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871.
Photolysis studies on HCOOH and HCOO− in presence of TiO2 photocatalyst as suspension in aqueous medium 下载免费PDF全文
Photolysis studies on formic acid (HCOOH) and formate ion (HCOO−) in presence of TiO2, a photocatalyst, as suspension in water
were carried out separately using 350 nm ultraviolet light. The products, such as H2, CO, CO2 and CH4, generated during the experiments were monitored with varying the ambient, light exposure time, and the concentration of HCOOH/HCOO−. The yields of CO in all these systems increased with light exposure time. In aerated systems, CO yields were higher in contrast to the deoxygenated (Ar-purged) systems under identical conditions. It is proposed apparently that the formation of CO is taking place during the chemical reduction of in-situ generated CO2, a photo-mineralized product of HCOOH/HCOO−, but not through the direct photodecomposition or photodehydration (CO+H2O) of solute molecules. The rates of CO formation during 1.3 M HCOOH photolysis in presence of TiO2 photocatalyst were evaluated to be 0.21 and 0.13 μl/min in aerated and Ar-purged systems, respectively. As compared with HCOOH systems, the CO yields are lower when 0.2 M HCOONa was exposed to light under identical conditions. The CO growth rates were evaluated to be 0.07 and 0.046 μl·min−1 for aerated and deoxygenated HCOONa systems, respectively; moreover, the trend is quite similar to that of the HCOOH system. Under these conditions, the emission of H2 was also observed, and its yield was significantly higher in Ar-purged system as compared with the CO yields. However, in aerated system, the yields of these products were just opposite. The formation of low yield of methane was observed during photolysis of HCOOH/HCOO− ions. In CO2 ambient, the yields of CO and H2 varied drastically with time. 相似文献
872.
Dilip Kumar Dey Sankar Prasad Dey Amitabha Datta Georgina M. Rosair 《Journal of organometallic chemistry》2009,694(15):2434-440
Two diorganotin(IV) complexes of the general formula R2Sn[Ph(O)CCH-C(Me)N-C6H4(O)] (R = Ph, 1a; R = Me, 1b) have been synthesized from the corresponding diorganotin(IV) dichlorides and the ligand, 3-(2-hydroxyphenylimino)-1-phenylbutan-1-one (1) in methanol at room temperature in presence of triethylamine. Both compounds have been characterized by elemental analyses, IR and 1H, 13C, 15N, 119Sn NMR spectra. The structures of the free ligand and the complexes have been confirmed by single crystal X-ray diffraction. There are three independent molecules in the crystal structure of the ligand 1 and in all three the O-bound proton is transferred to the imine nitrogen and makes an intramolecular N-H?O hydrogen bond with the carbonyl oxygen. In turn this makes an intermolecular hydrogen bond with the phenolic H atom. The crystal structure of 1 is trigonal and a new polymorph; triclinic and monoclinic forms have already been published. In 1a, the central tin atom adopts distorted trigonal-bipyramidal coordination geometry whereas in dimeric 1b it is distorted octahedral when including the intermolecular Sn-O(phenolic) bond [2.7998(20) Å]. The δ (119Sn) values for the complexes 1a and 1b are −306.6 and −127.9 ppm, respectively, thus indicating penta-coordinated Sn centres in solution. 相似文献
873.
Kishore Kumar Pasikanti Juwita Norasmara Shirong Cai Ratha Mahendran Kesavan Esuvaranathan Paul C. Ho Eric Chun Yong Chan 《Analytical and bioanalytical chemistry》2010,398(3):1285-1293
In this study, gas chromatography mass spectrometry (GC-MS) and two-dimensional gas chromatography time-of-flight mass spectrometry
(GC×GC-TOFMS) were employed for the metabolic footprinting of a pair of immortalized human uroepithelial cells namely HUC-1
(nontumorigenic) and HUC T-2 (tumorigenic). Both HUC-1 and HUC T-2 cell lines were cultivated in 1 mL of Ham’s F-12 media.
Subsequent to 48 h of incubation, 200 μL of cell culture supernatant was protein-precipitated using 1.7 mL of methanol and
an aliquot of 1.5 mL of the mixture was separated, dried, trimethylsilyl-derivatized, and analyzed using GC-MS and GC×GC-TOFMS.
