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951.
Tamae Seo Prof. Dr. Koji Kubota Prof. Dr. Hajime Ito 《Angewandte Chemie (International ed. in English)》2023,62(42):e202311531
The combination of a nickel(II) catalyst and a mechanoredox catalyst under ball-milling conditions promotes mechanical-force-driven C−N cross-coupling reactions. In this nickel(II)/mechanoredox cocatalyst system, the modulation of the oxidation state of the nickel center, induced by piezoelectricity, is used to facilitate a highly efficient aryl-amination reaction, which is characterized by a broad substrate scope, an inexpensive combination of catalysts (NiBr2 and BaTiO3), short reaction times, and an almost negligible quantity of solvents. Moreover, this reaction can be readily up-scaled to the multi-gram scale, and all synthetic operations can be carried out under atmospheric conditions without the need for complicated reaction setups. Furthermore, this force-induced system is suitable for excitation-energy-accepting molecules and poorly soluble polyaromatic substrates that are incompatible with solution-based nickel(II)/photoredox cocatalysts. 相似文献
952.
Sanghyup Seo Joonho Jung Prof. Dr. Hyunwoo Kim 《Angewandte Chemie (International ed. in English)》2023,62(28):e202303853
Novel P,O-type ligands, N-disulfonyl bicyclic bridgehead phosphorus triamides, were synthesized and utilized in Pd-catalyzed hydrosilylation involving tertiary silanes, unactivated alkenes, and conjugated dienes. The ligand displayed a remarkable level of reactivity for alkene hydrosilylation with tertiary silanes and its use resulted in a significant improvement in the regioselectivity of diene hydrosilylation towards 1,2-hydrosilylation. X-ray crystallographic analysis confirmed the bidentate nature of the ligand, with coordination of phosphorus and oxygen. Control experiments provided evidence for the formation of Pd0 species and the reversibility of Pd−H insertion in the reaction mechanism. Density functional theory (DFT) computations supported the importance of the hemilabile P,O ligand in stabilizing both the rate-determining transition state of Pd−H insertion and the transition state of reductive elimination that determines the regioselectivity. 相似文献
953.
Hyung Ju Kim Yong Seok Kim Min Ho Seo Sung Mook Choi Joungmo Cho George W. Huber Won Bae Kim 《Electrochemistry communications》2010,12(1):32-35
Electrochemical reduction of oxygen is studied over a novel nanowire network catalyst made of highly-dispersed Pt nanoparticles into electrospun Pt nanowire network architecture, which shows an excellent mass activity increase by 50% or higher per equal Pt mass than the conventional cathode electrocatalysts of Pt/C in polymer electrolyte membrane fuel cells. 相似文献
954.
Organic Dyes with Well‐Defined Structures for Highly Efficient Dye‐Sensitised Solar Cells Based on a Cobalt Electrolyte 下载免费PDF全文
Dr. Kang Deuk Seo In Tack Choi Prof. Hwan Kyu Kim 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(42):14804-14811
Seven SGT organics dyes, containing bis‐dimethylfluoreneyl amino groups with a dialkoxyphenyl unit as an electron donor and a cyanoacrylic acid group as an anchoring group, connected with oligothiophenes, fused thiophenes and benzothiadiazoles as π‐bridges, were designed and synthesised for applications in dye‐sensitised solar cells (DSSCs). The photovoltaic performance of DSSCs based on organic dyes with oligothiophenes depends on the molecular structure of the dyes, in terms of the length change of the π‐bridging units. The best performance was found with a π‐bridge length of about 6 Å. To further enhance the photovoltaic performance associated with this concept, cyclopenta[1,2‐b:5,4‐b′]dithiophene (CPDT) and benzothiadiazole were introduced into the π‐bridge unit. As a result, the DSSC based on the organic dye containing the CPDT moiety showed the best photovoltaic performance with a short‐circuit photocurrent density (Jsc) of 14.1 mA cm?2, an open‐circuit voltage (Voc) of 0.84 V and a fill factor (FF) of 0.72, corresponding to an overall conversion efficiency (η) of 8.61 % under standard AM 1.5 irradiation. 相似文献
955.
Determination of a novel phosphodiesterase4 inhibitor, 3‐[1‐(3cyclopropylmethoxy‐4‐difluoromethoxybenzyl)‐1H‐pyrazol‐3‐yl]‐benzoic acid (PDE‐423) in rat plasma using liquid chromatography–tandem mass spectrometry 下载免费PDF全文
Woon‐Ki Cho Hyewon Seo Sung Heum Choi Hyun Jeong Kwak Hyae Gyeong Cheon Dong Ju Jeon Sang Kyum Kim Myung Ae Bae Jin Sook Song 《Biomedical chromatography : BMC》2015,29(3):321-324
A method for determining a novel phosphodiesterase‐4 inhibitor, 3‐[1‐(3cyclopropylmethoxy‐4‐difluoromethoxybenzyl)‐1H‐pyrazol‐3‐yl]‐benzoic acid (PDE‐423), in rat plasma was developed and validated using liquid chromatography–tandem mass spectrometry for further pharmacokinetic study for development as a novel anti‐asthmatic drug. PDE‐423 in the concentration range of 0.02–10 µg/mL was linear with a correlation coefficient of >0.99, and the mean intra‐ and inter‐assay precisions of the assay were 7.50 and 3.86%, respectively. The validated method was used successfully for a pharmacokinetic study of PDE‐423 in rats. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
956.
