全文获取类型
收费全文 | 335972篇 |
免费 | 8072篇 |
国内免费 | 3682篇 |
专业分类
化学 | 186647篇 |
晶体学 | 4706篇 |
力学 | 14374篇 |
综合类 | 245篇 |
数学 | 38826篇 |
物理学 | 102928篇 |
出版年
2021年 | 2454篇 |
2020年 | 2925篇 |
2019年 | 2819篇 |
2018年 | 2688篇 |
2017年 | 2570篇 |
2016年 | 4894篇 |
2015年 | 4202篇 |
2014年 | 5618篇 |
2013年 | 15539篇 |
2012年 | 12672篇 |
2011年 | 15322篇 |
2010年 | 9600篇 |
2009年 | 9559篇 |
2008年 | 13770篇 |
2007年 | 13861篇 |
2006年 | 13430篇 |
2005年 | 12147篇 |
2004年 | 10807篇 |
2003年 | 9501篇 |
2002年 | 9273篇 |
2001年 | 10561篇 |
2000年 | 8174篇 |
1999年 | 6669篇 |
1998年 | 5352篇 |
1997年 | 5148篇 |
1996年 | 5190篇 |
1995年 | 4728篇 |
1994年 | 4459篇 |
1993年 | 4254篇 |
1992年 | 4685篇 |
1991年 | 4514篇 |
1990年 | 4238篇 |
1989年 | 3981篇 |
1988年 | 4235篇 |
1987年 | 3865篇 |
1986年 | 3772篇 |
1985年 | 5380篇 |
1984年 | 5432篇 |
1983年 | 4416篇 |
1982年 | 4786篇 |
1981年 | 4813篇 |
1980年 | 4551篇 |
1979年 | 4665篇 |
1978年 | 4665篇 |
1977年 | 4644篇 |
1976年 | 4597篇 |
1975年 | 4508篇 |
1974年 | 4356篇 |
1973年 | 4524篇 |
1972年 | 2569篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
Studies on metabolites and metabolic pathways of bulleyaconitine A in rat liver microsomes using LC‐MSn combined with specific inhibitors
下载免费PDF全文
![点击此处可从《Biomedical chromatography : BMC》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Hongbin Zhu Fengrui Song Zhiqiang Liu Shuying Liu 《Biomedical chromatography : BMC》2015,29(7):1027-1034
Bulleyaconitine A (BLA) from Aconitum bulleyanum plants is usually used as anti‐inflammatory drug in some Asian countries. It has a variety of bioactivities, and at the same time some toxicities. Since the bioactivities and toxicities of BLA are closely related to its metabolism, the metabolites and the metabolic pathways of BLA in rat liver microsomes were investigated by HPLC–MSn. In this research, the 12 metabolites of BLA were identified according to the results of HPLC‐MSn data and the relevant literature. The results showed that there are multiple metabolites of BLA in rat liver microsomes, including demethylation, deacetylation, dehydrogenation deacetylation and hydroxylation. The major metabolic pathways of BLA in rat liver microsomes were clarified by HPLC‐MS combined with specific inhibitors of CYP450 isoforms. As a result, CYP3A and 2C were found to be the principal CYP isoforms contributing to the metabolism of BLA. Moreover, CYP2D6 and 2E1 are also more important CYP isoforms for the metabolism of BLA. While CYP1A2 only affected the formation rate of M11, its effect on the metabolism of BLA is very small. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
72.
In this paper, we analyze the concentration behavior of a positive solution to an evolution equation with critical exponential growth on a closed Riemann surface, and particularly derive an energy identity for such a solution. This extends a result of Lamm-Robert-Struwe and complements that of Yang. 相似文献
73.
Ben Jadi S. El Guerraf A. Bazzaoui E.A. Wang R. Martins J.I. Bazzaoui M. 《Journal of Solid State Electrochemistry》2019,23(8):2423-2433
Journal of Solid State Electrochemistry - Due to their distinctive chemical, electronic, and environmental properties, polypyrrole is used as a blocking barrier for methanol leakage in direct... 相似文献
74.
Liying Zhang Chuanrui Zhao Yujiao Bai Qian Wang Pan Ma Xiaojie Ma Peihua Zhu 《Electroanalysis》2022,34(2):302-309
The design and exploration of efficient, stable and environmentally compatible organic emitters for an electrochemiluminescence (ECL) sensor is a promising topic. Herein, a novel environmentally-friendly luminophore, ZnBCBTP@MWCNTs, were fabricated via self-assembly of porphyrin molecules (ZnBCBTP) onto multi-walled carbon nanotubes (MWCNTs). The resulting luminophore ZnBCBTP@MWCNTs displayed not only the highly ECL property and but also the good accelerated electron mobility. Then, a label-free ECL biosensor based ZnBCBTP@MWCNTs was constructed for the ultrasensitive detection of uric acid. Excitingly, this proposed ECL biosensor performed a good linear relationship in the range of 0–300 μM with a low detection limit of 1.4 μM, thus offering another reliable and feasible sensing platform for clinical bioanalysis with good selectivity, stability, and repeatability. 相似文献
75.
Kounta Moussa Dawson Nathan J. 《Methodology and Computing in Applied Probability》2021,23(3):1155-1172
Methodology and Computing in Applied Probability - The problem of optimally controlling one-dimensional diffusion processes until they enter a given stopping set is extended to include Markov... 相似文献
76.
Jia Tian-Cong Guo Jin-Tao Wang Zhen Zhu Xiao-Shan Zhang Qian-Xin Chen Ping Yao Kun Lv Wen-Ying Liu Guo-Guang 《Journal of Radioanalytical and Nuclear Chemistry》2019,321(3):823-829
Journal of Radioanalytical and Nuclear Chemistry - In the present work the final products of coumarin radiation chemical transformation are investigated by chromatography. During radiolysis of... 相似文献
77.
78.
79.
Ding Q. Yao M. Wu Sh. Zeng M. Xue N. Wu D. Xu J. 《Journal of Applied Spectroscopy》2022,89(4):712-718
Journal of Applied Spectroscopy - Based on partial least squares (PLS) analysis, the effects of different smoothing points and different preprocessing methods on the accuracy and precision of the... 相似文献
80.
Transport in Porous Media - The theme of coupling problems for adsorption, absorption and thermochemical transport in porous media is very important for engineering applications. Based on the... 相似文献