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991.
992.
Abstract In Intern. J. Enuiron. Anal. Chem. 66 (1989), 155-161, Roos et al.1 reported on problems encountered in the determination of 2,3,4-2′,4′,5′-hexachlorobiphenyl (CB 138) in environmental samples. These authors indicated that an interference was present for the capillary column gas chromatographic (HRGC) determination of CB 138. This interference was tentatively identified (without standard) as 2,3,5,6-3′,4′-hexachlorobiphenyl (CB 163). We have synthesized CB 163 and can confirm that it co-elutes with CB-138 on the widely used HRGC phase for polychlorinated biphenyl (PCB) analysis, 5%, phenyl, 95% methylpolysiloxane (CP-SIL8-CB) even on a 50m column. However, we managed to separate CB 163 from CB 138 on the very polar phase, bis-cyanopropylphenyl polysiloxane (SP-2330), using a 30 m column. We have quantified CB 163 and CB 138 in various environmental and technical samples and have found CB 163 to CB 138 ratios from I: 10 up to 3: 10. 相似文献
993.
P. Stoppa N. Tasinato A. Baldacci A. Pietropolli Charmet S. Giorgianni R. Wugt Larsen 《Molecular physics》2014,112(13):1799-1807
The infrared spectrum of isotopically enriched CH281BrF was investigated in the ν3 and ν8 region between 1150 and 1370 cm?1 at a resolution of 0.003 cm?1. The ν3 vibration of symmetry species A′ gives rise to an a-/b-hybrid band with a-type predominance, while the ν8 mode of A″ symmetry produces c-type absorption. Due to the proximity of the band origins to those of closely lying overtones and combination bands, the v3 = 1 and v8 = 1 levels were found perturbed through Coriolis resonance by the v5 = 2 (A′) and v6 = v9 = 1 (A″) states, respectively. The spectral analysis resulted in the identification of 3132 transitions (J″ ≤ 98 and Ka″ ≤ 14) for the ν3 and 2958 transitions (J″ ≤ 68 and Ka″ ≤ 19) for the ν8 bands. The assigned data were fitted using the Watson's A-reduction Hamiltonian in the Ir representation and the perturbation operators. Although no transitions belonging to the perturbers were observed, the band origins and excited state parameters for fundamentals and ‘dark states’ together with coupling terms for the ν3/2ν5 and ν8/ν6 + ν9 dyads were determined. 相似文献
994.
In the future, global energy balance of a Smart Grid system can be achieved by its agents deciding on their own power demand and production (locally) and the exchange of these decisions. In this paper, we develop a network model that describes how the information of power imbalance of individual agents can be exchanged in the system. Compared to existing network models with hierarchical structures, our developed model, together with a market mechanism, achieve the power balance in the system in a completely distributed way. Additionally, dynamics, constraints and forecasts of each agent can be conveniently involved. 相似文献
995.
Mette Bodekær Larsen Bibi Petersen Peter Alshede Philipsen Antony Young Elisabeth Thieden Hans Christian Wulf 《Photochemistry and photobiology》2014,90(5):1193-1198
Healthy sun habits acquired in childhood could reduce skin cancer incidence. We examined the sun exposure and protection behavior of an expected high‐exposure group of children, and the association to their parents. Open, prospective cohort study. One hundred and thirty nine participants (40 families) kept daily sun behavior diaries (sun exposure, sunscreen use, sunburns) over a 4‐month summer period (15 985 diary days). The Pigment Protection Factor (PPF), an objective measure of sun exposure, was measured at two body sites, before and after summer. All participants presented data from the same 115 days. Risk behavior (sun exposure of upper body) took place on 9.5 days (boys) and 15.6 days (girls). Sunburn and sunscreen use were infrequent. Boys’ sun exposure resulted in an increased photo protection over the study period of 1.7 SED (upper arm) and 0.8 SED (shoulder) to elicit erythema. Corresponding values for girls were as follows: 0.9 SED (upper arm) and 0.5 SED (shoulder). Boys’ sunscreen use correlated to their mothers’ (r = 0.523, P = 0.02). Girls’ number of risk days (r = 0.552, P = 0.005) and sun exposure (upper arm: r = 0.621, P < 0.001) correlated to their mothers’. The children's sun exposure was substantial. Only mothers influenced children's sun behavior and exposure. This may be of relevance in future sun protection campaigns. 相似文献
996.
