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971.
Iwona Łakomska Anna Kaźnica Romana Joachimiak Andrzej Marszałek Jerzy Sitkowski Lech Kozerski Tomasz Drewa 《Chemical Papers》2011,65(3):308-314
A novel platinum(IV) coordination compound with 6-mercaptopurine (6-Hmp) has been synthesised and characterised by IR and
NMR spectroscopy. Spectroscopic parameters indicate the presence of two chelate (S-6, N-7) monodeprotonated ligands and two
chloride ions in the coordination sphere of [PtCl2(6-mp)2] · H2O (I). Two Pt(IV) coordination compounds, [PtCl2(6-mp)2] · H2O (I) and [PtCl4(dbtp)2] (II), were used in the in vivo test against B16 mouse melanoma tumours. Cytotoxic activity of compound II against the tumour cells was found to be high (LC10 = 2.6 μM, LC50 = 17.0 μM, LC90 = 58.0 μM) compared to that of cisplatin. 相似文献
972.
Phase-separation and distribution of phenyl groups for PhTES-TEOS coatings prepared on polycarbonate substrate 总被引:1,自引:0,他引:1
Yutaka Mizuta Yusuke Daiko Atsushi Mineshige Masafumi Kobune Tetsuo Yazawa 《Journal of Sol-Gel Science and Technology》2011,58(1):80-84
Phenyltriethoxysilane (PhTES) and tetraethoxysilane (TEOS) coatings [xPhTES·(100 − x)TEOS (mol%)] (x = 0 − 80) were prepared on polycarbonate (PC) substrate, and adhesion, surface hardness and distribution of phenyl groups
were studied. The coatings with more than 60 mol% of PhTES showed good adhesion (≈ 100%), and the pencil hardness of PC substrate
(4B) improved to 2B or B after the coatings. Bulk gels with the same compositions were also prepared, and distribution of
phenyl groups were estimated using fourier transform infrared (FT-IR) spectroscopy (KBr method for bulk gels and attenuated
total reflection (ATR) method for coatings). A significant difference for the distribution of phenyl groups was clearly observed
between bulk gels and coatings, suggesting PC substrate affects the distribution of phenyl groups in coatings. The adhesion
and FTIR results revealed that there is an interaction caused by π-electrons between benzene rings on PC substrate and phenyl
groups of PhTES-TEOS coatings. It was found that the adhesion was strongly correlated with the phenylsilsesquioxane networks
formed around PC substrate side. 相似文献
973.
The interactions between pentachlorophenol (PCP) and jack bean urease were studied using UV/vis absorption, CD, fluorescence,
synchronous fluorescence, and three-dimensional fluorescence spectroscopic techniques. The fluorescence data showed that the
fluorescence quenching of urease by PCP the results of the formation of a PCP–urease complex involving a hydrophobic interaction.
The distance r between the donor (urease) and acceptor (PCP) was obtained from the fluorescence resonance energy transfer. The effect of
PCP on the conformation of urease was analyzed using UV/vis absorption, synchronous fluorescence and three-dimensional fluorescence
spectroscopic techniques. The result showed that PCP can enter into the hydrophobic pocket at the interface of urease and
that the micro environments around the tyrosine and tryptophan residues were changed. 相似文献
974.
Franco Cataldo Pietro Ragni Susana Iglesias-Groth Arturo Manchado 《Journal of Radioanalytical and Nuclear Chemistry》2011,287(2):573-580
The sulphur-containing proteinaceous amino acids l-cysteine, l-cystine and l-methionine were irradiated in the solid state to a dose of 3.2 MGy. This dose corresponds to that delivered by radionuclide
decay in a timescale of 1.05 × 109 years to the organic matter buried at a depth >20 m in comets and asteroids. The purity of the sulphur-containing amino acids
was studied by differential scanning calorimetry (DSC) before and after the solid state radiolysis and the preservation of
the chirality after the radiolysis was studied by chirooptical methods (optical rotatory dispersion, ORD) and by FT-IR spectroscopy.
