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71.
The cellular mechanism based on P-glycoprotein (PGP) for its drug pump function has become very important in multidrug resistance (MDR) research. A method has been established to characterize PGP on single K562 cell by coupling capillary electrophoresis with laser induced fluorescence detection. A permeable intact cell after the immunoassay binding with fluorescence labeling antibody was injected into the capillary and directly separated without lysis. It was found that once 5-10 optional cells were detected in batch, the PGP amount on this cell line could be outlined and calculated clearly. The PGP amount on K562 MDR cell line is 3.88 times higher than that on K562 sensitive cell line. These two cell lines with immunoassay binding were also analyzed by injection of multi-cells in order to improve the throughput. A resistance factor so called multidrug resistance multiple (MRM) was introduced to evaluate the MDR difference between cell lines. The MRM values of the cell line K562 measured by single cell analysis are well correlated with those by flow cytometry, which also prove the validity of our method in single cell analysis for the possibility of cancer diagnosis, pharmacokinetics and drug screening in future. 相似文献
72.
A highly sensitive and selective catalytic adsorptive cathodic striping procedure for the determination of trace germanium is presented. The method is based on adsorptive accumulation of the Ge(IV)‐gallic acid (GA) complex onto a hanging mercury drop electrode, followed by reduction of the adsorbed species. The reduction current is enhanced catalytically by addition of vanadium(IV)‐EDTA. The optimal experimental conditions include the use of 0.03 mol/L HClO4 (pH1.6), 6.0×10?3 mol/L GA, 3.0×10?3 mol/L V(IV), 4.0×10?3 mol/L EDTA, an accumulation potential of ?0.10 V(vs. Ag/AgCl), an accumulation time of 120 s and a differential pulse potential scan mode. The peak current is proportional to the concentration of Ge(IV) over the range of 3.0×10?11 to 1.0×10?8 mol/L and the detection limit is 2×10?11 mol/L for a 120 s adsorption time. The relative standard deviation at 5.0×10?10 mol/L level is 3.1%. No serious interferences were found. The method was applied to the determination of germanium in ore, mineral water and vegetable samples with satisfactory results. 相似文献
73.
(Z)-3-丁烯基苯酞和它的衍生物广泛地存在于微形科植物,如当归、川芎等,这些植物有些是重要的中药材。(Z)-3-丁烯基-4,5-二羟基苯酞是(Z)-3-丁烯基苯酞的类似物;它对前列腺素F2α具有抑制作用。本文以3,4-二甲氧基苯甲醇(2)或价廉易得的胡椒醇(6)为起始原料,分别经四步反应顺利地合成了(Z)-3-丁烯基-4,5羟基苯酞(1)。和一步是本方法的关键,即利用杂原子诱导的区域选择性的芳环 相似文献
74.
Jinmao You Xiangming Chen Xianen Zhao Yourui Suo Honglun Wang Yulin Li Jing Sun 《Chromatographia》2006,63(7-8):337-343
A pre-column derivatization method for the sensitive determination of amines using the labeling reagent 1,2-benzo-3,4-dihydrocarbazole-9-isopropyl
chloroformate (BCIC-Cl) followed by high-performance liquid chromatography with fluorescence detection has been developed.
Identification of derivatives is carried out by high performance liquid chromatography/atmospheric pressure chemical ionization
(LC-APCI-MS-MS). The chromophore of 2-(9-carbazole)-ethyl chloroformate (CEOC) reagent is replaced by 1,2-benzo-3,4-dihydrocarbazole-9-isopropyl
functional group, which results in a sensitive fluorescence derivatizing reagent BCIC-Cl. BCIC-Cl can easily and quickly label
amines. Derivatives are stable enough to be efficiently analyzed by high-performance liquid chromatography and show an intense
protonated molecular ion corresponding m/z [MH]+ under APCI in positive-ion mode. The collision-induced dissociation of protonated molecular ion formed a product at m/z 260 corresponding to the cleavage of CH2-OCO bond. Studies on derivatization demonstrate excellent derivative yields over the pH 9.0–10.0. Maximal yields close to
100% are observed with a 3 to 4-fold molar reagent excess. In addition, the detection responses for BCIC derivatives are compared
with those obtained using CEOC and FMOC as derivatization reagents. The ratios of IBCIC/ICEOC and IBCIC/IFMOC are, respectively, 1.23–3.14 and 1.25–3.08 for fluorescent (FL) responses (here, I is relative fluorescence intensity). Separation of the derivatized amines had been optimized on reversed-phase Eclipse XDB-C8 column. Detection limits are calculated from 1.0 pmol injection, at a signal-to-noise ratio of 3, are 10.6–37.8 fmol. The
mean interday accuracy ranges from 94 to 105% for fluorescence detection with the largest mean %CV<7.5. The mean interday
precision for all standards is < 6.0% of the expected concentration. Excellent linear responses are observed with coefficients
of > 0.9997.
Revised: 12 December 2005 and 13 Febrauary 2006 相似文献
75.
Guo Jin-xin Sun Si-xiu Zhu Rong-xiu Yin Zhi-lei Yu Hai-yun Li Da-zhi Zhang Wei-min Xu Xian-gang Sun Xuan Shao Hua 《Journal of Radioanalytical and Nuclear Chemistry》2004,261(1):221-224
The 222Rn emanation fraction (EF) released from the technically enhanced naturally occurring radioactive material (TE-NORM) wastes
at certain sites of petroleum and gas production was determined. The samples were analyzed by γ-ray spectrometry to determine
the activity concentration of the 226Ra content, of which the 222Rn emanation fraction was calculated. The results showed that the 222Rn emanation fraction differs in the oil and gas production sites and it is independent of the activity concentration of 226Ra.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
76.
