全文获取类型
收费全文 | 7554篇 |
免费 | 1367篇 |
国内免费 | 1244篇 |
专业分类
化学 | 6200篇 |
晶体学 | 83篇 |
力学 | 404篇 |
综合类 | 85篇 |
数学 | 834篇 |
物理学 | 2559篇 |
出版年
2024年 | 16篇 |
2023年 | 146篇 |
2022年 | 295篇 |
2021年 | 306篇 |
2020年 | 369篇 |
2019年 | 424篇 |
2018年 | 311篇 |
2017年 | 289篇 |
2016年 | 401篇 |
2015年 | 423篇 |
2014年 | 464篇 |
2013年 | 591篇 |
2012年 | 721篇 |
2011年 | 687篇 |
2010年 | 428篇 |
2009年 | 431篇 |
2008年 | 479篇 |
2007年 | 383篇 |
2006年 | 374篇 |
2005年 | 330篇 |
2004年 | 286篇 |
2003年 | 249篇 |
2002年 | 335篇 |
2001年 | 274篇 |
2000年 | 173篇 |
1999年 | 157篇 |
1998年 | 132篇 |
1997年 | 77篇 |
1996年 | 91篇 |
1995年 | 65篇 |
1994年 | 68篇 |
1993年 | 53篇 |
1992年 | 78篇 |
1991年 | 53篇 |
1990年 | 52篇 |
1989年 | 32篇 |
1988年 | 22篇 |
1987年 | 24篇 |
1986年 | 26篇 |
1985年 | 15篇 |
1984年 | 8篇 |
1983年 | 11篇 |
1982年 | 2篇 |
1981年 | 4篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1971年 | 1篇 |
1959年 | 2篇 |
1957年 | 2篇 |
1936年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
941.
942.
The thermal decomposition behavior of double‐base rocket propellant SQ‐2 was studied by a Calvet microcalorimeter at four different heating rates. The kinetic and thermodynamic parameters were obtained from the analysis of the heat flow curves. The critical temperature of thermal explosion (Tb), the self acceleration decomposition temperature (TSADT), the adiabatic decomposition temperature rise (ΔTad), the time‐to‐explosion of adiabatic system (t), critical temperature of hot‐spot initiation (Tcr), critical thermal explosion ambient temperature (Tacr), safety degree (SD) and thermal explosive probability (PTE) were presented to evaluate the thermal hazard of SQ‐2. 相似文献
943.
Inorganic layered materials are a class of advanced functional materials that have attracted considerable attention by virtue of their practical applications in a wide variety of fields. Sys-tematic studies of structure, design, synthesis, and fabrication processing may extend the range of practical utility of inor-ganic layered functional materials, in areas such as food industry,chemical industry, energy engineering, environmental engineer-ing, drug and gene delivery, electronics technology, and materials protection. 相似文献
944.
945.
Yan Ling ZHANG Wei Sheng LIU Yang LI Xue Yi MA* Yao Zu CHEN National Laboratory of Applied Organic Chemistry Department of Chemistry Lanzhou University Lanzhou Department of Chemistry Zhejiang University Hangzhou 《中国化学快报》2001,(4)
The importance of Vitamin A for human health has been stressed in resent studies1, meanwhile its derivative so-called retinoic acid (RA) has been widely used as pharmaceutical to treat several types of skin disease and cancer2,3. However the application of retinoic acid is restrained for its poor water solubility, unstability and side effect on the human body.Cyclodextrins (CDs) are macrocyclic oligosaccharides built up from 6, 7, or 8 glucopyranose units called (, (, and (-CD, respectively… 相似文献
946.
F. Pan M.-X. Xie J.-J. Lin X.-G. Xue J. P. Draayer 《The European Physical Journal B - Condensed Matter and Complex Systems》2009,72(4):479-484
The one-dimensional t-J
model Hamiltonian is realized by using hard-core boson operators. A
simple algorithm written in Mathematica based on a differential
realization of the hard-core bosons for finding exact solutions of
the model is proposed. As a simple example, some low-lying
excitation energies, the inverse compressibility, and the
superconducting structure factors, as well as the particle and spin
entanglement of a system with 8 sites are calculated. The results
not only confirm the validity of the hard-core boson picture, but
also indicate that a quantum phase transition near phase-separation
at zero temperature can also be recognized by the particle and spin
entanglement. 相似文献
947.
To investigate the effect of photodynamic therapy (PDT) with hematoporphrin monomethyl ether (HMME) on bovine immunodeficiency virus (BIV) can provide the basis theory for photoinactivation of human immunodeficiency virus (HIV). To assess the protection of HMME-PDT on the cell line Cf2Th infected with BIVR29 by 3-(4,5)-dimethylthiahiazol-2-yl-3,5-di-phenytetrazolium bromide (MTT) with power density of 5 and 25 mW/cm2 and energy density from 0.6 to 3 J/cm<'2>. To observe the inhibition of membrane fusion using a new reporter cell line BIVE by fluorescence microscope. HMME-PDT has significant protectant effects on Cf2Th-BIVR29 with both power densities, especially in the group of high power density. Fluorescent microscope shows that there is no significant difference between the group of PDT and control, which means PDT could not inhibit the BIV-mediated membrane fusion. 相似文献
948.
利用脉宽为25ns的脉冲Nd:YAG 532 nm的激光,在8×1010W/cm2的强度下,用飞行时间质谱对CS2的激光电离过程进行了研究.观察到了较强的C2+和S2+高价离子信号,这些高价离子C2+,S2+的最可几平动能高达144eV,112 eV.不同进样方式,激光延迟以及束源压力的实验结果表明,这些高价离子可能来源于CS2团簇的库仑爆炸过程.多光子电离引发,逆韧致吸收加热-电子碰撞电离模型可能是高价离子产生的机理. 相似文献
949.
本文以实验为基础,运用计算机数值解解出双电层相互作用时平面胶体表面电位ψ随距离X的分布,依据作者导出的双电层相互作用时胶体表面阴离子负吸附方程,计算出胶体表面外Hclmhotz面(OHP)处的表面电荷密度σ_δ;讨论了双电层相互作用程度(ψ_d/ψ_δ)对胶体表面电位分布及其表面电荷密度的影响。 相似文献
950.
Zhong Xue Yang Yan Jun Wu Feng Zhu YaFei Zhang 《Physica E: Low-dimensional Systems and Nanostructures》2005,25(4):395-398
A novel one-dimensional helical nanocable structure has been synthesized through the reaction of carbon fiber with SiO vapor. The crystalline SiC core typically has diameters of 10–20 nm with a helical periodicity of 30–40 nm and is covered by a uniform layer of 10–20 nm thick amorphous SiO2. A growth mechanism is proposed on the basis of difference in the growth rate between crystalline SiC core and amorphous SiO2 shell. 相似文献