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991.
A new ground triplet biradical 2′,4′,6′-triisopropylbiphenyl-3,5-diyl bis(tert-butyl nitroxide) (iPr3BPBN) was prepared and characterized by means of room-temperature ESR spectroscopy displaying a zero-field splitting pattern together with a half-field signal. Complex formation with gadolinium(III) 1,1,1,5,5,5-hexafluoropentane-2,4-dionate (hfac) afforded a macrocycle [{Gd(hfac)3(μ-iPr3BPBN)}2]. As the X-ray crystallographic analysis clarified, the biradical serves as a bridging ligand, giving a 16-membered ring, where each nitroxide radical oxygen atom is directly bonded to a Gd3+ ion. The magnetic study revealed that the iPr3BPBN bridge behaved as a practically triplet biradical and that the Gd3+-radical magnetic coupling was weakly ferromagnetic. The exchange parameters were estimated as 2jrad-rad/kB > 300 K and 2JGd-rad/kB = 1.2 K in the H = −2J S1•S2 convention. The DFT calculation based on the atomic coordinates clarified the ground triplet nature in metal-free iPr3BPBN and the enhanced triplet character upon coordination. The calculation also suggests that ferromagnetic coupling would be favorable when the Gd-O-N-C(sp2) torsion comes around 100°. The present results are compatible with the proposed magneto-structure relationship on the nitroxide-Gd compounds. 相似文献
992.
Xiaoqian Wei Shaojia Song Weiyu Song Yating Wen Weiqing Xu Yifeng Chen Zhichao Wu Ying Qin Lei Jiao Yu Wu Meng Sha Jiajia Huang Xiaoli Cai Lirong Zheng Liuyong Hu Wenling Gu Miharu Eguchi Toru Asahi Yusuke Yamauchi Chengzhou Zhu 《Chemical science》2022,13(45):13574
The large-scale application of nanozymes remains a significant challenge owing to their unsatisfactory catalytic performances. Featuring a unique electronic structure and coordination environment, single-atom nanozymes provide great opportunities to vividly mimic the specific metal catalytic center of natural enzymes and achieve superior enzyme-like activity. In this study, the spin state engineering of Fe single-atom nanozymes (FeNC) is employed to enhance their peroxidase-like activity. Pd nanoclusters (PdNC) are introduced into FeNC, whose electron-withdrawing properties rearrange the spin electron occupation in Fe(ii) of FeNC–PdNC from low spin to medium spin, facilitating the heterolysis of H2O2 and timely desorption of H2O. The spin-rearranged FeNC–PdNC exhibits greater H2O2 activation activity and rapid reaction kinetics compared to those of FeNC. As a proof of concept, FeNC–PdNC is used in the immunosorbent assay for the colorimetric detection of prostate-specific antigen and achieves an ultralow detection limit of 0.38 pg mL−1. Our spin-state engineering strategy provides a fundamental understanding of the catalytic mechanism of nanozymes and facilitates the design of advanced enzyme mimics.Spin-state engineering was proposed to enhance the peroxidase-like activity of single-atom nanozymes through the electron-withdrawing properties of Pd nanoclusters, which facilitates the heterolysis process of H2O2 and the desorption of H2O. 相似文献
993.
Le Xu Madhuresh K. Choudhary Koki Muraoka Watcharop Chaikittisilp Toru Wakihara Jeffrey D. Rimer Tatsuya Okubo 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(41):14671-14675
There is broad scientific interest in lamellar zeolitic materials for a large variety of technological applications. The traditional synthetic methods towards two‐dimensional (2D) zeolitic precursors have made a great impact in the construction of families of related zeolites; however, the connection between structurally distinct 2D zeolitic precursors is much less investigated in comparison, thereby resulting in a synthetic obstacle that theoretically limits the types of zeolites that can be constructed from each layer. Herein, we report a Ge‐recycling strategy for the topotactic conversion between different 2D zeolitic precursors through a three‐dimensional (3D) germanosilicate. Specifically, the intermediate germanosilicate can be constructed within 150 min by taking advantage of its structural similarity with the parent lamellar precursor. This process enables the conversion of one 2D zeolite structure into another distinct structure, thus overcoming the synthetic obstacle between two families of zeolitic materials. 相似文献
994.
Koshi Nagai Baasanjav Uranbileg Zhen Chen Amane Fujioka Takahiro Yamazaki Yotaro Matsumoto Hiroki Tsukamoto Hitoshi Ikeda Yutaka Yatomi Hitoshi Chiba Shu‐Ping Hui Toru Nakazawa Ritsumi Saito Seizo Koshiba Junken Aoki Daisuke Saigusa Yoshihisa Tomioka 《Rapid communications in mass spectrometry : RCM》2020,34(Z1)
995.
