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981.
Wenchao Zhang Chuangang Hu Zaiping Guo Liming Dai 《Angewandte Chemie (International ed. in English)》2020,59(9):3470-3474
Metal–CO2 batteries have attracted much attention owing to their high energy density and use of greenhouse CO2 waste as the energy source. However, the increasing cost of lithium and the low discharge potential of Na–CO2 batteries create obstacles for practical applications of Li/Na–CO2 batteries. Recently, earth‐abundant potassium ions have attracted considerable interest as fast ionic charge carriers for electrochemical energy storage. Herein, we report the first K–CO2 battery with a carbon‐based metal‐free electrocatalyst. The battery shows a higher theoretical discharge potential (E?=2.48 V) than that of Na–CO2 batteries (E?=2.35 V) and can operate for more than 250 cycles (1500 h) with a cutoff capacity of 300 mA h g?1. Combined DFT calculations and experimental observations revealed a reaction mechanism involving the reversible formation and decomposition of P121/c1‐type K2CO3 at the efficient carbon‐based catalyst. 相似文献
982.
Lei Jiang Haizhen Ding Siyu Lu Ting Geng Guanjun Xiao Bo Zou Hong Bi 《Angewandte Chemie (International ed. in English)》2020,59(25):9986-9991
Photoactivation in CdSe/ZnS quantum dots (QDs) on UV/Vis light exposure improves photoluminescence (PL) and photostability. However, it was not observed in fluorescent carbon quantum dots (CDs). Now, photoactivated fluorescence enhancement in fluorine and nitrogen co‐doped carbon dots (F,N‐doped CDs) is presented. At 1.0 atm, the fluorescence intensity of F,N‐doped CDs increases with UV light irradiation (5 s–30 min), accompanied with a blue‐shift of the fluorescence emission from 586 nm to 550 nm. F,N‐doped CDs exhibit photoactivated fluorescence enhancement when exposed to UV under high pressure (0.1 GPa). F,N‐doped CDs show reversible piezochromic behavior while applying increasing pressure (1.0 atm to 9.98 GPa), showing a pressure‐triggered aggregation‐induced emission in the range 1.0 atm–0.65 GPa. The photoactivated CDs with piezochromic fluorescence enhancement broadens the versatility of CDs from ambient to high‐pressure conditions and enhances their anti‐photobleaching. 相似文献
983.
Chaohai Wang Jeonghun Kim Jing Tang Jongbeom Na Yong‐Mook Kang Minjun Kim Hyunsoo Lim Yoshio Bando Jiansheng Li Yusuke Yamauchi 《Angewandte Chemie (International ed. in English)》2020,59(5):2066-2070
Carbon aerogels (CAs) with 3D interconnected networks hold promise for application in areas such as pollutant treatment, energy storage, and electrocatalysis. In spite of this, it remains challenging to synthesize high‐performance CAs on a large scale in a simple and sustainable manner. We report an eco‐friendly method for the scalable synthesis of ultralight and superporous CAs by using cheap and widely available agarose (AG) biomass as the carbon precursor. Zeolitic imidazolate framework‐8 (ZIF‐8) with high porosity is introduced into the AG aerogels to increase the specific surface area and enable heteroatom doping. After pyrolysis under inert atmosphere, the ZIF‐8/AG‐derived nitrogen‐doped CAs show a highly interconnected porous mazelike structure with a low density of 24 mg cm?3, a high specific surface area of 516 m2 g?1, and a large pore volume of 0.58 cm?3 g?1. The resulting CAs exhibit significant potential for application in the adsorption of organic pollutants. 相似文献
984.
