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141.
链酚胺型配体锌(Ⅱ)配合物模拟碳酸酐酶研究 总被引:1,自引:2,他引:1
合成了酚胺型链状配体,N,N'-二(2-羟基苄基)丙二胺(H~2L)及其Zn(Ⅱ)配合物(ZnL),通过元素分析、IR和^1HNRM等手段进行了表征。采用pH电位滴定法,在25℃±0.1℃,I=0.1mol·dm^-^3(KNO~3)条件下,测定了配体的质子化常数以及配体与金属离子Zn(Ⅱ)配位反应平衡常数。讨论了配体与金属离子Zn(Ⅱ)的配位情况,得到了配位酚羟基的解离常数。运用分光光度法,在25℃±0.1℃,I=0.1mol·dm^-^3(KNO~3)条件下,在pH=5.5~9.0(50mmol·dm^-^3缓冲溶液)范围内,研究了配合物作为碳酸酐酶模拟物催化对-硝基苯酚乙酸酯(NA)水解动力学,得到了NA酯水解的配合物催化速率常数k~N~P。实验结果表明,ZnHL^+的配位酚羟基的解离常数pK~a为6.83;催化速率常数k~N~P与pH之间不存在Sigmoidal型曲线关系,而是在pH值中性附近有最大值,ZnHL^+对NA酯水解有很好的催化效果,并且采取双重催化机理,是碳酸酐酶很好的模拟物。 相似文献
142.
The nucleophile [ArTe−] generated in situ borohydride solution of Ar2Te2, reacts with 2-(chloromethyl) tetrahydrofuran and 2-(2-bromoethyl)-1,3-dioxolane resulting in L1 and L2, respectively. The complexes of palladium(II) and platinum(II) with L1/L2 having stoichiometries [MCl2·L2], [ML2](ClO4)2, [(DPPE)ML2](ClO)4)2, [(PPh3)2ML2](ClO4)2 and [(phen)ML2](ClO4)2 (where L = L1/L2 DPPE = Ph2PC H2CH2PPh2, PHEN = 1,10-phenanthroline and M = Pd/Pt) have been synthesized. IR, 1H, 125Te{1H} and 31P{1H} NMR and UV-vis spectral data of these species in conjunction with their molar conductance and molecular weight data have been used to authenticate the new species. In all complexes (1–20) the ligands L1 and L2 are coordinated through tellurium and in the complexes of formula [ML2](ClO4)2 (M = Pd, Pt) the ligand is bidentate with the oxygen atom used in complexation. In solution, complexes PtCl2L2 exist as a mixture of cis and trans isomers whereas only the trans isomer was observed for the palladium analogues. The [(phen)PdL2](ClO4)2(Q) quenches 1O2 readily. The plot of log [Q] vs time is linear. Mechanism compatible with the experimental observations is proposed. 相似文献
143.
1,2-Diphenyl-1,2-dimethyldisilanylene-bridged bis-cyclopentadienyl complex[η~5,η~5-C_5H_4PhMeSiSiMePh-C_5H_4]Fe_2(CO)_2(μ-CO)_2(1)was synthesized by a modified procedure,from which the trans-isomer 1b that was pre-viously difficult to obtain has been isolated for the first time.More interestingly,two new regio-isomers[η~5,η~5C_5H_4SiMe(SiMePh_2)C_5H_4]Fe_2(CO)_2(μ-CO)_2(2)and [η~5,η~5-C_5H_4Me_2SiSiPh_2C_5H_4]Fe_2(CO)_2(μ-CO)_2(3)were occa-sionally obtained during above process,the novel structures of which opened up new options for further study ofthis type of Si—Si bond-containing transition metal complexes.The molecular structure of 2 has been determinedby the X-ray diffraction method. 相似文献
144.
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146.
葡聚糖为载体的双亲型LDL吸附剂吸附动力学研究 总被引:3,自引:0,他引:3
合成了以葡聚为载体,同时具有亲水性磺酸基和疏水性胆固醇两类配基的新型低密度脂蛋白(LDL)吸附剂。通过对LDL纯溶液中吸附等温线的测试,比较了以Dextran G-75为载体的双亲型LDL吸附剂与单一亲水型磺酸基配基,单一疏水型胆固醇基吸附剂吸附量和亲和吸附系数的关系。对双亲型LDL吸附剂的吸附动力学进行了初步研究,在LDL溶液中,亲水型磺酸基,疏水型胆固醇配基,双亲型LDL吸附剂对LDL的吸附曲线基本上符合Langmuir吸附方程,另外通过高离子强度NaCl洗脱实验,测定了双亲型LDL吸附剂上具有的磺酸基与胆固醇两类基在对低密脂蛋白吸附过程中所起的配合效果,为下一步作用力机制研究提供了参考依据。 相似文献
147.
