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61.
Kallol K. Ghosh Sunita Bal Manmohan L. Satnami P. Rodriguez‐Dafonte Rama M. Palepu 《Journal of Dispersion Science and Technology》2013,34(3):349-355
Pseudo‐first‐order rate constants have been determined for the nucleophilic substitution reactions of p‐nitrophenyl acetate with oxalo, malono, and succinodihydroxamate ions (?ONHC(O)(CH2)nC(O)NHO?) in phosphate buffer (pH=7.9) at 27°C. The rate data of the reaction revealed that the nucleophilic reactivity sequence of these hydroxamate ions is generally ODHA>MDHA>SDHA. The kobs value increases upon addition of cationic surfactants to the reaction medium which is typical behavior of micelle‐assisted bimolecular reactions. The pseudo‐phase ion exchange model has been successfully applied to determine binding constant. 相似文献
62.
J. M. Vega Pérez C. Gómez Herrera F. J. Ruiz Rodriguez M. B. Riego Martín 《Journal of Dispersion Science and Technology》2013,34(3):259-269
The synthesis and identification of this product are described. Variations of surface tension of its aqueous solutions versus concentration (ranged between 3 and 95 mmol/L) and temperature (ranged between 20.0 and 47.5°C) are studied. The isothermal plots of surface tension versus the logarithm of the concentration show a continous decrease, with a sharp change of slope at a concentration about 6.5 mmol/L, for all the studied temperatures. A second change of slope, less pronounced, appears for a higher concentration. This concentration value increases from 28 to 42 mmol/L when temperature is raised from 20.0 to 47.5°C. The changes of slope can be attributed mainly to micellization of neutral amine molecules resulting from hydrolysis of surface active cations, which present a weak electrolytic character. 相似文献
63.
Isoflavonoids are a class of organic compounds that act primarily as antioxidants. They are produced almost exclusively by various members of the bean family including soybeans, tofu, peanuts, chick peas, and alfalfa. The antioxidant characteristics that isoflavonoids exhibit help hinder the progression of certain cancers, primarily breast, prostate, and colon cancer. We have developed a three-five step synthesis for obtaining a suite of isoflavonoid derivatives. The synthesis involves an enamine formation, a ring closure and halogenation, a Suzuki coupling, and finally a global deprotection to obtain the respective isoflavonoid derivatives. 相似文献
64.
Marcio David Bocelli Deyber Arley Vargas Medina Julie Paulin García Rodriguez Fernando Mauro Lanças Álvaro José Santos-Neto 《Electrophoresis》2022,43(15):1567-1576
Dynamic single-drop microextraction (SDME) was automatized employing an Arduino-based lab-made Cartesian robot and implemented to determine parabens in wastewater samples in combination with liquid chromatography–tandem mass spectrometry. A dedicated Arduino sketch controls the auto-performance of all the stages of the SDME process, including syringe filling, drop exposition, solvent recycling, and extract collection. Univariate and multivariate experiments investigated the main variables affecting the SDME performance, including robot-dependent and additional operational parameters. Under selected conditions, limit of detections were established at 0.3 µg/L for all the analytes, and the method provided linear responses in the range between 0.6 and 10 µg/L, with adequate reproducibility, measured as intraday relative standard deviations (RSDs) between 5.54% and 17.94%, (n = 6), and inter-days RSDs between 8.97% and 16.49% (n = 9). The robot-assisted technique eased the control of dynamic SDME, making the process more feasible, robust, and reliable so that the developed setup demonstrated to be a competitive strategy for the automated extraction of organic pollutants from water samples. 相似文献
65.
Ch. Jesús F. Socorro H. J. Rodriguez de Rivera M. Rodriguez de Rivera 《Journal of Thermal Analysis and Calorimetry》2014,116(1):151-155
A calorimetric sensor has been developed for local and direct measurement of calorific dissipations in different parts of the human body. The constructed prototype has a detection surface of 36 cm2. In this paper, a deconvolution method is proposed to reconstruct the dissipated power. The advantage of this method is that: to determine the dissipated power, it is not necessary to correct the baselines to calculate either the areas of the calorimetric signal or that of the dissipated power in the temperature control because the proposed method takes into account, apart from the calorimetric signal, the thermostat temperature and the ambient temperature. 相似文献
66.
Prof. Dr. Wolfram Sander Dr. Saonli Roy Kenny Bravo‐Rodriguez Dr. Dirk Grote Dr. Elsa Sanchez‐Garcia 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(40):12917-12923
The benzyl radical ( 1 ) is a key intermediate in the combustion and tropospheric oxidation of toluene. Because of its relevance, the reaction of 1 with molecular oxygen was investigated by matrix‐isolation IR and EPR spectroscopy as well as computational methods. The primary reaction product of 1 and O2 is the benzylperoxyl radical ( 2 ), which exists in several conformers that can easily interconvert even at cryogenic temperatures. Photolysis of radical 2 at 365 nm results in a formal [1,3]‐H migration and subsequent cleavage of the O?O bond to produce a hydrogen‐bonded complex between the hydroxyl radical and benzaldehyde ( 4 ). Prolonged photolysis produces the benzoyl radical ( 5 ) and water, which finally yield the phenyl radical ( 7 ), CO, and H2O. Thus, via a sequence of exothermic reactions 1 is transformed into radicals of even higher reactivity, such as OH and 7 . Our results have implications for the development of models for the highly complicated process of combustion of aromatic compounds. 相似文献
67.
