全文获取类型
收费全文 | 8289篇 |
免费 | 1439篇 |
国内免费 | 1526篇 |
专业分类
化学 | 6410篇 |
晶体学 | 155篇 |
力学 | 446篇 |
综合类 | 116篇 |
数学 | 939篇 |
物理学 | 3188篇 |
出版年
2024年 | 32篇 |
2023年 | 140篇 |
2022年 | 293篇 |
2021年 | 317篇 |
2020年 | 374篇 |
2019年 | 398篇 |
2018年 | 328篇 |
2017年 | 311篇 |
2016年 | 413篇 |
2015年 | 469篇 |
2014年 | 529篇 |
2013年 | 643篇 |
2012年 | 714篇 |
2011年 | 731篇 |
2010年 | 571篇 |
2009年 | 578篇 |
2008年 | 609篇 |
2007年 | 540篇 |
2006年 | 494篇 |
2005年 | 441篇 |
2004年 | 343篇 |
2003年 | 233篇 |
2002年 | 291篇 |
2001年 | 222篇 |
2000年 | 164篇 |
1999年 | 203篇 |
1998年 | 127篇 |
1997年 | 133篇 |
1996年 | 136篇 |
1995年 | 112篇 |
1994年 | 92篇 |
1993年 | 72篇 |
1992年 | 43篇 |
1991年 | 41篇 |
1990年 | 32篇 |
1989年 | 19篇 |
1988年 | 16篇 |
1987年 | 10篇 |
1986年 | 9篇 |
1985年 | 4篇 |
1984年 | 6篇 |
1983年 | 6篇 |
1982年 | 2篇 |
1981年 | 2篇 |
1980年 | 3篇 |
1975年 | 1篇 |
1965年 | 3篇 |
1959年 | 1篇 |
1936年 | 1篇 |
1909年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 1 毫秒
11.
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
12.
Three-dimensional (3-D) ZnO random-wall nanostructures and one-dimensional (1-D) ZnO nanorods were prepared on silicon substrates by a simple solid-vapour phase thermal sublimation technique. Optical pumped random lasing has been observed in the ZnO random-wall arrays with a threshold intensity of 0.38 MW/cm2 in the emission wavelength from 380 to 395 nm. The optical gain was attributed to the closed-loop scattering and light amplification of the ZnO random-wall. The experimental result suggests that the morphology of nanostructure is the key factor to effect random lasing. 相似文献
13.
本文以磁荷、磁极相互作用的库仑定律、电流元可作为产生磁场的源及牛顿第三定律为出发点 ,简单推导出毕奥 萨伐尔定律 相似文献
14.
本文简要介绍线性代数学习网站的系统研究与开发设计.涉及到网络数据库、ASP、界面设计等多种技术.该线性代数网上学习系统为老师和学生提供了交流平台,其界面美观、操作简便.具有良好的应用前景. 相似文献
15.
Miao Changxing 《数学学报(英文版)》1997,13(2):247-268
We consider the scattering problem for the Hartree equation with potential |x|−1 in a space of dimensionn≥2. We prove the existence ofH
m
-modified wave operator for Hartree equation on a dense set of a neighborhood of zero inH
m
(ℝ
n
), meanwhile, we obtain also the global existence for the Cauchy problem of Hartree equation in a space of dimensionn≥2.
This project is supported by the National Natural Science Foundation of China, 19601005 相似文献
16.
17.
提出了单层光学薄膜中薄膜与衬底反射光之间的双重干涉效应的理论,实验结果证实了理论分析的正确性。双重干涉效应使薄膜-衬底体系的热致反射调制度高达80%,这一效应可望有极广泛的应用 相似文献
18.
The kinetics of complexation reaction of Cu(II) with 9-ethyl-3-carbazolecarboxaldehyde-thiosemicarbazone (ECCAT) has been
examined spectrophotometrically. The ligand was synthesized for the first time. The complexation reaction was carried out
in a DMF-water medium at 35°C. The complex has maximum absorbance at 393 nm. Kinetic and activation parameters of the complexation
reaction were calculated by the Arrhenius and Eyring equations using the data obtained from investigating the effect of temperature
on reaction rates under the specified conditions. We also proposed reaction rate equations. Based on the studied complexation
reaction, a simple kinetic method for the spectrophotometric determination of copper(II) has been developed. The calibration
graphs are linear in the concentration range 0.2–1.9 μg/mL. The species that caused interference were investigated.
The text was submitted by the authors in English. 相似文献
19.
Ionic-liquid-supported peptide synthesis demonstrated by the synthesis of Leu(5)-enkephalin 总被引:1,自引:0,他引:1
A new strategy for the synthesis of oligopeptides was developed using an ionic liquid as a soluble support. The efficiency of this ionic liquid-phase approach was demonstrated by the synthesis of a bioactive pentapeptide, Leu(5)-enkephalin, in good yield and reasonable purity. The structures and purities of the reaction intermediates in each step were verified easily by routine spectroscopic analysis, and no chromatographic procedures were needed during the synthesis. 相似文献
20.
On bandwidth sums of graphs 总被引:1,自引:0,他引:1
ONBANDWIDTHSUMSOFGRAPHSYAOBING(姚兵);WANGJIANFANG(王建方)(DepartmentofMathematics,NorihwesteternNormalUniversity,Lanzhou730070,Chi... 相似文献