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71.
建立了全自动QuEChERS样品制备系统结合高效液相色谱-串联质谱(HPLC-MS/MS)同时检测植物源性食品中34种农药残留的分析方法。方法利用全自动QuEChERS样品制备系统涡旋振动和离心功能,将手动QuEChERS方法中样品提取和分散固相萃取相结合;优化了操作参数及前处理步骤,在多反应监测(MRM)模式下检测,基质匹配外标法定量。从方法学验证角度对全自动QuEChERS法与手动QuEChERS法进行了比较。结果表明:该方法中大多数农药在一定范围内呈现良好的线性关系,相关系数(R2)均大于0.99,检出限为0.76~3.60 μg/kg,定量限为2.28~10.80 μg/kg,加标回收率为53.0%~125.2%,相对标准偏差(RSD)<15.9%(n=5)。该方法与手动QuEChERS法的方法验证比对结果显示差异不明显,用于植物源性食品中多农药残留检测可有效降低劳动强度和出错概率。 相似文献
72.
Dynamical Behaviour of Linear Molecular Anions in the Hydrogensulfides of Sodium, Potassium and Rubidium: Differential Scanning Calorimetry, X-ray and Neutron Diffraction Hydrogensulfides of the alkali metals M ? Na, K, Rb were prepared in autoclaves by the reaction of the corresponding metals with H2S and D2S, respectively, in the temperature range from 50°C to 150°C. Differential scanning calorimetry, X-ray and neutron diffraction methods reveal that both, the HS?-and DS?-compounds occur in three crystalline modifications with HT ? high-, MT ? medium- and LT ? low-temperature form: The temperatures and enthalpies for the changes of modifications of the H- and D-compounds are given and the atomic arrangements revealed mainly by neutron diffraction data are discussed, in relation to, for example, size of cations. 相似文献
73.
从两二酸二乙酯、氯乙酸乙酯和氯苄出发,经LiAlH4还原,合成新的二元醇,进而合成新的螺环化合物:3,9-二羟乙基-3',9'-二苯甲基-1,5,7,11-四氧杂螺[5,5]十一烷.该化合物的结构由它的氢和碳-13核磁共振谱、红外光谱和元素分析得到证明.该单体在三氟化硼乙醚络合物的作用下进行开环聚合反应.由于环上四个取代基的稳定作用,聚合物的收率比较低(产率10%左右).通过对聚合物的结构分析,提出了这一单体的阳离子开环聚合反应机理.对随聚合温度升高,聚合物中酯基/苯基的克分子比降低,以及本体聚合时得到交联聚合物等一系列现象作了探讨. 相似文献
74.
The kinetics of thermal decomposition of melted hydroxylammonium nitrate have been investigated by the rate of heat production in the temperature range 84.8–120.9°C. The decomposition proceeds with autocatalysis and up to 60 % of conversion the rate of the process increases proportionally to the square of the degree of decomposition. The initial rate is proportional to the square of the concentration of HNO3 formed due to dissociation of the salt. The activation energy of this process is 15.3±1.8 kcal/mol. It is suggested that the initial stage the process proceeds via interaction between N2O3 and NH3OH+, whereas the subsequent acceleration is due to oxidation of NH3OH+ by nitrogen oxides formed as well as by nitrous acid.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 1897–1901, November, 1993. 相似文献
75.
Single crystals of potassium iron hydrogen phosphate, KFe3(HPO4)2(H2PO4)6 · 4 H2O, were prepared hydrothermally by heating a mixture of Fe2O3, H3PO4 and K2CO3 with a small amount of water. It crystallizes monoclinic, space group C2/c (N° 15 Int. Tab.) with Z = 4 and a = 1701(2), b = 960.4(5), c = 1750(1) pm, β = 90.88(7)°. The crystal structure was solved by using 1716 unique reflections F0 > 4σ(F0) with a final wR2 value of 0.126 (SHELXL-93). The main feature of the crystal structure are layers formed by PO4-tetrahedra around the FeO6-octahedra parallel to (001). K+ and H2O molecules connect these layers. Effective Coordination Numbers (ECoN), Mean Fictive Ionic Radii (MEFIR), Charge Distribution (CHARDI) and the Madelung Part of Lattice Energy (MAPLE) are calculated for the title compound. The existence of hydrogen bonds is confirmed by these calculations. 相似文献
76.
