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   538479篇
  免费   40003篇
  国内免费   21393篇
耳鼻咽喉   6173篇
儿科学   15066篇
妇产科学   6367篇
基础医学   65644篇
口腔科学   13179篇
临床医学   55218篇
内科学   75401篇
皮肤病学   8375篇
神经病学   34961篇
特种医学   23803篇
外国民族医学   158篇
外科学   79635篇
综合类   71331篇
现状与发展   77篇
一般理论   1篇
预防医学   24918篇
眼科学   9332篇
药学   47877篇
  168篇
中国医学   18182篇
肿瘤学   44009篇
  2024年   771篇
  2023年   6077篇
  2022年   9944篇
  2021年   21096篇
  2020年   15523篇
  2019年   19870篇
  2018年   15399篇
  2017年   15432篇
  2016年   18116篇
  2015年   21811篇
  2014年   36534篇
  2013年   36832篇
  2012年   36374篇
  2011年   35762篇
  2010年   31385篇
  2009年   30481篇
  2008年   29566篇
  2007年   29776篇
  2006年   26558篇
  2005年   21677篇
  2004年   16274篇
  2003年   14317篇
  2002年   11678篇
  2001年   10046篇
  2000年   8680篇
  1999年   7124篇
  1998年   6870篇
  1997年   6385篇
  1996年   5517篇
  1995年   5064篇
  1994年   4577篇
  1993年   3729篇
  1992年   3555篇
  1991年   3166篇
  1990年   2851篇
  1989年   2671篇
  1988年   2445篇
  1987年   2101篇
  1986年   1893篇
  1985年   3121篇
  1984年   3010篇
  1983年   2151篇
  1982年   2330篇
  1981年   2175篇
  1980年   1891篇
  1979年   1567篇
  1978年   1200篇
  1977年   1120篇
  1976年   929篇
  1973年   590篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
41.
Oxidative stress and inflammation are two possible mechanisms related to nephrotoxicity caused by environmental pollutants. Ellagic acid, a powerful antioxidant phytochemical, may have great relevance in mitigating pollutant-induced nephrotoxicity and preventing the progression of kidney disease. This review discusses the latest findings on the protective effects of ellagic acid, its metabolic derivatives, the urolithins, against kidney toxicity caused by heavy metals, pesticides, mycotoxins, and organic air pollutants. We describe the chelating, antioxidant, anti-inflammatory, antifibrotic, antiautophagic, and antiapoptotic properties of ellagic acid to attenuate nephrotoxicity. Furthermore, we present the molecular targets and signaling pathways that are regulated by these antioxidants, and suggest some others that should be explored. Nevertheless, the number of reports is still limited to establish the efficacy of ellagic acid against kidney damage induced by environmental pollutants. Therefore, additional preclinical studies on this topic are required, as well as the development of well-designed clinical trials.  相似文献   
42.

Background

Hyperglycaemia is common in patients with acute brain injury admitted to an intensive care unit (ICU). Many studies have found associations between development of hyperglycaemia and increased mortality in hospitalised patients. However, the optimal target for blood glucose control is unknown. We want to conduct a systematic review with meta-analysis and trial sequential analysis to explore the beneficial and harmful effects of restrictive versus liberal glucose control on patient outcomes in adults with severe acute brain injury.

Methods

We will systematically search medical databases including CENTRAL, Embase, MEDLINE and trial registries. We will search the following websites for ongoing or unpublished trials: http://www.controlled-trials.com/ , http://www.clinicaltrials.gov/ , www.eudraCT.com , http://centerwatch.com/ , The Cochrane Library's CENTRAL, PubMed, EMBASE, Science Citation Index Expanded and CINAHL. Two authors will independently review and select trials and extract data. We will include randomised trials comparing levels of glucose control in our analyses and observational studies will be included to address potential harms. The primary outcomes are defined as all-cause mortality, functional outcome and health-related quality of life. Secondary outcomes include serious adverse events including hypoglycaemia, length of ICU stay and duration of mechanical ventilation, and explorative outcomes including intracranial pressure and infection. Trial Sequential Analysis will be used to investigate the risk of type I error due to repetitive testing and to further explore imprecision. Quality of trials will be evaluated using the Cochrane Risk of Bias tool, and quality of evidence will be assessed using the Grading of Recommendations, Assessment, Development and Evaluations (GRADE) approach.

