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991.
使用密度泛函理论B3LYP方法和6-31G(d,p)、6-31+G(d,p)、6-311G(d,p)及6-311+G(d,p)基组,分别对2-C5H10+和1-C5H10+的各种构象进行了几何构型优化,并用B3LYP/6-311G(d,p)进行了频率分析计算.计算预言1-C5H10+具有非平面构型,与以往报导的从头算计算结论相反.在两个自由基阳离子的各种构象的B3LYP几何构型上,进行了B3LYP和UMP2(full)方法的超精细偶合常数计算,得到了比以往更好的结果. 相似文献
992.
负载型纳米TiO2光催化降解活性艳红X-3B染料 总被引:21,自引:0,他引:21
光催化氧化;负载型纳米光催化剂;负载型纳米TiO2光催化降解活性艳红X-3B染料 相似文献
993.
《Analytical letters》2012,45(2):223-234
Abstract A new method is described that facilitates determining the efficiency of air sampling traps to adsorb and thermally desorb volatile organic compounds. A known volume of a liquid standard of volatile organic compounds is vaporized into an air stream, a fraction of which is collected on an air sampling trap. This trap is subsequently thermally desorbed and analyzed using a GC/FID. The efficiency of the trap to adsorb and thermally desorb each compound tested is calculated. 相似文献
994.
《Analytical letters》2012,45(15):2707-2715
Abstract A simple and efficient HPLC analysis method has been developed to simultaneously analyse complicated multi-vitamin preparations, including vitamin B complexes, vitamin C, orotic acid, methionine, calcium pantothenate, nicotinamide, biotin, folic acid and rutin, without using expensive ion pairing reagent. Diode array detector and adjustment of the mobile phase to pH 5.6 are required in the study. This method has been validated with good linearity, reproducibility, recovery and accuracy for analysis of commercial multi-vitamin products. 相似文献
995.
《Analytical letters》2012,45(15):3111-3130
ABSTRACT Compound independent calibration (CIC) can be used to measure stable isotopically labeled molecules and their metabolites. This study was designed to demonstrate that gas chromatography coupled to atomic emission detection and CIC are useful analytical tools for the specific and quantitative determination of 13C and 15N labeled caffeine and its metabolites. These labeled compounds can be measured by monitoring either 13C or 15N atomic emission lines and using only one calibration function from one of the analytes. This method can be helpful when it is difficult or impossible to obtain an authentic reference material, which is often the case in metabolic studies. 相似文献
996.
Elton A. S. Castro Ricardo Gargano João B. L. Martins 《International journal of quantum chemistry》2012,112(16):2828-2831
In this work, we present a theoretical study of interaction of benzene with kaolinite and an analysis of the vibrational spectra, electrostatic potential maps, and self consistent field (SCF) orbitals. B3LYP and MP2 benzene–kaolinite results indicate a preferential interaction of benzene on kaolinite octahedral surface. Population analysis indicates that the atoms modified their charges when the monoaromatic molecule and clay mineral are close to tetrahedral and octahedral surface of kaolinite, which suggests that the adsorbed molecule becomes slightly positive. Infrared vibrational data show the reduction in the band frequencies related to the kaolinite external hydroxyls, indicating a weak interaction of benzene with clay mineral. It also was verified, from the potential electrostatic maps, a change in electron density in both benzene and kaolinite. Electron localization function analysis was also carried out for this interaction. © 2011 Wiley Periodicals, Inc. 相似文献
997.
《Analytical letters》2012,45(17):2751-2761
Quinoline-appended rhodamine B thiohydrazide based fluorescent probe was designed and applied in fluorescent detections of mercury ions in both aqueous solution and living cells. The signal change of the probe is based on a specific metal ion induced reversible ring-opening mechanism of a rhodamine B thiohydrazide. The probe exhibits a dynamic response concentration range for Hg2+ from 1.0 × 10?8 to 1.0 × 10?5 M with a detection limit of 8.5 × 10?9 M. The fluorescent probe is pH independent in medium condition and exhibits high selectivity over other common metal ions. 相似文献
998.
《Analytical letters》2012,45(5):898-907
A new aptamer-based fluorescence nanoprobe for potassium ion (K+) has been developed. The nanoprobe employs gold nanoparticles (AuNPs) as the sensing platform and Rhodamine B as the fluorescence indicator. Aptamer acts as the switch of fluorescence signal of Rhodamine B. In the presence of K+, aptamer departs from AuNPs as a result of the formation of G-quartets with K+, leading to the decrease of fluorescence signals. Under the optimum conditions, the limit of detection (LOD) for K+ is as low as 3.8 nM. The proposed method was successfully applied in the determination of K+ in human saliva sample. 相似文献
999.
碲钨杂多酸—丁基罗丹明B超高灵敏显色反应的研究 总被引:5,自引:0,他引:5
聚乙烯醇存在下,碲与钨酸钠形成碲钨杂多酸,继而丁基罗丹明B形成离子缔合物。 相似文献
1000.
A general method for the synthesis of 5-substituted indolizidines based on intramolecular cyclization oftrans- andcis-2-allyl-6-R-1,2,3,6-tetrahydropyridines, obtained from pyridine and triallylborane, has been elaborated. The closure of the
five-membered ring is carried out by hydroboration-oxidation followed by cyclization of the resulting δ-amino alcohols in
the presence of the Ph3P−CBr4−Et3N system. (Pr2BH)2 and Pr3B are used as the hydroborating reagents, and H2O2 in an acid medium is used for the oxidation of 2-[3-(dipropylboryl]-Δ2-piperideines formed. This method has been used for the synthesis of two natural alkaloids: indolizidine 209D (cis-5-hexylindolizidine) and itstrans-isomer were prepared fromcis- andtrans-2-allyl-6-hexyl-1,2,3,6-tetrahydropiridine, respectively; indolizidine 167B andtrans-5-propylindolizidine were synthesized fromcis- andtrans-2,6-diallyl-1,2,3,6-tetra-hydropyridine, respectively.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 971–979, May, 1998. 相似文献