Although the high radiation dose of 3.2 MGy delivered, all the amino acids studied show a high radiation resistance. The best
radiation resistance was offered by l-cysteine. The radiolysis of l-cysteine leads to the formation of l-cystine. The radiation resistance of l-methionine is not at the level of l-cysteine but also l-methionine is able to survive the dose of 3.2 MGy. Furthermore in all cases examined the preservation of chirality after
radiolysis was clearly observed by the ORD spectroscopy although a certain level of radioracemization was measured in all
cases. The radioracemization is minimal in the case of l-cysteine and is more pronounced in the case of l-methionine. In conclusion, the study shows that the sulphur-containing amino acids can survive for 1.05 × 109 years and, after extrapolation of the data, even to the age of the Solar System i.e. to 4.6 × 109 years. 相似文献
975.
An amperometric sensor for the determination of indole-3-acetic acid (IAA) based on the CeCl3-DHP film modified gold electrode was developed. CeCl3 was dissolved into water in the presence of dihexadecyl hydrogen phosphate (DHP). The IAA sensor was prepared via evaporating
solvent of the CeCl3-DHP dispersion on the gold electrode surface. The amperometric response of IAA on the CeCl3-DHP film modified gold electrode was investigated. The experimental results indicate that the passivation of the electrode
due to the adsorption of the oxidation product of IAA decreases significantly at the CeCl3-DHP film modified gold electrode, in contrast to that at the bare and the DHP modified gold electrode. The experimental parameters
were optimized and an electrochemical method for the determination of IAA was established. The oxidation peak current is linearly
with the concentration of IAA from 1 × 10−7 to 2 × 10−5 mol l−1 and the detection limit is 3 × 10−8 mol l−1. The relative standard deviation of eight measurements is 3.2% for 5 × 10−7 mol l−1 IAA. The IAA in plant leaves were extracted and determined by the IAA sensor. 相似文献
976.
Isomerism, conformations, and molecular structure of a model molecule of vitamin K1 with a truncated side chain have been studied by the density functional theory calculations using B3LYP method and double-
and triple-ζ correlation consistent basis sets. The conformations of two possible (E and Z) isomers, formed by the rotations around three single C–C bonds closest to the naphthoquinone ring, have been studied. The
lowest energy conformers are stabilized by additional hydrogen bonds between hydrogen atoms of the side chain and an oxygen
atom in the naphthoquinone subunit. It is interesting to note that the structure of the energetically preferred conformer
of the E-isomer (3c) has been found to be similar to the solid state structures of phylloquinones in the photosystem I of cyanobacterium
Synechococcus elongatus. The excited electronic states of two lowest energy conformers have also been investigated. 相似文献
977.
Enthalpies (Δisom
H
(g)o), Gibbs free energies (Δisom
G
(g)o), and equilibrium constants (log K
isom) for the trans → cis isomerization of various 3,3′-, 4,4′-, and 5,5′- disubstituted 2,2′-diphenoquinones with a range of electron withdrawing
and releasing moieties (methyl, fluoro, chloro, bromo, trifluoromethyl, and amino) were calculated in the gas phase and in
the solvent phase (n-hexane, benzene, n-octanol, acetonitrile, and water). In the gas phase, the trans isomer of the parent and all substituted 2,2′-diphenoquinones is predicted to be more thermodynamically stable than the cis configuration, with log K
isom ranging from −2.8 to −7.0. For all compounds, increasing solvent polarity/proticity progressively favors shifting the cis/trans equilibrium towards greater contributions of the cis configuration and substantially increases the log K
isom by up to 5.1 units relative to the gas phase. In polar protic and polar aprotic solvents, the estimated log K
isom ranges as low as −0.4, indicating significant populations of the cis isomers should be present. The findings support the polar solvent phase mechanistic predictions for a cis configuration of 2,2′-diphenoquinones participating in the thermal transformation of trans-2,2′-diphenoquinones to oxepino[2,3-b]benzofurans. With limited exceptions for some amino derivatives, the cis-2,2′-diphenoquinone to oxepino[2,3-b]benzofuran isomerization is expected to be thermodynamically favorable for all substituents/phases
under consideration. The cis-2,2′-diphenoquinone to oxepino[2,3-b]benzofuran rearrangement is predicted to become less thermodynamically favored with
increasing solvent polarity/proticity. 相似文献
978.
