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911.
Two new compounds, [Ni2(L1)(Py)6]Py·CH3OH(1) and [Ni3(L2)2(Py)4]·2DMF(2)(H4L1=N,N'-bisalicyl- bisthiocarbamide; H3L2=3-hydroxyl-2-naphthalene thiosemicarbazide; Py=pyridine; DMF=dimethyl fumarate), based upon two thiosemicarbazone ligands have been obtained and characterized by elemental analysis, Fourier transform infrared(FTIR) and X-ray diffraction(XRD). Compound 1 possesses a binuclear cluster, in which the bisalicylbisthiocarbamide acts as a hexadentate bridge. Compound 2 exhibits a linear trinuclear cluster with the triply-deprotonated ligand acting as pentadentate bridge. C―H···O, C―H···π and C―H···S weak interactions further link these molecules to form interesting supramolecular networks. 相似文献
912.
基于环糊精的靶向药物传递系统 总被引:1,自引:0,他引:1
癌症等恶性增殖疾病的靶向治疗有赖于靶向药物传递系统(targeted drug delivery system,TDDS)的开发。环糊精具有低毒、易修饰等优良性质,并可通过与药物分子形成包合物而提高药物的溶解性、稳定性、安全性和生物利用度等,因而具有成为优秀药物载体的潜力。环糊精不仅可以以其本身或修饰环糊精的形式充当载体,还可通过聚轮烷、阳离子聚合物或纳米粒等形式构建有效的药物载体。肿瘤或人体某些病变部位的细胞表面存在过度表达的生物受体如叶酸受体、去唾液酸糖蛋白受体、透明质酸受体、转铁蛋白受体和整合素受体等,可以与其相应的配体产生特异性识别。用适当的化学方法将配体分子如叶酸、单糖或寡糖、透明质酸、转铁蛋白及RGD肽等键接在基于环糊精的载体上,可形成具有靶向性质的药物载体,进而与药物分子一起构筑靶向药物传递系统。这种药物传递系统不仅针对于化学治疗药物,在核酸传递中也得到了丰富的应用。本文综述了基于环糊精的靶向药物传递系统的靶向机理及最新研究进展,并对其发展前景作了展望。 相似文献
913.
报道了3个β-羟亚胺配体(2,6-emPr2C6H3)N=C(Ph)CH2CH(Ph)OH(1a), (2,6-emPr2C6H3)N=C·(Ph)CH2C(Ph)2OH(1b)和(2,6-emPr2C6H3)N=C(Ph)CH2C(C12H8)OH(1c)及其二(β-羟亚胺)二氯化钛配合物[(2,6-emPr2C6H3)N=C(Ph)CH2CH(Ph)O]2TiCl2(2a), [(2,6-emPr2C6H3)N=C(Ph)CH2C(Ph)2O]2·TiCl2(2b)和[(2,6-emPr2C6H3)N=C(Ph)CH2C(C12H8)O]2TiCl2(2c)的合成, 并对其结构进行了表征. 在助催化剂甲基铝氧烷(MAO)作用下, 以化合物2b为主催化剂, 研究了Al/Ti摩尔比、 反应时间、 温度和聚合压力等对乙烯聚合的影响, 发现该催化体系在较宽的反应条件下均可得到很高分子量的聚乙烯, 熔点均在140℃左右. 以化合物2a~2c为主催化剂对乙烯进行催化聚合, 发现在β碳位上取代基的立体位阻对催化剂活性有很大影响. 当化合物2b上引入2个苯基取代基时, 催化剂显示出最佳催化活性. 相似文献
914.
Solid energy calibration standards for P K‐edge XANES: electronic structure analysis of PPh4Br 下载免费PDF全文
Anastasia V. Blake Haochuan Wei Courtney M. Donahue Kyounghoon Lee Jason M. Keith Scott R. Daly 《Journal of synchrotron radiation》2018,25(2):529-536
P K‐edge X‐ray absorption near‐edge structure (XANES) spectroscopy is a powerful method for analyzing the electronic structure of organic and inorganic phosphorus compounds. Like all XANES experiments, P K‐edge XANES requires well defined and readily accessible calibration standards for energy referencing so that spectra collected at different beamlines or under different conditions can be compared. This is especially true for ligand K‐edge X‐ray absorption spectroscopy, which has well established energy calibration standards for Cl (Cs2CuCl4) and S (Na2S2O3·5H2O), but not neighboring P. This paper presents a review of common P K‐edge XANES energy calibration standards and analysis of PPh4Br as a potential alternative. The P K‐edge XANES region of commercially available PPh4Br revealed a single, highly resolved pre‐edge feature with a maximum at 2146.96 eV. PPh4Br also showed no evidence of photodecomposition when repeatedly scanned over the course of several days. In contrast, we found that PPh3 rapidly decomposes under identical conditions. Density functional theory calculations performed on PPh3 and PPh4+ revealed large differences in the molecular orbital energies that were ascribed to differences in the phosphorus oxidation state (III versus V) and molecular charge (neutral versus +1). Time‐dependent density functional theory calculations corroborated the experimental data and allowed the spectral features to be assigned. The first pre‐edge feature in the P K‐edge XANES spectrum of PPh4Br was assigned to P 1s → P‐C π* transitions, whereas those at higher energy were P 1s → P‐C σ*. Overall, the analysis suggests that PPh4Br is an excellent alternative to other solid energy calibration standards commonly used in P K‐edge XANES experiments. 相似文献
915.
