全文获取类型
收费全文 | 1162篇 |
免费 | 138篇 |
国内免费 | 121篇 |
专业分类
化学 | 932篇 |
晶体学 | 40篇 |
力学 | 48篇 |
综合类 | 4篇 |
数学 | 145篇 |
物理学 | 252篇 |
出版年
2023年 | 12篇 |
2022年 | 11篇 |
2021年 | 28篇 |
2020年 | 17篇 |
2019年 | 31篇 |
2018年 | 21篇 |
2017年 | 25篇 |
2016年 | 50篇 |
2015年 | 56篇 |
2014年 | 62篇 |
2013年 | 86篇 |
2012年 | 81篇 |
2011年 | 92篇 |
2010年 | 48篇 |
2009年 | 40篇 |
2008年 | 76篇 |
2007年 | 58篇 |
2006年 | 60篇 |
2005年 | 49篇 |
2004年 | 56篇 |
2003年 | 44篇 |
2002年 | 61篇 |
2001年 | 47篇 |
2000年 | 30篇 |
1999年 | 28篇 |
1998年 | 22篇 |
1997年 | 12篇 |
1996年 | 13篇 |
1995年 | 11篇 |
1994年 | 17篇 |
1993年 | 16篇 |
1992年 | 12篇 |
1991年 | 8篇 |
1990年 | 13篇 |
1989年 | 7篇 |
1988年 | 4篇 |
1987年 | 7篇 |
1986年 | 5篇 |
1985年 | 8篇 |
1984年 | 10篇 |
1982年 | 15篇 |
1981年 | 9篇 |
1979年 | 8篇 |
1978年 | 4篇 |
1976年 | 4篇 |
1974年 | 7篇 |
1971年 | 6篇 |
1970年 | 4篇 |
1968年 | 4篇 |
1967年 | 4篇 |
排序方式: 共有1421条查询结果,搜索用时 131 毫秒
71.
Jong Young Joung Ha Yeon Lee Jongil Park Jee-Young Lee Byung Ha Chang Kyoung Tai No Ky-Youb Nam Jae Sung Hwang 《Applied biochemistry and biotechnology》2014,172(4):1882-1897
Melanocytes are unique cells that produce specific melanin-containing intracellular organelles called melanosomes. Melanosomes are transported from the perinuclear area of melanocytes toward the plasma membrane as they become more melanized in order to increase skin pigmentation. In this vesicular trafficking of melanosomes, Rab27a, melanophilin, and myosin Va play crucial roles in linking melanosomes to actin-based motors. To identify novel compounds to inhibit binding interface between Rab27a and melanophilin, a pharmacophore model was built based on a modeled 3D structure of the protein complex that describes the essential binding residues in the intermolecular interaction. A pharmacophore model was employed to screen a chemical library database. Finally, 25 virtual hits were selected for biological evaluations. The biological activities of 11 analogues were evaluated in a second assay. Two compounds were identified as having concentration-dependent inhibitory activity. By analyzing structure–activity relationships of derivatives of BMD-20, two hydroxyl functional groups were found to be critical for blocking the intermolecular binding between Rab27a and melanophilin. 相似文献
72.
Chin-Kuen Tai Pao-Ling Yeh Chun-Chi Chang Wen-Hao Chen Rong-Hou Wu Yu-Ma Chou Bo-Cheng Wang 《Research on Chemical Intermediates》2014,40(6):2355-2362
Recently, the organic synthesis and electronic device applications of π-conjugated polymer-based materials with low energy band gap (below 2 eV) and high values of incident photon to current efficiency have been presented. In the present study, the physical properties of polythiophene (PTH) and its derivative systems (PTs) were investigated as π-conjugated low energy band gap polymers. Density functional theory with periodic boundary condition (PBC), the B3LYP functional, and the 6-31G(d) basis set was applied to determine their geometric and electronic structures and corresponding energies (E HOMO, E LUMO, and E g = E LUMO ? E HOMO) from the monomer of thiophene and its derivatives for one-dimensional (1D) extension to polymer. The effects of 3-substitution in PTs including electron-donating (CH3–, C6H13–, OH–, Cl–, OCH3–, and CHO–) and electron-withdrawing groups (Cl–, CHO–, CN–, NO2–, CF3–, and COOH–) compared with PTH were investigated. According to the calculation results, PTs with electron-donating and electron-withdrawing substituents should exhibit red- and blue-shifts, respectively, compared with PTH. These calculation results show good agreement with experimental data and provide further information for molecular design considerations. 相似文献
73.
