全文获取类型
收费全文 | 25805篇 |
免费 | 4345篇 |
国内免费 | 3996篇 |
专业分类
化学 | 20010篇 |
晶体学 | 424篇 |
力学 | 1273篇 |
综合类 | 296篇 |
数学 | 2944篇 |
物理学 | 9199篇 |
出版年
2024年 | 24篇 |
2023年 | 464篇 |
2022年 | 610篇 |
2021年 | 838篇 |
2020年 | 1042篇 |
2019年 | 1106篇 |
2018年 | 913篇 |
2017年 | 964篇 |
2016年 | 1252篇 |
2015年 | 1268篇 |
2014年 | 1613篇 |
2013年 | 2026篇 |
2012年 | 2429篇 |
2011年 | 2544篇 |
2010年 | 1952篇 |
2009年 | 1840篇 |
2008年 | 1952篇 |
2007年 | 1803篇 |
2006年 | 1685篇 |
2005年 | 1350篇 |
2004年 | 987篇 |
2003年 | 777篇 |
2002年 | 714篇 |
2001年 | 625篇 |
2000年 | 547篇 |
1999年 | 471篇 |
1998年 | 345篇 |
1997年 | 295篇 |
1996年 | 249篇 |
1995年 | 250篇 |
1994年 | 231篇 |
1993年 | 165篇 |
1992年 | 140篇 |
1991年 | 135篇 |
1990年 | 121篇 |
1989年 | 88篇 |
1988年 | 72篇 |
1987年 | 52篇 |
1986年 | 60篇 |
1985年 | 49篇 |
1984年 | 18篇 |
1983年 | 18篇 |
1982年 | 18篇 |
1981年 | 6篇 |
1980年 | 6篇 |
1979年 | 8篇 |
1973年 | 2篇 |
1971年 | 4篇 |
1957年 | 4篇 |
1936年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
Dual‐signal amplification strategy for ultrasensitive chemiluminescence detection of PDGF–BB in capillary electrophoresis 下载免费PDF全文
Jun‐Tao Cao Hui Wang Shu‐Wei Ren Yong‐Hong Chen Yan‐Ming Liu 《Biomedical chromatography : BMC》2015,29(12):1866-1870
Many efforts have been made toward the achievement of high sensitivity in capillary electrophoresis coupled with chemiluminescence detection (CE‐CL). This work describes a novel dual‐signal amplification strategy for highly specific and ultrasensitive CL detection of human platelet‐derived growth factor–BB (PDGF–BB) using both aptamer and horseradish peroxidase (HRP) modified gold nanoparticles (HRP–AuNPs–aptamer) as nanoprobes in CE. Both AuNPs and HRP in the nanoprobes could amplify the CL signals in the luminol–H2O2 CL system, owing to the excellent catalytic behavior of AuNPs and HRP in the CL system. Meanwhile, the high affinity of aptamer modified on the AuNPs allows detection with high specificity. As proof‐of‐concept, the proposed method was employed to quantify the concentration of PDGF–BB from 0.50 to 250 fm with a detection limit of 0.21 fm. The applicability of the assay was further demonstrated in the analysis of PDGF–BB in human serum samples with acceptable accuracy and reliability. The result of this study exhibits distinct advantages, such as high sensitivity, good specificity, simplicity, and very small sample consumption. The good performances of the proposed strategy provide a powerful avenue for ultrasensitive detection of rare proteins in biological sample, showing great promise in biochemical analysis. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
62.
Benzyl protecting protocol was first employed in two routes for the concise synthesis of dopexamine dihydrochloride.This protecting group could be cleanly removed under mild condition and no unacceptable ion was brought to the final product.The total yield of route I was 43.8% from phenylacetic acid,while it was 54.1% of route II from 2-(3,4-bis(benzyloxy)phenyl)acetic acid.The titration purity of the final product was more than 99.5%,while any single or total impurities met the known standard of the drug by HPLC analysis.The measured residual palladium met an acceptable limit(<1 ppm) as an API for injection. 相似文献
63.
64.
65.
66.
67.
68.
69.
70.