全文获取类型
收费全文 | 29938篇 |
免费 | 4211篇 |
国内免费 | 2712篇 |
专业分类
化学 | 20462篇 |
晶体学 | 284篇 |
力学 | 1944篇 |
综合类 | 273篇 |
数学 | 3279篇 |
物理学 | 10619篇 |
出版年
2024年 | 105篇 |
2023年 | 589篇 |
2022年 | 907篇 |
2021年 | 972篇 |
2020年 | 1112篇 |
2019年 | 1081篇 |
2018年 | 911篇 |
2017年 | 813篇 |
2016年 | 1279篇 |
2015年 | 1268篇 |
2014年 | 1536篇 |
2013年 | 2049篇 |
2012年 | 2629篇 |
2011年 | 2657篇 |
2010年 | 1646篇 |
2009年 | 1632篇 |
2008年 | 1736篇 |
2007年 | 1659篇 |
2006年 | 1489篇 |
2005年 | 1227篇 |
2004年 | 940篇 |
2003年 | 789篇 |
2002年 | 751篇 |
2001年 | 561篇 |
2000年 | 558篇 |
1999年 | 651篇 |
1998年 | 578篇 |
1997年 | 574篇 |
1996年 | 659篇 |
1995年 | 506篇 |
1994年 | 464篇 |
1993年 | 388篇 |
1992年 | 371篇 |
1991年 | 322篇 |
1990年 | 255篇 |
1989年 | 202篇 |
1988年 | 157篇 |
1987年 | 136篇 |
1986年 | 127篇 |
1985年 | 118篇 |
1984年 | 88篇 |
1983年 | 61篇 |
1982年 | 41篇 |
1981年 | 36篇 |
1980年 | 18篇 |
1978年 | 19篇 |
1977年 | 23篇 |
1976年 | 20篇 |
1975年 | 28篇 |
1974年 | 27篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
891.
Pengfei Zhao Miaoduo Deng Peiting Huang Jia Yu Xingjie Guo Longshan Zhao 《Analytical and bioanalytical chemistry》2016,408(23):6381-6392
892.
893.
Structure‐guided RP‐HPLC chromatography of diastereomeric α‐helical peptide analogs substituted with single amino acid stereoisomers 下载免费PDF全文
YiBing Huang Ling Pan LianJing Zhao Colin T. Mant Robert S. Hodges Yuxin Chen 《Biomedical chromatography : BMC》2014,28(4):511-517
An α‐helical model peptide (Ac‐EAEKAAKE‐X‐EKAAKEAEK‐amide) was used as a template to examine the efficacy of conventional reversed‐phase high‐performance liquid chromatography (RP‐HPLC) in separating peptide analogs with single substitutions (at position X) of diasteromeric amino acids Ile, allo‐Ile, d ‐Ile and d ‐allo‐Ile. We compared differences in peptide retention behavior on a C8 column and a C18 column at different temperatures. We demonstrated how subtle differences in peptide secondary structure affected by the different substitutions of amino acids with identical overall hydrophobicity enabled effective resolution of these peptide analogs. We also demonstrated the ability of RP‐HPLC to separate Ile‐ and allo‐Ile‐substituted analogs of a 26‐residue α‐helical antimicrobial peptide (AMP), with the substitution site towards the C‐terminus of the α‐helix. These peptides show different values of antibacterial activity and hemolytic activity, and different selectivity against bacteria and human cells. Our results underline the ability of RP‐HPLC to resolve even difficult diasteromeric peptide mixtures as well as its value in monitoring very subtle hydrophobicity changes in de novo‐designed AMP. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
894.
895.
896.
