全文获取类型
收费全文 | 489篇 |
免费 | 134篇 |
出版年
2021年 | 8篇 |
2018年 | 3篇 |
2017年 | 9篇 |
2016年 | 10篇 |
2015年 | 23篇 |
2014年 | 21篇 |
2013年 | 29篇 |
2012年 | 28篇 |
2011年 | 33篇 |
2010年 | 13篇 |
2009年 | 13篇 |
2008年 | 22篇 |
2007年 | 20篇 |
2006年 | 32篇 |
2005年 | 25篇 |
2004年 | 21篇 |
2003年 | 30篇 |
2002年 | 21篇 |
2001年 | 16篇 |
2000年 | 15篇 |
1999年 | 13篇 |
1998年 | 11篇 |
1997年 | 6篇 |
1996年 | 7篇 |
1995年 | 8篇 |
1994年 | 12篇 |
1993年 | 6篇 |
1992年 | 15篇 |
1991年 | 17篇 |
1990年 | 8篇 |
1989年 | 10篇 |
1988年 | 4篇 |
1987年 | 9篇 |
1986年 | 5篇 |
1985年 | 5篇 |
1984年 | 4篇 |
1983年 | 7篇 |
1981年 | 5篇 |
1980年 | 7篇 |
1979年 | 5篇 |
1978年 | 7篇 |
1977年 | 6篇 |
1975年 | 9篇 |
1974年 | 7篇 |
1973年 | 4篇 |
1971年 | 5篇 |
1970年 | 4篇 |
1969年 | 3篇 |
1966年 | 4篇 |
1965年 | 3篇 |
排序方式: 共有623条查询结果,搜索用时 31 毫秒
1.
Jennifer Dumont Don Euwart Baisong Mei Scott Estes Rashmi Kshirsagar 《Critical reviews in biotechnology》2016,36(6):1110-1122
Biotherapeutic proteins represent a mainstay of treatment for a multitude of conditions, for example, autoimmune disorders, hematologic disorders, hormonal dysregulation, cancers, infectious diseases and genetic disorders. The technologies behind their production have changed substantially since biotherapeutic proteins were first approved in the 1980s. Although most biotherapeutic proteins developed to date have been produced using the mammalian Chinese hamster ovary and murine myeloma (NS0, Sp2/0) cell lines, there has been a recent shift toward the use of human cell lines. One of the most important advantages of using human cell lines for protein production is the greater likelihood that the resulting recombinant protein will bear post-translational modifications (PTMs) that are consistent with those seen on endogenous human proteins. Although other mammalian cell lines can produce PTMs similar to human cells, they also produce non-human PTMs, such as galactose-α1,3-galactose and N-glycolylneuraminic acid, which are potentially immunogenic. In addition, human cell lines are grown easily in a serum-free suspension culture, reproduce rapidly and have efficient protein production. A possible disadvantage of using human cell lines is the potential for human-specific viral contamination, although this risk can be mitigated with multiple viral inactivation or clearance steps. In addition, while human cell lines are currently widely used for biopharmaceutical research, vaccine production and production of some licensed protein therapeutics, there is a relative paucity of clinical experience with human cell lines because they have only recently begun to be used for the manufacture of proteins (compared with other types of cell lines). With additional research investment, human cell lines may be further optimized for routine commercial production of a broader range of biotherapeutic proteins. 相似文献
2.
The effects of 2 redox based carriers for brain directed delivery of estradiol (CDS-E2) and ethinyl estradiol (CDS-EE) on body weight were examined in rats. A single dose of CDS-E2 (3 mg/kg) decreased weight gain in castrate rats for at least 24 days. The dose response of weight gain and LH suppression were compared 12 days and 12 to 25 after CDS-E2 and CDS-EE, respectively, in ovariectomized (OVX) rats. Weight decrease was detected at a lower dose and was significant for longer after drug treatment than LH decrease. Both compounds were more potent than equimolar estradiol or estradiol valerate in reducing weight gain. Intact rats also showed decreased weight gain but were less sensitive to CDS-E2 compared to OVX rats. The effects appeared to be estrogen specific as carrier-linked testosterone had no effect on weight. The mechanisms of sustained and potent drug effects on weight are being explored. 相似文献
3.
4.
5.
