全文获取类型
收费全文 | 251338篇 |
免费 | 4159篇 |
国内免费 | 1353篇 |
专业分类
化学 | 138419篇 |
晶体学 | 2789篇 |
力学 | 9728篇 |
综合类 | 63篇 |
数学 | 30293篇 |
物理学 | 75558篇 |
出版年
2020年 | 2167篇 |
2019年 | 2216篇 |
2018年 | 2916篇 |
2017年 | 2974篇 |
2016年 | 4567篇 |
2015年 | 3138篇 |
2014年 | 4344篇 |
2013年 | 10593篇 |
2012年 | 9228篇 |
2011年 | 11099篇 |
2010年 | 7747篇 |
2009年 | 7357篇 |
2008年 | 10369篇 |
2007年 | 10375篇 |
2006年 | 9794篇 |
2005年 | 8961篇 |
2004年 | 7918篇 |
2003年 | 6845篇 |
2002年 | 6318篇 |
2001年 | 7193篇 |
2000年 | 5360篇 |
1999年 | 3788篇 |
1998年 | 3146篇 |
1997年 | 3167篇 |
1996年 | 3243篇 |
1995年 | 2989篇 |
1994年 | 3111篇 |
1993年 | 2965篇 |
1992年 | 3256篇 |
1991年 | 3170篇 |
1990年 | 2967篇 |
1989年 | 2857篇 |
1988年 | 2799篇 |
1987年 | 2751篇 |
1986年 | 2730篇 |
1985年 | 3696篇 |
1984年 | 3728篇 |
1983年 | 3119篇 |
1982年 | 3385篇 |
1981年 | 3141篇 |
1980年 | 2934篇 |
1979年 | 3114篇 |
1978年 | 3312篇 |
1977年 | 3344篇 |
1976年 | 3345篇 |
1975年 | 3090篇 |
1974年 | 3182篇 |
1973年 | 3191篇 |
1972年 | 2441篇 |
1971年 | 1977篇 |
排序方式: 共有10000条查询结果,搜索用时 239 毫秒
91.
Cycloparaphenylene (CPP) shows modulated photophysical and electronic properties due to its strained structure and radially oriented π-electron system. Incorporation of CPP into metal-organic frameworks (MOFs) could transfer its extensive properties in solution to porous solids. Moreover, with the unique arrangement of the macrocycles and their interactions with the framework, emerging characteristics are anticipated. As an example of “robust dynamics”, we synthesized the first MOF structure (FDM-1001) with CPP precisely anchored to the ordered framework by employing a [8]CPP-containing linear dicarboxylate linker. Metric relationship between the dynamic macrocycles and the robust backbone creates ideal π-π interactions between them, which leads to an essentially directional arrangement of [8]CPP in the three-dimensional space. Furthermore, the MOF with [8]CPP could be successfully oxidized to generate an infinite array of radicals that show enhanced air stability compared to its molecular analogue. 相似文献
92.
Gazizov M. B. Ismagilov R. K. Ivanova S. Yu. Karimova R. F. Pistsova A. L. Khairullin R. A. Gazizova N. N. Shaikhutdinova L. R. Gubaidullin A. T. Gnezdilov O. I. 《Russian Chemical Bulletin》2022,71(3):457-463
Russian Chemical Bulletin - Diethylphosphinylmethanehydrazide, the first representative of the phosphorylated formic acid hydrazides with three P—C bonds was obtained, which can exhibit... 相似文献
93.
Ermolayev A. V. Tulegenova A. T. Lisitsyna L. A. Korzhneva T. G. Lisitsyn V. M. 《Russian Physics Journal》2022,64(9):1692-1696
Russian Physics Journal - It is shown that the morphology of the YAG:Ce ceramic samples synthesized in the field of high-energy electron flux depends on the degree of compaction of the initial... 相似文献
94.
Theoretical and Mathematical Physics - The quasipolynomial (QP) formalism and the Painlevé property constitute two distinct approaches for studying the integrability of systems of ordinary... 相似文献
95.
Annals of Operations Research - The vehicle routing problem is a traditional combinatorial problem with practical relevance for a wide range of industries. In the literature, several specificities... 相似文献
96.
Gürbüzbalaban Mert Ruszczyński Andrzej Zhu Landi 《Journal of Optimization Theory and Applications》2022,194(3):1014-1041
Journal of Optimization Theory and Applications - We consider a distributionally robust formulation of stochastic optimization problems arising in statistical learning, where robustness is with... 相似文献
97.
Mathematical Programming - A framework is proposed for solving general convex quadratic programs (CQPs) from an infeasible starting point by invoking an existing feasible-start algorithm tailored... 相似文献
98.
Kravets L. I. Yarmolenko M. A. Rogachev A. V. Gainutdinov R. V. Altynov V. A. Lizunov N. E. 《Colloid Journal》2022,84(4):427-444
Colloid Journal - Different methods have been considered for the formation of coatings on the surface of a hydrophilic poly(ethylene terephthalate) track-etched membrane with the help of... 相似文献
99.
Optics and Spectroscopy - Heterogeneity of aqueous solutions of polythymidylic acid (poly-T) at room temperature is established by luminescence and absorption spectroscopy. It is found that there... 相似文献
100.
Corinne Rondeau-Mouro Mireille Cambert Laurent Blondel Yves Diascorn Léo Mbaya Nor Nadiah Binti Ahmad Nazari Sarah Helary Tiphaine Lucas 《Magnetic resonance in chemistry : MRC》2022,60(7):678-691
A temperature control unit was implemented to vary the temperature of samples studied on a commercial Mobile Universal Surface Explorer nuclear magnetic resonance (MOUSE-NMR) apparatus. The device was miniaturized to fit the maximum MOUSE sampling depth (25 mm). It was constituted by a sample holder sandwiched between two heat exchangers placed below and above the sample. Air was chosen as the fluid to control the temperature at the bottom of the sample, at the interface between the NMR probe and the sample holder, in order to gain space. The upper surface of the sample was regulated by the circulation of water inside a second heat exchanger placed above the sample holder. The feasibility of using such a device was demonstrated first on pure water and then on several samples of bread dough with different water contents. For this, T1 relaxation times were measured at various temperatures and depths and were then compared with those acquired with a conventional compact closed-magnet spectrometer. Discussion of results was based on biochemical transformations in bread dough (starch gelatinization and gluten heat denaturation). It was demonstrated that, within a certain water level range, and because of the low magnetic field strength of the MOUSE, a linear relationship could be established between T1 relaxation times and the local temperature in the dough sample. 相似文献