Massimo Di Vaira Fabrizio Mani Piero Stoppioni 《Journal of organometallic chemistry》2004,689(10):1757-1762
The reaction of [CpRu(CH3CN)3]PF6 with the bidentate ligands L-L=1,2-bis(diphenylphosphino)ethane, dppe, and (1-diphenylarsino-2-diphenylphosphino)ethane, dpadppe, affords mononuclear or dinuclear complexes of formula [CpRu(η2-L-L)(CH3CN)]PF6, [{CpRu(CH3CN)2}2(μ-η1:1-L-L)](PF6)2 and [{CpRu(CH3CN)}2(μ-η1:1-L-L)2](PF6)2 (L-L=dppe, dpadppe). All of the compounds are characterized by microanalysis and NMR [1H and 31P{1H}] spectroscopy. The crystal structure of [{CpRu(CH3CN)2}2(μ-η1:1-dppe)](PF6)2 has been determined by X-ray diffraction analysis. The complex exhibits a dppe ligand bridging two CpRu(CH3CN)2 fragments. 相似文献
148.
Chun-Long?Chen Andrea?M.?Goforth Mark?D.?Smith William?R.?Gemmill Cheng-Yong?Su Hans-Conrad?zur?LoyeEmail author 《Journal of Cluster Science》2005,16(4):477-487
A new flexible ligand, 1,5-bis(8-oxaquinoline)-3-methylpentane (C5MeOQ), was synthesized and used in the preparation of the
new dinuclear copper(II) complex 1: [Cu2(μ-OMe)2(μ-C5MeOQ)(NO3)2]. Single crystal X-ray analysis revealed that complex 1 contains dinuclear Cu(II) units with bridging methoxo groups. The ligand, C5MeOQ, takes on a bent conformation in order to
connect to and complete the square planar coordination environment of both copper centers; and one of the two Cu(II) centers
adopts a distorted square planar configuration as a result of the ligand conformation. The magnetic properties of complex
1 were investigated by variable-temperature magnetic susceptibility measurements in the 100–300 K range. Interestingly, the
susceptibility data for complex 1 reveals that the compound is diamagnetic, suggesting the presence of very strong antiferromagnetic coupling interactions
between the adjacent Cu(II) centers. 相似文献
149.
An increasing number of docking/scoring programs are available that use different sampling and scoring algorithms. A reliable scoring function is the crucial element of such approaches. Comparative studies are needed to evaluate their current capabilities. DOCK4 with force field and PMF scoring as well as FlexX were used to evaluate the predictive power of these docking/scoring approaches to identify the correct binding mode of 61 MMP-3 inhibitors in a crystal structure of stromelysin and also to rank them according to their different binding affinities. It was found that DOCK4/PMF scoring performs significantly better than FlexX and DOCK4/FF in both ranking ligands and predicting their binding modes. Most notably, DOCK4/PMF was the only scoring/docking approach that found a significant correlation between binding affinity and predicted score of the docked inhibitors. However, comparing only those cases where the correct binding mode was identified (scoring highest among sampled poses), FlexX showed the best `fine tuning' (lowest rmsd) in predicted binding modes. The results suggest that not so much the sampling procedure but rather the scoring function is the crucial element of a docking program. 相似文献
150.
Herein we describe the importance of side chains in C3-symmetric ligands in supramolecular chemistry. The reaction of the new ligand tris(5-bromo-2-methoxybenzylidene)triaminoguanidinium chloride [H3Me3Br3L]Cl (1) with ZnCl2 results in the formation of the monomeric complex (Et3NH)2[(ZnCl2)3Me3Br3L] (2), in which the ligand remains in a conformation less favourable for the coordination of metal centres. The use of the related tris(5-bromo-2-hydroxybenzylidene)triaminoguanidinium chloride, [H6Br3L]Cl, under similar conditions, results in the formation of two different dimeric compounds (NH4)[{[Zn(NH3)]3Br3L}2{mu-(OH)}3]1/4MeOH (3) and [Zn{Zn2(OH2)3(NH3)Br3L}2] (4), depending on the solvent mixture used. The comparable reaction of the ligand tris(5-bromo-2-hydroxy-3-methoxybenzylidene)triaminoguanidinium chloride [H6(OMe)3Br3L]Cl (5), leads to the formation of a doughnut-shaped, protein-sized coordination oligomer (Et3NH)18[{Zn[Zn2Cl{(OMe)3Br3L}]2}6(mu-Cl)6(OH2)6]x CH3CN (6), which comprises six dimeric [Zn5{(OMe)3Br3L}2] units. Whereas 3 and 4 decompose in DMSO solution, 6 is surprisingly stable in the same solvent. 相似文献