全文获取类型
收费全文 | 127468篇 |
免费 | 19823篇 |
国内免费 | 14790篇 |
专业分类
化学 | 90128篇 |
晶体学 | 1483篇 |
力学 | 7139篇 |
综合类 | 923篇 |
数学 | 16255篇 |
物理学 | 46153篇 |
出版年
2024年 | 284篇 |
2023年 | 2343篇 |
2022年 | 3648篇 |
2021年 | 4201篇 |
2020年 | 4842篇 |
2019年 | 4597篇 |
2018年 | 4253篇 |
2017年 | 3883篇 |
2016年 | 5757篇 |
2015年 | 5660篇 |
2014年 | 6941篇 |
2013年 | 9218篇 |
2012年 | 11072篇 |
2011年 | 11688篇 |
2010年 | 8191篇 |
2009年 | 7890篇 |
2008年 | 8478篇 |
2007年 | 7557篇 |
2006年 | 7081篇 |
2005年 | 5988篇 |
2004年 | 4680篇 |
2003年 | 3803篇 |
2002年 | 3574篇 |
2001年 | 2973篇 |
2000年 | 2574篇 |
1999年 | 2639篇 |
1998年 | 2246篇 |
1997年 | 1981篇 |
1996年 | 2045篇 |
1995年 | 1760篇 |
1994年 | 1604篇 |
1993年 | 1332篇 |
1992年 | 1214篇 |
1991年 | 1052篇 |
1990年 | 886篇 |
1989年 | 692篇 |
1988年 | 547篇 |
1987年 | 470篇 |
1986年 | 468篇 |
1985年 | 420篇 |
1984年 | 289篇 |
1983年 | 215篇 |
1982年 | 198篇 |
1981年 | 133篇 |
1980年 | 113篇 |
1979年 | 84篇 |
1978年 | 61篇 |
1976年 | 59篇 |
1975年 | 54篇 |
1973年 | 61篇 |
排序方式: 共有10000条查询结果,搜索用时 171 毫秒
971.
Zhao‐Peng Deng Shan Gao Li‐Hua Huo Hui Zhao 《Acta Crystallographica. Section C, Structural Chemistry》2007,63(5):m225-m227
In the title complex, [Mn(SO4)(C3H7NO)(H2O)2]n, each MnII ion has a distorted octahedral geometry formed by three O atoms of three different sulfate groups, one O atom of a dimethylformamide ligand and two water molecules. The sulfate groups act as tridentate bridging ligands connecting the MnII ions into a two‐dimensional layer structure which can be regraded as a 4.82 network. 相似文献
972.
973.
974.
Guan Wu WANG* Li Juan JIAO Er Hong HAO Yong Ming LU You Jun YANG Department of Chemistry University of Science Technology of China Hefei 《中国化学快报》2004,15(5)
Water-soluble fullerenes not only have a number of important applications in biological chemistry1, but also form ordered aggregate structures that can be utilized in materials science2. There are reports that some water-soluble fullerene derivatives can form ordered structures in water, such as vesicle, nanorod and nanoparticle2-5. However, relatively few reports on the aggregation process have been reported. Knowledge of factors that affect the cluster formation in solution is of consider… 相似文献
975.
X-ray absorption spectra of plasmas 总被引:1,自引:0,他引:1
In this paper we present a theoretical method to calculate the absorption spectra of hot dense plasmas. Based on our fully relativistic treatment incorporated with the quantum defect theory to handle the huge number of transition arrays from many configurations with high principal quantum number, we can calculate the absorption spectra for any element or multi-element plasmas with little computational efforts. We calculate the absorption spectra of C10H1605 plasmas, which are in good agreement with the experimental spectra. We can then provide diagnostic analysis for plasmas in relevant inertial confinement fusion (lCF) experiments; namely not only to determine plasmas' temperatures and densities, but also to provide the population densities of various ionic stages. Our theoretical method verified by "benchmark experiments" will be a basic tool to provide "precise" opacity data for the ICF research.`` 相似文献
976.
Jian-Shu Li 《Mathematische Annalen》1992,292(1):747-761
Supported in part by NSF grant No. DMS-9003999 相似文献
977.
用ESR方法研究了红薯淀粉在γ射线预辐照下,产生的淀粉自由基特性及其室温下的自由基衰减动力学反应。结果表明在室温条件下,淀粉自由基的相对浓度随辐射剂量的增大而增加。自由基相对浓度的室温衰减用二级反应动力学处理,求得了衰减速率常数和淀粉自由基反应的半衰期。 相似文献
978.
The black carbon aerosols are now recognized for their potential impact on climate and the halogenated compounds are thought to be very important in atmospheric chemistry. However, there are very few studies on the interactions between soot aerosols and halogenated compounds. We report the measurement of the uptake of CH3I on soot. The measured uptake coefficient is 0.0103 ± 0.0015 at a total pressure of 2–4 Torr and 298 K. The results suggest that the uptake of CH3I occurs efficiently on soot particles. The present work suggests that heterogeneous loss of CH3I on soot may influence the concentration of CH3I throughout the atmosphere. 相似文献
979.
Trirubidium diyttrium triborate contains zigzag chains of corner‐sharing [Y2O10] dimers. The chains are reinforced by one independent BO3 group and crosslinked by the other two types of BO3 groups to form a three‐dimensional framework. Channels along the [100] direction accommodate the Rb+ cations. 相似文献
980.
We reported controllable synthesis of ZnS nanocrystal-polymer transparent hybrids by using polymethylmethacrylate (PMMA) as
a polymer matrix. In a typical run, the appropriate amounts of zinc chloride (ZnCl2) and sodium sulfide (Na2S) in the presence of 2-mercaptoethanol (ME) as the organic ligand were well dispersed in H2O/dimethylformamide solution without any aggregation. In addition, the Mn-doped ZnS nanocrystals (NCs) were synthesized with
similar method. Then, ZnS-PMMA hybrids were obtained via free radical polymerization in situ by using ZnS NCs functionalized
with methacryloxypropyltrimethoxysilane (MPS). FT-IR characterization indicates the formation of robust bonding between ZnS
NCs and the organic ligand. The TEM images show that ZnS NCs are well dispersed in PMMA matrix, and particle size of as-prepared
ZnS NCs is about 2.6 nm, in agreement with the computing results of Brus’s model and Debye–Scherrer formula. The photoluminescence
measurements present that ZnS NCs, Mn-doped ZnS NCs, and ZnS/PMMA hybrid show good optical properties. 相似文献