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141.
An automated vapor pressure apparatus has been used to obtain highly precise values of the total pressure and composition of aqueous solutions of ethanol and of 2-propanol in the water-rich region at 25 and 35°C. From these results, values of the partial pressures and fugacities of the components and osmotic coefficients have been inferred. Interaction virial coefficients derived from the present results are compared with interaction parameters previously reported for alcohol molecules in dilute aqueous solution. A discussion is given of the relative importance of hydrophobic effects and hydrogen-bonding in producing the unusual thermodynamic properties of aqueous alcohol solutions. 相似文献
142.
Barlow S Risko C Coropceanu V Tucker NM Jones SC Levi Z Khrustalev VN Antipin MY Kinnibrugh TL Timofeeva T Marder SR Brédas JL 《Chemical communications (Cambridge, England)》2005,(6):764-766
The E-4,4'-bis[di(p-anisyl)amino]stilbene cation is a class-III mixed-valence species with electronic coupling comparable to that in its biphenyl-bridged analogue, whereas its tolane-bridged analogue belongs to class II. 相似文献
143.
Pretreatment of softwood by acid-catalyzed steam explosion followed by alkali extraction 总被引:2,自引:0,他引:2
Schell Daniel Nguyen Quang Tucker Melvin Boynton Brian 《Applied biochemistry and biotechnology》1998,(1):17-24
A process for converting lignocellulosic biomass to ethanol hydrolyzes the hemicellulosic fraction to soluble sugars (i.e.,
pretreatment), followed by acid- or enzyme-catalyzed hydrolysis of the cellulosic fraction. Enzymatic hydrolysis may be improved
by using an alkali to extract a fraction of the lignin from the pretreated material. The removal of the lignin may increase
the accessibility of the cellulose to enzymatic attack, and thus improve overall economics of the process, if the alkali-treated
material can still be effectively converted to ethanol.
Pretreated Douglas fir produced by a sulfuric-acid-catalyzed steam explosion was treated with NaOH, NH4OH, and lime to extract some of the lignin. The treated material, along with an untreated control sample, was tested by an
enzymatic-digestion procedure, and converted to ethanol by simultaneous saccharification and fermentation using a glucose-fermenting
yeast. NaOH was most effective at removing lignin (removed 29%), followed by NH4OH and lime. However, the susceptibility of
the treated material to enzymatic digestion was lower than the control and decreased with increasing lignin removal. Ethanol
production was similar for the control and NaOH-treated material, and lower for NH4OH- and lime-treated material. 相似文献
144.
Crystals of [C16H36N]+[Cl3COPt]? are monoclinic, space group P21/n, with a 14.949(8), b 8.892(7), c 18.232(10) Å, β 105.5(3)°, Z 4. The structure has been refined by least-squares to a final R of 0.042 for 2358 counter intensities. The PtCl bond lengths in the square-planar anion are not significantly different (mean value 2.291 Å) and the PtC (carbonyl) bond length is 1.82 Å.Conclusions are drawn on the factors affecting the trans influence in this complex and a number of related square planar PtII chloro-complexes. 相似文献
145.
L. F. Larkworthy D. C. Povey G. W. Smith B. J. Tucker 《Journal of chemical crystallography》1989,19(3):439-450
The cobalt atoms in both [Co(NO)(sacacen)] and [Co(NO)(7-Mesalen)] {sacacenH2 isNN-ethylenebis(monothioacetylacetoneimine) and 7-MesalenH2 isNN-ethylenebis(2-hydroxyacetophenoneimine)} are 5-coordinate, with a tetragonal-pyramidal arrangement of donor atoms. The cobalt atom in [Co(NO)(sacacen)] lies just above the plane defined by the SNNS donor atoms of the quadridentate ligand, and the nitrosyl group occupies the apical position. A similar geometry is defined by the ONNO donor atoms and the NO group in [Co(NO)(7-Mesalen)]. The Co-N-O angles are strongly bent, as predicted from15N-nmr studies (127.2(6)°[Co(NO)(sacacen)] and 127.4(3)°[Co(NO)(7-Mesalen)]). Both nitrosyls crystallize in the monoclinic system. For [Co(NO)(sacacen)],a=8.501,b=12.673,c=13.866 Å,=95.00°,Z=4 and space groupP21/c. The structure was determined by the heavy-atom method, usingMo K diffractometer data, and refined by full matrix least squares toR=0.062 for 2920 observed reflections. For [Co(NO)(7-Mesalen)],a=9.461,b=13.053,c=13.456,=99.32°,Z=4 and space groupP21/c. The structure was determined as above toR=0.040 for 2461 observed reflections. 相似文献
146.
147.
