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991.
Tu WC Mühlhäusler BS James MJ Stone DA Gibson RA 《Biochemical and biophysical research communications》2012,423(1):176-182
Desaturase and elongase are two key enzyme categories in the long-chain polyunsaturated fatty acid (LCPUFA) pathway that convert dietary α-linolenic acid (18:3n-3) to docosahexaenoic acid (22:6n-3). The Δ6 desaturase is considered as rate limiting in the conversion. In a previous study in barramundi we demonstrated that the desaturase had a low Δ6 activity but noted that the enzyme also possessed Δ8 ability that utilised 20-carbon fatty acids. This observation suggests that an alternative pathway may exist in the barramundi via elongases to form 20-carbon metabolites from 18:3n-3 to 20:3n-3 and then Δ6/8 desaturase to 20:4n-3. Cloning of the barramundi elongation of very long-chain fatty acid gene (ELOVL) and heterologous expression of the corresponding elongase were performed to examine activity with regard to time course, substrate concentration and substrate preference. Results revealed that the barramundi elongase showed a broad range of substrate specificity including 18-carbon PUFA (including 18:3n-3 and 18:2n-6), 20- and 22-carbon LCPUFA, with greater activity towards omega-3 (n-3) than n-6 fatty acids. The findings from this study provide molecular evidence for an alternative n-3 fatty acid elongation pathway utilising 18:3n-3 in barramundi. 相似文献
992.
Lisa M. Stout Ruth E. Blake James P. Greenwood Anna M. Martini & Eben C. Rose 《FEMS microbiology ecology》2009,70(3):70-80
The volcanic Sulphur Springs, St. Lucia, present an extreme environment due to high temperatures, low pH values, and high concentrations of sulfate and boron. St. Lucia offers some unique geochemical characteristics that may shape the microbial communities within the Sulphur Springs area. We chose six pools representing a range of geochemical characteristics for detailed microbial community analyses. Chemical concentrations varied greatly between sites. Microbial diversity was analyzed using 16S rRNA gene clone library analyses. With the exception of one pool with relatively low concentrations of dissolved ions, microbial diversity was very low, with Aquificales sequences dominating bacterial communities at most pools. The archaeal component of all pools was almost exclusively Acidianus spp. and did not vary between sites with different chemical characteristics. In the pool with the highest boron and sulfate concentrations, only archaeal sequences were detected. Compared with other sulfur springs such as those at Yellowstone, the microbial diversity at St. Lucia is very different, but it is similar to that at the nearby Lesser Antilles island of Montserrat. While high elemental concentrations seem to be related to differences in bacterial diversity here, similarities with other Lesser Antilles sites suggest that there may be a biogeographical component as well. 相似文献
993.
Yingnan Si Seulhee Kim Eric Zhang Yawen Tang Renata Jaskula‐Sztul James M. Markert Herbert Chen Lufang Zhou Xiaoguang Liu 《Biotechnology journal》2020,15(1)
Exosomes hold great potential to deliver therapeutic reagents for cancer treatment due to its inherent low antigenicity. However, several technical barriers, such as low productivity and ineffective cancer targeting, need to be overcome before wide clinical applications. The present study aims at creating a new biomanufacturing platform of cancer‐targeted exosomes for drug delivery. Specifically, a scalable, robust, high‐yield, cell line based exosome production process is created in a stirred‐tank bioreactor, and an efficient surface tagging technique is developed to generate monoclonal antibody (mAb)‐exosomes. The in vitro characterization using transmission electron microscopy, NanoSight, and western blotting confirm the high quality of exosomes. Flow cytometry and confocal laser scanning microscopy demonstrate that mAb‐exosomes have strong surface binding to cancer cells. Furthermore, to validate the targeted drug delivery efficiency, romidepsin, a histone deacetylase inhibitor, is loaded into mAb‐exosomes. The in vitro anti‐cancer toxicity study shows high cytotoxicity of mAb‐exosome‐romidepsin to cancer cells. Finally, the in vivo study using tumor xenograft animal model validates the cancer targeting specificity, anti‐cancer efficacy, and drug delivery capability of the targeted exosomes. In summary, new techniques enabling targeted exosomes for drug delivery are developed to support large‐scale animal studies and to facilitate the translation from research to clinics. 相似文献
994.