Preparation and polymerization properties of monomeric ADP-actin 总被引:2,自引:0,他引:2
An improved method for the preparation of Mg-ADP-actin and Ca-ADP-actin which minimizes denaturation of the protein has been developed. Using ADP-actin prepared by this method, we have measured the polymerization characteristics of Mg-ADP-actin and Ca-ADP-actin. In contrast to the significant difference in Mg-ATP-actin and Ca-ATP-actin polymerization characteristics that we reported previously (J. Muscle Res. Cell Motility 7 (1986) 215-224), we show here that values for the critical concentration, the relative rate constant of elongation (mk+) and the relative rate constant of depolymerization (mk-) for Mg-ADP-actin are similar to those for Ca-ADP-actin. The value of mk+ for Mg-ATP-actin is about 8-fold higher than that for Mg-ADP-actin and the value of mk- for Mg-ADP-actin is 3-4-fold higher than that for Mg-ATP-actin. These factors may help explain the observation that the spontaneous nucleation rates of both types of ADP-actin are low in contrast to the rapid nucleation of Mg-ATP-actin. 相似文献
6.
7.
8.
Using miniaturized radiotelemetry to discover the breeding grounds of the endangered New Zealand Storm Petrel Fregetta maoriana 下载免费PDF全文
Matt J. Rayner Chris P. Gaskin Neil B. Fitzgerald Karen A. Baird Martin M. Berg David Boyle Leigh Joyce Todd J. Landers Graeme G. Loh Sue Maturin Lyndon Perrimen R. Paul Scofield Joanna Simm Ian Southey Graeme A. Taylor Alan J. D. Tennyson Bruce C. Robertson Megan Young Richard Walle Stefanie M. H. Ismar 《Ibis》2015,157(4):754-766
Identification of breeding sites remains a critical step in species conservation, particularly in procellariiform seabirds whose threat status is of global concern. We designed and conducted an integrative radiotelemetry approach to uncover the breeding grounds of the critically endangered New Zealand Storm Petrel Fregetta maoriana (NZSP), a species considered extinct before its rediscovery in 2003. Solar‐powered automated radio receivers and hand‐held telemetry were used to detect the presence of birds on three island groups in the Hauraki Gulf near Auckland, New Zealand. At least 11 NZSP captured and radiotagged at sea were detected at night near Te Hauturu‐o‐Toi/Little Barrier Island with the detection of an incubating bird leading to the discovery of the first known breeding site for this species. In total, four NZSP breeding burrows were detected under mature forest canopy and three adult NZSP and two NZSP chicks were ringed. Telemetry data indicated NZSP showed strong moonlight avoidance behaviour over the breeding site, had incubation shifts of approximately 5 days and had a breeding season extending from February to June/July, a different season from other Procellariiformes in the region. Radiotelemetry, in combination with rigorously collected field data on species distribution, offers a valuable technique for locating breeding grounds of procellariiform seabirds and gaining insights into breeding biology while minimizing disturbance to sensitive species or damage to fragile habitat. Our study suggests an avenue for other breeding ground searches in one of the most threatened avian Orders, and highlights the general need for information on the location of breeding sites and understanding the breeding biology in data‐deficient birds. 相似文献
9.
Integration of cell line and process development to overcome the challenge of a difficult to express protein 下载免费PDF全文
Swati Dalvi Bryan St. Germain Wenqi Xie Scott Estes Rashmi Kshirsagar Thomas Ryll 《Biotechnology progress》2015,31(5):1201-1211
This case study addresses the difficulty in achieving high level expression and production of a small, very positively charged recombinant protein. The novel challenges with this protein include the protein's adherence to the cell surface and its inhibitory effects on Chinese hamster ovary (CHO) cell growth. To overcome these challenges, we utilized a multi‐prong approach. We identified dextran sulfate as a way to simultaneously extract the protein from the cell surface and boost cellular productivity. In addition, host cells were adapted to grow in the presence of this protein to improve growth and production characteristics. To achieve an increase in productivity, new cell lines from three different CHO host lines were created and evaluated in parallel with new process development workflows. Instead of a traditional screen of only four to six cell lines in bioreactors, over 130 cell lines were screened by utilization of 15 mL automated bioreactors (AMBR) in an optimal production process specifically developed for this protein. Using the automation, far less manual intervention is required than in traditional bench‐top bioreactors, and much more control is achieved than typical plate or shake flask based screens. By utilizing an integrated cell line and process development incorporating medium optimized for this protein, we were able to increase titer more than 10‐fold while obtaining desirable product quality. Finally, Monte Carlo simulations were performed to predict the optimal number of cell lines to screen in future cell line development work with the goal of systematically increasing titer through enhanced cell line screening. © 2015 American Institute of Chemical Engineers Biotechnol. Prog., 31:1201–1211, 2015 相似文献
10.
Mark O. Kitchen Richard T. Bryan Kim E. Haworth Richard D. Emes Christopher Luscombe Lyndon Gommersall K. K. Cheng Maurice P. Zeegers Nicholas D. James Adam J. Devall Anthony A. Fryer William E. Farrell 《PloS one》2015,10(9)