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211.
Metal(II) Ion Complexes with 5‐(Pyrazin‐2‐yl)‐2,4‐dihydro‐3H‐1,2,4‐triazole‐3‐thione; Synthesis,Structural Characterization,Acid‐base,and Complexing Properties in Solution 下载免费PDF全文
Aleksander Kufelnicki Jolanta Jaciubek‐Rosińska Marta Sobiesiak Agata Paneth Julia Jezierska Elzbieta Budzisz 《无机化学与普通化学杂志》2017,643(16):1067-1074
The study reports the synthesis of complexes Co(HL)Cl2 ( 1 ), Ni(HL)Cl2 ( 2 ), Cu(HL)Cl2 ( 3 ), and Zn(HL)3Cl2 ( 4 ) with the title ligand, 5‐(pyrazin‐2‐yl)‐1,2,4‐triazole‐5‐thione (HL), and their characterization by elemental analyses, ESI‐MS (m/z), FT‐IR and UV/Vis spectroscopy, as well as EPR in the case of the CuII complex. The comparative analysis of IR spectra of the metal ion complexes with HL and HL alone indicated that the metal ions in 1 , 2 , and 3 are chelated by two nitrogen atoms, N(4) of pyrazine and N(5) of triazole in the thiol tautomeric form, whereas the ZnII ion in 4 is coordinated by the non‐protonated N(2) nitrogen atom of triazole in the thione form. pH potentiometry and UV/Vis spectroscopy were used to examine CoII, NiII, and ZnII complexes in 10/90 (v/v) DMSO/water solution, whereas the CuII complex was examined in 40/60 (v/v) DMSO/water solution. Monodeprotonation of the thione triazole in solution enables the formation of the L:M = 1:1 species with CoII, NiII and ZnII, the 2:1 species with CoII and ZnII, and the 3:1 species with ZnII. A distorted tetrahedral arrangement of the CuII complex was suggested on the basis of EPR and Vis/NIR spectra. 相似文献
212.
Tomasz Smolinski Danuta Wawszczak Andrzej Deptula Wieslawa Lada Tadeusz Olczak Marcin Rogowski Marta Pyszynska Andrzej Grzegorz Chmielewski 《Journal of Radioanalytical and Nuclear Chemistry》2017,313(1):69-77
A micro-cloud point extraction method was discussed for preconcentration and spectrophotometric quantification of U(VI). The method depends on complex formation between U(VI) and 2-(4-sulphophenyloazo)-1,8-dihydroxy-3,6-naphtalenedisulphonic acid (SPADNS) at pH 7.0 and subsequent extraction of the complex in a mixed surfactant medium (cethyltrimethyl ammonium bromide and Triton X-114). The separation was carried out in the presence of 1% Na2SO4 at room temperature. The calibration curve was linear up to 3000 µg L?1. The enrichment factor, detection limit and precision were 16.0, 1.05 µg L?1, and 2.3%, respectively. The method was employed for the determination of U(VI) in real samples with different matrices. 相似文献
213.
Copia Lorenzo Plastino Wolfango Nisi Stefano Ciarletti Marta Povinec Pavel P. 《Journal of Radioanalytical and Nuclear Chemistry》2017,311(1):385-393
Journal of Radioanalytical and Nuclear Chemistry - Groundwater samples, collected into the deep underground facilities of Gran Sasso National Laboratory of the National Institute of Nuclear Physics... 相似文献
214.
Prof. Michael North Marta Omedes‐Pujol Courtney Williamson 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(37):11367-11375
The asymmetric addition of trimethylsilyl cyanide to aldehydes can be catalysed by Lewis acids and/or Lewis bases, which activate the aldehyde and trimethylsilyl cyanide, respectively. It is not always apparent from the structure of the catalyst whether Lewis acid or Lewis base catalysis predominates. To investigate this in the context of using salen complexes of titanium, vanadium and aluminium as catalysts, a Hammett analysis of asymmetric cyanohydrin synthesis was undertaken. When Lewis acid catalysis is dominant, a significantly positive reaction constant is observed, whereas reactions dominated by Lewis base catalysis give much smaller reaction constants. [{Ti(salen)O}2] was found to show the highest degree of Lewis acid catalysis, whereas two [VO(salen)X] (X=EtOSO3 or NCS) complexes both displayed lower degrees of Lewis acid catalysis. In the case of reactions catalysed by [{Al(salen)}2O] and triphenylphosphine oxide, a non‐linear Hammett plot was observed, which is indicative of a change in mechanism with increasing Lewis base catalysis as the carbonyl compound becomes more electron‐deficient. These results suggested that the aluminium complex/triphenylphosphine oxide catalyst system should also catalyse the asymmetric addition of trimethylsilyl cyanide to ketones and this was found to be the case. 相似文献
215.
