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101.
Chi YS Lee KB Kim Y Choi IS 《Langmuir : the ACS journal of surfaces and colloids》2007,23(3):1209-1214
This report describes the reactivity of acid fluoride (AF)-terminated self-assembled monolayers (SAMs) on gold toward amine and alcohol compounds and the potentiality of AF as a reactive intermediate for surface functionalizations. The AF group was generated in situ on a gold surface by reacting the terminal carboxylic acid group in the SAM of 16-mercaptohexadecanoic acid with cyanuric fluoride and pyridine under the optimized conditions. AF was found to be highly reactive toward various amine groups, such as primary and secondary amines, but it did not react effectively with alcohol. In addition, the amide coupling reaction by microcontact printing (microCP) was compared with the solution-based reaction: when amine-derivatized ferrocene compound was used for 1-min microCP on the AF-activated surface, the surface coverage of the reaction product was about 83% of 3.45 x 1014 cm-2, the coverage obtained in the solution-based reaction. On the basis of the high reaction efficiency of microCP, the AF-activated surface was also used as a platform for patterning a biological ligand, biotin. 相似文献
102.
Chi Won Kim Jungmin Ahn Sung Min Kim Tae Hwan Noh Ok-Sang Jung 《Transition Metal Chemistry》2011,36(5):545-551
Type studies on competitive polyatomic anion versus acetonitrile coordination in the self-assembly of a series of [Ag2(X)
m
(bip)(NCCH3)
n
](X)2−m
(X− = NO3
−, CF3SO3
−, ClO4
−, BF4
−, and PF6
−; m = 0, 2; n = 0, 2, 4; bip = 1,4-bis(2-isonicotinoyloxyethyl)piperazine) were carried out. Each bip spacer acts as an N4 tetradentate ligand and is linked to four silver(I) centers through two pyridine and two piperazine moieties, producing a
double strand consisting of two 20-membered ring units. The coordinating environment around the silver(I) center is subtly
determined by the competition of the polyatomic anions with acetonitrile, that is, by the Ag···NCCH3 versus Ag···X interactions. The coordinating ability of acetonitrile is inversely proportional to the order of the coordination
ability of the Hoffmeister series of polyatomic anions, NO3
− ≫ CF3SO3
− > ClO4
− > BF4
− ≫ PF6
−. 相似文献
103.
Runjiang Song Yonggui Robin Chi 《Angewandte Chemie (International ed. in English)》2019,58(26):8628-8630
N‐Heterocyclic carbene catalyzed radical reactions are challenging and underdeveloped. In a recent study, Ohmiya, Nagao and co‐workers found that aldehyde carbonyl carbon centers can be coupled with alkyl radicals under NHC catalysis. An elegant aspect of this study is the use of a redox‐active carboxylic ester that behaves as an single‐electron oxidant to convert the Breslow intermediate into a radical adduct and concurrently release an alkyl radical intermediate as a reaction partner. 相似文献
104.
Arnab Bagchi Yu‐Hsuan Huang Z. F. Xu P. Raghunath Yuan T. Lee Chi‐Kung Ni M. C. Lin Yuan‐Pern Lee 《化学:亚洲杂志》2011,6(11):2961-2976
The photodissociation of gaseous benzaldehyde (C6H5CHO) at 193, 248, and 266 nm using multimass ion imaging and step‐scan time‐resolved Fourier‐transform infrared emission techniques is investigated. We also characterize the potential energies with the CCSD(T)/6‐311+G(3df,2p) method and predict the branching ratios for various channels of dissociation. Upon photolysis at 248 and 266 nm, two major channels for formation of HCO and CO, with relative branching of 0.37:0.63 and 0.20:0.80, respectively, are observed. The C6H5+HCO channel has two components with large and small recoil velocities; the rapid component with average translational energy of approximately 25 kJ mol?1 dominates. The C6H6+CO channel has a similar distribution of translational energy for these two components. IR emission from internally excited C6H5CHO, ν3 (v=1) of HCO, and levels v≤2, J≤43 of CO are observed; the latter has an average rotational energy of approximately 13 kJ mol?1 and vibrational energy of approximately 6 kJ mol?1. Upon photolysis at 193 nm, similar distributions of energy are observed, except that the C6H5+HCO channel becomes the only major channel with a branching ratio of 0.82±0.10 and an increased proportion of the slow component; IR emission from levels ν1 (v=1) and ν3 (v=1 and 2) of HCO and v≤2, J≤43 of CO are observed; the latter has an average energy similar to that observed in photolysis at 248 nm. The observed product yields at different dissociation energies are compared to statistical‐theory predicted results based on the computed singlet and triplet potential‐energy surfaces. 相似文献
105.
