全文获取类型
收费全文 | 2273篇 |
免费 | 350篇 |
国内免费 | 217篇 |
专业分类
化学 | 1704篇 |
晶体学 | 16篇 |
力学 | 150篇 |
综合类 | 29篇 |
数学 | 184篇 |
物理学 | 757篇 |
出版年
2024年 | 9篇 |
2023年 | 53篇 |
2022年 | 66篇 |
2021年 | 91篇 |
2020年 | 102篇 |
2019年 | 94篇 |
2018年 | 78篇 |
2017年 | 55篇 |
2016年 | 109篇 |
2015年 | 114篇 |
2014年 | 106篇 |
2013年 | 148篇 |
2012年 | 190篇 |
2011年 | 204篇 |
2010年 | 122篇 |
2009年 | 112篇 |
2008年 | 156篇 |
2007年 | 137篇 |
2006年 | 121篇 |
2005年 | 127篇 |
2004年 | 73篇 |
2003年 | 56篇 |
2002年 | 59篇 |
2001年 | 51篇 |
2000年 | 51篇 |
1999年 | 47篇 |
1998年 | 38篇 |
1997年 | 35篇 |
1996年 | 30篇 |
1995年 | 29篇 |
1994年 | 31篇 |
1993年 | 22篇 |
1992年 | 18篇 |
1991年 | 28篇 |
1990年 | 18篇 |
1989年 | 8篇 |
1988年 | 9篇 |
1987年 | 9篇 |
1985年 | 5篇 |
1984年 | 3篇 |
1983年 | 8篇 |
1982年 | 2篇 |
1981年 | 2篇 |
1980年 | 5篇 |
1978年 | 1篇 |
1976年 | 2篇 |
1974年 | 1篇 |
1959年 | 1篇 |
1947年 | 1篇 |
1946年 | 1篇 |
排序方式: 共有2840条查询结果,搜索用时 31 毫秒
1.
Shilin Jiang Dr. Yalan Liu Dr. Lin Wang Prof. Zhifang Chai Prof. Wei-Qun Shi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(60):e202201145
The coordination chemistry of f-block elements (lanthanide and actinide) in molten salts has become a resounding topic in view of its great importance to the research and development (R&D) of molten salt reactors and pyroprocessing. In this Review article, a general overview of the coordination chemistry of f-block elements in molten salts is provided including past achievements and recent advances. Particular emphases are placed on the oxidation state, speciation, and solution structure of f-block metal ions in molten salts, as well as their relationships with the salt composition. Furthermore, this review briefly discusses the spectroscopic and theoretical methods that complement each other in revealing the coordination properties. 相似文献
2.
Acta Mechanica Sinica - 相似文献
3.
Ziritaxestat is a first-in-class autotoxin inhibitor. The purpose of this study was to develop a liquid chromatography/electrospray ionization tandem mass spectrometric (LC–MS/MS) method for the determination of ziritaxestat in rat plasma. The plasma sample was deproteinated using acetonitrile and then separated on an Acquity BEH C18 column with water containing 0.1% formic acid and acetonitrile as mobile phase, which was delivered at 0.4 ml/min. Ziritaxestat and the internal standard (crizotinib) were quantitatively monitored with precursor-to-product transitions of m/z 589.3 > 262.2 and m/z 450.1 > 260.2, respectively. The total running time was 2.5 min. The method showed excellent linearity over the concentration range 0.5–2000 ng/ml, with correlation coefficient >0.9987. The extraction recovery was >82.09% and the matrix effect was not significant. Inter- and intra-day precisions (RSD) were <11.20% and accuracies were in the range of −8.50–7.45%. Ziritaxestat was demonstrated to be stable in rat plasma under the tested conditions. The validated LC–MS/MS method was successfully applied to study the pharmacokinetic profiles of ziritaxestat in rat plasma after intravenous and oral administration. Pharmacokinetic results demonstrated that ziritaxestat displayed a short half-life (~3 h) and low bioavailability (20.52%). 相似文献
4.