A new cadmium(II)-imprinted polymer based on cadmium(II) 2,2′-{ethane-1,2-diylbis[nitrilo(E)methylylidene]} diphenolate-4-vinylpyridine complex was obtained via suspension polymerization. The beads were used as a minicolumn packing for flow-injection-flame atomic absorption spectrometry (FI-FAAS) determination of cadmium(II) in water samples. Sorption effectiveness was optimal within pH range of 6.6-7.7. Nitric acid, 0.5% (v/v) was used as eluent. Fast cadmium(II) sorption by the proposed material enabled to apply sample flow rates up to 10 mL min−1 without loss in sorption effectiveness. Enrichment factor (EF), concentration efficiency (CE) and limit of detection (LOD, 3σ) found for 120-s sorption time were 117, 39.1 min−1 and 0.11 μg L−1, respectively. Sorbent stability was proved for at least 100 preconcentration cycles (RSD = 2.9%). When compared to non-imprinted polymer the new Cd(II)-imprinted polymer exhibited improved selectivity towards cadmium(II) against other heavy metal ions, especially Cu(II) and Pb(II), as well as light metal ions. Accuracy of the method was tested for ground water and waste water certified reference materials and fortified water. The method was applied to Cd(II) determination in natural water samples. 相似文献
216.
Bartolomei M Carmona-Novillo E Hernández MI Campos-Martínez J Hernández-Lamoneda R 《The Journal of chemical physics》2010,133(12):124311
Completely ab initio global potential energy surfaces (PESs) for the singlet and triplet spin multiplicities of rigid O(2)((3)Σ(g)(-))+O(2)((3)Σ(g)(-)) are reported for the first time. They have been obtained by combining an accurate restricted coupled cluster theory with singles, doubles, and perturbative triple excitations [RCCSD(T)] quintet potential [Bartolomei et al., J. Chem. Phys. 128, 214304 (2008)] with complete active space second order perturbation theory (CASPT2) or, alternatively, multireference configuration interaction (MRCI) calculations of the singlet-quintet and triplet-quintet splittings. Spherical harmonic expansions, containing a large number of terms due to the high anisotropy of the interaction, have been built from the ab initio data. The radial coefficients of these expansions are matched at long range distances with analytical functions based on recent ab initio calculations of the electric properties of the monomers [M. Bartolomei, E. Carmona-Novillo, M. I. Hernández, J. Campos-Martínez, and R. Hernández-Lamoneda, J. Comput. Chem. (2010) (in press)]. The singlet and triplet PESs obtained from either RCCSD(T)-CASPT2 or RCCSD(T)-MRCI calculations are quite similar, although quantitative differences appear in specific terms of the expansion. CASPT2 calculations are the ones giving rise to larger splittings and more attractive interactions, particularly in the region of the absolute minima (in the rectangular D(2h) geometry). The new singlet, triplet, and quintet PESs are tested against second virial coefficient B(T) data and, their spherically averaged components, against integral cross sections measured with rotationally hot effusive beams. Both types of multiconfigurational approaches provide quite similar results, which, in turn, are in good agreement with the measurements. It is found that discrepancies with the experiments could be removed if the PESs were slightly more attractive. In this regard, the most attractive RCCSD(T)-CASPT2 PESs perform slightly better than the RCCSD(T)-MRCI counterpart. 相似文献
217.
Marta Worzakowska 《Journal of Thermal Analysis and Calorimetry》2010,102(2):745-750
The influence of the structure of succinic or glutaric anhydride modified linear unsaturated (epoxy) polyesters on the course
of the cure reaction with styrene initiated by benzoyl peroxide (BPO) or the mixture of benzoyl peroxide/tetrahydrophthalic
anhydride (BPO/THPA) or benzoyl peroxide/maleic anhydride, as well as viscoelastic properties and thermal behavior of their
styrene copolymers have been studied by DSC, DMA, and TGA analyses. Additionally, mechanical properties: flexural properties
using three-point bending test and Brinell’s hardness for studied copolymers were evaluated. It was confirmed that the structure
of used polyesters had a considerable influence on the course of the cure reaction with styrene, viscoelastic, thermal, and
mechanical properties of prepared styrene copolymers. Generally, one or two asymmetrical peaks for the cure reaction of succinic
or glutaric anhydride modified linear unsaturated epoxy polyesters with styrene were observed. They were connected with various
cure reaction, e.g., copolymerization of carbon–carbon double bonds of polyester with styrene, thermal curing of epoxy groups,
polyaddition reaction of epoxy to anhydride groups in dependence of used curing system. In addition, only one asymmetrical,
exothermic peak attributed to the copolymerization process of succinic or glutaric anhydride modified linear unsaturated polyesters
with styrene was visible. Moreover, the obtained styrene copolymers based on succinic or glutaric anhydride modified linear
unsaturated epoxy polyesters were characterized by higher values of
E20 °\textC¢ E_{{20\,^{\circ}{\text{C}}}}^{\prime} , T
g, E″, ν
e, E
mod, F
max, hardness, IDT, FDT but lower ε − F
max compared to those values observed for styrene copolymers prepared in the presence of succinic or glutaric anhydride modified
linear unsaturated polyesters. This supported to the production of stiffer and more thermally stable polymeric structure of
copolymers based on unsaturated epoxy polyesters. Moreover, the copolymers prepared in the use of glutaric anhydride modified
linear unsaturated (epoxy) polyesters were described by lower values of
E20 °\textC¢ E_{{20\,^{\circ}{\text{C}}}}^{\prime} , T
g, E″, ν
e, E
mod, F
max, hardness, IDT, FDT but higher ε − F
max than those based on succinic anhydride modified linear unsaturated (epoxy) polyesters. The presence of longer aliphatic chain
length in polyester’s structure leads to produce more flexible network structure of styrene copolymers based on glutaric anhydride
modified linear unsaturated (epoxy) polyesters than those based on succinic anhydride modified linear unsaturated (epoxy)
polyesters. 相似文献
218.
