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991.
通过1,1’-二乙酰基二茂铁与柠檬酸三甲酰肼缩合,制成了二茂铁柠檬酰腙聚合物(Fc-NM),再在DMF中与金属(M=Cu、Co、Ni、Mn、Zn)醋酸盐配位,制成五种二茂铁酒石酰腙金属配位聚合物(Fc-NM-M)。用IR、TGA、XRD、SEM及介电常数进行表征,结果表明,在适于移动通信应用的0.2-2.0GHz频段,Fc-NM有较高的介电常数(ε‘),较低的介电损耗(ε″),将其制成倒F型微带天线有良好的缩波性能,方向图及较高的增益。因此Fc-NM作为一种天线新材料,可用于小型化、多功能化及高增益的双频微带天线。 相似文献
992.
993.
E‐Hu Liu Ting Zhou Guo‐Bin Li Jing Li Xiu‐Ning Huang Feng Pan Ning Gao 《Journal of separation science》2012,35(2):263-272
The multiple bioactive constituents in Hedyotis diffusa Willd. (H. diffusa) were extracted and characterized by high‐performance liquid chromatography/electrospray ionization tandem mass spectrometry (HPLC‐ESI‐MSn). The optimized separation condition was obtained using an Agilent ZorBax SB‐C18 column (4.6×150 mm, 5 μm) and gradient elution with water (containing 0.1% formic acid) and acetonitrile (containing 0.1% formic acid), under which baseline separation for the majority of compounds was achieved. Among the compounds detected, 14 iridoid glucosides, 10 flavonoids, 7 anthraquinones, 1 coumarin and 1 triterpene were unambiguously identified or tentatively characterized based on their retention times and mass spectra in comparison with the data from standards or references. The fragmentation behavior for different types of constituents was also investigated, which could contribute to the elucidation of these constituents in H. diffusa. The present study reveals that even more iridoid glycosides were found in H. diffusa than hitherto assumed. The occurrence of two iridoid glucosides and five flavonoids in particular has not yet been described. This paper marks the first report on the structural characterization of chemical compounds in H. diffusa by a developed HPLC‐ESI‐MSn method. 相似文献
994.
Catalytic behaviors of Co-Mn/TiO catalysts for Fischer-Tropsch synthesis 《燃料化学学报》2012,40(12):1435-1443
The 15%(Co-Mn)/TiO2,(Co/Mn=1/6) catalyst was prepared using fusion procedure and studied for the conversion of synthesis gas to C2~4 olefins. The effects of calcination conditions and operation conditions such as the H2/CO molar feed ratio at different temperatures, gas hourly space velocity (GHSV) and total reaction pressure on the catalytic performance of catalyst were investigated. The stability of the catalyst during 150 h at optimal operation conditions (t=250 ℃ H2/CO=2/1, GHSV=1 500 h-1 and p=0.3 MPa) has been investigated. It is found that this catalyst is high stable for production C2~4 olefins. Characterizations of both precursors and calcined catalysts by powder X-ray diffraction, scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) specific surface area measurement and thermal analysis methods such as thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC) show that the different preparation method influences the catalyst precursor structure and morphology. 相似文献
995.
A. Blaise C. Baravian J. Dillet L.J. Michot S. André 《Journal of Polymer Science.Polymer Physics》2012,50(5):328-337
This study presents quantitative results related to in situ investigation of the microstructural evolutions of high‐density polyethylene with deformation. These results were obtained thanks to a novel technique (IPSLT) based on the polarized light scattering transport phenomenon. The heterogeneities produced during whitening of the polymer bulk are characterized at the mesoscale level (from hundred of nanometers to a few micrometers). The technique is described as well as the identified parameters it provides, namely: the average size of the scatterers, the anisotropy developed in the medium, and the light transport length, representative of both the volume fraction and size of the heterogeneities. Results obtained during video‐controlled tensile experiments confirm those obtained previously with X‐ray microtomography. They put forward the role of morphological transformations of the amorphous/crystalline phases (especially regarding the creation of fibrillar assemblies) rather than the cavitation phenomenon. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012 相似文献
996.
