首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   676篇
  免费   22篇
  国内免费   3篇
  2024年   1篇
  2023年   8篇
  2022年   22篇
  2021年   52篇
  2020年   19篇
  2019年   34篇
  2018年   39篇
  2017年   31篇
  2016年   26篇
  2015年   46篇
  2014年   54篇
  2013年   52篇
  2012年   54篇
  2011年   57篇
  2010年   27篇
  2009年   25篇
  2008年   27篇
  2007年   13篇
  2006年   21篇
  2005年   18篇
  2004年   11篇
  2003年   12篇
  2002年   8篇
  2001年   5篇
  2000年   1篇
  1999年   2篇
  1998年   2篇
  1995年   1篇
  1994年   4篇
  1991年   2篇
  1989年   1篇
  1988年   1篇
  1987年   1篇
  1986年   1篇
  1985年   3篇
  1984年   3篇
  1983年   2篇
  1982年   2篇
  1981年   2篇
  1980年   2篇
  1979年   2篇
  1977年   1篇
  1973年   1篇
  1972年   1篇
  1971年   1篇
  1970年   1篇
  1969年   2篇
排序方式: 共有701条查询结果,搜索用时 15 毫秒
601.
The destruction of β-cells of the pancreas leads to either insulin shortage or the complete absence of insulin, which in turn causes diabetes Mellitus. For treating diabetes, many trials have been conducted since the 19th century until now. In ancient times, insulin from an animal’s extract was taken to treat human beings. However, this resulted in some serious allergic reactions. Therefore, scientists and researchers have tried their best to find alternative ways for managing diabetes with progressive advancements in biotechnology. However, a lot of research trials have been conducted, and they discovered more progressed strategies and approaches to treat type I and II diabetes with satisfaction. Still, investigators are finding more appropriate ways to treat diabetes accurately. They formulated insulin analogs that mimic the naturally produced human insulin through recombinant DNA technology and devised many methods for appropriate delivery of insulin. This review will address the following questions: What is insulin preparation? How were these devised and what are the impacts (both positive and negative) of such insulin analogs against TIDM (type-I diabetes mellitus) and TIIDM (type-II diabetes mellitus)? This review article will also demonstrate approaches for the delivery of insulin analogs into the human body and some future directions for further improvement of insulin treatment.  相似文献   
602.
An efficient pathway was disclosed for the synthesis of 3-chloro-6-nitro-1H-indazole derivatives by 1,3-dipolar cycloaddition on dipolarophile compounds 2 and 3. Faced the problem of separation of two regioisomers, a click chemistry method has allowed us to obtain regioisomers of triazole-1,4 with good yields from 82 to 90% were employed. Also, the antileishmanial biological potency of the compounds was achieved using an MTT assay that reported compound 13 as a promising growth inhibitor of Leishmania major. Molecular docking demonstrated highly stable binding with the Leishmania trypanothione reductase enzyme and produced a network of hydrophobic and hydrophilic interactions. Molecular dynamics simulations were performed for TryR-13 complex to understand its structural and intermolecular affinity stability in a biological environment. The studied complex remained in good equilibrium with a structure deviation of ∼1–3 Å. MM/GBSA binding free energies illustrated the high stability of TryR-13 complex. The studied compounds are promising leads for structural optimisation to enhance the antileishmanial activity.  相似文献   
603.
Background: Defects in methylenetetrahydrofolate dehydrogenase 1-like (MTHFD1L) expression have earlier been examined in only a few human cancers. Objectives: Multi-omics profiling of MTHFD1L as a shared biomarker in distinct subtypes of human cancers. Methods: In the current study, for the multi-omics analysis of MTHFD1L in 24 major subtypes of human cancers, a comprehensive in silico approach was adopted to mine different open access online databases including UALCAN, Kaplan–Meier (KM) plotter, LOGpc, GEPIA, Human Protein Atlas (HPA), Gene Expression across Normal and Tumor tissue (GENT2), MEXPRESS, cBioportal, STRING, DAVID, TIMER, and Comparative Toxicogenomics Database (CTD). Results: We noticed that the expression of MTHFD1L was significantly higher in all the analyzed 24 subtypes of human cancers as compared with the normal controls. Moreover, MTHDF1L overexpression was also found to be significantly associated with the reduced overall survival (OS) duration of Bladder urothelial cancer (BLCA), Head and neck cancer (HNSC), Kidney renal papillary cell carcinoma (KIRP), Lung adenocarcinoma (LUAD), and Uterine corpus endometrial carcinoma (UCEC). This implies that MTHFD1L plays a significant role in the development and progression of these cancers. We further noticed that MTHFD1L was also overexpressed in BLCA, HNSC, KIRP, LUAD, and UCEC patients of different clinicopathological features. Pathways enrichment analysis revealed the involvement of MTHFD1L-associated genes in five diverse pathways. We also explored few interesting correlations between MTHFD1L expression and its promoter methylation, genetic alterations, CNVs, and between CD8+ T immune cells level. Conclusion: In conclusion, our results elucidated that MTHFD1L can serve as a shared diagnostic and prognostic biomarker in BLCA, HNSC, KIRP, LUAD, and UCEC patients of different clinicopathological features.  相似文献   
604.
