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71.
The eigenvalue analysis of rolling tires is one part of the simulation of tire rolling noise radiation for the reduction of traffic noise. In this paper the general strategies of numerical eigenvalue analysis for nonsymmetric matrices are shown. The special effects observed on rotating bodies are discussed in details. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
72.
Gudrun Schürer Peter Gedeck Maik Gottschalk Timothy Clark 《International journal of quantum chemistry》1999,75(1):17-31
The variational method for the calculation of the electronic polarizability of molecules within the NDDO‐based semiempirical MO methods MNDO, AM1, and PM3 was parametrized to improve its accuracy. A training set of 156 compounds was used to fit 34 parameters simultaneously for 12 elements using a simplex optimization. The resulting parameters were tested for a test set of 83 molecules and the calculated polarizabilities compared with the experimental data. For AM1, the RMS deviation between experimental and calculated polarizabilities was reduced from 2.99 (using the original variational treatment) to 0.70 Å3 for the test set and from 2.81 to 0.40 Å3 for the training set. MNDO and PM3 gave similar improvements. ©1999 John Wiley & Sons, Inc. Int J Quant Chem 75: 17–31, 1999 相似文献
73.
Olayide S. Lawal Jörg Storz Derek Lohmann Werner-Michael Kulicke 《European Polymer Journal》2009,45(12):3399-3408
Carboxymethyl cassava starch (CMS) was synthesized and its hydrogels were prepared by cross-linking it with di- or polyfunctional carboxylic acids using glutaric (CASXGLU), suberic (CASXSUB), pimelic (CASXPIM) and butanetetracarboxylic acids (CASBTC) as the cross-linkers. The characterization of the CMS showed that its degree of substitution was 0.86, average molar mass (Mw) was 5.6 × 106 g mol−1 and the 13C NMR showed strong peak at δ = 180.42 ppm which was assigned to the CO carbon in the carboxymethyl group. The absorption under load (AUL) and free swelling capacity (FSC) studies showed that the hydrogels have fast swelling properties and that they reached equilibrium after 1 h. Furthermore, all the hydrogels were sensitive to the increasing salt concentrations and pH of the medium. Both AUL and FSC reduced in saline solution while their values increased in alkaline buffer solutions. The result indicate that the difunctional carboxylic acids produced hydrogels with stronger material functions compared with the polyfunctional carboxylic acid and the order of increases in both AUL and FSC was CASXBTC, CASXPIM, CASXSUB and CASXGLU. 相似文献
74.
The metabolism of the selective estrogen receptor modulator toremifene was simulated in an on-line electrochemistry/enzyme
reactor/liquid chromatography/mass spectrometry system. To simulate the oxidative phase I metabolism, toremifene was oxidized
in an electrochemical (EC) flow-through cell at 1,500 mV vs. Pd/H2 to its phase I metabolites, some of which are reactive quinoid species. In the presence of glutathione-S-transferase (GST), these quinoid compounds react with glutathione, which is also the common detoxification mechanism in the
body. While reacting with glutathione, the chlorine atom is eliminated from the toremifene moiety. Due to higher conversion
rates, GST supplied in continuous flow proved to be more efficient than using immobilized GST on magnetic microparticles.
In the absence of GST, not all GSH adducts are formed, proving the necessity of a phase II enzyme to simulate the complete
metabolic pathway of xenobiotics in an on-line EC/LC/MS system.
Figure Mass voltammogram of toremifene 相似文献
75.
Point-of-care testing (POCT) in patients with ischemic heart disease is driven by the time-critical need for fast, specific,
and accurate results to initiate therapy instantly. According to current guidelines, the results of the cardiac marker testing
should be available to the physician within 30 min (“vein-to-brain” time) to initiate therapy within 60–90 min (“door-to-needle”
time) after the patient has arrived at the emergency room or intensive care unit. This article reviews the current efforts
to meet this goal (1) by implementing POCT of established biochemical markers such as cardiac troponins, creatine kinase MB,
and myoglobin, in accelerated diagnosis and management workflow schemes, (2) by improving current POCT methods to obtain more
accurate, more specific, and even faster tests through the integration of optical and electrochemical sensor technology, and
(3) by identifying new markers for the very early and sensitive detection of myocardial ischemia and necrosis. Furthermore,
the specific requirements for cardiac POCT in regard to analytical performance, comparability, and diagnostic sensitivity/specificity
are discussed. For the future, the integration of new immunooptical and electrochemical chip technology might speed up diagnosis
even further. However, every new development will have to meet the stringent method validation criteria set for corresponding
central laboratory testing. 相似文献
76.
