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51.
The use of fluctuating asymmetry (FA) for biomonitoring environmental stress is limited by the lack of work on how FA in particular traits responds to specific stresses. Here, by manipulating the number of individuals in an enclosed fallow deer (Dama dama) population, we describe, for the first time, clear density dependence in the FA of juvenile jaw morphology. The impact of high population density on FA was strong for both sexes, supporting the use of FA for indexing environmental stress. In addition, there was some indication that the change in FA was greater in males (43.6%) than females (28.5%). Finally, the ability to buffer density-dependent stress was independent of body condition. We suggest that, under highly limiting conditions, whole cohorts may be unable to buffer against developmental error, irrespective of individual quality.  相似文献   
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Concanavalin A (ConA) is a well characterized and extensively used lectin accumulated in the protein bodies of jack bean cotyledons. ConA is synthesized as an inactive precursor proConA. The maturation of inactive proConA into biologically active ConA is a complex process including the removal of an internal glycopeptide and a C-terminal propeptide (CTPP), followed by a head-to-tail ligation of the two largest polypeptides. The cDNA encoding proConA was cloned and expressed in tobacco BY-2 cells. ProConA was slowly transported to the vacuole where its maturation into ConA was similar to that in jack bean cotyledons, apart from an incomplete final ligation. To investigate the role of the nine amino acid CTPP, a truncated form lacking the propeptide (proConADelta9) was expressed in BY-2 cells. In contrast to proConA, proConADelta9 was rapidly chased out of the endoplasmic reticulum (ER) and secreted into the culture medium. The CTPP was then fused to the C-terminal end of a secreted form of green fluorescent protein (secGFP). When expressed in tobacco BY-2 cells and leaf protoplasts, the chimaeric protein was located in the vacuole whereas secGFP was located in the culture medium and in the vacuole. Altogether, our results show we have isolated a new C-terminal vacuolar sorting determinant.  相似文献   
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BACKGROUND: Oxidized low-density lipoproteins play key roles in atherosclerosis. Their toxicity is at least in part due to 7-ketocholesterol (7KC), which is a potent inducer of apoptosis. In this study on human promonocytic U937 cells, we determined the effects and the interactions of 7KC with cellular lipids during 7KC-induced apoptosis. METHODS: Morphologic and functional changes were investigated by microscopic and flow cytometric methods after staining with propidium iodide, 3,3'-dihexyloxacarbocyanine iodide, and Hoechst 33342. Cellular lipid content was identified by using filipin to quantify free cholesterol and Nile Red (NR), which emit a yellow or orange-red fluorescence in the presence of neutral and polar lipids, respectively. After staining with NR, interactions of 7KC with cellular lipids were identified by fluorescence resonance energy transfer biphoton spectral imaging confocal microscopy and by subcellular fractionation, gas chromatography, and mass spectrometry. RESULTS: During 7KC-induced apoptosis the fluorescence from filipin and the ratio of measured (orange-red vs. yellow) fluorescence of NR were enhanced. Spectral analysis of images obtained in biphoton mode and resulting factor images demonstrated the occurrence of fluorescence resonance energy transfer between 7KC and NR and the subsequent colocalization of 7KC and NR. These data were in agreement with biochemical characterization and demonstrated that 7KC and neutral and polar lipids accumulate in NR-stained cytoplasmic structures. CONCLUSIONS: During 7KC-induced apoptosis, 7KC modifies the cellular content of neutral and polar lipids, favors free cholesterol accumulation, and colocalizes with neutral and polar lipids that are inside NR-stained cytoplasmic structures.  相似文献   
