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101.
E. I. Basaldella J. C. Tara G. Aguilar Armenta M. E. Patiño-Iglesias E. Rodríguez Castellón 《Journal of Sol-Gel Science and Technology》2006,37(2):141-146
Samples of mesoporous silica, SBA-15, were prepared under hydrothermal conditions and Cu cations were incorporated into the
framework by two different impregnation techniques. The corresponding adsorption/desorption isotherms of propylene, propane,
and N2 were measured to evaluate the material's effectiveness in the separation of propane/propylene mixtures.
Adsorption uptake of propylene increased and that of propane decreased in Cu containing samples as compared to the uptakes
observed in undoped SBA-15 samples. It was demonstrated that the presence of Cu atoms in the adsorbent lattice led to a greater
selectivity towards propylene. Furthermore, the highest level of Cu(I) were obtained in samples prepared by equilibrium impregnation,
which in turn improved the olefin/paraffin uptake ratio. Under some working conditions, the amount of propylene adsorbed in
selected samples is totally reversible while propane uptake was negligible. 相似文献
102.
Thermally induced phase separation technique was utilized to fabricate biodegradable poly(l ‐lactic acid) (PLLA) macrocellular foams which were capable of being applied in tissue engineering. The block copolymer Pluronic F127 composed of (polyethyleneoxide)‐(polypropyleneoxide)‐(polyethyleneoxide) [(PEO)‐(PPO)‐(PEO)] was used as a porogen. Water/dioxane mixtures with different volume ratios were used as solvents. The addition of Pluronic F127 could induce an appearance of large pores (50–200 μm) besides small pores (10–20 μm) or a change from a solid–liquid phase separation to a liquid–liquid phase separation. The role of Pluronic F127 depends on the water/dioxane ratios in the PLLA/dioxane/water system. The X‐ray diffraction patterns and porosity measurement results showed that Pluronic F127 was crystallized and existed on the pore wall. The effect of Pluronic F127 on changing pore structure is attributed to the occurrence of the interaction of the lipophilic PPO blocks in Pluronic F127 with PLLA clews, consequently, this results in PLLA aggregation and early phase separation on cooling. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
103.
本文采用透射电镜(TEM)法,系统地研究了具有不同组成,不同分子量和不同形态结构的聚(苯乙烯-异戊二烯)二嵌段共聚物,并由TEM照片直接测量具有栓状,层状和有规双连续双金钢石(OBDD)结构的PS-PI二嵌共聚物的微区尺寸,讨论了其与分子量的关系。实验证明嵌段共聚物微相分离有规结构的微区尺寸大小与分子量呈2/3的关系。 相似文献
104.
Gengliang Yang Zhiwei Li Dexian Wang Zhefeng Zhang Erdong Liu Yi Chen 《Chromatographia》2002,56(7-8):515-518
Summary A high-performance liquid chromatographic method was developed for the chiral separation of a new anti-diabetic agent, N-(trans-4-isopropylcyclohexylcarbonyl)-D-phenylalanine,
and its L-enantiomer. The separation was performed on a Sumichiral OA-3300 column. Optimized mobile phase was 0.025 mol.L−1 ammonium acetate in methanol solution. UV detection was at 210 nm. Baseline chiral separation was obtained within 12 minutes.
The detection limits are 80 pg for the D-enantiomer and 120 pg for the L-enantiomer. RSD of the method was below 1% (n=5). 相似文献
105.
This paper details the analysis of the enantiomers of omeprazole, using aqueous CE coupled with MS detection. Following our
previously published work: where a non-aqueous CE–UV method was developed for omeprazole and 5-hydroxy-omeprazole; coupling
to electro-spray ionization (ESI) MS detection has now been investigated, using a sheath-flow interface for introduction.
