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41.
The absorption spectra and excited state dipole moments of four differently substituted fulvenes have been investigated both experimentally and computationally. The results reveal that the excited state dipole moment of fulvenes reverses in the first excited singlet state when compared to the ground state. The oppositely polarized electron density distributions, which dominate the ground state and the first excited singlet state of fulvenes, respectively, reflect the reversed π-electron counting rules for aromaticity in the two states (4n + 2 vs. 4n, respectively). The results show that substituents indeed influence the polarity of fulvenes in the two states, however, cooperative interactions between the substituents and the fulvene moiety are most pronounced in the ground state. 相似文献
42.
Rondahl Stina Holmgren Pointurier Fabien Ahlinder Linnea Ramebäck Henrik Marie Olivier Ravat Brice Delaunay François Young Emma Blagojevic Ned Hester James R. Thorogood Gordon Nelwamondo Aubrey N. Ntsoane Tshepo P. Roberts Sarah K. Holliday Kiel S. 《Journal of Radioanalytical and Nuclear Chemistry》2018,315(2):395-408
Journal of Radioanalytical and Nuclear Chemistry - This work presents the results for identification of chemical phases obtained by several laboratories as a part of an international nuclear... 相似文献
43.
Nelwamondo Aubrey N. Colletti Lisa P. Lindvall Rachel E. Vesterlund Anna Xu Ning Tan Angela Hiong Jun Eppich Gary R. Genetti Victoria D. Kokwane Banyana L. Lagerkvist Petra Pong Boon Kin Ramebäck Henrik Tandon Lav Rasmussen Gert Varga Zsolt Wallenius Maria 《Journal of Radioanalytical and Nuclear Chemistry》2018,315(2):379-394
Journal of Radioanalytical and Nuclear Chemistry - An international group of laboratories participating in CMX-4 subjected three samples to comparative nuclear forensic analysis using uranium assay... 相似文献
44.
De La Rosa Nathaly Kristiansson Per Nilsson E. J. Charlotta Ros Linus Pallon Jan Skogby Henrik 《Journal of Radioanalytical and Nuclear Chemistry》2018,317(1):253-259
Journal of Radioanalytical and Nuclear Chemistry - Proton-induced reaction (p,α) is one type of nuclear reaction analysis (NRA) suitable especially for light element quantification.... 相似文献
45.
Mikkel Jørgensen Prof. Henrik Grönbeck 《Angewandte Chemie (International ed. in English)》2018,57(18):5086-5089
Heterogeneous catalysts are often designed as metal nanoparticles supported on oxide surfaces. Here, the relation between particle morphology and reaction kinetics is investigated by scaling relation kinetic Monte Carlo simulations using CO oxidation over Pt nanoparticles as a model reaction. We find that different particle morphologies result in vastly different catalytic activities. The activity is strongly affected by kinetic couplings between sites, and a wide site distribution generally enhances the activity. The present study highlights the role of site‐assemblies as a concept that, in addition to isolated active sites, can be used to understand catalytic reactions over nanoparticles. 相似文献
46.
Henrik Birkedal Dieter Schwarzenbach Philip Pattison 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(8):975-977
The crystal structure of the neuroactive artificial dipeptide N‐benzyloxycarbonylprolyl‐d ‐leucine, C19H26N2O5, was solved using synchrotron radiation data collected on a very small crystal (20 × 20 × 380 μm). The molecules form hydrogen‐bonded 21 helices. The acid carbonyl group does not participate in strong hydrogen bonds. This is interpreted as a consequence of close‐packing requirements. 相似文献
47.
We have calculated electronic transitions for sulfuric acid in the ultraviolet region using a hierarchy of coupled cluster response functions and correlation consistent basis sets. Our calculations indicate that the lowest energy singlet transition occurs at 8.42 eV with an oscillator strength of 0.01. The lowest energy triplet state occurs at 8.24 eV. Thus, the cross section of sulfuric acid in the actinic region is likely to be very small and smaller than the upper limit put on this cross section by previous experimental investigations. We estimate the cross section of sulfuric acid in the atmospherically relevant Lyman-alpha region ( approximately 10.2 eV) to be approximately 6 x 10 (-17) cm (2) molecule (-1), a value approximately 30 times larger than the speculative value used in previous atmospheric simulations. We have calculated the J values for photodissociation of sulfuric acid with absorption of visible, UV, and Lyman-alpha radiation, at altitudes between 30 and 100 km. We find that the dominant photodissociation mechanism of sulfuric acid below 70 km is absorption in the visible region by OH stretching overtone transitions, whereas above 70 km, absorption of Lyman-alpha radiation by high energy Rydberg excited states is the favored mechanism. The low lying electronic transitions of sulfuric acid in the UV region do not contribute significantly to its dissociation at any altitude. 相似文献
48.
Dr. Qaisar Nadeem Dr. Giuseppe Meola Dr. Henrik Braband Robin Bolliger Dr. Olivier Blacque Daniel Hernández-Valdés Prof. Dr. Roger Alberto 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(3):1213-1216
The labeling of (bio)molecules with metallic radionuclides such as 99mTc demands conjugated, multidentate chelators. However, this is not always necessary since phenyl rings can directly serve as integrated, organometallic ligands. Bis-arene sandwich complexes are generally prepared by the Fischer–Hafner reaction. In extension of this, we show that [99mTc(η6-C6R6)2]+-type complexes are directly accessible from water and [99mTcO4]−, even using arenes incompatible with Fischer–Hafner conditions. To unambiguously confirm the nature of these unprecedented 99mTc complexes, their rhenium homologous have been prepared by substituting naphthalene ligands in [Re(η6-C10H8)2]+ with the corresponding phenyl groups. The ease with which highly stable [99mTc(η6-C6R6)2]+ complexes are formed under standard labeling conditions enables a multitude of new potential imaging agents based on commercial pharmaceuticals or lead structures. 相似文献
49.
50.
von Euler H Olsson JM Hultenby K Thörne A Lagerstedt AS 《Bioelectrochemistry (Amsterdam, Netherlands)》2003,59(1-2):89-98
INTRODUCTION: Electrochemical treatment (EChT) has been taken under serious consideration as being one of several techniques for local treatment of malignancies. The advantage of EChT is the minimal invasive approach and the absence of serious side effects. Macroscopic, histopathological and ultra-structural findings in liver following a four-electrode configuration (dog) and a two-electrode EChT design (dog and rat) were studied. MATERIALS AND METHODS: 30 female Sprague-Dawley rats and four female beagle dogs were studied with EChT using Platinum:Iridium electrodes and the delivered dose was 5, 10 or 90 C (As). After EChT, the animals were euthanized. RESULTS: The distribution of the lesions was predictable, irrespective of dose and electrode configuration. Destruction volumes were found to fit into a logarithmic curve (dose-response). Histopathological examination confirmed a spherical (rat) and cylindrical/ellipsoidal (dog) lesion. The type of necrosis differed due to electrode polarity. Ultra-structural analysis showed distinct features of cell damage depending on the distance from the electrode. Histopathological and ultra-structural examination demonstrated that the liver tissue close to the border of the lesion displayed a normal morphology. CONCLUSIONS: The in vivo dose-planning model is reliable, even in species with larger tissue mass such as dogs. A multi-electrode EChT-design could obtain predictable lesions. The cellular toxicity following EChT is clearly identified and varies with the distance from the electrode and polarity. The distinct border between the lesion and normal tissue suggests that EChT in a clinical setting for the treatment of liver tumours can give a reliable destruction margin. 相似文献