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991.
Nishiyama Y Endo Y Nemoto T Utsumi H Yamauchi K Hioka K Asakura T 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2011,208(1):44-48
Substantial resolution and sensitivity enhancements of solid-state (1)H detected (14)N HMQC NMR spectra at very fast MAS rates up to 80 kHz, in a 1mm MAS rotor, are presented. Very fast MAS enhances the (1)H transverse relaxation time and efficiently decouples the (1)H-(14)N interactions, both effects leading to resolution enhancement. The micro-coil contributes to the sensitivity increase via strong (14)N rf fields and high sensitivity per unit volume. (1)H-(14)N HMQC 2D spectra of glycine and glycyl-L-alanine at 70 kHz MAS at 11.7 T are observed in a few minutes with a sample volume of 0.8 μL. 相似文献
992.
In this Letter, a scaled-down silicon-on-insulator (SOI) metal-oxide-semiconductor field-effect transistor (MOSFET) is characterized as a photon detector, where photogenerated individual holes are trapped below the negatively biased gate and modulate stepwise the electron current flowing in the bottom channel induced by the positive substrate bias. The output waveforms exhibit clear separation of current levels corresponding to different numbers of trapped holes. Considering this capability of single-hole counting, a small dark count of less than 0.02 s(-1) at room temperature, and low operation voltage of 1 V, SOI MOSFET could be a unique photon-number-resolving detector if the small quantum efficiency were improved. 相似文献
993.
Kobayashi H Morita H Yamauchi M Ikeda R Kitagawa H Kubota Y Kato K Takata M 《Journal of the American Chemical Society》2011,133(29):11034-11037
We report the first example of nanosize-induced hydrogen storage in a metal that does not absorb hydrogen in its bulk form. Rhodium particles with diameters of <10 nm were found to exhibit hydrogen-storage capability, while bulk Rh does not absorb hydrogen. Hydrogen storage was confirmed by in situ powder X-ray diffraction, solid-state (2)H NMR, and hydrogen pressure-composition isotherm measurements. The hydrogen absorption capacity could be tuned by controlling the particle size. 相似文献
994.
Ozawa H Yi X Fujigaya T Niidome Y Asano T Nakashima N 《Journal of the American Chemical Society》2011,133(37):14771-14777
We describe the design, synthesis, and characterization of a supramolecular hybrid of gold nanometals and semiconducting single-walled carbon nanotubes (SWNTs) wrapped by a porphyrin-fluorene copolymer (1), as well as fabrication of a thin-film transistor (TFT) device using the hybrid. Photoluminescence mapping revealed that the copolymer selectively dissolved SWNTs with chirality indices of (8,6), (8,7), (9,7), (7,6), and (7,5); dissolution of (8,6), and (8,7) SWNTs was especially efficient. The solubilized SWNTs were connected to gold nanoparticles (AuNPs) via a coordination bond to prepare a supramolecular hybrid composed of AuNPs/copolymer 1-wrapped SWNTs, which were studied by atomic force and scanning and transmission electron microscopies. A fabricated TFT device using the semiconducting SWNTs/copolymer 1 shows evident p-type transport with an On/Off ratio of ~10(5). The transport properties of the TFT changed after coordination of the AuNPs with the SWNTs/copolymer 1. 相似文献
995.
In this study, we demonstrate the fabrication of an electrochemically active nanofiber mat that is a composite of high‐performance poly(imide sulfonate) (PIS) and polyaniline (PANI). First, a nonconductive nanofiber mat comprising nanofibers having diameters of ca. 300 nm was fabricated by the electrospinning of ionomeric PIS in N,N‐dimethylformamide (DMF). Then, the nanofibers were modified using PANI, which was synthesized by the oxidative polymerization of aniline, yielding an electrochemically active nanofiber mat having a diameter of ca. 350 nm. It was confirmed that PANI was successfully incorporated onto the PIS nanofiber mats by X‐ray photoelectron spectroscopy. Subsequently, we conducted electrochemical measurements of the PANI‐modified nanofiber mats using a tailor‐made attachment in which the working electrode gently comes in contact with the nanofiber mat surface. This attachment was observed to be widely useful in the cyclic voltammetry measurements related to redox‐active nanofibers. These observations are expected to contribute to the advancements in application development of the electrochemically active nanofiber mats. 相似文献
996.
Rika Okuma Tomoki Kuwahara Takafumi Yoshikane Mizuki Watanabe Patricia Dranchak James Inglese Satoshi Shuto Yuki Goto Hiroaki Suga 《化学:亚洲杂志》2020,15(17):2631-2636
Here we report the construction of an mRNA‐encoded library of thioether‐closed macrocyclic peptides by using an N‐chloroacetyl‐cyclopropane‐containing exotic initiator whose structure is more constrained than the ordinary N‐chloroacetyl‐α‐amino acid initiators. The use of such an initiator has led to a macrocycle library with significantly suppressed population of lariat‐shaped species compared with the conventional libraries. We previously used a conventional library and identified a small lariat thioether‐macrocycle with a tail peptide with a C‐terminal free Cys whose sidechain plays an essential role in potent inhibitory activity against a parasitic model enzyme, phosphoglycerate mutase. On the other hand, the cyclopropane‐containing macrocycle library has yielded a larger thioether‐macrocycle lacking a free Cys residue, which exhibits potent inhibitory activity to the same enzyme with a different mode of action. This result indicates that such a cyclopropane‐containing macrocycle library would allow us to access mechanistically distinct macrocycles. 相似文献
997.
