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991.
Four coordination polymers based on 4′-(2H-tetrazol-5-yl)biphenyl-4-carboxylic acid (H2TBPC), [Zn(μ3-TBPC)(H2O)]n (1), [Zn(μ3-TBPC)(Me2NH)]n (2), [Cd(μ3-TBPC)(bpy)]n (bpy = 4,4′-bipyridine, 3), and [Cd(μ4-TBPC)(H2O)]n (4), were constructed under hydrothermal conditions. The compounds are composed of M2(TBPC)2 binuclear ring as a building block. In 1–3, the binuclear rings are interconnected to three different 2-D networks with the same (4·82) topology. In 4, the binuclear rings are arranged into a 3-D framework with PtS-type topology. The results revealed that the structural diversity is mainly attributed to the coordination geometries of metal ion, the coordination modes of TBPC2?, and the auxiliary ligand. The thermal stabilities and luminescent properties of 1–4 have also been studied. 相似文献
992.
Three calcium coordination compounds, [Ca(CPA)(H2O)4]·(CPA), 1, [Ca(MCPA)2(H2O)2]·H2O, 2, and [Ca(TCPA)2(H2O)3]·2H2O, 3 [HCPA = 3-chlorophenoxyacetic acid, HMCPA = 2-methyl-4-chlorophenoxyacetic acid, and HTCPA = 2,4,6-trichlorophenoxyacetic acid], have been synthesized by the microwave method with advantages that include shorter reaction times, lower energy consumption, and higher product yield. The structures have been characterized by IR, elemental analysis, and single-crystal X-ray diffraction. Influences on the crystal structures by changing the number and position of chlorine substituent group in phenoxyacetic acid are discussed. Steric hindrance effects involving the Cl and an ability to form the O–H?Cl hydrogen bonds enrich the structure diversity. TG analysis reveals that the thermostability for the three compounds is 3 > 1 > 2, which could be influenced by the existence of hydrogen bonds (O–H?Cl and O–H?O). 相似文献
993.
Guang-Qi Jiang Ruo Wang Li-Li Long Tao Sun Zai-chang Yang Yun-Qian Zhang 《Journal of Coordination Chemistry》2016,69(4):678-686
Four new complexes have been prepared and characterized from reaction of the tetrapodal Schiff base ligand 1,1,1,1-tetrakis[(3-methoxysalicylaldimino)methyl]methane (H4L) with Cu(II), Ni(II) and Cd(II). X-ray diffraction experiments revealed that 1 ([Cu2L·2H2O]·H2O) and 2 ([Cu2L·2CH3OH]·3H2O) are dinuclear complexes, with the same tetragonal pyramidal coordination geometries around their Cu(II) ions. Complex 3 ([Ni2L]·2H2O) is dinuclear with two square planar Ni(II) ions coordinated to two pairs of the pendant branches of H4L. Complex 4 ([Cd3(HL)2]·3H2O) is a linear trinuclear species with three Cd(II) ions, which were intermolecularly coordinated to three pendant branches of two H4L ligands via an uncommon intermolecular phenoxo oxygen face-sharing mode. The in vitro antimicrobial activities of H4L and its complexes were evaluated against four micro-organisms (Colibacillus, Staphylococcus aureus, Pseudomonas aeruginosa, and Bacillus subtilis) using the tube-dilution method. The results revealed that 3 showed good inhibitory activity against the Gram-positive bacteria S. aureus and B. subtilis with MIC values of 62.5 and 31.0 μg mL, respectively. 相似文献
994.
