全文获取类型
收费全文 | 493634篇 |
免费 | 6737篇 |
国内免费 | 1693篇 |
专业分类
化学 | 262642篇 |
晶体学 | 7186篇 |
力学 | 21224篇 |
综合类 | 16篇 |
数学 | 60536篇 |
物理学 | 150460篇 |
出版年
2021年 | 3383篇 |
2020年 | 3939篇 |
2019年 | 4029篇 |
2018年 | 4776篇 |
2017年 | 4600篇 |
2016年 | 7897篇 |
2015年 | 5657篇 |
2014年 | 8046篇 |
2013年 | 22478篇 |
2012年 | 17428篇 |
2011年 | 21241篇 |
2010年 | 13846篇 |
2009年 | 13657篇 |
2008年 | 19364篇 |
2007年 | 19636篇 |
2006年 | 18906篇 |
2005年 | 17026篇 |
2004年 | 15505篇 |
2003年 | 13631篇 |
2002年 | 13256篇 |
2001年 | 14809篇 |
2000年 | 11498篇 |
1999年 | 9037篇 |
1998年 | 7313篇 |
1997年 | 7199篇 |
1996年 | 7115篇 |
1995年 | 6539篇 |
1994年 | 6238篇 |
1993年 | 6044篇 |
1992年 | 6772篇 |
1991年 | 6457篇 |
1990年 | 6196篇 |
1989年 | 5867篇 |
1988年 | 6101篇 |
1987年 | 5874篇 |
1986年 | 5531篇 |
1985年 | 7829篇 |
1984年 | 8032篇 |
1983年 | 6552篇 |
1982年 | 7075篇 |
1981年 | 7046篇 |
1980年 | 6729篇 |
1979年 | 6853篇 |
1978年 | 7002篇 |
1977年 | 7001篇 |
1976年 | 6976篇 |
1975年 | 6703篇 |
1974年 | 6570篇 |
1973年 | 6737篇 |
1972年 | 4082篇 |
排序方式: 共有10000条查询结果,搜索用时 296 毫秒
71.
Journal of Sol-Gel Science and Technology - Multifunctional magnetic mesoporous nanocomposites are promising materials to remove the various pollutants from water due to the remarkable properties... 相似文献
72.
Elasasy M. E. A. Elnaggar D. H. Hafez N. A. Abdel Azab M. E. Amr A. E. Omran M. M. Mohamed A. M. 《Russian Journal of General Chemistry》2021,91(5):915-925
Russian Journal of General Chemistry - Some new fluoro-heterocyclic compounds containing thiazole and pyridine moities have been synthesized and studied for their antiproliferative activity.... 相似文献
73.
Colloid Journal - An Erratum to this paper has been published: https://doi.org/10.1134/S1061933X21330024 相似文献
74.
Henry Dring David Kreutzer Christoph Ritter Andreas Hilgeroth 《Molecules (Basel, Switzerland)》2021,26(1)
Despite the development of targeted therapies in cancer, the problem of multidrug resistance (MDR) is still unsolved. Most patients with metastatic cancer die from MDR. Transmembrane efflux pumps as the main cause of MDR have been addressed by developed inhibitors, but early inhibitors of the most prominent and longest known efflux pump P-glycoprotein (P-gp) were disappointing. Those inhibitors have been used without knowledge about the expression of P-gp by the treated tumor. Therefore the use of inhibitors of transmembrane efflux pumps in clinical settings is reconsidered as a promising strategy in the case of the respective efflux pump expression. We discovered novel symmetric inhibitors of the symmetric efflux pump MRP4 encoded by the ABCC4 gene. MRP4 is involved in many kinds of cancer with resistance to anticancer drugs. All compounds showed better activities than the best known MRP4 inhibitor MK571 in an MRP4-overexpressing cell line assay, and the activities could be related to the various substitution patterns of aromatic residues within the symmetric molecular framework. One of the best compounds was demonstrated to overcome the MRP4-mediated resistance in the cell line model to restore the anticancer drug sensitivity as a proof of concept. 相似文献
75.
Farsi R. Mohammadi M. K. Saghanezhad S. J. 《Russian Journal of Organic Chemistry》2021,57(12):2002-2009
Russian Journal of Organic Chemistry - Herein, we report the sulfonamide-functionalized covalent organic framework (COF-SO3H), prepared by condensation of melamine and terephthalaldehyde and... 相似文献
76.
77.
Timm Bergholz Dr. Benjamin Oelkers Dr. Benedikt Huber Prof. Bernhard Roling Prof. Dr. Jörg Sundermeyer 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(6):2613-2620
New salts based on imidazolium, pyrrolidinium, phosphonium, guanidinium, and ammonium cations together with the 5‐cyanotetrazolide anion [C2N5]? are reported. Depending on the nature of cation–anion interactions, characterized by XRD, the ionic liquids (ILs) have a low viscosity and are liquid at room temperature or have higher melting temperatures. Thermogravimetric analysis, cyclic voltammetry, viscosimetry, and impedance spectroscopy display a thermal stability up to 230 °C, an electrochemical window of 4.5 V, a viscosity of 25 mPa s at 20 °C, and an ionic conductivity of 5.4 mS cm?1 at 20 °C for the IL 1‐butyl‐1‐methylpyrrolidinium 5‐cyanotetrazolide [BMPyr][C2N5]. On the basis of these results, the synthesized compounds are promising electrolytes for lithium‐ion batteries. 相似文献
78.
79.
80.