Edward Mikuli Marta Liszka-Skoczylas Joanna Hetmańczyk Janusz Szklarzewicz 《Journal of Thermal Analysis and Calorimetry》2010,102(3):889-897
[Mn(NH3)6](NO3)2 crystallizes in the cubic, fluorite (C1) type crystal lattice structure (Fm \( \overline{3} \) m) with a = 11.0056 Å and Z = 4. Two phase transitions of the first-order type were detected. The first registered on DSC curves as a large anomaly at T C1 h = 207.8 K and T C1 c = 207.2 K, and the second registered as a smaller anomaly at T C2 h = 184.4 K and T C2 c = 160.8 K (where the upper indexes h and c denote heating and cooling of the sample, respectively). The temperature dependence of the full width at half maximum of the band associated with the δs(HNH)F1u mode suggests that the NH3 ligands in the high temperature and intermediate phase reorientate quickly with correlation times in the order of several picoseconds and with activation energy of 9.9 kJ mol?1. In the phase transition at T C2 c probably only a some of the NH3 ligands stop their reorientation, while the remainders continue to reorientate quickly with activation energy of 7.7 kJ mol?1. Thermal decomposition of the investigated compound starts at 305 K and continues up to 525 K in four main stages (I–IV). In stage I, 2/6 of all NH3 ligands were seceded. Stages II and III are connected with an abruption of the next 2/6 and 1/6 of total NH3, respectively, and [Mn(NH3)](NO3)2 is formed. The last molecule of NH3 per formula unit is freed at stage IV together with the simultaneous thermal decomposition of the resulting Mn(NO3)2 leading to the formation of gaseous products (O2, H2O, N2 and nitrogen oxides) and solid MnO2. 相似文献
219.
Marta Worzakowska 《Journal of Thermal Analysis and Calorimetry》2010,100(2):599-605
In pseudo bi-component separated-stage model (PBSM), the effect of the TG value at separation points on the kinetic parameters is studied by residual and theoretical analysis. Simultaneously, a new method to determine the point that is the end of 1st reaction or the initial of 2nd reaction is developed. The investigations have improved the calculation procedure of PBSM. We performed thermogravimetry (TG) analysis on oil tea wood with two-step consecutive model and parallel model. Comparison between the results of the two models and improved PBSM shows well agreements. The influence of different separation points on kinetic parameters is presented. 相似文献
220.
Clara Grosso Ana Cristina Figueiredo Jesus Burillo Ana M. Mainar José S. Urieta José G. Barroso José A. Coelho António M. F. Palavra 《Journal of separation science》2010,33(14):2211-2218
Supercritical fluid extraction (SFE) of the volatile oil from Thymus vulgaris L. aerial flowering parts was performed under different conditions of pressure, temperature, mean particle size and CO2 flow rate and the correspondent yield and composition were compared with those of the essential oil isolated by hydrodistillation (HD). Both the oils were analyzed by GC and GC‐MS and 52 components were identified. The main volatile components obtained were p‐cymene (10.0–42.6% for SFE and 28.9–34.8% for HD), γ‐terpinene (0.8–6.9% for SFE and 5.1–7.0% for HD), linalool (2.3–5.3% for SFE and 2.8–3.1% for HD), thymol (19.5–40.8% for SFE and 35.4–41.6% for HD), and carvacrol (1.4–3.1% for SFE and 2.6–3.1% for HD). The main difference was found to be the relative percentage of thymoquinone (not found in the essential oil) and carvacryl methyl ether (1.0–1.2% for HD versus t?0.4 for SFE) which can explain the higher antioxidant activity, assessed by Rancimat test, of the SFE volatiles when compared with HD. Thymoquinone is considered a strong antioxidant compound. 相似文献