全文获取类型
收费全文 | 81749篇 |
免费 | 10505篇 |
国内免费 | 2748篇 |
专业分类
化学 | 81186篇 |
晶体学 | 877篇 |
力学 | 1745篇 |
综合类 | 119篇 |
数学 | 5826篇 |
物理学 | 5249篇 |
出版年
2024年 | 15篇 |
2023年 | 211篇 |
2022年 | 424篇 |
2021年 | 513篇 |
2020年 | 891篇 |
2019年 | 2699篇 |
2018年 | 2579篇 |
2017年 | 3194篇 |
2016年 | 3533篇 |
2015年 | 5803篇 |
2014年 | 5435篇 |
2013年 | 7548篇 |
2012年 | 6624篇 |
2011年 | 6132篇 |
2010年 | 5083篇 |
2009年 | 5052篇 |
2008年 | 4960篇 |
2007年 | 4569篇 |
2006年 | 4195篇 |
2005年 | 4038篇 |
2004年 | 3416篇 |
2003年 | 3017篇 |
2002年 | 3651篇 |
2001年 | 2021篇 |
2000年 | 1915篇 |
1999年 | 1107篇 |
1998年 | 501篇 |
1997年 | 548篇 |
1996年 | 480篇 |
1995年 | 497篇 |
1994年 | 421篇 |
1993年 | 344篇 |
1992年 | 253篇 |
1991年 | 328篇 |
1990年 | 294篇 |
1989年 | 264篇 |
1988年 | 360篇 |
1987年 | 355篇 |
1986年 | 278篇 |
1985年 | 263篇 |
1984年 | 276篇 |
1983年 | 143篇 |
1982年 | 243篇 |
1981年 | 190篇 |
1980年 | 158篇 |
1979年 | 148篇 |
1978年 | 21篇 |
1975年 | 3篇 |
1970年 | 2篇 |
1959年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
2.
3.
4.
对由一类非线性抛物型变分不等方程所描述的无穷维动力系统,给出了存在全局吸引子及弱近似惯性流形的充分条件. 相似文献
5.
Summary Experiments and simulations prove that correlation chromatography can greatly reduce the disadvantage of a non-linear response of the chromatographic column. A factor that has been accepted as being an important source of error in correlation or multiplex chromatography, has been shown not to be. Separations affected, improve dramatically when correlation chromatography is used, and a substantial amount of correlation noise only arises when there is a large difference in separation between a conventional chromatogram and a correlogram.A model has been developed for simulating these nonlinearities. It is shown that, especially for correlation chromatography, the simulation results match the practical measurements very well. 相似文献
6.
7.
5‐Amino‐4‐methyl‐2‐phenyl‐6‐substitutedfuro[2,3‐d]pyrimidines ( 2a‐c ) were reacted with 2,5‐dimethoxytetrahydrfuran to afford the pyrrolyl derivatives 3a‐c . Compound 3a was chosen as intermediate for the synthesis of poly fused heterocycles incorporated furopyrimidines moiety 4–11 . Some of the synthesized compounds were screened for their antibacterial and antifungal activities. 相似文献
8.
I. L. Davies K. E. Markides M. L. Lee M. W. Raynor K. D. Bartle 《Journal of separation science》1989,12(4):193-207
Although coupled liquid chromatographygas chromatography (LC-GC) was first demonstrated ten years ago, only in the last few years has there been a sudden surge of interest in the technique. Approximately 70% of the total number of LC-GC applications have been published in the last two years (1987–88) alone. This review categorizes LC-GC publications into four main application areas: fossil fuels, foods, environmental samples, biologiical/pharmaceutical samples, and miscellaneous samples. Multidimensional separations carried out using other coupled-column chromatographic techniques (such as supercritical fluid chromatography (SFC) with GC, and on-line trace enrichment-GC) have also been included in this review. 相似文献
9.
10.
Let G=(V(G),E(G)) be a graph. A (n,G, λ)‐GD is a partition of the edges of λKn into subgraphs (G‐blocks), each of which is isomorphic to G. The (n,G,λ)‐GD is named as graph design for G or G‐decomposition. The large set of (n,G,λ)‐GD is denoted by (n,G,λ)‐LGD. In this work, we obtain the existence spectrum of (n,P3,λ)‐LGD. © 2002 Wiley Periodicals, Inc. J Combin Designs 10: 151–159, 2002; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/jcd.10008 相似文献