全文获取类型
收费全文 | 35852篇 |
免费 | 6963篇 |
国内免费 | 7345篇 |
专业分类
化学 | 16505篇 |
晶体学 | 789篇 |
力学 | 1501篇 |
综合类 | 503篇 |
数学 | 2853篇 |
物理学 | 10650篇 |
无线电 | 17359篇 |
出版年
2024年 | 213篇 |
2023年 | 885篇 |
2022年 | 1448篇 |
2021年 | 1643篇 |
2020年 | 1447篇 |
2019年 | 1458篇 |
2018年 | 1215篇 |
2017年 | 1498篇 |
2016年 | 1439篇 |
2015年 | 1943篇 |
2014年 | 2249篇 |
2013年 | 2773篇 |
2012年 | 3136篇 |
2011年 | 3129篇 |
2010年 | 2836篇 |
2009年 | 2988篇 |
2008年 | 3047篇 |
2007年 | 2953篇 |
2006年 | 2617篇 |
2005年 | 2237篇 |
2004年 | 1590篇 |
2003年 | 1269篇 |
2002年 | 1108篇 |
2001年 | 1020篇 |
2000年 | 1076篇 |
1999年 | 581篇 |
1998年 | 347篇 |
1997年 | 273篇 |
1996年 | 257篇 |
1995年 | 185篇 |
1994年 | 189篇 |
1993年 | 202篇 |
1992年 | 145篇 |
1991年 | 97篇 |
1990年 | 112篇 |
1989年 | 106篇 |
1988年 | 87篇 |
1987年 | 72篇 |
1986年 | 60篇 |
1985年 | 38篇 |
1984年 | 36篇 |
1983年 | 24篇 |
1982年 | 24篇 |
1981年 | 26篇 |
1980年 | 14篇 |
1979年 | 10篇 |
1978年 | 7篇 |
1971年 | 7篇 |
1965年 | 11篇 |
1959年 | 6篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
Dr. Shumeng Li Prof. Yuncong Chen Yanping Wu Shankun Yao Hao Yuan Yehong Tan Fen Qi Prof. Weijiang He Prof. Zijian Guo 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(72):e202202680
Organelle-targeted type I photodynamic therapy (PDT) shows great potential to overcome the hypoxic microenvironment in solid tumors. The endoplasmic reticulum (ER) is an indispensable organelle in cells with important biological functions. When the ER is damaged due to the production of reactive oxygen species (ROS), the accumulation of misfolded proteins will interfere with ER homeostasis, resulting in ER stress. Here, an ER-targeted benzophenothiazine-based photosensitizer NBS-ER was presented. ER targeting modification significantly reduced the dark toxicity and improved phototoxicity index (PI). NBS-ER could effectively produce O2−⋅ with near-infrared irradiation, making its phototoxicity under hypoxia close to that under normoxia. Meanwhile, the photoinduced ROS triggered ER stress and induced apoptosis. In addition, NBS-ER possessed excellent photodynamic therapeutic effect in 4T1-tumor-bearing mice. 相似文献
993.
994.
995.
996.
Hydrogenation of acetophenone over nano‐Cu/SiO2 catalysts was investigated. The catalysts, prepared by a liquid precipitation method using various precipitating agents, were characterized using low‐temperature nitrogen adsorption, X‐ray diffraction, temperature‐programmed desorption of ammonia, hydrogen temperature‐programmed reduction, transmission electron microscopy and X‐ray photoelectron spectroscopy. It was found that the catalysts prepared by a homogeneous precipitation method had better activity and stability than those prepared by a co‐precipitation method. The catalyst prepared using urea as precipitating agent had well‐dispersed copper species, high surface area and abundant pore structure. The catalytic performance and mechanism of the Cu/SiO2 catalysts were further studied. It was found that the activity and stability of the catalysts could be improved by adjusting the proportion of Cu+/(Cu+ + Cu0). The sample prepared using urea as precipitating agent presented higher activity and selectivity. Also, the catalyst prepared using urea maintained a high catalytic performance while being continuously used for 150 h under the optimal reaction conditions. 相似文献
997.
