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121.
Tamal Mondal C. Raghunathan K. Venkataraman 《Proceedings of the Zoological Society》2014,67(2):136-139
Reefs of Andaman and Nicobar Islands harbour 418 species of scleractinian corals spread over an area of 2,000 km2. In April to May, 2010, due to the delayed onset of the southwest monsoon the sea surface temperature of the coastal and oceanic region increased to 31.7 °C in respect to the earlier record of maximum 29.0 °C during the said period. This resulted in mass bleaching of hermatypic corals during May, 2010. Rapid under water surveys have been conducted in reefs of Andaman and Nicobar Islands to assess the health of corals between May 2010 and August 2011. It is estimated that 76.62 ± (SD) 10.83 % of coral species are bleached up to a water depth of 10–15 m. Species from the genus Acropora appeared more susceptible to bleaching than those belong to the genus Porites. During the month of June 2010 the sea surface temperature was reduced to 29 °C perhaps due to the rainfall which stimulated rebuilding of zooxanthellae population in bleached corals. Recovery of 85.54 ± (SD) 6.33 % of bleached corals was seen during the study period of 11 months after the bleaching event. Porites spp. showed a high recovery rate, while Acropora spp. had the highest mortality rate. Coral mortality can have profound ecological and socio-economical implications and highlights the need for sustained monitoring for coral reef conservation in India. Hence, steps must be taken to improve management tools to protect these resources of global significance. 相似文献
122.
Komori Y Tanaka M Kuba M Ishii M Abe M Kitamura N Verkhratsky A Shibuya I Dayanithi G 《Cell calcium》2010,48(6):324-332
Multiple mechanisms that maintain Ca(2+) homeostasis and provide for Ca(2+) signalling operate in the somatas and neurohypophysial nerve terminals of supraoptic nucleus (SON) neurones. Here, we examined the Ca(2+) clearance mechanisms of SON neurones from adult rats by monitoring the effects of the selective inhibition of different Ca(2+) homeostatic molecules on cytosolic Ca(2+) ([Ca(2+)](i)) transients in isolated SON neurones. In addition, we measured somatodendritic vasopressin (AVP) release from intact SON tissue in an attempt to correlate it with [Ca(2+)](i) dynamics. When bathing the cells in a Na(+)-free extracellular solution, thapsigargin, cyclopiazonic acid (CPA), carbonyl cyanide 3-chlorophenylhydrazone (CCCP), and the inhibitor of plasma membrane Ca(2+)-ATPase (PMCA), La(3+), all significantly slowed down the recovery of depolarisation (50 mM KCl)-induced [Ca(2+)](i) transients. The release of AVP was stimulated by 50 mM KCl, and the decline in the peptide release was slowed by Ca(2+) transport inhibitors. In contrast to previous reports, our results show that in the fully mature adult rats: (i) all four Ca(2+) homeostatic pathways, the Na(+)/Ca(2+) exchanger, the endoplasmic reticulum Ca(2+) pump, the plasmalemmal Ca(2+) pump and mitochondria, are complementary in actively clearing Ca(2+) from SON neurones; (ii) somatodendritic AVP release closely correlates with intracellular [Ca(2+)](i) dynamics; (iii) there is (are) Ca(2+) clearance mechanism(s) distinct from the four outlined above; and (iv) Ca(2+) homeostatic systems in the somatas of SON neurones differ from those expressed in their terminals. 相似文献
123.
