全文获取类型
收费全文 | 2178篇 |
免费 | 91篇 |
专业分类
2269篇 |
出版年
2024年 | 4篇 |
2023年 | 11篇 |
2022年 | 38篇 |
2021年 | 48篇 |
2020年 | 27篇 |
2019年 | 51篇 |
2018年 | 57篇 |
2017年 | 36篇 |
2016年 | 86篇 |
2015年 | 118篇 |
2014年 | 126篇 |
2013年 | 160篇 |
2012年 | 216篇 |
2011年 | 206篇 |
2010年 | 134篇 |
2009年 | 108篇 |
2008年 | 163篇 |
2007年 | 149篇 |
2006年 | 92篇 |
2005年 | 95篇 |
2004年 | 80篇 |
2003年 | 65篇 |
2002年 | 42篇 |
2001年 | 29篇 |
2000年 | 30篇 |
1999年 | 26篇 |
1998年 | 8篇 |
1997年 | 7篇 |
1995年 | 5篇 |
1994年 | 2篇 |
1993年 | 5篇 |
1992年 | 9篇 |
1991年 | 4篇 |
1989年 | 3篇 |
1986年 | 3篇 |
1985年 | 2篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1980年 | 3篇 |
1977年 | 1篇 |
1976年 | 2篇 |
1975年 | 2篇 |
1973年 | 1篇 |
1970年 | 1篇 |
1969年 | 2篇 |
1968年 | 1篇 |
1967年 | 3篇 |
1966年 | 1篇 |
1965年 | 1篇 |
排序方式: 共有2269条查询结果,搜索用时 15 毫秒
991.
Ki-Beom Moon Jisu Lee Sebyung Kang Moonil Kim Hugh S. Mason Jae-Heung Jeon Hyun-Soon Kim 《Applied microbiology and biotechnology》2014,98(19):8281-8290
Based on recent developments, virus-like particles (VLPs) are considered to be perfect candidates as nanoplatforms for applications in materials science and medicine. To succeed, mass production of VLPs and self-assembly into a correct form in plant systems are key factors. Here, we report expression of synthesized coat proteins of the three viruses, Brome mosaic virus, Cucumber mosaic virus, and Maize rayado fino virus, in Nicotiana benthamiana and production of self-assembled VLPs by transient expression system using agroinfiltration. Each coat protein was synthesized and cloned into a pBYR2fp single replicon vector. Target protein expression in cells containing p19 was fourfold higher than that of cells lacking p19. After agroinfiltration, protein expression was analyzed by SDS-PAGE and quantitative image analyzer. Quantitative analysis showed that BMVCP, CMVCP, and MRFVCP concentrations were 0.5, 1.0, and 0.8 mg?·?g?1 leaf fresh weight, respectively. VLPs were purified by sucrose cushion ultracentrifugation and then analyzed by transmission electron microscopy. Our results suggested that BMVCP and CMVCP proteins expressed in N. benthamiana leaves were able to correctly self-assemble into particles. Moreover, we evaluated internal cavity accessibility of VLPs to load foreign molecules. Finally, plant growth conditions after agroinfiltration are critical for increasing heterologous protein expression levels in a transient expression system. 相似文献
992.
993.
Francis Nolan Hae-Sung Jeon 《Philosophical transactions of the Royal Society of London. Series B, Biological sciences》2014,369(1658)
Is speech rhythmic? In the absence of evidence for a traditional view that languages strive to coordinate either syllables or stress-feet with regular time intervals, we consider the alternative that languages exhibit contrastive rhythm subsisting merely in the alternation of stronger and weaker elements. This is initially plausible, particularly for languages with a steep ‘prominence gradient’, i.e. a large disparity between stronger and weaker elements; but we point out that alternation is poorly achieved even by a ‘stress-timed’ language such as English, and, historically, languages have conspicuously failed to adopt simple phonological remedies that would ensure alternation. Languages seem more concerned to allow ‘syntagmatic contrast’ between successive units and to use durational effects to support linguistic functions than to facilitate rhythm. Furthermore, some languages (e.g. Tamil, Korean) lack the lexical prominence which would most straightforwardly underpin prominence of alternation. We conclude that speech is not incontestibly rhythmic, and may even be antirhythmic. However, its linguistic structure and patterning allow the metaphorical extension of rhythm in varying degrees and in different ways depending on the language, and it is this analogical process which allows speech to be matched to external rhythms. 相似文献
994.
