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21.
Carmen V. Voogt Emmanuel Kuntsche Marloes Kleinjan Evelien A. P. Poelen Lex A. C. J. Lemmers Rutger C. M. E. Engels 《PloS one》2013,8(11)
Background
Alcohol consumption of college students has a fluctuating nature, which might impact the measurement of intervention effects. By using 25 follow-up time-points, this study tested whether intervention effects are robust or might vary over time.Methods
Data were used from a two-arm parallel group randomized controlled trial applying ecological momentary assessment (EMA) with 30 data time-points in total. Students between 18 and 24 years old who reported heavy drinking in the past six months and who were ready to change their alcohol consumption were randomly assigned to the experimental (n = 456: web-based brief alcohol intervention) and control condition (n = 451: no intervention). Outcome measures were weekly alcohol consumption, frequency of binge drinking, and heavy drinking status.Results
According to the intention-to-treat principle, regression analyses revealed that intervention effects on alcohol consumption varied when exploring multiple follow-up time-points. Intervention effects were found for a) weekly alcohol consumption at 1, 2, 3, 4, and 7 weeks follow-up, b) frequency of binge drinking at 1, 2, 7, and 12 weeks follow-up, and c) heavy drinking status at 1, 2, 7, and 16 weeks follow-up.Conclusions
This research showed that the commonly used one and six month follow-up time-points are relatively arbitrary and not using EMA might bring forth erroneous conclusions on the effectiveness of interventions. Therefore, future trials in alcohol prevention research and beyond are encouraged to apply EMA when assessing outcome measures and intervention effectiveness.Trial registration
Netherlands Trial Register NTR2665 相似文献22.
Summary The occurrence of vitellogenin in adult haploid drones of the honeybee, Apis mellifica, was determined by sensitive immunotechniques, i.e. two-dimensional Immunoelectrophoresis and SDS-PAGE immunoblotting using a monospecific anti-vitellogenin-serum. In drones vitellogenin is one of the minor fractions of the hemolymph proteins. Genetic and regulatory aspects of vitellogenin synthesis in male bees are discussed. 相似文献
23.
Eric Allan Wolfgang W. Weisser Markus Fischer Ernst-Detlef Schulze Alexandra Weigelt Christiane Roscher Jussi Baade Romain L. Barnard Holger Beßler Nina Buchmann Anne Ebeling Nico Eisenhauer Christof Engels Alexander J. F. Fergus Gerd Gleixner Marlén Gubsch Stefan Halle Alexandra M. Klein Ilona Kertscher Annely Kuu Markus Lange Xavier Le Roux Sebastian T. Meyer Varvara D. Migunova Alexandru Milcu Pascal A. Niklaus Yvonne Oelmann Esther Pašalić Jana S. Petermann Franck Poly Tanja Rottstock Alexander C. W. Sabais Christoph Scherber Michael Scherer-Lorenzen Stefan Scheu Sibylle Steinbeiss Guido Schwichtenberg Vicky Temperton Teja Tscharntke Winfried Voigt Wolfgang Wilcke Christian Wirth Bernhard Schmid 《Oecologia》2013,173(1):223-237
In order to predict which ecosystem functions are most at risk from biodiversity loss, meta-analyses have generalised results from biodiversity experiments over different sites and ecosystem types. In contrast, comparing the strength of biodiversity effects across a large number of ecosystem processes measured in a single experiment permits more direct comparisons. Here, we present an analysis of 418 separate measures of 38 ecosystem processes. Overall, 45 % of processes were significantly affected by plant species richness, suggesting that, while diversity affects a large number of processes not all respond to biodiversity. We therefore compared the strength of plant diversity effects between different categories of ecosystem processes, grouping processes according to the year of measurement, their biogeochemical cycle, trophic level and compartment (above- or belowground) and according to whether they were measures of biodiversity or other ecosystem processes, biotic or abiotic and static or dynamic. Overall, and for several individual processes, we found that biodiversity effects became stronger over time. Measures of the carbon cycle were also affected more strongly by plant species richness than were the measures associated with the nitrogen cycle. Further, we found greater plant species richness effects on measures of biodiversity than on other processes. The differential effects of plant diversity on the various types of ecosystem processes indicate that future research and political effort should shift from a general debate about whether biodiversity loss impairs ecosystem functions to focussing on the specific functions of interest and ways to preserve them individually or in combination. 相似文献
24.
