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901.
Diastereoselective Synthesis of Open‐Chain Secondary Alkyllithium Compounds and Trapping Reactions with Electrophiles 下载免费PDF全文
Dr. Guillaume Dagousset Kohei Moriya Rasmus Mose Dr. Guillaume Berionni Prof. Dr. Konstantin Karaghiosoff Prof. Dr. Paul Knochel 《Angewandte Chemie (International ed. in English)》2014,53(5):1425-1429
A practical stereoselective iodide–lithium exchange was used in the first general preparation of functionalized stereodefined acyclic secondary nonstabilized lithium reagents from the corresponding secondary alkyl iodides. These lithium reagents react with various electrophiles including carbon electrophiles with high retention of configuration. Kinetic data on the configurational stability of these acyclic alkyllithium reagents are given. This methodology offers a new entry to chiral synthons for the stereoselective synthesis of open‐chain molecules. 相似文献
902.
Dr. Martin Rahm Guillaume Bélanger‐Chabot Prof. Ralf Haiges Prof. Karl O. Christe 《Angewandte Chemie (International ed. in English)》2014,53(27):6893-6897
The elusive nitryl cyanide, NCNO2, has been synthesized and characterized. It was prepared in good yield, isolated by fractional condensation, characterized by NMR and vibrational spectroscopy, and studied by theoretical calculations. Nitryl cyanide holds promise as a high energy density material (HEDM) and might also prove useful as a HEDM building block. The simplicity and inherent stability of nitryl cyanide, together with the known multitude of nitriles in interstellar space, suggest that the compound might also be a potential candidate for observations in atmospheric and interstellar chemistry. 相似文献
903.
Aurlien Chardon Arnaud Osi Damien Mahaut Thu‐Hong Doan Nikolay Tumanov Johan Wouters Luca Fusaro Benoît Champagne Guillaume Berionni 《Angewandte Chemie (International ed. in English)》2020,59(30):12402-12406
A highly bent triarylborane, 9‐boratriptycene, was generated in solution by selective protodeboronation of the corresponding tetra‐aryl boron ate complex with the strong Brønsted acid HNTf2. The iptycene core confers enhanced Lewis acidity to 9‐boratriptycene, making it unique in terms of structure and reactivity. We studied the stereoelectronic properties of 9‐boratriptycene by quantifying its association with small N‐ and O‐centered Lewis bases, as well as with sterically hindered phosphines. The resultant Lewis adducts exhibited unique structural, spectroscopic, and photophysical properties. Beyond the high pyramidalization of the 9‐boratriptycene scaffold and its low reorganization energy upon Lewis base coordination, quantum chemical calculations revealed that the absence of π donation from the triptycene aryl rings to the boron vacant pz orbital is one of the main reasons for its high Lewis acidity. 相似文献
904.
905.
Dr. Chen Zhang Dr. Pierre-Yves Fortin Guillaume Barnoin Xue Qin Xing Wang Dr. Alvaro Fernandez Alvarez Dr. Christian Bijani Dr. Marie-Lise Maddelein Dr. Catherine Hemmert Dr. Olivier Cuvillier Prof. Dr. Heinz Gornitzka 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(29):12160-12166
906.
Sebastian Leubner Robert Stäglich Julia Franke Jannick Jacobsen Jonas Gosch Dr. Renée Siegel Dr. Helge Reinsch Prof. Dr. Guillaume Maurin Prof. Dr. Jürgen Senker Dr. Pascal G. Yot Prof. Dr. Norbert Stock 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(17):3877-3883
Herein is reported the utilization of acetonitrile as a new solvent for the synthesis of the three significantly different benchmark metal–organic frameworks (MOFs) CAU-10, Ce-UiO-66, and Al-MIL-53 of idealized composition [Al(OH)(ISO)], [Ce6O4(OH)4(BDC)6], and [Al(OH)(BDC)], respectively (ISO2−: isophthalate, BDC2−: terephthalate). Its use allowed the synthesis of Ce-UiO-66 on a gram scale. While CAU-10 and Ce-UiO-66 exhibit properties similar to those reported elsewhere for these two materials, the obtained Al-MIL-53 shows no structural flexibility upon adsorption of hydrophilic or hydrophobic guest molecules such as water and xenon and is stabilized in its large-pore form over a broad temperature range (130–450 K). The stabilization of the large-pore form of Al-MIL-53 was attributed to a high percentage of noncoordinating −COOH groups as determined by solid-state NMR spectroscopy. The defective material shows an unusually high water uptake of 310 mg g−1 within the range of 0.45 to 0.65 p/p°. In spite of showing no breathing effect upon water adsorption it exhibits distinct mechanical properties. Thus, mercury intrusion porosimetry studies revealed that the solid can be reversibly forced to breathe by applying moderate pressures (≈60 MPa). 相似文献
907.
