全文获取类型
收费全文 | 2344篇 |
免费 | 168篇 |
国内免费 | 117篇 |
专业分类
2629篇 |
出版年
2024年 | 5篇 |
2023年 | 24篇 |
2022年 | 66篇 |
2021年 | 123篇 |
2020年 | 89篇 |
2019年 | 84篇 |
2018年 | 77篇 |
2017年 | 65篇 |
2016年 | 109篇 |
2015年 | 140篇 |
2014年 | 158篇 |
2013年 | 193篇 |
2012年 | 195篇 |
2011年 | 182篇 |
2010年 | 115篇 |
2009年 | 92篇 |
2008年 | 114篇 |
2007年 | 109篇 |
2006年 | 91篇 |
2005年 | 70篇 |
2004年 | 64篇 |
2003年 | 58篇 |
2002年 | 63篇 |
2001年 | 39篇 |
2000年 | 37篇 |
1999年 | 31篇 |
1998年 | 13篇 |
1997年 | 15篇 |
1996年 | 17篇 |
1995年 | 17篇 |
1994年 | 11篇 |
1993年 | 12篇 |
1992年 | 23篇 |
1991年 | 17篇 |
1990年 | 15篇 |
1989年 | 9篇 |
1988年 | 13篇 |
1987年 | 11篇 |
1986年 | 12篇 |
1985年 | 5篇 |
1984年 | 4篇 |
1983年 | 5篇 |
1982年 | 4篇 |
1980年 | 5篇 |
1975年 | 4篇 |
1973年 | 4篇 |
1971年 | 3篇 |
1969年 | 3篇 |
1968年 | 2篇 |
1967年 | 2篇 |
排序方式: 共有2629条查询结果,搜索用时 0 毫秒
991.
992.
Jee‐Youn Kim Yong‐Min An Won Hoon Choi Jin‐Mo Kim Samju Cho Byung Rok Yoo Jeong Wook Kang Yun‐Sil Lee Yoon‐Jin Lee Jaeho Cho 《Journal of cellular and molecular medicine》2017,21(4):711-719
Although lung injury including fibrosis is a well‐documented side effect of lung irradiation, the mechanisms underlying its pathology are poorly understood. X‐rays are known to cause apoptosis in the alveolar epithelial cells of irradiated lungs, which results in fibrosis due to the proliferation and differentiation of fibroblasts and the deposition of collagen. Apoptosis and BH3‐only pro‐apoptotic proteins have been implicated in the pathogenesis of pulmonary fibrosis. Recently, we have established a clinically analogous experimental model that reflects focal high‐dose irradiation of the ipsilateral lung. The goal of this study was to elucidate the mechanism underlying radiation‐induced lung injury based on this model. A radiation dose of 90 Gy was focally delivered to the left lung of C57BL/6 mice for 14 days. About 9 days after irradiation, the mice began to show increased levels of the pro‐apoptotic protein Noxa in the irradiated lung alongside increased apoptosis and fibrosis. Suppression of Noxa expression by small interfering RNA protected cells from radiation‐induced cell death and decreased expression of fibrogenic markers. Furthermore, we showed that reactive oxygen species participate in Noxa‐mediated, radiation‐induced cell death. Taken together, our results show that Noxa is involved in X‐ray‐induced lung injury. 相似文献
993.
994.
Fuhua?Zhao Tonggang?HouEmail author Jianxun?Wang Yijun?Jiang Shuxia?Huang Qiao?Wang Mo?Xian Xindong?MuEmail author 《Bioprocess and biosystems engineering》2017,40(1):1-7
Enzyme immobilization is believed to provide an excellent base for increasing environmental tolerance of enzyme and considerable period of time. In this work, a kind of nonporous silica nanoparticles functionalized with amino group was synthesized to immobilize proline-specific endoprotease (PSEP). PSEP is known to specifically cleave peptides (or esters) at the carboxyl side of proline, thus can prevent the formation of haze and prolong the shelf life of beer. After immobilization, the environmental tolerance (temperature and pH, respectively) was obviously improved, and the immobilized enzyme can retain above 90 % of its original activity after 6 uses. Moreover, the immobilized enzyme can effectively prevent the formation of chill-haze using fresh beer fermentation liquid. 相似文献
995.
