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121.
Usha Prasad Andley G. S. Singhal Prasanna Mohanty 《Photochemistry and photobiology》1981,33(2):235-242
Abstract The fluorescence intensity of the extrinsic chromophore 1-anilino-naphthalene-8-sulfonate (ANS) bound to pea chloroplast fragments shows a sigmoidal rise as the pH of the suspending medium is decreased by the addition of HC1. The abrupt increase occurs at pH – 4.5. A 70% decrease in the maximal fluorescence intensity (pH range 3.5-4.5) of bound ANS was observed when soluble chloroplast proteins were removed by washing with water. Extraction of chloroplast membranes with 6 M guanidine-HC1 abolishes the acid–induced enhancement of ANS fluorescence. However, the subsequent removal of lipids (by 80% acetone extraction) from the guanidine-HC1-extracted naked membranes restores the acid-induced fluorescence increase. These results suggest that ANS binds mainly to the surface of the chloroplast membrane and the fluorescence changes of ANS by acidification mainly reflect the changes in the associated proteins. The lack of enhancement of the fluorescence of ANS by acidification of the guanidine-HCl treated membranes and the recovery of the acid-induced fluorescence rise after extraction of the lipids from the guanidine-HCl treated membranes suggest that the boundary lipids somehow prevent the entry of the ANS molecules into the hydrophobic interior of the naked membrane. The lipid-depleted, guanidine-HCl extracted naked membrane fragments do not show any shift in the position of the peak of emission of ANS (λ= 470 nm) upon acidification as the lipid-depleted preparations without guanidine-HCl treatment do (shift from 460 to 470 nm). Divalent cations (Mn2+, Ca2+, Mg2+) also increased ANS fluorescence intensities when added to both types of lipid-depleted chloroplast preparations. A comparative analysis of ANS fluorescence bound to the lipid-depleted and guanidine-HCl treated chloroplast fragments with that of just lipid-depleted fragments shows that the acidification of the latter brings about a greater change in the value of the relative binding sites (n) and the dissociation constant kd of ANS than the protonation of the former. The role of chloroplast protein and lipid components in the structural changes of the thylakoid membrane imposed by external perturbations is discussed. 相似文献
122.
W. E. Collins A. H. Welch J. H. Hamilton A. V. Ramayya N. C. Singhal 《Zeitschrift für Physik A Hadrons and Nuclei》1978,285(1):31-32
The gamma-gamma directional correlation of the 2+′-2+-0+, 913(Iγ=1.69)-934(Iγ =100)keV cascade in92Nb decay has been investigated with a NaI-Ge(Li) system. Our results yieldδ=?0.013 ?0.024 +0.041 . This is one of a very few cases where the second 2+ to first 2+ transition is not predominatelyE2. This may be related to the closed neutron shell, as earlier suggested. [Radioactivity92Zr; measuredγ-γ(θ), deducedδ] 相似文献
123.
Abstract
Deubiquitylating enzymes (DUBs) can hydrolyze a peptide, amide, ester or thiolester bond at the C-terminus of UBIQ (ubiquitin), including the post-translationally formed branched peptide bonds in mono- or multi-ubiquitylated conjugates. DUBs thus have the potential to regulate any UBIQ-mediated cellular process, the two best characterized being proteolysis and protein trafficking. Mammals contain some 80–90 DUBs in five different subfamilies, only a handful of which have been characterized with respect to the proteins that they interact with and deubiquitylate. Several other DUBs have been implicated in various disease processes in which they are changed by mutation, have altered expression levels, and/or form part of regulatory complexes. Specific examples of DUB involvement in various diseases are presented. While no specific drugs targeting DUBs have yet been described, sufficient functional and structural information has accumulated in some cases to allow their rapid development.Publication history
Republished from Current BioData's Targeted Proteins database (TPdb; http://www.targetedproteinsdb.com).124.
Hongjing Sun Michele M. Kim Yi Hong Ong Andreea Dimoft Sunil Singhal Theresa M. Busch Keith A. Cengel Timothy C. Zhu 《Photochemistry and photobiology》2023,99(2):814-825
Photodynamic therapy (PDT) has been used to treat malignant pleural mesothelioma. Current practice involves delivering light to a prescribed light fluence with a point source, monitored by eight isotropic detectors inside the pleural cavity. An infrared (IR) navigation system was used to track the location of the point source throughout the treatment. The recorded data were used to reconstruct the pleural cavity and calculate the light fluence to the whole cavity. An automatic algorithm was developed recently to calculate the detector positions based on recorded data within an hour. This algorithm was applied to patient case studies and the calculated results were compared to the measured positions, with an average difference of 2.5 cm. Calculated light fluence at calculated positions were compared to measured values. The differences between the calculated and measured light fluence were within 14% for all cases, with a fixed scattering constant and a dual correction method. Fluence-surface histogram (FSH) was calculated for photofrin-mediated PDT to be able to cover 80% of pleural surface area to 50 J cm−2(83.3% of 60 J cm−2). The study demonstrates that it will be possible to eliminate the manual measurement of the detector positions, reducing the patient's time under anesthesia. 相似文献
125.
