全文获取类型
收费全文 | 14930篇 |
免费 | 2591篇 |
国内免费 | 2893篇 |
专业分类
化学 | 15309篇 |
晶体学 | 172篇 |
力学 | 421篇 |
综合类 | 108篇 |
数学 | 291篇 |
物理学 | 4113篇 |
出版年
2024年 | 54篇 |
2023年 | 247篇 |
2022年 | 644篇 |
2021年 | 712篇 |
2020年 | 952篇 |
2019年 | 736篇 |
2018年 | 613篇 |
2017年 | 750篇 |
2016年 | 921篇 |
2015年 | 891篇 |
2014年 | 1020篇 |
2013年 | 1539篇 |
2012年 | 1099篇 |
2011年 | 1136篇 |
2010年 | 903篇 |
2009年 | 950篇 |
2008年 | 965篇 |
2007年 | 917篇 |
2006年 | 773篇 |
2005年 | 746篇 |
2004年 | 719篇 |
2003年 | 551篇 |
2002年 | 437篇 |
2001年 | 333篇 |
2000年 | 268篇 |
1999年 | 250篇 |
1998年 | 237篇 |
1997年 | 187篇 |
1996年 | 165篇 |
1995年 | 150篇 |
1994年 | 115篇 |
1993年 | 124篇 |
1992年 | 58篇 |
1991年 | 46篇 |
1990年 | 37篇 |
1989年 | 26篇 |
1988年 | 25篇 |
1987年 | 25篇 |
1986年 | 14篇 |
1985年 | 10篇 |
1984年 | 13篇 |
1983年 | 10篇 |
1982年 | 10篇 |
1981年 | 7篇 |
1980年 | 5篇 |
1979年 | 7篇 |
1977年 | 3篇 |
1976年 | 3篇 |
1975年 | 3篇 |
1972年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
51.
T. Mihara K. Miyamoto M. Kida T. Sasaki N. Aoki Y. Ochiai 《Superlattices and Microstructures》2003,34(3-6):383
A multiwall carbon nanotube crossroads has been fabricated by a manipulation technique using a glass microcapillary, and the low temperature transport properties investigated. The two-terminal conductance of an individual tube shows Tomonaga–Luttinger liquid behavior G∝Tα at high temperature and dI/dV ∝V α at low temperature. However, no evidence of such a power-law behavior is obtained in the four-terminal conductance at the junction, where the conductance shows an almost metallic behavior ‘corrected’ by weak localization. Weak localization would essentially appear in electron states at the junctions of MWNTs. 相似文献
52.
53.
Qing Shi Dong Yang Yanlei Su Jian Li Zhongyi Jiang Yanjun Jiang Weikang Yuan 《Journal of nanoparticle research》2007,9(6):1205-1210
Lipase from Candida rugosa was covalently anchored onto acid-treated multi-walled carbon nanotubes (MWNTs) through a self-catalytic mechanism. A variety
of characterization techniques including FTIR, Raman spectroscopy, and XPS were employed to demonstrate the formation of the
ester linkage between lipase and MWNTs. The MWNTs-lipase biocomposites showed significantly increased solubility in some common-used
organic solvents, such as THF, DMF and chloroform. This study may offer a novel and facile route for covalent modification
of carbon nanotubes, and expand the potential utilization of both lipases and MWNTs in the fields of biocatalyst and biosensor. 相似文献
54.
湿度对绝缘体表面电导和气体电导有一定的影响,但通常在湿度传感器的研究中忽略了气体电导的贡献。本文通过特殊设计装置来区分表面电导和气体电导,并分别从实验和理论上进行了定性的研究。 相似文献
55.
Jindun Liu A. J. B. Kemperman G. H. Koops M. Wessling 《中国颗粒学报》2006,4(2):98-102
A novel method of fabricating composite mosaic membranes was studied on the basis of interracial polymerization (IP) by coating a thin selective layer onto the surface of a micro-porous hollow-fiber membrane, in which, 2,5-diaminobenzene sulfonic acid was used as one monomer of the IP reaction, and a mixture of trimesoyl chloride (TMCI) and 4-(chloromethyl) benzoyl chloride as the other monomer. Through the IP reaction a thin selective layer with negatively charged groups could be first formed on the polyethersulfone (PES) support membrane. Then trimethylamine solution was introduced to modify the IP layer through a quaternization reaction. Thus the selective layer of this composite membrane contained both negatively charged and positively charged groups to perform the mosaic functionality. Characterization of the composite mosaic membranes was carried out through permeation experiments using different inorganic salts and dyes. The experimental results showed that the membranes could permeate both mono- and bi-valent inorganic salts, but reject larger organic molecules. Such a mosaic membrane is potentially useful for the separation of salts from water-soluble organics, especially in dye and textile industries. 相似文献
56.
57.
58.
《Electroanalysis》2006,18(6):613-620
The interaction of malachite green (MG) with double‐stranded DNA (dsDNA) in pH 7.0 Britton–Robinson (B–R) buffer solution was investigated by electrochemical and spectrophotometric methods. Within the potential scan range of ?1.0 to +1.5 V (vs. SCE), MG has two oxidative peaks at 0.547 V and 0.833 V and one reductive peak at 0.362 V on cyclic voltammogram at the scan rate of 0.20 V/s. After the addition of dsDNA into the MG solution, the oxidative peak current at 0.547 V decreases obviously. The electrochemical parameters, such as the charge transfer coefficient (α), the surface reaction rate constant (ks) and the diffusion coefficient (D), were calculated and compared between in the absence and presence of dsDNA. The results show that these parameters of MG after adding dsDNA have greatly changed, which indicates that an electrochemical active complex was formed. The interaction mechanisms of MG with dsDNA are discussed in some details from the electrochemistry and UV‐vis spectrophotometry. The reduction of the peak current of MG after adding dsDNA was further used for the quantification of dsDNA by differential pulse voltammetry (DPV). The linear range for dsDNA is in the range of 10.0–100.0 μg/mL with the linear regression equation as Δip (μA)=0.065+0.0096 C (μg/mL) and the detection limit of 6.0 μg/mL (3σ). The influences of coexisting substances were investigated and artificial samples were determined with satisfactory results. 相似文献
59.
We have studied antimony and selenium atomization processes including a chemical matrix modifier (palladium-containing activated
carbon) during their determination by electrothermal atomic absorption spectrometry. We have developed and fine-tuned an experimental
setup for determining the kinetic characteristics (activation energy and frequency factor) for element atomization processes
from measurements in the initial section of the analytical signal. We provide a rationale for the most likely mechanism for
the interactions that occur. The results of the kinetic studies of the atomization processes showed that the modifier we developed
was highly effective, as a result of formation of a thermally stable condensed system C-Pd-A (where A is the analyte).
__________
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 4, pp. 530–534, July–August, 2006. 相似文献
60.