Cell migration requires a defined cell polarity which is formed by diverse cytoskeletal components differentially localized to the poles of cells to extracellular signals. Rap-GAP3 transiently and rapidly translocates to the cell cortex in response to chemoattractant stimulation and localizes to the leading edge of migrating cells. Here, we examined localization of truncated RapGAP3 proteins and found that the I/LWEQ domain in the central region of RapGAP3 was sufficient for posterior localization in migrating cells, as opposed to leading-edge localization of full-length Rap-GAP3. All truncated proteins accumulated at the leading edge of migrating cells exhibited clear translocation to the cell cortex in response to stimulation, whereas proteins localized to the posterior in migrating cells displayed no translocation to the cortex. The I/LWEQ domain appears to passively accumulate at the posterior region in migrating cells due to exclusion from the extended front region in response to chemoattractant stimulation rather than actively being localized to the back of cells. Our results suggest that posterior localization of the I/LWEQ domain of RapGAP3 is likely related to F-actin, which has probably different properties compared to newly formed F-actin at the leading edge of migrating cells, at the lateral and posterior regions of the cell. 相似文献
995.
Miae Jeon Hyun Jung Kwon Yong Hyun Kim Kook-Il Han Kung-Woo Nam Yeongjun Baik Sunghee Lee Wan-Jong Kim Man-Deuk Han 《Biotechnology and Bioprocess Engineering》2014,19(1):43-51
We prepared recombinant human interleukin-2 (rhIL-2) and studied its pretreated influence on liver regeneration and the blood profile in partially (67%) hepatectomized (PH) male Sprague-Dawley rats. Rats were injected in the tail vein with rhIL-2 three times per day for 3 consecutive days and 67% underwent a partial hepatectomy (PH). Five days after the PH, liver tissue and blood samples were analyzed for liver regeneration and hematological changes. The weight of the liver in the rhIL-2 pretreated groups increased in a dose-dependent manner; with the highest treatment (24 × 104 IU/kg), the maximum liver weight of 88.6% was exhibited. The control group showed a gradual increase to 76.3% of the original liver weight. A histological analysis of the liver showed an increase in proliferating cell nuclear antigen (PCNA)-positive cells in rhIL-2 pretreated rat livers. The rate of hepatocyte proliferation also increased significantly in primary cultured rat liver cells following rhIL-2 treatment. These results suggest that pretreatment with rhIL-2 may play adjuvant roles in liver regeneration after PH. 相似文献
996.
Kyung Hwa Chang Jong-Hwa Park Jeon Hwang-Bo Dae Kyun Chung Wonyong Kim In Sik Chung 《Biotechnology and Bioprocess Engineering》2014,19(5):803-810
Recombinant human cyclooxygenase-1 (COX-1) was expressed from stably transfected Trichoplusia ni BTI TN-5B1-4 (TN-5B1-4) and Drosophila melanogaster S2 cells. Two kinds of recombinant COX-1 with molecular weights (MWs) of 68 and 74 kDa were expressed in the intracellular fractions of stably transfected TN-5B1-4/ COX-1 and S2/COX-1 cells, due to glycosylation. The recombinant COX-1 secreted to medium fractions has a MW of 72 kDa. Recombinant COX-1 in the intracellular fractions was purified to homogeneity using a one-step Ni-NTA affinity fractionation method. Recombinant COX-1 purified from TN-5B1-4/COX-1 and S2/COX-1 cells contained 11,389 and 33,850 Unit/mg of specific peroxidase activity, respectively. The maximum productions of intracellular recombinant COX-1 were 1.7 and 5.6 μg/107 cells in the T-flask cultures of TN-5B1-4/COX-1 and S2/COX-1 cells, respectively. Taken together, our findings indicate that S2 cells can be more suitable system to produce recombinant COX-1, compared to TN-5B1-4 cells. 相似文献
997.