The activity of polygalacturonase (PG, E.C 3.2.1.15) during ripening in climacteric fruits has been positively correlated with softening of the fruit tissue and differential expression of its gene is suspected to be regulated by the plant hormone ethylene. We have cloned four partial cDNAs, MAPG1 (acc. no. AF311881), MAPG2 (acc. no. AF311882), MAPG3 (acc. no. AF542382) and MAPG4 (acc. no. AY603341) for PG genes and studied their differential expression during ripening in banana. MAPG3 and MAPG4 are believed to be ripening related and regulated by ethylene whereas MAPG2 is associated more with senescence. MAPG1 shows constitutive expression and is not significantly expressed in fruit tissue. The genomic clone MAGPG (acc. No. AY603340) includes the complete MAPG3 gene, which consists of four exons and three introns. The structure of the gene has more similarity to tomato abscission PG rather than tomato fruit PG. It is concluded that softening during ripening in banana fruit results from the concerted action of at least four PG genes, which are differentially expressed during ripening.  相似文献   
605.
White clover plants were grown for 97 days under two temperature regimes (20/15°C and 8/5°C day/night temperatures) and were supplied with either small amounts (a total of 80 mg N pot–1) of ammonium (NH 4 + ) or nitrate (NO 3 ) nitrogen, or received no mineral N and relied on N2 fixation. Greatest growth and total leaf area of clover plants occurred in N2 fixing and NO 3 -fed plants grown at 20/15°C and poorest growth occurred in NH 4 + -fed plants grown at 8/5°C. Nodule mass per plant was greater at 8/5°C due to increased nodule numbers rather than increased dry weight per nodule. This compensated to some extent for the reduced N2-fixing activity per unit dry weight of nodule tissue found at the low growth temperature up to 116 d after sowing, but thereafter both activity per nodule dry weight and activity per plant were greater at the low temperature. Highest nitrate reductase activity (NRA) per g fresh weight and total activity per leaf, petiole or root occurred in NO 3 -fed plants at 8/5°C. Low growth temperature resulted in a greater partitioning of total plant NRA to the roots of NO 3 -fed plants. The results are considered in relation to the use of N fertiliser in the spring under field conditions.  相似文献   
606.
Gnetin, a new stilbene isolated from Gnetum ula is assigned the structure 3,4-methylenedioxy-4′-methoxy-trans-stilbene, 3 on the basis of spectroscopic data and synthesis. The structure 3,3′,4-trihydroxy-2-methoxy-trans-stilbene, 1a earlier assigned to a trihydroxymonomethoxy stilbene is now revised to 3,4,5′-trihydroxy-3′-methoxy-trans-stilbene, 1b.  相似文献   
607.
A technique is described for simple flow assessment of the in situ radial artery conduit during coronary bypass via a small incision. This technique allows morphologic and physiologic direct intraoperative assessment of radial artery quality and expands the use of radial artery during coronary artery surgery.  相似文献   
608.
Bioinformatics involves the collection, organization and analysis of large amounts of biological data, using networks of computers and databases. Developing countries in the Asia-Pacific region are just moving into this new field of information-based biotechnology. However, the computational infrastructure and network bandwidths available in these countries are still at a basic level compared to that in developed countries. In this study, we assessed the utility of a BitTorrent-based Peer-to-Peer (btP2P) file distribution model for automatic synchronization and distribution of large amounts of biological data among developing countries. The initial country-level nodes in the Asia-Pacific region comprised Thailand, Korea and Singapore. The results showed a significant improvement in download performance using btP2P--three times faster overall download performance than conventional File Transfer Protocol (FTP). This study demonstrated the reliability of btP2P in the dissemination of continuously growing multi-gigabyte biological databases across the three Asia-Pacific countries. The download performance for btP2P can be further improved by including more nodes from other countries into the network. This suggests that the btP2P technology is appropriate for automatic synchronization and distribution of biological databases and software over low-bandwidth networks among developing countries in the Asia-Pacific region. AVAILABILITY: http://everest.bic.nus.edu.sg/p2p/  相似文献   
609.
610.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号