highly selective colorimetric and ratiometric fluorescent chemodosimeter was designed and synthesized to detect fluoride ions (F(-)) in aqueous solution and living cells by virtue of the strong affinity of F(-) toward silicon. 相似文献
136.
Maintaining the predictive abilities of multivariate calibration models by spectral space transformation 总被引:1,自引:0,他引:1
Du W Chen ZP Zhong LJ Wang SX Yu RQ Nordon A Littlejohn D Holden M 《Analytica chimica acta》2011,690(1):64-70
In quantitative on-line/in-line monitoring of chemical and bio-chemical processes using spectroscopic instruments, multivariate calibration models are indispensable for the extraction of chemical information from complex spectroscopic measurements. The development of reliable multivariate calibration models is generally time-consuming and costly. Therefore, once a reliable multivariate calibration model is established, it is expected to be used for an extended period. However, any change in the instrumental response or variations in the measurement conditions can render a multivariate calibration model invalid. In this contribution, a new method, spectral space transformation (SST), has been developed to maintain the predictive abilities of multivariate calibration models when the spectrometer or measurement conditions are altered. SST tries to eliminate the spectral differences induced by the changes in instruments or measurement conditions through the transformation between two spectral spaces spanned by the corresponding spectra of a subset of standardization samples measured on two instruments or under two sets of experimental conditions. The performance of the method has been tested on two data sets comprising NIR and MIR spectra. The experimental results show that SST can achieve satisfactory analyte predictions from spectroscopic measurements subject to spectrometer/probe alteration, when only a few standardization samples are used. Compared with the existing popular methods designed for the same purpose, i.e. global PLS, univariate slope and bias correction (SBC) and piecewise direct standardization (PDS), SST has the advantages of implementation simplicity, wider applicability and better performance in terms of predictive accuracy. 相似文献
137.
The title cobalt(II) coordination polymer, [Co(Atibdc)(Dpa)] n (I) (H2Atibdc = 5-amino-2,4,6-triiodoisophthalic acid, Dpa = 2,2′-dipyridylanine), has been synthesized under solvothermal conditions and characterized by elemental analysis, IR, and X-ray crystallography structural analysis. Complex I exhibits a one-dimensional chain structure in which 5-amino-2,4,6-triiodoisophthalate as a bridging ligand interconnects adjacent two Co(II) centers to form a helical chain structure. The asymmetric unit includes one Co(II) center, one atibdc ligand, and one Dpa ligand. Each Co(II) center is five-coordinated and surrounded by two nitrogen atoms and three oxygen atoms from one Dpa ligand and two individual Atibdc ligands, leading to distorted trigonal bipyramid geometry. Adjacent chains are further linked through hydrogen bonds, C-H-π and π-π stacking interactions to form a three-dimensional supramolecular framework. 相似文献
138.
Da-Wei Wang Tao Wang Lin Du Jie Zhou Tong Yan Qi-Hua Zhao 《Structural chemistry》2018,29(4):1013-1023
Four new complexes [M(3-tba)2(H2O)4] (1–3) and [Co(4-tba)2(H2O)4] (4) {M = Zn (1), Ni (2), Co (3), 3-Htba = 3-(1H-1,2,4-triazol-1-yl)benzoic acid, 4-Htba = 4-(1H-1,2,4-triazol-1-yl)benzoic acid} have been synthesized under solvothermal conditions and structurally characterized by single crystal X-ray diffraction. Complexes 1–4 are also determined by elemental analysis, X-ray powder diffraction, IR and electronic spectroscopy. Single crystal X-ray diffraction reveals that complexes 1–3 are isostructural and they crystallize in the orthorhombic space group of Pbca, while complex 4 belongs to triclinic system with Pī space group. Based on different intermolecular hydrogen bonding and π···π stacking interactions, complexes 1–4 further assembled into 3D supramolecular frameworks. Hirshfeld surface analysis was used to further study the intermolecular interactions of the complexes. The thermogravimetric analyses (TGA) reveal that these complexes possess good thermal stability, and the differential scanning calorimetry (DSC) analyses show intense exothermic phenomena in the decomposition processes of triazole groups. Besides, the photoluminescence property of complex 1 in the solid state is also determined. 相似文献
139.
Substituent effects on the redox potentials of dihydroxybenzenes: theoretical and experimental study
Tao Liu Meng-Meng Liu Xiao-Wen Zheng Chong-Yang Du Xiang-Yang Cui Lu Wang Ling-Li Han Zhang-Yu Yu 《Tetrahedron》2014
The redox reactions of p-hydroquinone and pyrocatechol undergo a two-proton-two-electron process in aqueous solution. We calculated their redox potentials at the B3LYP/6-311+G(d,p) level, and verified the values by employing cyclic voltammetry experiments. Then we selected seven substituent groups (–F, –Cl, –OH, –COOH, –CN, –NH2, and –NO2 groups) to systematically investigate the substituent effect, including the sort, position, and number of the substituent, on the redox potentials of p-hydroquinone and pyrocatechol. The calculated results show that –NH2 and –OH groups can decrease the redox potentials, while –F, –Cl, –COOH, –CN, and –NO2 groups increase the potential values of p-hydroquinone and pyrocatechol. The calculations can accurately predict the substituent effects on the redox potentials of pyrocatechol and p-hydroquinone. We would expect that the accurate calculation results for the model systems could be applied in the prediction of electrode potentials of other molecules. 相似文献
140.
Baocai Du Renyong Geng Wenliang Tan Yuchao Mao Donghui Li Xue Zhang Dan Liu Weihua Tang Wenchao Huang Tao Wang 《Journal of Energy Chemistry》2021,(3):131-137
Molecular ordering within the photoactive layer plays a crucial role in determining the device performance of organic solar cells(OSCs).However,the simultaneous molecular ordering processes of polymer donors and non-fullerene acceptors(NFAs)during solution casting usually bring confinement effect,leading to insufficient structural order of photovoltaic components.Herein,the molecular packing of mINPOIC NFA is effectively formed through a heating induced aggregation strategy,with the aggregation of PBDB-T,which has a strong temperature dependence,is retarded by casting on a preheated substrate to reduce its interference toward m-INPOIC.A sequent thermal annealing treatment is then applied to promote the ordering of PBDB-T and achieve balanced aggregation of both donors and acceptors,resulting in the achievement of a maximum efficiency of 13.9% of PBDB-T:m-INPOIC binary OSCs.This work disentangles the interactions of donor polymer and NFA during the solution casting process and develops a rational strategy to enhance the molecular packing of NFAs to boost device performance. 相似文献