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   2000篇
  免费   272篇
  国内免费   1篇
  2024年   5篇
  2023年   21篇
  2022年   59篇
  2021年   111篇
  2020年   69篇
  2019年   78篇
  2018年   108篇
  2017年   92篇
  2016年   140篇
  2015年   159篇
  2014年   153篇
  2013年   186篇
  2012年   152篇
  2011年   137篇
  2010年   116篇
  2009年   71篇
  2008年   69篇
  2007年   73篇
  2006年   60篇
  2005年   58篇
  2004年   46篇
  2003年   32篇
  2002年   36篇
  2001年   22篇
  2000年   18篇
  1999年   21篇
  1997年   10篇
  1996年   6篇
  1995年   8篇
  1994年   4篇
  1993年   4篇
  1992年   5篇
  1991年   7篇
  1989年   5篇
  1988年   10篇
  1987年   9篇
  1986年   6篇
  1985年   8篇
  1984年   9篇
  1983年   10篇
  1982年   8篇
  1981年   5篇
  1980年   4篇
  1979年   3篇
  1977年   4篇
  1975年   4篇
  1974年   3篇
  1973年   4篇
  1971年   5篇
  1857年   4篇
排序方式: 共有2273条查询结果,搜索用时 62 毫秒
31.
32.
33.
Melanoma, as for many other cancers, undergoes a selection process during progression that limits many innate and adaptive tumor control mechanisms. Immunotherapy with immune checkpoint blockade overcomes one of the escape mechanisms but if the tumor is not eliminated other escape mechanisms evolve that require new approaches for tumor control. Some of the innate mechanisms that have evolved against infections with microorganisms and viruses are proving to be active against cancer cells but require better understanding of how they are activated and what inhibitory mechanisms may need to be targeted. This is particularly so for inflammasomes which have evolved against many different organisms and which recruit a number of cytotoxic mechanisms that remain poorly understood. Equally important is understanding of where these mechanisms will fit into existing treatment strategies and whether existing strategies already involve the innate killing mechanisms.  相似文献   
34.
Chitin is an organic polymer and it is the most frequent marine natural polysaccharide after cellulose. The main natural sources of chitin are exoskeletons of insects, mollusks, the cell walls of certain fungi and crustaceans such as crabs, shrimps and lobsters. The waste of these marine exoskeletons are pollutant for the environment, but these waste raw materials could be useful for production of commercial products like chitin. Chitin is an important raw material used for water treatment, agricultural, biomedical, biotechnological purposes, food and paper industry and cosmetics. Based on the variety of importance, the present targets of this study are to optimize the demineralization process for the removal of calcium and phosphate contents from the waste of Portunidae segnis (P. segnis) by using acid at ambient temperature and to characterize the isolated demineralized sample as well as the percentage of remaining calcium and phosphorus contents by using Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES). The prepared waste carbs coarse powder samples of P. segnis were demineralized with seven different concentrations of hydrochloric acid at ambient temperature for 1 h. All the demineralization samples by the different concentrations were analyzed by using sensitive ICP-OES. The results based on ICP-OES showed that among the seven different concentrations used in the demineralization process for the isolation of chitin, the best was 2 M of HCl concentration for the production of chitin. The results also showed that the optimized concentration 2 M HCl gave the minimum concentration of calcium and phosphorus compared to other concentrations applied in this experiment. In conclusion, the optimized concentration for demineralization process could be used commercially for the isolation or commercial production of chitin for agricultural, biomedical and biotechnological purposes.  相似文献   
35.
Molecular Biology Reports - Alzheimer’s disease (AD) is a neurodegenerative old age disease that is complex, multifactorial, unalterable, and progressive in nature. The currently approved...  相似文献   
36.
37.
International Journal of Biometeorology - Epidemiological studies have suggested an association between particulate air pollution, increased temperatures, and morbidity related to pregnancy...  相似文献   
38.
The axolotl, Ambystoma mexicanum, is used extensively for research in developmental biology, particularly for its ability to regenerate and restore lost organs, including in the nervous system, to full functionality. Regeneration in mammals typically depends on the healing process and scar formation with limited replacement of lost tissue. Other organisms, such as spiny mice (Acomys cahirinus), salamanders, and zebrafish, are able to regenerate some damaged body components. Blastema is a tissue that is formed after tissue injury in such organisms and is composed of progenitor cells or dedifferentiated cells that differentiate into various cell types during regeneration. Thus, identifying the molecules responsible for initiation of blastema formation is an important aspect for understanding regeneration. Introns, a major source of noncoding RNAs (ncRNAs), have characteristic sizes in the axolotl, particularly in genes associated with development. These ncRNAs, particularly microRNAs (miRNAs), exhibit dynamic regulation during regeneration. These miRNAs play an essential role in timing and control of gene expression to order and organize processes necessary for blastema creation. Master keys or molecules that underlie the remarkable regenerative abilities of the axolotl remain to be fully explored and exploited. Further and ongoing research on regeneration promises new knowledge that may allow improved repair and renewal of human tissues.  相似文献   
39.
40.
Cell and Tissue Banking - The detection of corneas operated on for refractive surgery [LASIK or photorefractive keratectomy (PRK)] will become a major concern for eye banks in the coming years...  相似文献   
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