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751.
V. V. Shcherbakov Yu. M. Artemkina T. N. Ponamareva 《Russian Journal of Electrochemistry》2008,44(10):1185-1190
Specific electric conductivity (EC) of concentrated aqueous solutions of propionic acid (PA), sodium propionate (SP), and water/PA/SP mixtures is measured in the temperature range of 15–90°C. Specific EC passes a maximum at the increase in the electrolyte concentration in the mixtures of water/PA, water/SP, and water/PA/SP containing a similar PA concentration. The maximum EC value of the aqueous PA solution at the given temperature is used as the generalizing term. It is shown that the values of reduced EC (ratio of EC and its maximum value at the given temperature) fall on a single curve in the whole studied range of temperatures and concentrations of the water/PA mixture. The EC activation energy is calculated for all the studied solutions. It is found that the EC activation energy of these solutions decreases at the temperature increase and grows at the increase of the concentration of electrolyte. 相似文献
752.
A new kind of bismuth film modified electrode to sensitively detect trace metal ions based on incorporating highly conductive ionic liquids 1‐butyl‐3‐methyl‐imidazolium hexafluorophosphate (BMIMPF6) in solid matrices at glassy carbon (GC) was investigated. Poly(sodium 4‐styrenesulfonate) (PSS), silica, and Nafion were selected as the solid matrices. The electrochemical properties of the mixed films modified GC were evaluated. The electron transfer rate of Fe(CN)64?/Fe(CN)63? can be effectively improved at the PSS‐BMIMPF6 modified GC. The bismuth modified PSS‐BMIMPF6 composite film electrodes (GC/PSS‐BMIMPF6/BiFEs) displayed high mechanical stability and sensitive stripping voltammetric performances for the determination of trace metal cations. The GC/PSS‐BMIMPF6/BiFE exhibited well linear response to both Cd(II) and Pb(II) over a concentration range from 1.0 to 50 μg L?1. And the detection limits were 0.07 μg L?1 for Cd(II) and 0.09 μg L?1 for Pb(II) based on three times the standard deviation of the baseline with a preconcentration time of 120 s, respectively. Finally, the GC/PSS‐BMIMPF6/BiFEs were successfully applied to the determination of Cd(II) and Pb(II) in real sample, and the results of present method agreed well with those of atomic absorption spectroscopy. 相似文献
753.
I. K. Petrushenko K. B. Petrushenko V. I. Smirnov B. A. Trofimov 《Russian Chemical Bulletin》2008,57(7):1461-1466
Dipyrroles with a phenylene bridge, 1,4-bis(pyrrol-2-yl)benzene, 4-(1-vinylpyrrol-2-yl)-1-(pyrrol-2-yl)benzene, and 1,4-bis(1-vinylpyrrol-2-yl)benzene,
show intense room-temperature fluorescence in solutions. Analysis of electronic absorption spectra, fluorescence spectra,
and results of B3LYP, TD B3LYP, and CIS quantum chemical calculations showed that the introduction of a bulky substituent
in position 1 of the pyrrole ring makes the ground-state structures of dipyrrolylbenzenes less planar. Excited-state geometries
of all molecules relax to more planar conformations. An increase in the probability of nonradiative transitions has little
effect on the quantum yields of fluorescence (Φf) of dipyrrolylbenzenes. Even for 1,4-bis(1-vinylpyrrol-2-yl)benzene, where the pyrrole rings deviate from the benzene ring
plane by 44°, the fluorescence efficiency remains high enough (Φf = 0.7). Substitution at nitrogen atoms has little effect on positions of fluorescence band maxima.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1433–1438, July, 2008. 相似文献
754.
以NaOH溶液快速沉淀BiCI3溶液制备了BiO(OH),研究了BiO(OH)对NaBH4还原芳香族硝基化合物的催化性能,考察了NaBH4用量对反应的影响.结果表明,在温和条件下BiO(OH)具有很高的催化活性和选择性.NaBH4和芳香族硝基化合物的摩尔比为1.04:1,在甲醇中室温反应2 h,芳香族硝基化合物主要被还原为氧化偶氮苯类化合物,收率80.4%~96.9%.该催化剂重复使用5次后活性没有明显下降.于120℃再生后,其活性与新制备催化剂相当. 相似文献
755.
采用分光光度法研究了电子给体苯巴比妥钠与π电子受体茜素红的荷移反应,建立了荷移分光光度法测定苯巴比妥钠的方法。在水溶液中,苯巴比妥钠与茜素红荷移络合物的最大吸收波长为530 nm,该络合物的组成为1∶1,表观摩尔吸光系数ε为4.43×103L.mol-1.cm-1,稳定常数为2.30×105。药物质量浓度在5~40 mg/L范围内符合比尔定律,相关系数为0.9996。当苯巴比妥钠浓度为20 mg/L时,10次测定结果的相对标准偏差为1.3%。测定了针剂中的苯巴比妥钠,加标回收率在98.9%~105%之间。 相似文献
756.
