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991.
Ramakrishna Dileep Badekai Ramachandra Bhat T.H. Suresha Kumara 《Green Chemistry Letters and Reviews》2014,7(1):32-36
Palladium (Pd)-catalyzed carbonylation of alcohols proceeds in ionic liquid (IL) media (1-ethyl-3-methylimidazolium hexafluorophosphate). Carbonylation of primary/secondary alcohols to aldehydes/ketones was greatly accelerated by the use of a Pd-based catalyst in the presence of NaOCl as an oxidant. The catalyst was more easier to recycle in the IL [Emim]PF6 with an equal-proportioned CH2Cl2 than in the single CH2Cl2 or IL. 相似文献
992.
Efficient Diketopyrrolopyrrole‐Based Small‐Molecule Bulk‐Heterojunction Solar Cells with Different Electron‐Donating End‐Groups 下载免费PDF全文
Yu Jin Kim Jang Yeol Back Seul‐Ong Kim Chan‐Woo Jeon Prof. Chan Eon Park Prof. Yun‐Hi Kim 《化学:亚洲杂志》2014,9(9):2505-2513
A series of small molecules that contained identical π‐spacers (ethyne), a central diketopyrrolopyrrole (DPP) unit, and different aromatic electron‐donating end‐groups were synthesized and used in organic solar cells (OSCs) to study the effect of electron‐donating groups on the device performance. The three compounds, DPP‐A‐Ph , DPP‐A‐Na , and DPP‐A‐An , possessed intense absorption bands that covered a wide range, from 350 to 750 nm, and relatively low HOMO energy levels, from ?5.50 to ?5.55 eV. DPP‐A‐An , which contained anthracene end‐groups, demonstrated a stronger absorbance and a higher hole mobility than DPP‐A‐Ph , which contained phenyl groups, and DPP‐A‐Na , which contained naphthalene units. The power‐conversion efficiencies (PCEs) of OSCs based on organic:PC71BM blends (1:1, w/w) with a processed DIO additive were 3.93 % for DPP‐A‐An , 3.02 % for DPP‐Na , and 2.26 % for DPP‐A‐Ph . These findings suggest that a DPP core that is functionalized with electron‐donating capping groups constitutes a promising new class of solution‐processable small molecules for OSC applications. 相似文献
993.
Semi-empirical AM1 and ZINDO/S, as well as density function theory (DFT) method B3LYP/6-31G(d) quantum chemical calculations were carried out to study the electronic structures and optical properties of poly(p-phenylene vinylene) derivatives (PPVs) with 10 and 11 phenylene rings in the backbone. The calculations suggest that the assembly of alternate incorporation of CN and alkoxy substituted phenylene rings in the PPV backbone could be a good way to construct organic semiconductors with low HOMO/LUMO energy band-gaps. The effect of the end-group on the electronic structures and optical properties of the conjugated polymer was investigated by the calculated UV-Vis and UPS spectra. It was demonstrated that the aldehyde and phosphate end-groups have limited effects on the photophysical properties in the UV-visible range. 相似文献
994.
杨理勤 《中国无机分析化学》2014,4(3)
回顾了中国金的分析技术的发展历程,重点论述了活性碳柱分离技术和泡沫塑料分离富集金技术的发明和革新对现代金的分析技术体系建立和发展的重要作用;阐述了纳微金分析技术革新和金的活动态分析、地电化学(泡塑)样品分析技术的新进展。 相似文献
995.
Kohei Matsuzaki Kenta Okuyama Etsuko Tokunaga Motoo Shiro Norio Shibata 《ChemistryOpen》2014,3(6):233-237
A sterically demanding unsymmetrical pentafluorophenyl-triisopropylphenyl-λ3-iodane was developed as an effective reagent for the electrophilic pentafluorophenylation of various β-keto esters and a β-keto amide. 17 examples of α-pentafluorophenylated 1,3-dicarbonyl compounds 3 having a quaternary carbon center are provided. The resulting compounds were nicely transformed into chiral α-pentafluorophenyl ketones with an all-carbon stereogenic center in high yields and high enantioselectivities using asymmetric organocatalysis (up to 98 % ee) or asymmetric metal catalysis (up to 82 % ee). 相似文献
996.
通过对气体净化,坩埚处理,试样处理及称样量选择,助熔剂种类及用量等因素的优化,建立了钢铁中超低含量碳硫的测定方法,实验结果表明:比较器水平设为1%,分析时间设为45s,坩埚在1 350℃下预烧45min,选择钨作为助熔剂且使用前在140℃烘3h,助熔剂用量为1.5g,称样量为0.5g时,是分析钢铁中碳硫含量在0.001%~0.01%的最佳条件,方法重复性好,准确度高,在实际操作中切实可行。 相似文献
997.
