全文获取类型
收费全文 | 101222篇 |
免费 | 17687篇 |
国内免费 | 9928篇 |
专业分类
化学 | 68623篇 |
晶体学 | 1132篇 |
力学 | 6810篇 |
综合类 | 533篇 |
数学 | 11864篇 |
物理学 | 39875篇 |
出版年
2024年 | 100篇 |
2023年 | 2065篇 |
2022年 | 2150篇 |
2021年 | 3231篇 |
2020年 | 4190篇 |
2019年 | 4050篇 |
2018年 | 3425篇 |
2017年 | 3159篇 |
2016年 | 5018篇 |
2015年 | 4714篇 |
2014年 | 5778篇 |
2013年 | 7537篇 |
2012年 | 9241篇 |
2011年 | 9763篇 |
2010年 | 6439篇 |
2009年 | 6157篇 |
2008年 | 6536篇 |
2007年 | 5998篇 |
2006年 | 5483篇 |
2005年 | 4597篇 |
2004年 | 3397篇 |
2003年 | 2622篇 |
2002年 | 2238篇 |
2001年 | 1900篇 |
2000年 | 1651篇 |
1999年 | 1974篇 |
1998年 | 1785篇 |
1997年 | 1659篇 |
1996年 | 1812篇 |
1995年 | 1491篇 |
1994年 | 1449篇 |
1993年 | 1156篇 |
1992年 | 1059篇 |
1991年 | 983篇 |
1990年 | 788篇 |
1989年 | 565篇 |
1988年 | 462篇 |
1987年 | 379篇 |
1986年 | 371篇 |
1985年 | 318篇 |
1984年 | 240篇 |
1983年 | 153篇 |
1982年 | 139篇 |
1981年 | 106篇 |
1980年 | 76篇 |
1979年 | 43篇 |
1978年 | 34篇 |
1976年 | 36篇 |
1975年 | 33篇 |
1974年 | 45篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Shujun Yu Xiangxue Wang Shitong Yang Guodong Sheng Ahmed Alsaedi Tasawar Hayat Xiangke Wang 《中国科学:化学(英文版)》2017,60(2):170-187
The X-ray absorption fine structure (XAFS) technology has exhibited a very unique application in the study of sorption mechanism, chemical species and microstructures of radionuclides at the natural solid-water interfaces. In this review, the interaction mechanism of radionuclides with clay minerals and nanomaterials under different environmental conditions are summarized from the XAFS spectroscopy analysis. The coordination number and the bond distances of radionuclides, the oxidation-reduction reactions, the influence of humic substances and microorganisms on the species and structures of radionuclides at molecule level are reviewed and compared. This review is helpful to understand the interactions of radionuclides with oxides, natural clay minerals and nanomaterials, which is also crucial to evaluate the physicochemical behaviors of radionuclides in the natural environment. 相似文献
992.
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
993.
Polymer electron acceptors are the key materials in all-polymer solar cells(all-PSCs).In this review,we focused on introducing the principle of boron-nitrogen coordination bond(B←N),and summarizing our recent research on polymer electron acceptors containing B←N unit for efficient all-PSC devices.Two approaches have been reported to design polymer electron acceptors using B←N unit.One is to replace a C-C unit by a B←N unit in conjugated polymers to transform a polymer electron donor to a polymer electron acceptor.The other approach is to construct novel electron-deficient building block based on B←N unit for polymer electron acceptors.The polymer electron acceptors containing B←N unit showed tunable lowest unoccupied molecular orbital(LUMO) energy levels and exhibited excellent all-PSC device performance with power conversion efficiency of exceeding6%.These results indicate that organic boron chemistry is a new toolbox to develop functional polymer materials for optoelectronic device applications. 相似文献
994.
