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971.
Changchang Xu Li Li Fangyuan Qiu Cuihua An Yanan Xu Ying Wang Yijing Wang Lifang Jiao Huatang Yuan 《天然气化学杂志》2014,(3):397-402
Assisted by graphene oxide(GO),nano-sized LiMn0.6Fe0.4PO4 with excellent electrochemical performance was prepared by a facile hydrothermal method as cathode material for lithium ion battery.SEM and TEM images indicate that the particle size of LiMn0.6Fe0.4PO4(S2)was about 80 nm in diameter.The discharge capacity of LiMn0.6Fe0.4PO4 nanoparticles was 140.3 mAh-g^1 in the first cycle.It showed that graphene oxide was able to restrict the growth of LiMn0.6Fe0.4PO4 and it in situ reduction of GO could improve the electrical conductivity of LiMn0.6Fe0.4PO4 material. 相似文献
972.
Hua Chyn Lee Kah Weng Siew Maksudur R.Khan Sim Yee Chin Jolius Gimbun Chin Kui Cheng 《天然气化学杂志》2014,(5):645-656
The paper reports the development of cement clinker-supported nickel (with metal loadings of 5 wt%, 10 wt%, 15 wt% and 20 wt%) catalysts for glycerol dry (CO2) reforming reaction. XRF results showed that CaO constituted 62.0% of cement clinker. The physicochemical characterization of the catalysts revealed 32-folds increment of BET surface area (SBET) with the addition of nickel metal into the cement clinker, which was also corroborated by FESEM images. Significantly, XRD results suggested different types of Ni oxides formation with Ni loading, whilst Ca3SiO5 and Ca2Al0.67Mn0.33FeO5 were the main crystallite species for pure cement clinker. Temperature-programmed reduction analysis yielded three domains of H2 reduction peaks, viz. centered at approximately 750 K referred to as type-Ⅰ peaks, another peaks at 820 K denoted as type-Ⅱ peaks and the highest reduction peaks, type-Ⅲ recorded at above 1000 K. 20 wt% Ni was found to be the best loading with the highest XG and H2 yield, whilst the lowest methanation activity. Syngas with lower H2/CO ratios (0.6 to 1.5) were readily produced from glycerol dry reforming at CO2-to-Glycerol feed ratio (CGR) of unity. Nonetheless, carbon deposit comprised of whisker type (Cv) and graphitic-like type (Cc) species were found to be in majority on 20 wt%Ni/CC catalysts. 相似文献
973.
利用L-谷氨酸苄酯开环聚合得到聚L-谷氨酸苄酯,对其进行表征,将聚L-谷氨酸苄酯溶于四氢呋喃后涂敷在3-氨丙基三乙氧基硅胶上制得液相色谱固定相,研究了正相色谱条件下聚L-谷氨酸苄酯涂敷型固定相对9种位置异构体及10种手性化合物的拆分能力。以不同比例的正己烷/异丙醇为流动相,有6种位置异构体(o,m,p-氯苯胺、o,m,p-溴苯胺、o,m,p-碘苯胺、o,m,p-硝基苯胺、o,m,p-二硝基苯和o,m,p-苯二胺)和4种手性化合物(1-(对氯苯基)乙醇、5-二硝基-N-(1-苯乙基)苯甲酰胺、华法林和四咪唑)得到不同程度的拆分,表明聚L-谷氨酸苄酯涂敷型固定相对位置异构体具有较好的识别作用,同时也表现出良好的手性拆分能力。 相似文献
974.
Dr. Lu Jin Fangyuan Cheng Hao Li Prof. Dr. Kui Xie 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(23):8976-8980
Porous tantalum nitride (Ta3N5) single crystals, combining structural coherence and porous microstructure, would substantially improve the photoelectrochemical performance. The structural coherence would reduce the recombination of charge carriers and maintain excellent transport properties while the porous microstructure would not only reduce photon scattering but also facilitate surface reactions. Here, we grow bulk-porous Ta3N5 single crystals on a two-centimeter scale with (002), (023), and (041) facets, respectively, and show significantly enhanced photoelectrochemical performance. We show the preferential facet growth of porous crystals in a lattice reconstruction strategy in relation to lattice match and lattice channel. We present the facet engineering to enhance light absorption, exciton lifetime and transport properties. The porous Ta3N5 single crystal boosts photoelectrochemical oxidation of alcohols with the (002) facet showing the highest performance of >99 % alcohol conversion and >99 % aldehyde/ketone selectivity. 相似文献
975.
Yuchao Zhu Ziyao Zhang Rui Jin Jianzhong Liu Guoquan Liu Prof. Bing Han Prof. Ning Jiao 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(45):20023-20028
Control of selectivity is one of the central topics in organic chemistry. Although unprecedented alkoxyl-radical-induced transformations have drawn a lot of attention, compared to selective C−H activation, selective radical O−H activation remains less explored. Herein, we report a novel selective radical O−H activation strategy of diols by combining spatial effects with proton-coupled electron transfer (PCET). It was found that DMSO is an essential reagent that enables the regioselective transformation of diols. Mechanistic studies indicated the existence of the alkoxyl radical and the selective interaction between DMSO and hydroxyl groups. Moreover, the distal C−C cleavage was realized by this selective alkoxyl-radical-initiation protocol. 相似文献
976.
