全文获取类型
收费全文 | 2487篇 |
免费 | 148篇 |
国内免费 | 16篇 |
专业分类
化学 | 1951篇 |
晶体学 | 23篇 |
力学 | 83篇 |
数学 | 115篇 |
物理学 | 479篇 |
出版年
2024年 | 3篇 |
2023年 | 14篇 |
2022年 | 47篇 |
2021年 | 69篇 |
2020年 | 43篇 |
2019年 | 60篇 |
2018年 | 41篇 |
2017年 | 42篇 |
2016年 | 95篇 |
2015年 | 93篇 |
2014年 | 118篇 |
2013年 | 159篇 |
2012年 | 270篇 |
2011年 | 255篇 |
2010年 | 152篇 |
2009年 | 136篇 |
2008年 | 189篇 |
2007年 | 157篇 |
2006年 | 146篇 |
2005年 | 124篇 |
2004年 | 100篇 |
2003年 | 93篇 |
2002年 | 87篇 |
2001年 | 36篇 |
2000年 | 21篇 |
1999年 | 21篇 |
1998年 | 8篇 |
1997年 | 8篇 |
1996年 | 5篇 |
1995年 | 10篇 |
1994年 | 4篇 |
1993年 | 9篇 |
1992年 | 3篇 |
1991年 | 6篇 |
1990年 | 3篇 |
1989年 | 4篇 |
1987年 | 2篇 |
1986年 | 4篇 |
1985年 | 3篇 |
1984年 | 2篇 |
1983年 | 3篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1979年 | 1篇 |
1976年 | 1篇 |
1969年 | 1篇 |
排序方式: 共有2651条查询结果,搜索用时 991 毫秒
131.
Thermoresponsive hybrid nanocellulose hydrogels were prepared from a mixture of oxidized nanocellulose and elastin-like polypeptide (ELP). Positively charged ELP was used as a polymeric crosslinker for conjugation with negatively charged nanocellulose. Hydrogel formation was triggered by a simple increase in temperature, and the hydrogel was reversibly returned to the liquid phase by decreasing temperature. Surface potential measurement confirmed the electrostatic properties of oxidized nanocellulose and ELP molecules. The surface morphology of hydrogels was observed by atomic force microscopy and field emission-scanning electron microscopy. Conformational changes in the ELP/nanocellulose hybrid were characterized by circular dichroism. The ELP/nanocellulose hybrid hydrogel was noncytotoxic and suitable for encapsulating cells, indicating its potential for biomedical applications. 相似文献
132.
Stabilization of Catalytically Active Cu+ Surface Sites on Titanium–Copper Mixed‐Oxide Films 下载免费PDF全文
Dr. Ashleigh E. Baber Dr. Xiaofang Yang Dr. Hyun You Kim Dr. Kumudu Mudiyanselage Markus Soldemo Dr. Jonas Weissenrieder Dr. Sanjaya D. Senanayake Dr. Abdullah Al‐Mahboob Dr. Jerzy T. Sadowski Dr. Jaime Evans Dr. José A. Rodriguez Dr. Ping Liu Dr. Friedrich M. Hoffmann Dr. Jingguang G. Chen Dr. Darío J. Stacchiola 《Angewandte Chemie (International ed. in English)》2014,53(21):5336-5340
The oxidation of CO is the archetypal heterogeneous catalytic reaction and plays a central role in the advancement of fundamental studies, the control of automobile emissions, and industrial oxidation reactions. Copper‐based catalysts were the first catalysts that were reported to enable the oxidation of CO at room temperature, but a lack of stability at the elevated reaction temperatures that are used in automobile catalytic converters, in particular the loss of the most reactive Cu+ cations, leads to their deactivation. Using a combined experimental and theoretical approach, it is shown how the incorporation of titanium cations in a Cu2O film leads to the formation of a stable mixed‐metal oxide with a Cu+ terminated surface that is highly active for CO oxidation. 相似文献
133.
Tae Woo Kim Eun‐Jin Oh Ah‐Young Jee Seung Tae Lim Dae Hoon Park Minyung Lee Sang‐Hoon Hyun Prof. Jin‐Ho Choy Prof. Seong‐Ju Hwang Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(41):10752-10761
A colloidal suspension of exfoliated, layered cobalt oxide nanosheets has been synthesized through the intercalation of quaternary tetramethylammonium ions into protonated lithium cobalt oxide. According to atomic force microscopy, exfoliated nanosheets of layered cobalt oxide show a plateau‐like height profile with nanometer‐level height, underscoring the formation of unilamellar 2D nanosheets. The exfoliation of layered cobalt oxide was cross‐confirmed by X‐ray diffraction, UV/Vis spectroscopy, and transmission electron microscopy. The maintenance of the hexagonal in‐plane structure of the cobalt oxide lattice after the exfoliation process was evidenced by selected‐area electron diffraction and Co K‐edge X‐ray absorption near‐edge structure analysis. The zeta‐potential measurements clearly demonstrated the negative surface charge of cobalt oxide nanosheets. Adopting the nanosheets of layered cobalt oxide as a precursor, we were able to prepare the monodisperse CoO nanocrystals with a particle size of ≈10 nm as well as the heterolayered film composed of cobalt oxide monolayer and polycation. 相似文献
134.
