全文获取类型
收费全文 | 17362篇 |
免费 | 3012篇 |
国内免费 | 2618篇 |
专业分类
化学 | 13560篇 |
晶体学 | 164篇 |
力学 | 1046篇 |
综合类 | 206篇 |
数学 | 1894篇 |
物理学 | 6122篇 |
出版年
2024年 | 36篇 |
2023年 | 375篇 |
2022年 | 390篇 |
2021年 | 551篇 |
2020年 | 772篇 |
2019年 | 686篇 |
2018年 | 610篇 |
2017年 | 503篇 |
2016年 | 831篇 |
2015年 | 782篇 |
2014年 | 1002篇 |
2013年 | 1288篇 |
2012年 | 1539篇 |
2011年 | 1609篇 |
2010年 | 1182篇 |
2009年 | 1132篇 |
2008年 | 1239篇 |
2007年 | 1070篇 |
2006年 | 972篇 |
2005年 | 866篇 |
2004年 | 753篇 |
2003年 | 633篇 |
2002年 | 651篇 |
2001年 | 521篇 |
2000年 | 463篇 |
1999年 | 430篇 |
1998年 | 321篇 |
1997年 | 258篇 |
1996年 | 280篇 |
1995年 | 242篇 |
1994年 | 178篇 |
1993年 | 163篇 |
1992年 | 133篇 |
1991年 | 103篇 |
1990年 | 109篇 |
1989年 | 68篇 |
1988年 | 62篇 |
1987年 | 56篇 |
1986年 | 36篇 |
1985年 | 32篇 |
1984年 | 16篇 |
1983年 | 10篇 |
1982年 | 15篇 |
1981年 | 10篇 |
1980年 | 6篇 |
1979年 | 3篇 |
1971年 | 1篇 |
1957年 | 2篇 |
1936年 | 1篇 |
1916年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 328 毫秒
31.
Existence, Multiplicity and Infinite Solvability of Positive Solutions for One-Dimensional p-Laplacian 总被引:5,自引:0,他引:5
Qing Liu YAO 《数学学报(英文版)》2005,21(4):691-698
The existence, multiplicity and infinite solvability of positive solutions are established for some two-point boundary value problems of one-dimensional p-Laplacian. In this paper, by multiplicity we mean the existence of m solutions, where m is an arbitrary natural number. 相似文献
32.
The first α‐diimine nickel(I) complex having a chloro bridge is reported. The centrosymmetric dinuclear structure of {[ArN?C(Me)C(Me)?NAr]NiCl}2[Ar?2,6?C6H3(i‐Pr)2] features two chelating α‐diimine ligands and two bridged chlorine atoms, so that a distorted tetrahedral N2Cl2 coordination geometry for nickel results. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
33.
A fluorous osmium catalyst was firstly developed. It had been effectively used as recoverable and reusable catalyst in the dihydroxylation of olefins. 相似文献
34.
室温下,通过双核配合物[Cu(dppm)(NO3)]2(dppm=双二苯基膦甲烷)与四苯基硼钠在甲醇和二氯甲烷混合溶剂中反应制备了三核铜(I)配合物[Cu3(dppm)3(NO3)(OH)](NO3),经过红外光谱、热重分析、核磁和ES-MS等现代分析手段表征了配合物的物理化学性质,并进一步研究了配合物在室温下的荧光光谱特征。 相似文献
35.
36.
In mononuclear HgI2[(C5H4N)3N], mercury is tetrahedrally coordinated by two nitrogen atoms of a tris(2‐pyridyl)amine ligand and two iodides. The coordination moieties are connected by weak intermolecular Hg(II)···I interactions to give a one‐dimensional structure. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
37.
38.
Xiao Qi ZHENG Yong Hui WANG Qing Xiang GUO* Li YANG You Cheng LIU Department of Chemistry University of Science Technology of China Hefei National Laboratory of Applied Organic Chemistry Lanzhou University Lanzhou 《中国化学快报》2003,(8)
As artificial enzymes, the binding constants of cyclodextrins (CDs) and their substrates are expected to be high1. For this purpose, many kinds of bridged cyclodextrin dimers2 whose two cyclodextrins are linked by various spacers have been constructed. It was of interest to make the dimers, whose binding constants would exceed 108dm3/mol3. Up to date, the bridged cyclodextrin dimers have been extensively studied as enzyme models and as molecular receptors4-6. Recently, we synthesized a brid… 相似文献
39.
40.
Ping Li Fei Rong Yibing Xie Van Hu Chunwei Yuan 《Journal of Analytical Chemistry》2004,59(10):939-944
S-naproxen imprinted polymer was prepared with acrylamide as a functional monomer, 1,4-butanediyl diacrylate as a new kind of crossliner, and 2,4,6-trimethylbenzoylphenyl-phosphinic acid ethyl ester as photoinitiator. Their UV and IR spectra were applied to study the interactions between the template and the monomer. Binding experiments showed that the S-naproxen imprinted polymer had better recognition capability for the template than that of a blank polymer. The adsorption distribution coefficient KD of S-naproxen on molecularly-imprinted polymer was 153.2 g/mL, and the separation factor was 1.95 when the initial concentration of substrate was 2.0 mmol/L. Scatchard curves suggested that there were two classes of binding sites in the imprinted polymer and only one class in the blank polymer. Computer simulation using Hyperchem showed the existence of the interactions between the template and the functional monomer as well as the models of the complexes formed by the template and the monomer. 相似文献