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   5904篇
  免费   319篇
  国内免费   9篇
  2023年   86篇
  2022年   73篇
  2021年   304篇
  2020年   148篇
  2019年   168篇
  2018年   184篇
  2017年   156篇
  2016年   275篇
  2015年   300篇
  2014年   318篇
  2013年   469篇
  2012年   436篇
  2011年   471篇
  2010年   268篇
  2009年   244篇
  2008年   329篇
  2007年   296篇
  2006年   266篇
  2005年   220篇
  2004年   204篇
  2003年   173篇
  2002年   176篇
  2001年   48篇
  2000年   44篇
  1999年   40篇
  1998年   31篇
  1997年   34篇
  1996年   15篇
  1995年   27篇
  1994年   28篇
  1993年   24篇
  1992年   18篇
  1991年   17篇
  1990年   15篇
  1989年   20篇
  1988年   17篇
  1987年   18篇
  1985年   25篇
  1984年   22篇
  1983年   18篇
  1982年   26篇
  1981年   14篇
  1980年   17篇
  1979年   9篇
  1978年   16篇
  1977年   13篇
  1974年   7篇
  1970年   12篇
  1968年   8篇
  1966年   9篇
排序方式: 共有6232条查询结果,搜索用时 31 毫秒
71.
72.
73.
The current study investigated the effect of developmental stages on the chemical composition and the antioxidant activity of fifteen crude oil samples obtained from Pistacia atlantica Desf. leaves, galls, and fruits. Twelve fatty acids were detected by GC/FID, linolenic acid (C18 : 3) was the major fatty acid detected in leaves crude oils that registered [41.73 % (P<0.05)] on the last stage. The best content of tocopherols and carotenoids was recorded at the last stage for leaves and galls oils, respectively, with values of [1.530±0.01, 0.52±0.01 (P<0.05) mg α‐tocopherol equivalent/g DW] and [86.60±0.95, 69.15±0.13 (P<0.05) μg β‐carotene equivalent/g DW]. For fruits oils, the content varied depending on the levels of fruits maturation. The results from DPPH, FRAP, and ABTS assays revealed that the antioxidant activity increased with the increasing content of tocopherols and carotenoids in leaves and galls oils during development stages, and varied for fruits oils depending on the ripening stages. Moreover, according to PCA analysis, the best phytoconstituent content and antioxidant activity were attributed to P. atlantica Desf. fruit's crude oils. Also, a strong relationship was found between the antioxidant activity and bioactive phytochemical components, such as tocopherols, carotenoids, and omega‐three fatty acid, which confirmed that P. atlantica Desf. crude oils present a valuable source of natural antioxidant that could be used for pharmaceutical and food industries purposes.  相似文献   
74.
Virologica Sinica - Hepatitis C virus (HCV) is still one of the main causes of liver disease worldwide. Metabolic disorders, including non-alcoholic fatty liver disease (NAFLD), induced by HCV have...  相似文献   
75.
76.
For eukaryotes like fungi to regulate biological responses to environmental stimuli, various signalling cascades are utilized, like the highly conserved mitogen‐activated protein kinase (MAPK) pathways. In the model fungus Aspergillus nidulans, a MAPK pathway known as the pheromone module regulates development and the production of secondary metabolites (SMs). This pathway consists five proteins, the three kinases SteC, MkkB and MpkB, the adaptor SteD and the scaffold HamE. In this study, homologs of these five pheromone module proteins have been identified in the plant and human pathogenic fungus Aspergillus flavus. We have shown that a tetrameric complex consisting of the three kinases and the SteD adaptor is assembled in this species. It was observed that this complex assembles in the cytoplasm and that MpkB translocates into the nucleus. Deletion of steC, mkkB, mpkB or steD results in abolishment of both asexual sporulation and sclerotia production. This complex is required for the positive regulation of aflatoxin production and negative regulation of various SMs, including leporin B and cyclopiazonic acid (CPA), likely via MpkB interactions in the nucleus. These data highlight the conservation of the pheromone module in Aspergillus species, signifying the importance of this pathway in regulating fungal development and secondary metabolism.  相似文献   
77.
The current study characterizes and analyzes glow curves obtained from phosphate glass doped with different concentrations of lanthanum. Kinetic parameters of the glow curves obtained from beta‐irradiated phosphate glass samples doped with lanthanum were determined using a newly designed deconvoluted software. The obtained results from the analyses indicated that the glow curves of the phosphate glass samples were composed of five overlapping peaks. The activation energies of the five electron traps were located between 0.622 and 1.133 eV. The obtained kinetic parameters were evaluated using the designed software and another two methods and all revealed good agreement. The first three traps displayed non‐first‐order behaviour, while the two deep traps obeyed nearly first‐order kinetics.  相似文献   
78.
79.
Acetaminophen (APAP) overdose leads to liver injury. NLRP3 inflammasome is a key player in APAP‐induced inflammation. Also, apoptosis and liver regeneration play an important role in liver injury. Therefore, we assessed allicin's protective effect on APAP‐induced hepatotoxicity and studied its effect on NLRP3 inflammasome and apoptosis. Mice in the APAP group were injected by APAP (250 mg/kg, intraperitoneal). The allicin‐treated group received allicin orally (10 mg/kg/d) during 7 days before APAP injection. Serum and hepatic tissues were separated 24 hours after APAP injection. Serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), albumin, alkaline phosphatase (ALP), and hepatic malondialdehyde (MDA) were assessed using the colorimetric method. Hepatic NLRP3 inflammasome, caspase‐1, and interleukin‐1β (IL‐1β) were estimated using enzyme‐linked immunosorbent assay. Hepatic Bcl‐2 and Ki‐67 were investigated by immunohistochemistry. APAP significantly increased AST, ALT, and ALP, whereas allicin significantly decreased their levels. Also, APAP significantly decreased albumin and allicin significantly improved it. APAP produced changes in liver morphology, including inflammation and massive coagulative necrosis. Allicin protected the liver from APAP‐induced necrosis, apoptosis, and hepatocellular degeneration via increasing Bcl‐2 and Ki‐67 levels. APAP significantly increased the hepatic MDA, whereas allicin significantly prevented this increase. APAP markedly activated the NLRP3 inflammasome pathway and consequently increased the production of caspase‐1 and IL‐1β. Interestingly, we found that allicin significantly inhibited NLRP3 inflammasome activation, which resulted in decreased caspase‐1 and IL‐1β levels. Allicin has a hepatoprotective effect against APAP‐induced liver injury via the decline of oxidative stress and inhibition of the inflammasome pathway and apoptosis. Therefore, allicin might be a novel tool to halt the progression of APAP‐stimulated hepatotoxicity.  相似文献   
80.
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