Dual‐responsive supramolecular self‐assembly of inclusion complex of an azobenzene‐ended poly(ε‐caprolactone) with a water‐soluble pillar[6]arene and its application in controlled drug release 下载免费PDF全文
Zaizai Tong Junyi Zhou Runsheng Huang Jie Zhou Runke Zhang Wangqian Zhuo Guohua Jiang 《Journal of polymer science. Part A, Polymer chemistry》2017,55(15):2477-2482
Dual photo‐ and pH‐responsive polymeric vesicles are constructed from a host–guest complex between a water‐soluble pillar[6]arene and an azobenzene ended functionalized poly(ε‐caprolactone). Reversible morphological transitions between vesicles and solid aggregates are achieved upon repeated UV stimulus and pH stimulus. Moreover, the polymeric vesicles present excellent cytocompatibility toward HepG2 cells and can be further applied for controlled release of a hydrophilic model drug, DOX?HCl. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55 , 2477–2482 相似文献
897.
898.
Rong‐Ho Lee Jian‐Lun Huang Chun‐Han Chi 《Journal of Polymer Science.Polymer Physics》2013,51(2):137-148
In this study, the maleimide‐thiophene copolymer‐functionalized graphite oxide sheets (PTM21‐GOS) and carbon nanotubes (PTM21‐CNT) were developed for polymer solar cell (PSC) applications. The grafting of PTM21‐OH onto the CNT and GO sheets was confirmed using FTIR spectroscopy. PTM21‐CNT and PTM21‐GOS exhibited excellent dispersal behavior in organic solvents. Better thermal stability was observed for PTM21‐CNT and PTM21‐GOS as compared with that for PTM21‐OH. In addition, the optical band gaps of PTM21‐GOS and PTM21‐CNT were lower than that of PTM21‐OH. We incorporated PTM21‐GOS and PTM21‐CNT individually into poly(3‐hexylthiophene) (P3HT)/[6,6]‐phenyl‐C61‐butyric acid methyl ester (PCBM) blends for use as photoconversion layers of PSCs. Good distributional homogeneity was observed for PTM21‐GOS or PTM21‐CNT in the P3HT/PCBM blend film. The UV–vis absorption peaks of the blend films red‐shifted slightly upon increasing the content of PTM21‐GOS or PTM21‐CNT. The band gap energies and LUMO/HOMO energy levels of the P3HT/PTM21‐GOS and P3HT/PTM21‐CNT blend films were slightly lower than those of the P3HT film. The conjugated polymer‐functionalized PTM21‐GOS and PTM21‐CNT behaved as efficient electron acceptors and as charge‐transport assisters when incorporated into the photoactive layers of the PSCs. PV performance of the PSCs was enhanced after incorporating PTM21‐GOS or PTM21‐CNT in the P3HT/PCBM blend. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2013 相似文献
899.
Wenjin Zheng Chen Huang Changhe Zhang Yi-Feng Zhou Ji-Dong Lou 《Research on Chemical Intermediates》2013,39(2):499-504
A simple, rapid, and efficient oxidation of oximes to the corresponding ketones and aldehydes with manganese dioxide catalyzed by kieselguhr under solvent-free conditions at room temperature in the yields between 82 and 98 is described. It seems that kieselguhr in the present procedure can highly expedite the reaction rate. By comparing to other methods described previously, the main advantages of this oxidation are that the oxidations are more efficient, the reaction conditions are milder, the reaction times are shorter, and the work-up is easier. Furthermore, the amount of manganese dioxide used in this oxidation is largely decreased. 相似文献
900.
Huiyun Wu Xin Li Shen Sheng Zhisong Huang Shuhai Huang Siqing Zhao Hua Wang Zhenhai Sun Xiegu Xu Rui Xiao 《Optik》2013
Model of an optical system with coherent laser array source and the piston phase optimized by the stochastic parallel gradient descent algorithm is established. With this model, theory of beam propagation through the optical system in turbulent atmosphere is analyzed, and the analytical formulas of the beam average intensity along the propagation path are derived. Strehl ratio of the received beam induced by intensity disorderly distribution and power efficiency of the received beam are introduced to evaluate performance of the optical system. Under the H-V 5/7 atmospheric turbulent model, performance of an optical system with determinate parameters was calculated, and the influences of the propagation distance and the laser wavelength were numerically analyzed, respectively. 相似文献