N. M. Karpiak H. A. Marshalok M. D. Fedevich I. K. Avdosieva Ya. P. Kovalskyi 《Chemistry of Heterocyclic Compounds》2008,44(11):1334-1338
Dimers of methacrolein and α-ethylacrolein have been obtained and undergo a Cannizzaro reaction to the corresponding pyran
alcohols and sodium salts of pyran acids. Their bacteriostatic, bactericidal, and fungicidal properties have been studied.
Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1639–1644, November, 2008. 相似文献
757.
758.
Ying Liu Zhongrun Yuan Sa Liu Xiupeng Zhong Yanyan Wang Renjian Xie Wenjing Song Li Ren 《Macromolecular bioscience》2023,23(11):2300153
Hydrogels are extensively investigated as biomimetic extracellular matrix (ECM) scaffolds in tissue engineering. The physiological properties of ECM affect cellular behaviors, which is an inspiration for cell-based therapies. Photocurable hyaluronic acid (HA) hydrogel (AHAMA-PBA) modified with 3-aminophenylboronic acid, sodium periodate, and methacrylic anhydride simultaneously is constructed in this study. Chondrocytes are then cultured on the surface of the hydrogels to evaluate the effect of the physicochemical properties of the hydrogels on modulating cellular behaviors. Cell viability assays demonstrate that the hydrogel is non-toxic to chondrocytes. The existence of phenylboronic acid (PBA) moieties enhances the interaction of chondrocytes and hydrogel, promoting cell adhesion and aggregation through filopodia. RT-PCR indicates that the gene expression levels of type II collagen, Aggrecan, and Sox9 are significantly up-regulated in chondrocytes cultured on hydrogels. Moreover, the mechanical properties of the hydrogels have a significant effect on the cell phenotype, with soft gels (≈2 kPa) promoting chondrocytes to exhibit a hyaline phenotype. Overall, PBA-functionalized HA hydrogel with low stiffness exhibits the best effect on promoting the chondrocyte phenotype, which is a promising biomaterial for cartilage regeneration. 相似文献
759.
Lili Zhen Kehui Liu Xuehong Ren Rong Li 《Journal of Dispersion Science and Technology》2016,37(7):941-948
The objective of this study was to develop structure–property relationship of a series of sulfosuccinic acid diester sodium salts required for industrial purposes. In this paper, three-dimensional quantum structure–activity relationship (3D-QSAR) method studies are performed to elucidate the relationship between critical micelle concentration (CMC) activity and molecular 3D structural features. Two regression models are developed by partial least squares (PLS) and genetic function approximation (GFA), respectively. The training set of PLS-QSAR model generates a correlation coefficient (R2) = 0.94539300 and sum of square of residues (S2) = 0.32764200. For the GFA-QSAR model, the training set yields R2 = 1.00000000. It is shown that the GAF method effectively improves the test accuracy significantly. Dissipative particle dynamics (DPD) mesoscopic molecular simulation method is carried out on the aggregation behavior of polyoxyethylene (n) stearyl ether sodium sulfosuccinate (PSSE-n) surfactant micelles. In the DPD simulation, water molecular (solvent) and colloidal particles are replaced by a set of DPD particles. The results demonstrated that sensitive PSSE-n molecules can assemble into special structures in specific solution concentration, such as star-shaped micelle, spherical micelle, rodlike micelle, and lamellar phase. DPD simulation can be used as an efficient method for studying the structure–property relationship of sulfosuccinic acid diester sodium salts. 相似文献
760.
Xiao-Lin Wu Yan-Ping Chu Yu-Ping Huang Zhi-Cheng Xu 《Journal of Dispersion Science and Technology》2016,37(12):1738-1744
Dilational rheological behaviors of adsorption layers of three surfactants, sodium 2-hydroxy-3,5-dioctyl benzene sulfonate (C8C8), sodium 2-hydroxy-3-octyl-5-decyl benzene sulfonate (C8C10), and sodium 2-hydroxy-3-octyl-5-dodecylbenzenesulfonate (C8C12) formed at air–water and decane–water interfaces, have been investigated as a function of concentration and frequency (0.002–0.1 Hz) by the oscillating bubble/drop method. The experimental results show that the dilational moduli of hydroxy-substituted alkyl benzenesulfonates are obviously higher than those of the common surfactants, because the interfacial interactions between alkyl chains are improved drastically by the unique arrangement of C8C8 molecules at the interface. However, the moduli at the decane–water interface are much lower than those at the surfaces because decane molecules will insert into the surfactant molecules adsorbed at the interface and destroy the interactions between alkyl chains. With an increase in the number of carbon atom of 5-alkyl, the surface dilational modulus decreases because the orientation of the surfactant molecules at the surface varies from parallel to tilt. On the other hand, the diffusion-exchange process dominates the interfacial behavior and the interfacial modulus improves with the increase in the length of the alkyl chain. 相似文献