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   22745篇
  免费   1903篇
  国内免费   640篇
耳鼻咽喉   181篇
儿科学   133篇
妇产科学   221篇
基础医学   1186篇
口腔科学   240篇
临床医学   1347篇
内科学   2588篇
皮肤病学   171篇
神经病学   1590篇
特种医学   575篇
外科学   1028篇
综合类   4134篇
现状与发展   1篇
一般理论   4篇
预防医学   992篇
眼科学   432篇
药学   2114篇
  29篇
中国医学   7731篇
肿瘤学   591篇
  2024年   60篇
  2023年   548篇
  2022年   1380篇
  2021年   2047篇
  2020年   2048篇
  2019年   1910篇
  2018年   1661篇
  2017年   1476篇
  2016年   1258篇
  2015年   749篇
  2014年   1753篇
  2013年   2054篇
  2012年   2209篇
  2011年   1152篇
  2010年   894篇
  2009年   566篇
  2008年   489篇
  2007年   478篇
  2006年   384篇
  2005年   318篇
  2004年   264篇
  2003年   301篇
  2002年   203篇
  2001年   202篇
  2000年   131篇
  1999年   107篇
  1998年   94篇
  1997年   57篇
  1996年   53篇
  1995年   45篇
  1994年   52篇
  1993年   34篇
  1992年   19篇
  1991年   20篇
  1990年   19篇
  1989年   8篇
  1988年   4篇
  1986年   4篇
  1985年   48篇
  1984年   32篇
  1983年   29篇
  1982年   31篇
  1981年   19篇
  1980年   13篇
  1979年   13篇
  1978年   14篇
  1977年   11篇
  1976年   4篇
  1975年   7篇
  1973年   8篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
Barrett's esophagus (BE) is the precursor to esophageal adenocarcinoma (EAC). Progression to cancer typically occurs in a stepwise fashion through worsening dysplasia and ultimately, invasive neoplasia. Established EAC with deep involvement of the esophageal wall and/or metastatic disease is invariably associated with poor long-term survival rates. This guides the rationale of surveillance of Barrett’s in an attempt to treat lesions at an earlier, and potentially curative stage. The last two decades have seen a paradigm shift in management of Barrett’s with rapid expansion in the role of endoscopic eradication therapy (EET) for management of dysplastic and early neoplastic BE, and there have been substantial changes to international consensus guidelines for management of early BE based on evolving evidence. This review aims to assist the physician in the therapeutic decision-making process with patients by comprehensive review and summary of literature surrounding natural history of Barrett’s by histological stage, and the effectiveness of interventions in attenuating the risk posed by its natural history. Key findings were as follows. Non-dysplastic Barrett’s is associated with extremely low risk of progression, and interventions cannot be justified. The annual risk of cancer progression in low grade dysplasia is between 1%-3%; EET can be offered though evidence for its benefit remains confined to highly select settings. High-grade dysplasia progresses to cancer in 5%-10% per year; EET is similarly effective to and less morbid than surgery and should be routinely performed for this indication. Risk of nodal metastases in intramucosal cancer is 2%-4%, which is comparable to operative mortality rate, so EET is usually preferred. Submucosal cancer is associated with nodal metastases in 14%-41% hence surgery remains standard of care, except for select situations.  相似文献   
3.
Even if the relationships between nutrition and inflammatory bowel disease (IBD) remain underexplored, the current literature is providing, day by day, much more evidence on the effects of various diets in both prevention and treatment of such illnesses. Wrong dietary habits, together with other environmental factors such as pollution, breastfeeding, smoke, and/or antibiotics, are among the theoretical pathogenetic causes of IBD, whose multifactorial aetiology has been already confirmed. While some of these risk factors are potentially reversible, some others cannot be avoided, and efficient treatments become necessary to prevent IBD spread or recurrence. Furthermore, the drugs currently available for treatment of such disease provide low-to-no effect against the symptoms, making the illnesses still strongly disabling. Whether nutrition and specific diets will prove to effectively interrupt the course of IBD has still to be clarified and, in this sense, further research concerning the applications of such dietary interventions is still needed.  相似文献   
4.
5.
6.
