全文获取类型
收费全文 | 40465篇 |
免费 | 6541篇 |
国内免费 | 6513篇 |
专业分类
化学 | 31873篇 |
晶体学 | 681篇 |
力学 | 1859篇 |
综合类 | 486篇 |
数学 | 4604篇 |
物理学 | 14016篇 |
出版年
2024年 | 83篇 |
2023年 | 717篇 |
2022年 | 1015篇 |
2021年 | 1373篇 |
2020年 | 1609篇 |
2019年 | 1676篇 |
2018年 | 1351篇 |
2017年 | 1374篇 |
2016年 | 1925篇 |
2015年 | 2058篇 |
2014年 | 2583篇 |
2013年 | 3256篇 |
2012年 | 3843篇 |
2011年 | 3960篇 |
2010年 | 2954篇 |
2009年 | 2695篇 |
2008年 | 3034篇 |
2007年 | 2712篇 |
2006年 | 2526篇 |
2005年 | 2035篇 |
2004年 | 1534篇 |
2003年 | 1265篇 |
2002年 | 1404篇 |
2001年 | 1171篇 |
2000年 | 829篇 |
1999年 | 744篇 |
1998年 | 571篇 |
1997年 | 464篇 |
1996年 | 442篇 |
1995年 | 378篇 |
1994年 | 322篇 |
1993年 | 298篇 |
1992年 | 232篇 |
1991年 | 226篇 |
1990年 | 142篇 |
1989年 | 167篇 |
1988年 | 97篇 |
1987年 | 90篇 |
1986年 | 70篇 |
1985年 | 79篇 |
1984年 | 59篇 |
1983年 | 34篇 |
1982年 | 29篇 |
1981年 | 22篇 |
1980年 | 20篇 |
1979年 | 6篇 |
1978年 | 8篇 |
1977年 | 7篇 |
1976年 | 8篇 |
1957年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Liu Wenbin Huang Yiwei Huang Guolin Fan Lijiao Xie Yuming Shi Jeffery 《Journal of Radioanalytical and Nuclear Chemistry》2022,331(5):2055-2068
Journal of Radioanalytical and Nuclear Chemistry - Eco-friendly and low-cost composite, amidoxime-functionalized microcrystalline cellulose/mesoporous silica (MCC/MS-AO), were synthesized by... 相似文献
2.
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
3.
Dr. Zaifa Shi Dr. Yihuang Jiang Dr. Jingxiong Yu Prof. Shanjun Chen Prof. Jun Chen Prof. Zichao Tang Prof. Lansun Zheng 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(8):e202103546
At present, the reactivity of cyclic alkanes is estimated by comparison with acyclic hydrocarbons. Due to the difference in the structure of cycloalkanes and acycloalkanes, the thermodynamic data obtained by analogy are not applicable. In this study, a molecular beam sampling vacuum ultraviolet photoionization time-of-flight mass spectrometer (MB-VUV-PI-TOFMS) was applied to study the low-temperature oxidation of cyclopentane (CPT) at a total pressure range from 1–3 atm and low-temperature range between 500 and 800 K. Low-temperature reaction products including cyclic olefins, cyclic ethers, and highly oxygenated intermediates (e. g., ketohydroperoxide KHP, keto-dihydroperoxide KDHP, olefinic hydroperoxides OHP and ketone structure products) were observed. Further investigation of the oxidation of CPT – electronic structure calculations – were carried out at the UCCSD(T)-F12a/aug-cc-pVDZ//B3LYP/6-31+ G(d,p) level to explore the reactivity of O2 molecules adding sequentially to cyclopentyl radicals. Experimental and theoretical observations showed that the dominant product channel in the reaction of CPT radicals with O2 is HO2 elimination yielding cyclopentene. The pathways of second and third O2 addition – the dissociation of hydroperoxide – were further confirmed. The results of this study will develop the low-temperature oxidation mechanism of CPT, which can be used for future research on accurately simulating the combustion process of CPT. 相似文献
4.
Tian Jie Yang Weifeng Chen Min Zheng Minfang Chen Ding Qiu Yusheng 《Journal of Radioanalytical and Nuclear Chemistry》2022,331(2):1039-1049
Journal of Radioanalytical and Nuclear Chemistry - This study presents a time-efficient method of analysing 210Pb, 210Bi, and 210Po in natural waters. The optimum pH (1.00), temperature... 相似文献
5.
A numerical model was developed and validated to investigate the fluid–structure interactions between fully developed pipe flow and core–shell-structured microcapsule in a microchannel. Different flow rates and microcapsule shell thicknesses were considered. A sixth-order rotational symmetric distribution of von Mises stress over the microcapsule shell can be observed on the microcapsule with a thinner shell configuration, especially at higher flow rate conditions. It is also observed that when being carried along in a fully developed pipe flow, the microcapsule with a thinner shell tends to accumulate stress at a higher rate compared to that with a thicker shell. In general, for the same microcapsule configuration, higher flow velocity would induce a higher stress level over the microcapsule shell. The deformation gradient was used to capture the microcapsule's deformation in the present study. The effect of Young's modulus on the microcapsule shell on the microcapsule deformation was investigated as well. Our findings will shed light on the understanding of the stability of core–shell-structured microcapsule when subjected to flow-induced shear stress in a microfluidic system, enabling a more exquisite control over the breakup dynamics of drug-loaded microcapsule for biomedical applications. 相似文献
6.
Li Y. Shi W. H. Dong L. M. Xu S. X. Huang H. J. Yin J. R. 《Journal of Applied Spectroscopy》2022,89(3):534-541
Journal of Applied Spectroscopy - Sr3B2O6:Dy3+, Eu3+ single-matrix white-light-emitting materials are prepared using the high-temperature solid-state method. The microstructure, emission spectrum,... 相似文献
7.
We study the Leibniz n-algebra Un(∑),whose multiplication is defined viathe bracket of a Leibniz algebra ∑ as[x1,...,xn]=[x1,[...,[xn-2,[xn-1,xn]]...]].Weshow that Un(∑) is simple if and only if ∑ is a simple Lie algebra.An analog of Levi'stheorem for Leibniz algebras in Un(Lb) is established and it is proven that the Leibnizn-kernel of Un(Σ) for any semisimple Leibniz algebra Σ is the n-algebra Un(Σ). 相似文献
8.
Journal of Visualization - The increasing availability of spatiotemporal data provides unprecedented opportunities for understanding the structure of an urban area in terms of people’s... 相似文献
9.
International Journal of Theoretical Physics - The Majorana representation, which provides an intuitive way to represent the quantum state by stars on the Bloch sphere, has drawn considerable... 相似文献
10.
The chiral phase transition and equation of state are studied within a novel self-consistent mean-field approximation of the two-flavor Nambu-Jona-Lasinio model. In this newly developed model, modifications to the chemical μ and chiral chemical \begin{document}$\mu_5$\end{document} ![]()
![]()
potentials are naturally included by introducing vector and axial-vector channels from Fierz-transformed Lagrangian to the standard Lagrangian. In the proper-time scheme, the chiral phase transition is a crossover in the \begin{document}$T-\mu$\end{document} ![]()
![]()
plane. However, when \begin{document}$\mu_5$\end{document} ![]()
![]()
is incorporated, our study demonstrates that a first order phase transition may emerge. Furthermore, the chiral imbalance will soften the equation of state of quark matter. The mass-radius relationship and tidal deformability of quark stars are calculated. The maximum mass and radius decrease as \begin{document}$\mu_5$\end{document} ![]()
![]()
increases. Our study also indicates that the vector and axial-vector channels exhibit an opposite influence on the equation of state. 相似文献