D. A. Wade C. Mao A. C. Hollenbeck S. A. Tucker 《Analytical and bioanalytical chemistry》2001,369(3-4):378-384
The ability of pyridinium chloride (PC) to selectively quench alternant as opposed to nonalternant polycyclic aromatic hydrocarbons
(PAHs) in organized media is examined. PC was previously shown to be a selective quenching agent of alternant PAHs in neat
polar solvents. Carboxylate-terminated poly(amido) amine (PAMAM-CT) dendrimers and anionic surfactants – sodium dodecanoate
(SD), sodium octanoate (SO), and sodium dodecylsulfate (SDS) – were chosen as the solubilizing media for this study. Selective
quenching of alternant PAHs is observed in the presence of the SDS and SO micelles. However, the extent of PAH quenching in
SO is significantly reduced compared to PAHs dissolved in either water or SDS micelles. In the case of the smaller generation
4.5 (G4.5) PAMAM-CT dendrimers, PC was prevented from quenching both alternant and nonalternant PAHs to any appreciable extent.
The dendrimer is able to “protect” the PAHs from the PC quencher that resides at the dendrimer surface. Both, SD and G5.5
PAMAM-CT precipitated out of solution with the addition of PC. Differences between traditional micelles and “unimolecular
micelle” dendrimers were also examined. These studies further confirm that the PAHs did not reside in the “analogous” palisade
region of the dendrimers as they do in micelles. The PAHs must reside in the outermost branches of the dendrimer, but sufficiently
far enough away from the charged surface groups, where PC associated, to prevent fluorescence quenching. This work further
illustrates the differences between “unimolecular micelle” dendrimers and traditional micelles.
Received: 27 July 2000 / Revised: 25 September 2000 / Accepted: 27 September 2000 相似文献
148.
Quang A. Nguyen Fred A. Keller Melvin P. Tucker Charles K. Lombard Bryan M. Jenkins David E. Yomogida Valentino M. Tiangco 《Applied biochemistry and biotechnology》1999,78(1-3):455-472
A mixed solids waste (MSW) feedstock, comprising construction lumber waste (35% oven-dry basis), alm ond treeprunings (20%),
wheat straw (20%), office waste paper (12.5%), and newsprint (12.5%), was converted to ethanol via dilute-acid pretreatment
followed by enzymatic hydrolysis and yeast fermentation. The MSW was pretreated with dilute sulfuricacid (0.4% w/w) at 210°C
for 3 min in a 4-L stea mexplosion reactor, then washed with water to recover the solubilized hemicellulose. The digestibility
of water-washed, pretreated MSW was 90% in batch enzymatic hydrolysis at 66 FPU/g cellulose. Using an enzyme-recycle bioreactor
system, greater than 90% cellulose hydrolysis was achieved at a net enzyme loading of about 10 FPU/g cellulose. Enzyme recycling
using mebrane filtration and a fed-batch fermentation technique is a promising option for significantly reducing the cost
of enzyme in cellulose hydrolysis. The hexosesugars were readily fermentable using a Saccharomyces cerevisiae yeast strain that was adapted to the hydrolysate. Solid residue after enzyme digestion was subjected to various furnace experiments
designed to assess the fouling and slagging characteristics. Results of these analyses suggest the residue to be of a low
to moderate slagging and fouling type if burned by itself. 相似文献
149.
Tammy Kay Hayward Jenny Hamilton David Templeton Ed Jennings Mark Ruth Arun Tholudur James D. McMillan Mel Tucker Ali Mohagheghi 《Applied biochemistry and biotechnology》1999,77(1-3):293-309
National Renewable Energy Laboratory (NREL) has developed a conditioning process that decreases acetic acid levels in pretreated
yellow poplar hydrolysate. Trichoderma reesei is sensitive to acetic acid and this conditioning method has enabled applied cellulase production with hardwoods. T. reesei strains QM9414, L-27, RL-P37, and Rut C-30 were screened for growth on conditioned hydrolysate liquor. Tolerance to hydrolysate
was found to be strain-dependent. Strain QM9414 was adapted to grow in 80% (v/v) conditioned hydrolysate (40 g/L of soluble
sugars and 1.6 g/L acetic acid from pretreated poplar). However, enzyme production was highest at 20% (v/v) hydrolysateusing
strain L-27. Cellulasetiters of 2–3 International Filter Paper Units (IFPU)/mL were achieved using pretreated yellow poplar
liquors and solids as the sole carbon sources. 相似文献
150.
This paper addresses questions involving the sharpness of Vojta's conjecture and Vojta's inequality for algebraic points on curves over number fields. It is shown that one may choose the approximation term mS(D,-) in such a way that Vojta's inequality is sharp in Theorem 2.3. Partial results are obtained for the more difficult problem of showing that Vojta's conjecture is sharp when the approximation term is not included (that is, when D=0). In Theorem 3.7, it is demonstrated that Vojta's conjecture is best possible with D=0 for quadratic points on hyperelliptic curves. It is also shown, in Theorem 4.8, that Vojta's conjecture is sharp with D=0 on a curve C over a number field when an analogous statement holds for the curve obtained by extending the base field of C to a certain function field. 相似文献