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941.
2,5‐Bis(2‐(diphenylphosphino)phenyl)‐1,3,4‐oxadiazole ligands and their Cu(I) complexes for Sonogashira coupling reaction 下载免费PDF全文
Cai‐Xia Lin Jia‐Fang Zhu Qing‐Shan Li Li‐Hua Ao Yan‐Juan Jin Feng‐Bo Xu Fang‐Zhong Hu Yao‐Feng Yuan 《应用有机金属化学》2014,28(4):298-303
Two diphosphane ligands – 2,5‐bis(2‐(diphenylphosphino)‐5‐R)phenyl)‐1,3,4‐oxadiazole ( L1 , R = H, L2 , R = OMe) and their binuclear complexes, L1Cu and L2Cu , were prepared and characterized. The molecular structures of L1Cu and L2Cu , as perchlorate salts, were established by X‐ray crystallography, which showed them to be binuclear complexes with each Cu atom tetrahedrally coordinated by two P atoms and two N atoms. The ligands and their Cu(I) complexes catalyzed Sonogashira coupling reactions of iodobenzene with phenylacetylene in the presence of K2CO3 under Pd‐free conditions. Coupling reactions catalyzed by L1 or L2 with Cu(MeCN)4ClO4 in situ exhibited better yields than those by the corresponding Cu(I) complexes L1Cu or L2Cu . Detailed studies showed L1 or L2 with Cu(MeCN)4ClO4 to be suitable catalysts for the coupling reaction of terminal alkynes and aryl halides. The coupling reactions of aryl iodides with electron‐withdrawing groups showed better results. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
942.
Yu‐En Tai Chen‐Yu Li Chia‐Her Lin Yi‐Chang Liu Bao‐Tsan Ko Ya‐Sen Sun 《Journal of polymer science. Part A, Polymer chemistry》2011,49(18):4027-4036
A series of efficient zinc catalysts supported by sterically bulky benzotriazole phenoxide ( BTP ) ligands are synthesized and structurally characterized. The reactions of diethyl zinc (ZnEt2) with CMe2PhBTP ‐H, t‐BuBTP ‐H, and TMClBTP ‐H yield monoadduct [(μ‐ BTP )ZnEt]2 ( 1 – 3 ), respectively. Bisadduct complex [( t‐BuBTP )2Zn] ( 4 ) results from treatment of ZnEt2 with t‐BuBTP ‐H (2 equiv.) in toluene, but treatment of TMClBTP ‐H with ZnEt2 in the same stoichiometric proportion in Et2O produces five‐coordinated monomeric complex [( TMClBTP )2Zn(Et2O)] ( 5 ). The molecular structures of compounds 1 , 4 , and 5 are characterized by X‐ray crystal structure determinations. All complexes 1 – 5 are efficient catalysts for the ring‐opening polymerization of ε‐caprolactone (ε‐CL) in the presence of 9‐anthracenemethanol. Experimental results indicate that complex 3 exhibits the greatest activity with well‐controlled character among these complexes. The polymerizations of ε‐CL and β‐butyrolactone catalyzed by 3 are demonstrated in a “living” character with narrow polydispersity indices (monomer‐to‐initiator ratio in the range of 25–200, PDIs ≤ 1.10). The “immortal” character of 3 provides a way to synthesize as much as 16‐fold polymer chains of poly(ε‐CL) (PCL) with narrow PDI in the presence of a catalyst in a small proportion. The controlled fashion of complex 3 also enabled preparation of the PCL‐b‐poly(3‐hydroxybutyrate) copolymer. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011 相似文献
943.
944.
Hui‐Ju Chuang Hsiao‐Li Chen Bor‐Hunn Huang Tsung‐En Tsai Pei‐Ling Huang Tzu‐Ting Liao Chu‐Chieh Lin 《Journal of polymer science. Part A, Polymer chemistry》2013,51(5):1185-1196
A series of zinc benzylalkoxide complexes, [LnZn(μ‐OBn)]2 (L = L 1 H – L 5 H ), supported by NNO‐tridentate ketiminate ligands with various electron withdrawing‐donating subsituents have been synthesized and characterized. X‐ray crystal structural studies revealed that complexes 2b and 4b are dinuclear bridging through the benzylalkoxy oxygen atoms with penta‐coordinated metal centers. All the metal complexes have acted as efficient initiators for the ring‐opening polymerization of L ‐lactide (within 12 min, 0 °C). Remarkably, a molecular weight of PLLA up to 580,000 can be achieved using [(L5Zn(μ‐OBn)]2 ( 5b ) as an initiator. The kinetic studies for the polymerization of L ‐lactide with complex 3b at ?10 °C corresponded to first‐order reactions in the monomer. The ring‐opening polymerization (ROP) of ε‐caprolactone, ε‐decalactone, β‐butyrolactone and their copolymer with complex 3b was investigated. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013 相似文献
945.
