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991.
992.
Development and evaluation of porous materials for carbon dioxide separation and capture 总被引:1,自引:0,他引:1
The development of new microporous materials for adsorption separation processes is a rapidly growing field because of potential applications such as carbon capture and sequestration (CCS) and purification of clean-burning natural gas. In particular, new metal-organic frameworks (MOFs) and other porous coordination polymers are being generated at a rapid and growing pace. Herein, we address the question of how this large number of materials can be quickly evaluated for their practical application in carbon dioxide separation processes. Five adsorbent evaluation criteria from the chemical engineering literature are described and used to assess over 40 MOFs for their potential in CO(2) separation processes for natural gas purification, landfill gas separation, and capture of CO(2) from power-plant flue gas. Comparisons with other materials such as zeolites are made, and the relationships between MOF properties and CO(2) separation potential are investigated from the large data set. In addition, strategies for tailoring and designing MOFs to enhance CO(2) adsorption are briefly reviewed. 相似文献
993.
Yadollah Yamini Mahnaz Ghambarian Ali Esrafili Najmeh Yazdanfar Morteza Moradi 《International journal of environmental analytical chemistry》2013,93(13):1493-1505
The objective of the present study was to develop and validate a rapid, highly sensitive, and reliable extraction method to determine acrylamide in water samples. The method was based on the derivatisation of the acrylamide in the presence of KBr, HBr and saturated Br2 solution into 2,3-dibromopropionamide and dispersive liquid–liquid microextraction (DLLME) followed by gas chromatography–electron capture detection (GC–ECD) of the analyte. Different parameters that affect the DLLME process such as types and volumes of disperser solvent, ionic strength of aqueous solution and extraction time were investigated and optimised. Under optimal conditions, excellent linearity was obtained between concentration of acrylamide and the response of ECD with correlation of determination (R2) of 0.9999. The precision of the method, which was determined by calculating the relative standard deviations (RSD) of the at least three replicate measurements, was 3.6%. The method presented in this study is sensitive enough for the determination of acrylamide in different water samples with the limit of detection (LOD) value of 1?ng?L?1. The mean percentage recoveries exceeded 91% for all of spiking levels in the real water samples. The results obtained from DLLME method are validated by EPA method 8032A. 相似文献
994.
Enrique Poulain Alberto Rubio‐Ponce Victor Hugo Uc Virineya Bertin Oscar Olvera‐Neria 《International journal of quantum chemistry》2013,113(13):1794-1802
Nitrous oxide (N2O) is an intermediate compound formed during catalysis occurring in automobile exhaust pipes. In this work, the N2O capture and activation by Pt and Pd atoms in the ground and excited states of many multiplicities are studied. Pt and Pd + N2O reactions are studied at multireference second‐order perturbation level of theory using Cs symmetry. The PtN2O (1A′, 5A′, and 5A″) species are spontaneously created from excited states. Only the 5A′ and 5A″ states exhibit N2O activation reaction paths when N2O approaches Pt end‐on by the N or O atoms side or side‐on yielding NO or N2 as products, respectively. Pt+ cations ground and excited states, capture N2O, although only Pt+ (6A′ and 6A″) states show N2O activation yielding O and N2 as products. In the Pd atom case, PdN2O (1A′ and 5A″) species are also spontaneously created from excited states. The 5A″ state exhibits N2O activation yielding N2 + O as products. Pd+ cations in both ground and excited states capture N2O; however, only the [PdN2O]+ (4A′, 4A″, 6A′, and 6A″) states in side‐on approaches and (6A′) in end‐on approach activate the N2O and yield the N2 bounded to the metal and O as product. The results obtained in this work are discussed and compared with previous calculations of Rh and Au atoms. The reaction paths show a metal–gas dative covalent bonding character. Löwdin charge population analyses for Pt and Pd active states show a binding done through charge donation and retrodonation between the metals and N2O. © 2013 Wiley Periodicals, Inc. 相似文献
995.
2‐Ethenylmethylthiobenz[d]oxazoles 9–11, on heating at high temperature in bromobenzene, underwent migration of ethenylmethyl moieties without rearrangement from sulfur to nitrogen in an internal radical capture pathway, instead of [3,3]‐sigmatropic change, to furnish 3‐ethenylmethylbenz[d]oxazole‐2(3H)‐thiones 13–15. 相似文献
996.