Harris JE Govindan JA Yamamoto I Schwartz J Kaverina I Greenstein D 《Developmental biology》2006,299(1):105-121
In most animals, female meiotic spindles assemble in the absence of centrosomes; instead, microtubule nucleation by chromatin, motor activity, and microtubule dynamics drive the self-organization of a bipolar meiotic spindle. Meiotic spindle assembly commences when microtubules gain access to chromatin after nuclear envelope breakdown (NEBD) during meiotic maturation. Although many studies have addressed the chromatin-based mechanism of female meiotic spindle assembly, it is less clear how signaling influences microtubule localization and dynamics prior to NEBD. Here we analyze microtubule behavior in Caenorhabditis elegans oocytes at early stages of the meiotic maturation process using confocal microscopy and live-cell imaging. In C. elegans, sperm trigger oocyte meiotic maturation and ovulation using the major sperm protein (MSP) as an extracellular signaling molecule. We show that MSP signaling reorganizes oocyte microtubules prior to NEBD and fertilization by affecting their localization and dynamics. We present evidence that MSP signaling reorganizes oocyte microtubules through a signaling network involving antagonistic G alpha(o/i) and G alpha(s) pathways and gap-junctional communication with somatic cells of the gonad. We propose that MSP-dependent microtubule reorganization promotes meiotic spindle assembly by facilitating the search and capture of microtubules by meiotic chromatin following NEBD. 相似文献
124.
Time correlated Single Photon Counting study (TCSPC) was performed for the first time to evaluate the effect of resveratrol
(RES) and genistein (GEN) at 10–100 μM and 10–150 μM respectively, in modulating the DNA conformation and the variation induced
due to intercalation by the dyes, ethidium bromide (EtBr) and acridine orange (AO). It is demonstrated using UV-absorption
and fluorescence spectroscopy that RES and GEN, at 50 μM and 100 μM respectively can bind to DNA resulting in significant
de-intercalation of the dyes, preventing their further intercalation within DNA. Hyperchromicity with red/blue shifts in DNA
when bound to dyes was reduced upon addition of RES and GEN. DNA-dependent fluorescence of EtBr and AO was quenched in the
presence of RES by 87.97% and 79.13% respectively, while similar quenching effect was observed for these when interacted with
GEN (85.52% and 83.85%). It is found from TCSPC analysis that the higher lifetime component or constituent of intercalated
dyes (τ2, A
2) decreased with the subsequent increase in smaller component or constituent of free dye (τ1, A
1) after the interaction of drugs with the intercalated DNA. Thus these findings signify that RES and GEN can play an important
role in modulating DNA intercalation, leading to the reduction in DNA-directed toxicity. 相似文献
125.
C-phycocyanins, major biliproteins of blue green algae (cyanobacteria), widely used as colourants in food and cosmetics are known for their antioxidant as well as therapeutic potential. Recent claims indicating phycobiliproteins exert stronger photodynamic action on tumor cells than clinically approved hematoporphyrin derivatives motivate us to investigate the photodynamic action of two newly isolated C-phycocyanins from Phormidium [PHR] and Lyngbya [LY] spp, respectively in comparison with known C-phycocyanin from Spirulina sp. [SPI]. Photolysis of air saturated solutions of PHR, LY and SPI in the presence of 2,2,6,6-Tetramethyl piperidinol (TEMPL) generated three line EPR spectrum characteristic of 4-hydroxy-2,2,6,6-tetramethylpiperidinyloxyl (TEMPOL). The increase in intensity of the EPR spectrum with time of irradiation and decrease in intensity, in the presence of 1O2 quencher DABCO confirm the formation of 1O2. Photoirradiation in the presence of spin trap 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) generated EPR signal characteristic of O2(-) adduct. Efficiency of 1O2 generation is of the order LY > PHR> SPI. The yield of reactive oxygen species (ROS) generation is found to be 1O2>O2(-) indicating type II mechanism to be the prominent pathway for photosensitation by phycocyanins. 相似文献
126.
127.
