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991.
Nonlinear Dynamics - The problem of propellant-efficient station-keeping using a hybrid sail in the Earth–Moon system is investigated in this paper. To achieve high-precision station-keeping... 相似文献
992.
993.
Xiaoqi Chen Jianping Xiao Jian Wang Dehui Deng Yongfeng Hu Jigang Zhou Liang Yu Thomas Heine Xiulian Pan Xinhe Bao 《Chemical science》2015,6(5):3262-3267
The electronic interaction of a catalyst and its support is of vital importance to its catalytic performance. However, it is still a great challenge to directly probe the interaction due to the lack of well-defined models and efficient technical means. In this study, we report that pod-like carbon nanotubes with encapsulated iron particles (Pod-Fe) and scanning transmission X-ray microscopy (STXM) can be used as an ideal model and technique to study the electronic interaction between carbon shells and iron particles. The chemical imaging and spectroscopy of Pod-Fe by STXM show that the local electronic structures at C K-edge near edge (π*) of carbon shells can be significantly modified by the encapsulated iron particles, which promotes the adsorption of oxygen-containing species, and thereby further modifies the electronic structure (π* and σ*) of the carbon shells. Moreover, computed X-ray absorption near edge structure spectra (XANES) confirmed the electronic modifications of carbon shells by the encapsulated iron particles. The present study provides a direct evidence of electronic interactions with simultaneously collected images and spectra, which can promote the understanding towards the nature of active sites and supports. 相似文献
994.
995.
Liang Yuanwei Huang Weiting Situ Qianyi Su Weiming Qiu Wenhua Li Shixiao He Luxin Chen Jianping 《Russian Journal of General Chemistry》2022,92(4):725-731
Russian Journal of General Chemistry - A series of 2,2′:6′,2′-terpyridine conjugated nitrogen mustard derivatives with structurally symmetrical character and rather small... 相似文献
996.
Hierarchically Self‐Assembled Star‐Shaped ZnO Microparticles for Electrochemical Sensing of Amines
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Prof. Dr. Jianping Du Xiaoxi Huang Dr. Ruihua Zhao Prof. Jinping Li Prof. Dr. Tewodros Asefa 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(24):8068-8073
Novel, hierarchically nanostructured, star‐shaped ZnO (SSZ) microparticles are synthesized by a hydrothermal synthetic route. The SSZ microparticles serve as effective platforms for electrochemical detection of amines in solution. The morphology and structure of the materials are characterized by X‐ray diffraction, scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, and UV/Vis spectroscopy. The as‐synthesized SSZ microparticles comprise self‐assembled hexagonal prisms that possess nanometer and micrometer pores in their structure and on their surfaces—structural features that are conducive to sensing applications. An electrode fabricated by using the hierarchically nanostructured SSZ materials serve as a sensitive electrochemical sensor for detection of low concentrations of ethylenediamine, with a sensitivity of 2.98×10?2 mA cm?2 mm ?1, a detection limit of 2.36×10?2 mm , and a short response time of 8 s. 相似文献
997.
Hailiang Chu Dr. Zhitao Xiong Prof. Dr. Guotao Wu Dr. Jianping Guo Xueli Zheng Teng He Chengzhang Wu Dr. Ping Chen Prof. Dr. 《化学:亚洲杂志》2010,5(7):1594-1599
Ca(BH4)2 is one of the promising candidates for hydrogen storage materials because of its high gravimetric and volumetric hydrogen capacity. However, its high dehydrogenation temperature and limited reversibility has been a hurdle for its practical applications. In an effort to overcome these barriers and to adjust the thermal stability, we make a composite system Ca(BH4)2–LiNH2. Interaction of Ca(BH4)2 and LiNH2 leads to decreased dehydrogenation temperatures and increased hydrogen desorption capacity in comparison to pristine Ca(BH4)2. More than 7 wt % of hydrogen can be detached at a temperature as low as approximately 178 °C from the cobalt‐catalyzed Ca(BH4)2–4 LiNH2 system. 相似文献
998.