Xue Liu Wenting Mao Dr. Jingang Jiang Dr. Xinqing Lu Mingming Peng Dr. Hao Xu Prof. Lu Han Prof. Shun-ai Che Prof. Peng Wu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(17):4520-4529
The conversion of the alkali-treated intergrowth germanosilicate CIT-13 into the single-crystalline high-silica ECNU-21 (named after East China Normal University) zeolite, with a novel topology and a highly crystalline zeolite framework, has been realized through a creative top-down strategy involving a mild alkaline-induced multistep process consisting of structural degradation and reconstruction. Instead of acid treatment, hydrolysis in aqueous ammonia solution not only readily cleaved the chemically weak Ge(Si)−O−Ge bonds located within the interlayer double four ring (D4R) units of CIT-13, but also cleaved the metastable Si−O−Si bonds therein. This led to extensive removal of the D4R units, and also generated silanol groups on adjacent silica-rich layers, which then condensed to form a novel daughter structure upon calcination. Individual oxygen bridges in the reassembled ECNU-21 replaced the germanium-rich D4R units in CIT-13, thereby eliminating the original intergrowth phenomenon along the b axis. With an ordered crystalline structure of 10-ring (R) channels as well as suitable germanium-related Lewis acid sites, ECNU-21 serves as a stable solid Lewis acid catalyst for the shape-selective hydration of ethylene oxide (EO) to ethylene glycol (EG) at greatly reduced H2O/EO ratios and reaction temperature in comparison with the noncatalytic industrial process. 相似文献
998.
Jiameng Li Hang Xu Zian Zhang Yafeng Hao Hanjie Wang Xian Huang 《Advanced functional materials》2020,30(29)
Bioresorbable electronic devices are promising replacements for conventional build‐to‐last electronics in implantable biomedical systems and consumer electronics. However, bioresorbable devices are typically achieved by complex complementary metal oxide semiconductor fabrication processes that minimize exposure to humidity. Emerging printable techniques for bioresorbable electronics demand further improvement in electrical conductivity and mechanical robustness. This paper presents a room‐temperature spontaneous sintering method of bioresorbable inks that contain zinc nanoparticles and anhydride. The entire process can be conducted in atmosphere environment under 90% humidity within 300 min. It has minimum requirement for external heating and special ambient conditions, allowing humidity to trigger the surface chemistry of zinc nanoparticles and spontaneous welding between neighboring nanoparticles. The resulting bioresorbable patterns are highly conductive (σ = 72 400 S m?1) and mechanically robust (>1500 bending cycles) to enable practical applications. A radio circuit achieved through the above method can operate stably over 14 days in air and disappear in water for less than 30 min. The spontaneous room‐temperature sintering represents a rapid and energy‐efficient approach to achieve high‐performance bioresorbable electronics with improved mechanical robustness and electrical performance, leading to broader impacts in the areas of healthcare, information security, and consumer electronics. 相似文献
999.
Haolin Lin Shenhe Fu Zhigui Deng Haiqiong Zhou Hao Yin Zhen Li Zhenqiang Chen 《Annalen der Physik》2019,531(11)
Superoscillation is an intriguing wave phenomenon which enables subwavelength features propagating into far field and hence has potential applications in super‐resolution microscopy as well as particle trapping and manipulation. While previous demonstrations mostly concentrate on designing complicated nanostructures for generating uncontrollable superoscillatory functions, here a new technique which allows for creating polynomially shaped superoscillatory functions that contain phase singularity arrays is demonstrated both theoretically and experimentally. Such a technique is implemented in optical experiments for the first time and controllable superoscillatory lobes with feature much below the diffraction limit is achieved. More importantly, a general theoretical framework, which, to our knowledge, has not been reported before, is developed to show how the created superoscillations propagate to a distance of many Rayleigh ranges and eventually disappear when the distance is sufficiently larger. The validity of the model is confirmed by the experiments. The results may trigger further studies in light field shaping and manipulations in subwavelength scale. 相似文献
1000.