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191.
Experimental studies of nitrogen adsorbed on a Cu(1 1 1) surface show that the surface layer undergoes a reconstruction to form a pseudo-(1 0 0) structure. We use ab initio techniques to demonstrate the theoretical stability of this reconstructed surface phase over a range of conditions. We systematically investigate the chemisorption of N on the Cu(1 1 1) surface, from 0.06 to 1 ML coverage. A peculiar atomic relaxation of N atoms for 0.75 ML is identified, which results in the formation of a (metastable) “N-trimer cluster” on the surface. We have also investigated surface nitride formation, as suggested from experiments. A surface nitride-like structure similar to the reported pseudo-(1 0 0) reconstruction is found to be highly energetically favored. Using concepts from “ab initio atomistic thermodynamics”, we predict that this surface nitride exists for a narrow range of nitrogen chemical potential before the formation of bulk Cu3N. 相似文献
192.
Dr. Oleg O. Shyshkov Dr. Alexander A. Kolomeitsev Prof. Dr. Berthold Hoge Dr. Enno Lork Dr. Axel Haupt Mira Keßler Prof. Dr. Gerd-Volker Röschenthaler 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(14):e202104308
Phosphoranides are interesting hypervalent species which serve as model compounds for intermediates or transition states in nucleophilic substitution reactions at trivalent phosphorus substrates. Herein, the syntheses and properties of stable trifluoromethylphosphoranide salts are reported. [K(18-crown-6)][P(CF3)4], [K(18-crown-6)][P(CF3)3F], and [NMe4][P(CF3)2F2] were obtained by treatment of trivalent precursors with sources of CF3− or F− units. These [P(CF3)4-nFn]− (n=0–2) salts exhibit fluorinating (n=1–2) or trifluoromethylating (n=0) properties, which is disclosed by studying their reactivity towards selected electrophiles. The solid-state structures of [K(18-crown-6)][P(CF3)4] and [K(18-crown-6)][P(CF3)3F] are ascertained by single crystal X-ray crystallography. The dynamics of these compounds are investigated by variable temperature NMR spectroscopy. 相似文献
193.
194.
Park J Hong S Moon D Park M Lee K Kang S Zou Y John RP Kim GH Lah MS 《Inorganic chemistry》2007,46(24):10208-10213
Discrete metal-organic polyhedra (MOP) with nanosized cavities and/or clusters of MOP could be prepared when C3-symmetric facial ligands and a potential hexatopic Cu(II) ion are combined in the presence of perchlorate as a weak linker, while similar reaction conditions in the presence of a nitrate linker led to extended metal-organic frameworks made of MOP as supramolecular building blocks. 相似文献
195.
An interdigitated 3-D metal-organic framework, [Cd(3)(OH)(2)L(4)(H(2)O)(2)], with 1-D channels was prepared using 4-aminophenyl-1H-tetrazole (HL) and Cd(II) ions, where the host framework shows selective gas sorption behavior that is based on the different nature of the interactions between the gas and the framework rather than on the size-exclusion effect of the micropores. 相似文献
196.
Peschka M Petrovic M Knepper TP Barceló D 《Analytical and bioanalytical chemistry》2007,388(5-6):1227-1234
The transformation products 2-(isopropylcarbamoyl)phenylsulfamic acid and 2-(1-hydroxypropane-2-yl)-1,2-dihydroindazol-3-one
could be determined during the photolysis of the herbicide bentazone. Degradation experiments were carried out with different
types of water in a natural sunlight simulating system. Besides the anticipated hydroxylated bentazone, the second transformation
product was identified by means of exact mass measurement using ultra-performance liquid chromatography/quadrupole time-of-flight
mass spectrometry (UPLC/QqToF MS). Both phototransformation products occurred in all water types tested. The required irradiation
time was matrix dependent. 2-(Isopropylcarbamoyl)phenylsulfamic acid was detected in a drainage channel in the Ebro river
delta (Catalonia, Spain). 相似文献
197.
Much attention has recently been devoted to the life and behaviour of pharmaceuticals in the water cycle. In this study the
behaviour of several pharmaceutical products in different therapeutic categories (analgesics and anti-inflammatory drugs,
lipid regulators, antibiotics, etc.) was monitored during treatment of wastewater in a laboratory-scale membrane bioreactor
(MBR). The results were compared with removal in a conventional activated-sludge (CAS) process in a wastewater-treatment facility.