Dunfeng Gao Fan Cai Guoxiong Wang Xinhe Bao 《Current Opinion in Green and Sustainable Chemistry》2017
Electrochemical reduction of CO2 provides a sustainable solution to address the intermittent renewable electricity storage while recycling CO2 to produce fuels and chemicals. Highly efficient catalytic materials and reaction systems are required to drive this process economically. This Review highlights the new trends in advancing the electrochemical reduction of CO2 by developing and designing nanostructured heterogeneous catalysts. The activity, selectivity and reaction mechanism are significantly affected by the nano effects in nanostructured heterogeneous catalysts. In the future, energy efficiency and current density in electrochemical reduction of CO2 need to be further improved to meet the requirements for practical applications. 相似文献
995.
996.
997.
Jingwei Wang Qianqian Luo Chunhua Luo Hechun Lin Ruijuan Qi Ni Zhong Hui Peng 《Journal of Solid State Electrochemistry》2017,21(7):2071-2077
In this study, MoS2 nanosheets were first prepared by exfoliating its bulk material in HCl/LiNO3 solution with a yield of 45%, and then a facile strategy was developed to synthesize polyaniline/MoS2 (PANI/MoS2) nanocomposite via in situ polymerization. Structural and morphological characterizations of MoS2 nanosheets and the nanocomposite were investigated by scanning electron microscope (SEM), transmission electron microscope (TEM), and X-ray powder diffraction. The results of SEM illustrated that orderly sawtooth polyaniline (PANI) nanoarrays were formed on the surface of MoS2 nanosheets. The nanocomposite displayed good electrochemical performance as a supercapacitor electrode material. The specific capacitance reached 560 F/g at a current density of 1.0 A g?1 in 1.0 M H2SO4 solution. Such good performance is because that the MoS2 nanosheets provided a highly electrolytic accessible surface area for redox-active PANI and a direct path for electrons. 相似文献
998.
Anirudra Parajuli Daniel H. Kwak Luca Dalponte Dr. Niina Leikoski Tomas Galica Ugochukwu Umeobika Dr. Laurent Trembleau Andrew Bent Prof. Kaarina Sivonen Matti Wahlsten Dr. Hao Wang Dr. Ermanno Rizzi Prof. Gianluca De Bellis Prof. James Naismith Prof. Marcel Jaspars Prof. Xinyu Liu Dr. Wael Houssen Dr. David Peter Fewer 《Angewandte Chemie (International ed. in English)》2017,56(2):433-433
999.
Dr. Hao Wang Dr. Jiji Zhang Prof. Dr. Zuowei Xie 《Angewandte Chemie (International ed. in English)》2017,56(31):9198-9201
A fully reversible photothermal isomerization between carborane-fused trigonal-planar azaborole (dark-purple) and tetrahedral borirane (pale-yellow) has been observed, leading to the isolation and structural characterization of the first example of carborane-fused borirane. DFT calculations indicate that the azaborole is thermodynamically more stable than the borirane by 11.2 kcal mol−1, and the energy barrier for the thermal conversion from azaborole to borirane is 35.5 kcal mol−1. The reactivity studies show that the B−C(cage) bond in borirane can be broken in the reaction with CuCl, HCl, or elemental sulfur. 相似文献
1000.
Xiao-Qiang Wang Fan Gao Prof. Dr. Xian-Zheng Zhang 《Angewandte Chemie (International ed. in English)》2017,56(31):9029-9033
Tumor hypoxia greatly suppresses the therapeutic efficacy of photodynamic therapy (PDT), mainly because the generation of toxic reactive oxygen species (ROS) in PDT is highly oxygen-dependent. In contrast to ROS, the generation of oxygen-irrelevant free radicals is oxygen-independent. A new therapeutic strategy based on the light-induced generation of free radicals for cancer therapy is reported. Initiator-loaded gold nanocages (AuNCs) as the free-radical generator were synthesized. Under near-infrared light (NIR) irradiation, the plasmonic heating effect of AuNCs can induce the decomposition of the initiator to generate alkyl radicals (R.), which can elevate oxidative-stress (OS) and cause DNA damages in cancer cells, and finally lead to apoptotic cell death under different oxygen tensions. As a proof of concept, this research opens up a new field to use various free radicals for cancer therapy. 相似文献