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931.
Structure of the Digestive Tube in the Holothurian Eupentacta fraudatrix (Holothuroidea: Dendrochirota) 总被引:1,自引:0,他引:1
In the holothurian Eupentacta fraudatrix,the gut wall exhibits trilaminar organization. It consists of an inner digestive epithelium, a middle layer of connective tissue, and an outer mesothelium (coelomic epithelium). The pharynx, esophagus, and stomach are lined with a cuticular epithelium composed of T-shaped cells. The lining epithelium of the intestine and cloaca lacks a cuticle and consists of columnar vesicular enterocytes. Mucocytes are also encountered in the digestive epithelium. The connective tissue layer is composed of a ground substance, which houses collagen fibers, amoebocytes, morula cells, and fibroblasts. The gut mesothelium is a pseudostratified epithelium, which is dominated by peritoneal and myoepithelial cells and also includes the perikarya and processes of the neurons of the hyponeural plexus and vacuolated cells. 相似文献
932.
933.
Identification and immunochemical characterization of a germ tube specific antigen of Candida albicans 总被引:2,自引:0,他引:2
Agnès Marot-Leblond Raymond Robert Jacques Aubry Pilar Ezcurra Jean-Marcel Senet 《FEMS immunology and medical microbiology》1993,7(2):175-186
Abstract Germ tube specific fractions of the dimorphic pathogenic fungus Candida albicans were fractionated according to their ability to link fibrinogen. These fibrinogen binding factors were used as immunogens to prepare monoclonal antibodies (mAbs) with BALB/c mice. Among the resulting mAbs, one (mAb 3D9.3) was shown by indirect immunofluorescence to be specific to the surface of the mycelial phase of the C. albicans species. No labelling of the cell wall of any other Candida species was observed. This morphological shape specificity was confirmed by immunoblotting where a polydispersed high molecular mass component was identified. The molecular mass varied with the extraction procedure used; over 210 kDa with EDTA-2ME treatment, and ranging from 110 to 220 kDa after Zymolyase digestion. This phase-specific epitope was sensitive to proteolysis with pronase E, proteinase K and trypsin, but not to periodate treatment. Further purification of this material would allow further development of new serodiagnostic assays that might be more specific for invasive disease than currently available tests. 相似文献
934.
E. O. Costa A. R. Ribeiro P. A. Melville M. S. Prada A. C. Carciofi E. T. Watanabe 《Mycopathologia》1996,135(2):85-88
The influence of different fructose concentrations (5, 3, 1 and 0 g/l) was tested on Germ Tube (GT) production by Candida albicans strain AS3P, using a Minimal Synthetic Medium (MSM) without (NH4)2SO4. The results obtained showed good GT production in the presence of all the different fructose concentrations and in the absence of any nitrogen source. The greatest GT production was obtained with 3 g/l of fructose vs 1 g/l of glucose, after 4 hr of incubation. On the other hand fructose consumption was lower than that of glucose at all concentrations over the 4 hour period. The data obtained may suggest that fructose is metabolized in a different way from glucose for GT production by C. albicans. 相似文献
935.
Joseph Lovecchio Micaela Pannella Luciana Giardino Laura Calzà Emanuele Giordano 《Biotechnology and bioengineering》2020,117(3):789-797
Cell-based in vitro biological models traditionally use monolayer cell cultures grown over plastic surfaces bathing in static media. Higher fidelity to a natural biological tissue is expected to result from growing the cells in a three-dimensional (3D) matrix. However, due to the decreased rate of diffusion inherent to increased distances within a tridimensional space, proper fluidic conditions are needed in this setting to better approximate a physiological environment. To this aim, we here propose a prototypal dynamic cell culture platform for the automatic medium replacement, via periodic perfusion flow, in a human umbilical vein endothelial cell (HUVECs) culture seeded in a Geltrex™ matrix. A state-of-the-art angiogenesis assay performed in these dynamic conditions showed sizable effects with respect to conventional static control cultures, with significantly enhanced pro-(dual antiplatelet therapy [DAPT]) and anti-(EDTA) angiogenic compound activity. In particular, dynamic culture conditions (a) enhance the 3D-organization of HUVECs into microtubule structure; (b) accelerate and improve endothelial tube formation by HUVECs in the presence of DAPT; (c) are able to completely revert the blocking effects of EDTA. These evidence emphasize the need of setting proper fluidic conditions for a better approximation of a physiological environment as an appropriate evolution of current cell culture paradigms. 相似文献
936.