The CHCl3 extract of dried roots of Hemerocallis fulva (L.) L. afforded a novel diterpene named hemerocallal A ( 1 ), which is the second reported naturally occurring diterpene with a trans‐bicyclo[5.1.0]octane system. The BuOH extract afforded a new glycoside named hemerocalloside ( 2 ). Their structures were established on the basis of spectroscopic and chemical studies. 相似文献
77.
The conversion of phosphoenolpyruvate (PEP) to phosphonopyruvate (P-pyr) is catalyzed by PEP mutase via a dissociative mechanism. In this work, we investigate the uncatalyzed reaction using ab initio methods, density functional theory, and the semiempirical MNDO/d method. Comparisons of geometries and relative energies of stationary points (minima and transition states) with density functional results indicate that the semiempirical method is reasonably accurate. Solvent effects are examined using implicit solvent models, including the recently extended smooth conductor-like screening model. Due to the large negative charge carried by the system, solvation is found to drastically alter the location and energy of stationary points along the dissociative reaction pathways. The influence of substituting a nonbridging phosphoryl oxygen by sulfur (thio effects) was also investigated. Implications of these results for the enzymatic reaction are discussed. 相似文献
78.
The liquid chromatographic enantiomer separation of N-fluorenylmethoxycarbonyl (FMOC) protected alpha-amino acids and their ethyl ester derivatives was performed on polysaccharide-derived chiral stationary phases, Chiralcel OD, Chiralpak AD, and Chiralpak AS. In general, Chiralcel OD and Chiralpak AD showed good performance for resolution of N-FMOC alpha-amino acids and their ethyl esters, respectively. All investigated N-FMOC alpha-amino acid enantiomers were baseline separated on Chiralcel OD or Chiralpak AD, whereas N-FMOC alpha-amino acid ethyl ester enantiomers were baseline resolved (alpha = 1.15-3.03) on Chiralpak AD, except for two analytes. The L-enantiomers of all examined FMOC alpha-amino acid ethyl ester derivatives are preferentially retained on Chiralpak AD, while the elution orders of the other enantiomer separations are not consistent. 相似文献
79.
Meyers CY Chan-Yu-King R Hua DH Kolb VM Matthews WS Parady TE Horii T Sandrock PB Hou Y Xie S 《The Journal of organic chemistry》2003,68(2):500-511
Most alkyl phenyl sulfones are readily alpha-chlorinated with CCl(4) and alpha-brominated with CBrCl3 in KOH-t-BuOH via radical-anion radical pair (RARP) reactions. While isopropyl mesityl sulfone (4) is easily alpha-chlorinated with CCl(4), it was completely recovered when treated with the more reactive CBrCl3. Subsequent investigations showed the latter result to be due to the poor acidity of 4 together with the rapid depletion of CBrCl3 and KOH by their reaction with each other, and led to a variety of other important results. 4-Hydroxyphenyl isopropyl sulfone (6) is unreactive with either CCl4 or CBrCl3 in KOH-t-BuOH, its phenoxide anion strongly reducing the electronegativity of the sulfonyl group, thereby inhibiting alpha-anion formation. This effect is reversed by the electron-withdrawing influence of two alpha-phenyls, so that benzhydryl 4-hydroxyphenyl sulfone (8) is readily alpha-halogenated in KOH-t-BuOH with CCl4 or CBrCl3. On further contact with KOH-t-BuOH the alpha-halogenated sulfones from 8 are decomposed into benzophenone and phenol. While the alpha-halogenated derivatives of 4-methoxyphenyl benzhydryl sulfone (9) are stable to base, they are decomposed even under mildly acidic conditions into 4-methoxyphenyl 4-methoxybenzenethiolsulfonate (9c), phenol, and benzophenone. Mono-alpha-halogenation of benzyl phenyl sulfone (10) enhances the rate of the subsequent halogenation, so that alpha,alpha-dihalogenation is attained while much substrate is still present and the mono-alpha-halogenated product is not detected. The ease of reductive debromination of alpha-bromo sulfones with Cl3C- was correlated with the stability of the formed alpha-anions, explaining the success with alpha-bromobenzylic sulfones but failure with alpha-bromoalkyl sulfones. In the presence of air and the absence of competing halogenation, formation of the alpha-anions of alkyl aryl sulfones is quickly accompanied by oxidative cleavage by atmospheric O2, leading to the formation of arenesulfonyl alcohols, arenesulfonyl halides, and haloarenes. 相似文献
80.
The mechanism of the SO2 + HO2 reaction was studied theoretically for the first time. Three product channels were revealed, namely, O2 + HOSO, O2 + HSO2, and OH + SO3. The O2 + HOSO channel dominates the reaction under combustion conditions. A five-member-ring complex [SO2–HO2] exists at the entrance of the reaction. The structure and binding energy (De and D0) of the SO2–HO2 complex have been calculated. In view of D0 = 21.2 ± 2.0 kJ mol−1, the SO2–HO2 complex should be stable at low temperature. The infrared spectra and frequency shifts were calculated for both SO2–HO2 and SO2–DO2, and compared with the available experimental data. 相似文献