全文获取类型
收费全文 | 824篇 |
免费 | 55篇 |
国内免费 | 6篇 |
专业分类
885篇 |
出版年
2024年 | 2篇 |
2023年 | 3篇 |
2022年 | 24篇 |
2021年 | 30篇 |
2020年 | 25篇 |
2019年 | 13篇 |
2018年 | 32篇 |
2017年 | 37篇 |
2016年 | 55篇 |
2015年 | 61篇 |
2014年 | 59篇 |
2013年 | 83篇 |
2012年 | 55篇 |
2011年 | 73篇 |
2010年 | 43篇 |
2009年 | 34篇 |
2008年 | 26篇 |
2007年 | 26篇 |
2006年 | 24篇 |
2005年 | 28篇 |
2004年 | 15篇 |
2003年 | 14篇 |
2002年 | 14篇 |
2001年 | 4篇 |
2000年 | 9篇 |
1999年 | 9篇 |
1998年 | 9篇 |
1997年 | 5篇 |
1996年 | 8篇 |
1995年 | 3篇 |
1994年 | 6篇 |
1993年 | 2篇 |
1992年 | 5篇 |
1991年 | 3篇 |
1990年 | 3篇 |
1989年 | 4篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1985年 | 3篇 |
1984年 | 2篇 |
1983年 | 3篇 |
1982年 | 4篇 |
1976年 | 4篇 |
1972年 | 4篇 |
1969年 | 1篇 |
1968年 | 2篇 |
1966年 | 1篇 |
1965年 | 1篇 |
1939年 | 1篇 |
排序方式: 共有885条查询结果,搜索用时 0 毫秒
21.
Rehab Mohammad Yusif Irhan Ibrahim Abu Hashim Elham Abdelmonem Mohamed Farid Abd-Elreheim Badria 《AAPS PharmSciTech》2016,17(2):328-338
Currently available anti-ulcer drugs suffer from serious side effects which limited their uses and prompted the need to search for a safe and efficient new anti-ulcer agent. Boswellia gum resin (BR) emerged as a safe, efficient, natural, and economic potential cytoprotective agent. Thus, it is of medical importance to develop gastroretentive (GR) formulations of BR to enhance its bioavailability and anti-ulcer efficacy. Early attempts involved the use of organic solvents and non-applicability to large-scale production. In this study, different tablet formulations were prepared by simple direct compression combining floating and bioadhesion mechanisms employing hydroxypropyl methylcellulose (HPMC), sodium carboxymethyl cellulose (SCMC), pectin (PC), and/or carbopol (CP) as bioadhesive polymers and sodium bicarbonate (SB) as a gas former. The prepared tablets were subjected for assessment of swelling, floating, bioadhesion, and drug release in 0.1 N HCl. The optimized GR formulation was examined for its protective effect on the gastric ulcer induced by indomethacin in albino rabbits compared with lactose tablets. The obtained results disclosed that swelling, floating, bioadhesion, and drug release of the GR tablets of BR depend mainly on the nature of the matrix and the ratio of polymer combinations. Moreover, a combination of SCMC-CP in a ratio of 2:1 (SCP21) exhibited desirable floating, bioadhesion, swelling, and extended drug release. Also, a 6-h pretreatment with SCP21 tablets decreased the severity of inflammation and number of bleeding spots among ulcer-induced rabbits in comparison to those treated with lactose tablets. 相似文献
22.
23.
Ahmad Abu Turab Naqvi Mohamed F. Alajmi Tabish Rehman Md Afzal Hussain Imtaiyaz Hassan Md 《Journal of cellular biochemistry》2019,120(10):17847-17857
Glycoprotein Ibα (GpIbα) binding ability of A1 domain of von Willebrand factor (vWF) facilitates platelet adhesion that plays a crucial role in maintaining hemostasis and thrombosis at the site of vascular damage. There are both “loss as well as gain of function” mutations observed in this domain. Naturally occurring “gain of function” mutations leave self-activating impacts on the A1 domain which turns the normal binding to characteristic constitutive binding with GPIbα. These “gain of function” mutations are associated with the von Willebrand disease type 2B. In recent years, studies focused on understanding the mechanism and conformational patterns attached to these phenomena have been conducted, but the conformational pathways leading to such binding patterns are poorly understood as of now. To obtain a microscopic picture of such events for the better understanding of pathways, we used molecular dynamics (MD) simulations along with principal component analysis and normal mode analysis to study the effects of Pro1266Leu (Pro503Leu in structural context) mutation on the structure and function of A1 domain of vWF. MD simulations have provided atomic-level details of intermolecular motions as a function of time to understand the dynamic behavior of A1 domain of vWF. Comparative analysis of the trajectories obtained from MD simulations of both the wild type and Pro503Leu mutant suggesting appreciable conformational changes in the structure of mutant which might provide a basis for assuming the “gain of function” effects of these mutations on the A1 domain of vWF, resulting in the constitutive binding with GpIbα. 相似文献
24.