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Peroxiredoxins (Prx's) are a superfamily of thiol-specific antioxidant proteins present in all organisms and involved in the hydroperoxide detoxification of the cell. The catalytic cysteine of Prx's reduces hydroperoxides and is transformed into a transient sulfenic acid (Cys-SOH). At high hydroperoxide concentration, the sulfenic acid can be overoxidized into a sulfinate, or even a sulfonate. We present here the first peroxiredoxin characterization by solution NMR of the Saccharomyces cerevisiae alkylhydroperoxide reductase (Ahp1) in its reduced and in vitro overoxidized forms. NMR (15)N relaxation data and ultracentrifugation experiments indicate that the protein behaves principally as a homodimer (2 x 19 kDa) in solution, regardless of the redox state. In vitro treatment of Ahp1 by a large excess of tBuOOH leads to an inactive form, with the catalytic cysteine overoxidized into sulfonate, as demonstrated by (13)C NMR. Depending on the amino acid sequence of their active site, Prx's are classified into five different families. In this classification, Ahp1 is a member of the scarcely studied D-type Prx's. Ahp1 is unique among the D-type Prx's in its ability to form an intermolecular disulfide. The peptidic sequence of Ahp1 was analyzed and compared to other D-type Prx sequences.  相似文献   
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Summary The evolutionary origin of vertebrate hindbrain segmentation is unclear since the amphioxus, the closest living invertebrate relative to the vertebrates, possesses a hindbrain homolog that displays no gross morphological segmentation. Three of the estrogen-receptor related (ERR) receptors are segmentally expressed in the zebrafish hindbrain, suggesting that their common ancestor was expressed in a similar, reiterated manner. We have also cloned and determined the developmental expression of the single homolog of the vertebrate ERR genes in the amphioxus (AmphiERR). This gene is also expressed in a segmented manner in a region considered homologous to the vertebrate hindbrain. In contrast to the expression of amphioxus islet (a LIM-homeobox gene that also labels motoneurons), AmphiERR expression persists longer in the hindbrain homolog and does not later extend to additional posterior cells. In addition, AmphiERR and one of its vertebrate homologs (ERRalpha) are expressed in the developing somitic musculature of amphioxus and zebrafish, respectively. Altogether, our results are consistent with fine structural evidence suggesting that the amphioxus hindbrain is segmented, and indicate that chordate ERR gene expression is a marker for both hindbrain and muscle segmentation. Furthermore, our data support an evolution model of chordate brain segmentation: originally, the program for anterior segmentation in the protochordate ancestors of the vertebrates resided in the developing axial mesoderm which imposed reiterated patterning on the adjacent neural tube; during early vertebrate evolution, this segmentation program was transferred to and controlled by the neural tube.  相似文献   
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The first evidence that plants represent a valid, safe and cost-effective alternative to traditional expression systems for large-scale production of antigens and antibodies was described more than 10 years ago. Since then, considerable improvements have been made to increase the yield of plant-produced proteins. These include the use of signal sequences to target proteins to different cellular compartments, plastid transformation to achieve high transgene dosage, codon usage optimization to boost gene expression, and protein fusions to improve recombinant protein stability and accumulation. Thus, several HIV/SIV antigens and neutralizing anti-HIV antibodies have recently been successfully expressed in plants by stable nuclear or plastid transformation, and by transient expression systems based on plant virus vectors or Agrobacterium-mediated infection. The current article gives an overview of plant expressed HIV antigens and antibodies and provides an account of the use of different strategies aimed at increasing the expression of the accessory multifunctional HIV-1 Nef protein in transgenic plants.  相似文献   
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Candida alimentaria, Candida deformans, Candida galli, and Candida phangngensis have been recently reported to be the close relatives of Yarrowia lipolytica. To explore this clade of yeasts, we sequenced the mitochondrial genome (mtDNA) of these four species and compared it with the mtDNA of Y.?lipolytica. The five mtDNAs exhibit a similar architecture and a high level of similarity of protein coding sequences. Genome sizes are variable, ranging from 28?017?bp in C.?phangngensis to 48?508?bp in C.?galli, mainly because of the variations in intron size and number. All introns are of group I, except for a group II intron inserted in the cob gene of a single species, C.?galli. Putative endonuclease coding sequences were present in most group I introns, but also twice as free-standing ORFs in C.?galli. Phylogenetic relationships of the five species were explored using protein alignments. No close relative of the Yarrowia clade could be identified, but protein and rRNA gene orders were partially conserved in the mtDNA of Candida salmanticensis.  相似文献   
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