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   4225篇
  免费   318篇
  2023年   38篇
  2022年   37篇
  2021年   139篇
  2020年   100篇
  2019年   139篇
  2018年   145篇
  2017年   113篇
  2016年   205篇
  2015年   258篇
  2014年   249篇
  2013年   281篇
  2012年   346篇
  2011年   329篇
  2010年   229篇
  2009年   193篇
  2008年   222篇
  2007年   189篇
  2006年   199篇
  2005年   148篇
  2004年   153篇
  2003年   124篇
  2002年   86篇
  2001年   52篇
  2000年   46篇
  1999年   31篇
  1998年   31篇
  1997年   19篇
  1996年   15篇
  1995年   18篇
  1994年   21篇
  1993年   18篇
  1992年   13篇
  1991年   25篇
  1990年   12篇
  1989年   19篇
  1988年   26篇
  1987年   22篇
  1986年   20篇
  1985年   28篇
  1984年   18篇
  1983年   17篇
  1982年   11篇
  1981年   15篇
  1980年   20篇
  1979年   9篇
  1978年   12篇
  1976年   9篇
  1973年   11篇
  1972年   8篇
  1970年   8篇
排序方式: 共有4543条查询结果,搜索用时 203 毫秒
81.
82.
83.
The ongoing coronavirus disease 2019 (COVID-19) crisis is having a large impact on acute and chronic cardiac care. Due to public health measures and t  相似文献   
84.
Purinergic Signalling - After more than two decades of preclinical and clinical studies, on August 27, 2019, the US Food and Drug Administration (FDA) approved the adenosine A2A receptor antagonist...  相似文献   
85.
86.

Lecythis pisonis Cambess, popularly known as sapucaia, has great economic and socio-environmental potential. The objective of this study was to evaluate the establishment and in vitro morphogenesis of L. pisonis under the effect of disinfecting agents, plant growth regulators, and thermal stress. The study was divided into three experiments: (i) development of the disinfection protocol by testing different concentrations and times of exposure to sodium hypochlorite (NaOCl) and different concentrations and methods of amoxicillin application, (ii) in vitro budding induction by testing different concentrations of 6-benzylaminopurine (BAP) or kinetin (KIN) supplemented to Woody Plant Medium (WPM) and Murashige and Skoog (MS) culture media, and (iii) in vitro formation from plantlets by analyzing different concentrations of indole-3-butyric acid (IBA) with different exposure times to a thermal stress of 40°C. The disinfection of stem segments was effective using 3% NaOCl and 3.0 g L−1 amoxicillin solution. MS culture medium supplemented with 0.25 mg L−1 BAP induced more shoots in vitro. One milligram per liter IBA promoted greater rooting in vitro, and it is not necessary for thermal stress tolerance.

  相似文献   
87.
We argue that the need for a quality seed supply chain is a major bottleneck for the restoration of Chile's native ecosystems, thus supplementing the list of bottlenecks proposed by Bannister et al. in 2018. Specifically, there is a need for defining seed transfer zones, developing standards and capacities for properly collecting and storing seeds, reducing information gaps on seed physiology and longevity, and implementing an efficient seed supply chain with certification of seed origin and quality. Without such capacities, countries are unlikely to meet their restoration commitments. Although we focus on bottlenecks in Chile, the issues we raise are relevant to other countries and thus the global agenda for ecological restoration.  相似文献   
88.

Seriola lalandi is an economically important species that is globally distributed in temperate and subtropical marine waters. Aquaculture production of this species has had problems associated with intensive fish farming, such as disease outbreaks or nutritional deficiencies causing high mortality. Intestinal microbiota are involved in many processes that benefit a host, such as disease control, stimulation of the immune response, and the promotion of nutrient metabolism. The aim of this study is to evaluate the in vitro probiotic properties of bacteria isolated from the intestinal content of wild Seriola lalandi. The probiotic potential was evaluated in terms of (i) the antimicrobial activity against vibrios causing outbreaks in farmed fish; (ii) the ability to stimulate genes related to an innate immune response in fish; and (iii) antibiotic resistance. Nineteen isolates identified as Pseudomonas, Shewanella, Psychrobacter, and Acinetobacter showed antimicrobial activity and significant relative expression of cytokines, serum amyloid A protein (SAA), hepcidin, and lysozyme. A positive correlation was observed between the levels of expression and the bacterial load after 24 h of exposure. Pseudomonas isolates showed a level of antibiotic resistance. In conclusion, isolates of the genera Shewanella, Psychrobacter, and Acinetobacter could serve as potential probiotics in S. lalandi culture.

  相似文献   
89.
90.
Lectins are a group of proteins of non‐immune origin recognized for their ability to bind reversibly to carbohydrates. Researchers have been intrigued by oligosaccharides and glycoconjugates for their involvement as mediators of complex cellular events and then many biotechnological applications of lectins are based on glycocode decoding and their activities. Here, we report a structural and biological study of a ConA‐like mannose/glucose‐specific lectin from Canavalia bonariensis seeds, CaBo. More specifically, we evaluate the binding of CaBo with α‐methyl‐D‐mannoside (MMA) and mannose‐1,3‐α‐D‐mannose (M13) and the resultant in vivo effects on a rat model of acute inflammation. A virtual screening was also carried out to cover a larger number of possible bindings of CaBo. In silico analysis demonstrated the stability of CaBo interaction with mannose‐type ligands, and the lectin was able to induce acute inflammation in rats with the participation of the carbohydrate recognition domain (CRD) and histamine release. These results confirm the ability of CaBo to interact with hybrid and high‐mannose N‐glycans, supporting the hypothesis that CaBo's biological activity occurs primarily through its interaction with cell surface glycosylated receptors.  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