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821.
Caspases are central players in proteolytic pathways that regulate cellular processes such as apoptosis and differentiation. To accelerate the discovery of novel caspase substrates we developed a method combining in silico screening and in vitro validation. With this approach, we identified TAF15 as a novel caspase substrate in a trial study. We find that TAF15 was specifically cleaved by caspases-3 and -7. Site-directed mutagenesis revealed the consensus sequence 106DQPD/Y110 as the only site recognized by these caspases. Surprisingly, TAF15 was cleaved at more than one site in staurosporine-treated Jurkat cells. In addition, we generated two oncogenic TAF15-CIZ/NMP4-fused proteins which have been found in acute myeloid leukemia and demonstrate that caspases-3 and -7 cleave the fusion proteins at one single site. Broad application of this combination approach should expedite identification of novel caspase-interacting proteins and provide new insights into the regulation of caspase pathways leading to cell death in normal and cancer cells.  相似文献   
822.
In the past, bile acids were considered to be just detergent molecules derived from cholesterol in the liver. They were known to be important for the solubilization of cholesterol in the gallbladder and for stimulating the absorption of cholesterol, fat-soluble vitamins, and lipids from the intestines. However, during the last two decades, it has been discovered that bile acids are regulatory molecules. Bile acids have been discovered to activate specific nuclear receptors (farnesoid X receptor, preganane X receptor, and vitamin D receptor), G protein coupled receptor TGR5 (TGR5), and cell signaling pathways (c-jun N-terminal kinase 1/2, AKT, and ERK 1/2) in cells in the liver and gastrointestinal tract. Activation of nuclear receptors and cell signaling pathways alter the expression of numerous genes encoding enzyme/proteins involved in the regulation of bile acid, glucose, fatty acid, lipoprotein synthesis, metabolism, transport, and energy metabolism. They also play a role in the regulation of serum triglyceride levels in humans and rodents. Bile acids appear to function as nutrient signaling molecules primarily during the feed/fast cycle as there is a flux of these molecules returning from the intestines to the liver following a meal. In this review, we will summarize the current knowledge of how bile acids regulate hepatic lipid and glucose metabolism through the activation of specific nuclear receptors and cell signaling pathways.  相似文献   
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Temperate terrestrial ecosystems are currently exposed to climatic and air quality changes with increased atmospheric CO2, increased temperature and prolonged droughts. The responses of natural ecosystems to these changes are focus for research, due to the potential feedbacks to the climate. We here present results from a field experiment in which the effects of these three climate change factors are investigated solely and in all combinations at a temperate heath dominated by heather (Calluna vulgaris) and wavy hair-grass (Deschampsia flexuosa).Climate induced increases in plant production may increase plant root exudation of dissolved organic compounds such as amino acids, and the release of amino acids during decomposition of organic matter. Such free amino acids in soil serve as substrates for soil microorganisms and are also acquired as nutrients directly by plants. We investigated the magnitude of the response to the potential climate change treatments on uptake of organic nitrogen in an in situ pulse labelling experiment with 15N13C2-labelled glycine (amino acid) injected into the soil.In situ root nitrogen acquisition by grasses responded significantly to the climate change treatments, with larger 15N uptake in response to warming and elevated CO2 but not additively when the treatments were combined. Also, a larger grass leaf biomass in the combined T and CO2 treatment than in individual treatments suggest that responses to combined climate change factors cannot be predicted from the responses to single factors treatments.The soil microbes were superior to plants in the short-term competition for the added glycine, as indicated by an 18 times larger 15N recovery in the microbial biomass compared to the plant biomass. The soil microbes acquired glycine largely as an intact compound (87%), with no effects of the multi factorial climate change treatment through one year.  相似文献   
826.
Quantitative proteomics using stable isotope labeling strategies combined with MS is an important tool for biomarker discovery. Methods involving stable isotope metabolic labeling result in optimal quantitative accuracy, since they allow the immediate combination of two or more samples. Unfortunately, stable isotope incorporation rates in metabolic labeling experiments using mammalian organisms usually do not reach 100%. As a consequence, protein identifications in 15N database searches have poor success rates. We report on a strategy that significantly improves the number of 15N‐labeled protein identifications and results in a more comprehensive and accurate relative peptide quantification workflow.  相似文献   
827.