An ambient drying process (1 atm, 270 °C) has been developed in order to synthesize window glazing coated with silica aerogel films. The aerogel film could be manufactured by this process of wet gel films obtained via a dip-/spin-coating of the silica sol on a glass slide. Before drying, the isoproponol solvent in wet gels was exchanged with n-heptane to minimize the drying shrinkage. The thickness, refractive index, and porosity of silica films were 0.16–10 μm, 1.08–1.09, and 80–84%, respectively. The transmittance of window glazing was over 90% and we could predict that the optimal thermal conductivity (0.2 W/(m K)) of the window glazing would be obtained at the aerogel thickness of 100 μm (0.016 W/(m K)). 相似文献
135.
Ye Seul Kim Jung Won Yoon Dasol Kim Seunghak Choi Hyoung Kyu Kim Jae Boum Youm Jin Han Soon Chul Heo Sung-Ae Hyun Jung-Wook Seo Deok-Ho Kim Jae Ho Kim 《Experimental & molecular medicine》2022,54(4):493
Human embryonic stem cell-derived cardiomyocytes (hESC-CMs) have been reported to exhibit immature embryonic or fetal cardiomyocyte-like phenotypes. To enhance the maturation of hESC-CMs, we identified a natural steroidal alkaloid, tomatidine, as a new substance that stimulates the maturation of hESC-CMs. Treatment of human embryonic stem cells with tomatidine during cardiomyocyte differentiation stimulated the expression of several cardiomyocyte-specific markers and increased the density of T-tubules. Furthermore, tomatidine treatment augmented the number and size of mitochondria and enhanced the formation of mitochondrial lamellar cristae. Tomatidine treatment stimulated mitochondrial functions, including mitochondrial membrane potential, oxidative phosphorylation, and ATP production, in hESC-CMs. Tomatidine-treated hESC-CMs were more sensitive to doxorubicin-induced cardiotoxicity than the control cells. In conclusion, the present study suggests that tomatidine promotes the differentiation of stem cells to adult cardiomyocytes by accelerating mitochondrial biogenesis and maturation and that tomatidine-treated mature hESC-CMs can be used for cardiotoxicity screening and cardiac disease modeling.Subject terms: Heart failure, Embryonic stem cells, Stem-cell differentiation 相似文献
136.
Adachi I Aihara H Arinstein K Asner DM Aushev T Aziz T Bakich AM Barberio E Belous K Bhardwaj V Bhuyan B Bondar A Bračko M Brodzicka J Browder TE Chang P Chen A Chen P Cheon BG Chilikin K Chistov R Cho IS Cho K Choi Y Dalseno J Danilov M Drásal Z Drutskoy A Eidelman S Epifanov D Esen S Fast JE Feindt M Gaur V Gabyshev N Garmash A Goh YM Golob B Hara T Hayasaka K Hayashii H Hoshi Y Hou WS Hsiung YB Hyun HJ Iijima T Ishikawa A Iwabuchi M Iwasaki Y Jaegle I Julius T Kang JH Katayama N Kawasaki T 《Physical review letters》2012,108(3):032001
We report the first observations of the spin-singlet bottomonium states h(b)(1P) and h(b)(2P). The states are produced in the reaction e(+)e(-)→h(b)(nP)π(+)π(-) using a 121.4 fb(-1) data sample collected at energies near the Υ(5S) resonance with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider. We determine M[h(b)(1P)]=(9898.2(-1.0-1.1)(+1.1+1.0)) MeV/c(2) and M[h(b)(2P)]=(10,259.8±0.6(-1.0)(+1.4)) MeV/c(2), which correspond to P-wave hyperfine splittings ΔM(HF)=(+1.7±1.5) and (+0.5(-1.2)(+1.6)) MeV/c(2), respectively. The significances of the h(b)(1P) and h(b)(2P) are 5.5σ and 11.2σ, respectively. We find that the production of the h(b)(1P) and h(b)(2P) is not suppressed relative to the production of the Υ(1S), Υ(2S), and Υ(3S). 相似文献
137.
Jooung-Hyun Jo Hyun-Cheol Ko Byeong-Woo Kim Hyun Park In-won Lee Ho-Hwan Chun 《Composite Interfaces》2016,23(8):797-805
AbstractMarine fouling can be a serious problem in the shipping industry, since it increases the surface roughness of the hull and hence its frictional resistance to its movement through water. Antifouling paint can be defined as preventing the attachment of marine organisms onto surfaces. However, the most commonly used antifouling coating which is the tributyltin-based self-polishing copolymer causes the severe pollution of marine environment. Ammonium salt-based paints include tertiary amines as biocides which have effective biocidal and biodegradable properties without accumulation in the sea environment. However, ammonium salt-based coatings were too sensitive to seawater and became swollen. In this study, polyurethane-acrylic copolymers were synthesized by radical polymerization. These hybrid materials were found to form core–shell structures in aqueous media. Synthesis and properties of copolymers were investigated by Fourier transform-infrared spectrometer, proton-nuclear magnetic resonance, transmission electron microscopy, and dynamic light scattering. The polishing rate of self-polishing copolymer was determined from the reduction in dry film thickness after artificial seawater immersion under a dynamic condition. 相似文献
138.
139.
140.