全文获取类型
收费全文 | 398篇 |
免费 | 25篇 |
国内免费 | 43篇 |
专业分类
466篇 |
出版年
2024年 | 3篇 |
2022年 | 4篇 |
2021年 | 8篇 |
2020年 | 3篇 |
2019年 | 4篇 |
2018年 | 4篇 |
2017年 | 5篇 |
2016年 | 11篇 |
2015年 | 11篇 |
2014年 | 17篇 |
2013年 | 17篇 |
2012年 | 22篇 |
2011年 | 21篇 |
2010年 | 17篇 |
2009年 | 18篇 |
2008年 | 22篇 |
2007年 | 24篇 |
2006年 | 21篇 |
2005年 | 29篇 |
2004年 | 20篇 |
2003年 | 17篇 |
2002年 | 15篇 |
2001年 | 8篇 |
2000年 | 6篇 |
1999年 | 5篇 |
1998年 | 12篇 |
1997年 | 8篇 |
1996年 | 3篇 |
1995年 | 6篇 |
1994年 | 4篇 |
1993年 | 3篇 |
1992年 | 8篇 |
1991年 | 5篇 |
1990年 | 13篇 |
1989年 | 6篇 |
1988年 | 6篇 |
1986年 | 6篇 |
1985年 | 6篇 |
1984年 | 3篇 |
1983年 | 4篇 |
1982年 | 4篇 |
1978年 | 4篇 |
1976年 | 3篇 |
1975年 | 4篇 |
1973年 | 3篇 |
1971年 | 2篇 |
1970年 | 3篇 |
1968年 | 2篇 |
1957年 | 2篇 |
1955年 | 2篇 |
排序方式: 共有466条查询结果,搜索用时 46 毫秒
111.
圆瓣姜花根茎挥发油的化学成分 总被引:1,自引:0,他引:1
纳智 《热带亚热带植物学报》2006,14(5):417-420
利用水蒸汽蒸馏法提取圆瓣姜花根茎挥发油,运用毛细管气相色谱-质谱联用法对挥发油进行了分析,分离出60个峰,鉴定了其中的51种成分,所鉴定成分占挥发油总量的97.32%,其主要化学成分为单萜及倍半萜类化合物。 相似文献
112.
观察复方环丙酮胺喷剂治疗浅部真菌病的疗效。第Ⅰ批给予复方环丙酮胺喷剂,1次/d喷于患处,用药4周后观察疗效;第Ⅱ批随机入A、B组,A组给予复方环丙酮胺喷剂+曲安奈德喷剂,B组给予复方环丙酮胺喷剂,均1次/d喷于患处,用药2周、4周后观察疗效。第Ⅰ批治疗4周总有效率为80%;第Ⅱ批A、B组治疗2周总有效率分别为75%及82.35%,治疗4周总有效率分别为94.74%及100%。复方环丙酮胺喷剂和复方环丙酮胺喷剂+曲安奈德喷剂治疗浅部真菌病的疗效相似(P>0.05),且疗效显著、局部刺激小、瘙痒缓解明显、安全性较高。 相似文献
113.
AI Junkui ZHANG Zhiwen XIN Dianqi ZHU Hongjian YAN Quanjian XIN Zhongcheng NA Yanqun & GUO Yinglu . Institute of Urology Peking University & Department of Urology First Hospital Peking University Beijing China . Department of Physiology Peking University Health Science Center Beijing China . Department of Urology Xijing Hospital the th Military Medical University Xi抋n China 《中国科学:生命科学英文版》2004,47(2):148-157
Renal cell carcinoma (RCC) is a common uro- genital malignancy and often shows odd biological features. RCC accounts for approximately 2% of ma- lignancies worldwide. The incidence of and mortality from RCC have continuously increased during the last 50 years. One third of the patients already have me- tastases when first consulting the doctors. Another 30%—40% of patients develop metastasis after surgi- Identification of over-expressed genes in human RCC 149 cal excision of the pri… 相似文献
114.
