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141.
A novel protocol for the synthesis of dye-encapsulating liposomes tagged with DNA oligonucleotides at their outer surface
was developed. These liposomes were optimized for use as signal enhancement agents in lateral-flow sandwich-hybridization
assays for the detection of single-stranded RNA and DNA sequences. Liposomes were synthesized using the reverse-phase evaporation
method and tagged with oligonucleotides by adding cholesteryl-modified DNA probes to the initial lipid mixture. This resulted
in a greatly simplified protocol that provided excellent control of the probe coverage on the liposomes and cut the preparation
time from 16 hours to just 6 hours. Liposomes were prepared using probe concentrations ranging from 0.00077 to 0.152 mol%
of the total lipid, several hydrophobic and polyethylene glycol-based spacers between the cholesteryl anchor and the probe,
and liposome diameters ranging from 208 nm to 365 nm. The liposomes were characterized by dynamic light scattering, visible
spectroscopy, and fluorescence spectroscopy. Their signal enhancement functionality was compared by using them in lateral-flow
optical biosensors for the detection of single-stranded DNA sequences. In these assays, an optimal reporter probe concentration
of 0.013 mol%, liposome diameter of 315 nm, and liposome optical density of 0.4–0.6 at 532 nm were found. The spacer length
between the cholesteryl anchor and the probe showed no significant effect on the signals in the lateral-flow assays. The results
presented here provide important data for the general use of liposomes as labels in analytical assays, with specific emphasis
on nucleic acid detection via lateral flow assays. 相似文献
142.
143.
Positively and negatively charged ionic modifications to cellulose assessed as cotton-based protease-lowering and hemostatic wound agents 总被引:1,自引:0,他引:1
J. V. Edwards Phyllis Howley Nicolette Prevost Brian Condon Judy Arnold Robert Diegelmann 《Cellulose (London, England)》2009,16(5):911-921
Recent developments in cellulose wound dressings targeted to different stages of wound healing have been based on structural
and charge modifications that function to modulate events in the complex inflammatory and hemostatic phases of wound healing.
Hemostasis and inflammation comprise two overlapping but distinct phases of wound healing wherein different dressing material
properties are required to bring pathological events under control when they present as a result of trauma or chronic wounds.
Thus, we have designed cellulose wound dressings with properties that function through modified fiber surface properties to
lower protease levels in the chronic wound and promote clotting in hemorrhaging wounds. With this in mind three finishing
chemistries utilizing traditional pad-dry-cure approaches were explored for their potential to confer charged properties to
cotton dressings. Cellulose dressings designed to remove cationic serine proteases from highly exudative chronic wounds were
created to present negatively charged fibers as an ion exchange mechanism of protease-lowering. Phosphorylated cotton and
polycarboxylic acid crosslinked cotton were prepared to examine their ability to remove human neutrophil elastase (HNE) from
surrogate wound fluid. A cellulose phosphorylation reaction utilizing sodium hexametaphosphate: urea was explored to optimize
cellulose phosphorylation as a function of HNE sequestration efficacy. Acid catalyzed cross linking of cellulose with butane-tetracarboxylic
acid also resulted in a negatively charged dressing that removed HNE from solution more effectively than phosphorylated cellulose.
Collagenase sequestration was also assessed with phosphorylated cellulose and polycarboxylic acid cross linked cellulose derivatives.
Butanetetracarboxylic acid and phosphorylated cellulose functioned to remove collagenase from solution most effectively. Cellulose
dressings designed to accelerate thrombosis and aggregation of blood platelets were prepared with a view to examining derivatized
cotton fibers bearing a net positive charge to promote hemostasis. Cellulose and chitosan dressings bearing an aminoglucan
functionality were created by grafting chitosan on cotton and preparing aminized cotton. The preparation of chitosan-grafted
cotton dressings was completed with a citric acid grafting onto cellulose. Aminized cotton was functionalized as an ethylamino-ether
cellulose derivative. The chitosan-grafted and aminized cotton demonstrated a dose response gelling of citrated sheep blood. 相似文献
144.
Kroly Vkey Duncan M. F. Edwards Luigi F. Zerilli Marianna Mk Jzsef Tams Vittorio Raverdino Antonio Selva 《Journal of mass spectrometry : JMS》1990,25(9):465-474
Results of 16 different mass spectrometric ionization and sample-introduction methods are compared for the case of a thermally very labile antibiotic, rifapentine. These suggest that extensive thermal decomposition occurs during evaporation when the sample can come into contact with hot metal parts, usually the source housing. The intensity of the molecular ion and the extent of fragmentation depend on various parameters, such as the ionization process, positive or negative-ion detection and the type of sample introduction. The most informative methods for rifapentine seem to be ‘in-beam’ electron impact, negative ionization with particle beam and direct liquid introduction interfaces and positive- and negative-ion fast atom bombardment. 相似文献
145.
S. C. Goheen B. D. McVeety T. W. Clauss R. B. Lucke M. W. Ligotke J. A. Edwards J. S. Fruchter 《Journal of Radioanalytical and Nuclear Chemistry》1996,207(1):81-91
Organic species from the headspace of one Hanford radioactive waste tank are described. Samples were collected either using a sorbent trap or a SUMMATM canister and were analyzed by gas chromatograph and mass spectrometry. The headspace contained several organic components, including alkanes, alkenes, ketones, aldehydes, organic nitriles, and chlorinated hydrocarbons. Sorbent trap samples were designed to collect only normal paraffin hydrocarbons (NPHs). A comparison of NPH data from sorbent traps and SUMMATM cans revealed results of 693 and 1320 mg/m3, NPH respectively. Significant differences were observed in NPH values when samples were collected at different times, or at different locations in the tank. These data suggest either the time of collection, or the position of the sampling device are important variables in the analysis of organic species from Hanford tanks. 相似文献
146.