Juyou Wu Zhonglin Shang Jun Wu Xueting Jiang Panagiotis N. Moschou Wending Sun Kalliopi A. Roubelakis‐Angelakis Shaoling Zhang 《The Plant journal : for cell and molecular biology》2010,63(6):1042-1053
Spermidine (Spd) has been correlated with various physiological and developmental processes in plants, including pollen tube growth. In this work, we show that Spd induces an increase in the cytosolic Ca2+ concentration that accompanies pollen tube growth. Using the whole‐cell patch clamp and outside‐out single‐channel patch clamp configurations, we show that exogenous Spd induces a hyperpolarization‐activated Ca2+ current: the addition of Spd cannot induce the channel open probability increase in excised outside‐out patches, indicating that the effect of Spd in the induction of Ca2+ currents is exerted via a second messenger. This messenger is hydrogen peroxide (H2O2), and is generated during Spd oxidation, a reaction mediated by polyamine oxidase (PAO). These reactive oxygen species trigger the opening of the hyperpolarization‐activated Ca2+‐permeable channels in pollen. To provide further evidence that PAO is in fact responsible for the effect of Spd on the Ca2+‐permeable channels, two Arabidopsis mutants lacking expression of the peroxisomal‐encoding AtPAO3 gene, were isolated and characterized. Pollen from these mutants was unable to induce the opening of the Ca2+‐permeable channels in the presence of Spd, resulting in reduced pollen tube growth and seed number. However, a high Spd concentration triggers a Ca2+ influx beyond the optimal, which has a deleterious effect. These findings strongly suggest that the Spd‐derived H2O2 signals Ca2+ influx, thereby regulating pollen tube growth. 相似文献
937.
Control of phloem unloading by action potentials in Mimosa 总被引:2,自引:0,他引:2
Jörg Fromm 《Physiologia plantarum》1991,83(3):529-533
In the sensitive plant, Mimosa pudica , action potentials arise when the leaves are touched and they trigger a sudden decrease in turgor of the pulvinar motor cells, which causes the leaf to close. These potentials may travel through the phloem and they appear to influence pulvinar phloem unloading after stimulation. Mature leaves were exposed to 14 CO2 and phloem translocation was observed by autoradiography. In unstimulated pulvini, labeled photoassimilates were restricted to the phloem. However, after stimulation, the 14 C-label appeared to be concentrated in the extensor region of the motor cortex. Since stimulation elicits an action potential, it is suggested that it also triggers phloem unloading of sucrose in the pulvini. 相似文献
938.
939.
The thalli of Lagenisma coscinodisci are coenocytic. In young thalli each nucleus is associated with two procentrioles and four dictyosomes. Before nuclear division two pairs of procentrioles are found on two opposite poles each lying in a pocket of the nuclear membranes. The spindle microtubules radiate from these poles; the nuclear membrane remains completely closed in all divisional stages. The thallus transforms holocarpically into a zoosporangium. The differentiation begins after the breakdown of the host with the formation of a cell wall and with the development of a discharge tube. During these processes peripheral dilated tubules are observed which are in close, local contact with small infoldings of the plasmalemma. The discharge tube develops independent of the point of entry of the infection tube and enlarges by tip growth. There are several light and electron microscopical observations which suggest that the last nuclear divisions in zoosporangia of old cultures are meiotic.They give rise to sexually determined zoomeiospores. 相似文献
940.
P. Bhattacharya S. K. Sen 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1980,57(4):87-90
Summary Regeneration of rice plantlets (Oryza sativa L.) from calli originated from leaf sheath cells was made possible. This was possible in tissues initially grown in media containing 2.4-D (2.4-dichlorophenoxyacetic acid) at low temperature and illumination. The slow growing tissues were subsequently subjected to growth conditions at an elevated temperature and higher illumination with addition of kinetin and IAA and without 2.4-D. The suitability of leaf sheath cells for protoplast technology is indicated by this success. 相似文献