全文获取类型
收费全文 | 12550篇 |
免费 | 1537篇 |
国内免费 | 1082篇 |
专业分类
化学 | 6518篇 |
晶体学 | 91篇 |
力学 | 517篇 |
综合类 | 47篇 |
数学 | 1029篇 |
物理学 | 3307篇 |
综合类 | 3660篇 |
出版年
2024年 | 60篇 |
2023年 | 215篇 |
2022年 | 369篇 |
2021年 | 407篇 |
2020年 | 387篇 |
2019年 | 352篇 |
2018年 | 335篇 |
2017年 | 305篇 |
2016年 | 433篇 |
2015年 | 489篇 |
2014年 | 622篇 |
2013年 | 801篇 |
2012年 | 956篇 |
2011年 | 917篇 |
2010年 | 670篇 |
2009年 | 656篇 |
2008年 | 732篇 |
2007年 | 646篇 |
2006年 | 600篇 |
2005年 | 517篇 |
2004年 | 463篇 |
2003年 | 378篇 |
2002年 | 417篇 |
2001年 | 349篇 |
2000年 | 253篇 |
1999年 | 363篇 |
1998年 | 290篇 |
1997年 | 302篇 |
1996年 | 298篇 |
1995年 | 234篇 |
1994年 | 228篇 |
1993年 | 187篇 |
1992年 | 133篇 |
1991年 | 129篇 |
1990年 | 129篇 |
1989年 | 102篇 |
1988年 | 98篇 |
1987年 | 47篇 |
1986年 | 46篇 |
1985年 | 31篇 |
1984年 | 24篇 |
1983年 | 20篇 |
1982年 | 13篇 |
1981年 | 13篇 |
1980年 | 17篇 |
1979年 | 10篇 |
1978年 | 22篇 |
1977年 | 10篇 |
1976年 | 13篇 |
1974年 | 12篇 |
排序方式: 共有10000条查询结果,搜索用时 14 毫秒
981.
982.
983.
Jie Zhao Ru Mo Li-Mei Tian Ling-Jie Song Shi-Fang Luan Jing-Hua Yin Lu-Quan Ren 《高分子科学》2018,36(4):472-478
High sensitive immunoassay platforms have gained intense attention due to their vital roles in early-stage disease diagnosis and therapeutic information feedback.Although random covalent-binding of antibody has been widely adopted in immunoassays due to its simplicity and effectiveness,it readily loses its activity and fails to exhibit high antigen-binding capacity.In this work,copolymer of zwitterionic sulfobetaine methacrylate (SBMA) and glycidyl methacrylate (GMA) brushes were immobilized onto inert polypropylene (PP) via surface-initiated atom transfer radical polymerization (ATRP) based on biomimetic dopamine pretreatment.Subsequently,boronic acid (BA) groups were covalently bonded via active GMA units,followed by the introduction of oriented immobilization of antibody.Owing to the oriented immobilization of antibody facilitated by BA groups in polymer brush,the bioactivity of antibody is well preserved,which endows the surface with significantly enhanced antigen-binding capacity.Moreover,the existence of SBMA segments in polymer brushes renders the surface high resistance to nonspecific protein adsorption,significantly alleviating the signal interference of antigen recognition.This strategy could find potential applications in developing high sensitive immunoassay platforms based on the different substrates. 相似文献
984.
Bioactive glass-chitosan-alginate hybrid scaffolds were fabricated using BG sol as a dual function additive, which behaves as both bioactive inorganic phase to confer the bioactivity and cross-linker to improve the structural stability and mechanical properties. 相似文献
985.
A homopolymer based on double B ← N bridged bipyridine was reported as a novel polymer electron acceptor. The resulting all-polymer solar cells show power conversion efficiencies of 2.44%–3.04%. 相似文献
986.
Photon affinity can serve as a probe for predicting the structures of protonated homodimers of amino acids. 相似文献
987.
Four Zn(II) complexes, [Zn L 2(SO4)]n ( 1 ), [Zn L 4(H2O)2]?2(NO3)?4EtOH ( 2 ), [Zn L 2Cl2]? L ( 3 ), and [Zn L 2Br2]? L ( 4 ) ( L = uniconazole), were synthesized using a hydrothermal method and characterized by elemental analysis, FT‐IR spectroscopy, and single‐crystal XRD. Complex 1 formed a one‐dimensional polymer chain. However, complexes 2 ‐ 4 were obtained as zero‐dimensional mononuclear coordination compounds. The antifungal activities of these complexes were then evaluated against four selected fungi using the mycelial growth rate method. The resulting data indicate that all complexes show better antifungal activities than their ligands and mixtures. In addition, the interactions between the metal salts of complexes 1 ‐ 4 and uniconazole seem to be synergistic. Furthermore, the polymer chain structure of complex 1 significantly enhanced the bioactivity, especially against Botryosphaeria ribis ( I ). Density functional theory (DFT) calculations were carried out to help explain the enhanced bioactivity after the formation of Zn(II) complexes. The resulting data show that the HOMO–LUMO energy gaps of complexes 1 ‐ 4 (0.0578, 0.0946, 0.1053, and 0.1245 eV) are smaller than that of the free ligand (0.1247 eV) and correlate with the antifungal activity of the zinc complexes. 相似文献
988.
Guo‐yu Ren Jie Li Xu‐zhan Wei Jin‐hua Zhou Biao Yan Zhao‐qi Guo Ying‐hui Ren Xiao‐hong Sun Hai‐xia Ma 《应用有机金属化学》2018,32(9)
In order to screen effective fungicides, three Zn (II) complexes, [Zn L 1 4 (NO3)2]·2H2O·2EtOH ( 1 ), [Zn L 2 4 (NO3)2] ( 2 ), and [Zn L 3 4 (DMF)2](NO3)2 ( 3 ), ( L 1 = paclobutrazol, L 2 = diniconazole, and L 3 = hexaconazole), were synthesized and characterized by elemental analysis, FT‐IR spectroscopy, and single‐crystal XRD. The antifungal activities of these complexes were then evaluated against four selected fungi using the mycelial growth rate method. The resulting data indicate that all the complexes show the enhanced antifungal activities than the corresponding ligand and mixtures. And, the interactions between the metal salt and ligands in the three complexes seem to be synergistic. According to the study of the influence of the structures on the activity, complex 2 with C=C linkage and 2,4‐dichlorophenyl moieties enhances the bioactivity significantly, especially against Wheat gibberellic ( II ). Density functional theory (DFT) calculations were carried out to help explain the enhanced bioactivity of the Zn (II) complexes. Meanwhile, all complexes are excellent grow‐regulators, especially complex 3 . The resulting data show that the complexes based on triazole fungicides have the potential applications in agriculture. 相似文献
989.
990.
A corona discharge (CD) ion mobility spectrometer combined with solid-phase microextraction was constructed. The detection limit and stability of the system for malathion detection were improved using a novel sample introduction port through which the sample desorption was performed in high-temperature drift tube and the sample was introduced directly to the ionization area. The working parameters of the distance between CD needle tip and carrier gas outlet, the drift tube and carrier gas temperature, the carrier gas flow, and the voltage on CD needle were selected. When the extraction time for standard malathion was set to 5?min, the detection limit was 0.96?µg?L?1 based on thrice the baseline noise, the linear range was 50–500?µg?L?1, the correlation coefficient was approximately 0.9941, and the relative standard deviation was below 10%. Malathion-spiked lake water samples were analyzed using the developed system and the recovery was 92–102%. This method is suitable for the rapid detection of organophosphorus pesticide residues. 相似文献