997.
Billion‐Fold Enhancement in Sensitivity of Nuclear Magnetic Resonance Spectroscopy for Magnesium Ions in Solution 下载免费PDF全文
Dr. Alexander Gottberg Dr. Monika Stachura Dr. Magdalena Kowalska Dr. Mark L. Bissell Dr. Vaida Arcisauskaite Prof. Klaus Blaum Alexander Helmke Dr. Karl Johnston Dr. Kim Kreim Prof. Flemming H. Larsen Prof. Rainer Neugart Prof. Gerda Neyens Ronald F. Garcia Ruiz Daniel Szunyogh Prof. Peter W. Thulstrup Dr. Deyan T. Yordanov Prof. Lars Hemmingsen 《Chemphyschem》2014,15(18):3929-3932
β‐nuclear magnetic resonance (NMR) spectroscopy is highly sensitive compared to conventional NMR spectroscopy, and may be applied for several elements across the periodic table. β‐NMR has previously been successfully applied in the fields of nuclear and solid‐state physics. In this work, β‐NMR is applied, for the first time, to record an NMR spectrum for a species in solution. 31Mg β‐NMR spectra are measured for as few as 107 magnesium ions in ionic liquid (EMIM‐Ac) within minutes, as a prototypical test case. Resonances are observed at 3882.9 and 3887.2 kHz in an external field of 0.3 T. The key achievement of the current work is to demonstrate that β‐NMR is applicable for the analysis of species in solution, and thus represents a novel spectroscopic technique for use in general chemistry and potentially in biochemistry. 相似文献
998.
Larsen RW 《Journal of the American Chemical Society》2008,130(34):11246-11247
The present study utilizes rapid mixing techniques together with fast optical spectroscopy to probe the assembly of [Cu2(5-OH-bdc)2L2]12 formation in methanol. The data reveal five distinct kinetic steps involved in the formation of the Cu-nanoball in methanol with lifetimes of <15 ms, 26 ms, 310 ms, 4 s, and 45 s. From these results two possible mechanistic pathways are proposed based upon fragment isomerization followed by condensation. Both mechanisms involve fast building unit assembly (<15 ms) followed by either concerted or sequential fragment isomerization (activation controlled) coupled with condensation. 相似文献
999.
Achmatowicz M Thiel OR Gorins G Goldstein C Affouard C Jensen R Larsen RD 《The Journal of organic chemistry》2008,73(17):6793-6799
An efficient and scalable three-step one-pot approach to 6-methyl-5-nitroisoquinoline (1) from inexpensive 5-nitroisoquinoline, utilizing the vicarious nucleophilic substitution (VNS) as a key step, is described. The optimized reaction conditions can be applied to a limited number of other aromatic and heteroaromatic nitro compounds. Attempts to understand the observed selectivity in the VNS step led to the discovery of two new reaction pathways under VNS conditions, one leading to an isoxazole and the other resulting in the formal cyclopropanation of an aromatic nitro compound. 相似文献
1000.
Identifying significant variations in genomes can be cumbersome, as the variations span a multitude of base pairs and can make genome assembly difficult. However, large DNA molecules that span the variation aid in assembly. Due to the DNA molecule's large size, routine molecular biology techniques can break DNA. Therefore, a method is required to concentrate large DNA. A bis-acrylamide roadblock was cured in a proof-of-principle 3D printed device to concentrate DNA at the interface between the roadblock and solution. Lambda concatemer DNA was stained with YOYO-1 and loaded into the 3D printed device. A dynamic range of voltages and acrylamide concentrations were tested to determine how much DNA was concentrated and recovered. The fluorescence of the original solution and the concentrated solution was measured, the recovery was 37% of the original sample, and the volume decreased by a factor of 3 of the original volume. 相似文献