全文获取类型
收费全文 | 21864篇 |
免费 | 2146篇 |
国内免费 | 1639篇 |
专业分类
化学 | 11786篇 |
晶体学 | 225篇 |
力学 | 1021篇 |
综合类 | 224篇 |
数学 | 3101篇 |
物理学 | 9292篇 |
出版年
2023年 | 190篇 |
2022年 | 320篇 |
2021年 | 549篇 |
2020年 | 553篇 |
2019年 | 516篇 |
2018年 | 492篇 |
2017年 | 605篇 |
2016年 | 664篇 |
2015年 | 631篇 |
2014年 | 840篇 |
2013年 | 1599篇 |
2012年 | 1183篇 |
2011年 | 1034篇 |
2010年 | 877篇 |
2009年 | 1263篇 |
2008年 | 1307篇 |
2007年 | 1514篇 |
2006年 | 1259篇 |
2005年 | 1008篇 |
2004年 | 926篇 |
2003年 | 881篇 |
2002年 | 801篇 |
2001年 | 694篇 |
2000年 | 609篇 |
1999年 | 573篇 |
1998年 | 519篇 |
1997年 | 404篇 |
1996年 | 321篇 |
1995年 | 313篇 |
1994年 | 289篇 |
1993年 | 277篇 |
1992年 | 330篇 |
1991年 | 218篇 |
1990年 | 160篇 |
1989年 | 133篇 |
1988年 | 117篇 |
1987年 | 112篇 |
1986年 | 95篇 |
1985年 | 82篇 |
1984年 | 96篇 |
1983年 | 48篇 |
1982年 | 106篇 |
1981年 | 177篇 |
1980年 | 189篇 |
1979年 | 183篇 |
1978年 | 169篇 |
1977年 | 107篇 |
1976年 | 108篇 |
1973年 | 80篇 |
1972年 | 37篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
1.
2.
3.
Jie Pan Yan Bao Hao Wang Fucong Lyu Lu Liu Chong Wang Xinxue Tang Jian Lu Yang Yang Li 《Particle & Particle Systems Characterization》2021,38(10):2100094
The high-entropy materials have raised much attention in recent years due to their extraordinary performances in mechanical, catalysis, energy storage fields. Herein, a new type of high-entropy hydroxides (e.g., NiFeCoMnAl(OH)x) that are amorphous and capable of broad solar absorption is reported. A facile one-pot co-precipitation method is employed to synthesize these amorphous high-entropy hydroxides (a-HEHOs) under ambient conditions. The a-HEHOs thus obtained display widely tunable bandgap (e.g., from 2.6 to 1.1 eV) due to their high-entropy and amorphous characteristics, enabling efficient light absorbance and photothermal conversion in the solar regime. Further solar water evaporation measurements show that the a-HEHOs delivered a considerable energy conversion efficiency of 55%, comparable to black titanium oxides that are synthesized using more complex and expensive methods. 相似文献
4.
深挖高职院校公选课“生活中的化学”的育人元素,精心设计教学内容,运用课堂主题辩论、趣味生活实验的设计与展示、探秘生活中的化学等理论知识传授与课内外实践相结合的教学方式,实现全过程育人,充分展现了公选课在立德树人方面的价值。 相似文献
5.
Ajay Gupta Fillip Kumar Sarkar Rajib Sarkar Ramen Jamatia Chang Yeon Lee Gajendra Gupta Amarta Kumar Pal 《应用有机金属化学》2020,34(9):e5782
Magnetically retrieval CuFe2O4@MIL-101(Cr) metal–organic framework was successfully prepared from easily available starting materials and characterized using various spectroscopic and analytical techniques such as powder X-ray diffraction, scanning electron microscopy, energy dispersive X-ray, transmission electron microscopy, elemental mapping, Fourier transform infrared spectroscopy, thermogravimetric analysis, X-ray photoelectron spectroscopy, Brunauer–Emmett–Teller, vibrating sample magnetometer, and inductively coupled plasma optical emission spectroscopy. The catalyst was then used in the synthesis of benzodiazepines containing a triazole moiety in water. The advantages of this protocol include high yields, reusability of the catalyst, and gram-scale synthesis. 相似文献
6.
Chen Zhao Zifeng Chen Wei Wang Peixun Xiong Benfang Li Mengjie Li Dr. Jixing Yang Prof. Yunhua Xu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(29):12090-12096
Organic cathode materials have attracted extensive attention because of their diverse structures, facile synthesis, and environmental friendliness. However, they often suffer from insufficient cycling stability caused by the dissolution problem, poor rate performance, and low voltages. An in situ electropolymerization method was developed to stabilize and enhance organic cathodes for lithium batteries. 4,4′,4′′-Tris(carbazol-9-yl)-triphenylamine (TCTA) was employed because carbazole groups can be polymerized under an electric field and they may serve as high-voltage redox-active centers. The electropolymerized TCTA electrodes demonstrated excellent electrochemical performance with a high discharge voltage of 3.95 V, ultrafast rate capability of 20 A g−1, and a long cycle life of 5000 cycles. Our findings provide a new strategy to address the dissolution issue and they explore the molecular design of organic electrode materials for use in rechargeable batteries. 相似文献
7.
Dr. Wenyan Hao Yuchen Sha Dr. Yi Deng Yi Luo Li Zeng Shan Tang Dr. Yue Weng Prof. Dr. Chien-Wei Chiang Prof. Dr. Aiwen Lei 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(19):4931-4934
An in situ generated oxidation species of nickel quinolinylpropioamide intermediate was produced. Characterization by X-ray absorption near edge structure (XANES) and EPR provides complementary insights into this oxidized nickel species. With aliphatic amides and isocyanides as substrates, a nickel-catalyzed facile synthesis of structurally diverse five-membered lactams could be achieved. 相似文献
8.
We will focus on the existence of nontrivial solutions to the following Hamiltonian elliptic system where are numbers belonging to the interval [0, 2), V is a continuous potential bounded below on by a positive constant and the functions f and g possess exponential growth range established by Trudinger–Moser inequalities in Lorentz–Sobolev spaces. The proof involves linking theorem and a finite‐dimensional approximation. 相似文献
9.
Bilender P. Allahverdiev 《Mathematical Methods in the Applied Sciences》2019,42(1):229-236
In this study, maximal dissipative second‐order dynamic operators on semi‐infinite time scale are studied in the Hilbert space , that the extensions of a minimal symmetric operator in limit‐point case. We construct a self‐adjoint dilation of the dissipative operator together with its incoming and outgoing spectral representations so that we can determine the scattering function of the dilation as stated in the scheme of Lax‐Phillips. Moreover, we construct a functional model of the dissipative operator and identify its characteristic function in terms of the Weyl‐Titchmarsh function of a self‐adjoint second‐order dynamic operator. Finally, we prove the theorems on completeness of the system of root functions of the dissipative and accumulative dynamic operators. 相似文献
10.
Awatif Alqahtani Mohamed Jleli Bessem Samet 《Mathematical Methods in the Applied Sciences》2019,42(3):861-870
In this paper, some nonlocal in time differential inequalities of Sobolev type are considered. Using the nonlinear capacity method, sufficient conditions for the nonexistence of nontrivial global classical solutions are provided. 相似文献