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971.
972.
The mercuration of a series of aryliminomethylferrocenes occurred predominantly in an ortho-position of the substituted ferrocenyl ring to yield 2-mercurated ferrocenylimines. The regiospecificity of this reaction suggests that the mercury is directed into the ortho-position by coordination of the mercury to imino nitrogen with subsequent electrophilic substitution. The chromatographic and spectral properties of the 2-mercurated products show the presence of an intramolecular N → Hg coordination via the five-membered ring in these molecules, which was further confirmed by the single-crystal structure analysis of 2-chloromercuro-1-[(4-methoxyphenylimino)methyl]ferrocene. 相似文献
973.
固体表面化学发光分析 Ⅰ.不渗透阻挡技术的应用和研究 总被引:2,自引:0,他引:2
本文应用不渗透阻挡技术在固体基质上保持恒定的化学发光区域,实现了固体表面化学发光分析,并对固体表面化学发光特性,发光的均匀性和重视性,固体基质的选择和纯化等方面进行了研究,测定了13种无机及生物活性物质固体表面化学发光的线性范围及检测限。由于此法克服了固体基质荧光分析和固体表面室温磷光分析的散射光背景的影响,获得了更高的信噪比和更好的检测限。 相似文献
974.
The determination of reaction paths for enzyme systems remains a great challenge for current computational methods. In this paper we present an efficient method for the determination of minimum energy reaction paths with the ab initio quantum mechanical/molecular mechanical approach. Our method is based on an adaptation of the path optimization procedure by Ayala and Schlegel for small molecules in gas phase, the iterative quantum mechanical/molecular mechanical (QM/MM) optimization method developed earlier in our laboratory and the introduction of a new metric defining the distance between different structures in the configuration space. In this method we represent the reaction path by a discrete set of structures. For each structure we partition the atoms into a core set that usually includes the QM subsystem and an environment set that usually includes the MM subsystem. These two sets are optimized iteratively: the core set is optimized to approximate the reaction path while the environment set is optimized to the corresponding energy minimum. In the optimization of the core set of atoms for the reaction path, we introduce a new metric to define the distances between the points on the reaction path, which excludes the soft degrees of freedom from the environment set and includes extra weights on coordinates describing chemical changes. Because the reaction path is represented by discrete structures and the optimization for each can be performed individually with very limited coupling, our method can be executed in a natural and efficient parallelization, with each processor handling one of the structures. We demonstrate the applicability and efficiency of our method by testing it on two systems previously studied by our group, triosephosphate isomerase and 4-oxalocrotonate tautomerase. In both cases the minimum energy paths for both enzymes agree with the previously reported paths. 相似文献
975.
Changzheng Wu Qing Yang Chao Huang Ping Yin Yi Xie 《Journal of solid state chemistry》2004,177(10):3522-3528
Pure hexagonal aluminum nitride (AlN) nanowhiskers have been successfully synthesized by directly reacting AlCl3 with NaN3 in non-solvent system at the low temperature of 450 °C for 24 h. The obtained products are characterized by X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, high-resolution transmission electron microscopy and selected area electron diffraction, which show that the obtained products are hexagonal phase AlN nanowhiskers with width from 10 to 80 nm and length up to several micrometers. The influencing factors of the formation of AlN nanowhiskers were discussed and a possible growth mechanism for AlN nanowhiskers was proposed. Additionally, the study on the corresponding optical properties and catalytic properties is also carried out. 相似文献
976.
977.
The gold nanoprisms (GNPs) have exhibited special plasmonic properties for biomedical applications because of their unique shapes and dimensions. Based on their optical performance, the NIR dye IR780 not only enabled the GNPs-based nanosystem as SERRS nanoparticles for Raman-encoded molecular imaging, but also enhanced the plasmonic photothermal property by laser irradiation. Meanwhile, the GNPs/IR780-Lyp-1 by introduction of tumor-homing peptide segment LyP-1, which presents high affinity to p32 protein, demonstrated the increased enrichment in tumor region and enhanced photothermal therapy efficacy. 相似文献
978.
Differential-pulse voltammetric determination of trace formaldehyde using magnetic microspheres and magnetic electrode 总被引:2,自引:0,他引:2
A new type of magnetic polymer microsphere containing acylhydrazine groups on the surface was synthesized. They can be reacted with formaldehyde to produce an electroactive adduct. Reduction of these derivatives following aggregation on a magnetic electrode is possible and is effective in the indirect determination of formaldehyde. The experimental conditions and electrode structure are discussed. Under the optimum conditions, it was found that the peak potential (Ep) of formaldehyde is -1.01 V (vs. Ag/AgCl). Formaldehyde in the range 1-1000 micrograms l-1 can be determined. The detection limit for formaldehyde is 0.3 microgram l-1 and the relative standard deviation for the determination of 100 micrograms l-1 formaldehyde was 2.26%. The method was applied to the determination of formaldehyde in environmental samples with satisfactory results. 相似文献
979.
A new type of magnetic polymer microspheres containing ketone groups on the surface was synthesized. It can be reacted with hydrazine to produce electroactive adduct. Reduction of this derivative that was aggregated on the magnetic electrode is possible and effective in indirect determination of hydrazine. The experimental conditions and electrode structure were discussed. Under optimum conditions, It was found that the peak potential (Ep) of hydrazine is -1.06 V (vs. Ag/AgCl). Hydrazine in the range 0.3-500 mug l(-1) can be determined. The detection limits for hydrazine is 0.1 mug l(-1). The relative standard deviation for determination of 100 mug l(-1) hydrazine was 2.43 %. The method was applied to the determination of hydrazine in water samples with satisfactory results. 相似文献
980.
Claramunt RM López C Alkorta I Elguero J Yang R Schulman S 《Magnetic resonance in chemistry : MRC》2004,42(8):712-714
The tautomerism of 5(6)-methoxy-2-([(4-methoxy-3,5-dimethyl-2-pyridinyl)methyl] sulfinyl)-1H-benzimidazole (omeprazole) was determined in solution, K(T) = 0.59 in THF at 195 K, in favor of the 6-methoxy tautomer. The assignment of the signals was made by comparison with its two N-methyl derivatives in acetone-d6 and through theoretical calculations of the absolute shieldings (GIAO/DFT/6-311++G**). 相似文献