Delaney Burnard Michelle J. Bauer Caitlin Falconer Ian Gassiep Robert E. Norton David L. Paterson Patrick NA Harris 《PLoS neglected tropical diseases》2022,16(6)
BackgroundBurkholderia pseudomallei is an environmental gram-negative bacterium that causes the disease melioidosis and is endemic in many countries of the Asia-Pacific region. In Australia, the mortality rate remains high at approximately 10%, despite curative antibiotic treatment being available. The bacterium is almost exclusively found in the endemic region, which spans the tropical Northern Territory and North Queensland, with clusters occasionally present in more temperate climates. Despite being endemic to North Queensland, these infections remain understudied compared to those of the Northern Territory.Methodology/Principal findingsThis study aimed to assess the prevalence of central nervous system (CNS) disease associated variant bimABm, identify circulating antimicrobial resistance mutations and genetically distinct strains from Queensland, via comparative genomics. From 76 clinical isolates, we identified the bimABm variant in 20 (26.3%) isolates and in 9 (45%) of the isolates with documented CNS infection (n = 18). Explorative analysis suggests a significant association between isolates carrying the bimABm variant and CNS disease (OR 2.8, 95% CI 1.3–6.0, P = 0.009) compared with isolates carrying the wildtype bimABp. Furthermore, 50% of isolates were identified as novel multi-locus sequence types, while the bimABm variant was more commonly identified in isolates with novel sequence types, compared to those with previously described. Additionally, mutations associated with acquired antimicrobial resistance were only identified in 14.5% of all genomes.Conclusions/SignificanceThe findings of this research have provided clinically relevant genomic data of B. pseudomallei in Queensland and suggest that the bimABm variant may enable risk stratification for the development CNS complications and be a potential therapeutic target. 相似文献
115.
Huibin Tang Ira J Smith Sabah NA Hussain Peter Goldberg Myung Lee Sista Sugiarto Guillermo L Godinez Baljit K Singh Donald G Payan Thomas A Rando Todd M Kinsella Joseph B Shrager 《Molecular medicine (Cambridge, Mass.)》2014,20(1):579-589
Mechanical ventilation (MV) is one of the lynchpins of modern intensive-care medicine and is life saving in many critically ill patients. Continuous ventilator support, however, results in ventilation-induced diaphragm dysfunction (VIDD) that likely prolongs patients’ need for MV and thereby leads to major associated complications and avoidable intensive care unit (ICU) deaths. Oxidative stress is a key pathogenic event in the development of VIDD, but its regulation remains largely undefined. We report here that the JAK–STAT pathway is activated in MV in the human diaphragm, as evidenced by significantly increased phosphorylation of JAK and STAT. Blockage of the JAK–STAT pathway by a JAK inhibitor in a rat MV model prevents diaphragm muscle contractile dysfunction (by ~85%, p < 0.01). We further demonstrate that activated STAT3 compromises mitochondrial function and induces oxidative stress in vivo, and, interestingly, that oxidative stress also activates JAK–STAT. Inhibition of JAK–STAT prevents oxidative stress-induced protein oxidation and polyubiquitination and recovers mitochondrial function in cultured muscle cells. Therefore, in ventilated diaphragm muscle, activation of JAK–STAT is critical in regulating oxidative stress and is thereby central to the downstream pathogenesis of clinical VIDD. These findings establish the molecular basis for the therapeutic promise of JAK–STAT inhibitors in ventilated ICU patients. 相似文献
116.
纳智 《植物资源与环境学报》2007,16(2):75-77
苦丁茶为中国南部及西南部的民间传统药用植物,经两千多年的应用和医学临床试验证明,苦丁茶具有清热解毒、抑菌消炎、抗衰老、降血脂、改善血液粘稠度和微循环、清除人体自由基及增强人体免疫能力等功效,被誉为保健茶、美容茶、降压茶和益寿茶[1,2]。苦丁茶来源较复杂,共有5科1 相似文献
117.