本文给出了混合型多项式Hammerstein积分方程正解的迭代求法,并将所得结果应用到二阶非线性常微分方程的边值问题 相似文献
5.
This paper presents a multiobjective hybrid metaheuristic approach for an intelligent spatial zoning model in order to draw territory line for geographical or spatial zone for the purpose of space control. The model employs a Geographic Information System (GIS) and uses multiobjective combinatorial optimization techniques as its components. The proposed hybrid metaheuristic consists of the symbiosis between tabu search and scatter search method and it is used heuristically to generate non-dominated alternatives. The approach works with a set of current solution, which through manipulation of weights are optimized towards the non-dominated frontier while at the same time, seek to disperse over the frontier by a strategic oscillation concept. The general procedure and its algorithms are given as well as its implementation in the GIS environment. The computation has resulted in tremendous improvements in spatial zoning. 相似文献
6.
Banach空间中一类非线性算子Ishikawa迭代序列收敛定理 总被引:7,自引:1,他引:6
柴国庆 《数学物理学报(A辑)》1998,18(4):459-466
在一般的Banach空间中,研究了Ishikawa迭代序列收敛问题,去掉了通常文献中关于空间X的一致光滑或S-一致光滑的严格要求,此外,还去掉或减弱了其它某些条件。因而本质地改进了近期文献的一系列相应定理。 相似文献
7.
Study on the in—plane electrical resistivity and thermoelectric power in single crystals of La2—xBaxCuO4
下载免费PDF全文
![点击此处可从《中国物理》网站下载免费的PDF全文](/ch/ext_images/free.gif)
The in-plane electrical resistivity and thermoelectric power have been measured on single crystals of La2-xBaxCuO4 at around x=0.125. The room temperature resistivity and thermopower have their maximum values at x=0.125, indicating that the carrier concentration is the minimum and the carriers are most strongly localized at x=0.125. The observed semiconductor-like behaviour can be well described by the weak-localized quasi-two-dimensional state. The steep rise in electric resistivity of the sample at x=0.125 below 70K is attributed to the formation of static stripe-order of holes and spins, which are pinned by the low-temperature tetragonal (LTT) structure, as discovered in La1.48Nd0.4Sr0.12CuO4. The temperature dependence of electric resistivity below 70K is still well described by the formula ρ∝ lnT. A definite change in the slope of thermopower is observed at the low-temperature orthorhombic-LTT structural phase transition temperature. The origin of the 1/8 anomaly is discussed in the text. 相似文献
8.
Qingfa Wang Li Wang Yaquan Wang Fei He Zhenhua Li Zhentao Mi 《Reaction Kinetics and Catalysis Letters》2004,81(2):297-304
Deactivated palladium catalysts in the hydrogenation of anthraquinione were regenerated with ethanol, nitric acid, hydrogen
peroxide, boiling water and steam, respectively. The deactivated and regenerated catalysts were characterized by XPS, ICP,
TG, FTIR, TPD, XRD, etc., and studied in the hydrogenation of anthraquinone. The results showed that the main cause of catalyst deactivation is the
coverage of the active component by deposits. The treatments by hydrogen peroxide and boiling water can effectively regenerate
the deactivated catalysts.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
9.
10.
自由电子激光振荡器的二维数值模拟 总被引:2,自引:2,他引:0
在柱二维坐标系中,用数值计算方法求解了摇摆器内电子模拟方程组、光场方程组和无源区(不含摇摆器区)经非自适应方法变换后的无源旁轴波动方程并设计了相应的程序R_2D。用该程序计算的数值结果表明,在有源条件下二维数值模拟结果与高斯光束近似下的数值模拟结果符合较好;取完全相同的计算条件R-2D程序与洛斯阿拉莫斯实验室(LANL)的FELEX程序的计算结果符合较好;初步认为LANL实验数据的物理图象合理,数值结果基本可信;最后给出北京自由电子激光器(BFEL)的一些物理数据。 相似文献