Metabolic profiles were analyzed using multivariate data analysis techniques to evaluate the changes of the metabolomes. Both
GC-MS and GC×GC-TOFMS analyses showed distinct differences in metabolic phenotypes of the normal and tumorigenic human bladder
cells (partial least squares-discriminant analysis (PLS-DA) of GC×GC-TOFMS data; two latent variables, R
2
X = 0.418, R
2
Y = 0.977 and Q
2 (cumulative) = 0.852). Twenty metabolites were identified as being statistically different between the two cell types. These
metabolites revealed that several key metabolic pathways were perturbed in tumorigenic urothelial cells as compared to the
normal cells. Application of GC×GC-TOFMS offered several advantages compared to classical one-dimensional GC-MS which include
enhanced chromatographic resolution (without increase in analytical run time), increase in sensitivity, improved identification
of metabolites, and also separation of reagent artifacts from the metabolite peaks. Our results reinforced the advantages
of GC×GC-TOFMS and the role of metabolomics in characterizing bladder cancer biology using in vitro cell culture models. 相似文献
874.
Rajkumar Misra Sanjit Dey Rahi M. Reja Prof. Dr. Hosahudya N. Gopi 《Angewandte Chemie (International ed. in English)》2018,57(4):1057-1061
Double helices are not common in polypeptides and proteins except in the peptide antibiotic gramicidin A and analogous l,d ‐peptides. In contrast to natural polypeptides, remarkable β‐double‐helical structures from achiral γ‐peptides built from α,β‐unsaturated γ‐amino acids have been observed. The crystal structures suggest that they adopted parallel β‐double helical structures and these structures are stabilized by the interstrand backbone amide H‐bonds. Furthermore, both NMR spectroscopy and fluorescence studies support the existence of double‐helical conformations in solution. Although a variety of folded architectures featuring distinct H‐bonds have been discovered from the β‐ and γ‐peptide foldamers, this is the first report to show that achiral γ‐peptides can spontaneously intertwine into β‐double helical structures. 相似文献
875.
A reversible ‘turn-on’ sensor has been designed for ‘naked-eye’ detection of oxalate at nanomolar concentration (~12.5?nM) at pH 7.4. The sensory system shows a highly specific response towards oxalate among a wide range of antinutrients and biologically relevant anionic species. Mechanistic investigations indicate that oxalate can turn the pink-colored solution colorless by dissociating the preformed metal complex. Additionally, high specificity and good accuracy with recovery values ranging from 93.3 to 105.0% were obtained during oxalate estimation in spiked water and human urine samples, confirming the suitability of the present method in estimating trace-level of oxalate in complex matrices. With these results, quantitative estimations of endogenous oxalate were achieved in more than twenty-five different agricultural crops. Finally, low-cost, portable paper strips were developed for on-site detection of oxalate. 相似文献
876.
Richa Vinayak Dhritiman Dey Dipanjan Ghosh Dhrubajyoti Chattopadhyay Abhrajyoti Ghosh Hari Pada Nayek 《应用有机金属化学》2018,32(3)
Three mononuclear organotin(IV) complexes supported by Schiff bases have been synthesized. The complexes [(C6H5)2Sn(L)] ( 1 ), [(t‐Bu)2Sn(L)] ( 2 ) and [(t‐Bu)2Sn(L')] ( 3 ) (L, L' = deprotonated Schiff bases) were obtained in good yield by the reaction of Schiff bases H 2 L or H 2 L′ with corresponding diorganotin dichlorides respectively. All newly synthesized complexes were characterized by means of FT‐IR spectroscopy, elemental analysis and multinuclear (1H, 13C and 119Sn) NMR spectroscopy. In addition, single crystal X‐ray diffraction analyses were employed to establish the solid state molecular structures of these complexes. The structures of 1 – 3 reveal that all complexes are mononuclear with a five‐coordinated tin(IV) centre in it. The absorption and emission properties of all complexes have been investigated. Moreover, cytotoxicity and fluorescence cell imaging studies of theses complexes have been performed. 相似文献
877.
One-electron oxidation of thionine has been studied using specific oxidizing radicals such as Cl−Tl(II) and N3 generated by pulse radiolysis of aqueous solutions. The semioxidized thionine exhibited threepK’s indicating four conjugate acid-base forms. N3 radicals were found to be less efficient in oxidizing thionine as compared to Cl
2
−
, Tl2+ and Tl(OH)+. The rate constants for electron abstraction from thionine by Cl
2
−
, Tl2+, Tl(OH)+, Tl(OH)2 and N3 were evaluated. The spectra of different protonated forms of semioxidized thionine and the extinction coefficients at λmax are presented. Reaction of OH radicals with thionine gave transient products whose spectra and acid-base properties were
different from those of semioxidized thionine. The rate constant for formation of the product transient agrees well with competition
kinetic value for reaction of OH with thionine reported earlier. 相似文献
878.