25.
26.
27.
Irin Parvin Abu Sadat Mohammad Sayeem Bin Shahid Subhasish Das Lubaba Shahrin Mst. Mahmuda Ackhter Tahmina Alam Soroar Hossain Khan Mohammod Jobayer Chisti John D. Clemens Tahmeed Ahmed David A. Sack Abu Syed Golam Faruque 《PLoS neglected tropical diseases》2021,15(9)
BackgroundAfter a multi-country Asian outbreak of cholera due to Vibrio cholerae serogroup O139 which started in 1992, it is rarely detected from any country in Asia and has not been detected from patients in Africa.Methodology/Principal findingsWe extracted surveillance data from the Dhaka and Matlab Hospitals of International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b) to review trends in isolation of Vibrio cholerae O139 in Bangladesh. Data from the Dhaka Hospital is a 2% sample of > 100,000 diarrhoeal patients treated annually. Data from the Matlab Hospital includes all diarrhoeal patients who hail from the villages included in the Matlab Health and Demographic Surveillance System. Vibrio cholerae O139 was first isolated in Dhaka in 1993 and had been isolated every year since then except for a gap between 2005 and 2008. An average of thirteen isolates was detected annually from the Dhaka Hospital during the last ten years, yielding an estimated 650 cases annually at this hospital. During the last ten years, cases due to serogroup O139 represented 0.47% of all cholera cases; the others being due to serogroup O1. No cases with serogroup O139 were identified at Matlab since 2006. Clinical signs and symptoms of cholera due to serogroup O139 were similar to cases due to serogroup O1 though more of the O139 cases were not dehydrated. Most isolates of O139 remained sensitive to tetracycline, ciprofloxacin, and azithromycin, but they became resistant to erythromycin starting in 2009.Conclusions/SignificanceCholera due to Vibrio cholerae serogroup O139 continues to cause typical cholera in Dhaka, Bangladesh. 相似文献
28.
Combined metabolomics and proteomics reveals hypoxia as a cause of lower productivity on scale‐up to a 5000‐liter CHO bioprocess 下载免费PDF全文
Yuanwei Gao Somak Ray Shujia Dai Alexander R. Ivanov Nicholas R. Abu‐Absi Amanda M. Lewis Zhuangrong Huang Zizhuo Xing Michael C. Borys Zheng Jian Li Barry L. Karger 《Biotechnology journal》2016,11(9):1190-1200
Large‐scale bioprocessing is key to the successful manufacturing of a biopharmaceutical. However, cell viability and productivity are often lower in the scale‐up from laboratory to production. In this study, we analyzed CHO cells, which showed lower percent viabilities and productivity in a 5‐KL production scale bioreactor compared to a 20‐L bench‐top scale under seemingly identical process parameters. An increase in copper concentration in the media from 0.02 µM to 0.4 µM led to a doubling of percent viability in the production scale albeit still at a lower level than the bench‐top scale. Combined metabolomics and proteomics revealed the increased copper reduced the presence of reactive oxygen species (ROS) in the 5‐KL scale process. The reduction in oxidative stress was supported by the increased level of glutathione peroxidase in the lower copper level condition. The excess ROS was shown to be due to hypoxia (intermittent), as evidenced by the reduction in fibronectin with increased copper. The 20‐L scale showed much less hypoxia and thus less excess ROS generation, resulting in little to no impact to productivity with the increased copper in the media. The study illustrates the power of 'Omics in aiding in the understanding of biological processes in biopharmaceutical production. 相似文献
29.
30.
Gui-Hua Jin Yan-Li Zhou Hong Yang Yan-Ting Hu Yong Shi Ling Li Abu N. Siddique Chang-Ning Liu An-Dan Zhu Cheng-Jun Zhang De-Zhu Li 《植物分类学报:英文版》2021,59(2):341-351
Orphan genes are genetic innovations that lack homologs in other lineages. Orphan genes can rapidly originate and become substantially functional, yet the mechanisms underlying their origins are still largely unknown in plants. Here, we investigated the origin of orphan genes in the Oryza sativa ssp. japonica “Nipponbare” genome using genome‐wide comparisons with 10 closely related Oryza species. We identified a total of 37 orphan genes in the Nipponbare genome that show short sequence lengths, elevated GC content, and absence of introns. Interestingly, half of the identified orphan genes originated by way of a distinctive mechanism that involved the generation of new coding sequences through independent and rapid divergence within the inserted transposable element. Our results provide valuable insight into genetic innovations in the model rice genome that formed on a very short timescale. 相似文献