25.
Smit BA Engels WJ Bruinsma J van Hylckama Vlieg JE Wouters JT Smit G 《Journal of applied microbiology》2004,97(2):306-313
AIM: Development of a fast, automated and reliable screening method for screening of large collections of bacterial strains with minimal handling time. METHODS AND RESULTS: The method is based on the injection of a small headspace sample (100 microl) from culture vials (2 ml) in 96-well format directly into the mass spectrometry (MS). A special sample tray has been developed for liquid media, and anaerobically grown cultures. In principle, all volatile components can be measured, but a representative mass fragment has to be obtained in the MS. Representative masses for 3-methylbutanal, 2-methylpropanal and benzaldehyde are 58, 72 and 105, respectively. In 1 day over 1500 samples could be analysed and the coefficient of variation for the response was <5%. CONCLUSION: Screening of 72 strains belonging to the genus Lactococcus in quadruple on the production of the key-flavour compound 3-methylbutanal illustrated the effectiveness of the method. Furthermore, knowledge of the biochemistry and physiology of 3-methylbutanal formation was used to optimize the composition of the growth medium to enhance 3-methylbutanal production, and thereby improve the screening. SIGNIFICANCE AND IMPACT OF THE STUDY: A commonly used method to control flavour formation in fermented food products is the selection of bacterial strains, which are able to produce the desired flavour compounds. As large collections of strains are available for such screenings, studying biodiversity of micro-organisms on the level of metabolic routes is strongly facilitated by highly automated high throughput screening methods for measuring enzyme activities or production of metabolites. Therefore, this method will be a useful tool for selecting flavour-producing strains and for enhancing starter culture development. 相似文献
26.
27.
Combinations of lactococcal strains from various origins with divers properties were developed as new starters for new dairy products. Flavour formation by such tailor-made cultures was studied. In some cases, a strongly enhanced flavour was observed. For instance, the combination of B1157 and SK110 strains in milk resulted in a very strong chocolate-like flavour. B1157 produces only a moderate chocolate-like flavour, whereas SK110 alone fails to produce this flavour. Headspace gas chromatography results corroborate the organoleptic evaluations. High levels of branched-chain aldehydes were found when B1157 and SK110 were grown together. The enzyme activities involved in this pathway were studied; both strains contain transaminase activity. Although B1157 had a very high amino acid decarboxylating activity, its release of amino acids from milk protein was limited. SK110 was strongly limited in decarboxylating activity, although this strain is very active in proteolysis. By combining these strains, the substrates released by SK110 can directly be used by the other strain, resulting in the completion of the whole flavour-formation pathway. This opens new avenues for the preparation of tailor-made cultures. 相似文献
28.
Strube T Schiemann O MacMillan F Prisner T Engels JW 《Nucleosides, nucleotides & nucleic acids》2001,20(4-7):1271-1274
A new facile method for spin-labeling suitable for DNA and RNA oligonucleotides is presented. The nitroxide 3-ethenyl-2,2,5,5-tetramethyl-pyrrolin-1-yloxy was directly introduced during automated solid-phase synthesis by a Pd(0) cross coupling reaction. The main advantages of this procedure are the small amount of spin-label needed for the derivatisation of the oligonucleotide and the high coupling efficiency on the solid phase. 相似文献
29.
Phenylalkyl modified phosphoramidites (alkyl chain length n = 1, 2, 3, 5; Fig. 1) were synthesised and incorporated into a DNA hexamer (5'-d(GCCp-GCG); p = place of modification). The obtained diastereomeres were separated by RP-HPLC. After hybridisation with the complementary DNA strand Tm-value and thermodynamic data were measured. The stability of duplexes depends on the linker length and the absolute configuration of the backbone modified oligodeoxynucleotides (Rp, Sp). 相似文献
30.
Six different fluorobenzene or fluorobenzimidazole ribonucleosides and one abasic site were incorporated in oligoribonucleotides. Individual contributions of base stacking and solvation of the modified nucleosides could be determined. In fluorobenzene.fluorobenzimidazole-modified base pairs a duplex stabilizing force was found that points to a weak F...H hydrogen bond. The lipophilicity of the unprotected nucleosides were investigated by determination of 1-octanol water partition coefficients. 相似文献