Jessamyn S. Markley David R. Carrier 《Comparative biochemistry and physiology. Part A, Molecular & integrative physiology》2010,155(2):146-153
The highly derived mechanism birds use to ventilate their lungs relies on dorsoventral excursions of their heavily muscled sternum and abdominal viscera. Our expectation of the level of mechanical work involved in this mechanism led us to hypothesize that the metabolic cost of breathing is higher in birds than in other tetrapods. To test this theory, we used unidirectional artificial ventilation (UDV) to stop normal ventilatory movements in guinea fowl (Numida meleagris L.) at rest and during treadmill locomotion at three speeds. Oxygen consumption was measured during normal breathing and UDV, and the difference was used to approximate the cost of ventilation. Contrary to our prediction, metabolism increased when ventilatory movements ceased during UDV at rest. Although we do not understand why this occurred we suspect that UDV induced a homeostatic mechanism to counteract the loss of carbon dioxide. Nevertheless, across all running speeds, metabolism decreased significantly with UDV, indicating a minimum cost of ventilation during running of 1.43 ± 0.62% of total running metabolism or 0.48 ± 0.21 mL O2 (L ventilated)? 1. These results suggest that the metabolic cost of ventilation is low in birds and that it is within the range of costs reported previously for other amniotes. 相似文献
118.
绵羊fertilin β基因编码区的钓取与结构分析 总被引:1,自引:0,他引:1
Fertilin β与精卵的结合和融合有密切关系。为探讨fertilin β蛋白在绵羊受精过程中的作用机理, 采用RACE技术, 首次钓取了该基因的编码区。结果绵羊fertilin β基因的编码区cDNA全长为2,217 bp。同源性分析显示, 绵羊的fertilin β氨基酸序列与牛、猪和人的fertilin β具有79.4%、66.7%和58.1%的同源性。系统发育分析表明, 绵羊fertilin β与牛属于同一分支, 并且也显示了绵羊和牛分类地位最近, 这和传统的分类一致。Fertilin β蛋白结构域分析显示, 绵羊fertilin β去整合素识别序列为TDE, 与牛的序列相同。除了上述三肽序列外, 紧随X-D/E-E的ECD保守序列, 从而形成了X-D/E-ECD五肽保守序列, 在绵羊fertilin β中该五肽序列为TDECE。 相似文献
119.
马铃薯糖转运蛋白基因的克隆及表达分析 总被引:1,自引:0,他引:1
植物SWEET基因家族是一类糖转运蛋白,在植物的生理活动和生长发育过程中发挥着重要功能。为了解马铃薯SWEET基因的相关信息,探究其在马铃薯不同组织以及在生物胁迫与非生物胁迫下的表达特性。该研究采用同源克隆技术从马铃薯‘青薯9号’中克隆了StSWEET5基因(GenBank登录号为MN295671),其CDS序列长度为717 bp,编码238个氨基酸。系统进化树分析结果表明,StSWEET5与番茄的氨基酸序列相似性最高(97.06%)。qRT-PCR分析表明:StSWEET5基因在马铃薯各组织(根、茎、叶、花、块茎、匍匐茎)中均有表达,且在花中的表达显著高于其他组织;糖胁迫下,StSWEET5基因在根、茎、叶中均有表达,尤其在根中的表达差异最为显著(P0.05)。在晚疫病菌(Phytophthora infestans)诱导后36 h时,表达量达到最高,随后急剧下调。推测StSWEET5基因参与了马铃薯糖胁迫以及响应了晚疫病诱导的过程。 相似文献
120.
Rosellinia desmazieresii was found for the first time on a tree of Scots pine. It occurred on a dying tree in a mixed Scots pine-oak plantation in Poland. The fungus girdled the base of the trunk, where perithecia were produced abundantly. The fungus was evidently the cause of the tree's poor growth and ultimate death. 相似文献