Tetsuya TAKAHASHI Michitaka KATO Kengo OBATA Ryo KOZU Toru FUJIMOTO Koji YAMASHITA Morihide ANDO Yusuke KAWAI Noriaki KOJIMA Hiroshi KOMATSU Kensuke NAKAMURA Yuhei YAMASHITA Shane PATMAN Akemi UTSUNOMIYA Osamu NISHIDA 《Physical Therapy Research》2021,24(1):52
Objective: Early mobilization and rehabilitation has become common and expectations for physical therapists working in intensive care units have increased in Japan. The objective of this study was to establish consensus-based minimum clinical practice standards for physical therapists working in intensive care units in Japan. It also aimed to make an international comparison of minimum clinical practice standards in this area. Methods: In total, 54 experienced physical therapists gave informed consent and participated in this study. A modified Delphi method with questionnaires was used over three rounds. Participants rated 272 items as “essential/unknown/non-essential”. Consensus was considered to be reached on items that over 70% of physical therapists rated as “essential” to clinical practice in the intensive care unit. Results: Of the 272 items in the first round, 188 were deemed essential. In round 2, 11 of the 62 items that failed to reach consensus in round 1 were additionally deemed essential. No item was added to the “essential” consensus in round 3. In total, 199 items were therefore deemed essential as a minimum standard of clinical practice. Participants agreed that 42 items were not essential and failed to reach agreement on 31 others. Identified 199 items were different from those in the UK and Australia due to national laws, cultural and historical backgrounds. Conclusions: This is the first study to develop a consensus-based minimum clinical practice standard for physical therapists working in intensive care units in Japan. 相似文献
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999.
A preliminary study of isopropanol (IPA) adsorption/desorption isotherms on a jungle-gym-type porous coordination polymer, [Zn(2)(bdc)(2)(dabco)](n) (1, H(2)bdc = 1,4-benzenedicarboxylic acid, dabco =1,4-diazabicyclo[2.2.2]octane), showed unambiguous two-step profiles via a highly shrunk intermediate framework. The results of adsorption measurements on 1, using probing gas molecules of alcohol (MeOH and EtOH) for the size effect and Me(2)CO for the influence of hydrogen bonding, show that alcohol adsorption isotherms are gradual two-step profiles, whereas the Me(2)CO isotherm is a typical type-I isotherm, indicating that a two-step adsorption/desorption is involved with hydrogen bonds. To further clarify these characteristic adsorption/desorption behaviors, selecting nitroterephthalate (bdc-NO(2)), bromoterephthalate (bdc-Br), and 2,5-dichloroterephthalate (bdc-Cl(2)) as substituted dicarboxylate ligands, isomorphous jungle-gym-type porous coordination polymers, {[Zn(2)(bdc-NO(2))(2)(dabco)]·solvents}(n) (2 ? solvents), {[Zn(2)(bdc-Br)(2)(dabco)]·solvents}(n) (3 ? solvents), and {[Zn(2)(bdc-Cl(2))(2)(dabco)]·solvents}(n) (4 ? solvents), were synthesized and characterized by single-crystal X-ray analyses. Thermal gravimetry, X-ray powder diffraction, and N(2) adsorption at 77 K measurements reveal that [Zn(2)(bdc-NO(2))(2)(dabco)](n) (2), [Zn(2)(bdc-Br)(2)(dabco)](n) (3), and [Zn(2)(bdc-Cl(2))(2)(dabco)](n) (4) maintain their frameworks without guest molecules with Brunauer-Emmett-Teller (BET) surface areas of 1568 (2), 1292 (3), and 1216 (4) m(2) g(-1). As found in results of MeOH, EtOH, IPA, and Me(2)CO adsorption/desorption on 2-4, only MeOH adsorption on 2 shows an obvious two-step profile. Considering the substituent effects and adsorbate sizes, the hydrogen bonds, which are triggers for two-step adsorption, are formed between adsorbates and carboxylate groups at the corners in the pores, inducing wide pores to become narrow pores. Interestingly, such a two-step MeOH adsorption on 2 depends on the temperature, attributed to the small free-energy difference (ΔF(host)) between the two guest-free forms, wide and narrow pores. 相似文献
1000.
Haruya Inuzuka Daisuke Urushihara Toru Asaka 《Journal of solid state chemistry》2010,183(11):2570-2575
A new aluminum oxycarbonitride, Al5(OxCyN4−x−y) (x∼1.4 and y∼2.1), has been synthesized and characterized by X-ray powder diffraction, transmission electron microscopy and electron energy loss spectroscopy (EELS). The title compound was found to be hexagonal with space group P63/mmc, Z=2, and unit-cell dimensions a=0.328455(6) nm, c=2.15998(3) nm and V=0.201805(6) nm3. The atom ratios O:C:N were determined by EELS. The final structural model, which is isomorphous with that of (Al4.4Si0.6)(O1.0C3.0), showed the positional disordering of one of the three types of Al sites. The maximum-entropy method-based pattern fitting (MPF) method was used to confirm the validity of the split-atom model, in which conventional structure bias caused by assuming intensity partitioning was minimized. The reliability indices calculated from the MPF were Rwp=6.94% (S=1.22), Rp=5.34%, RB=1.35% and RF=0.76%. The crystal was an inversion twin. Each twin-related individual was isostructural with Al5C3N (space group P63mc, Z=2). 相似文献