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201.
Layne BH Duffy LM Bechtel HA Steeves AH Field RW 《The journal of physical chemistry. A》2007,111(31):7398-7403
In this article, a new technique we call Beam Action Spectroscopy via Inelastic Scattering (BASIS) is demonstrated. BASIS takes advantage of the sensitivity of rotational state distributions in a supersonic molecular beam to inelastic scattering within the beam. We exploit BASIS to achieve increased sensitivity in two very different types of experiments. In the first, the UV photodissociation spectrum of OClO is recovered by monitoring intensity changes in the pure rotational transition of a spectator molecule (OCS) downstream from the nozzle, revealing a new vibrational structure in the region between 30,000 and 36,000 cm(-1). In the second, the mid-IR vibrational spectrum of acetylene is recorded simply by monitoring a single pure rotational transition of OCS co-expanded with acetylene. The technique may prove particularly fruitful when an excitation process produces product dark states that are not easily probed by conventional spectroscopy. 相似文献
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Broersen A van Liere R Altelaar AF Heeren RM McDonnell LA 《Journal of the American Society for Mass Spectrometry》2008,19(6):823-832
High-resolution imaging mass spectrometry of large biological samples is the goal of several research groups. In mosaic imaging, the most common method, the large sample is divided into a mosaic of small areas that are then analyzed with high resolution. Here we present an automated alignment routine that uses principal component analysis to reduce the uncorrelated noise in the imaging datasets, which previously obstructed automated image alignment. An additional signal quality metric ensures that only those regions with sufficient signal quality are considered. We demonstrate that this algorithm provides superior alignment performance than manual stitching and can be used to automatically align large imaging mass spectrometry datasets comprising many individual mosaic tiles. 相似文献
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Liam M. Heaney Shuo Kang Matthew A. Turner Martin R. Lindley C. L. Paul Thomas 《Molecules (Basel, Switzerland)》2022,27(2)
Exhaled volatile organic compounds (VOCs) are of interest due to their minimally invasive sampling procedure. Previous studies have investigated the impact of exercise, with evidence suggesting that breath VOCs reflect exercise-induced metabolic activity. However, these studies have yet to investigate the impact of maximal exercise to exhaustion on breath VOCs, which was the main aim of this study. Two-litre breath samples were collected onto thermal desorption tubes using a portable breath collection unit. Samples were collected pre-exercise, and at 10 and 60 min following a maximal exercise test (VO2MAX). Breath VOCs were analysed by thermal desorption-gas chromatography-mass spectrometry using a non-targeted approach. Data showed a tendency for reduced isoprene in samples at 10 min post-exercise, with a return to baseline by 60 min. However, inter-individual variation meant differences between baseline and 10 min could not be confirmed, although the 10 and 60 min timepoints were different (p = 0.041). In addition, baseline samples showed a tendency for both acetone and isoprene to be reduced in those with higher absolute VO2MAX scores (mL(O2)/min), although with restricted statistical power. Baseline samples could not differentiate between relative VO2MAX scores (mL(O2)/kg/min). In conclusion, these data support that isoprene levels are dynamic in response to exercise. 相似文献
207.
Sacha J. Pidot Marion Herisse Liam Sharkey Liselle Atkin Jessica L. Porter Torsten Seemann Benjamin P. Howden Mark A. Rizzacasa Timothy P. Stinear 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(12):4036-4041
The nargenicin family of antibiotics are macrolides containing a rare ether‐bridged cis‐decalin motif. Several of these compounds are highly active against multi‐drug resistant organisms. Despite the identification of the first members of this family almost 40 years ago, the genetic basis for the production of these molecules and the enzyme responsible for formation of the oxa bridge, remain unknown. Here, the 85 kb nargenicin biosynthetic gene cluster was identified from a human pathogenic Nocardia arthritidis isolate and this locus is solely responsible for nargenicin production. Further investigation of this locus revealed a putative iron‐α‐ketoglutarate‐dependent dioxygenase, which was found to be responsible for the formation of the ether bridge from the newly identified deoxygenated precursor, 8,13‐deoxynargenicin. Uncovering the nargenicin biosynthetic locus provides a molecular basis for the rational bioengineering of these interesting antibiotic macrolides. 相似文献
208.
If is a partially filled‐in (0,1)‐matrix with a unique completion to a (0,1)‐matrix (with prescribed row and column sums), then we say that is a defining set for . A critical set is a minimal defining set (the deletion of any entry results in more than one completion). We give a new equivalent definition of critical sets in (0,1)‐matrices and apply this theory to , the set of (0,1)‐matrices of dimensions with uniform row and column sum . The smallest possible size for a defining set of a matrix in is [N. Cavenagh, J. Combin. Des. 21 (2013), pp. 253–266], and the infimum (the largest‐smallest defining set size for members of ) is known asymptotically [N. Cavenagh and R. Ramadurai, Linear Algebra Appl. 537 (2018), pp. 38–47]. We show that no critical set of size larger than exists in an element of and that there exists a critical set of size in an element of for each such that . We also bound the supremum (the smallest‐largest critical set size for members of ) between and . 相似文献
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