Carmona D Lahoz FJ Atencio R Edwards AJ Oro LA Lamata MP Esteban M Trofimenko S 《Inorganic chemistry》1996,35(9):2549-2557
Treatment of the metallo ligands [ML(pz)(2)(Hpz)] (pz = pyrazolate; L = C(5)Me(5), M = Ir (1); L = mesitylene, M = Ru (3)) with [M'Cl{HB(3-i-Pr-4-Br-pz)(3)}] (M' = Co (4), Ni (5)) yields heterodinuclear complexes of formula [LM(&mgr;-pz)(2)(&mgr;-Cl)M'{HB(3-i-Pr-4-Br-pz)(3)}] (L = C(5)Me(5); M = Ir; M' = Co (6), Ni (7). L = mesitylene; M = Ru; M' = Co (8)). The related complex [Ru(eta(6)-p-cymene)(pz)(2)(Hpz)] (2) reacts with equimolar amounts of 4 or 5 to give mixtures of the corresponding bis(&mgr;-pyrazolato) &mgr;-chloro complexes [(eta(6)-p-cymene)Ru(&mgr;-pz)(2)(&mgr;-Cl)M'{HB(3-i-Pr-4-Br-pz)(3)}] (M' = Co (9), Ni (10)) and the triply pyrazolato-bridged complexes [(eta(6)-p-cymene)Ru(&mgr;-pz)(3)M'{HB(3-i-Pr-4-Br-pz)(3)}] (M' = Co (11), Ni (12)). Complex 1 reacts with 5 in the presence of KOH to give the IrNi complex [(eta(5)-C(5)Me(5))Ir(&mgr;-pz)(3)Ni{HB(3-i-Pr-4-Br-pz)(3)}] (13) whereas its reaction with 4 and KOH rendered the bis(&mgr;-pyrazolato) &mgr;-hydroxo complex [(eta(5)-C(5)Me(5))Ir(&mgr;-pz)(2)(&mgr;-OH)Co{HB(3-i-Pr-4-Br-pz)(3)}] (14). The molecular structure of the heterobridged IrCo complex (6) and those of the homobridged RuNi (12) and IrNi (13) complexes have been determined by X-ray analyses. Compound 6 crystallizes in the monoclinic space group P2(1)/n, with a = 10.146(5) ?, b = 18.435(4) ?, c = 22.187(13) ?, beta = 97.28(4) degrees, and Z = 4. Complex 12 is monoclinic, space group P2(1), with a = 10.1169(7) ?, b = 21.692(2) ?, c = 11.419(1) ?, beta = 112.179(7) degrees, and Z = 2. Compound 13 crystallizes in the monoclinic space group Cc, with a = 13.695(2) ?, b = 27.929(6) ?, c = 13.329(2) ?, beta = 94.11(4) degrees, and Z = 4. All the neutral complexes 6, 12, and 13 consist of linear M.M'.B backbones with two (6) or three (12, 13) pyrazolate ligands bridging the dimetallic M.M' units and three substituted 3-i-Pr-4-Br-pz groups joining M' to the boron atoms. The presence in the proximity of the first-row metal M' of the three space-demanding isopropyl substituents of the pyrazolate groups induces a significant trigonal distortion of the octahedral symmetry, yielding clearly different M'-N bond distances on both sides of the ideal octahedral coordination sphere of these metals. 相似文献
147.
Roca M Marcos MD Amorós P Beltrán-Porter A Edwards AJ Beltrán-Porter D 《Inorganic chemistry》1996,35(19):5613-5621
A general synthetic approach to rationalize the solution preparative chemistry of oxovanadium phosphates containing organic species as structural directing agents is presented. Careful attention is payed to the hydrolysis and condensation processes involving the ionic species in solution, and a simple restatement of the partial charge model (PCM) has been used in order to organize the experimental results. The structure of a new V(IV)-Fe(III) bimetallic oxovanadium phosphate, [H(3)N(CH(2))(2)NH(3)](2)[H(3)N(CH(2))(2)NH(2)] [Fe(III)(H(2)O)(2)(V(IV)O)(8)(OH)(4)(HPO(4))(4)(PO(4))(4)].4H(2)O, has been determined by X-ray single crystal diffraction methods. This compound crystallizes in the monoclinic system, space group P2(1)/n and the cell dimensions are as follows: a = 14.383(3) ?, b = 10.150(2) ?, c = 18.355(4) ?, and beta = 90.39(3) degrees (Z = 2). The existence of a complex intercrossing channel system, including a very large channel of 18.4 ? of diameter (in which both water molecules and ethylenediamine species are located), is the more interesting feature of this structure. Thermal decomposition, including the dehydration/rehydration process, has been studied by thermal analysis and variable temperature X-ray powder diffraction techniques. A complementary SEM study of the different intermediate decomposition products is presented. 相似文献
148.
149.
We have simulated the scattering in a pulsed atomic beam evaporated from a superfluid 4He film. Assuming that the atoms leaving the surface of the film have an equilibrium Maxwellian distribution, we find that the experimentally observed deviations from Lambert's law are explained by scattering of the atoms after evaporation. 相似文献
150.