Juan Gu Shao‐Ming Chi Yong Zhao Ping Zheng Qiong Ruan Yan Zhao Hong‐You Zhu 《Helvetica chimica acta》2011,94(9):1608-1617
The inclusion‐complexation behavior of coenzyme Q10 (CoQ10) with the three polyamine‐modified β‐cyclodextrins (CDs) 1 – 3 was investigated in both solution and the solid state by means of NMR, XRD, and FT‐IR spectroscopy. The results showed that the apparent solubility of CoQ10 increased linearly upon addition of hosts 1 – 3 , giving AL‐type phase‐solubility curves. These hosts 1 – 3 were able to solubilize CoQ10 to high levels, up to 1.35, 1.52, and 1.44 mg/ml (calculated as CoQ10), respectively. The host 2 with a moderate‐length chain is the most suitable for inclusion complexation of CoQ10. Accroding to the ROESY experiments, the MeO groups of CoQ10 and the tether of 2 can be co‐included into the cavity of β‐CD through the induced‐fit interaction between host and guest. The binding ability of modified β‐CDs 1 – 3 upon complexation with CoQ10 are discussed from the viewpoints of the size/shape‐matching relationship and the induced‐fit concept between host CDs and guest CoQ10 molecule. 相似文献
106.
Whereas the thermospray mass spectra of most compounds consist of only the pseudo-molecular ion with little fragmentation, the thermospray mass spectra of arteether (a cyclic endoperoxide) and its metabolites are relatively complex. Assignments of structures to individual fragments from normal spectra was particularly ambiguous because of uncertainties as to which fragments arose from ammonium ion or methanol adducts. In this study, these assignments could be resolved through the comparison of the regular spectrum with the deuterium-exchange spectrum (in an ND4O2CCH3–CD3OD–D2O mobile phase) achieved using ‘sandwiched slug’ injection technique. The mass spectra of arteether and four of its metabolites all showed [M + ND4]+ pseudo-molecular ions with greater than 91% H/D exchange, indicating a high efficiency with a minimal use of deuterated mobile phase. Most fragments showed H/D exchange rates in the 70–90% range and the isotope shift of individual spectral lines (ΔM) was found to be extremely useful in determining the structure of the fragment. 相似文献
107.
Sheng-Hung Wu Hung-Cheng Chou Ryh-Nan Pan Yi-Hao Huang Jao-Jia Horng Jen-Hao Chi Chi-Min Shu 《Journal of Thermal Analysis and Calorimetry》2012,109(1):355-364
Organic peroxides (OPs) and inorganic peroxides (IPs) are usually employed as an initiator for polymerization, a source of free radicals, a hardener, and a linking agent in low density polyethylene (LDPE), polyvinyl chloride (PVC), controlled-rheology polypropylene (CR-PP), and styrene industries. Worldwide, due to their unstably reactive natures, OPs and IPs have caused many serious thermal explosions and runaway reaction incidents. This study was conducted to elucidate its essentially hazardous characteristics. To analyze the runaway behavior of OPs and IPs in the traditional process, thermokinetic parameters including heat of decomposition (??H d ), exothermic onset temperature (T 0), self-accelerating decomposition temperature (SADT), time to maximum rate (TMR), critical temperature (T c ), etc., were measured by calorimetric approaches involving differential scanning calorimetry (DSC), vent sizing package 2 (VSP2), and calculation method. Safety and health handling information of hazardous materials and toxic substances is noted in material safety data sheets (MSDS) and was applied to analyze in process safety management (PSM) in the chemical industries, but MSDS are not providing important handling indicators concerning the SADT, TMR, T c , etc. In view of loss prevention, more useful indicators must be provided in the sheets or guide book. 相似文献
108.
The chiral phosphorus derivatizing agent (CDA) 1 was prepared from optically pure (S)‐1,1‐bis‐2‐naphthol. It was first used in the determination of the enantiomeric excess of chiral alcohols and amines by means of 31P NMR spectroscopy. It showed that, for the chiral aromatic alcohols, no apparent kinetic resolution was noted and good base‐line separation was observed. Furthermore, the chemical shift difference (Δδ) of 31P NMR spectroscopy was much larger than those determined by the use of other chiral phosphorus derivatizing agents reported previously. However, for aliphatic alcohols, it showed not only obvious kinetic resolutions but incomplete base‐line separation. Moreover, we also found that the use of CDA 1 was suitable for the determination of enantiomeric excess of chiral primary amines. © 2002 John Wiley & Sons, Inc. Heteroatom Chem 13:93–95, 2002; DOI 10.1002/hc.10018 相似文献
109.
Optical Review - Based on the planar optical theory, compact beam expanders are proposed to miniaturize the dimension of an optical system. Both simulated and experimental results have demonstrated... 相似文献
110.
Wing Chi Yu Shi-Jian Gu Hai-Qing Lin 《The European Physical Journal B - Condensed Matter and Complex Systems》2016,89(10):212
Without any knowledge of the symmetry existing in a system, we derive the exact forms of the order parameters which show long-range correlations in the ground state of the one-dimensional (1D) extended Hubbard model using a quantum information approach. Our work demonstrates that the quantum information approach can help us to find the explicit form of the order parameter, which could not be derived systematically via traditional methods in the condensed matter theory. 相似文献