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991.
G.G. Bentini M. Bianconi A. Cerutti M. Chiarini G. Pennestrì C. Sada N. Argiolas M. Bazzan P. Mazzoldi 《Optics and Lasers in Engineering》2007,45(3):368
This work presents a scanning micro-interferometer, without moving parts, based on the well-known Mach-Zehnder geometry. The micro-system was obtained by using non-standard processes of planar technology on lithium niobate crystals, in particular the waveguide fabrication was obtained by using high energy ion implantation of medium light mass elements. The scanning effect without moving parts has been obtained by changing the refractive index of the optical waveguides by using electric field. The whole device is 60 mm long with a 0.5×1 mm2 cross section, weights only few grams and its power consumption lies in the milliwatt range. The performances were preliminary tested in the spectral window ranging from 0.4 to 1.0 μm. By using standard radiation sources, this micro-system demonstrated a spectral resolution suitable for detecting the characteristic spectral lines of a Xe-arc lamp on a 400 nm wide spectral window. In a further experiment we tested the performances of the microinterferometer for gas trace detection by using a calibrated NO2 optical gas cell. A sensitivity of about 10 ppb for NO2 detection, when suitable optical paths are used, was evaluated. 相似文献
992.
993.
994.
The crystal structure of strontium potassium arsenate octahydrate, SrKAsO4·8H2O, has been determined by single crystal X-ray diffraction. The crystals are tetragonal, a = 7.144(1), c = 23.613(2) Å, space group I41md (No. 109), Z = 4, V = 1205.1(1) Å3, and d
c = 2.258 g cm–3. All cations and anions in this compound are completely surrounded by water molecules. Sr2+ and K+ ions are each coordinated to eight water molecules arranged in an approximately square antiprism. The [Sr(H2O)8]2+ polyhedron shares one face of four water molecules with a [K(H2O)8]+ polyhedron forming O4-Sr-O4-K-O4 polyhedra. The O4-Sr-O4-K-O4 units are linked together through a pair of edge-sharing linkages of the outer water molecules, alternating along the a-axis and b-axis. The hydrated cation polyhedra appear to define the host lattice, which accommodates the AsO
4
3-
ion in the interstitial space. The environment of the AsO
4
3-
ion consists of 16 water molecules; each oxygen atom is the acceptor in hydrogen bonds from four water molecules. The pair distances associated with this environment may be used in investigations of the structure of hydrated
4
n-
ions in solutions. Each water molecule is coordinated to one Sr and one K, and hydrogen bonded to two O atoms of two different AsO
4
3-
ions. There is no hydrogen bonding between water molecules. 相似文献
995.
996.
997.
通过时间分辨光谱测定,发现固溶体BaFCl1-xBrx:Eu^2+荧光衰减由快衰减和慢衰减两部分组成,慢成分寿命随Br^-含量增加而减小,而快成分寿命则保持不变。该现象归因于固溶体中的不同发光中心。结合不同发射波长下的荧光寿命及激发光谱,对上述结果作了进一步的讨论。 相似文献
998.
The Ba and Ti macroconstituents as well as the impurities and dopants content (Al, Ca, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Na, Nb, Ni, P, Pb, Si, Sr, W, Zn and Zr) in a dense (> 98% theoretical) barium titanate sample have been determined by inductively coupled plasma-atomic emission spectrometry after one of these decomposition routes: (a) decomposition with HCl in a PTFE-lined pressure vessel, (b) fusion with Na2CO3 in a platinum crucible, and (c) fusion with Li2B4O7 in a graphite crucible. Matrix effects were taken into account. Detection limits for minors and trace elements were determined. High sensitivity and good precision were attained.Presented in part at the 1989 European Winter Conference on Plasma Spectrochemistry, Reutte, Austria 相似文献
999.
本文采用ICP-AES法测定钯-钡合金中常量钡。考察了基体及无机酸的存在对钡发射线强度的影响。采用标准曲线法对含量分别为0.59%和26.04%的两个试样进行了测定,结果满意。 相似文献
1000.
K. T. Priya Vadhana S. Parveen B. Ushadevi R. Selvakumar S. Sangeetha S. Vairam 《Acta Crystallographica. Section C, Structural Chemistry》2019,75(8):1091-1101
A new set of differently hydrated barium and strontium squarates, namely poly[[triaqua(μ‐1,2‐dioxocyclobut‐3‐ene‐1,2‐diolato)barium] monohydrate], {[Ba(C4O4)(H2O)3]·H2O}n ( 1 ), poly[[diaqua(μ‐1,2‐dioxocyclobut‐3‐ene‐1,2‐diolato)strontium] monohydrate], {[Sr(C4O4)(H2O)2]·H2O}n ( 2 ), and poly[[triaqua(μ‐1,2‐dioxocyclobut‐3‐ene‐1,2‐diolato)barium/strontium(0.85/0.15)] monohydrate], {[Ba0.85Sr0.15(C4O4)(H2O)3]·H2O}n ( 3 ), is reported. The study of their crystal structures indicates that all the complexes crystallize in the triclinic space group P. Complexes 1 and 3 have a rare combination of squarate units coordinated through monodentate O atoms to two different metal atoms and through two bidentate O atoms to three different metal atoms. Furthermore, they have three coordinated water molecules to give a coordination number of nine. The squarate ligands in complex 2 exhibit two different coordination modes: (i) monodentate O atoms coordinated to four different Sr atoms and (ii) two monodentate O atoms coordinated to two different metal atoms with the other two O atoms bidentate to four different Sr atoms. All the compounds decompose to give the respective carbonates when heated to 800 °C, as evidenced by thermogravimetry/differential thermal analysis (TG‐DTA), which are clusters of nanoparticles. Complexes 1 and 3 show additional endothermic peaks at 811 and 820 °C, respectively, indicating the phase transition of BaCO3 from an orthorhombic (α‐Pmcn) to a trigonal phase (β‐R3m). All three complexes have significant DNA‐binding constants, ranging from 2.45 × 104 to 9.41 × 104 M?1 against EB‐CT (ethidium bromide–calf thymus) DNA and protein binding constants ranging from 1.1 × 105 to 8.6 × 105 with bovine serum albumin. The in vitro cytotoxicity of the complexes is indicated by the IC50 values, which range from 128.8 to 261.3 µg ml?1. Complex 3 shows better BSA binding, antioxidant activity against the DPPH radical and cytotoxicity than complexes 1 and 2 . 相似文献