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41.
A remarkable effect of ionic liquids in transition-metal-free aerobic oxidation of benzylic alcohols
Yoshiro OdaKoji Hirano Tetsuya SatohSusumu Kuwabata Masahiro Miura 《Tetrahedron letters》2011,52(41):5392-5394
The transition-metal-free aerobic oxidation of benzylic alcohols is uniquely accelerated by a 1-butyl-3-methylimidazolium hexafluorophosphate (BMI-PF6)/PhCF3 biphasic system and Cs2CO3 to afford the corresponding ketones in good yields. The reaction system is also applicable to an oxidative cross-esterification of primary benzyl alcohols with a higher aliphatic alcohol. 相似文献
42.
Shinya Hayami Yasuka Komatsu Tetsuya Shimizu Hidenobu Kamihata Young Hoon Lee 《Coordination chemistry reviews》2011,255(17-18):1981-1990
In this review article we discuss the unique and novel magnetic properties for the cobalt(II) compounds with a variety of terpy derivatives including substituents at the 4-position. These are also compared with the unsubstituted terpy cobalt(II) complex. Since the first SCO cobalt(II) complex with terpy ligand was reported, this system has been widely studied. SCO cobalt(II) complexes possessing terpy or OH-terpy ligand reveal incomplete or gradual SCO behavior. The pyterpy-appended cobalt(II) complex shows SCO depending on the guest molecules involved. Cobalt(II) complexes with long-alkylated terpy ligands, [Co(Cn-terpy)2](BF4)2 (n = 16, 14 and 12) have been synthesized and some were characterized by single crystal X-ray analysis. Furthermore, variable-temperature magnetic susceptibility indicated that the non-solvated compounds [Co(Cn-terpy)2](BF4)2 (n = 16, 14 and 12) exhibit “reverse spin transition” phenomenon with wide thermal hysteresis around room temperature. In addition, the solvated compound [Co(C12-terpy)2](BF4)2·EtOH·0.5H2O shows “re-entrant SCO” behavior. The long alkyl chains in SCO cobalt(II) complexes can lead to novel physical properties resulting from a synergetic effect between SCO and response of the flexibility toward external stimuli. 相似文献
43.
Masafumi UedaYuki Ikeda Aoi SatoYuta Ito Maiko KakiuchiHiroko Shono Tetsuya MiyoshiTakeaki Naito Okiko Miyata 《Tetrahedron》2011,67(25):4612-4615
A facile and practical synthesis of 3,5-disubstituted isoxazoles via a silver-catalyzed cyclization and subsequent protonation of alkynyl oxime ethers has been developed. The methodology was successfully applied to the synthesis of a biologically active isoxazolecarboxylic acid. 相似文献
44.
Tetsuya Shimizu Yasuka Komatsu Hidenobu Kamihata Young Hoon Lee Akira Fuyuhiro Seiichiro Iijima Shinya Hayami 《Journal of inclusion phenomena and macrocyclic chemistry》2011,71(3-4):363-369
Iron(III) spin-crossover compounds, [Fe(qnal)2]CF3SO3·MeOH (1·MeOH) and [Fe(qnal)2]CF3SO3·acetone (1·acetone) were prepared and their spin transition properties were characterized by magnetic susceptibility measurement, Mössbauer spectroscopy and single crystal analysis. Two iron(III) compounds exhibited abrupt spin transition with thermal hysteresis loop (T 1/2?? = 115 K and T 1/2?? = 104 K for 1·MeOH, and T 1/2?? = 133 K and T 1/2?? = 130 K for 1·acetone). Single crystal analysis revealed both of the structures in high-spin (HS) and low-spin (LS) states for 1·acetone. The difference of bond length between the HS and LS states for 1·acetone was ~0.10 Å, which was corresponding to that of typical iron(III) SCO compounds. Specially, it showed strong intermolecular interactions by ???C?? stacking formed between the neighbor complexes leading to 2-D sheet. Both 1·MeOH and 1·acetone exhibited LIESST effect when it was illuminated at 1000 nm. We also confirmed that the introduction of strong intermolecular interactions, such as ???C?? stacking, can play an important role in LIESST effect. 相似文献
45.
Multiple Reaction Pathways Operating in the Mechanism of Vinylogous Mannich‐Type Reaction Activated by a Water Molecule 下载免费PDF全文
A systematic search for reaction pathways for the vinylogous Mannich‐type reaction was performed by the artificial force induced reaction method. This reaction affords δ‐amino‐γ‐butenolide in one pot by mixing 2‐trimethylsiloxyfuran, imine, and water under solvent‐free conditions. Surprisingly, the search identified as many as five working pathways. Among them, two concertedly produce anti and syn isomers of the product. Another two give an intermediate, which is a regioisomer of the main product. This intermediate can undergo a retro‐Mannich reaction to give a pair of intermediates: an imine and 2‐furanol. The remaining pathway directly generates this intermediate pair. The imine and 2‐furanol easily react with each other to afford the product. Thus, all of these stepwise pathways finally converge to give the main product. The rate‐determining step of all five (two concerted and three stepwise) pathways have a common mechanism: concerted Si? O bond formation through the nucleophilic attack of a water molecule on the silicon atom followed by proton transfer from the water molecule to the imine. Therefore, these five pathways have comparable barriers and compete with each other. 相似文献
46.