Using a one-pot synthetic approach, a single isomer of bis(diethylenetriamine)cobalt(III) cation, [Co(dien)2]3+ is obtained in bulk from the isomeric mixture (s-fac : u-fac : mer is 7 : 28 : 65) using sodium salts of benzoates (BBz-bromobenzoate, DNBz-dinitrobenzoate, MBz-methylbenzoate) in aqueous medium. Herein, we report the syntheses and characterization of three complexes of composition mer-[Co(dien)2]Cl(p-BBz)2·H2O (1), s-fac-[Co(dien)2](o,p-DNBz)3·H2O (2) and mer-[Co(dien)2]Cl(p-MBz)2·4H2O (3) in the continuation of our earlier work, where benzoate (Bz), p-chlorobenzoate (CBz), p-nitrobenzoate (NBz) and p-aminobenzoate (ABz) were used. The isomeric identification of complex cation was initially made on the basis of spectroscopic characterization (UV–visible, IR and NMR). The binding properties of [Co(dien)2]3+ with benzoates (p-BBz, o,p-DNBz, p-MBz, Bz, CBz, NBz or ABz) have been studied using standard UV–visible spectroscopic titrations in aqueous medium and comparison indicate ion association constants of s-fac > mer. The single-crystal X-ray diffraction structure analysis of 3 reveals the presence of discrete ions ([Co(dien)2]3+, chloride, p-MBz) along with four lattice water molecules. The structure of 3, with formula [Co(dien)2](p-MBz)2Cl·4H2O, consists of alternating layers made of benzoate ions and layers made of [Co(dien)2]3+, chloride and water molecules. These layers result in the formation of their respective columns and intermolecular cohesion of p-MBz within the columns of [Co(dien)2]3+ is achieved via electrostatic and H-bonding interactions. 相似文献
995.
Yan-Peng Gao Le Guo Yan-Hua Lv Wei Dong Min Jia 《Journal of Coordination Chemistry》2016,69(24):3745-3761
We have synthesized a series of metal–organic coordination frameworks under solvothermal conditions, formulated as [Cu(L)(phen)](1), [Co2(L)2(bib)]·CH3OH(2), [Co(L)(btmb)0.5](3), [Zn(L)(bib)]·2H2O(4), [Cu(L)(bib)]·DMF(5), and [Mn4(L)4(bimb)(CH3OH)](6) based on a flexible multicarboxylic bridging ligand 4,4′-methylenebis(oxy)-dibenzoic acid (H2L) and flexible N-donor ligands 1,4-bis (1H-imidazol-1-yl)-butane (bib), 1,4-bis(1H-1,2,4-triazol- 1-ylmethyl)benzene (btmb), and 1,4-bis(1H-imidazol-1-ylmethyl)benzene (bimb). The structures of the frameworks have been determined by single-crystal X-ray diffraction analyses and further characterized by elemental analyses, IR spectra, and thermogravimetric analyses. The crystal structure determinations reveal that 1 has a 1-D Z-shape chain. Compounds 2 and 3 are 2-D twofold parallel interpenetrating 4-connected net with the Schläfli symbol {44·62}. Compound 4 is a 2-D threefold parallel interpenetrating 4-connected nets with the Schläfli symbol {44·62}. Compound 5 is 3-D 4-connected net with the Schläfli symbol {65·8}. Compound 6 is characterized by a three-dimensional framework with one-dimensional homogeneous Mn-carboxylate chain. We found that flexible carboxylate ligands have different coordination modes under different synthetic conditions. The flexible skeleton of ligands and the coordination angle between the ligand and the metal ion is described. The luminescence and thermogravimetric properties of these compounds have been investigated. 相似文献
996.
Protein environmental effects on iron‐sulfur clusters: A set of rules for constructing computational models for inner and outer coordination spheres 下载免费PDF全文
The structural properties and reactivity of iron‐sulfur proteins are greatly affected by interactions between the prosthetic groups and the surrounding amino acid residues. Thus, quantum chemical investigations of the structure and properties of protein‐bound iron‐sulfur clusters can be severely limited by truncation of computational models. The aim of this study was to identify, a priori, significant interactions that must be included in a quantum chemical model. Using the [2Fe‐2S] accessory cluster of the FeFe‐hydrogenase as a demonstrative example with rich electronic structural features, the electrostatic and covalent effects of the surrounding side chains, charged groups, and backbone moieties were systematically mapped through density functional theoretical calculations. Electron affinities, spin density differences, and delocalization indexes from the quantum theory of atoms in molecules were used to evaluate the importance of each interaction. Case studies for hydrogen bonding and charged side‐chain interactions were used to develop selection rules regarding the significance of a given protein environmental effect. A set of general rules is proposed for constructing quantum chemical models for iron‐sulfur active sites that capture all significant interactions from the protein environment. This methodology was applied to our previously used models in galactose oxidase and the 6Fe‐cluster of FeFe‐hydrogenase. © 2016 Wiley Periodicals, Inc. 相似文献
997.
