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961.
Toshiro Tani Masaru Oda Hiroshi Sakai Yoshinori Itoh Masafumi Yohda 《Journal of luminescence》2011,131(3):519-522
We report single molecule spectroscopic evidence of FRET in CdSe quantum dot (QD) conjugated with Cy5-labeled molecular chaperone systems in buffer solutions. Donor QDs are core-shell type nanocrystals covered with organic surfactants on their outermost surfaces, i.e. CdSe/ZnS/TOPO’s. As prototype molecular chaperones, we adopt prefoldins (PFDs), on which Cy5’s are labeled as acceptors. Donor QDs possess two-fold degenerate emission dipoles perpendicular to the c-axis, due to their Wurtzite crystal structures, while acceptor Cy5’s possess linear absorption and emission dipoles. Thus, their combination provides novel features to those in conventional FRET systems. PFDs are jellyfish-shaped hexameric co-chaperones of group II chaperonins, which recognize hydrophobic portions of denatured proteins and encapsulate them within their central cavities. Hence, PFDs will also capture the CdSe/ZnS/TOPO QDs due to its surface similarity to the denatured proteins. By introducing simple microscope setup for single QD-PFD-Cy5 spectroscopy, we have successfully captured the emission spectra in FRET regime. We also have observed peculiar features in time evolution profiles of single QD emissions conjugated with Cy5-labeled PFDs under polarization modulation measurements. Notable point of our hybrid conjugates is that they are biochemically in living action. We describe our present results in relation to possible protein reactions. 相似文献
962.
The present work puts forward the results of the recordings carried out under high resolution by conventional, photographic spectroscopy and modern analysis of thirteen bands with v′ = 7-12 and v″ = 16-24 of the fourth-positive (A1Π → X1Σ+) band system. The current investigations include the region of the observed 13C16O molecule spectrum, much greater now than before. Especially, new transitions connected with not hitherto observed v′ = 12 vibrational level of the A1Π state, were recorded and studied. Moreover, the region of perturbations observed in the upper state of the fourth-positive system was significantly enlarged. The observed perturbations were confronted with those predicted from theoretical calculations. 相似文献
963.
Yaodong Zhang Yun ZhangJuanjuan Jiang Li LiCaihong Yu Tingting Hei 《Applied Surface Science》2011,257(7):2712-2716
Protein molecules immobilized on a hydrophobic polystyrene microplate by passive adsorption lose their activity and suffer considerable denaturation. In this paper, we report a thorough evaluation of a protocol for enzyme immobilization on a microplate with relatively inexpensive reagents, involving glutaraldehyde coupling and spacer molecules, and employing β-glucosidase as a model enzyme. The recommended conditions for the developed method include 2.5% glutaraldehyde to activate the reaction, 1% chitosan in an HAc solution to increase the binding capacity, 2% bovine serum albumin to block non-specific binding sites, and 0.1 M NaBH4 to stabilize Schiff's base intermediates. Using this method, the amount of β-glucosidase immobilized on amino-microplate was 24-fold with chitosan than without spacer molecules. The procedure is efficient and quite simple, and may thus have potential applications in biosensing and bioreactor systems. 相似文献
964.
Wenlang Li Qiuyi Huang Zhu Mao Juan Zhao Huiyan Wu Junru Chen Zhan Yang Yang Li Zhiyong Yang Yi Zhang Matthew P. Aldred Zhenguo Chi 《Angewandte Chemie (International ed. in English)》2020,59(9):3739-3745
Soft luminescent materials are attractive for optoelectronic applications, however, switching dominant chromophores for property enrichment remains a challenge. Herein, we report the first case of a soft organic molecule (DOS) featuring selective expression of chromophores. In response to various external stimuli, different chromophores of DOS can take turns working through conformation changes, exhibiting full‐colour emissions peaking from 469 nm to 583 nm from ten individual single crystals. Dynamic triplet‐exciton behaviours including thermally activated delayed fluorescence (TADF), room‐temperature phosphorescence (RTP), mechanoluminescence (ML), and distinct mechano‐responsive luminescence (MRL) can all be realized. This novel designed DOS molecule provides a multifunctional platform for detection of volatile organic compounds (VOCs), multicolour dynamic displays, sensing, anticounterfeiting, and hopefully many others. 相似文献
965.
Andreas Heilmann Jamie Hicks Petra Vasko Jose M. Goicoechea Simon Aldridge 《Angewandte Chemie (International ed. in English)》2020,59(12):4897-4901
Anionic molecular imide complexes of aluminium are accessible via a rational synthetic approach involving the reactions of organo azides with a potassium aluminyl reagent. In the case of K2[( NON )Al(NDipp)]2 ( NON =4,5‐bis(2,6‐diisopropylanilido)‐2,7‐di‐tert‐butyl‐9,9‐dimethyl‐xanthene; Dipp=2,6‐diisopropylphenyl) structural characterization by X‐ray crystallography reveals a short Al?N distance, which is thought primarily to be due to the low coordinate nature of the nitrogen centre. The Al?N unit is highly polar, and capable of the activation of relatively inert chemical bonds, such as those found in dihydrogen and carbon monoxide. In the case of CO, uptake of two molecules of the substrate leads to C?C coupling and C≡O bond cleavage. Thermodynamically, this is driven, at least in part, by Al?O bond formation. Mechanistically, a combination of quantum chemical and experimental observations suggests that the reaction proceeds via exchange of the NR and O substituents through intermediates featuring an aluminium‐bound isocyanate fragment. 相似文献
966.