The performance of an MBR was monitored for approximately two months to investigate the long-term operational stability of
the system and possible effects of solids retention time on the efficiency of removal of target compounds. Pharmaceuticals
were, in general, removed to a greater extent by the MBR integrated system than during the CAS process. For most of the compounds
investigated the performance of MBR treatment was better (removal rates >80%) and effluent concentrations of, e.g., diclofenac,
ketoprofen, ranitidine, gemfibrozil, bezafibrate, pravastatin, and ofloxacin were steadier than for the conventional system.
Occasionally removal efficiency was very similar, and high, for both treatments (e.g. for ibuprofen, naproxen, acetaminophen,
paroxetine, and hydrochlorothiazide). The antiepileptic drug carbamazepine was the most persistent pharmaceutical and it passed
through both the MBR and CAS systems untransformed. Because there was no washout of biomass from the reactor, high-quality
effluent in terms of chemical oxygen demand (COD), ammonium content (N-NH4), total suspended solids (TSS), and total organic carbon (TOC) was obtained. 相似文献
198.
199.
Mira Syahfriena Amir Rawa Nurul Amira Nurul Azman Suriani Mohamad Toshihiko Nogawa Habibah A. Wahab 《Molecules (Basel, Switzerland)》2022,27(9)
Macaranga tanarius (MT) and Syzygium jambos (SJ) are pharmacologically reported to have anti-oxidant, anti-inflammatory, and anti-diabetic effects, and can be neuroprotective agents. Our previous work revealed that MT and SJ exhibited 76.32% and 93.81% inhibition against acetylcholinesterase (AChE) at 50 μg/mL final concentration in their ethyl acetate and hexane fractions, respectively. This study was aimed to investigate the bioactive constituents of MT and SJ and their molecular mechanism toward AChE inhibition. Bioassay-guided isolation afforded prenylflavonoids 1–3 from MT and anacardic acid derivatives 4 and 5 from SJ that were confirmed by NMR and MS data. Compound 5 exerted the strongest anti-AChE potential (IC50: 0.54 μM), followed by 1, 4, 3, and 2 (IC50: 1.0, 2.4, 6.8, and 33 μM, respectively). In silico molecular docking revealed 5 formed stronger molecular interactions including three H-bonds than its derivative 4 based on the saturation of their alkyl chains. The addition of a five carbon-prenyl chain in 1 increased the number of binding interactions, justifying its greater activity than derivatives 2 and 3. This research reflects the first report of AChE inhibitors from these species, thereby adding pharmacological values to MT and SJ as potential remedies in neuroprotection. 相似文献
200.
Shiro Kubuki Koya Shibano Kazuhiko Akiyama Zoltán Homonnay Ernő Kuzmann Mira Ristić Tetsuaki Nishida 《Hyperfine Interactions》2013,218(1-3):47-52
Decomposition mechanism of methylene blue (MB) caused by a mixture of metallic iron-maghemite (Fe0-γFe2O3) was investigated by means of 57Fe-Mössbauer spectroscopy, X-ray diffractometry (XRD), Ultraviolet-Visible Absorption Spectroscopy (UV-vis) and electrospray-ionization mass spectroscopy (ESI-MS). Ten day-leaching test of 10 μmol L???1 MB aqueous solution and Fe0-γFe2O3 mixture (mass ratio 3:7) showed a decrease in the concentration from 10.5 to 4.45 μmol L???1 with first-order rate constant (k) of $1.5_{7} \times 10^{-1}$ day???1. An ESI-MS study of Fe0-γFe2O3 mixture (3:7) after the leaching test revealed new peaks at m/z of 100, 110 and 137 due to fragmentation of MB, in addition to those observed at m/z of 284, 270 and 256 which were ascribed to MB, Azure B and Azure A, respectively. 57Fe-Mössbauer spectra of Fe0-γFe2O3 mixture (3:7) resulted in a decrease in absorption area (A) for Fe0 (δ?=?0.00±0.01 mm s???1, H int?=?33.0±0.1 T) from 37.5 to 21.3, 9.7, 7.9, 7.0 and 4.5±0.5 %, together with an increase in A from 0.0 to 5.0, 13.8, 17.2, 21.0 and 22.4±0.5 % for octahedral (O h) iron (FeII?+?FeIII) of Fe3O4. XRD study of these samples indicated that the peak intensity at 2Θ of 44.7° being ascribed to Fe0 was decreased, while that of 35.6° due to Fe3O4 was almost constant; relative peak ratio of Fe $^{0}/\mathrm{Fe}_{3}$ O4 was decreased from 26.3 to 2.76 after the leaching, indicating that Fe0 in the Fe0-γFe2O3 mixture was oxidized to Fe3O4. These experimental results suggest that Fe0-γFe2O3 mixture could be utilized for the cleaning or decomposition of toxic organic compounds like trichloroethylene. 相似文献