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61.
The prediction of soil metal phytoavailability using the chemical extractions is a conventional approach routinely used in soil testing. The adequacy of such soil tests for this purpose is commonly assessed through a comparison of extraction results with metal contents in relevant plants. In this work, the fractions of selected risk metals (Al, As, Cd, Cu, Fe, Mn, Ni, Pb, Zn) that can be taken up by various plants were obtained by optimized BCR (Community Bureau of Reference) three-step sequential extraction procedure (SEP) and by single 0.5 mol L(-1) HCl extraction. These procedures were validated using five soil and sediment reference materials (SRM 2710, SRM 2711, CRM 483, CRM 701, SRM RTH 912) and applied to significantly different acidified soils for the fractionation of studied metals. The new indicative values of Al, Cd, Cu, Fe, Mn, P, Pb and Zn fractional concentrations for these reference materials were obtained by the dilute HCl single extraction. The influence of various soil genesis, content of essential elements (Ca, Mg, K, P) and different anthropogenic sources of acidification on extraction yields of individual risk metal fractions was investigated. The concentrations of studied elements were determined by atomic spectrometry methods (flame, graphite furnace and hydride generation atomic absorption spectrometry and inductively coupled plasma optical emission spectrometry). It can be concluded that the data of extraction yields from first BCR SEP acid extractable step and soil-plant transfer coefficients can be applied to the prediction of qualitative mobility of selected risk metals in different soil systems. 相似文献
62.
José Luis Fonseca María José Sosa Gabriela Petroselli Rosa Erra-Balsells Matías I. Quindt Sergio M. Bonesi Alexander Greer Edyta M. Greer Andrés H. Thomas Mariana Vignoni 《Photochemistry and photobiology》2023,99(2):593-604
Here, we provide mechanistic insight to the photocleavage of a compound in the folate family, namely pteroic acid. A bis-decyl chain derivative of pteroic acid was synthesized, structurally characterized and photochemically investigated. We showed that, like folic acid, pteroic acid and the decylated derivative undergo a photocleavage reaction in the presence of H2O, while no reaction was observed in methanol solution. Furthermore, density functional theory calculations were carried out to predict relative stabilities of hypothetical mono-, bis- and tris-decylated pteroic acid derivatives to help rationalize the regioselectivity of the bis-decyl pteroic acid product. Additionally, the lipophilicity of the bis-decyl pteroic acid appears to confer a hydrophobic property enabling an interaction with biomembranes. 相似文献
63.
Ján Medved’ Milan Kališ Ingrid Hagarová Peter Matúš Marek Bujdoš Jana Kubová 《Chemical Papers》2008,62(2):168-175
Determination of thallium in polluted environmental samples and their extracts obtained by a modified BCR three-step sequential
extraction procedure was used to study thallium distribution and mobility in the monitored polluted area affected by acidification
(Šobov, Central Slovakia). The results of fractionation applied to 5 soil certified reference materials and 14 environmental
samples show that the vast majority of thallium occurred in the residual fraction. This means that highly toxic thallium is
strongly entrapped in the parent rock materials remains immobile and its environmental toxicity is therefore reduced. The
limit of detection for thallium in the studied fractions was lower than 0.050 mg kg−1, the precision (RSD) of the ultratrace determination of thallium in the studied fractions was better than 17 % and the accuracy
of the used method was verified by analyzing certified reference materials.
Presented at the XVIIIth Slovak Spectroscopic Conference, Spišská Nová Ves, 15–18 October 2006. 相似文献
64.
65.
Proteomic analysis reveals metabolic changes during yeast to hypha transition in Yarrowia lipolytica
Morín M Monteoliva L Insenser M Gil C Domínguez A 《Journal of mass spectrometry : JMS》2007,42(11):1453-1462
Fungal dimorphism is important for survival in different environments and has been related to virulence. The ascomycete Yarrowia lipolytica can grow as yeast, pseudomycelial or mycelial forms. We have used a Y. lipolytica parental strain and a Deltahoy1 mutant, which is unable to form hypha, to set up a model for dimorphism and to characterize in more depth the yeast to hypha transition by proteomic techniques. A two-dimensional gel electrophoresis (2-DE) based differential expression analysis of Y. lipolytica yeast and hyphal cells was performed, and 45 differentially expressed proteins were detected; nine with decreased expression in hyphal cells were identified. They corresponded to the S. cerevisiae homologues of Imd4p, Pdx3p, Cdc19, Sse1p, Sol3p, Sod2p, Xpt1p, Mdh1p and to the unknown protein YALIOB00924g. Remarkably, most of these proteins are involved in metabolic pathways, with four showing oxidoreductase activity. Furthermore, taking into account that this is the first report of 2-DE analysis of Y. lipolytica protein extracts, 35 more proteins from the 2D map of soluble yeast proteins, which were involved in metabolism, cell rescue, energy and protein synthesis, were identified. 相似文献
66.
Natalya V. Likhanova Rafael Martínez‐Palou M. Aurora Veloz Diana J. Matías Victor E. Reyes‐Cruz Herbert Höpfl Octavio Olivares 《Journal of heterocyclic chemistry》2007,44(1):145-153
67.