908.
Stephanie Seel Dr. Guillaume Dagousset Dr. Tobias Thaler Annette Frischmuth Prof. Dr. Konstantin Karaghiosoff Prof. Dr. Hendrik Zipse Prof. Dr. Paul Knochel 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(14):4614-4622
We have developed a practical stereoretentive iodine/lithium‐exchange process that allows the stereodefined preparation of cis‐ and trans‐cycloalkyllithium compounds from their corresponding stereodefined iodides. Quenching with electrophiles offers stereospecific access to both cis‐ (up to 96 % cis) and trans‐cycloalkyl derivatives (up to 99 % trans). A detailed study of the thermodynamic stabilities, stereochemical behavior, and reactivities of axially and equatorially substituted cyclohexyllithium reagents is reported. Ab initio calculations demonstrate that the formation of oligomeric cyclohexyllithium structures is pivotal for explaining the observed stereochemical preference. 相似文献
909.
Anton Buzlukov Guillaume Gerbaud Carole Bourbon Sabine Hediger Gaël De Paëpe Sébastien Patoux Michel Bardet 《Journal of Solid State Electrochemistry》2013,17(5):1421-1427
Different synthesis batches of LiFePO4/C materials were prepared, and their electrochemical properties as positive cathodes for lithium-ion batteries were evaluated. Using standard solid-state NMR conditions, such as a 7-mm magic-angle-spinning probe performing at low spinning rates, information on both intercalated and non-intercalated (stored on the grain boundaries) lithium was obtained. A sharp signal assigned to non-intercalated lithium could be observed by diluting the active material in silica. Correlations could be, thus, obtained between the amount of each type of lithium and the electrochemical history and state of the material, revealing that the relative amount of surface lithium in a pristine LiFePO4/C material is rather constant and cannot be used as a criterion for its further specification. However, a drastic increase of this surface lithium was observed in the cathode materials of out-of-order batteries. As the cathode material recovered from the batteries after electrochemical testing was carefully washed before analysis, we can conclude that the non-intercalated lithium is strongly bound to the active material probably inside the so-called solid electrolyte interface layer at the surfaces of LiFePO4 particles. This work illustrates that solid-state lithium NMR can allow rapid characterization and testing of LiFePO4/C cathode materials. 相似文献
910.
Stphanie Norsikian Cedric Tresse Marc Franois‐Eude Louis Jeanne‐Julien Guillaume Masson Vincent Servajean Grgory Genta‐Jouve Jean‐Marie Beau Emmanuel Roulland 《Angewandte Chemie (International ed. in English)》2020,59(16):6612-6616
A total synthesis of tiacumicin B, a natural macrolide whose remarkable antibiotic properties are used to treat severe intestinal infections, is reported. The strategy is in part based on the prior synthesis of the tiacumicin B aglycone, and on the decisive use of sulfoxides as anomeric leaving groups in hydrogen‐bond‐mediated aglycone delivery (HAD). This new HAD variant permitted highly β‐selective rhamnosylation and noviosylation. To increase convergence, the rhamnosylated C1–C3 fragment thus obtained was anchored to the C4–C19 aglycone fragment by adapting the Suzuki–Miyaura cross‐coupling used for the aglycone synthesis. Ring‐size‐selective macrolactonization provided a compound engaged directly in the noviolysation step with virtually total β selectivity. The final efficient removal of all the protecting groups provided synthetic tiacumicin B. 相似文献