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   4721篇
  免费   317篇
  国内免费   301篇
  5339篇
  2024年   6篇
  2023年   68篇
  2022年   160篇
  2021年   240篇
  2020年   153篇
  2019年   184篇
  2018年   187篇
  2017年   140篇
  2016年   202篇
  2015年   262篇
  2014年   340篇
  2013年   371篇
  2012年   411篇
  2011年   348篇
  2010年   228篇
  2009年   212篇
  2008年   232篇
  2007年   166篇
  2006年   161篇
  2005年   159篇
  2004年   155篇
  2003年   146篇
  2002年   104篇
  2001年   118篇
  2000年   83篇
  1999年   95篇
  1998年   46篇
  1997年   34篇
  1996年   37篇
  1995年   34篇
  1994年   30篇
  1993年   18篇
  1992年   29篇
  1991年   22篇
  1990年   33篇
  1989年   8篇
  1988年   17篇
  1987年   12篇
  1986年   10篇
  1985年   8篇
  1984年   10篇
  1983年   9篇
  1982年   8篇
  1981年   5篇
  1980年   6篇
  1979年   3篇
  1978年   3篇
  1977年   3篇
  1975年   6篇
  1974年   3篇
排序方式: 共有5339条查询结果,搜索用时 0 毫秒
91.
Molluscicidal activity of B-2 (sodium 2,5-dichloro-4-bromophenol; called as Phebrol and registered in WHO as OMS 3012) was evaluated in a laboratory and the field trials were performed in two different localities in Yueyang city, China, for control of Oncomelania hupensis. B-2 was effective against O. hupensis both in the laboratory and in the field. A dosage of 50 g/m2 in 10% granular form or 20 ml/m2 in 25% liquid form of B-2 would be recommendable as a standard mollusciciding dose for control of O. hupensis.  相似文献   
92.
93.
Cancer stem cells (CSCs) are a source of tumour recurrence in patients with nasopharyngeal carcinoma (NPC); however, the function of microRNA‐124 (miR‐124) in NPC CSCs has not been clearly defined. In this study, we investigated the role of miR‐124 in NPC CSCs. qRT‐PCR was performed to measure miR‐124 expression in NPC tissues and cell lines and the effects of miR‐124 on stem‐like properties and radiosensitivity of NPC cells measured. Luciferase reporter assays and rescue experiments were used to investigate the interaction of miR‐124 with the 3′UTR of junctional adhesion molecule A (JAMA). Finally, we examined the effects of miR‐124 in an animal model and clinical samples. Down‐regulation of miR‐124 was detected in cancer tissues and was inversely associated with tumour stage and lymph node metastasis. Overexpression of miR‐124 inhibited stemness properties and enhanced radiosensitivity of NPC cells in vitro and in vivo via targeting JAMA. Up‐regulation of miR‐124 was correlated with superior overall survival of patients with NPC. Our study demonstrates that miR‐124 can inhibit stem‐like properties and enhance radiosensitivity by directly targeting JAMA in NPC. These findings provide novel insights into the molecular mechanisms underlying therapy failure in NPC.  相似文献   
94.
95.
Rechargeable aqueous Zn/MnO2 batteries are very attractive large‐scale energy storage technologies, but still suffer from limited cycle life and low capacity. Here the novel adoption of a near‐neutral acetate‐based electrolyte (pH ≈ 6) is presented to promote the two‐electron Mn4+/Mn2+ redox reaction and simultaneously enable a stable Zn anode. The acetate anion triggers a highly reversible MnO2/Mn2+ reaction, which ensures high capacity and avoids the issue of structural collapse of MnO2. Meanwhile, the anode‐friendly electrolyte enables a dendrite‐free Zn anode with outstanding stability and high plating/stripping Coulombic efficiency (99.8%). Hence, a high capacity of 556 mA h g?1, a lifetime of 4000 cycles without decay, and excellent rate capability up to 70 mA cm?2 are demonstated in this new near‐neutral aqueous Zn/MnO2 battery by simply manipulating the salt anion in the electrolyte. The acetate anion not only modifies the surface properties of MnO2 cathode but also creates a highly compatible environment for the Zn anode. This work provides a new opportunity for developing high‐performance Zn/MnO2 and other aqueous batteries based on the salt anion chemistry.  相似文献   
96.
Mao  Yingyan  Yang  Diya  Li  Jing  Liu  Jun  Hou  Ruowu  Zhang  Zheng  Yang  Yiquan  Tian  Lei  Weinreb  Robert N.  Wang  Ningli 《中国科学:生命科学英文版》2020,63(12):1887-1894
Science China Life Sciences - The present study aims to assess the potential difference of biomechanical response of the optic nerve head to the same level of trans-lamina cribrosa pressure...  相似文献   
97.
Despite their important roles in host nutrition and metabolism, and potential to cause disease, our knowledge of the fungal community in the mammalian gut is quite limited. To date, diversity and composition of fungi in swine gut still remains unknown. Therefore, the first internal transcribed spacer of fungi in faecal samples from three breeds of pigs (10 pigs for each breed) was sequenced based on an Illumina HiSeq 2500 platform, and the relationship between the fungal community and the concentrations of main short-chain fatty acids (SCFAs) was also analysed. Results indicated that Chenghua (local, higher body fat rate), Yorkshire (foreign, higher lean meat and growth rate) and Tibetan (plateau, stronger disease resistance) pigs harboured distinct fungal community. The Basidiomycota and Ascomycota presented as the two predominant phyla, with Loreleia, Russula and Candida as the top three genera in all samples. Network analysis revealed a total of 35 correlations among different fungal genera, with 27 (77.14%) positive and 8 (22.86%) negative pairwise interactions. Canonical correspondence analysis suggested that fungi in the faeces of pigs were more correlated to the concentration of acetate and butyrate rather than propionate. Spearman’s correlation further showed that Tomentella was positively correlated to both acetate and butyrate, and Loreleia was positively correlated to propionate (P < 0.05), while Nephroma and Taiwanofungus were negatively correlated to acetate and propionate (P < 0.05). These findings expanded our knowledge on the intestinal fungi in pigs with different genotypes and phenotypes, indicating that fungi may play an indispensable role during the metabolism of host and the maintenance of intestinal health. The cross-feeding between fungi and other microorganisms may be crucial during the digestion of dietary carbohydrates and the associated physiological processes, which is worthy to be further studied.  相似文献   
98.
99.
100.
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