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71.
Coronado Tomás M. Mir Arnau Rosselló Francesc Valiente Gabriel 《Journal of mathematical biology》2019,79(3):1105-1148
Journal of Mathematical Biology - We define a new balance index for rooted phylogenetic trees based on the symmetry of the evolutive history of every set of 4 leaves. This index makes sense for... 相似文献
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A chitosan Schiff base with an aromatic aldehyde was synthesized and characterized by FTIR and NMR spectroscopies. Furthermore, the degree of substitution was calculated based on the ratios of the area of the proton of the imine (Aimine) and the area of the peak of the proton of the pyranose ring (AH-2). The antimicrobial activities were determined against bacterial and fungal strains, as well as multiple drug-resistant (MDR) bacteria. The chitosan Schiff base was also tagged with medicinal plants, for example, Curcuma longa, Peganum harmala, Lepidium sativam, and cruciferous vegetables, and the biological activities determined against pathogenic bacterial and fungal strains. The chitosan Schiff base showed maximum zone of inhibition of 22 mm against Staphylococcus aureus with a minimum zone of inhibition of 15 mm against Bacillus cereus. The chitosan Schiff base was fused with C longa, isothiocyanates and a combined mixture of P harmala and L sativam that has shown activities against Escherichia coli with a zone of inhibition of 28, 24, and 30 mm, respectively. The Schiff base of chitosan fused with medicinal plants also showed significant inhibitory activities against MDR bacteria. 相似文献
74.
Recent studies demonstrated that deglycosylation step is a prerequisite for endoplasmic reticulum (ER)-associated degradation of misfolded glycoproteins. Here, we report the advantages of using benzyl mannose during pulse-chase experiments to study the subcellular location of the deglycosylation step in Chinese hamster ovary (CHO) cell lines. Benzyl mannose inhibited both the ER-to-cytosol transport of oligomannosides and the trimming of cytosolic-labeled oligomannosides by the cytosolic mannosidase in vivo. We pointed out the occurrence of two subcellular sites of deglycosylation. The first one is located in the ER lumen, and led to the formation of Man8GlcNAc2 (isomer B) in wild-type CHO cell line and Man4GlcNAc2 in Man-P-Dol-deficient cell line. The second one was revealed in CHO mutant cell lines for which a high rate of glycoprotein degradation was required. It occurred in the cytosol and led to the liberation of oligosaccharides species with one GlcNAc residue and with a pattern similar to the one bound onto glycoproteins. The cytosolic deglycosylation site was not specific for CHO mutant cell lines, since we demonstrated the occurrence of cytosolic pathway when the formation of truncated glycans was induced in wild-type cells. 相似文献
75.
Ali MH Pearlstein DP Mathieu CE Schumacker PT 《American journal of physiology. Lung cellular and molecular physiology》2004,287(3):L486-L496
Mechanical strain triggers a variety of cellular responses, but the underlying mechanotransduction process has not been established. Endothelial cells (EC) respond to mechanical strain by upregulating adhesion molecule expression through a signaling process involving reactive oxygen species (ROS), but the site of their generation is unknown. Mitochondria anchor to the cytoskeleton and could function as mechanotransducers by releasing ROS during cytoskeletal strain. In human umbilical vein EC (HUVEC), ROS production increased 221 +/- 17% during 6 h of cyclic strain vs. unstrained controls. Mitochondrial inhibitors diphenylene iodonium or rotenone abrogated this response, whereas inhibitors of nitric oxide (NO) synthase (L-nitroarginine), xanthine oxidase (allopurinol), or NAD(P)H oxidase (apocynin) had no effect. The antioxidants ebselen and diethyldithiocarbamate inhibited the increase in ROS, but the NO scavenger Hb had no effect. Thus strain induces ROS release from mitochondria. In other studies, HUVEC were rendered mitochondria deficient (rho0 EC) to determine the requirement for electron transport in the response to strain. Strain-induced 2'7'-dichlorofluorescein fluorescence was attenuated by >80% in rho0 EC compared with HUVEC (43 +/- 7 vs. 221 +/- 17%). Treatment with cytochalasin D abrogated strain-induced ROS production, indicating a requirement for the actin cytoskeleton. Cyclic strain (6 h) increased VCAM-1 expression in wild-type but not rho0 EC. Increases in NF-kappaB activation and VCAM-1 mRNA expression during strain were prevented by antioxidants. These findings demonstrate that mitochondria function as mechanotransducers in endothelium by increasing ROS signaling, which is required for strain-induced increase in VCAM-1 expression via NF-kappaB. 相似文献
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The hammerhead ribozyme is able to cleave RNA in a sequence-specific manner. These ribozymes are usually designed with four
basepairs in helix II, and with equal numbers of nucleotides in the 5′ and 3′ hybridizing arms that bind the RNA substrate
on either side of the cleavage site. Here guidelines are given for redesigning the ribozyme so that it is small, but retains
efficient cleavage activity. First, the ribozyme may be reduced in size by shortening the 5′ arm of the ribozyme to five or
six nucleotides; for these ribozymes, cleavage of short substrates is maximal. Second, the internal double-helix of the ribozyme
(helix II) may be shortened to one or no basepairs, forming a miniribozyme or minizyme, respectively. The sequence of the
shortened helix+loop II greatly affects cleavage rates. With eight or more nucleotides in both the 5′ and the 3′ arms of a
miniribozyme containing an optimized sequence for helix+loop II, cleavage rates of short substrates are greater than for analogous
ribozymes possessing a longer helix II. Cleavage of genelength RNA substrates may be best achieved by miniribozymes. 相似文献
79.
Summary The precise geometry of pro-centriole formation has been studied inPhysarum polycephalum amoebae. The spatial references used were the posterior and the anterior kinetosomes which are unequivocally defined by the presence of the posterior para-kinetosomal structure, the microtubular array 4 and the microtubular arrays 1, 2, and 3. The observations made suggest that pro-centrioles follow a maturation process. A pro-centriole formed during the nth cell cycle becomes the posterior kinetosome during the (n + 1)th cell cycle and the anterior one during all the following cell cycles. Pro-centriole formation occurs late in the cell cycle. This observation disagrees with a role of pro-centriole formation in the regulation of S phase in contrast to what has been suggested in other eucaryotic cells. 相似文献
80.
César Garriga Patricia García de Olalla Josep M. Miró Inma Oca?a Hernando Knobel Maria Jesús Barberá Victoria Humet Pere Domingo Josep M. Gatell Esteve Ribera Mercè Gurguí Andrés Marco Joan A. Caylà 《PloS one》2015,10(12)