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111.
J. Raggio T. G. A. Green P. D. Crittenden A. Pintado M. Vivas S. Pérez-Ortega A. De los Ríos L. G. Sancho 《Symbiosis (Philadelphia, Pa.)》2012,56(2):55-66
Lichen species belonging to the genus Placopsis are early colonisers on snow free moraines of exposed land surfaces in the subantarctic region of Tierra de Fuego, South Chile. The physiological performance of three co-occurring species, P. pycnotheca, (terricolous), and P. perrugosa, and P. stenophylla (both saxicolous) was studied. All, possess green algal photobionts but have cyanobacteria in cephalodia. It was found that there was (i) a strong positive correlation between the acetylene reduction rate (AR) and the maximum photosynthetic rate (Amax), between the N content and the AR rate, and between the N and P contents, and (ii) the relationship between the CO2-exchange rates and the responses obtained in the laboratory reflected the ecology of these three lichens in the field. The results provide new information about the dynamics of some of the fastest growing crustose lichens. We hypothesize that the performance of these three species may have developed as a response to growing in an unstable environment that resulted from frequent glacial fluctuations. 相似文献
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Effect of unweighting on skeletal muscle use during exercise 总被引:9,自引:0,他引:9
Ploutz-Snyder L. L.; Tesch P. A.; Crittenden D. J.; Dudley G. A. 《Journal of applied physiology》1995,79(1):168-175
113.
A A Paszek LB Schook C F Louis JR Mickelson G H Flickinger J Murtaugh J R Mendiola M A Janzen C W Beattie G A Rohrer L J Alexander L Andersson H Ellegren M Johansson P Mariani L Marklund B Høyheim W Davies M Fredholm A L Archibald C S Haley 《Animal genetics》1995,26(6):377-386
Recent advances in the use of microsatellite markers and the development of comparative gene mapping techniques have made the construction of high resolution genetic maps of livestock species possible. Framework and comprehensive genetic linkage maps of porcine chromosome 6 have resulted from the first international effort to integrate genetic maps from multiple laboratories. Eleven highly polymorphic genetic markers were exchanged and mapped by four independent laboratories on a total of 583 animals derived from four reference populations. The chromosome 6 framework map consists of 10 markers ordered with high local support. The average marker interval of the framework map is 15.1 cM (sex averaged). The framework map is 135, 175 and 109 cM in length (for sex averaged, female and male maps, respectively). The comprehensive map includes a total of 48 type I and type II markers with a sex averaged interval of 3.5 cM and is 166, 196 and 126 cM (for sex averaged, female and male maps, respectively). Additional markers within framework map marker intervals can thus be selected from the comprehensive map for further analysis of quantitive trait loci (QTL) located on chromosome 6. The resulting maps of swine chromosome 6 provide a valuable tool for analysing and locating QTL. 相似文献
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Stellate ganglion stimulation (SGS) can alter lung lipids and reduce static lung compliance, although the mechanisms remain unclear. Phentolamine and propranolol were administered to anesthetized cats prior to stimulation in order to investigate SGS effects on lung lipids and compliance mediated via alpha and beta adrenergic pathways. Analysis of lung lavage revealed that SGS alone decreased cholesterol and the cholesterol/DSPC ratio which might be expected to decrease lung compliance. Alpha and beta blockade alone resulted in no changes from control in cholesterol or DSPC. Alpha blockade plus SGS yielded increased rather than decreased cholesterol and DSPC, while beta blockade prevented any change. A reduction in both static and dynamic lung compliance caused by SGS also was blocked by both alpha and beta blockade. Thus both the alpha and beta blockade prevented the SGS-induced decreases in cholesterol, cholesterol/DSPC ratio, and lung compliance. Furthermore, alpha blockade plus SGS resulted in increased TPL as well as cholesterol and DSPC. The data are consistent with the view that DSPC and cholesterol are released into the subphase by beta adrenergic mechanisms, and that their relative amounts may influence surface properties. 相似文献
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Alyssa N. Crittenden Nancy L. Conklin-Brittain David A. Zes Margaret J. Schoeninger Frank W. Marlowe 《Evolution and human behavior》2013,34(4):299-304
The longstanding view that children among foraging populations are largely dependent on the food collection efforts of others is an assumed and implicit characteristic of several models of human life history and family formation. The evolution of protracted juvenility in humans is often explained using the “embodied capital model” which argues that prolonged investment in growth and delayed reproduction evolved because a long training period is required to learn difficult foraging tasks and become a self-sufficient forager. The model suggests that if juvenile investment in growth and learning yields an increase in adult productivity, then selection will favor delayed maturity, long life span, and increased brain size. Here, we test the embodied capital model with naturalistic foraging and consumption data among juvenile Hadza hunter–gatherers of Tanzania to determine the extent to which children self-provision. We found that sex had a significant effect on both the type and the amount of food brought back to camp and consumed while out foraging; compared to their male counterparts, young female foragers consumed less while foraging and returned to camp with more food. A wide variation in caloric returns was seen across all foragers in the sample. When analyzing only food brought back to camp, age was not a significant predictor. When combining the amount of food back to camp and the amount consumed while out foraging, however, older children consistently collected more food. The data presented here suggest that although older children do appear to have greater overall foraging success, even very young children are capable of collecting a considerable amount of food. Our data, although lending support to the embodied capital model, suggest that although foraging efficiency increases with age, it remains difficult to determine if this efficiency is a byproduct of learning, strength, or perhaps individual motivation. In addition, our results indicate that juvenile self-provisioning may have played a key role in the evolution of food sharing and cooperation during hominin evolution. 相似文献