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991.
Wenbei Zhang Jiuli Chang Jianhua Chen Fang Xu Feng Wang Kai Jiang Zhiyong Gao 《Research on Chemical Intermediates》2012,38(9):2443-2455
A novel electrochemical sensor for para-nitrophenol (p-NP) was constructed with graphene–Au composite containing 10 % Au (G–Au 10 %). In the composite, Au nanoparticles with the size of ca. 11 nm were regularly scattered on graphene sheet without aggregation, which offers dramatically higher electrocatalytic activity on the redox of K3[Fe(CN)6]/K4[Fe(CN)6] couple than sole Au nanoparticles. Compared to sole Au nanoparticles, the G–Au 10 % also exhibited dramatically improved electrocatalytic activity on the reduction of p-NP. Amperometric detection of p-NP at G–Au 10 % modified electrode displayed a wide linear range of 0.47–10.75 mM with detection limit of 0.47 μM and a high sensitivity of 52.85 μA/mM. Considering the thrifty in utilization of noble Au, the G–Au 10 % can be successfully applied as a low-cost and powerful sensing material for trace detection of p-NP. 相似文献
992.
Poly(lactide-co-glycolide)-poly(ethylene glycol)-poly(lactide-co-glycolide)(PLGA-PEG-PLGA) triblock copolymer was synthesized through the ring-opening polymerization of LA and GA with PEG as macroinitiator and stannous octoate as catalyst. The amphiphilic copolymer self-assembled into micelles in aqueous solutions, and formed hydrogels as the increase of temperature at relatively high concentrations(〉 15 wt%). The favorable degradability of the hydrogel was confirmed by in vitro and in vivo degradation experiments. The good cellular and tissular compatibilities of the thermogel were demonstrated. The excellent adhesion and proliferation of bone marrow mesenchymal stem cells endowed PLGA-PEGPLGA thermogelling hydrogel with fascinating prospect for cartilage tissue engineering. 相似文献
993.
Shan Yang Zhiqing Zhang Fang Wang Lijuan Feng Xiaoxia Jiang Chuntian Yang Xianhong Jiang Guoqiang Liu 《Polymer Science Series A》2014,56(6):917-927
Several kinds of highly-branched block polyethers were synthesized via anion ring-opening polymerization of propylene oxide (PO) and ethylene oxide (EO), using phenol-amine resin (PA) as the initiator. The rheological properties determined by rotational rheometer all followed the regular rules of polymer systems: under a certain conditions, the bulk polyethers were pseudoplastic and non-Newtonian fluid, and with the increasing of the shear rate and temperature, the apparent viscosity of the block copolymers were reduced. In addition, modulus determination showed that such polyether molecules presented preferable viscosity compared to the elasticity, meanwhile, storage modulus, loss modulus and compound viscosity all decreased with the increasing of temperature. Storage modulus and loss modulus increased along with the scanning frequency increasing. But compared with the same kind of linear polymers, the significant difference was the low melt viscosity, which attributed to the special three-dimension space structure hindering the entanglement of chains. Furthermore, the rheological properties among the several block polyethers showed differences obviously. In other words, the number of block and the content of EO all have a significant effect on the rheological properties, specifically, the modulus will increase with the increasing of the block number and the EO content. 相似文献
994.
995.
Norman Lu Mani Alagesan Chi-Liang Ho Rong-Jyun Wei Chih-Chieh Kung Jung-Shan Chang Yuh-Sheng Wen Ling-Kang Liu 《Acta Crystallographica. Section C, Structural Chemistry》2016,72(12):1007-1011
It is possible that fluorous compounds could be utilized as directing forces in crystal engineering for applications in materials chemistry or catalysis. Although numerous fluorous compounds have been used for various applications, their structures in the solid state remains a lively matter for debate. The reaction of 4‐[(2,2,2‐trifluoroethoxy)methyl]pyridine with HX (X = I or Cl) yielded new fluorous ponytailed pyridinium halide salts, namely 4‐[(2,2,2‐trifluoroethoxy)methyl]pyridinium iodide, C8H9F3NO+·I−, (1), and 4‐[(2,2,2‐trifluoroethoxy)methyl]pyridinium chloride, C8H9F3NO+·Cl−, (2), which were characterized by IR spectroscopy, multinuclei (1H, 13C and 19F) NMR spectroscopy and single‐crystal X‐ray diffraction. Structure analysis showed that there are two types of hydrogen bonds, namely N—H…X and C—H…X. The iodide anion in salt (1) is hydrogen bonded to three 4‐[(2,2,2‐trifluoroethoxy)methyl]pyridinium cations in the crystal packing, while the chloride ion in salt (2) is involved in six hydrogen bonds to five 4‐[(2,2,2‐trifluoroethoxy)methyl]pyridinium cations, which is attributed to the smaller size and reduced polarizability of the chloride ion compared to the iodide ion. In the IR spectra, the pyridinium N—H stretching band for salt (1) exhibited a blue shift compared with that of salt (2). 相似文献
996.