Dr. Marion Poncet Dr. Ang Li Geoffrey Gontard Lise-Marie Chamoreau Dr. Yanling Li Dr. Laurent Lisnard Dr. Jurgen Von Bardeleben Dr. Sourav Dey Prof. Gopalan Rajaraman Dr. Yves Journaux 《欧洲无机化学杂志》2023,26(22):e202300242
The reaction of multi-bidentate oxamate-based copper(II) complexes with the [Ni(iPrtacn)Cl2] complex (iPrtacn:1,4,7-triisopropyl-1,4,7-triazacyclononane) has been investigated. X-ray diffraction studies reveal that for all compounds the oxamato κO,κΟ’ bidentate coordination site replaces the two chloride ions in [Ni(iPrtacn)Cl2] to form trimetallic {CuNi2} ( 1 – 3) , hexametallic {Cu2Ni4} ( 4 ) and enneametallic {Cu3Ni6} ( 5 ) complexes. The investigation of the magnetic properties shows that Cu−Ni interactions through the oxamato bridge are in the expected range (−111 cm−1, −68 cm−1). For 1 – 3 , both the sign and strength of the magnetic couplings are computed independently from DFT calculations, and these estimates broadly agree with the experiments. The magnetization measurements and EPR studies reveal that 1 – 3 are anisotropic: a significant portion of the large anisotropy of the [Ni(iPrtacn)Cl2] complex is retained, resulting in a D value for the S=3/2 ground state of 5 cm−1 on average. This is no longer the case for 4 and 5 where the anisotropy of the Ni(II) complexes is diluted due to the high nuclearity of the final edifices. These results show that it is possible to obtain trimetallic complexes with a high anisotropy and a high spin value for the ground state by a judicious choice of the interacting metal ions. 相似文献
879.
Katharigatta N. Venugopala Sandeep Chandrashekharappa Christophe Tratrat Pran Kishore Deb Rahul D. Nagdeve Susanta K. Nayak Mohamed A. Morsy Pobitra Borah Fawzi M. Mahomoodally Raghu Prasad Mailavaram Mahesh Attimarad Bandar E. Aldhubiab Nagaraja Sreeharsha Anroop B. Nair Osama I. Alwassil Michelyne Haroun Viresh Mohanlall Pottathil Shinu Rashmi Venugopala Mahmoud Kandeel Belakatte P. Nandeshwarappa Yasmine F. Ibrahim 《Molecules (Basel, Switzerland)》2021,26(12)
The cyclooxygenase-2 (COX-2) enzyme is an important target for drug discovery and development of novel anti-inflammatory agents. Selective COX-2 inhibitors have the advantage of reduced side-effects, which result from COX-1 inhibition that is usually observed with nonselective COX inhibitors. In this study, the design and synthesis of a new series of 7-methoxy indolizines as bioisostere indomethacin analogues (5a–e) were carried out and evaluated for COX-2 enzyme inhibition. All the compounds showed activity in micromolar ranges, and the compound diethyl 3-(4-cyanobenzoyl)-7-methoxyindolizine-1,2-dicarboxylate (5a) emerged as a promising COX-2 inhibitor with an IC50 of 5.84 µM, as compared to indomethacin (IC50 = 6.84 µM). The molecular modeling study of indolizines indicated that hydrophobic interactions were the major contribution to COX-2 inhibition. The title compound diethyl 3-(4-bromobenzoyl)-7-methoxyindolizine-1,2-dicarboxylate (5c) was subjected for single-crystal X-ray studies, Hirshfeld surface analysis, and energy framework calculations. The X-ray diffraction analysis showed that the molecule (5c) crystallizes in the monoclinic crystal system with space group P 21/n with a = 12.0497(6)Å, b = 17.8324(10)Å, c = 19.6052(11)Å, α = 90.000°, β = 100.372(1)°, γ = 90.000°, and V = 4143.8(4)Å3. In addition, with the help of Crystal Explorer software program using the B3LYP/6-31G(d, p) basis set, the theoretical calculation of the interaction and graphical representation of energy value was measured in the form of the energy framework in terms of coulombic, dispersion, and total energy. 相似文献
880.