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Toshiro Ibuka Takeshi Aoyagi Kazuko Kitada Fumio Yoneda Yoshinori Yamamoto 《Journal of organometallic chemistry》1985,287(1):c18-c22
Treatment of diethyl fumarate and triethoxycarbonylethylene with Bu2CuLi·AlCl3 led to 1,4-addition to give butylated products in high yields. In sharp contrast, diethyl maleate and tetraethoxycarbonylethylene predominantly gave the respective reduction products. The first evidence for a presumed dianionic intermediate by trapping with some electrophiles was also presented. 相似文献
73.
Brewer JH Ansaldo EJ Carolan JF Chaklader AC Hardy WN Harshman DR Hayden ME Ishikawa M Kaplan N Keitel R Kempton J Kiefl RF Kossler WJ Kreitzman SR Kulpa A Kuno Y Luke GM Miyatake H Nagamine K Nakazawa Y Nishida N Nishiyama K Ohkuma S Riseman TM Roehmer G Schleger P Shimada D Stronach CE Takabatake T Uemura YJ Watanabe Y Williams DL Yamazaki T Yang B 《Physical review letters》1988,60(11):1073-1076
74.
Swelling and deswelling kinetics was investigated for three types of cylindrical poly(N-isopropylacrylamide) (PNIPA) gels differing in crosslink density. The temperature dependence curves of the volume of the gel specimens were different from one another. One of the gel specimens was considered as a critical gel showing the continuous volume phase transition. The volume change process of the specimens after a temperature jump was examined. In the deswelling processes with temperature jumps to temperatures higher than 35 degrees C, a phase separation was observed in the gel specimens and the volume change slowed down due to the homogenization after the phase separation. The value of the diffusion constant obtained without the phase separation decreased rapidly as temperature approaches the transition temperature. The rapid decrease for the critical gel indicates the emergence of the critical slowing-down. The value of the critical exponent for the correlation length suggests that the universality class for the volume phase transition of the critical PNIPA gel belongs to the class for the classical theory. 相似文献
75.
Droplet formation in a microchannel network 总被引:21,自引:0,他引:21
A method is given for generating droplets in a microchannel network. With oil as the continuous phase and water as the dispersed phase, pico/nanoliter-sized water droplets can be generated in a continuous phase flow at a -junction. The channel for the dispersed phase is 100 microm wide and 100 microm deep, whereas the channel for the continuous phase is 500 microm wide and 100 microm deep. For given experimental parameters, regular-sized droplets are reproducibly formed at a uniform speed. The diameter of these droplets is controllable in the range from 100-380 microm as the flow velocity of the continuous phase is varied from 0.01 m s(-1) to 0.15 m s(-1). 相似文献
76.
Removing nutrients from wastewaters is important in controlling eutrophication. Processes for removing nutrients require accurate control of operational conditions, and it is necessary to monitor nutrient concentrations during the removal process. For this purpose, a simple and accurate analytical method is especially important for small-scale wastewater treatment facilities. Here, we report a simple colorimetric method for determining NH4+-N in wastewater. The method is to detect NH4+-N by a color band length formed in a minicolumn, and similar methods for heavy metals detection were reported by Morosanova et al. In this study, the length of the color band of indonaphthol dye trapped on an adsorbent in a minicolumn was linearly correlated with NH4+-N concentration in the range 1-10 mg NH4+-N l−1 under optimized conditions. This methods was developed on the basis of our previously reported color band methods for orthophosphate and nitrite determination, but the adsorbent used in this work consisted of an admixture of synthetic hydrotalcite particles and poly(vinyl chloride) particles coated with equal amounts of benzylcetyldimethylammonium chloride and biphenyl. When the method was applied to actual wastewaters, the results corresponded well with the results obtained by the standard method, and suspended solids (SS) and dissolved organic pollutants did not interfere with detection. 相似文献
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Enhancement of the Catalytic Activity of Chiral H8‐BINOL Titanium Complexes by Introduction of Sterically Demanding Groups at the 3‐Position
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Yasuki Hayashi Nobuaki Yamamura Prof. Dr. Takahiro Kusukawa Prof. Dr. Toshiro Harada 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(34):12095-12105
The activity of chiral titanium catalysts derived from H8‐BINOL ligands in the enantioselective arylation of an aldehyde with PhTi(OiPr)3 is significantly enhanced by an increase of the size of the substituent at the 3‐position. High enantioselectivity (> 90 % ee) can be obtained even at a substrate/catalyst ratio (S/C) of 800 for DTBP‐H8‐BINOL (DTBP=3,5‐di‐tert‐butylphenyl) and DAP‐H8‐BINOL (DAP=3,5‐di(9‐anthraceny)phenyl). These titanium catalysts are successfully applied to the enantioselective arylation and heteroarylation of aldehydes at a S/C ratio of 400 by using organotitanium reagents generated in situ from bromide precursors. The remarkable weakening of the intramolecular aggregation of the two ?Ti(OiPr)3 units in a DPP‐H8‐BINOL (DPP=3,5‐diphenylpheny)‐derived bis‐titanium complex is revealed by X‐ray and variable‐temperature (VT)‐NMR studies. Based on these observations, a catalytic cycle, involving the rate‐limiting aryl group transfer followed by aldehyde complexation and enantioselective arylation, is proposed to account for the high activity of the 3‐substituted H8‐BINOL catalyst system. 相似文献
80.