Shinji Tanimori Ushio Inaba Yoshihiro Kato Haruna Ura Hiroaki Kashiwagi Takeshi Nishimura Mitsunori Kirihata 《Research on Chemical Intermediates》2014,40(6):2157-2164
This paper reports our recent results from synthesis of some useful heterocycles, for example oxazolidinones, indoles, and quinoxalinones, by transition metal-catalyzed cascade processes. The scope and limitations of these procedures and the reaction mechanism for formation of the heterocycles are also discussed. 相似文献
998.
Silylation Improves the Photodynamic Activity of Tetraphenylporphyrin Derivatives In Vitro and In Vivo
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Prof. Hiroaki Horiuchi Prof. Masahiro Hosaka Hiroyuki Mashio Motoki Terata Prof. Shintaro Ishida Prof. Soichiro Kyushin Prof. Tetsuo Okutsu Prof. Toshiyuki Takeuchi Prof. Hiroshi Hiratsuka 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(20):6054-6060
The effects of silyl and hydrophilic groups on the photodynamic properties of tetraphenylporphyrin (TPP) derivatives have been studied in vitro and in vivo. Silylation led to an improvement in the quantum yield of singlet oxygen sensitization for both sulfo and carboxy derivatives, although the silylation did not affect other photophysical properties. Silylation also improved the cellular uptake efficiency for both sulfo and carboxy derivatives, enhancing the in vitro photodynamic activity of the photosensitizer in U251 human glioma cells. The carboxy derivative (SiTPPC4) was found to show higher cellular uptake efficiency and in vitro photodynamic activity than the corresponding sulfo derivative (SiTPPS4), which indicates that the carboxy group is a more promising hydrophilic group than the sulfo group in the silylated porphyrin. SiTPPC4 was found to show high selective accumulation efficiency in tumors, although almost no tumor selectivity was observed for the nonsilylated porphyrin. The concentration of SiTPPC4 in tumors was 13 times higher than that in muscle 12 h after drug administration. We also studied tumor response after treatment and found that silylation enhanced in vivo photodynamic activity significantly. SiTPPC4 shows higher photodynamic activity than NPe6 with white light irradiation. 相似文献
999.
Katsuhito Suzuki Akihiro Sato Hiroaki Okumura Tadafumi Hashimoto Antonio Norio Nakagaito Hiroyuki Yano 《Cellulose (London, England)》2014,21(1):507-518
Novel high-strength, micro-fibrillated cellulose (MFC)-reinforced polypropylene (PP) composites were prepared using maleic anhydride polypropylene (MAPP) and a cationic polymer having a primary amino group (CPPA) as coupling agents. Un-dried kraft pulp was micro-fibrillated into nano- to submicron-wide fibrils by kneading with powdered PP and the coupling agents via a twin-screw extruder. The composites were prepared by injection molding. The MFC-reinforced PP composites containing both coupling agents MAPP and CPPA (combination system) showed extremely high mechanical strength compared with the MFC-reinforced composite containing only MAPP. The tensile strength of a 30 wt% MFC-PP composite containing the combination system was 27 % higher than that of the composite containing only MAPP, and more than 60 % higher than that of neat PP. In addition, the heat distortion temperature, under a 1.82-MPa flexural load, of the composite with the combination system was 17 °C higher than that of the composite with MAPP only, and 34 °C higher than that of neat PP. The anisotropy of the modulus and strength in the injection-molded MFC composites was lower than that of glass fiber-reinforced PP. 相似文献
1000.
Dimeric Tetrathiafulvalene Linked to pseudo‐ortho‐[2.2]Paracyclophane: Chiral Electrochromic Properties and Use as a Chiral Dopant
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Kosuke Kobayakawa Dr. Masashi Hasegawa Hiroaki Sasaki Junta Endo Dr. Hideyo Matsuzawa Dr. Katsuya Sako Dr. Jun Yoshida Dr. Yasuhiro Mazaki 《化学:亚洲杂志》2014,9(10):2751-2754
A dimeric tetrathiafulvalene installed into a chiral pseudo‐ortho‐[2.2]paracyclophane framework was synthesized as a novel chiral electrochromic material. This compound exhibited pronounced chiroptical properties in the UV‐Vis‐NIR range depending on its redox states without racemization. Each enantiomer was examined as a chiral dopant for nematic liquid crystals (LCs), and the induced helicity of the LC solvent was in accord with that of the tetrathiafulvalene compound. 相似文献