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431.
Avijit Lahiri 《Bio Systems》1977,9(1):57-68
The concepts of structural and functional approaches are analysed. The existence of a logical limit to the domain of applicability of the structural approach is indicated. Some sources of possible failure of the structural method in biology are pointed out. Two fundamental characteristics of biological systems, inductive development and inductive functioning. necessitating the functional approach, are discussed. 相似文献
432.
Carbonic anhydrase and chemoreception in the cat carotid body 总被引:2,自引:0,他引:2
433.
S Lahiri T Nishino E Mulligan A Mokashi 《Journal of applied physiology (Bethesda, Md. : 1985)》1980,48(2):362-369
Discharges from aortic and carotid body chemoreceptor afferents were simultaneously recorded in 18 anesthetized cats to test the hypothesis that aortic chemoreceptors, because of their proximity to the heart, respond to changes in arterial blood gases before carotid chemoreceptors. We found that carotid chemoreceptor responses to the onset of hypoxia and hypercapnia, and to the intravenously administered excitatory drugs (cyanide, nicotine, and doxapram), preceded those of aortic chemoreceptors. Postulating that this unexpected result was due to differences in microcirculation and mass transport, we also investigated their relative speed of responses to changes in arterial blood pressure. The aortic chemoreceptors responded to decreases in arterial blood pressure before the carotid chemoreceptors, supporting the idea that the aortic body has microcirculatory impediments not generally present in the carotid body. These findings strengthened the concept that carotid bodies are more suited for monitoring blood gas changes due to respiration, whereas aortic bodies are for monitoring circulation. 相似文献
434.
The effects of foliar application of morphactin (0, 10, 50 and 100 ppm) onPennisetum typhoides (cv. HB3) have been studied under different soil moisture conditions (0.3, 3 and 9 x 10Pa tension). Morphactin application reduced the plant height, increased the tillering and leaf number of the main shoot and adversely affected the growth characters associated with the grain production. The overall performance of plants was not improved by morphactin treatment under low moisture regime and it did not impart any efficiency of water use for grain production. Findings on the phosphorus and potassium levels of the shoot tissue suggested a possibility of its interference in the nutrient uptake process. 相似文献
435.
In the present investigation the sequential expression and organization of keratin intermediate filament proteins were studied
in the developing rat palatal epithelia starting from early gestation period to the adult. The distribution and organization
of keratin proteins were correlated with the formation and elaboration of desmosornes during differentiation and stratification
of the epithelia. 相似文献
436.
437.
Fertilizer induced improvement of growth and yield of wheat (Triticum aestivum L. cv. Kalyan Sona), under salinity stress, was associated with an increase in the concentrations of nitrogen, phosphorus
and potassium and a decrease in the level of chloride in the tissue. The concentration of chloride in grains was also reduced
under high fertility as compared to low fertility condition. Results reveal that under both normal and saline conditions,
nutritional improvement leads to higher chlorophyll concentration and increased efficiency of enzymes like nitrate reductase,
ATPase, alkaline pyrophosphatase and amylase in the leaves. This imparts importance to fertilizer application under saline
conditions. 相似文献
438.
I R Moss M Denavit-Saubié F L Eldridge R A Gillis M Herkenham S Lahiri 《Federation proceedings》1986,45(7):2133-2147
The respiratory control system is influenced by classical neurotransmitters and by neuromodulators. The neuromodulators are neuroactive substances that can be secreted at a distance from their receptors and must diffuse to their site of action. Their function can be nonsynaptic and long lasting, and their effect can be direct or indirect via other neuroactive substances. In the central nervous system, a variable degree of mismatch exists between sites of neuromodulator secretion and reception. The assignment of a natural role for a neuromodulator in respiratory control is strengthened by evidence from a variety of experimental approaches, including localization of receptor sites in respiratory-related areas and evidence for natural binding of neuromodulators to these receptors, neurophysiological and respiratory responses to the neuromodulators and their antagonists, and, finally, modulation of specific respiratory responses by neuromodulator antagonists to document the role of the endogenous modulator in eliciting the original response. Neuromodulators that are considered seriously as natural participants in respiratory control include dopamine in peripheral chemoreception and adenosine, endorphins (including enkephalins), serotonin, and substance P in central respiratory regulation. 相似文献
439.
S Lahiri J S Brody E K Motoyama T M Velasquez 《Journal of applied physiology (Bethesda, Md. : 1985)》1978,44(5):673-678
Resting respiratory parameters and respiratory responses to acute changes in end-tidal O2 and CO2 pressure (PETO2 and PETCO2) were investigated in Peru in 23 newborn and 4 older infants at 3.850 m and in 13 newborns at 800 m. The study was done with the subjects asleep in a thermoneutral environment. The transient increase in ventilation in both high- and low-altitude newborns was followed by a decrease in response to acute hypoxia. During hyperoxia the two groups showed a slight but not clearly significant decrease in ventilation, whereas older high-altitude infants showed a sustained decrease. All subjects showed a prompt and clear response to CO2 inhalation during hyperoxia. We conclude that ventilatory peripheral chemoreflex is not fully developed in newborns regardless of altitude. The weak link in the reflex arc may reside in the afferent component because CO2 response was not impaired. Since hypoxic response became persistent in older infants its blunting in adult high-altitude natives is not a legacy of newborns. 相似文献
440.