Torsten A. Enßlin 《Physik in unserer Zeit》2013,44(4):162-164
946.
Nian‐Yun Yang Xiao‐Hua Xu Dong‐Chun Ren Jin‐Ao Duan Ning Xie Li‐Juan Tian Shi‐Hui Qian 《Helvetica chimica acta》2010,93(1):65-71
Four new secoiridiod glucosides, p‐hydroxyphenethyl 7‐β‐D ‐glucosideelenolic acid ester ( 1 ), 6′‐elenolylnicotiflorine ( 2 ), 6′′′‐acetylnicotiflorine ( 3 ), and oleoside 7‐ethyl 11‐methyl ester ( 4 ), as well as six known glucosides, nuezhenide ( 5 ), Gl‐3 ( 6 ), nicotiflorine ( 7 ), isonuezhenide ( 8 ), neonuezhenide ( 9 ), and oleoside 11‐methyl ester ( 10 ) were isolated from the fruits of Ligustrum lucidum. Their structures were elucidated by spectroscopic methods. Compound 4 was an artifact produced during extraction. 相似文献
947.
Kinetic Model of Fixed Bed Reactor with Immobilized Microorganisms for Removing Low-Concentration SO2 下载免费PDF全文
Bing Huang YanyanWang Shiling Zhang Yong Ao 《天然气化学杂志》2007,16(1):86-91
On the basis of the analysis of the process of treating low concentrations of sulfur dioxide (SO2) gas in a fixed bed reactor, a kinetic model is proposed for this process after taking into consideration the effects of internal diffusion, cell concentration, and production yield of microorganisms but ignoring the effect of external diffusion. The results obtained from the model simulation show that this model can indicate the influence of the process factors, Cin,η,μmax, Cx,A, h, Km, and Q, on the removal of SO2 and that the prediction of the results by this model is also satisfactory. This kinetic model can also provide some very important indications regarding the preparation of immobilized microorganisms, selection and domestication of proper species of microorganisms, as well as the design of bioreactors. 相似文献
948.
Yuan Qiang Guo En Yong Ding Lian Zhen Gu Xue Hai Liang 《Journal of Macromolecular Science: Physics》2013,52(3):239-248
Thermodynamic properties and phase change behaviors of polyethylene glycol (PEG) in blends with cellulose (CELL) were found to be completely different than those of pure PEG. When the CELL fraction of the blend was larger than 5 wt%, PEG within the blend did not melt into a liquid state, as was the case with pure PEG, even at a temperature over 50°C above its melting point. Instead of fusion, a solid-solid phase transition was found in these PEG-CELL blends with an enthalpy as large as 100 J/g. 相似文献
949.
Three 3‐amino‐1, 2, 4‐triazole (atz)‐based paramagnetic complexes, [Mn(atz)(pa)]n ( 1 ), {[Mn(atz)1.5(hip)] · H2O}n ( 2 ), and [Mn(H2O)2(atz)2(nb)2] ( 3 ) (H2pa = o‐phthalic acid, H2hip = 5‐hydroxylisophthalic acid, and Hnb = p‐nitrobenzoic acid) were prepared by introducing different carboxylate‐containing aromatic coligands, and structurally and magnetically characterized. Helical MnII‐atz and bent MnII‐pa2– chains are crosslinked by sharing the same metal sites to generate a honeycomb‐shaped framework of 1 . The undulated MnII‐atz layers constructed from 22‐member metallomacrocycles are periodically supported by ditopic hip2– ligands to lead to a pillared‐layer structure of 2 . In contrast, complex 3 is a centrosymmetric mononuclear entity, which is assembled into a three‐dimensional supramolecular network by abundant hydrogen‐bonding interactions. The structural difference of 1 – 3 is significantly due to the combinations of the flexible coordination modes adopted by the mixed atz and carboxylate groups. Weak and comparable antiferromagnetic couplings are observed in the nearest neighbors of 1 – 3 , which are cooperatively transmitted either by short carboxylate and/or atz heterobridges or by weak non‐covalent interactions. 相似文献
950.
We show that a class of regular self-adjoint fourth order boundary value problems (BVPs) is equivalent to a certain class of matrix problems. Conversely, for any given matrix problem in this class, there exist fourth order self-adjoint BVPs which are equivalent to the given matrix problem. Equivalent here means that they have exactly the same spectrum. 相似文献