A new tripodal ligand, N,N′,N″-tri(salicylaldehyde)triaminotriethylamine (1) has been synthesized and characterized by elemental analysis, IR and UV spectroscopy, MS, and X-ray crystallography. X-ray diffraction analysis reveals that the three chains of the ligand form a cup-like structure. The ligand’s magnesium(II) complex has been synthesized and characterized by elemental analysis, conductivity, and IR and UV spectroscopy. The luminescence properties of the ligand and its magnesium(II) complex were investigated in DMF, CH3OH, and CH3CH2OH solution and in the solid state at room temperature. 相似文献
74.
Sahar Pakbaten Toopkanloo Tai Boon Tan Faridah Abas Mohammad Azam Imededdine Arbi Nehdi Chin Ping Tan 《Molecules (Basel, Switzerland)》2020,25(24)
In order to improve the membrane lipophilicity and the affinity towards the environment of lipid bilayers, squalene (SQ) could be conjugated to phospholipids in the formation of liposomes. The effect of membrane composition and concentrations on the degradation of liposomes prepared via the extrusion method was investigated. Liposomes were prepared using a mixture of SQ, cholesterol (CH) and Tween80 (TW80). Based on the optimal conditions, liposome batches were prepared in the absence and presence of SQ. Their physicochemical and stability behavior were evaluated as a function of liposome constituent. From the optimization study, the liposomal formulation containing 5% (w/w) mixed soy lecithin (ML), 0.5% (w/w) SQ, 0.3% (w/w) CH and 0.75% (w/w) TW80 had optimal physicochemical properties and displayed a unilamellar structure. Liposome prepared using the optimal formulation had a low particle size (158.31 ± 2.96 nm) and acceptable %increase in the particle size (15.09% ± 3.76%) and %trolox equivalent antioxidant capacity (%TEAC) loss (35.69% ± 0.72%) against UV light treatment (280–320 nm) for 6 h. The interesting outcome of this research was the association of naturally occurring substance SQ for size reduction without the extra input of energy or mechanical procedures, and improvement of vesicle stability and antioxidant activity of ML-based liposome. This study also demonstrated that the presence of SQ in the membrane might increase the acyl chain dynamics and decrease the viscosity of the dispersion, thereby limiting long-term stability of the liposome. 相似文献
75.
Katsuhiko Ariga Xiaofang Jia Jingwen Song Jonathan P. Hill David Tai Leong Yi Jia Junbai Li 《Angewandte Chemie (International ed. in English)》2020,59(36):15424-15446
Incorporation of non‐equilibrium actions in the sequence of self‐assembly processes would be an effective means to establish bio‐like high functionality hierarchical assemblies. As a novel methodology beyond self‐assembly, nanoarchitectonics, which has as its aim the fabrication of functional materials systems from nanoscopic units through the methodological fusion of nanotechnology with other scientific disciplines including organic synthesis, supramolecular chemistry, microfabrication, and bio‐process, has been applied to this strategy. The application of non‐equilibrium factors to conventional self‐assembly processes is discussed on the basis of examples of directed assembly, Langmuir–Blodgett assembly, and layer‐by‐layer assembly. In particular, examples of the fabrication of hierarchical functional structures using bio‐active components such as proteins or by the combination of bio‐components and two‐dimensional nanomaterials, are described. Methodologies described in this review article highlight possible approaches using the nanoarchitectonics concept beyond self‐assembly for creation of bio‐like higher functionalities and hierarchical structural organization. 相似文献
76.
77.
Reagen Ying‐Tai Su Li‐Ko Chiu Shan‐Wei Weng Ying‐Shiun Chou Raymond Chien‐Chao Tsiang 《Journal of Polymer Science.Polymer Physics》2012,50(4):280-288
White polymeric light‐emitting diode (WPLED) based on a single polymer, poly(3‐hexylthiophene‐alt‐9,9‐dioctylfluorene) (PTAF), has been successfully demonstrated. This conjugated alternating copolymer, PTAF, comprises 50 mol % of 3‐hexylthiophene which is an orange‐red color chromophore and 50 mol % 9,9‐dioctylfluorene which is a bluish‐green color chromophore. It was synthesized by Suzuki cross‐coupling reaction and has a molecular weight of 15,021 and polydispersity of 1.36. Nanocomposite consisting PTAF and graphene nanosheets enhances the optoelectronic properties and the device fabricated with a configuration of ITO/PEDOT:PSS/(PTAF + 1% graphene)/Ca/Al shows two‐color white electroluminescence with CIE 1931 coordinates of (0.28, 0.34). The white luminescence from a single polymer affords the WPLED device a simple structure and low fabrication cost. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011 相似文献
78.
79.
80.