目的 观察半夏泻心汤对饮用葡聚糖硫酸钠(DSS)诱导建立的溃疡性结肠炎(UC)模型小鼠Th17/Treg细胞平衡及肠道微生态的影响,从免疫失衡及菌群紊乱角度分析半夏泻心汤治疗UC的作用机制。方法 将40只C57BL/6J雄性小鼠随机分为空白组、模型组、阳性药(美沙拉嗪)组及半夏泻心汤组,除空白组外的各小鼠采用2.5% DSS水溶液自由饮用7天诱导建立UC小鼠模型。自实验第8日起,分别采用灭菌水、美沙拉嗪水溶液、半夏泻心汤水溶液给上述各组别小鼠灌胃。采用HE染色观察结肠组织病理学变化,ELISA方法检测组织炎症因子含量,流式细胞术检测Th17及Treg细胞的相对数量,16S rRNA测序技术进一步检测模型小鼠粪便中菌群的变化。结果 与空白组比较,模型组小鼠结肠损伤严重,血清炎症因子含量显著升高(P<0.01);与模型组比较,中药干预组小鼠结肠损伤减轻,血清TNF-α、IFN-γ含量显著下降(P<0.05)。较空白组小鼠相比,模型组小鼠Th17细胞百分比显著升高(P<0.01),而Treg细胞百分比显著降低(P<0.01)。经半夏泻心汤干预后,其小鼠Th17细胞数量均显著降低(P<0.05),Treg细胞数量则显著升高(P<0.05)。同时,半夏泻心汤可升高门水平上Firmicutes、属水平上Lachnospiraceae_NK4A136_group、unclassified_f_Lachnospiraceae、Prevotellaceae_UCG-001、Alistipes;降低门水平上Actinobacteriota,科水平上Bifidobacteriaceae、Atopobiaceae、Clostridiaceae,属水平上Clostridium_sensu_stricto_1、Coriobacteriaceae_UCG-002、Bifidobacterium的相对丰度。结论 半夏泻心汤可使Treg细胞相对数量升高、Th17细胞相对数量降低,以维持Th17/Treg细胞动态平衡;同时可降低有害菌Clostridium_sensu_stricto_1、Coriobacteriaceae_UCG-002的相对丰度,升高产短链脂肪酸类菌Lachnospiraceae_NK4A136_group、Prevotellaceae_UCG-001、unclassified_f_Lachnospiraceae等菌属的相对丰度,调控肠道微生物结构及动态平衡,从而发挥治疗UC的作用。  相似文献   
7.
Circadian rhythms are 24-hour natural rhythms regulated by the suprachiasmatic nucleus, also known as the "master clock". The retino-hypothalamic tract entrains suprachiasmatic nucleus with photic information to synchronise endogenous circadian rhythms with the Earth’s light-dark cycle. However, despite the robustness of circadian rhythms, an unhealthy lifestyle and chronic photic disturbances cause circadian rhythm disruption in the suprachiasmatic nucleus’s TTFL loops via affecting glutamate and γ-aminobutyric acid-mediated neurotransmission in the suprachiasmatic nucleus. Recently, considerable evidence has been shown correlating CRd with the incidence of Alzheimer's disease. The present review aims to identify the existence and signalling of endocannabinoids in CRd induced Alzheimer's disease through retino-hypothalamic tract- suprachiasmatic nucleus-cortex. Immunohistochemistry has confirmed the expression of cannabinoid receptor 1 in the suprachiasmatic nucleus to modulate the circadian phases of the master clock. Literature also suggests that cannabinoids may alter activity of suprachiasmatic nucleus by influencing the activity of their major neurotransmitter γ-aminobutyric acid or by interacting indirectly with the suprachiasmatic nucleus’s two other major inputs i.e., the geniculo-hypothalamic tract-mediated release of neuropeptide Y and serotonergic inputs from the dorsal raphe nuclei. Besides, the expression of cannabinoid receptor 2 ameliorates cognitive deficits via reduction of tauopathy and microglial activation. In conclusion, endocannabinoids may be identified as a putative target for correcting CRd and decelerating Alzheimer’s disease.  相似文献   
8.
BackgroundExplosion fatalities are the severest type of violent crimes. These involve the use of explosive devices in terrorist like activities in confined spaces in civilian or military settings, with mass number of people present all around. A stark dearth of literature for the forensic interpretation of such catastrophes is astonishing.PurposeCharacterization of the pattern of the multitude of injuries in explosions in confined spaces as guide for investigations and growth of literature on this entity.MethodologyA review of the archives of the forensic examinations of mass fatalities due to an explosion in a metro car was undertaken. It was combined with the reconstruction of the events by developing a three-dimensional model of this incident that involved seventeen fatalities.ResultsAll the decedents showed differential pattern of fatal injuries under the influence of damaging explosion factors (DEFs). The causative forces were characterized as gas-detonation (in all the cases), damaging effect by shock waves (59% of the cases), and impact of fragmentation and collision of the body (thrown off) with nearby objects. Traumatic effect due to shrapnel as well as blunt force was noted in 82% of the cases. Gross destruction of head due to combined effect of gas-detonation and fragmentation was seen in 29% of the cases.ConclusionAn interpretation of the nature and pattern of injuries in confined space explosions can help to estimate the location of deceased/s with respect to the epicenter and the type of DEFs.  相似文献   
9.
《Drug discovery today》2022,27(6):1733-1742
Compounds that exhibit assay interference or undesirable mechanisms of bioactivity are routinely encountered in assays at various stages of drug discovery. We observed that assays for the investigation of thiol-reactive and redox-active compounds have not been collected in a comprehensive review. Here, we review these assays and subject them to experimental optimization to improve their reliability. We demonstrate the usefulness of our assay cascade by assaying a library of bioactive compounds, chemical probes, and a set of approved drugs. These high-throughput assays should complement the array of wet-lab and in silico assays during the initial stages of hit discovery campaigns to pursue only hit compounds with tractable mechanisms of action.  相似文献   
10.
总结1例外阴Paget’s病术后创面感染的护理体会,利用伤口评估三角工具对患者创面进行评估,通过使用液体伤口敷料联合银离子敷料控制感染,富血小板血浆技术促进伤口愈合,个体化健康教育提高患者治疗依从性的整体干预方案对伤口进行有效管理,结果显示伤口愈合效果良好。  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