On the Sodium Tetrahydroxoaluminate Chloride Na2[Al(OH)4]Cl The hitherto unknown compound Na2[Al(OH)4]Cl was prepared by crystallisation from a NaCl containing sodium aluminate solution. According to the X-ray single crystal investigation (tetragonal, space group P4/nmm, a = 7.541 Å, c = 5.059 Å, Z = 2) the compound represents the first example of a crystalline hydroxoaluminate with monomeric [Al(OH)4]? anions. Cl? shows a quadratic anti prismatic coordination to 4 Na+ and over hydrogen bonds to 4 O2? while Na+ is octahedrally coordinated by 4 O2? and 2 Cl? (axial). The results of the crystal structure analysis are confirmed by 27Al and 23Na MAS NMR investigations. Na2[Al(OH)4]Cl decomposes at about 200°C without intermediates under formation of β-NaAlO2 and NaCl. 相似文献
77.
本文研究了氢硼酸根(B_(12)H_(12)~(2-)、B_(10)H_(10)~(1-)、B_(11)H_(14)~-)和π-芳烃-π-环戊二烯基铁阳离子的反应,合成了36个氢硼酸π-芳烃-π-环戊二烯基铁化合物。通过元素分析和红外光谱测定确定了化合物的组成。部份化合物还作了~1H NMR鉴定。对化合物的性质,包括它们的热行为,进行了较详细的研究。DTA仪测得的结果表明,(1)当阳离子相同时,化合物的热稳定性的顺序为:[ArFeC_5H_5]_2B_(12)H_(12)>[ArFeC_5H_5]_2B_(10)H_(10)>[ArFeC_5H_5]B_(11)H_(14);(2)当氢硼酸根相同时,其热稳定性受芳环上取代基的影响。 相似文献
78.
离子液体因其熔点低、液态温域宽、蒸气压低、热稳定性高、电导率高、电化学窗口宽、结构可设计及对许多化合物的亲和性等系列性能而引起人们广泛关注。离子液体在炭材料制备、改性领域展示出了良好的前景及巨大的应用潜力,可直接作为碳源,经过高温炭化实现杂原子掺杂制备多孔炭材料;离子液体也可充当反应介质和致孔剂,将生物质转化为多孔炭材料;此外,由于离子液体与炭材料相容性较好,可以用于多孔炭材料改性制备炭复合材料。基于离子液体的炭材料在电催化、超级电容器、吸附分离及生物医学等领域具有潜在的应用价值。本文总结了基于离子液体炭材料的制备、改性及应用最新研究进展,并着重介绍了其在能源和环境相关领域的应用。 相似文献
79.
1,4-Phenylenebis(methylene) sulfonium salts were polymerized under different conditions to yield p-xylylene sulfonium salt polyelectrolytes in a broad range of molecular weights. The aqueous reaction mixture formed a reversible gel at initial monomer concentrations higher than 1.0M, but at lower concentrations it remained as an emulsion until reaction completion. The effect of reaction time on intrinsic viscosities and polymer yields for both the emulsion and the gel state is discussed. The higher yields obtained when the reaction was carried out in the presence of a water-immiscible organic solvent were apparently due to the effect of this solvent on increasing the concentration of the reactive intermediate that led to the polyelectrolyte. Both the addition of an organic solvent and the variation of the initial monomer concentrations allowed some control over the molecular weight of the polyelectrolyte formed. 相似文献
80.
Ethyl- and propylammonium nitrate are novel ionic solvents, liquid at room temperature, suitable for use as selective solvents for the isolation of analytes containing proton donor functional groups (alcohols, amines, phenols, carboxylic acids, etc.) by liquid-liquid distribution. These solvents form immiscible solvent pairs with non-polar aliphatic and aromatic hydrocarbons, ethers and alkyl halide solvents (e.g., methylene chloride, chloroform). Analytes can be recovered from the ionic solvents by back-extraction into ah organic solvent after dilution with water or pH buffer or, preferably, by extractive derivatization when gas chromatography is used for the analyses, avoiding the accumulation of salt on the column that results in poor baseline stability. Alkylation, acylation and particularly silylation are suitable methods for extractive derivatization using standard reaction conditions. Applications are presented for the isolation of polar analytes from an urban dust, shale oil and urine samples and for the determination of low-molecular-weight alcohols in gasahol and glycerol in soap. Liquid-liquid chromatographic systems with the liquid organic salt as stationary phase can be used to predict distribution constants for a particular separation and for the separation of polar solutes, particularly isomeric compounds possessing a proton donor functional group. 相似文献