There is a need to develop sensitive and accurate analytical methods for determining deoxynivalenol (DON), HT-2 toxin and T-2 toxin in paprika to properly assess the relevant risk of human exposure. An optimized analytical method for determination of HT-2 toxin and T-2 toxin using capillary gas chromatography with electron capture detection and another method for determination of DON by liquid chromatography-mass spectrometry in paprika was developed. The method for determination of HT-2 toxin and T-2 toxin that gave the best recoveries involved extraction of the sample with acetonitrile-water (84:16, v/v), clean-up by solid-phase extraction on a cartridge made of different sorbent materials followed by a further clean-up in immunoaffinity column that was specific for the two toxins. The solvent was changed and the eluate was derivatized with pentafluoropropionic anhydride and injected into the GC system. The limits of detection (LOD) for T-2 and HT-2 toxins were 7 and 3 μg/kg, respectively, and the recovery rates for paprika spiked with 1000 μg toxin/kg were 71.1% and 80.1% for HT-2 and T-2 toxins, respectively. For DON determination, the optimized method consisted of extraction with acetonitrile-water (84:16, v/v) solution followed by a solid-phase extraction clean-up process in a cartridge made of different sorbent compounds. After solvent evaporation in N2 stream, the residue was dissolved and DON was separated and determined by LC-MS/MS. The LOD for this method was 14 μg DON/kg paprika sample and the DON recovery rate was 86.8%. 相似文献
997.
Liu Y Zhuang D Hou R Li J Xu G Song T Chen L Yan G Pang Q Zhu J 《Analytica chimica acta》2011,688(2):4369-190
The pituitary is responsible for multiple homeostatic functions including metabolism, growth and reproduction. Proteome analysis offers an efficient approach for a comprehensive analysis of pituitary protein expression. The pituitary is usually acquired from postmortem specimens, which may potentially affect the proteome profile by proteolysis. The aim of this study was to determine whether the postmortem pituitary could be used in proteomic analysis combining with Laser capture microdissection (LCM). Digested peptides from LCM captured prolactin (PRL) cells were separated by two dimensional-nanoscale liquid chromatography (2D-nanoLC/MS) and characterized by tandem mass spectrometry (MS). All MS/MS spectrums were searched by SEQUEST and a proteome of 1660 proteins was identified. Category analysis of the proteome revealed an extensive unbiased access to cell component proteins with diverse functional characteristics. The results demonstrated the ability of using 2D-nanoLC/MS to perform sensitive proteomic analysis on limited protein quantities through microdissection. Detailed comparisons between the proteome in question and the one derived from the prolactinoma controls at peptide and protein levels indicated that the two proteomes had similar characters. Overall, our results revealed for the first time the possibility of use of postmortem human pituitary for proteomic research which is important for further studies on disease biomarker identification and molecular mechanisms of prolactinoma tumorigenesis. 相似文献
998.
Polo M Garcia-Jares C Llompart M Cela R 《Analytical and bioanalytical chemistry》2007,388(8):1789-1798
A solid-phase microextraction method (SPME) followed by gas chromatography with micro electron capture detection for determining
trace levels of nitro musk fragrances in residual waters was optimized. Four nitro musks, musk xylene, musk moskene, musk
tibetene and musk ketone, were selected for the optimization of the method. Factors affecting the extraction process were
studied using a multivariate approach. Two extraction modes (direct SPME and headspace SPME) were tried at different extraction
temperatures using two fiber coatings [Carboxen–polydimethylsiloxane (CAR/PDMS) and polydimethylsiloxane–divinylbenzene (PDMS/DVB)]
selected among five commercial tested fibers. Sample agitation and the salting-out effect were also factors studied. The main
effects and interactions between the factors were studied for all the target compounds. An extraction temperature of 100 °C
and sampling the headspace over the sample, using either CAR/PDMS or PDMS/DVB as fiber coatings, were found to be the experimental
conditions that led to a more effective extraction. High sensitivity, with detection limits in the low nanogram per liter
range, and good linearity and repeatability were achieved for all nitro musks. Since the method proposed performed well for
real samples, it was applied to different water samples, including wastewater and sewage, in which some of the target compounds
(musk xylene and musk ketone) were detected and quantified.
Figure Stardardized Pareto charts for the main effects and interactions 相似文献
999.
1000.
A. Korgul H. Mach B. A. Brown A. Covello A. Gargano B. Fogelberg W. Kurcewicz E. Werner-Malento R. Orlandi M. Sawicka 《The European Physical Journal A - Hadrons and Nuclei》2007,32(1):25-29
Recently the first excited state in 135Sb has been observed at the unexpectedly low excitation energy of only 282keV and interpreted as mainly d
5/2 proton coupled to the 134Sn core. Based on theoretical considerations it was suggested that its low excitation energy is related to a relative shift
of the proton d
5/2 and g
7/2 orbits induced by the neutron excess. We have measured the lifetime of the 282keV state by the advanced time-delayed βγγ(t) method. The measured half-life, T
1/2 = 6.1(4)ns, yields exceptionally low limits of B(M1;5/21
+→7/21
+)≤3.0×10-4
μ
2
N and B(E2;5/21
+→7/21
+)≤54e
2
fm
4. These strongly hindered M1 and slow E2 transition rates are similar to those for the transition de-populating the first excited state at 405keV in 211Bi. Results of shell model calculations with realistic interactions are presented. The M1 decay rate was found to be extremely sensistive both to the wave function and to the M1 effective operator. 相似文献