全文获取类型
收费全文 | 29934篇 |
免费 | 3025篇 |
国内免费 | 2559篇 |
专业分类
化学 | 20668篇 |
晶体学 | 268篇 |
力学 | 1196篇 |
综合类 | 236篇 |
数学 | 4896篇 |
物理学 | 8254篇 |
出版年
2024年 | 33篇 |
2023年 | 300篇 |
2022年 | 520篇 |
2021年 | 735篇 |
2020年 | 858篇 |
2019年 | 1008篇 |
2018年 | 828篇 |
2017年 | 746篇 |
2016年 | 1251篇 |
2015年 | 1262篇 |
2014年 | 1451篇 |
2013年 | 2028篇 |
2012年 | 2256篇 |
2011年 | 2618篇 |
2010年 | 1748篇 |
2009年 | 1673篇 |
2008年 | 2110篇 |
2007年 | 1918篇 |
2006年 | 1881篇 |
2005年 | 1690篇 |
2004年 | 1340篇 |
2003年 | 1062篇 |
2002年 | 1161篇 |
2001年 | 752篇 |
2000年 | 598篇 |
1999年 | 475篇 |
1998年 | 353篇 |
1997年 | 308篇 |
1996年 | 295篇 |
1995年 | 232篇 |
1994年 | 191篇 |
1993年 | 163篇 |
1992年 | 142篇 |
1991年 | 124篇 |
1990年 | 102篇 |
1989年 | 80篇 |
1988年 | 80篇 |
1987年 | 67篇 |
1986年 | 59篇 |
1985年 | 87篇 |
1984年 | 64篇 |
1983年 | 41篇 |
1982年 | 62篇 |
1981年 | 51篇 |
1980年 | 52篇 |
1979年 | 45篇 |
1978年 | 58篇 |
1977年 | 44篇 |
1976年 | 51篇 |
1974年 | 36篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
Martin Kellert Jan-Simon Jeshua Friedrichs Nadine Anke Ullrich Alexander Feinhals Jonas Tepper Peter Lnnecke Evamarie Hey-Hawkins 《Molecules (Basel, Switzerland)》2021,26(7)
The development of novel, tumor-selective and boron-rich compounds as potential agents for use in boron neutron capture therapy (BNCT) represents a very important field in cancer treatment by radiation therapy. Here, we report the design and synthesis of two promising compounds that combine meta-carborane, a water-soluble monosaccharide and a linking unit, namely glycine or ethylenediamine, for facile coupling with various tumor-selective biomolecules bearing a free amino or carboxylic acid group. In this work, coupling experiments with two selected biomolecules, a coumarin derivative and folic acid, were included. The task of every component in this approach was carefully chosen: the carborane moiety supplies ten boron atoms, which is a tenfold increase in boron content compared to the l-boronophenylalanine (l-BPA) presently used in BNCT; the sugar moiety compensates for the hydrophobic character of the carborane; the linking unit, depending on the chosen biomolecule, acts as the connection between the tumor-selective component and the boron-rich moiety; and the respective tumor-selective biomolecule provides the necessary selectivity. This approach makes it possible to develop a modular and feasible strategy for the synthesis of readily obtainable boron-rich agents with optimized properties for potential applications in BNCT. 相似文献
12.
13.
14.
Polypyrrole Shell@3D‐Ni Metal Core Structured Electrodes for High‐Performance Supercapacitors 下载免费PDF全文
Gao‐Feng Chen Yu‐Zhi Su Pan‐Yong Kuang Zhao‐Qing Liu Dao‐Yi Chen Xu Wu Nan Li Prof. Shi‐Zhang Qiao 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(12):4614-4621
Three‐dimensional (3D) nanometal films serving as current collectors have attracted much interest recently owing to their promising application in high‐performance supercapacitors. In the process of the electrochemical reaction, the 3D structure can provide a short diffusion path for fast ion transport, and the highly conductive nanometal may serve as a backbone for facile electron transfer. In this work, a novel polypyrrole (PPy) shell@3D‐Ni‐core composite is developed to enhance the electrochemical performance of conventional PPy. With the introduction of a Ni metal core, the as‐prepared material exhibits a high specific capacitance (726 F g?1 at a charge/discharge rate of 1 A g?1), good rate capability (a decay of 33 % in Csp with charge/discharge rates increasing from 1 to 20 A g?1), and high cycle stability (only a small decrease of 4.2 % in Csp after 1000 cycles at a scan rate of 100 mV s?1). Furthermore, an aqueous symmetric supercapacitor device is fabricated by using the as‐prepared composite as electrodes; the device demonstrates a high energy density (≈21.2 Wh kg?1) and superior long‐term cycle ability (only 4.4 % and 18.6 % loss in Csp after 2000 and 5000 cycles, respectively). 相似文献
15.
16.
17.
18.
19.
Cuixia Cui Yong Gao Dr. Jun Li Chao Yang Meng Liu Prof. Dr. Huile Jin Prof. Dr. Zhenhai Xia Prof. Dr. Liming Dai Prof. Dr. Yong Lei Prof. Dr. Jichang Wang Prof. Dr. Shun Wang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(20):8002-8007
Although tremendous efforts have been devoted to understanding the origin of boosted charge storage on heteroatom-doped carbons, none of the present studies has shown a whole landscape. Herein, by both experimental evidence and theoretical simulation, it is demonstrated that heteroatom doping not only results in a broadened operating voltage, but also successfully promotes the specific capacitance in aqueous supercapacitors. In particular, the electrolyte cations adsorbed on heteroatom-doped carbon can effectively inhibit hydrogen evolution reaction, a key step of water decomposition during the charging process, which broadens the voltage window of aqueous electrolytes even beyond the thermodynamic limit of water (1.23 V). Furthermore, the reduced adsorption energy of heteroatom-doped carbon consequently leads to more stored cations on the heteroatom-doped carbon surface, thus yielding a boosted charge storage performance. 相似文献
20.
Sung Hwan Koo Dong Jun Li Taeyeong Yun Dong Sung Choi Kyung Eun Lee Gil Yong Lee Youngtak Oh Joonwon Lim Suchithra Padmajan Sasikala Ho Jin Lee In Ho Kim Hong Ju Jung Rishabh Jain Sang Ouk Kim 《Particle & Particle Systems Characterization》2019,36(7)
Efficient water electrolysis catalyst is highly demanded for the production of hydrogen as a sustainable energy fuel. It is reported that cobalt derived nanoparticle (CoS2, CoP, CoS|P) decorated reduced graphene oxide (rGO) composite aerogel catalysts for highly active and reliable hydrogen evolution reaction electrocatalysts. 7 nm level cobalt derived nanoparticles are synthesized over graphene aerogel surfaces with excellent surface coverage and maximal expose of active sites. CoS|P/rGO hybrid aerogel composites show an excellent catalytic activity with overpotential of ≈169 mV at a current density of ≈10 mA cm?2. Accordingly, efficient charge transfer is attained with Tafel slope of ≈52 mV dec?1 and a charge transfer resistance (Rct) of ≈12 Ω. This work suggests a viable route toward ultrasmall, uniform nanoparticles decorated graphene surfaces with well‐controlled chemical compositions, which can be generally useful for various applications commonly requiring large exposure of active surface area as well as robust interparticle charger transfer. 相似文献