Synergistic Spin Transition between Spin Crossover and Spin‐Peierls‐like Singlet Formation in the Halogen‐Bonded Molecular Hybrid System: [Fe(Iqsal)2][Ni(dmit)2]⋅CH3CN⋅H2O 下载免费PDF全文
Kappei Fukuroi Prof. Dr. Kazuyuki Takahashi Prof. Dr. Tomoyuki Mochida Dr. Takahiro Sakurai Prof. Dr. Hitoshi Ohta Dr. Takashi Yamamoto Prof. Dr. Yasuaki Einaga Prof. Dr. Hatsumi Mori 《Angewandte Chemie (International ed. in English)》2014,53(7):1983-1986
To introduce halogen‐bond interactions between a cation and an anion, a novel FeIII complex from iodine‐substituted ligands involving a paramagnetic nickel dithiolene anion was prepared and characterized. The compound exhibited the synergy between a spin‐crossover transition and a spin‐Peierls‐like singlet formation. The halogen‐bond interactions between the iodine and the sulfur atoms stabilized the paramagnetic state of π‐spins and played a crucial role in the synergistic magnetic transition between d‐ and π‐spins. In addition, the compound showed the light‐induced excited spin state trapping effect. 相似文献
47.
Total Synthesis of the Antibiotic Kendomycin: A Macrocyclization Using the Tsuji–Trost Etherification 下载免费PDF全文
Dr. Tetsuya Sengoku Dr. Shu Xu Kenji Ogura Yoshinori Emori Kenji Kitada Prof. Dr. Daisuke Uemura Prof. Dr. Hirokazu Arimoto 《Angewandte Chemie (International ed. in English)》2014,53(16):4213-4216
A highly stereocontrolled, convergent total synthesis of kendomycin [(?)‐TAN2162], an ansa‐macrocyclic antibiotic, is reported. The key of the strategy is an unprecedented Tsuji–Trost macrocyclic etherification, followed by a transannular Claisen rearrangement to construct the 18‐membered carbocyclic framework. The oxa‐six‐ and five‐membered rings were also stereoselectively constructed respectively by a cascade oxidative cyclization at an unfunctionalized benzylic position and using a one‐pot epoxidation/5‐exo‐tet epoxide opening. 相似文献
48.
Yasunori Fujikoshi Tamio Kan Shin Takahashi Tetsuro Sakurai 《Annals of the Institute of Statistical Mathematics》2011,63(2):387-403
Several criteria, such as CV, C
p
, AIC, CAIC, and MAIC, are used for selecting variables in linear regression models. It might be noted that C
p
has been proposed as an estimator of the expected standardized prediction error, although the target risk function of CV
might be regarded as the expected prediction error R
PE. On the other hand, the target risk function of AIC, CAIC, and MAIC is the expected log-predictive likelihood. In this paper,
we propose a prediction error criterion, PE, which is an estimator of the expected prediction error R
PE. Consequently, it is also a competitor of CV. Results of this study show that PE is an unbiased estimator when the true model
is contained in the full model. The property is shown without the assumption of normality. In fact, PE is demonstrated as
more faithful for its risk function than CV. The prediction error criterion PE is extended to the multivariate case. Furthermore,
using simulations, we examine some peculiarities of all these criteria. 相似文献
49.
This paper investigates the flow field near three intersecting shock waves appearing in steady Mach reflection. Results of
numerical computations reveal a “von Neumann Paradox”—like feature for weak shock waves, in which the flow field between the
reflected and the Mach stem is smooth with no distinct slip flow region and changes rather smoothly. An analytical solution
of the Navier–Stokes equations constructed using a polar–coordinate system gives a flow field with the same properties as
the numerical simulation. 相似文献
50.
A rhodium(III)‐catalyzed redox‐neutral coupling of α‐trifluoromethylacrylic acid with bezamides proceeds smoothly accompanied by amide‐directed C?H bond cleavage to produce β‐[2‐(aminocarbonyl)phenyl]‐α‐trifluoromethylpropanoic acid derivatives. One of the products can be transformed to a trifluoromethyl substituted heterocyclic compound. In addition, the redox‐neutral coupling of α‐trifluoromethylacrylic acid with related aromatic substrates possessing a nitrogen‐containing directing group can also be conducted under similar conditions. 相似文献