Sumedha Ahuja Mahesh Kumar Pankaj Kumar V. K. Gupta R. K. Singhal Achchelal Yadav Bhupinder Singh 《Journal of Radioanalytical and Nuclear Chemistry》2014,300(1):199-212
Applications involving radioisotopes and radiations reveal a great promise particularly for the welfare of the society. However, in the event of a nuclear accident, the direct and indirect effect of radionuclide and radiation transfers in soil–plant–air environment are envisaged on almost all the components of the food chain. It also assumes significance as we often overlook the fact that radiations, emitted by any radioisotope although cannot be seen or felt, interacts with matter and could alter its biochemical, biophysical and biological characteristics. The interaction of ionizing radiation with human body and consequent biological effects are well characterized and quantified using data derived from the radiation workers and/or the nuclear accidents around the world. However, radiation impact on agriculture viz a viz economic productivity are not well understood and available data is scanty, scattered and inconclusive. At the plant level the effects could be visualized at morphological, biochemical, physiological and/or biophysical levels, where the magnitude of the effected change depends heavily on the exposure dose, soil, farm management and other environmental variables. This review attempts to collate and critically analyze the available researches on how the ionizing radiation might interact with crops at the whole plant or tissue or cell level to affect economic yield under various edaphic variables where not only the productivity but also the quality of the agri-produce may become vulnerable. 相似文献
126.
R.K. Singhal A. Samariya Y.T. Xing T. Shripathi 《Journal of magnetism and magnetic materials》2010,322(15):2187-3169
Through simple hydrogen annealing treatment, we observed robust inducement of room temperature ferromagnetism (RTFM) in ZnO:Co (5%) pellets. The hydrogen mediated magnetic transition is accompanied by electronic structure plus bonding modifications with no structural deviations or creation of secondary phases, as evidenced by XRD and photoemission investigations. Our findings reveal a route correlation of oxygen vacancies with the observed RTFM. In particular, we systematically investigated the time controlled re-heating consequences on hydrogenated sample. The H-induced RTFM and subsequent modifications viz. electronic structure, transport properties and bonding effect gradually retrace back upon evaporating the hydrogen. 相似文献
127.
R. K. Singhal J. Preetha Rupali Karpe P. Hema Ajay Kumar V. M. Joshi A. K. Ranade A. G. Hegde 《Journal of Radioanalytical and Nuclear Chemistry》2009,279(1):301-306
During this work the determination of uranium in the range of μg·L−1 to tens of μg·L−1 was done by alpha-spectrometry after electroplating the aliquots of water sample using (NH4)2SO4 as an electrolyte. In general, the determination of uranium by alpha-spectrometry needs its separation from other transuranics
specially thorium. The process described here does not involve any sample digestion and radiochemical separation of uranium
from other transuranics. In this method an aliquot (1 to 3 mL) of the sample was dried and dissolve in (NH4)2SO4 and thereafter the sample was electroplated on a stainless steel (SS) planchet by using an electrochemical cell of special
design. The proposed techniques have a distinct advantage over the determination of uranium by adsorptive stripping voltammetry
(AdSV) in which uranium-chloranilic (2,5-dichloro-3,6-dihydroxy-1,4-benzoquinone) acid complex was used for concentrating
the uranium from the solution. Since in the case of AdSv, the determination of uranium was not possible for samples having
dissolved organic carbon (DOC) more than 15 mg·L−1 and Cl− concentration is in the range of 40,000 μ·g−1. In the case of spike experiments with 232U the recovery was observed in the range of 90–95% in aqueous medium having higher concentration of Cl− and DOC as indicated above. 相似文献
128.
Manish Yadav Vivek Upadhyay Vipul Chauhan Gajendra Solanki Alpa Jani Girin A. Baxi Puran Singhal Pranav S. Shrivastav 《Chromatographia》2010,72(3-4):255-264
A selective, sensitive and high throughput LC–MS–MS method has been developed and validated for the chromatographic separation and quantitation of tolterodine (TOL) and its metabolite 5-hydroxymethyl TOL in human plasma. Sample clean-up concerned liquid–liquid extraction of the drug, metabolite and their respective labelled internal standards from 300 μL human plasma. Both the analytes were chromatographically separated on a Symmetry C18 (100 mm × 4.6 mm, 5 μm particle size) analytical column using 10 mM ammonium formate (pH 5.0 ± 0.1, adjusted with formic acid) and acetonitrile (35:65, v/v) as the mobile phase with a resolution factor of 2.72. The method was validated over the concentration range of 0.025–10.0 ng mL?1 for both analytes. The process efficiency found for TOL and its metabolite was 98.3 and 99.5%, respectively. The method was successfully applied to a pivotal bioequivalence study in 41 healthy human subjects after oral administration of a 2 mg tablet formulation under fasting conditions. 相似文献
129.
A series of Bi2O3–BaO–SiO2–RxOy (designated BiBaSi glass) glass sealants doped with different contents of α-Al2O3 have been investigated. Al2O3 was added as a modifier to affect the structure and the behavior of the glass. The thermal properties such as glass transition temperature (Tg), softening temperature (Tf) and coefficient of thermal expansion (CTE) were measured by a dilatometer. The sealing performance was investigated by sealing a SOFC single cell stack and measuring its open circuit voltage (OCV). Tg, Tf and suitable usage temperature of the sealants increased with increasing Al2O3 content in the glass, while CTE decreased. When the Al2O3 content was lower than 10 wt.%, excellent sealing performance was observed. 相似文献
130.
Sonal Singhal Amit Kumar Chawla Sandeep Nagar Hari Om Gupta Ramesh Chandra 《Journal of nanoparticle research》2010,12(4):1415-1421
Thin films of Zn1−x
Cd
x
S (0.1 ≤ x ≤ 0.5) were prepared by using pulsed laser ablation technique on corning glass substrates. Phase transition from cubic to
hexagonal in Zn1−x
Cd
x
S films is determined by X-ray diffraction analysis. We observed a lowering in the phase transition temperature with increase
in the cadmium concentration. Transmission electron microscopy suggests the crystalline nature of thin films with average
particle size of 15 nm. The grown Zn1−x
Cd
x
S samples show the high peak intensity ratio of the near band edge emission to the defect center luminescence even at room
temperature, which indicates the small concentration of complex defects in the samples. Photoluminescence measurement show
stoichiometric dependence of the energy band gap and is found to have quadratic dependence on x. 相似文献