Guifa Zhai Wenyan Wang Dr. Wei Xu Guo Sun Chaoqun Hu Xiangming Wu Zisong Cong Liang Deng Yanrong Shi Prof. Dr. Peter F. Leadlay Prof. Dr. Heng Song Prof. Dr. Kui Hong Prof. Dr. Zixin Deng Prof. Dr. Yuhui Sun 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(50):22926-22930
The colinearity of canonical modular polyketide synthases, which creates a direct link between multienzyme structure and the chemical structure of the biosynthetic end-product, has become a cornerstone of knowledge-based genome mining. Herein, we report genetic and enzymatic evidence for the remarkable role of an enoylreductase in the polyketide synthase for azalomycin F biosynthesis. This internal enoylreductase domain, previously identified as acting only in the second of two chain extension cycles on an initial iterative module, is shown to also catalyze enoylreduction in trans within the next module. The mechanism for this rare deviation from colinearity appears to involve direct cross-modular interaction of the reductase with the longer acyl chain, rather than back transfer of the substrate into the iterative module, suggesting an additional and surprising plasticity in natural PKS assembly-line catalysis. 相似文献
977.
草甘膦是目前世界上使用量最大的除草剂之一,被广泛应用于控制农田或非耕作用地中一年生或多年生杂草的生长[1]。草甘膦是一种生物蛋白质合成抑制剂,其通过抑制5-烯醇丙酮莽草酸-3-磷酸盐合成酶(EPSPs)的活性,使植物体内蛋白质合成受阻,致使植物死亡[2]。草甘膦原药在美国毒性分级中被评定为Ⅲ,被认为是相对较安全的农药,但经商品化改造的草甘膦的毒性是前者的数倍[3],会造成人体上皮细胞膜的损伤[4]、细胞中的血浆损伤和线粒体功能受损[5],甚至有致癌的风险。 相似文献
978.
Mengmeng Li Haijun Bin Xuechen Jiao Martijn M. Wienk He Yan Ren A. J. Janssen 《Angewandte Chemie (International ed. in English)》2020,59(2):846-852
It remains a challenge to precisely tailor the morphology of polymer monolayers to control charge transport. Herein, the effect of the dissolution temperature (Tdis) is investigated as a powerful strategy for morphology control. Low Tdis values cause extended polymer aggregation in solution and induce larger nanofibrils in a monolayer network with more pronounced π–π stacking. The field‐effect mobility of the corresponding monolayer transistors is significantly enhanced by a factor of four compared to devices obtained from high Tdis with a value approaching 1 cm2 V?1 s?1. Besides that, the solution kinetics reveal a higher growth rate of aggregates at low Tdis, and filtration experiments further confirm that the dependence of the fibril width in monolayers on Tdis is consistent with the aggregate size in solution. The generalizability of the Tdis effect on polymer aggregation is demonstrated using three other conjugated polymer systems. These results open new avenues for the precise control of polymer aggregation for high‐mobility monolayer transistors. 相似文献
979.
Yuxiang Chen Ke Gong Feng Jiao Xiulian Pan Guangjin Hou Rui Si Xinhe Bao 《Angewandte Chemie (International ed. in English)》2020,59(16):6529-6534
Despite significant progress achieved in Fischer–Tropsch synthesis (FTS) technology, control of product selectivity remains a challenge in syngas conversion. Herein, we demonstrate that Zn2+‐ion exchanged ZSM‐5 zeolite steers syngas conversion selectively to ethane with its selectivity reaching as high as 86 % among hydrocarbons (excluding CO2) at 20 % CO conversion. NMR spectroscopy, X‐ray absorption spectroscopy, and X‐ray fluorescence indicate that this is likely attributed to the highly dispersed Zn sites grafted on ZSM‐5. Quasi‐in‐situ solid‐state NMR, obtained by quenching the reaction in liquid N2, detects C2 species such as acetyl (‐COCH3) bonding with an oxygen, ethyl (‐CH2CH3) bonding with a Zn site, and epoxyethane molecules adsorbing on a Zn site and a Brønsted acid site of the catalyst, respectively. These species could provide insight into C?C bond formation during ethane formation. Interestingly, this selective reaction pathway toward ethane appears to be general because a series of other Zn2+‐ion exchanged aluminosilicate zeolites with different topologies (for example, SSZ‐13, MCM‐22, and ZSM‐12) all give ethane predominantly. By contrast, a physical mixture of ZnO‐ZSM‐5 favors formation of hydrocarbons beyond C3+. These results provide an important guide for tuning the product selectivity in syngas conversion. 相似文献
980.
Xingchen Jiao Kai Zheng Qingxia Chen Xiaodong Li Yamin Li Weiwei Shao Jiaqi Xu Junfa Zhu Yang Pan Yongfu Sun Yi Xie 《Angewandte Chemie (International ed. in English)》2020,59(36):15497-15501
Reported here is the first highly selective conversion of various waste plastics into C2 fuels under simulated natural environment conditions by a sequential photoinduced C?C cleavage and coupling pathway, where single‐use bags, disposable food containers, food wrap films, and their main components of polyethylene, polypropylene, and polyvinyl chloride can be photocatalytically transformed into CH3COOH without using sacrificial agents. As an example, polyethylene is photodegraded 100 % into CO2 within 40 h by single‐unit‐cell thick Nb2O5 layers, while the produced CO2 is further photoreduced to CH3COOH. Various methods and experiments disclose that O2 and .OH radicals trigger the oxidative C?C cleavage of polyethylene to form CO2, while other investigations show that the yielded CH3COOH stems from CO2 photoreduction by C?C coupling of .COOH intermediates. This two‐step plastic‐to‐fuel conversion may help to simultaneously address the white pollution crisis and harvest highly valuable multicarbon fuels in natural environments. 相似文献