Characterization and high‐yield production of non‐N‐glycosylated recombinant human BCMA‐Fc in Pichia pastoris 下载免费PDF全文
B‐cell maturation antigen (BCMA) fused at the C‐terminus to the Fc portion of human IgG1 (BCMA‐Fc) blocks B‐cell activating factor (BAFF) and proliferation‐inducing ligand (APRIL)‐mediated B‐cell activation, leading to immune disorders. The fusion protein has been cloned and produced by several engineering cell lines. To reduce cost and enhance production, we attempted to express recombinant human BCMA‐Fc (rhBCMA‐Fc) in Pichia pastoris under the control of the AOX1 methanol‐inducible promoter. To produce the target protein with uniform molecular weight and reduced immunogenicity, we mutated two predicted N‐linked glycosylation sites. The secretory yield was improved by codon optimization of the target gene sequence. After fed‐batch fermentation under optimized conditions, the highest yield (207 mg/L) of rhBCMA‐Fc was obtained with high productivity (3.45 mg/L/h). The purified functional rhBCMA‐Fc possessed high‐binding affinity to APRIL and dose‐dependent inhibition of APRIL‐induced proliferative activity in vitro through three‐step purification. Thus, this yeast‐derived expression method could be a low‐cost and effective alternative to the production of rhBCMA‐Fc in mammalian cell lines. 相似文献
996.
997.
Won-Young Lee Hyun-Jung Park Joon Mo Yeo Ha Yeon Jeong Hyuk Song 《Biotechnology and Bioprocess Engineering》2017,22(5):556-560
Mammary gland development is critically dependent on the interactions between its stromal and epithelial compartments. In this study, we established a co-culture of bovine mammary epithelial Mac-T cells and murine preadipocyte 3T3-L1 cells. Mac-T cells were co-cultured with 3T3-L1 cells for four days and production of milk proteins was induced for three days. After seven days of co-culturing, the number of alveolar-like colonies in the presence of 3T3-L1 cells was significantly higher than that in control group. Expression levels of αS1-casein and β-casein mRNAs were significantlyincreased by co-culturing with 3T3-L1 cells. In addition, casein protein production was significantly higher in the co-culture of Mac-T cells with 3T3-L1 cells than in control Mac-T cells. Substances that induced casein production in Mac-T cells also stimulated adipogenesis in 3T3-L1 cells. We suggest that a co-culture system of bovine mammary epithelial cells and preadipocyte cells is an efficient method for in vitro milk protein production. 相似文献
998.
Bárbara Cristina Martins Fernandes Paes Pablo Diego Moço Cristiano Gonçalves Pereira Geciane Silveira Porto Elisa Maria de Sousa Russo Luiza Cunha Junqueira Reis Dimas Tadeu Covas Virginia Picanço-Castro 《Cell biology and toxicology》2017,33(3):233-250
Ten years have passed since the first publication announcing the generation of induced pluripotent stem cells (iPSCs). Issues related to ethics, immune rejection, and cell availability seemed to be solved following this breakthrough. The development of iPSC technology allows advances in in vitro cell differentiation for cell therapy purpose and other clinical applications. This review provides a perspective on the iPSC potential for cell therapies, particularly for hematological applications. We discuss the advances in in vitro hematopoietic differentiation, the possibilities to employ iPSC in hematology studies, and their potential clinical application in hematologic diseases. The generation of red blood cells and functional T cells and the genome editing technology applied to mutation correction are also covered. We highlight some of the requirements and obstacles to be overcome before translating these cells from research to the clinic, for instance, iPSC variability, genotoxicity, the differentiation process, and engraftment. Also, we evaluate the patent landscape and compile the clinical trials in the field of pluripotent stem cells. Currently, we know much more about iPSC than in 2006, but there are still challenges that must be solved. A greater understanding of molecular mechanisms underlying the generation of hematopoietic stem cells is necessary to produce suitable and transplantable hematopoietic stem progenitor cells from iPSC. 相似文献
999.
1000.
Negative phototropism of rice root and its influencing factors 总被引:8,自引:0,他引:8
Some characteristics of the rice (Oryza sativa L.) root were found in the experiment of unilaterally irradiating the roots which were planted in water: (i) All the seminal roots, adventitious roots and their branched roots bent away from light, and their curvatures ranged from 25℃ to 60℃. The curvature of adventitious root of the higher node was often larger than that of the lower node, and even larger than that of the seminal root. (ii) The negative phototropic bending of the rice root was mainly due to the larger growth increment of root-tip cells of the irradiated side compared with that of the shaded side, (iii) Root cap was the site of light perception. If root cap was shaded while the root was irradiated the root showed no negative phototropism, and the root lost the characteristic of negative phototropism when root cap was divested. Rice root could resume the characteristic of negative phototropism when the new root cap grew up, if the original cells of root cap were well protected while root ca 相似文献