Random‐Graft Polymer‐Directed Synthesis of Inorganic Mesostructures with Ultrathin Frameworks 下载免费PDF全文
Dr. Changbum Jo Dr. Yongbeom Seo Dr. Kanghee Cho Jaeheon Kim Hye Sun Shin Munhee Lee Jeong‐Chul Kim Prof. Sang Ouk Kim Prof. Jeong Yong Lee Prof. Hyotcherl Ihee Prof. Ryong Ryoo 《Angewandte Chemie (International ed. in English)》2014,53(20):5117-5121
A widely employed route for synthesizing mesostructured materials is the use of surfactant micelles or amphiphilic block copolymers as structure‐directing agents. A versatile synthesis method is described for mesostructured materials composed of ultrathin inorganic frameworks using amorphous linear‐chain polymers functionalized with a random distribution of side groups that can participate in inorganic crystallization. Tight binding of the side groups with inorganic species enforces strain in the polymer backbones, limiting the crystallization to the ultrathin micellar scale. This method is demonstrated for a variety of materials, such as hierarchically nanoporous zeolites, their aluminophosphate analogue, TiO2 nanosheets of sub‐nanometer thickness, and mesoporous TiO2, SnO2, and ZrO2. This polymer‐directed synthesis is expected to widen our accessibility to unexplored mesostructured materials in a simple and mass‐producible manner. 相似文献
957.
958.
Thanh Luan Nguyen Seyeong Song Seo‐Jin Ko Hyosung Choi Ji‐Eun Jeong Taehyo Kim Sungu Hwang Jin Young Kim Han Young Woo 《Journal of polymer science. Part A, Polymer chemistry》2015,53(7):854-862
A series of benzodithiophene‐thiophene‐based alternating copolymers were synthesized with different side‐chains, and their photovoltaic characteristics were examined. The choice of solubilizing side‐chains influences significantly the chain conformation, frontier orbital energy levels, intermolecular organization, and the resulting optical, morphological, and photovoltaic properties. The incorporation of an e‐withdrawing carbonyl group in the side‐chain decreased the highest occupied molecular orbital (HOMO, ca. ?5.4 eV) level and improved the chain planarity through intrachain hydrogen bonding. The shortest π–π stacking distance (3.72 Å) was also measured for the alkylcarbonyl‐substituted BDTCOT:PC71BM blended film by two dimensional grazing incidence X‐ray scattering. With compared to other polymers, the BDTCOT:PC71BM device showed a substantially improved open‐circuit voltage and short‐circuit current density, leading to a 4.66% power conversion efficiency. The side‐chains need to be designed to be multifunctional to induce a deep HOMO level and chain planarity (for interchain ordering) as well as good solution processability. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 854–862 相似文献
959.
Pradip Kumar Tapaswi Myeon‐Cheon Choi Young Sik Jung Hun Jeong Cho Deok Jin Seo Chang‐Sik Ha 《Journal of polymer science. Part A, Polymer chemistry》2014,52(16):2316-2328
A new series of fully aliphatic polyimide (API) based on a novel aliphatic dianhydride monomer‐2,2′‐(1,4‐piperazinediyl)‐disuccinic anhydride (PDA), in which two units of succinic anhydride have been connected by an aliphatic heterocyclic piperazine spacer that possesses aminomethylene (‐NCH2) moiety in the aliphatic/alicylic backbone capable of inducing charge transfer (CT) interactions in the polyimide network, was successfully synthesized. The APIs were soluble in common polar organic solvents. The polyimide films of PDA with alicyclic diamines were almost colorless. T10 (temperature of 10% weight loss) of APIs were ranged from 299–418 °C and Tg of API3‐API6 were in the temperature range of 170 to 237 °C. The light‐colored polyimide films of API3‐API6 possessed good mechanical properties with tensile strength of 54–72 Mpa, tensile modulus of 1.6–2.3 Gpa and elongation at break of 4–9%. The polyimide films of API3‐API6 were highly flexible and free‐standing which is quite rare in fully APIs. The dielectric constant of one of the synthesized API (API4) was as low as 2.14. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 2316–2328 相似文献
960.
Jinhee Lee Jaewon Heo Changjun Park Byung‐Kwon Kim Juhyoun Kwak Myungeun Seo Sang Youl Kim 《Journal of polymer science. Part A, Polymer chemistry》2014,52(18):2692-2702
We report synthesis of a series of new triarylamine‐containing AB‐type monomers and their polymers via nucleophilic aromatic substitution (SNAr) reaction. Monomers consisting of a hydroxyl group at the para position of the nitrogen group in one phenyl ring and a fluorine leaving group at the para position in another phenyl ring were synthesized via palladium‐catalyzed amination reaction. The fluorine leaving group was activated by trifluoromethyl group at the ortho position and an electron‐withdrawing group (EWG) introduced at the para position of the unsubstituted phenyl ring that enabled control over monomer reactivity. SNAr reaction of the monomers successfully produced corresponding poly(arylene ether)s with pendant EWGs that exhibited good solubility and thermal stability. Optical and electrochemical properties of the polymers were also affected by incorporation of EWGs. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 2692‐2702 相似文献