对HIV-1整合酶(IN)野生体(WT),G140A/G149A和T66I/S153Y突变体分别进行了5 ns的分子动力学(MD)模拟,并用成簇和动力学交叉相关图(DCCM)分析了突变前后的构象变化.整体结构分析表明,突变后IN的活性口袋尺寸变化不大,T66I/S153Y突变体分子的整体运动性提高,而G140A/G149A突变体的功能loop区柔性明显上升.IN WT的方均根涨落(RMSF)模拟值与B因子实验值的较高相关性证明了柔性分析的合理性.通过成簇分析发现,IN在突变后功能loop区构象有开合运动,构象开放的概率是:体系G140A/G149A>T66I/S153Y>WT.最后DCCM分析结果表明,功能性分区的弱化以及DDE基序残基运动相关性的降低均有可能是突变体G140A/G149A和T66I/S153Y产生抗药性的原因.模拟结果对理解IN突变体的抗药机理以及为基于HIV-1 IN的药物分子设计提供了理论帮助. 相似文献
999.
Supriyo Bhattacharya Govindan Subramanian Spencer Hall Jianping Lin Abdelazize Laoui Nagarajan Vaidehi 《Journal of computer-aided molecular design》2010,24(8):659-674
The 41 amino acid neuropeptide, corticotropin-releasing factor (CRF) and its associated receptors CRF1-R and CRF2-R have been targeted for treating stress related disorders. Both CRF1-R and CRF2-R belong to the class B G-protein coupled receptors for which little information is known regarding the small molecule antagonist
binding characteristics. However, it has been shown recently that different non-peptide allosteric ligands stabilize different
receptor conformations for CRF1-R and hence an understanding of the ligand induced receptor conformational changes is important in the pharmacology of ligand
binding. In this study, we modeled the receptor and identified the binding sites of representative small molecule allosteric
antagonists for CRF1-R. The predicted binding sites of the investigated compounds are located within the transmembrane (TM) domain encompassing
TM helices 3, 5 and 6. The docked compounds show strong interactions with H228 on TM3 and M305 on TM5 that have also been
implicated in the binding by site directed mutation studies. H228 forms a hydrogen bond of varied strengths with all the antagonists
in this study and this is in agreement with the decreased binding affinity of several compounds with H228F mutation. Also
mutating M305 to Ile showed a sharp decrease in the calculated binding energy whereas the binding energy loss on M305 to Leu
was less significant. These results are in qualitative agreement with the decrease in binding affinities observed experimentally.
We further predicted the conformational changes in CRF1-R induced by the allosteric antagonist NBI-27914. Movement of TM helices 3 and 5 are dominant and generates three degenerate
conformational states two of which are separated by an energy barrier from the third, when bound to NBI-27914. Binding of
NBI-27914 was predicted to improve the interaction of the ligand with M305 and also enhanced the aromatic stacking between
the ligand and F232 on TM3. A virtual ligand screening of ~13,000 compounds seeded with ~350 CRF1-R specific active antagonists performed on the NBI-27914 stabilized conformation of CRF1-R yielded a 44% increase in enrichment compared to the initially modeled receptor conformation at a 10% cutoff. The NBI-27914
stabilized conformation also shows a high enrichment for high affinity antagonists compared to the weaker ones. Thus, the
conformational changes induced by NBI-27914 improved the ligand screening efficiency of the CRF1-R model and demonstrate a generalized application of the method in drug discovery. 相似文献
1000.
Treatment of 5,11,17,23‐tetrakis[(p‐carboxyphenyl)azo]‐25,26,27,28‐tetrahydroxy calix[4]arene ( 2 ) with HCl in DMF or NaOH in MeOH produced 5,11,17,23‐tetrakis[(p‐carboxyphenyl)azo]‐25,26,27,28‐tetrahydroxycalix[4]‐arene·4DMF (2·4DMF) and 5,11,17,23‐tetrakis[(p‐carboxyphenylsodium)azo]‐25,26,27,28‐tetrahydroxycalix[4]‐ arene ( 3 ), respectively, which were characterized by elemental analysis, IR, UV‐vis, 1H NMR and 13C NMR. An X‐ray analysis of 2·4DMF revealed that its calix[4]arene core adopts a flattened cone conformation in which opposed phenyl groups take parallel or sharply inclined positions. The intra‐ and intermolecular hydrogen‐bonding interactions and the π···π interactions form a 2D hydrogen‐bonded wavelike network. Compound 2 had a unique reversible color change in a wide pH range from 1 to 13.5 and showed interesting pH sensing properties. 相似文献