BACKGROUND: A conserved biological feature of sexual reproduction in animals is that oocytes arrest in meiotic prophase and resume meiosis in response to extraovarian signals. In C. elegans, sperm trigger meiotic resumption by means of the major sperm protein (MSP) signal. MSP promotes meiotic resumption by functioning as an ephrin-signaling antagonist and by counteracting inhibitory inputs from the somatic gonadal sheath cells. RESULTS: By using a genome-wide RNAi screen in a female-sterile genetic background, we identified 17 conserved genes that maintain meiotic arrest in the absence of the MSP signal. In vitro binding experiments show that MSP promotes oocyte mitogen-activated protein kinase activation and meiotic maturation in part through direct interaction with the VAB-1 Eph receptor. Four conserved proteins, including a disabled protein (DAB-1), a vav family GEF (VAV-1), a protein kinase C (PKC-1), and a STAM homolog (PQN-19), function with the VAB-1 Eph/MSP receptor in oocytes. We show that antagonistic Galphao/i and Galphas signaling pathways function in the soma to regulate meiotic maturation in parallel to the VAB-1 pathway. Galphas activity is necessary and sufficient to promote meiotic maturation, which it does in part by antagonizing inhibitory sheath/oocyte gap-junctional communication. CONCLUSIONS: Our findings show that oocyte Eph receptor and somatic cell G protein signaling pathways control meiotic diapause in C. elegans, highlighting contrasts and parallels between MSP signaling in C. elegans and luteinizing hormone signaling in mammals. 相似文献
128.
J. Brandon Dixon Sandeep Raghunathan Melody A. Swartz 《Biotechnology and bioengineering》2009,103(6):1224-1235
Lacteals are the entry point of all dietary lipids into the circulation, yet little is known about the active regulation of lipid uptake by these lymphatic vessels, and there lacks in vitro models to study the lacteal—enterocyte interface. We describe an in vitro model of the human intestinal microenvironment containing differentiated Caco‐2 cells and lymphatic endothelial cells (LECs). We characterize the model for fatty acid, lipoprotein, albumin, and dextran transport, and compare to qualitative uptake of fatty acids into lacteals in vivo. We demonstrate relevant morphological features of both cell types and strongly polarized transport of fatty acid in the intestinal‐to‐lymphatic direction. We found much higher transport rates of lipid than of dextran or albumin across the lymphatic endothelial monolayer, suggesting most lipid transport is active and intracellular. This was confirmed with confocal imaging of Bodipy, a fluorescent fatty acid, along with transmission electron microscopy. Since our model recapitulates crucial aspects of the in vivo lymphatic–enterocyte interface, it is useful for studying the biology of lipid transport by lymphatics and as a tool for screening drugs and nanoparticles that target intestinal lymphatics. Biotechnol. Bioeng. 2009;103: 1224–1235. © 2009 Wiley Periodicals, Inc. 相似文献
129.
The nickel complexes namely bis(2-hydroxyacetophenoato)nickel(II), Ni(ohap)2 (1), bis(2-hydroxyacetophenamine)nickel(II), Ni(ohapim)2 (2) and bis(2-hydroxypropiophenamine)nickel(II), Ni(ohppim)2 (3) were synthesised in a systematic approach for the development of volatile nickel precursors for MOCVD. Upon screening these complexes by dynamic TG in an inert N2 purge gas environment, only complexes 2 and 3 were found to be completely volatile by 363 and 373 °C, respectively. These two were further characterized by FT-IR, C, H, and N and FAB-mass spectrometry. The molecular masses of the predominant Ni bearing vapour species were found to be 326 and 355 Da for 2 and 3, respectively. The complex 3 was analysed by single crystal XRD, 1H and 13C NMR. The equilibrium vapour pressures (pe) of the precursors 2 and 3 over the temperature ranges of 486-581 and 443-552 K were determined by a TG-based transpiration technique, yielding values of 130.2 (±7.2) and 113.3 (±7.5) kJ mol−1, respectively, for their standard enthalpies of sublimation (). 相似文献
130.
Murugesan Ashok Kumar Somasundaram Suji Mohan Harikrishnan Parida Ajay K Alphonse Vinoth Govindan Ganesan 《Plant Cell, Tissue and Organ Culture》2020,142(1):51-68
Plant Cell, Tissue and Organ Culture (PCTOC) - Abiotic factors like salinity, drought and cold affect agricultural productivity substantially worldwide. NAC (NAM, ATAF1/2 and CUC2) family... 相似文献