Vlastimil Matějec Miroslav Chomát Miloš Hayer Ivan Kašík Daniela Berková Fethi Abdelmalek Nicole Jaffrezic-Renault 《Czechoslovak Journal of Physics》1999,49(5):883-888
The paper summarizes results achieved in the Institute of Radio Engineering and Electronics in the field of investigation
and fabrication of novel fiber-optic structures for evanescent-wave chemical sensing. Several approaches for increasing the
evanescent-wave sensitivity of multimode silica optical fibers to gaseous and liquid chemicals are shown. These approaches
make use of the decrease of the core diameter in sectorial and capillary sectorial fibers, modification of trajectories of
optical rays in the cores of inverted-graded-index fibers, tailoring of the refractive index of porous layers applied on silica
cores, an output mode filter preventing the detection of rays propagating at low axial angles or fibers bent in single or
multiple turns.
Presented at the 1st Czech-Chinese Workshop “Advanced Materials for Optoelectronics”, Prague, Czech Republic, June 13–17,
1998.
This work was supported by the Grant Agency of the Czech Republic (projects No. 102/96/0939 and No. 102/98/1358) and by joint
project No. 4104 of AS CR and CNRS, France. 相似文献
68.
J. Kaňka P. Peterka P. Honzátko V. Matějec I. Kašík 《Czechoslovak Journal of Physics》1999,49(5):889-894
We have proposed and demonstrated experimentally that an Er-doped twin-core fibre (ErTCF) can be employed as a tracking narrow-band
filter in fibre ring lasers for line narrowing and enhancement of the spectral stability. The device mimics a saturable absorber
with inhomogeneous broadening. The slow erbium ion saturation dynamics in the ErTCF prevents wavelength hopping whilst it
enables the filter to track the operation wavelength on its tuning. We have improved the device operation by utilizing the
inherent filtering effect of a twin-core fibre coupler.
Presented at the 1st Czech-Chinesse Workshop “Advanced Materials for Optoelectronics”, Prague, Czech Republic, June 13–17,
1998
This research has been in part supported by the Commission of the European Union in the frame of Copernicus programme, Project
# 7882 and by the Ministry of Education of the Czech Republic under Contract OC 241.10/1998. 相似文献
69.
A. K. Arof N. A. Mat Nor N. R. Ramli N. Aziz I. M. Noor R. M. Taha 《Optical and Quantum Electronics》2017,49(1):37
Photoelectrodes of dye-sensitized solar cells (DSSCs) have been prepared using nanosized titanium dioxide that have soaked in a solution of different saffron (Crocus sativus L.) spice content in ethanol. The optimized polyacrylonitrile (PAN)-based gel polymer electrolyte with 40.93 wt.% ethylene carbonate, 37.97 wt.% propylene carbonate, 4.37 wt.% tetrapropylammonium iodide, 9.86 wt.% PAN, 1.24 wt.% 1-butyl-3-methylimidazolium iodide, 4.35 wt.% lithium iodide and 1.28 wt.% iodine has been used as the electrolyte for DSSC. The electrolyte has conductivity of 2.91 mS cm?1 at room temperature (298 K). DSSCs were also sensitized with saffron solution that has been added with 30 wt.% chenodeoxycholic acid (CDCA) co-adsorbent and designated as DSSC P4. The solar cell converts light-to-electricity at an efficiency of 0.31%. This is 29% enhancement in efficiency for the DSSC without addition of CDCA in the saffron-ethanol solution. The DSSC exhibits current density at short-circuit (J sc ) of 1.26 mA cm?2, voltage at open circuit (V oc ) of 0.48 V and 51% fill factor. DSSC P4 also exhibits the highest incident photon-to-current density of more than 40% at 340 nm wavelength. 相似文献
70.
Nor Hakimin Abdullah Mazlan Mohamed Norshahidatul Akmar Mohd Shohaimi Azwan Mat Lazim Ahmad Zamani Abdul Halim Nurasmat Mohd Shukri Mohammad Khairul Azhar Abdul Razab 《Molecules (Basel, Switzerland)》2021,26(15)
The presence of organic dyes from industrial wastewater can cause pollution and exacerbate environmental problems; therefore, in the present work, activated carbon was synthesized from locally available oil palm trunk (OPT) biomass as a low-cost adsorbent to remove synthetic dye from aqueous media. The physical properties of the synthesized oil palm trunk activated carbon (OPTAC) were analyzed by SEM, FTIR-ATR, and XRD. The concurrent effects of the process variables (adsorbent dosage (g), methylene blue (MB) concentration (mg/L), and contact time (h)) on the MB removal percentage from aqueous solution were studied using a three-factor three-level Box–Behnken design (BBD) of response surface methodology (RSM), followed by the optimization of MB adsorption using OPTAC as the adsorbent. Based on the results of the analysis of variance (ANOVA) for the three parameters considered, adsorbent dosage (X1) is the most crucial parameter, with an F-value of 1857.43, followed by MB concentration (X2) and contact time (X3) with the F-values of 95.60 and 29.48, respectively. Furthermore, the highest MB removal efficiency of 97.9% was achieved at the optimum X1, X2, and X3 of 1.5 g, 200 mg/L, and 2 h, respectively. 相似文献