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101.
The electrical conductivities of hydrochloric acid and potassium chloride in water have been measured in the concentration range of 3×10
–4
–10
–3
moles-dm
–3
at 0°C up to 3500 bar. The limiting molar conductance (0) for HCl increases with increasing pressure, while 0(KCl) has a maximum around 1700 bar. The excess conductance of hydrogen ion [
0
E
=0(HCl)–0(KCl)] increases with increasing pressure. Its pressure dependence indicates that the reorientation of water molecules, which is the rate-determining step in the proton jump, becomes faster at higher pressure. This anomaly is attributed to the distortion with pressure of the hydrogen bonds in water. 相似文献
102.
New chiral bidentate diphenylphospholanes were designed targeting a catalytic enantioselective aldol reaction to ketones. Ligands 5l and 5m having cis-2-butenyl and cyclopropyl groups at the linker part, respectively, were identified as effective chiral ligands for a CuF-catalyzed enantioselective aldol reaction to ketones. Catalysts prepared from CuF·3PPh3·2EtOH and these ligands produced ketone aldol products with up to 66% ee, which is promising particularly for this extremely difficult and important catalytic enantioselective carbon-carbon bond forming reaction. The enantioselectivity was strongly dependent on the linker structure. Construction of a deep chiral pocket around the copper metal with stable bidentate chelation is the key to meaningful enantioinduction. 相似文献
103.
104.
Tetsuji Kametani Yasuo Fujimoto Masakatsu Mizushima 《Journal of heterocyclic chemistry》1975,12(6):1271-1273
Reductive cyclization of 1,2,3,4-tetrahydro-6,7-dimethoxy-1-(4,5-dimethoxy-2-nitrophen-ethyl)isoquinoline (V) with triethyl phosphite gave 5,6-dihydro-2,3,9,10-tetramethoxybenzimidazo[2,1-a]isoquinoline (IX), whose structure was identified by the spectroscopic analyses by an alternative synthesis. 相似文献
105.
106.
Ferric chloride-catalyzed aerobic oxygenation of 2-halocyclohexanones in methanol to yield adipic acid dimethyl esters. 相似文献
107.
Sun Y Nakashima MN Takahashi M Kuroda N Nakashima K 《Biomedical chromatography : BMC》2002,16(5):319-326
A sensitive column switching HPLC-fluorescence detection for determination of bisphenol A (BPA) in rat brain by coupling with microdialysis was developed. A microdialysis probe was inserted into the hypothalamus of rat brain and an artificial cerebrospinal fluid was used for perfusion. BPA in brain dialysate was subjected to a fluorescent derivatization with 4-(4,5-diphenyl-1H-imidazol-2-yl)benzoyl chloride (DIB-Cl), and the excess reagent was removed by a column-switching technique. Separation was carried out on two ODS semimicro-columns with the mobile phase of acetonitrile-H(2)O-methanol-tetrahydrofuran (55:10:35:2.5, v/v) and acetonitrile-0.1 M acetate buffer (pH 3.0)-methanol (35:10:55, v/v) at a flow rate of 0.10 and 0.15 mL/min for a precolumn and a separation column, respectively. Fluorescence intensity was monitored at 475 nm with excitation of 350 nm. BPA could be sensitively detected at 0.3 ppb in 60 micro L brain microdialysate at a signal-to-noise ratio of 3. By the proposed method, concentrations of BPA in rat brain and plasma were monitored for 8 h after single i.v. or oral administration. It is proved that BPA is capable of penetrating the blood-brain barrier. The ratio of the area under the concentration-time curve of BPA in rat brain to that in blood was estimated to be about 3.0-3.8%. 相似文献
108.
Fujitani H Tanida Y Ito M Jayachandran G Snow CD Shirts MR Sorin EJ Pande VS 《The Journal of chemical physics》2005,123(8):084108
Direct calculations of the absolute free energies of binding for eight ligands to FKBP protein were performed using the Fujitsu BioServer massively parallel computer. Using the latest version of the general assisted model building with energy refinement (AMBER) force field for ligand model parameters and the Bennett acceptance ratio for computing free-energy differences, we obtained an excellent linear fit between the calculated and experimental binding free energies. The rms error from a linear fit is 0.4 kcal/mol for eight ligand complexes. In comparison with a previous study of the binding energies of these same eight ligand complexes, these results suggest that the use of improved model parameters can lead to more predictive binding estimates, and that these estimates can be obtained with significantly less computer time than previously thought. These findings make such direct methods more attractive for use in rational drug design. 相似文献
109.
Takayoshi Kobayashi Masakatsu Hirasawa Yuzo Sakazaki Hiroki Hane 《Chemical physics letters》2004,400(4-6):301-307
Ultrashort pulse lasers with 6- and 20-fs durations were utilized for phthalocyanine thin film sample to induce several vibrational modes and vibration amplitude spectra were determined by multi-wavelength measurement technique. From the spectra we could identify the electronic states, which couple to two vibrational modes with frequencies of 670 and 750 cm−1. It was shown that the vibrational amplitude profile obtained by the method can be used for providing information for the assignment of the vibrational mode. 相似文献
110.
Yamasaki S Fujii K Wada R Kanai M Shibasaki M 《Journal of the American Chemical Society》2002,124(23):6536-6537
A general and mild catalytic allylation of carbonyl compounds, applicable to aldehydes, ketones, and imines is developed using allyltrimethoxysilane as the allylating reagent. The reaction proceeds smoothly with 1-10 mol % of CuCl and TBAT in THF at ambient temperature. Mechanism studies indicated that the copper alkoxide, allylfluorodimethoxysilane, and allyltrimethoxysilane are essential to promote the reaction efficiently. Preliminary extension of the reaction to the first catalytic enantioselective allylation of ketones using an allylsilane produced the product with 61% ee from acetophenone, using a CuCl-p-tol-BINAP-TBAT catalyst (15 mol %). 相似文献