Reactions of tris(trifluoromethyl)borane carbonyl, (CF(3))(3)BCO, with ammonia yielded either a mixture of [NH(4)][(CF(3))(3)BC(O)NH(2)], [NH(4)][(CF(3))(3)BCN], and [NH(4)](2)[{(CF(3))(3)BC(O)}(2)NH] or neat [NH(4)](2)[{(CF(3))(3)BC(O)}(2)NH] depending on the reaction conditions. The salt K[(CF(3))(3)BC(O)NH(2)] was obtained as the sole product from the reaction of NH(3) with K[(CF(3))(3)BC(O)F]. A simple synthesis for cyanotris(trifluoromethyl)borates, M[(CF(3))(3)BCN], was developed by dehydration of M[(CF(3))(3)BC(O)NH(2)] (M = [NH(4)], K) using phosgene. In addition, syntheses of the tris(trifluoromethyl)boron species [(CF(3))(3)BC(O)NH(n)()Pr](-), [(CF(3))(3)BC(O)NMe(2)](-), and (CF(3))(3)BC(O)NMe(3), as well as of (CF(3))(3)BC(O)PMe(3), were performed. All species were characterized by multinuclear NMR spectroscopy. As far as neat substances resulted, IR and Raman spectra were recorded and their thermal behaviors were studied by differential scanning calorimetry. The interpretation of reaction pathways, structures, and vibrational spectra are supported by DFT calculations. The solid-state structure of K(2)[{(CF(3))(3)BC(O)}(2)NH].2MeCN was determined by single-crystal X-ray diffraction. 相似文献
77.
A high-power longitudinally pumped Nd:YAG laser using direct pumping into the upper laser level is demonstrated. With an absorbed pump power of 438 W an output power of 250 W was realized, which results in an optical-to-optical efficiency of 57%. To the best of our knowledge, this is the first demonstration of a high-output power 885 nm pumped laser design. 相似文献
78.
Jahn S Lohmann W Bomke S Baumann A Karst U 《Analytical and bioanalytical chemistry》2012,402(1):461-471
In the present study, a method for the analysis of reactive metabolites via liquid chromatography (LC) with inductively coupled
plasma–mass spectrometry (MS) was developed. A ferrocenyl-modified glutathione (GSH) reagent, consisting of GSH and succinimidyl-3-ferrocenylpropionate,
was synthesized. Derivatization of the tripeptide was performed at the N-terminus, leaving the nucleophilic thiol group vacant
for the attack of electrophilic compounds. The potential of ferrocenylpropionate (FP)-GSH as a trapping agent for reactive
metabolites was investigated using an electrochemical flow-through cell for metabolism simulation coupled online to a LC system
with electrospray ionization mass spectrometric detection. The pharmaceuticals amodiaquine, an antimalarial agent, and clozapine,
an antipsychotic compound, served as model substances. By proving the successful adduct formation between the reactive metabolite
and ferrocene-labeled GSH, it could be shown that FP-GSH is an effective trapping agent which eases routine reversed-phase
LC analyses. In contrast to GSH, which is usually used for the conjugation of reactive metabolites and where the resulting
adducts often show no or only very little retention, FP-GSH facilitates the detection of the corresponding metabolite adducts
due to higher retention times. 相似文献
79.
80.
Eichelbaum M Stösser R Karpov A Dobner CK Rosowski F Trunschke A Schlögl R 《Physical chemistry chemical physics : PCCP》2012,14(3):1302-1312
We have developed a noncontact method to probe the electrical conductivity and complex permittivity of single and polycrystalline samples in a flow-through reactor in the temperature range of 20-500 °C and in various gas atmospheres. The method is based on the microwave cavity perturbation technique and allows the simultaneous measurement of microwave conductivity, permittivity and of the catalytic performance of heterogeneous catalysts without any need for contacting the sample with electrodes. The sensitivity of the method towards changes in bulk properties was proven by the investigation of characteristic first-order phase transitions of the ionic conductor rubidium nitrate in the temperature range between 20 and 320 °C, and by studying the temperature dependence of the complex permittivity and conductivity of a niobium(V)-doped vanadium-phosphorous-oxide catalyst for the selective oxidation of n-butane to maleic anhydride. Simultaneously, the catalytic performance was probed by on line GC analysis of evolving product gases making the technique a real in situ method enabling the noninvasive investigation of electronic structure-function relationships. 相似文献