Suihan Feng Dr. Vibor Laketa Frank Stein Dr. Anna Rutkowska Dr. Aidan MacNamara Dr. Sofia Depner Prof. Ursula Klingmüller Dr. Julio Saez‐Rodriguez Priv.‐Doz. Dr. Carsten Schultz 《Angewandte Chemie (International ed. in English)》2014,53(26):6720-6723
Chemical dimerizers are powerful tools for non‐invasive manipulation of enzyme activities in intact cells. Here we introduce the first rapidly reversible small‐molecule‐based dimerization system and demonstrate a sufficiently fast switch‐off to determine kinetics of lipid metabolizing enzymes in living cells. We applied this new method to induce and stop phosphatidylinositol 3‐kinase (PI3K) activity, allowing us to quantitatively measure the turnover of phosphatidylinositol 3,4,5‐trisphosphate (PIP3) and its downstream effectors by confocal fluorescence microscopy as well as standard biochemical methods. 相似文献
68.
Patrick J. Whitham Dennis P. Strommen Sandra Lundell Lisa D. Lau Rene Rodriguez 《Plasma Chemistry and Plasma Processing》2014,34(4):755-766
The plasma enhanced chemical vapor depositions of germanium chalcogenide thin films from germanium tetrachloride, hydrogen sulfide and alkyl chalcogenides were studied to determine the viability of these reagents for thin film deposition. Hydrogen sulfide is a commonly used reagent for this technique and was used to determine optimal reaction conditions for thin film deposition. Germanium tetrachloride, alkylsulfides and alkylselenides were also employed because of their lower potential toxicities and higher availabilities compared to their more typical congeners: germane, hydrogen sulfide and hydrogen selenide in the formation of germanium chalcogenides. Alkylsulfides were found to be unsuitable for the deposition of germanium sulfides, however alkylselenide precursors were used successfully for the deposition of germanium selenides. The relative mass flow rates, reactor pressure, substrate temperature and plasma power density were studied for their effects on germanium chalcogenide deposition. These parameters affected the composition, deposition rate, film quality, and spectroscopic properties of the deposited films. 相似文献
69.
Dr. Jessica Rodriguez Dr. György Szalóki Dr. E. Daiann Sosa Carrizo Dr. Nathalie Saffon-Merceron Dr. Karinne Miqueu Dr. Didier Bourissou 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(4):1527-1531
Gold(III) π-complexes have been authenticated recently with alkenes, alkynes, and arenes. The key importance of PdII π-allyl complexes in organometallic chemistry (Tsuji–Trost reaction) prompted us to explore gold(III) π-allyl complexes, which have remained elusive so far. The (P,C)AuIII(allyl) and (methallyl) complexes 3 and 3′ were readily prepared and isolated as thermally and air-stable solids. Spectroscopic and crystallographic analyses combined with detailed DFT calculations support tight quasi-symmetric η3-coordination of the allyl moiety. The π-allyl gold(III) complexes are activated towards nucleophilic additions, as substantiated with β-diketo enolates. 相似文献
70.
Stabilization of Catalytically Active Cu+ Surface Sites on Titanium–Copper Mixed‐Oxide Films 下载免费PDF全文
Dr. Ashleigh E. Baber Dr. Xiaofang Yang Dr. Hyun You Kim Dr. Kumudu Mudiyanselage Markus Soldemo Dr. Jonas Weissenrieder Dr. Sanjaya D. Senanayake Dr. Abdullah Al‐Mahboob Dr. Jerzy T. Sadowski Dr. Jaime Evans Dr. José A. Rodriguez Dr. Ping Liu Dr. Friedrich M. Hoffmann Dr. Jingguang G. Chen Dr. Darío J. Stacchiola 《Angewandte Chemie (International ed. in English)》2014,53(21):5336-5340
The oxidation of CO is the archetypal heterogeneous catalytic reaction and plays a central role in the advancement of fundamental studies, the control of automobile emissions, and industrial oxidation reactions. Copper‐based catalysts were the first catalysts that were reported to enable the oxidation of CO at room temperature, but a lack of stability at the elevated reaction temperatures that are used in automobile catalytic converters, in particular the loss of the most reactive Cu+ cations, leads to their deactivation. Using a combined experimental and theoretical approach, it is shown how the incorporation of titanium cations in a Cu2O film leads to the formation of a stable mixed‐metal oxide with a Cu+ terminated surface that is highly active for CO oxidation. 相似文献