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991.
阻抑动力学光度法测定痕量间二硝基苯 总被引:2,自引:1,他引:2
在盐酸介质中,痕量间二硝基苯能灵敏地阻抑Fe^3 催化高碘酸钾氧化孔雀绿的反应。研究了该阻抑反应的最佳条件及动力学参数,建立了测定痕量间二硝基苯的新方法,间二硝基苯的线性范围为0.0-10.0μg/L,检出限为1.8μg/L。该法灵敏、简便,选择性好,用于环境水样中间二硝基苯的测定,结果准确。 相似文献
992.
Aziridines and epoxides were reacted with diphenyl diselenide in the presence of a stoichiometric amount of (n-Bu)3P, respectively, giving β-amino- or β-hydroxy selenides in moderate to excellent yields under mild conditions. In the reactions the (n-Bu)3P might act as a reductant though it was a nucleophilic catalyst in other similar ring-opening reactions. 相似文献
993.
Xiancui Zhu Yuzhe Jiang Jun Chen Shaowu Wang Zeming Huang Shan Zhu Xu Zhao Wenrun Yue Jun Zhang Weikang Wu Xiangyang Zhong 《中国化学》2020,38(5):478-488
A series of dinuclear rare‐earth metal alkyl complexes {[μ‐η2:η1:η1‐3‐( L NCH)(CH2SiMe3)Ind]RE(CH2SiMe3)(THF)}2 ( L 1 = 2‐tBuC6H4, RE = Y, Gd, Dy, Er, Yb; L 2 = 2,4,6‐Me3C6H2, RE = Dy, Er; Ind = indolyl) and {[μ‐η2:η1:η1‐3‐( L NCH2)Ind]RE(CH2SiMe3)(THF)}2 ( L 1, RE = Y, Dy, Er, Yb; L 2, RE = Er, Yb) bearing 3‐arylamido functionalized indolyl ligands having diverse bonding modes with metal ions were synthesized either by the insertion reaction of the imino group to the RE—C bond or by the alkane elimination reaction. In the preparation of above complexes, rare‐earth metal alkyl complexes [μ‐η5:η1:η1‐3‐( L 2NCH)(CH2SiMe3)Ind]Gd(CH2SiMe3)(THF)}2 with a μ‐η5:η1:η1 coordination mode to the gadolinium ion and {[μ‐η3:η1:η1‐3‐( L 2NCH2)Ind]Dy(CH2SiMe3)(THF)}2 with a μ‐η3:η1:η1 coordination mode to the dysprosium ion were unexpectedly isolated. The reactions of 3‐( L 2N=CH)Ind with Er(CH2SiMe3)3(THF)2 at room temperature, generated a tetranuclear imino‐indolyl erbium intermediate {[μ‐η1:η1‐3‐( L 2N=CH)Ind]Er(CH2SiMe3)2(THF)}4, which can transform into the amido functionalized indolyl erbium complex in hot toluene. Moreover, the reactivities of the newly synthesized ytterbium complex with N‐heterocyclic compounds were investigated, affording the corresponding products of the mixed pyridyl‐indolyl, imidazolyl‐indolyl, and ortho‐metalated complexes. The yttrium complexes showed a high regioselectivity and steroselectivity for the isoprene polymerization with 1,4‐trans selectivity up to 91.7% and 1,4‐cis selectivity up to 96.1% in the presence of cocatalysts, respectively. 相似文献
994.
995.
A novel coordination polymer of [Ca(2-OPA)2(H2O)2]n (2-OPA-=2-oxo-1(4H)-pyridineacetate anion) was synthesized and characterized by elemental analysis, IR, TG and single crystal X-ray diffraction. The title complex crystallizes in orthorhombic with space group Pna21, a=0.799 96(16) nm, b=0.823 77(16) nm, c=2.415 3(5) nm, V=1.591 6(6) nm3, Z=4, R=0.030 3, wR=0.070 0. The Ca atom is eight-coordinated by six O atoms of four 2-OPA- ligands and two water molecules, and displays a dodecahedron coordination geometry. Each 2-OPA- ligand bridges two adjacent Ca atoms, forming a infinite chain along the a direction. The Ca…Ca distance is 0.4102 2(8)nm. A two-dimensional supramolecular framework is further constructed by the hydrogen bonds and the weak π-π interactions. The results of TG analysis show the chain structure of the title complex was stable under 297.5 ℃. CCDC: 251669. 相似文献
996.
采用液-液萃取结合GC/MS选择离子的方法,建立了人尿中8种合成麻醉镇痛剂的分析方法,讨论了回收率和检测限问题,并成功地用于实际尿样检测。 相似文献
997.
998.
Keggin结构的磷钨钒稀土四元杂多配合物对过氧化氢分解的催化作用 总被引:4,自引:0,他引:4
在磷钨钒稀土四元杂多配合物中,由于V原子的使用,使其对H2O2分解的催化活性显著增加。因配合物中心原子稀土元素不同。催化活性也随之变化,其活化能与三阶稀土离子的电离能有密切关系。动力学曲线为S型。实验证明,在反应过程中有反应活性中间体生成。 相似文献
999.
Synthetic nylon-6 single molecular mass oligomers were studied by matrix-assisted laser desorption/ionization (MALDI) and electrospray ionization (ESI) mass spectrometry. These oligomers, considered as model compounds for the study of nylon-6 polymers, gave good mass spectrometric results using both MALDI and ESI. In spite of the gentle nature of both techniques, the MALDI and ESI spectra showed evidence of end-group cleavage from the oligomer chains. MALDI-MS was found to give similar fragmentation patterns for all of the oligomer samples. An increase in doubly charged ion signals with increasing oligomer mass was observed in the ESI mass spectra, as was end-group fragmentation. Signals from oligomer clusters were observed in ESI-MS for the dimer, tetramer and hexamer, most likely due to non-covalent bonding among the low-mass oligomer molecules. 相似文献
1000.