Rachelle S. Jacobson Andrew R. Korte Akos Vertes J. Houston Miller 《Angewandte Chemie (International ed. in English)》2020,59(11):4484-4490
Soot (sometimes referred to as black carbon) is produced when hydrocarbon fuels are burned. Our hypothesis is that polynuclear aromatic hydrocarbon (PAH) molecules are the dominant component of soot, with individual PAH molecules forming ordered stacks that agglomerate into primary particles (PP). Here we show that the PAH composition of soot can be exactly determined and spatially resolved by low‐fluence laser desorption ionization, coupled with high‐resolution mass spectrometry imaging. This analysis revealed that PAHs of 239–838 Da, containing few oxygenated species, comprise the soot observed in an ethylene diffusion flame. As informed by chemical graph theory (CGT), the vast majority of species observed in the sampled particulate matter may be described as benzenoids, consisting of only fused 6‐membered rings. Within that limit, there is clear evidence for the presence of radical PAH in the particulate samples. Further, for benzenoid structures the observed empirical formulae limit the observed isomers to those which are nearly circular with high aromatic conjugation lengths for a given aromatic ring count. These results stand in contrast to recent reports that suggest higher aliphatic composition of primary particles. 相似文献
985.
Pengfei Xia Shaowen Cao Bicheng Zhu Mingjin Liu Miusi Shi Jiaguo Yu Yufeng Zhang 《Angewandte Chemie (International ed. in English)》2020,59(13):5218-5225
Constructing heterojunctions between two semiconductors with matched band structure is an effective strategy to acquire high‐efficiency photocatalysts. The S‐scheme heterojunction system has shown great potential in facilitating separation and transfer of photogenerated carriers, as well as acquiring strong photoredox ability. Herein, a 0D/2D S‐Scheme heterojunction material involving CeO2 quantum dots and polymeric carbon nitride (CeO2/PCN) is designed and constructed by in situ wet chemistry with subsequent heat treatment. This S‐scheme heterojunction material shows high‐efficiency photocatalytic sterilization rate (88.1 %) towards Staphylococcus aureus (S. aureus) under visible‐light irradiation (λ≥420 nm), which is 2.7 and 8.2 times that of pure CeO2 (32.2 %) and PCN (10.7 %), respectively. Strong evidence of S‐scheme charge transfer path is verified by theoretical calculations, in situ irradiated X‐ray photoelectron spectroscopy, and electron paramagnetic resonance. 相似文献
986.
Jos I. Urgel Marco Di Giovannantonio Kristjan Eimre Thorsten G. Lohr Junzhi Liu Shantanu Mishra Qiang Sun Amogh Kinikar Roland Widmer Samuel Stolz Max Bommert Reinhard Berger Pascal Ruffieux Carlo A. Pignedoli Klaus Müllen Xinliang Feng Roman Fasel 《Angewandte Chemie (International ed. in English)》2020,59(32):13281-13287
Cumulene compounds are notoriously difficult to prepare and study because their reactivity increases dramatically with the increasing number of consecutive double bonds. In this respect, the emerging field of on‐surface synthesis provides exceptional opportunities because it relies on reactions on clean metal substrates under well‐controlled ultrahigh‐vacuum conditions. Here we report the on‐surface synthesis of a polymer linked by cumulene‐like bonds on a Au(111) surface via sequential thermally activated dehalogenative C?C coupling of a tribenzoazulene precursor equipped with two dibromomethylene groups. The structure and electronic properties of the resulting polymer with cumulene‐like pentagon–pentagon and heptagon–heptagon connections have been investigated by means of scanning probe microscopy and spectroscopy methods and X‐ray photoelectron spectroscopy, complemented by density functional theory calculations. Our results provide perspectives for the on‐surface synthesis of cumulene‐containing compounds, as well as protocols relevant to the stepwise fabrication of carbon–carbon bonds on surfaces. 相似文献
987.