An aqueous CE method was developed and designed to afford increased compatibility with ESI–MS detection, employing an ammonium
acetate buffer system (pH 5.8). Common partial filling methods could not be utilized to avoid the entrance of cyclodextrin
into the MS, and therefore a modified method of non-continuous-flow CE–MS was applied, with the CE separation carried out
without applied ESI voltage, before reapplying and allowing flow into the MS for data collection. A chiral CE separation of
omeprazole and 5-hydroxyomeprazole was achieved, and chiral CE resolution of omeprazole has been demonstrated using MS detection. 相似文献
106.
107.
使用手性冠醚及手性柱的HPCE和HPLC法拆分伯胺类药物对映体的对比研究 总被引:3,自引:0,他引:3
报道了在缓冲液中添加 1 8-冠 - 6 -四甲酸 (1 8C6 H4 )的高效毛细管电泳法(HPCE)对 8个含氨基的药物进行拆分 ,低 p H值 (2 .0 6 )和较高浓度的 Tris缓冲液(2 0 mmol· L- 1)可加快手性分离。用手性柱 Crownpak CR(+)的高效液相色谱(HPLC)法对与前相同的 8个含氨基药物进行拆分 ,甲醇浓度增大 ,分离度 RS值有所减小。实验结果还表明 ,使用 HPCE法拆分的各物质 RS值大于使用 HPLC法拆分相应物质的 RS值。 相似文献
108.
Thermal Properties of Hot-Stage Extrudates of Itraconazole and Eudragit E100. Phase separation and polymorphism 总被引:1,自引:0,他引:1
Six K. Leuner Ch. Dressman J. Verreck G. Peeters J. Blaton N. Augustijns P. Kinget R. Van den Mooter G. 《Journal of Thermal Analysis and Calorimetry》2002,68(2):591-601
Solid dispersions of itraconazole and eudragit E100 were prepared by hot-stage extrusion. Analysis of the physical structure
revealed the existence of different phases, depending on the manufacturing condition. Extrudates prepared at 453 K existed
as a molecular dispersion of itraconazole in eudragit E100 when the drug concentration did not exceed ca. 13% mass/mass. At
higher concentrations, a second phase consisting of pure glassy itraconazole emerged. In other dispersions prepared at 413
K, the second phase consisted of pure crystalline itraconazole. The difference can be attributed to the relation of the process-temperature
to the melting point. Heating of both dispersions induced cold crystallization. Extrudates prepared at 453 K showed comparable
behavior before and after milling, with the exception that unmilled dispersions with a drug load of ≥60% mass/mass recrystallized
upon heating into a polymorphic modification of itraconazole (T
m=431 K). Upon further heating the polymorph recrystallized to the stable crystalline form (T
m=441 K).
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
109.
微波辐照增强原煤磁分离脱硫机理探讨 总被引:5,自引:0,他引:5
采用~(57)Fe穆斯堡尔谱学方法,研究微波-磁分离法脱硫机理及微波辐照深度对脱硫率的影响。结果表明,微波选择性介质加热,可以激励煤中顺磁性黄铁矿FeS_2热解,使其转化为非化学计量的磁黄铁矿Fe_(1-x)S(0相似文献
110.
A method has been developed for the preparation of modified silica plates for high performance thin-layer chromatography (HPTLC). Some typical organosilanes were thus allowed to react in situ with the silica of Merck HPTLC-plates. This method was found to be highly reproducible, simple and cheap. Non-polar plates were prepared and compared with commercial plates from Merck, Whatman and Macherey-Nagel. Modification with cyanodecyltrichlorosilane resulted in plates that showed good coverage, efficiency and low residual silica activity. Silica modified with a multifunctional silane has different properties in different organic solvents. It will appear to be non-polar in a polar solvent and vice versa. New advantageous separation systems are thus made feasible by the presence of cyano groups on the plate. The utility of modified thin-layer plates is demonstrated by the separation of some homologues of p-hydroxybenzoic acid esters and of some polycyclic aromatic hydrocarbons. 相似文献