The resistance of malignant cells to chemotherapy calls for the development of novel anti‐cancer drugs. TNF‐related apoptosis‐inducing ligand (TRAIL) is a pro‐apoptotic cytokine, which selectively induces apoptosis in malignant cells. We derived two TRAIL‐resistant HL‐60 subclones, HL‐60/P1 and HL‐60/P2, from a TRAIL‐sensitive HL‐60 acute promyelocytic leukemia cell line. To identify therapeutically exploitable “weaknesses” of the TRAIL‐resistant leukemia cells that could be used as molecular targets for their elimination, we performed proteomic (2‐DE) analysis and compared both TRAIL‐resistant subclones with the original TRAIL‐sensitive HL‐60 cells. We identified over 40 differentially expressed proteins. To significantly narrow the lists of candidate proteins, we excluded proteins that are known to be often differentially expressed, regardless of experiment type and tissue (the so‐called “TOP15” proteins). Decreased expression of DNA replication and maintenance proteins MCM7 and RPA32 in HL‐60/P1 cells, and the marked down‐regulation of enzyme adenosine deaminase in HL‐60/P2 cells, suggests increased sensitivity of these cells to DNA‐interfering drugs, and adenosine and its homologues, respectively. In a series of in vitro assays, we confirmed the increased toxicity of etoposide and cisplatin to TRAIL resistant HL‐60/P1 cells, and adenosine and vidarabine to HL‐60/P2, compared with TRAIL‐sensitive HL‐60 cells.  相似文献   
828.
δ15N and total nitrogen content of above- and belowground tissues of 13 plant species from two successional stages (open pioneer community and ruderal grass stage) of a dry acidic grassland in Southern Germany were analysed, in order to evaluate whether resource use partitioning by niche separation and N input by N2-fixing legumes are potential determinants for species coexistence and successional changes. Within each stage, plants from plots with different legume cover were compared. Soil inorganic N content, total plant biomass and δ15N values of bulk plant material were significantly lower in the pioneer stage than in the ruderal grass community. The observed δ15N differences were rather species- than site-specific. Within both stages, there were also species-specific differences in isotopic composition between above- and belowground plant dry matter. Species-specific δ15N signatures may theoretically be explained by (i) isotopic fractionation during microbial-mediated soil N transformations; (ii) isotopic fractionation during plant N uptake or fractionation during plant–mycorrhiza transfer processes; (iii) differences in metabolic pathways and isotopic fractionation within the plant; or (iv) partitioning of available N resources (or pools) among plant groups or differential use of the same resources by different species, which seems to be the most probable route in the present case. A significant influence of N2-fixing legumes on the N balance of the surrounding plant community was not detectable. This was confirmed by the results of an independent in situ removal experiment, showing that after 3 years there were no measurable differences in the frequency distribution between plots with and without N2-fixing legumes.  相似文献   
829.
摘要:【目的】Serpin在病原与宿主互作中起着重要的作用。本研究旨在分析在家蚕微孢子虫中的丝氨酸蛋白酶抑制剂蛋白(Serpin)的结构特征,原核克隆表达以及Western blotting检测。【方法】 基于家蚕微孢子虫全基因组序列,同源序列比对搜索获得serpin基因序列。利用在线软件分析基因的序列特征,ClustalX对氨基酸序列进行多重序列比对。构建含有GST标签的pGEX4T1-NbSPN106原核重组表达载体,在大肠杆菌BL21(DE3)诱导表达并进行纯化。纯化的重组蛋白免疫小鼠,制备抗体,并与家蚕微孢子虫总蛋白进行Western blotting免疫杂交。【结果】比对搜索在家蚕微孢子虫基因组中发现一个新的serpin基因NbSPN106。NbSPN106蛋白序列长度为384 aa,N端具有信号肽,编码一个42 kDa左右的成熟蛋白。多重序列比对说明NbSPN106具有保守的serpin位点,可能具有抑制功能。免疫杂交在家蚕微孢子虫总蛋白检测到一条45 kDa左右的特异条带。【讨论】生物信息学分析以及免疫杂交结果说明在家蚕微孢子虫中存在NbSPN106。这是在微孢子虫中首次报道发现serpin基因。对研究家蚕微孢子虫与宿主家蚕的互作具有一定的参考价值。  相似文献   
830.
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