Tomá? Sára Thomas C Schwarz Dennis Kurzbach Christoph H Wunderlich Christoph Kreutz Robert Konrat 《ChemistryOpen》2014,3(3):115-123
Protein–protein interactions are of utmost importance to an understanding of biological phenomena since non-covalent and therefore reversible couplings between basic proteins leads to the formation of complex regulatory and adaptive molecular systems. Such systems are capable of maintaining their integrity and respond to external stimuli, processes intimately related to living organisms. These interactions, however, span a wide range of dissociation constants, from sub-nanomolar affinities in tight complexes to high-micromolar or even millimolar affinities in weak, transiently formed protein complexes. Herein, we demonstrate how novel NMR and EPR techniques can be used for the characterization of weak protein–protein (ligand) complexes. Applications to intrinsically disordered proteins and transiently formed protein complexes illustrate the potential of these novel techniques to study hitherto unobserved (and unobservable) higher-order structures of proteins. 相似文献
998.
Malte Behrends Charlotta Wallinder Anna Wieckowska Marie-Odile Guimond Anders Hallberg Nicole Gallo-Payet Mats Larhed 《ChemistryOpen》2014,3(2):65-75
A novel series of ligands for the recombinant human AT2 receptor has been synthesized utilizing a fast and efficient palladium-catalyzed procedure for aminocarbonylation as the key reaction. Molybdenum hexacarbonyl [Mo(CO)6] was employed as the carbon monoxide source, and controlled microwave heating was applied. The prepared N-aryl isoleucine derivatives, encompassing a variety of amide groups attached to the aromatic system, exhibit binding affinities at best with Ki values in the low micromolar range versus the recombinant human AT2 receptor. Some of the new nonpeptidic isoleucine derivatives may serve as starting points for further structural optimization. The presented data emphasize the importance of using human receptors in drug discovery programs. 相似文献
999.
《Journal of Saudi Chemical Society》2014,18(6):814-824
Schiff base metal complexes of Cr(III), Co(II), Ni(II) and Cu(II) derived from 5-chlorosalicylidene-2-amino-5-methylthiazole (HL1) and 2-hydroxy-1-naphthylidene-2-amino-5-methylthiazole (HL2) have been synthesized by conventional as well as microwave methods. These compounds have been characterized by elemental analysis, FT-IR, FAB-mass, molar conductance, electronic spectra, 1H-NMR, ESR, magnetic susceptibility, thermal, electrical conductivity and XRD analyses. The complexes exhibit coordination number 4 or 6. The complexes are coloured and stable in air. Analytical data reveal that all the complexes exhibit 1:2 (metal:ligand) ratio. IR data show that the ligand coordinates with the metal ions in a bidentate manner through the phenolic oxygen and azomethine nitrogen. FAB-mass and thermal data show degradation pattern of the complexes. The thermal behaviour of metal complexes shows that the hydrated complexes lose water molecules of hydration in the first step; followed by decomposition of ligand molecules in the subsequent steps. XRD patterns indicate crystalline nature for the complexes. The Schiff bases and metal complexes show good activity against the Gram-positive bacteria; Staphylococcus aureus and Gram-negative bacteria; Escherichia coli and fungi Aspergillus niger and Candida albicans. The antimicrobial results also indicate that the metal complexes are better antimicrobial agents as compared to the Schiff bases. 相似文献
1000.
Mapping of the Photoinduced Electron Traps in TiO2 by Picosecond X‐ray Absorption Spectroscopy 下载免费PDF全文
Dr. M. Hannelore Rittmann‐Frank Dr. Chris J. Milne Dr. Jochen Rittmann Dr. Marco Reinhard Dr. Thomas J. Penfold Prof. Majed Chergui 《Angewandte Chemie (International ed. in English)》2014,53(23):5858-5862
Titanium dioxide (TiO2) is the most popular material for applications in solar‐energy conversion and photocatalysis, both of which rely on the creation, transport, and trapping of charges (holes and electrons). The nature and lifetime of electron traps at room temperature have so far not been elucidated. Herein, we use picosecond X‐ray absorption spectroscopy at the Ti K‐edge and the Ru L3‐edge to address this issue for photoexcited bare and N719‐dye‐sensitized anatase and amorphous TiO2 nanoparticles. Our results show that 100 ps after photoexcitation, the electrons are trapped deep in the defect‐rich surface shell in the case of anatase TiO2, whereas they are inside the bulk in the case of amorphous TiO2. In the case of dye‐sensitized anatase or amorphous TiO2, the electrons are trapped at the outer surface. Only two traps were identified in all cases, with lifetimes in the range of nanoseconds to tens of nanoseconds. 相似文献