Yuanxin Li Jingjing Li Jing Sun Haonan He Bo Li Chao Ma Kai Liu Hongjie Zhang 《Angewandte Chemie (International ed. in English)》2020,59(21):8148-8152
Silk‐protein‐based fibers have attracted considerable interest due to their low weight and extraordinary mechanical properties. Most studies on fibrous proteins focus on the recombinant spidroins, but these fibers exhibit moderate mechanical performance. Thus, the development of alternative structural proteins for the construction of robust fibers is an attractive goal. Herein, we report a class of biological fibers produced using a designed chimeric protein, which consists of the sequences of a cationic elastin‐like polypeptide and a squid ring teeth protein. Remarkably, the chimeric protein fibers exhibit a breaking strength up to about 630 MPa and a corresponding toughness as high as about 130 MJ m?3, making them superior to many recombinant spider silks and even comparable to some native counterparts. Therefore, this strategy is a novel concept for exploring bioinspired ultrastrong protein materials through the development of new types of structural chimeric proteins. 相似文献
988.
Minlang Yang In Seob Park Yasuhiro Miyashita Katsunori Tanaka Takuma Yasuda 《Angewandte Chemie (International ed. in English)》2020,59(33):13955-13961
Herein, the universal design of high‐efficiency stimuli‐responsive luminous materials endowed with mechanochromic luminescence (MCL) and thermally activated delayed fluorescence (TADF) functions is reported. The origin of the unique stimuli‐triggered TADF switching for a series of carbazole–isophthalonitrile‐based donor–acceptor (D–A) luminogens is demonstrated based on systematic photophysical and X‐ray analysis, coupled with theoretical calculations. It was revealed that a tiny alteration of the intramolecular D–A twisting in the excited‐state structures governed by the solid morphologies is responsible for this dynamic TADF switching behavior. This concept is applicable to the fabrication of bicolor emissive organic light‐emitting diodes using a single TADF emitter. 相似文献
989.
Tao Zhang Jingxiang Low Jiaguo Yu Alexei M. Tyryshkin Elika Mikmekov Tewodros Asefa 《Angewandte Chemie (International ed. in English)》2020,59(35):15000-15007
A mesoporous TiO2?x material comprised of small, crystalline, vacancy‐rich anatase nanoparticles (NPs) shows unique optical, thermal, and electronic properties. It is synthesized using polymer‐derived mesoporous carbon (PDMC) as a template. The PDMC pores serve as physical barriers during the condensation and pyrolysis of a titania precursor, preventing the titania NPs from growing beyond 10 nm in size. Unlike most titania nanomaterials, during pyrolysis the NPs undergo no transition from the anatase to rutile phase and they become catalytically active reduced TiO2?x. When exposed to a slow electron beam, the NPs exhibit a charge/discharge behavior, lighting up and fading away for an average period of 15 s for an extended period of time. The NPs also show a 50 nm red‐shift in their UV/Vis absorption and long‐lived charge carriers (electrons and holes) at room temperature in the dark, even long after UV irradiation. The NPs as photocatalysts show a good activity for CO2 reduction. 相似文献
990.
Kai Chen Gang Huang Jin‐Ling Ma Jin Wang Dong‐Yue Yang Xiao‐Yang Yang Yue Yu Xin‐Bo Zhang 《Angewandte Chemie (International ed. in English)》2020,59(38):16661-16667
The lithium (Li)–air battery has an ultrahigh theoretical specific energy, however, even in pure oxygen (O2), the vulnerability of conventional organic electrolytes and carbon cathodes towards reaction intermediates, especially O2?, and corrosive oxidation and crack/pulverization of Li metal anode lead to poor cycling stability of the Li‐air battery. Even worse, the water and/or CO2 in air bring parasitic reactions and safety issues. Therefore, applying such systems in open‐air environment is challenging. Herein, contrary to previous assertions, we have found that CO2 can improve the stability of both anode and electrolyte, and a high‐performance rechargeable Li–O2/CO2 battery is developed. The CO2 not only facilitates the in situ formation of a passivated protective Li2CO3 film on the Li anode, but also restrains side reactions involving electrolyte and cathode by capturing O2?. Moreover, the Pd/CNT catalyst in the cathode can extend the battery lifespan by effectively tuning the product morphology and catalyzing the decomposition of Li2CO3. The Li–O2/CO2 battery achieves a full discharge capacity of 6628 mAh g?1 and a long life of 715 cycles, which is even better than those of pure Li–O2 batteries. 相似文献