全文获取类型
收费全文 | 23235篇 |
免费 | 3529篇 |
国内免费 | 3280篇 |
专业分类
化学 | 12331篇 |
晶体学 | 296篇 |
力学 | 1940篇 |
综合类 | 289篇 |
数学 | 7582篇 |
物理学 | 7606篇 |
出版年
2024年 | 29篇 |
2023年 | 269篇 |
2022年 | 478篇 |
2021年 | 630篇 |
2020年 | 804篇 |
2019年 | 765篇 |
2018年 | 755篇 |
2017年 | 847篇 |
2016年 | 926篇 |
2015年 | 824篇 |
2014年 | 1223篇 |
2013年 | 2437篇 |
2012年 | 1308篇 |
2011年 | 1389篇 |
2010年 | 1171篇 |
2009年 | 1376篇 |
2008年 | 1485篇 |
2007年 | 1692篇 |
2006年 | 1403篇 |
2005年 | 1247篇 |
2004年 | 1120篇 |
2003年 | 1092篇 |
2002年 | 896篇 |
2001年 | 795篇 |
2000年 | 777篇 |
1999年 | 667篇 |
1998年 | 645篇 |
1997年 | 526篇 |
1996年 | 431篇 |
1995年 | 319篇 |
1994年 | 334篇 |
1993年 | 231篇 |
1992年 | 208篇 |
1991年 | 147篇 |
1990年 | 109篇 |
1989年 | 109篇 |
1988年 | 100篇 |
1987年 | 84篇 |
1986年 | 63篇 |
1985年 | 73篇 |
1984年 | 52篇 |
1983年 | 23篇 |
1982年 | 43篇 |
1981年 | 27篇 |
1980年 | 24篇 |
1979年 | 19篇 |
1978年 | 19篇 |
1977年 | 15篇 |
1976年 | 6篇 |
1973年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 156 毫秒
11.
Thalia Tsiaka Panagiotis Zoumpoulakis Vassilia J. Sinanoglou Constantinos Makris Georgios A. Heropoulos Antony C. Calokerinos 《Analytica chimica acta》2015
High-energy assisted extraction techniques, like ultrasound assisted extraction (UAE) and microwave assisted extraction (MAE), are widely applied over the last years for the recovery of bioactive compounds such as carotenoids, antioxidants and phenols from foods, animals and herbal natural sources. Especially for the case of xanthophylls, the main carotenoid group of crustaceans, they can be extracted in a rapid and quantitative way with the use of UAE and MAE. 相似文献
12.
Sensitivity improvement of aluminum-based far-ultraviolet nearly guided-wave surface plasmon resonance sensor 下载免费PDF全文
An aluminum (Al) based nearly guided-wave surface plasmon resonance (NGWSPR) sensor is investigated in the far-ultraviolet (FUV) region. By simultaneously optimizing the thickness of Al and dielectric films, the sensitivity of the optimized Al-based FUV-NGWSPR sensor increases from 183°/RIU to 309°/RIU, and its figure of merit rises from 26.47 RIU-1 to 32.59 RIU-1 when the refractive index of dielectric increases from 2 to 5. Compared with a traditional FUV-SPR sensor without dielectric, the optimized FUV-NGWSPR sensor can realize simultaneous improvement of sensitivity and figure of merit. In addition, the FUV-NGWSPR sensor with realistic materials (diamond, Ta2O5, and GaN) is also investigated, and 137.84%, 52.70%, and 41.89% sensitivity improvements are achieved respectively. This work proposes a method for performance improvement of FUV-SPR sensors by exciting nearly guided-wave, and could be helpful for the high-performance SPR sensor in the short-wavelength region. 相似文献
13.
14.
Particularly-shaped silver nanostructures are successfully applied in many scientific fields, such as nanotechnology, catalysis, (nano)engineering, optoelectronics, and sensing. In recent years, the production of shape-controlled silver-based nanostructures and the knowledge around this topic has grown significantly. Hence, on the basis of the most recent results reported in the literature, a critical analysis around the driving forces behind the synthesis of such nanostructures are proposed herein, pointing out the important role of surface-regulating agents in driving crystalline growth by favoring (or opposing) development along specific directions. Additionally, growth mechanisms of the different morphologies considered here are discussed in depth, and critical points highlighted. 相似文献
15.
16.
Yeong‐Tarng Shieh Pei‐Yu Tai Chih‐Chia Cheng 《Journal of polymer science. Part A, Polymer chemistry》2019,57(21):2149-2156
Poly(methyl methacrylate) (PMMA) nanoparticles with a sensitive CO2‐responsive hydrophilic/hydrophobic surface that confers controlled dispersion and aggregation in water were prepared by emulsion polymerization at 50 °C under CO2 bubbling using amphiphilic diblock copolymers of 2‐dimethylaminoethyl methacrylate (DMAEMA) and N‐isopropyl acrylamide (NIPAAm) as an emulsifier. The amphiphilicity of the hydrophobic–hydrophilic diblock copolymer at 50 °C was triggered by CO2 bubbling in water and enabled the copolymer to serve as an emulsifier. The resulting PMMA nanoparticles were spherical, approximately 100 nm in diameter and exhibited sensitive CO2/N2‐responsive dispersion/aggregation in water. Using copolymers with a longer PNIPAAm block length as an emulsifier resulted in smaller particles. A higher concentration of copolymer emulsifier led to particles with a stickier surface. Given its simple preparation and reversible CO2‐triggered amphiphilic behavior, this newly developed block copolymer emulsifier offers a highly efficient route toward the fabrication of sensitive CO2‐stimuli responsive polymeric nanoparticle dispersions. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 2149–2156 相似文献
17.
Yifeng Xiang Xi Tang Changjun Min Guanghao Rui Yan Kuai Fengya Lu Pei Wang Hai Ming Qiwen Zhan Xiaocong Yuan Joseph R. Lakowicz Douguo Zhang 《Annalen der Physik》2020,532(4):1900497
Near-field optical trapping can be realized with focused evanescent waves that are excited at the water–glass interface due to the total internal reflection, or with focused plasmonic waves excited on the water–gold interface. Herein, the performance of these two kinds of near-field optical trapping techniques is compared using the same optical microscope configuration. Experimental results show that only a single-micron polystyrene bead can be trapped by the focused evanescent waves, whereas many beads are simultaneously attracted to the center of the excited region by focused plasmonic waves. This difference in trapping behavior is analyzed from the electric field intensity distributions of these two kinds of focused surface waves and the difference in trapping behavior is attributed to photothermal effects due to the light absorption by the gold film. 相似文献
18.
19.
20.