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431.
Anatomical evidence suggests that the dormourse is a specialist feeder. Radio-tracking and direct observation confirm this, highly selective, arboreal feeding behaviour. Dormice choose flowers and fruits from a series of trees and shrubs as each becomes seasonally available. Deferred breeding and a high incidence of diurnal torper suggest that dormice experience food shortage in spring. In early summer, when flowering has ended, but fruits are not yet ripe, dormice may again suffer food shortage. At this time they appear to supplement their diet by taking insects, another high-quality food with cyclic availability. Although some tree species are particularly valuable to dormice, they may not be essential if alternatives exist. A spectrum of species which will ensure a continuum of differeing food supplies, within a small area, is essential. This im;plies a need for heterogeneous woodland structure. The implications for conversation management are discussed. 相似文献
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433.
R. Preetha N. S. Jayaprakash Rosamma Philip I. S. Bright Singh 《Biotechnology and Bioprocess Engineering》2007,12(5):548-555
A marine isolate ofMicrococcus MCCB 104 has been identified as an aquaculture probiotic antagonistic toVibrio. In the present study different carbon and nitrogen sources and growth factors in a mineral base medium were optimized for
enhanced biomass production and antagonistic activity against the target pathogen,Vibrio harveyi, following response surface methodology (RSM). Accordingly the minimum and maximum limits of the selected variables were
determined and a set of fifty experiments programmed employing central composite design (CCD) of RSM for the final optimization.
The response surface plots of biomass showed similar pattern with that of antagonistic activity, which indicated a strong
correlation between the biomass and antagonism. The optimum concentration of the carbon sources, nitrogen sources, and growth
factors for both biomass and antagonistic activity were glucose (17.4 g/L), lactose (17 g/L), sodium chloride (16.9 g/L).
ammonium chloride (3.3 g/L), and mineral salts solution (18.3 mL/L). 相似文献
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435.
It has been repeatedly suggested that mammalian cranial sutures act not only to allow growth but also to reduce the levels of strain experienced by the skull during feeding. However, because of the added complexity they introduce, sutures are rarely included in finite element (FE) models, despite their potential to influence strain results. Because sutures present different morphologies and with differing degrees of internal fusion, many different methods of modeling may be necessary to accurately measure strain environments. Alternatively, these variables may exert very little influence on the scale of a whole‐skull model. To validate suture modeling methods, four alternative ways of including a suture in 3D FE models of the pig zygomatic arch were considered and compared with ex vivo experimental data from digital speckle pattern interferometry (DSPI). The use of DSPI rather than traditional strain gauge techniques allows strain gradients around the suture as well as the motions of the two bones to be observed. Results show that the introduction of 3D elements assigned more compliant material properties than the surrounding bone, is the most effective way of modeling both morphologies of suture, both in tension and compression. However, models containing no suture are almost indistinguishable from these compliant suture models, beyond the high strain gradient immediately adjacent to the suture. Conversely, modeling the suture as an open break in the mesh, or with spring elements assigned suture properties, fails to reproduce the experiment. Thus, although a solid but flexible model of sutures is preferred, the similarity between these models and those without sutures tentatively suggests that such extra detail may be unnecessary in pigs if the behavior of the whole skull is of interest. J. Morphol., 2011. © 2011 Wiley‐Liss, Inc. 相似文献
436.
Insolubilized coenzymes: the covalent coupling of enzymatically active NAD to glass surfaces 总被引:4,自引:0,他引:4
M K Weibel H H Weetall H J Bright 《Biochemical and biophysical research communications》1971,44(2):347-352
NAD was attached to the surface of glass beads by a diazo coupling procedure. The insolubilized NAD was shown to function as a coenzyme in the yeast alcohol dehydrogenase reaction. 相似文献
437.
Human embryonic lung fibroblasts (HEL) completed 4.5 population doublings in 6 days when maintained in DMEM supplemented with 10% human whole blood serum (WBS), plasma-derived serum (PDS) or defibrinogenated plasma containing 10 mM CaCl2. Plasma in the absence of additional calcium promoted less growth. Sera and plasma chromatographed through carboxymethyl Sephadex (CMS) supported only one population doubling. Increased growth resulting in three doublings was observed in CMS-treated WBS or PDS supplemented with commercially prepared platelet-derived growth factor (PDGF). The magnitude of this PDGF response was dependent on serum concentration. A significant increase in the proportion of cells incorporating [3H]thymidine was observed in confluent cultures exposed to PDGF prior to incubation in WBS-CMS or PDS-CMS indicating competence and progression activities for human fibroblasts. In contrast, cells maintained in the presence of plasma-CMS failed to grow in response to PDGF. Factors bound to CMS columns restored growth-promoting activity to PDGF-supplemented WBS-CMS, PDS-CMS and plasma-CMS. However, growth-promoting CMS-bound components from plasma were lost during dialysis through membranes excluding materials above 12000 MW. 相似文献
438.
Maximal lactate steady state declines during the aging process. 总被引:2,自引:0,他引:2
Craig O Mattern Margaret J Gutilla Darrin L Bright Timothy E Kirby Kenneth W Hinchcliff Steven T Devor 《Journal of applied physiology》2003,95(6):2576-2582
Increased participation of aged individuals in athletics warrants basic research focused on delineating age-related changes in performance variables. On the basis of potential age-related declines in aerobic enzyme activities and a shift in the expression of myosin heavy chain (MHC) isoforms, we hypothesized that maximal lactate steady-state (MLSS) exercise intensity would be altered as a function of age. Three age groups [young athletes (YA), 25.9 +/- 1.0 yr, middle-age athletes (MA), 43.2 +/- 1.0 yr, and older athletes (OA), 64.6 +/- 2.7 yr] of male, competitive cyclists and triathletes matched for training intensity and duration were studied. Subjects performed a maximal O2 consumption (V(o2 max)) test followed by a series of 30-min exercise trials to determine MLSS. A muscle biopsy of the vastus lateralis was procured on a separate visit. There were differences (P < 0.05) in V(o2 max) among all age groups (YA = 67.7 +/- 1.2 ml x kg-1x min-1, MA = 56.0 +/- 2.6 ml x kg-1x min-1, OA = 47.0 +/- 2.6 ml x kg-1 x min-1). When expressed as a percentage of V(o2 max), there was also an age-related decrease (P < 0.05) in the relative MLSS exercise intensity (YA = 80.8 +/- 0.9%, MA = 76.1 +/- 1.4%, OA = 69.9 +/- 1.5%). There were no significant age-related changes in citrate synthase activity or MHC isoform profile. The hypothesis is supported as there is an age-related decline in MLSS exercise intensity in athletes matched for training intensity and duration. Although type I MHC isoform, combined with age, is helpful in predicting (r = 0.76, P < 0.05) relative MLSS intensity, it does not explain the age-related decline in MLSS. 相似文献
439.
Joanne N. Bright Thomas B. Woolf Jan H. Hoh 《Progress in biophysics and molecular biology》2001,76(3):241-173
There is increasing evidence that intrinsically unstructured proteins or protein domains have important biological functions. These types of proteins may be productively analyzed using polymer theory developed to predict global physical properties of polymers. In these theories molecular detail is “coarse grained” out of the models, and replaced with a small number of parameters that characterize the polymer. This reduction in complexity allows extremely large systems to be studied. In the case of simulations, the time scales accessible also increase significantly. Here we discuss the application of polymer theory to unstructured proteins, and consider how to classify proteins within a polymer framework. We then review polymer theory that is relevant to predicting functionally important properties, such as radius of gyration, height of a polymer brush and force required to compress a polymer brush. 相似文献
440.