Pawel W. Majewski Manesh Gopinadhan Chinedum O. Osuji 《Journal of Polymer Science.Polymer Physics》2012,50(1):2-8
Block copolymers (BCPs) offer an exciting range of structures and functions that are of potential utility in existing as well as emerging technologies. Although this is generally acknowledged, with few exceptions, viable strategies for establishing scalable and robust control of BCP microstructure are underdeveloped. Magnetic field alignment offers great potential in this regard. The physics bears much in common with electric field alignment, but the absence of dielectric breakdown concerns and the more flexible, space pervasive nature of magnetic fields make it possible to design processes for high‐throughput fabrication of well‐ordered films with appropriate materials. In this perspective, we highlight the use of magnetic fields for control of microstructure in BCPs as well as polymer nanocomposites involving anisotropic nanomaterials. A brief review of efforts to date is given. Open questions related to field‐polymer interactions and future directions for magnetic alignment of these systems are discussed. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011 相似文献
997.
《Journal of Coordination Chemistry》2012,65(14):2535-2548
Starting from cis-[Ru(dcbpyH2)2Cl2] (1), two new heteroleptic ruthenium(II) complexes, [Ru(dcbpyH2)2(L1)](NO3)2 (L1?=?2-(2′-pyridyl)quinoxaline (2), and [Ru(dcbpyH2)2(L2)](NO3)2 (L2?=?4-carboxy-2-(2′-pyridyl)quinoline (4); dcbpyH2?=?2,2′-bipyridine-4,4′-dicarboxylic acid), were synthesized and spectroscopically characterized. During the preparation of 2 and 4, the homoleptic [Ru(dcbpyH2)3]Cl2 complex (3) was isolated as a side product. Characterization includes IR and Raman spectroscopy, UV-Vis, multinuclear NMR spectroscopy, elemental, and ESI-mass spectrometric analyses. 相似文献
998.
999.
《Journal of Coordination Chemistry》2012,65(24):4304-4315
The hydrothermal reaction of Cd(II) salt with 5-[(2-methyl-1H-imidazol-1-yl)methyl]isophthalic acid (H2L) leads to the formation of a new complex [Cd(L)(H2O)] (1). While in the presence of 2,2′-bipyridine (bpy) and 1,10-phenanthroline (phen) as auxiliary ligands, complexes [Cd(L)(bpy)]?H2O (2) and [Cd(L)(phen)]?2H2O (3) were obtained. Complexes 1–3 have been characterized by single crystal and powder X-ray diffractions, IR, and elemental and thermogravimetric analyzes. As a result, complex 1 exhibits twofold interpenetrated 3-D (10,3)-a architecture, 2 displays chain structure, and 3 shows uninodal 3-connected hcb network with (63) topology. The impact of auxiliary ligands on the structures of resultant complexes is discussed. Moreover, luminescence property of 1–3 was investigated. 相似文献
1000.
《Analytical letters》2012,45(17):2661-2675
This mini-review is concerned with the characterization of synthetic and natural product pharmaceuticals by functional group analysis using electrospray ionization-ion trap mass spectrometry. Studies of the electrospray ionization–ion trap mass spectrometry behavior of selected synthetic and natural product pharmaceuticals of low molecular mass have shown certain characteristic fragmentations in that functional groups are generally cleaved from ring systems either as even electron inorganic or organic molecules such as H2O, CO, CO2, alcohols, carboxylic acids, or as odd electron entities such as methoxy and methyl. This is particularly energetically favorable in the former case with the standard heat of formation at 298.15 K of the ejected neutral molecule having a relatively high negative value. Fragmentation of pharmaceuticals involving the generation of odd electron entities such as the methyl radical is structure dependent and is to a large extent correlated with the stability of the newly formed free radical ions. The fragmentation data therefore provides useful information on the structure of these pharmaceuticals, their degradation products and metabolites. In some cases, the cleaving of functional groups may parallel the production of certain metabolites. In addition, electrospray ionization-ion trap mass spectrometry data on even and odd electron mass losses may be cross-referenced with data obtained from unknown analytes such as bioactive molecules isolated from natural sources which can then be of value in their structural characterization, assisting in the dereplication process. This mini-review on functional group analysis of selected pharmaceuticals by electrospray ionization-ion trap mass spectrometry provides examples of drug characterization following cleavage from ring systems of even electron molecules (e.g., hypnotic drugs, coumarins, phloroglucinols, and polyphenols) and odd electron entities (e.g., the alkaloid tetrandrine). Parallels between the cleaving of functional groups as even electron mass losses and the metabolic reactions of the macrocyclic antibiotic rifapentine are also discussed. 相似文献