采用乙醇挥发自组装法,以F127为模版,甲阶酚醛树脂为碳源,聚苯胺为配体,加入硝酸铁和硅酸盐,制备了有序多级孔的Fe-N-C-PANI催化剂.催化剂的成分和形貌表征结果表明,在热处理温度为800℃时,有序介孔的结构最清晰,拥有整齐的孔道和最高的比表面积(1007 m2/g);XPS分析结果表明,吡啶氮原子和石墨氮原子含量(摩尔分数)为3.86%.热处理温度升高过程中Fe(Ⅲ)被还原,向单质Fe转化,并促进了N的掺杂,使碳化铁转化为Fe-Nx活性位点,提高了催化剂的氧还原反应(ORR)催化活性,热处理温度达到900℃时,过多的单质铁使其氧还原活性下降.在酸性溶液中,Fe-N-C-PANI-800催化剂的起始电位可达0.89 V,半波电势为0.81 V.有序介孔结构使催化剂更易石墨化,提高了材料的稳定性. 相似文献
997.
Deep‐Level Defect Enhanced Photothermal Performance of Bismuth Sulfide–Gold Heterojunction Nanorods for Photothermal Therapy of Cancer Guided by Computed Tomography Imaging 下载免费PDF全文
Dr. Yan Cheng Yun Chang Yanlin Feng Hui Jian Prof. Zhaohui Tang Prof. Haiyuan Zhang 《Angewandte Chemie (International ed. in English)》2018,57(1):246-251
Bismuth sulfide (Bi2S3) nanomaterials are emerging as a promising theranostic platform for computed tomography imaging and photothermal therapy of cancer. Herein, the photothermal properties of Bi2S3 nanorods (NRs) were unveiled to intensely correlate to their intrinsic deep‐level defects (DLDs) that potentially could work as electron–hole nonradiative recombination centers to promote phonon production, ultimately leading to photothermal performance. Bi2S3‐Au heterojunction NRs were designed to hold more significant DLD properties, exhibiting more potent photothermal performance than Bi2S3 NRs. Under 808 nm laser irradiation, Bi2S3‐Au NRs could trigger higher cellular heat shock protein 70 expression and more apoptotic cells than Bi2S3 NRs, and caused severe cell death and tumor growth inhibition, showing great potential for photothermal therapy of cancer guided by computed tomography imaging. 相似文献
998.
A Pd(II)-catalyzed desulfitative arylation protocol between sulfonamides and sodium arylsulfinates was herein reported. The direct arylation reaction was successfully achieved by a Pd(II)/Ag(I)-mediated system without participation of any external ligands with a release of SO2. And different N-aryl sulfonamides were obtained readily in up to 86% yields, exhibiting good functional groups tolerance (25 examples). 相似文献
999.
A metal-free protocol for the selective cleavage of unstrained C–C single bonds was developed. Under the catalysis of KI and in the presence of NaHCO3, the readily available α-chloro-β-hydroxy ketones underwent bond breaking and sulfonylation smoothly to afford β-ketosulfones with high efficiency and broad substrate scope. Mechanism investigations, both experimental and theoretical, showed that a retro-aldol cleavage/nucleophilic substitution sequence might be involved. 相似文献
1000.
Metalloproteins have inspired chemists for many years to synthesize artificial catalysts that mimic native enzymes.As a complementary approach to studying native enzymes or making synthetic models,biosynthetic approach using small and stable proteins to model native enzymes has offered advantages of incorporating non-covalent secondary sphere interactions under physiological conditions.However,most biosynthetic models are restricted to natural amino acids.To overcome this limitation,incorporating unnatural amino acids into the biosynthetic models has shown promises.In this review,we summarize first synthetic,semisynthetic and biological methods of incorporates unnatural amino acids(UAAs)into proteins,followed by progress made in incorporating UAAs into both native metalloproteins and their biosynthetic models to fine-tune functional properties beyond native enzymes or their variants containing natural amino acids,such as reduction potentials of azurin,O_2 reduction rates and percentages of product formation of HCO models in Mb,the rate of radical transport in ribonucleotide reductase(RNR)and the proton and electron transfer pathways in photosystemⅡ(PSⅡ).We also discuss how this endeavour has allowed systematic investigations of precise roles of conserved residues in metalloproteins,such as Metl21 in azurin,Tyr244 that is cross-linked to one of the three His ligands to CuB in HCO,Tyr122,356,730 and 731 in RNR and TyrZ in PSⅡ.These examples have demonstrated that incorporating UAAs has provided a new dimension in our efforts to mimic native enzymes and in providing deeper insights into structural features responsible high enzymatic activity and reaction mechanisms,making it possible to design highly efficient artificial catalysts with similar or even higher activity than native enzymes. 相似文献