Metabolome analysis of human cerebrospinal fluid (CSF) is challenging because of low abundance of metabolites present in a
small volume of sample. We describe and apply a sensitive isotope labeling LC-MS technique for qualitative analysis of the
CSF metabolome. After a CSF sample is divided into two aliquots, they are labeled by 13C-dansyl and 12C-dansyl chloride, respectively. The differentially labeled aliquots are then mixed and subjected to LC-MS using Fourier-transform
ion cyclotron resonance mass spectrometry (FTICR MS). Dansylation offers significant improvement in the performance of chromatography
separation and detection sensitivity. Moreover, peaks detected in the mass spectra can be readily analyzed for ion pair recognition
and database search based on accurate mass and/or retention time information. It is shown that about 14,000 features can be
detected in a 25-min LC-FTICR MS run of a dansyl-labeled CSF sample, from which about 500 metabolites can be profiled. Results
from four CSF samples are compared to gauge the detectability of metabolites by this method. About 261 metabolites are commonly
detected in replicate runs of four samples. In total, 1132 unique metabolite ion pairs are detected and 347 pairs (31%) matched
with at least one metabolite in the Human Metabolome Database. We also report a dansylation library of 220 standard compounds
and, using this library, about 85 metabolites can be positively identified. Among them, 21 metabolites have never been reported
to be associated with CSF. These results illustrate that the dansylation LC-FTICR MS method can be used to analyze the CSF
metabolome in a more comprehensive manner. 相似文献
979.
Voinov VG Deinzer ML Beckman JS Barofsky DF 《Journal of the American Society for Mass Spectrometry》2011,22(4):607-611
Recently, we demonstrated that a radio-frequency-free electromagnetostatic (rf-free EMS) cell could be retrofitted into a
triple quad mass spectrometer to allow electron-capture dissociation (ECD) without the aid of cooling gas or phase-specific
electron injection into the cell (Voinov et al., Rapid Commun Mass Spectrom 22, 3087–3088, 2008; Voinov et al., Anal Chem 81, 1238–1243, 2009). Subsequently, we used our rf-free EMS cell in the same instrument platform to demonstrate ECD occurring in the same space
and at the same time with collision-induced dissociation (CID) to produce golden pairs and even triplets from peptides (Voinov
et al., Rapid Commun Mass Spectrom 23, 3028–3030, 2009). In this report, we demonstrate that ECD and CID product-ion mass spectra can be recorded at high resolution with flexible
control of fragmentation processes using a newly designed cell installed in a hybrid Q-TOF tandem mass spectrometer. 相似文献
980.
Hee-Soo Kim Byoung-Ho Lee Sena Lee Hyun-Joong Kim John R. Dorgan 《Journal of Thermal Analysis and Calorimetry》2011,104(1):331-338
This study examined the interfacial adhesion, mechanical, and thermal properties of compatibilizing agent-treated and non-treated
biocomposites as a function of the type of compatibilizing agent. The tensile strength, interfacial adhesion, and heat deflection
temperature (HDT) of maleic anhydride-grafted poly(butylene succinate) (PBS-MA) and maleic anhydride-grafted poly(lactic acid)
(PLA-MA)-treated biocomposites are greater than those of untreated maleic anhydride-grafted poly(styrene-b-ethylene-co-butylene-b-styrene)
triblock copolymer (SEBS-MA) and maleic anhydride-grafted polypropylene (MAPP)-treated biocomposites. The storage modulus
(E′) values and the tan δmax temperatures (T
g) of PBS-MA and PLA-MA-treated biocomposites were slightly higher than that of the untreated biocomposites. 相似文献