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151.
152.
Junbo Li Wenlan Wu Chen Han Shijie Zhang Huiyun Zhou Jinwu Guo 《Colloid and polymer science》2014,292(7):1657-1664
Two distinctive block copolymers protected gold nanoparticles (AuNPs) were prepared with poly(methylacrylic acid)-block-poly(N-isopropylacrylamide) (SH-PMAA64-b-PNIPAM35) and poly (N-isopropylacrylamide)-block-poly(methylacrylic acid) (SH-PNIPAM40-b- PMAA60) through strong gold-sulfur bonding. The hybrid NPs have a pH-responsive inner shell (or corona) and a thermo-responsive corona (or inner shell) due to different location relations of the PNIPAM and PMAA on the surface of AuNPs. Then, the aggregation behaviors, as well as the changes of optical properties, of two hybrid NPs were compared in response to both stimuli. The results showed the obvious inter-particle aggregation caused by the phase transition for hydrophobic coronal polymer. However, the particles of hydrophilic corona layer retained good dispersion and the pH-responsive or thermo-responsive characteristics of shell layer made relatively minor changes. 相似文献
153.
Xiao Jiang Peipei Li Xiumei Liu Xinwen Guo Li Liu 《Journal of inclusion phenomena and macrocyclic chemistry》2014,80(3-4):457-461
A novel microwave-assisted route to synthesize cucurbit[n]uril in SO3H-functionalized ionic liquids was reported, which enabled the automatic separation of cucurbit[6]uril through anion assembly. For the first time, the route has realized synthesis–assembly–separation of cucurbit[6]uril in one pot. The reaction yield and separation efficiency can be tuned by choice of anionic groups in ionic liquids. 相似文献
154.
Fenglan Fan Chengguang Gao Lihua Jia Xiangfeng Guo 《Research on Chemical Intermediates》2014,40(1):157-167
A novel ZnO/Ca(OH)2/KF solid base catalyst was prepared by the grinding method and applied to biodiesel synthesis by the transesterification of soybean oil. The effect of various parameters such as KF molar amount, calcination temperature, the amount of catalyst, molar ratio of methanol to oil, reaction temperature, and time on the activity of the catalyst were investigated. The catalysts were characterized by several techniques of thermogravimetry/derivative thermogravimetry, X–ray diffraction, Hammett indicator method, and scanning electron microscopy. The analysis results indicated that the KF interacted with Ca(OH)2 and formed KCaF3 phase before calcination of the catalyst. The formed KCaF3 crystal phase was the main catalytic active component for the catalyst activity. In addition, the basicity of ZnO/Ca(OH)2/KF was greatly influenced by the different calcination temperates, and the catalyst activity was correlated closely with the basicity. A desired biodiesel yield of 97.6 % was obtained at catalyst amount of 3 %, methanol/oil of 12:1, and reaction time of 1.5 h at 65 °C. 相似文献
155.
Liangzhao Cai Mengyao Xue Jia Lun Shuang Li Jia Yu Xingjie Guo 《Electrophoresis》2020,41(24):2092-2101
The enantioseparation of eight psychoactive drugs has been firstly performed on a coated cellulose-based chiral stationary phase (Chiralcel OJ-H). To obtain optimum separation conditions, the influences of alcohol modifiers and basic/acidic additives have been studied. As a result, except for the partial separation of oxybutynin enantiomers, the other seven drug enantiomers, including mirtazapine, sulpiride, promethazine, citalopram, oxazepam, donepezil, and cyamemazine, have been completely separated. Additionally, for gaining a better insight into the chiral recognition mechanisms, molecular docking was carried out using the Autodock software. Herein, binding energy and conformations of the chiral stationary phase complexes were provided, and it was found that the distinction in enantiomeric conformation determined the number and strength of intermolecular interactions between analytes and chiral stationary phase which resulted in the difference in binding energies of two enantiomers, and ultimately led to the different migration. These modeling results were in accordance with the observed enantioseparation results in high performance liquid chromatography experiments. At last, chiral separation mechanisms have been discussed in detail, and it has been confirmed that hydrogen bond, π–π, hydrophobic interactions, and some special interactions synergistically contributed to the enantioseparation of psychoactive drugs. 相似文献
156.
