全文获取类型
收费全文 | 11061篇 |
免费 | 1802篇 |
国内免费 | 1209篇 |
专业分类
化学 | 8161篇 |
晶体学 | 103篇 |
力学 | 598篇 |
综合类 | 82篇 |
数学 | 1394篇 |
物理学 | 3734篇 |
出版年
2024年 | 27篇 |
2023年 | 225篇 |
2022年 | 414篇 |
2021年 | 415篇 |
2020年 | 534篇 |
2019年 | 481篇 |
2018年 | 414篇 |
2017年 | 349篇 |
2016年 | 515篇 |
2015年 | 519篇 |
2014年 | 651篇 |
2013年 | 811篇 |
2012年 | 921篇 |
2011年 | 967篇 |
2010年 | 649篇 |
2009年 | 609篇 |
2008年 | 616篇 |
2007年 | 572篇 |
2006年 | 574篇 |
2005年 | 462篇 |
2004年 | 397篇 |
2003年 | 346篇 |
2002年 | 433篇 |
2001年 | 298篇 |
2000年 | 257篇 |
1999年 | 246篇 |
1998年 | 153篇 |
1997年 | 150篇 |
1996年 | 162篇 |
1995年 | 133篇 |
1994年 | 121篇 |
1993年 | 81篇 |
1992年 | 90篇 |
1991年 | 70篇 |
1990年 | 63篇 |
1989年 | 49篇 |
1988年 | 51篇 |
1987年 | 27篇 |
1986年 | 31篇 |
1985年 | 41篇 |
1984年 | 19篇 |
1983年 | 13篇 |
1982年 | 10篇 |
1981年 | 16篇 |
1980年 | 10篇 |
1979年 | 7篇 |
1977年 | 9篇 |
1976年 | 9篇 |
1975年 | 5篇 |
1974年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
31.
Wang Jingxiu Zhang Jun Deng Yuanyong Li Jingqun Tian Lirong Yang Xiulan 《中国科学A辑(英文版)》2002,45(1):57-64
Based on the studies on the source regions of a group of coronal mass ejections, we have identified two types of large-scale magnetic structures, and suggested that they are intrinsic components of solar magnetism, their destabilization, expansion, and eruption into the interplanetary space are the basic physical processes which lead to the coronal mass ejections. These two types of large-scale structures are giant magnetic loops connecting the two active belts on the opposite hemispheres of the Sun, and the giant filaments (filament channels) and their related magnetic structures. The latter often appear as two parallel rows of sunspots and plage fields, which align side by side in the full disk daily and synoptic magnetograms. The magnetic neutral lines of these large-scale structures are usually longer than 50 heliographic degrees. We name this type of structure “super A configuration”. Sometimes, they are shown as very long filaments and related large-scale magnetic fields. As these magnetic structures are of very large scale, they extend to a great altitude into the corona, they are not easily recognized in magnetic field observations which are usually aimed at solar flare studies. To identify these large-scale structures becomes a key to understanding and predicting coronal mass ejections. 相似文献
32.
A graph G is 3‐domination critical if its domination number γ is 3 and the addition of any edge decreases γ by 1. Let G be a 3‐connected 3‐domination critical graph of order n. In this paper, we show that there is a path of length at least n?2 between any two distinct vertices in G and the lower bound is sharp. © 2002 John Wiley & Sons, Inc. J Graph Theory 39: 76–85, 2002 相似文献
33.
M. Alves Da Silva M. Helena Gil A. P. Piedade J. S. Redinha A. M. Oliveira Brett J. M. Caridade Costa 《Journal of polymer science. Part A, Polymer chemistry》1991,29(2):269-274
The immobilization of catalase on grafted membranes of poly(ethylene)-g-co-acrylic acid and poly(tetrafluoroethylene)-g-co-acrylic acid and their application in hydrogen peroxide electrochemical sensors is described. The introduction of carboxylic acid groups onto a hydrophobic support provides a good environment for subsequent enzyme immobilization. This single membrane, hydrogen peroxide sensor showed significant improvement with respect to the double membrane versions. The response is very rapid, the linear range being from 10 μM up to 6 mM, with a detection limit of 4.7 μM, and a lifetime of more than 4 months. 相似文献
34.
扰动周期KdV方程的小波基分析 总被引:2,自引:2,他引:0
本文利用样条小波基构造近似惯性流形来研究扰动周期KdV方程的长期动力学行为· 相似文献
35.
1引言 2006年3月 高等学校计算数学学报 设f(x)为卜1,1}上的连续函数,则以第二类Chebyshev多项式认(x)(Un(eoso)= 烈共坐)的全部零点{ 乙工工1口 式为 其中 k x无=Cos了一下丁7r 了L十1 犷_,为插值结点组的了的Gr如wald插值多项 G。(,,x)=艺了(x、)‘孟(x), n. 11 一一 k 相似文献
36.
Yan Shun MA Qing Hua MENG Hong Yu SHI Yuan De LONG Tian Bao HUANG 《中国化学快报》2006,17(6):807-808
Dencichine (β-N-oxalyl-L-α, β-diaminopropionic acid, L-ODAP), a nonprotein amino acid, is a haemostatic agent present in important Chinese medicinal herbs such as Panax notoginseng, as well as other Panax species1. It was first isolated from the seeds … 相似文献
37.
YBa2Cu3O7-δ and Tl2Ba2CaCu2O8 thin films for microwave filters were synthesized by pulsed laser deposition and the two-step thalliation process. Substrate
quality requirements and the relation of thin film morphology, microstructure with microwave surface resistance were discussed. 相似文献
38.
通过考虑同类核子相干对间的四极相互作用,在IBM2中对Ce偶-偶同位素^128Ce-^138Ce的低激发态能谱和E2跃迁几率及分支比进行了理论分析,计算结果有效地改善了IBM中这些核的γ带能谱的Staggering现象描述,与实验观察到的低激发态结果基本一致。 相似文献
39.
40.
Triterpenoid Constituents of Huperzia miyoshiana 总被引:1,自引:0,他引:1
Thirteen triterpenoids, including three new ones, miyoshianois A (1), B (2) and C (3), were isolated from Huperzia miyoshiana. The structures of these new compounds were established as 3-O-dihydroferuloyltohogenol (1), 16-oxo-3β,21β-dihydrox-y-serrat-14-en-24-ferulate (2) and 16-oxo-3a, 21β-dihydroxy-serrat-14-en-24-ferulate (3), respectively, on the basis of their spectroscopic analysis. 相似文献