Chun‐Kai Wang Xiaozhou Che Yuan‐Chih Lo Ya‐Ze Li Yung‐Hao Wang Stephen R. Forrest Shun‐Wei Liu Ken‐Tsung Wong 《化学:亚洲杂志》2020,15(16):2520-2531
Four new donor‐acceptor‐acceptor’ (D‐A‐A’)‐configured donors, CPNT , DCPNT , CPNBT , and DCPNBT equipped with naphtho[1,2‐c:5,6‐c′]bis([1,2,5]‐thiadiazole) (NT) or naphtho[2,3‐c][1,2,5]thiadiazole (NBT) as the central acceptor (A) unit bridging triarylamine donor (D) and cyano or dicyanovinylene acceptor (A’), were synthesized and characterized. All molecules exhibit bathochromic absorption shifts as compared to those of the benzothiadiazole (BT)‐based analogues owing to improved electron‐withdrawing and quinoidal character of NT and NBT cores that lead to stronger intramolecular charge transfer. Favorable energy level alignments with C70, together with the good thermal stability and the antiparallel dimeric packing render CPNT and DCPNT suitable donors for vacuum‐processed organic photovoltaics (OPV)s. OPVs based on DCPNT : C70 active layers displayed the best power conversion efficiency (PCE)=8.3%, along with an open circuit voltage of 0.92 V, a short circuit current of 14.5 mA cm?2 and a fill factor of 62% under 1 sun intensity, simulated AM1.5G illumination. Importantly, continuous light‐soaking with AM 1.5G illumination has verified the durability of the devices based on CPNT :C70 and DCPNT : C70 as the active blends. The devices were examined for their feasibility of indoor light harvesting under 500 lux illumination by a TLD‐840 fluorescent lamp, giving PCE=12.8% and 12.6%, respectively. These results indicate that the NT‐based D‐A‐A’‐type donors CPNT and DCPNT are potential candidates for high‐stability vacuum‐processed OPVs suitable for indoor energy harvesting. 相似文献
967.
Zhongbo Zhang Wei Sun Huanxiang Zhang Xinxiong Li Fei Yu Jia Zhu Xianggao Li Qichun Zhang 《化学:亚洲杂志》2020,15(14):2198-2202
Two novel molecules TAP and TAH with pronounced reversible halochromic properties have been synthesized and fully characterized. Their butterfly‐like structures have been confirmed through single‐crystal X‐ray diffraction. Their UV‐Vis absorption after protonation dramatically red‐shifted with naked‐eye‐visible color change in a very dilute concentration of 10?5 M. Note that the original color of the solution can be recovered after the neutralization with a base. 相似文献
968.
Phil Holzmeister Andreas Gietl Prof. Dr. Philip Tinnefeld 《Angewandte Chemie (International ed. in English)》2014,53(22):5685-5688
Despite common presumption due to fast photodestruction pathways through higher excited states, we show that further improvement of photostability is still achievable with diffusion‐limited photoprotection formulas. Single‐molecule fluorescence spectroscopy reveals that thiolate ions effectively quench triplet states of dyes by photoinduced electron transfer. Interestingly, this reaction rarely yields a radical anion of the dye, but direct return to the ground state is promoted by an almost instantaneous back electron transfer (geminate recombination). This type of mechanism is not detected for commonly used reductants such as ascorbic acid and trolox. The mechanism avoids the formation of radical cations and improves the photostability of single fluorophores. We find that a combination of β‐mercaptoethanol and classical reducing and oxidizing systems yields the best results for several dyes including Atto532 and Alexa568. 相似文献
969.
Inside Cover: Identification and X‐ray Co‐crystal Structure of a Small‐Molecule Activator of LFA‐1‐ICAM‐1 Binding (Angew. Chem. Int. Ed. 17/2014)
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970.
Motion Capture and Manipulation of a Single Synthetic Molecular Rotor by Optical Microscopy
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Dr. Tomohiro Ikeda Takahiro Tsukahara Prof. Ryota Iino Prof. Masayuki Takeuchi Prof. Hiroyuki Noji 《Angewandte Chemie (International ed. in English)》2014,53(38):10082-10085
Single‐molecule imaging and manipulation with optical microscopy have become essential methods for studying biomolecular machines; however, only few efforts have been directed towards synthetic molecular machines. Single‐molecule optical microscopy was now applied to a synthetic molecular rotor, a double‐decker porphyrin (DD). By attaching a magnetic bead (ca. 200 nm) to the DD, its rotational dynamics were captured with a time resolution of 0.5 ms. DD showed rotational diffusion with 90° steps, which is consistent with its four‐fold structural symmetry. Kinetic analysis revealed the first‐order kinetics of the 90° step with a rate constant of 2.8 s?1. The barrier height of the rotational potential was estimated to be greater than 7.4 kJ mol?1 at 298 K. The DD was also forcibly rotated with magnetic tweezers, and again, four stable pausing angles that are separated by 90° were observed. These results demonstrate the potency of single‐molecule optical microscopy for the elucidation of elementary properties of synthetic molecular machines. 相似文献