Tris‐amidoximate uranyl complexes via η2 binding mode coordinated in aqueous solution shown by X‐ray absorption spectroscopy and density functional theory methods 下载免费PDF全文
Linjuan Zhang Meiying Qie Jing Su Shuo Zhang Jing Zhou Jiong Li Yu Wang Shitong Yang Shuao Wang Jingye Li Guozhong Wu Jian-Qiang Wang 《Journal of synchrotron radiation》2018,25(2):514-522
The present study sheds some light on the long‐standing debate concerning the coordination properties between uranyl ions and the amidoxime ligand, which is a key ingredient for achieving efficient extraction of uranium. Using X‐ray absorption fine structure combined with theoretical simulation methods, the binding mode and bonding nature of a uranyl–amidoxime complex in aqueous solution were determined for the first time. The results show that in a highly concentrated amidoxime solution the preferred binding mode between UO22+ and the amidoxime ligand is η2 coordination with tris‐amidoximate species. In such a uranyl–amidoximate complex with η2 binding motif, strong covalent interaction and orbital hybridization between U 5f/6d and (N, O) 2p should be responsible for the excellent binding ability of the amidoximate ligand to uranyl. The study was performed directly in aqueous solution to avoid the possible binding mode differences caused by crystallization of a single‐crystal sample. This work also is an example of the simultaneous study of local structure and electronic structure in solution systems using combined diagnostic tools. 相似文献
916.
The spin-Hamiltonian parameters (g-factors g//, g⊥ and hyperfine structure constants A//, A⊥) of the square-planar CuS6 ?4 clusters in Cu(II)–bis [4-ethoxphenyl-O-alkyl]-dithiophosphonate complexes are computed with the high-order perturbation formulas based on the two-mechanism model. The model includes the contributions to spin-Hamiltonian parameters from the vastly-utilised crystal-field (CF) mechanism concerning the CF excited states and the generally-omitted charge-transfer (CT) mechanism due to CT excited states. The energy levels of CF and CT excited states needed in the calculation are obtained from the observed optical spectra. The calculated results are in rational accordance with the experimental values. The signs of constants A// and A⊥ are suggested and the reasons of the very small g-shifts |?gi| (= | gi ? ge |, where ge ≈ 2.0023 and i = // or ⊥) are discussed. 相似文献
917.
918.
Sadif A. Shirvan Fereydoon Khazali Sara Haydari Dezfuli Ali Borsalani 《Molecular Crystals and Liquid Crystals》2017,656(1):105-112
The new complex of [Hg(2-AMPy)2Cl]2.HgCl4 (1) was synthesized from the reaction of HgCl2 with 2-(aminomethyl)pyridine (2-AMPy) in methanolic solution. Suitable crystal of compound 1 for diffraction experiment was obtained by slow evaporation from dimethyl sulfoxide. Resulted complex was characterized by infrared, elemental analysis, thermal analysis, and single crystal X-ray diffraction. In the cationic part of this compound, two five-coordinated mercury centers have two different geometries, including distorted square-based pyramidal geometry by the trigonality index, τ5, of 0.23 and trigonal bipyramidal geometries by the trigonality index, τ5, of 0.57. 相似文献
919.
一些重金属离子即使在较低浓度时也会对环境、生物体产生毒性,所以研究痕量金属离子识别具有重大意义。荧光传感器由于具有选择性好、灵敏度高、成本低、实时响应等优点, 得到了广泛关注。以2,4-二叔丁基苯酚,3,5-二叔丁基水杨醛和邻氨基苯硫酚为原料合成了类Salen配体L1, 并用1H NMR,13C NMR,IR,元素分析及X射线单晶衍射等手段对其进行了表征。并通过自由挥发法得到了配体L1的单晶结构,实验表明L1是三斜晶、P-1空间群的一个空穴平面[ONSO]四配位环境。通过荧光光谱考察了类Salen配体与金属离子(Li+,Na+,K+,Cd2+,Cs+,Co2+,Cu2+,Hg2+,Mn2+,Ni2+,Zn2+,Ag+)的识别与配位性能。光谱滴定分析表明L1与Zn2+以1∶1的化学计量数配位。另外,L1与Zn2+结合后荧光显著增强,荧光检测限达到5.01×10-5 mol·L-1,而上述提到的其他常见金属离子不引起荧光光谱变化。结果表明L1是一个对检测Zn2+的选择性高,灵敏度强的荧光增强型探针。 相似文献
920.
设计并合成了四种联吡啶配体上共价修饰不同取代基的三羰基铼配合物fac-Re(L)(CO)3Cl: 即取代基分别为甲基(Re-Me)、羧基(Re-Ac)、季铵盐(Re-Qa)以及咪唑盐(Re-Im)的铼配合物, 化合物的结构均经过核磁氢谱、质谱以及红外光谱的确认, 测定了四种配合物第一和第二还原电位. 分别以该系列铼配合物为催化剂和光敏剂、三乙醇胺为电子牺牲体构建了均相可见光催化还原CO2体系, 配体上取代基对催化剂的催化效果有显著的影响, 催化活性Re-Qa> Re-Ac≈Re-Me> Re-Im. 不同实验条件下四种催化剂的吸收光谱随时间变化研究表明, 铼配合物的催化效果和其在催化过程中的失活速率密切相关, 其变化趋势与催化剂失活速率一致, 催化剂的失活发生在催化剂得到一个电子后的单电子还原态中间体(One-electron reduced species, OER). 瞬态吸收光谱检测到了催化过程中的OER的生成, 证实光催化还原CO2过程通过生成OER中间体进行的. 相似文献