Dandan Jiang Mingxing Fu Yajun Zhang Qianqian Li Kai Guo Yanhui Yang Lili Zhao 《Journal of computational chemistry》2020,41(4):279-289
Density functional theory (DFT) calculations were performed to gain insight into the mechanism of the nickel-catalyzed hydrocyanation of terminal alkynes with Zn(CN)2 and water to exclusively generate the branched nitrile with excellent Markovnikov selectivity. After precatalyst activation to give the LNi(0) active species, the transformation proceeds via the following steps: (1) oxidative addition of H2O to the LNi(0) provides the intermediate LNi(II)H(OH); (2) ligand exchange of LNi(II)H(OH) with Zn(CN)2 gives the intermediate LNi(II)H(CN); (3) alkyne insertion to the LNi(II)H(CN) forms the alkenyl nickel complex, followed by the reductive elimination step reaching the final product. This mechanism is kinetically and thermodynamically more favorable than that of the experimental proposed ones. On the basis of the experimental observations, more water molecules cannot further improve the reaction as it has also been rationalized. Furthermore, the origin of the high regioselectivity of the product, the variable effectiveness of the metal mediator as function of ligands, as well as the high yield of the alkyl-substituted alkynes substrates, is analyzed in detail. © 2019 Wiley Periodicals, Inc. 相似文献
157.
Guozhu Li Qinzhe Liu Laxmaiah Vasamsetty Weicong Guo Prof. Dr. Jun Wang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(9):3503-3507
A ruthenium(II)-catalyzed asymmetric intramolecular hydroarylation assisted by a chiral transient directing group has been developed. A series of 2,3-dihydrobenzofurans bearing chiral all-carbon quaternary stereocenters have been prepared in remarkably high yields (up to 98 %) and enantioselectivities (up to >99 % ee). By this methodology, a novel asymmetric total synthesis of CB2 receptor agonist MDA7 has been successfully developed. 相似文献
158.
Shaojun Guo 《物理化学学报》2020,36(7):2001012-0
正发展电解水制氢和金属-空气电池等电化学能源转化与存储技术对于解决日益严峻的能源短缺和环境污染问题具有重要意义~1。氧气析出反应(OER)是电解水制氢和金属-空气电池的关键半反应,但其缓慢的动力学过程却限制了上述能源技术的快速发展~(2,3)。钌/铱基催化剂是当前最为有效 相似文献
159.
Tzu‐Yu Chen Jinfeng Chen Yijie Tang Jiahai Zhou Yisong Guo Wei‐chen Chang 《Angewandte Chemie (International ed. in English)》2020,59(19):7367-7371
N‐alkylisonitrile, a precursor to isonitrile‐containing lipopeptides, is biosynthesized by decarboxylation‐assisted ‐N≡C group (isonitrile) formation by using N‐alkylglycine as the substrate. This reaction is catalyzed by iron(II) and 2‐oxoglutarate (Fe/2OG) dependent enzymes. Distinct from typical oxygenation or halogenation reactions catalyzed by this class of enzymes, installation of the isonitrile group represents a novel reaction type for Fe/2OG enzymes that involves a four‐electron oxidative process. Reported here is a plausible mechanism of three Fe/2OG enzymes, Sav607, ScoE and SfaA, which catalyze isonitrile formation. The X‐ray structures of iron‐loaded ScoE in complex with its substrate and the intermediate, along with biochemical and biophysical data reveal that ‐N≡C bond formation involves two cycles of Fe/2OG enzyme catalysis. The reaction starts with an FeIV‐oxo‐catalyzed hydroxylation. It is likely followed by decarboxylation‐assisted desaturation to complete isonitrile installation. 相似文献
160.
Dr. Mingliang Li Dr. Xiaoge Wang Guozhi Wang Shizhao Ren Shuo Li Prof. Feng Wei Prof. Shouke Yan Prof. Xuefeng Guo Prof. Hailing Tu 《Chemphyschem》2020,21(2):181-186
Organic semiconductor (OSC) crystals have great potential to be applied in many fields, as they can be flexibly designed according to the demands and show an outstanding device performance. However, OSCs with the capacity of solid-state crystallization (SSC) are developing too slowly to meet demands in productions and applications, due to their difficulties in molecular design and synthesis, unclear mechanism and high dependence on experimental conditions. In this work, in order to solve the problems, we synthesized an organic semiconductor capable of SSC at room temperature by adjusting the relationship between conjugated groups and functional groups. The thermodynamic and kinetic properties have been studied to discover the model of film SSC. Moreover, it can be purposefully controlled to prepare the high-quality crystals, and their corresponding organic electronic devices were further fabricated and discussed. 相似文献