Anticancer Potencies of PtII‐ and PdII‐linked M2L4 Coordination Capsules with Improved Selectivity 下载免费PDF全文
Dr. Anife Ahmedova Dr. Denitsa Momekova Masahiro Yamashina Dr. Pavletta Shestakova Prof. Dr. Georgi Momekov Prof. Dr. Munetaka Akita Dr. Michito Yoshizawa 《化学:亚洲杂志》2016,11(4):474-477
PtII‐ and PdII‐linked M2L4 coordination capsules, providing a confined cavity encircled by polyaromatic frameworks, exhibit anticancer activities superior to cisplatin against two types of leukemic cells (HL‐60 and SKW‐3) and pronounced toxicity against cisplatin‐resistant cells (HL‐60/CDDP). Notably, the cytotoxic selectivities of the PtII and PdII capsules toward cancerous cells are up to 5.3‐fold higher than that of cisplatin, as estimated through the non‐malignant/malignant‐cells toxicity ratio employing normal kidney cells (HEK‐293). In addition, the anticancer activity of the coordination capsules can be easily altered upon encapsulation of organic guest molecules. 相似文献
998.
用溶剂热法合成了2个以5-(4-(2,6-二(2-吡啶基)-4-吡啶基)苯氧基)间苯二甲酸(H_2L)为配体的金属-有机配位聚合物:{[NiL(H_2O)]·H_2O}_n(1),[Cd L(phen)]_n(2)。通过X-射线单晶衍射,元素分析和红外光谱进行了结构表征。结构分析表明,在1中,L~(2-)配体的2个羧基氧原子桥连相邻的2个Ni(Ⅱ)离子,形成平行于a轴的一维链,链间则通过吡啶氮原子与金属离子连接,最终形成具有(4,4)-连接三维网络结构。在2中,Cd(Ⅱ)为七配位的单帽三棱柱几何构型,L2-配体通过2个羧基和1个吡啶基与3个中心金属Cd(Ⅱ)相连,形成(3,3)-连接的二维层面结构,又通过面间的π…π堆积作用形成了3D超分子结构。测定了配位聚合物的热稳定性和2的荧光性质。 相似文献
999.
Simplest Monodentate Imidazole Stabilization of the oxy‐Tyrosinase Cu2O2 Core: Phenolate Hydroxylation through a CuIII Intermediate 下载免费PDF全文
Dr. Linus Chiang William Keown Dr. Cooper Citek Dr. Erik C. Wasinger Prof. T. Daniel P. Stack 《Angewandte Chemie (International ed. in English)》2016,55(35):10453-10457
Tyrosinases are ubiquitous binuclear copper enzymes that oxygenate to CuII2O2 cores bonded by three histidine Nτ‐imidazoles per Cu center. Synthetic monodentate imidazole‐bonded CuII2O2 species self‐assemble in a near quantitative manner at ?125 °C, but Nπ‐ligation has been required. Herein, we disclose the syntheses and reactivity of three Nτ‐imidazole bonded CuII2O2 species at solution temperatures of ?145 °C, which was achieved using a eutectic mixture of THF and 2‐MeTHF. The addition of anionic phenolates affords a CuIII2O2 species, where the bonded phenolates hydroxylate to catecholates in high yields. Similar CuIII2O2 intermediates are not observed using Nπ‐bonded CuII2O2 species, hinting that Nτ‐imidazole ligation, conserved in all characterized Ty, has functional advantage beyond active‐site flexibility. Substrate accessibility to the oxygenated Cu2O2 core and stabilization of a high oxidation state of the copper centers are suggested from these minimalistic models. 相似文献
1000.
Rotationally Active Ligands: Dialing‐Up the Co‐conformations of a [2]Rotaxane for Metal Ion Binding 下载免费PDF全文
Dr. Giorgio Baggi Prof. Dr. Stephen J. Loeb 《Angewandte Chemie (International ed. in English)》2016,55(40):12533-12537
A novel [2]rotaxane was constructed that has a bidentate N,N′‐chelate as part of a rigid, H‐shaped axle and a 24‐membered crown ether macrocycle containing six ether O‐atoms and an olefinic group as the wheel. This unique topology produces a ligand with the ability to dial‐up different donor sets for complexation to metal ions by simply rotating the wheel about the axle. The solution and solid‐state structures of the free ligand and complexes with Li+ and Cu+ show how the ligand adopts different rotational co‐conformations for each. The Li+ ion uses the N,N′‐chelate and O‐donors while the Cu+ center is coordinated to both O‐donors and the olefinic group. This concept of rotationally active ligands should be possible with a wide variety of donor sets and could find broad application in areas of coordination chemistry, such as catalysis and metal sequestration. 相似文献