Bum Ju Ahn Hoang Le Min Wook Shin Sung-Jin Bae Eun Ji Lee Sung Yi Lee Ju Hee Yang Hee-Jun Wee Jong-Ho Cha Ji Hae Seo Hye Shin Lee Hyo-Jong Lee Ken Arai Eng H. Lo Sejin Jeon Goo Taeg Oh Woo Jean Kim Ji-Kan Ryu Jun-Kyu Suh Kyu-Won Kim 《The Journal of biological chemistry》2014,289(32):21926-21936
Ninjurin1 is involved in the pathogenesis of experimental autoimmune encephalomyelitis, an animal model of multiple sclerosis, by mediating leukocyte extravasation, a process that depends on homotypic binding. However, the precise regulatory mechanisms of Ninjurin1 during inflammation are largely undefined. We therefore examined the pro-migratory function of Ninjurin1 and its regulatory mechanisms in macrophages. Interestingly, Ninjurin1-deficient bone marrow-derived macrophages exhibited reduced membrane protrusion formation and dynamics, resulting in the impairment of cell motility. Furthermore, exogenous Ninjurin1 was distributed at the membrane of filopodial structures in Raw264.7 macrophage cells. In Raw264.7 cells, RNA interference of Ninjurin1 reduced the number of filopodial projections, whereas overexpression of Ninjurin1 facilitated their formation and thus promoted cell motility. Ninjurin1-induced filopodial protrusion formation required the activation of Rac1. In Raw264.7 cells penetrating an MBEC4 endothelial cell monolayer, Ninjurin1 was localized to the membrane of protrusions and promoted their formation, suggesting that Ninjurin1-induced protrusive activity contributed to transendothelial migration. Taking these data together, we conclude that Ninjurin1 enhances macrophage motility and consequent extravasation of immune cells through the regulation of protrusive membrane dynamics. We expect these findings to provide insight into the understanding of immune responses mediated by Ninjurin1. 相似文献
998.
999.
1000.
Virginia Edgcomb William Orsi Chesley Leslin Slava S. Epstein John Bunge Sunok Jeon Michail M. Yakimov Anke Behnke Thorsten Stoeck 《Extremophiles : life under extreme conditions》2009,13(1):151-167
Environmental factors restrict the distribution of microbial eukaryotes but the exact boundaries for eukaryotic life are not
known. Here, we examine protistan communities at the extremes of salinity and osmotic pressure, and report rich assemblages
inhabiting Bannock and Discovery, two deep-sea superhaline anoxic basins in the Mediterranean. Using a rRNA-based approach,
we detected 1,538 protistan rRNA gene sequences from water samples with total salinity ranging from 39 to 280 g/Kg, and obtained evidence that this DNA was endogenous to the extreme habitat sampled. Statistical analyses indicate that the
discovered phylotypes represent only a fraction of species actually inhabiting both the brine and the brine-seawater interface,
with as much as 82% of the actual richness missed by our survey. Jaccard indices (e.g., for a comparison of community membership)
suggest that the brine/interface protistan communities are unique to Bannock and Discovery basins, and share little (0.8–2.8%)
in species composition with overlying waters with typical marine salinity and oxygen tension. The protistan communities from
the basins’ brine and brine/seawater interface appear to be particularly enriched with dinoflagellates, ciliates and other
alveolates, as well as fungi, and are conspicuously poor in stramenopiles. The uniqueness and diversity of brine and brine-interface
protistan communities make them promising targets for protistan discovery. 相似文献