W Zhu MS Ventevogel KJ Knilans JE Anderson LM Oldach KP McKinnon MM Hobbs GD Sempowski JA Duncan 《PloS one》2012,7(7):e41260
Neisseria gonorrhoeae is the second most common sexually transmitted bacterial pathogen worldwide. Diseases associated with N. gonorrhoeae cause localized inflammation of the urethra and cervix. Despite this inflammatory response, infected individuals do not develop protective adaptive immune responses to N. gonorrhoeae. N. gonorrhoeae is a highly adapted pathogen that has acquired multiple mechanisms to evade its host's immune system, including the ability to manipulate multiple immune signaling pathways. N. gonorrhoeae has previously been shown to engage immunosuppressive signaling pathways in B and T lymphocytes. We have now found that N. gonorrhoeae also suppresses adaptive immune responses through effects on antigen presenting cells. Using primary, murine bone marrow-derived dendritic cells and lymphocytes, we show that N. gonorrhoeae-exposed dendritic cells fail to elicit antigen-induced CD4+ T lymphocyte proliferation. N. gonorrhoeae exposure leads to upregulation of a number of secreted and dendritic cell surface proteins with immunosuppressive properties, particularly Interleukin 10 (IL-10) and Programmed Death Ligand 1 (PD-L1). We also show that N. gonorrhoeae is able to inhibit dendritic cell- induced proliferation of human T-cells and that human dendritic cells upregulate similar immunosuppressive molecules. Our data suggest that, in addition to being able to directly influence host lymphocytes, N. gonorrhoeae also suppresses development of adaptive immune responses through interactions with host antigen presenting cells. These findings suggest that gonococcal factors involved in host immune suppression may be useful targets in developing vaccines that induce protective adaptive immune responses to this pathogen. 相似文献
995.
996.
997.
SPOP Promotes Nanog Destruction to Suppress Stem Cell Traits and Prostate Cancer Progression 总被引:1,自引:0,他引:1
998.
Prey Food Quality Affects Flagellate Ingestion Rates 总被引:1,自引:3,他引:1
Flagellate feeding efficiency appears to depend on morphological characteristics of prey such as cell size and motility, as
well as on other characteristics such as digestibility and cell surface characteristics. Bacteria of varying morphological
characteristics (cell size) and mineral nutrient characteristics or food quality (as determined by the C:N:P ratio) were obtained
by growing Pseudomonas fluorescens in chemostats at four dilution rates (0.03, 0.06, 0.10, and 0.13 h−1) and three temperatures (14°C, 20°C, and 28°C). Cells of a given food quality were heat-killed and used to grow the flagellate
Ochromonas danica. Ingestion and digestion rates were determined by using fluorescently labeled bacteria of the same food quality as the bacteria
supporting growth. Ingestion rates were affected by both food quality and cell size. Cells of high food quality (low carbon:element
ratio) were ingested at higher rates than cells of low food quality. Multiple regression analysis indicated that cell size
also influenced ingestion rate but to a much lesser extent than did food quality. Digestion rates were not correlated with
either food quality or cell size. Results suggest that flagellates may adjust feeding efficiency based on the quality of food
items available. 相似文献
999.
Judith S. Weis Peddrick Weis James MacDonald Louis Pearson 《Wetlands Ecology and Management》2009,17(4):345-354
Fish use of a mangrove habitat was studied in a small mangrove forest on the West coast of Madagascar. A sand bar near the
inlet retains water in parts of the channel (pools) at low tide. Fishes in four of these pools were examined daily at all
phases of the tidal cycle for 3 weeks using underwater visual census. During week 1, fishes were diverse and abundant in all
pools: the dominant species were cardinalfish (related to Apogon
lateralis); monos, Monodactylus argenteus; black spotted snappers, Lutjanus ehrenbergi; double bar bream, Acanthopagrus bifasciatus; emperors, Lethrinus lentjan and L. sp., surgeon fish, Acanthurus nigricauda; red-lined sweetlips, Plectorhinchus plagiodesmis; and butterflyfish, Chaetodon kleini. Some species were more abundant in shaded pools; others in more open pools. During week 2 a dramatic difference was noted:
the only fishes found were schools of cardinalfish and one moray eel. This week had neap tides, with high tides in the morning
and low tides in the afternoon. As the week progressed and during week 3 (spring tides), fishes slowly repopulated the habitat
and diversity increased. Monos, absent in week 2, now had increasing numbers of small individuals. While large emperors were
scarce, small individuals appeared. The larger butterflyfish and surgeonfish seen in week 1 were replaced by small ones during
week 3. Species that had been rare in week 1 were more abundant, including pipefish and small barracudas. While species richness
increased during week 3, the community was strikingly different from that seen 2 weeks earlier. Only Pool 1, closest to the
entrance, recovered its original species richness. Abundance was much lower than in week 1. Our snapshot study apparently
captured a time when older juveniles left the mangrove forest and smaller fishes recruited into it. Utilization of this habitat
will likely vary throughout the year depending on the reproductive cycle of the different species whose juveniles utilize
it. Longer studies are needed to learn about cycles in fish use of the mangroves. 相似文献
1000.
A method employing sequential rounds of cell-free protein synthesis (CFPS) was developed to identify gene products influencing the complex metabolic systems that result in protein accumulation and folding in vitro. The first round of CFPS creates an array of cell extracts individually enriched with a single gene product expressed in-parallel from linear DNA expression templates (ETs). The cell extract is engineered to enhance template stability and to provide reaction conditions conducive for general protein activation. Following first-round expression, linear templates are selectively degraded and a plasmid template for a reporter enzyme is added to initiate a subsequent round of protein expression. Reporter concentration and activity identify first-round gene products that affect amino acid and nucleic acid stability, energy supply, protein expression, stability, and activation. This sequential CFPS system provides a unique format for the functional genomic identification of broadly diverse metabolic activities. 相似文献