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N. Ragusa L. Turpeenoja G. Magri P. Lähdesmäki A. M. Giuffrida Stella 《Neurochemical research》1989,14(5):415-418
The protein composition of free mitochondria purified from cerebral cortex and striatum during aging was analyzed by gel electrophoresis. Mitochondria were isolated from cerebral cortex and striatum of 4-, 12-, and 24-month-old rat brain. The percent amount of mitochondrial proteins after gel-electrophoretic separation was determined densitometrically. A significant decrease in the amount of two polypeptides (with molecular weights of 20 and 16 kDa, respectively) in both brain regions during aging was found. The decrease was higher in the striatum indicating a greater vulnerability of this brain area to the aging process. The age-dependent modifications of mitochondrial proteins observed may play an important role in several mitochondrial functions, such as energy transduction and transport processes as well as in structural changes occurring with age, causing altered membrane permeability and fluidity. 相似文献
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The presence of species and their cover values together with soil and topographic characteristics were recorded at 40 sites along an altitudinal gradient of the Puna Belt at Pozuelos, in the High Andes in northwest Argentina. Classification and ordination of plant assemblages showed that soil and topography were the best predictors of the variation in species distribution. The different plant assemblages which occur along the topographic gradient follow the geographic variation in rainfall in this Andean region. Perennial bushes and grasses colonize the plains and slopes with fine textured soils which retain their water content. In contrast, deciduous bushes and cactuses grow on steep, rocky, dry slopes. Open woods also occur on east-facing steep, rocky slopes which are sheltered from winds. 相似文献
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Antagonists were used to investigate the role of the excitatory amino acid,l-glutamate, in the swim motor program ofHirudo medicinalis. In previous experiments, focal application ofl-glutamate or its non-NMDA agonists onto either the segmental swim-gating interneuron (cell 204) or the serotonergic Retzius cell resulted in prolonged excitation of the two cells and often in fictive swimming. Since brief stimulation of the subesophageal trigger interneuron (cell Tr1) evoked a similar response, we investigated the role of glutamate at these synapses. Kynurenic acid and two non-NMDA antagonists, 6,7-dinitroquinoxaline-2,3-dione (DNQX) and Joro spider toxin, effectively suppressed (1) the sustained activation of cell 204 and the Retzius cell following cell Tr1 stimulation and (2) the monosynaptic connection from cell Tr1 to cell 204 and the Retzius cell, but did not block spontaneous or DP nerve-activated swimming. Other glutamate blockers, including -d-glutamylaminomethyl sulfonic acid,l(+)-2-amino-3-phosphonoproprionic acid and 2-amino-5-phosphonopentanoic acid, were ineffective. DNQX also blocked both indirect excitation of cell 204 and direct depolarization of cell Tr1 in response to mechanosensory P cell stimulation. Our findings show the involvement of non-NMDA receptors in activating the swim motor program at two levels: (1) P cell input to cell Tr1 and (2) cell Tr1 input to cell 204, and reveal an essential role for glutamate in swim initiation via the cell Tr1 pathway. 相似文献
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Ana M. Celentano Gabriela Gorelik María E. Solana Leonor Sterin-Borda Enri Borda Stella M. Gonzlez Cappa 《Prostaglandins & other lipid mediators》1995,49(3)
PGE2 involvement in experimental Trypanosoma cruzi infection depends on the lethal capacity of the parasite subpopulation used. Mice acutely infected with non-lethal K98 displayed an enhancement in PGE2 serum levels during the acute period, while those infected with lethal T. cruzi subpopulations (RA or K98-2) showed levels not different from normal mice. The enhancement detected in K98 group could be related both to an increased number of CD8+ T cell number and to enhanced PGE2 release per cell by CD8+; values of PGE2 release by adherent cells were not altered in this group. Treatment with cyclooxygenase inhibitors enhanced mortality rates of mice infected with K98, and administration of 16,16-dimethyl PGE2 (dPGE) reversed this effect. However, mice infected with RA did not reduce their mortality rates by administration of diverse doses of dPGE. These findings suggest that PGE2 could play a role in resistance in mice infected with K98. 相似文献
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A systematic study of the Vernonia leopoldi complex was undertaken with the objective of determining the taxonomic status of the species involved within this group. TWo species, i.e. Vernonia leopoldi and V. bipontini have been recognized as distinct based on evidence from morphological studies accompanied by field observations and anatomical studies (particularly trichomes and petioles). Both species have 2n = 36 (first reports). Three new varieties have been recognized within V. bipontini , namely var. bipontini , var. gonderensis and var. caccaensis . A lectotype is selected for V. leopoldi . 相似文献
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A Stella N Resta M Gentile F Susca C Mareni M P Montera G Guanti 《American journal of human genetics》1993,53(5):1031-1037
Familial adenomatous polyposis (FAP) is a premalignant disease inherited as an autosomal dominant trait, characterized by hundreds to thousands of polyps in the colorectal tract. Recently, the syndrome has been shown to be caused by mutations in the APC (adenomatous polyposis coli) gene located on chromosome 5q21. We studied two families that both presented a phenotype different than that of the classical form of FAP. The most important findings observed in these two kindreds are (a) low and variable number of colonic polyps (from 5 to 100) and (b) a slower evolution of the disease, with colon cancer occurring at a more advanced age than in FAP in spite of the early onset of intestinal manifestations. To determine whether mutations of the APC gene are also responsible for this variant syndrome, linkage studies were performed by using a series of markers both intragenic and tightly linked to the APC gene. The results provide evidence for exclusion of the APC gene as the cause of the variant form of polyposis present in the two families described. 相似文献