全文获取类型
收费全文 | 282168篇 |
免费 | 4454篇 |
国内免费 | 2706篇 |
专业分类
化学 | 131480篇 |
晶体学 | 4521篇 |
力学 | 14841篇 |
综合类 | 153篇 |
数学 | 45452篇 |
物理学 | 92881篇 |
出版年
2021年 | 1762篇 |
2020年 | 2016篇 |
2019年 | 2255篇 |
2018年 | 11184篇 |
2017年 | 12070篇 |
2016年 | 7882篇 |
2015年 | 3501篇 |
2014年 | 4152篇 |
2013年 | 8905篇 |
2012年 | 11292篇 |
2011年 | 20431篇 |
2010年 | 13023篇 |
2009年 | 13106篇 |
2008年 | 17928篇 |
2007年 | 21184篇 |
2006年 | 7071篇 |
2005年 | 12732篇 |
2004年 | 8985篇 |
2003年 | 8380篇 |
2002年 | 6340篇 |
2001年 | 5752篇 |
2000年 | 4490篇 |
1999年 | 3332篇 |
1998年 | 2784篇 |
1997年 | 2628篇 |
1996年 | 2618篇 |
1995年 | 2396篇 |
1994年 | 2330篇 |
1993年 | 2238篇 |
1992年 | 2477篇 |
1991年 | 2420篇 |
1990年 | 2351篇 |
1989年 | 2279篇 |
1988年 | 2279篇 |
1987年 | 2250篇 |
1986年 | 2136篇 |
1985年 | 2767篇 |
1984年 | 2815篇 |
1983年 | 2494篇 |
1982年 | 2605篇 |
1981年 | 2406篇 |
1980年 | 2381篇 |
1979年 | 2540篇 |
1978年 | 2578篇 |
1977年 | 2419篇 |
1976年 | 2509篇 |
1975年 | 2414篇 |
1974年 | 2379篇 |
1973年 | 2594篇 |
1972年 | 1665篇 |
排序方式: 共有10000条查询结果,搜索用时 203 毫秒
101.
102.
Dr. Feifan Wang Jie Tian Dr. Mengzhu Li Dr. Weizhen Li Dr. Lifang Chen Xiaozhi Liu Dr. Jian Li Aidaer Muhetaer Prof. Dr. Qi Li Prof. Dr. Yuan Wang Prof. Dr. Lin Gu Prof. Dr. Ding Ma Prof. Dr. Dongsheng Xu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(21):8280-8286
Fully utilizing solar energy for catalysis requires the integration of conversion mechanisms and therefore delicate design of catalyst structures and active species. Herein, a MOF crystal engineering method was developed to controllably synthesize a copper–ceria catalyst with well-dispersed photoactive Cu-[O]-Ce species. Using the preferential oxidation of CO as a model reaction, the catalyst showed remarkably efficient and stable photoactivated catalysis, which found practical application in feed gas treatment for fuel cell gas supply. The coexistence of photochemistry and thermochemistry effects contributes to the high efficiency. Our results demonstrate a catalyst design approach with atomic or molecular precision and a combinatorial photoactivation strategy for solar energy conversion. 相似文献
103.
104.
105.
Following a thermal reduction method, platinum nanoparticles were synthesized and stabilized by polyvinylpyrrolidone. The colloidal platinum nanoparticles were stable for more than 3 months. The micrograph analysis unveiled that the colloidal platinum nanoparticles were well dispersed with an average size of 2.53 nm. The sol–gel‐based inverse micelle strategy was applied to synthesize mesoporous iron oxide material. The colloidal platinum nanoparticles were deposited on mesoporous iron oxide through the capillary inclusion method. The small‐angle X‐ray scattering analysis indicated that the dimension of platinum nanoparticles deposited on mesoporous iron oxide (Pt‐Fe2O3) was 2.64 nm. X‐ray photoelectron spectroscopy (XPS) data showed that the binding energy on Pt‐Fe2O3 surface decreased owing to mesoporous support–nanoparticle interaction. Both colloidal and deposited platinum nanocatalysts improved the degradation of methyl orange under reduction conditions. The activation energy on the deposited platinum nanocatalyst interface (2.66 kJ mol?1) was significantly lowered compared with the one on the colloidal platinum nanocatalyst interface (40.63 ± 0.53 kJ mol?1). 相似文献
106.
107.
108.
Yimei Wang Yi Qiao Xiaomin Xu Xiaohong Ding Weiwei Li Bo Yuan Haiyan Xu 《Biomedical chromatography : BMC》2019,33(8)
A sensitive and reliable LC–MS/MS method was developed and validated for simultaneous quantification of the major components of Huangqi–Honghua extact in rat plasma, including hydroxysafflor yellow A (HSYA), astragaloside IV (ASIV), calycosin‐7‐O‐β‐d ‐glucoside (CAG), calycosin, calycosin‐3′‐O‐glucuronide (C‐3′‐G) and calycosin‐3′‐O‐sulfate (C‐3′‐S). After extraction by protein precipitation with acetonitrile and methanol from plasma, the analytes were separated on a Hypersil BDS C18 column by gradient elution with acetonitrile and 5 mM ammonium acetate. The detection was carried out on a triple quadrupole tandem mass spectrometer equipped with electrospray ionization source switched between negative and positive modes. HSYA was monitored in negative ionization mode from 0 to 4.9 min, and ASIV, CAG, calycosin, C‐3′‐G and C‐3′‐S were determined in positive ionization mode from 4.9 to 10 min. The lower limits of quantification of the analytes were 6.25 ng/mL for HSYA, 0.781 ng/mL for CAG and 1.56 ng/mL for ASIV and calycosin. The intra‐ and inter‐assay precision (RSD) values were within 13.43%, and accuracy (RE) ranged from ?8.75 to 9.92%. The validated method was then applied to the pharmacokinetic study of HSYA, ASIV, CAG, calycosin, C‐3′‐G and C‐3′‐S in rat after an oral administration of Huangqi–Honghua extract. 相似文献
109.
110.
Sh. M. Khaliullin V. D. Zhuravlev V. G. Bamburov L. V. Ermakova 《Physics of Atomic Nuclei》2015,78(12):1382-1388
Submicron CaZrO3 powder is obtained in combustion reactions (solution combustion synthesis—SCS) with glycine. It is found that SCS reduces the sintering temperature of CaZrO3 powders. The dielectric properties of calcium zirconate ceramics are studied by the electrochemical impedance method. It is shown that a ceramics of powders obtained by the SCS method has high dielectric characteristics. 相似文献