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941.
942.
Nozomi Terada Keisuke Uematsu Ryota Higuchi Dr. Yuki Tokimaru Yosuke Sato Dr. Koji Nakano Prof. Kyoko Nozaki 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(36):9342-9349
A double helicene with a spiro-Si linker ( 4 ) was synthesized by four successive nucleophilic substitutions on SiCl4. Its (P,P), (M,M) and (P,M) isomers were isolated and characterized by single crystal X-ray analysis. Due to the central spirosilabi[fluorene] moiety, the two helicene units in 4 are symmetrically and nearly perpendicularly arranged. (P,P)- 4 and (M,M)- 4 exhibit unique optical properties attributable to the LUMO spiro-conjugation between the two sila[7]helicene units. 相似文献
943.
Journal of Theoretical Probability - We investigate a Belinschi–Nica-type semigroup for free and Boolean max-convolutions. We prove that this semigroup at time one connects limit theorems for... 相似文献
944.
Structure and dynamics of room temperature ionic liquids with bromide anion: results from 81Br NMR spectroscopy
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Takatsugu Endo Mamoru Imanari Yuki Hidaka Hiroko Seki Keiko Nishikawa Sabyasachi Sen 《Magnetic resonance in chemistry : MRC》2015,53(5):369-378
We report the results of a comprehensive 81Br NMR spectroscopic study of the structure and dynamics of two room temperature ionic liquids (RTILs), 1‐butyl‐3‐methylimidazolium bromide ([C4mim]Br) and 1‐butyl‐2,3‐dimethylimidazolium bromide ([C4C1mim]Br), in both liquid and crystalline states. NMR parameters in the gas phase are also simulated for stable ion pairs using quantum chemical calculations. The combination of 81Br spin‐lattice and spin‐spin relaxation measurements in the motionally narrowed region of the stable liquid state provides information on the correlation time of the translational motion of the cation. 81Br quadrupolar coupling constants (CQ) of the two RTILs were estimated to be 6.22 and 6.52 MHz in the crystalline state which were reduced by nearly 50% in the liquid state, although in the gas phase, the values are higher and span the range of 7–53 MHz depending on ion pair structure. The CQ can be correlated with the distance between the cation–anion pairs in all the three states. The 81Br CQ values of the bromide anion in the liquid state indicate the presence of some structural order in these RTILs, the degree of which decreases with increasing temperature. On the other hand, the ionicity of these RTILs is estimated from the combined knowledge of the isotropic chemical shift and the appropriate mean energy of the excited state. [C4C1mim]Br has higher ionicity than [C4mim]Br in the gas phase, while the situation is reverse for the liquid and the crystalline states. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
945.
Cover Picture: Electrochemically Mediated Atom Transfer Radical Polymerization from a Substrate Surface Manipulated by Bipolar Electrolysis: Fabrication of Gradient and Patterned Polymer Brushes (Angew. Chem. Int. Ed. 13/2015)
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946.
Dr. Roman Savka M. Sc. Marvin Bergmann Yuki Kanai Sabine Foro Prof. Dr. Herbert Plenio 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(28):9667-9675
Based on 1‐amino‐4‐hydroxy‐triptycene, new saturated and unsaturated triptycene‐NHC (N‐heterocyclic carbene) ligands were synthesized from glyoxal‐derived diimines. The respective carbenes were converted into metal complexes [(NHC)MX] (M=Cu, Ag, Au; X=Cl, Br) and [(NHC)MCl(cod)] (M=Rh, Ir; cod=1,5‐cyclooctadiene) in good yields. The new azolium salts and metal complexes suffer from limited solubility in common organic solvents. Consequently, the introduction of solubilizing groups (such as 2‐ethylhexyl or 1‐hexyl by O‐alkylation) is essential to render the complexes soluble. The triptycene unit infers special steric properties onto the metal complexes that enable the steric shielding of selected areas close to the metal center. Next, chiral and meso‐triptycene based N‐heterocyclic carbene ligands were prepared. The key step in the synthesis of the chiral ligand is the Buchwald–Hartwig amination of 1‐bromo‐4‐butoxy‐triptycene with (1S,2S)‐1,2‐diphenyl‐1,2‐diaminoethane, followed by cyclization to the azolinium salt with HC(OEt)3. The analogous reaction with meso‐1,2‐diphenyl‐1,2‐diaminoethane provides the respective meso‐azolinium salt. Both the chiral and meso‐azolinium salts were converted into metal complexes including [(NHC)AuCl], [(NHC)RhCl(cod)], [(NHC)IrCl(cod)], and [(NHC)PdCl(allyl)]. An in situ prepared chiral copper complex was tested in the enantioselective borylation of α,β‐unsaturated esters and found to give an excellent enantiomeric ratio (er close to 90:10). 相似文献
947.
948.
949.
Takeshi Yasuda Yuki Shinohara Takaaki Matsuda Liyuan Han Tsutomu Ishi‐i 《Journal of polymer science. Part A, Polymer chemistry》2013,51(12):2536-2544
We synthesized and characterized three new amorphous dithienylbenzothiadiazole (TBT)‐triphenylamine (TPA) polymers for application in bulk‐heterojunction (BHJ) organic photovoltaic (OPV) cells. Poly(3HTBT‐TPA) has hexyl side chains on the thienyl groups (pointing toward the benzothiadiazole (BTD) unit), and poly(4HTBT‐TPA) has hexyl side chains on the thienyl groups (pointing outward from the BTD unit). The incident photon to current conversion efficiencies (IPCEs) in the region from 550 to 650 nm for the OPV cells prepared using poly(4HTBT‐TPA) were higher than those for the OPV cells prepared using poly(3HTBT‐TPA) because the absorption spectrum for the poly(4HTBT‐TPA) has a slightly red‐shifted absorption edge. We also demonstrated that the poly(4HTBT‐TPA)‐based OPV performance is independent of the fabrication process, so using an amorphous film to fabricate BHJ OPV cells offers great advantages over using a polycrystalline film in terms of the high reproducibility of the OPV performance. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 2536–2544 相似文献
950.
Qinghui Li Rina Suzuki Yuki Ono Izumi Nakai Keiichi Tanaka Satoshi Nakayama Haruo Takahashi 《X射线光谱测定》2009,38(5):369-375
Suspended particulate matter (SPM) collected in the urban area of Tokyo was analyzed using a transition edge sensor (TES) microcalorimeter x‐ray detector mounted on a FE‐SEM system. This prototype microcalorimeter spectrometer with an energy resolution of 19 eV identified some severe peak overlaps in the spectra measured by the traditional Si(Li) solid state detector, including S Kα with Pb Mα, Zn Lα with Na Kα, and Ti Kα with Ba Lα. In addition, the TES microcalorimeter showed good spatial resolution for the microanalysis of SPM. The focused ion beam(FIB) was successfully applied to fabricate a cross section of a single SPM particle. The chemical compositonal difference between surface and inner parts, and among different surface parts of the SPM was also determined. Through combination of the FIB technique and the TES microcalorimeter, we achieved a better understanding of the SPM. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献