Discussion

The results of the systematic review will be disseminated through peer-reviewed publication. With the review, we hope to inform future randomised clinical trials and improve clinical practice.  相似文献   
43.
44.
目的 探讨溶质载体蛋白(SLC)及其受体趋化因子受体7(CCR7)与I期非小细胞肺癌(NSCLC)淋巴结微转移的相关性。方法 选取2019年1月~2020年3月于我院就诊的I期NSCLC患者127例为研究对象,按照淋巴结微转移情况分为对照组92例和转移组35例,所有患者入院后均通过根治术切除病灶,通过免疫组化方式检测病灶中SLC7A11及CCR7含量,并收集患者临床资料、实验室检查资料及影像学检查资料。通过Logistic回归分析评价SLC7A11及CCR7与淋巴结微转移之间的关系。最后通过建立ROC曲线分析两者及其联合检测对NSCLC患者微淋巴结转移的预测价值。结果 两组患者SLC7A11及CCR7表达水平存在显著差异(P<0.05)。转移组患者病灶直径、支气管受累及TLG显著高于对照组(P<0.05)。病灶直径(OR=49.254,95%CI=11.062~507.604)是影响NSCLC淋巴结微转移的独立危险因素(P<0.05)。SLC7A11(OR=8.622)及CCR7(OR=8.709)表达水平是影响NSCLC淋巴结微转移的独立因素(P<0.05)。SLC7A11、CCR7及联合诊断对NSCLC淋巴结微转移具有较好的检测价值(均P<0.05)。联合检测特异度显著高于 SLC7A11及CCR7单独检测(2=7.292,15.125;均P<0.01)。结论 SLC家族的中SLC7A11及其受体CCR7与NSCLC患者微淋巴结转移显著相关。  相似文献   
45.
孙悦  刘馨甜  张弘 《安徽医药》2022,26(11):2126-2130
角膜移植为治疗角膜盲的主要手段,而角膜移植排斥则是决定角膜植片存活时间和病人术后视力的关键。角膜得益于其特殊的眼前节“免疫赦免”状态,使得角膜移植能够在众多器官移植中享有极低的排斥率,然而排斥反应发生的风险依然存在。当机体处于遗传物质异常的特殊状态时,宿主将通过宏观调控“免疫赦免”状态对植片的保护作用或受体对移植物排异产生的有害作用,延迟或促进角膜移植排斥反应的发生,进而影响移植物的存活时间和透明度。该文综述与角膜移植排斥相关的多种全身性遗传疾病,总结全身性遗传疾病对角膜移植排斥的影响,浅析其发生的病理生理学机制以及诊疗的特殊性。  相似文献   
46.
In this paper, we argue that understanding and addressing the problem of poor-quality medical products requires a more interdisciplinary approach than has been evident to date. While prospective studies based on rigorous standardized methodologies are the gold standard for measuring the prevalence of poor-quality medical products and understanding their distribution nationally and internationally, they should be complemented by social science research to unpack the complex set of social, economic, and governance factors that underlie these patterns. In the following sections, we discuss specific examples of prospective quality surveys and of social science studies, highlighting the value of cross-sector partnerships in driving high-quality, policy-relevant research in this area.  相似文献   
47.
48.
《Survey of ophthalmology》2023,68(5):940-956
Congenital aniridia is a panocular disorder that is typically characterized by iris hypoplasia and aniridia-associated keratopathy (AAK). AAK results in the progressive loss of corneal transparency and thereby loss of vision. Currently, there is no approved therapy to delay or prevent its progression, and clinical management is challenging because of phenotypic variability and high risk of complications after interventions; however, new insights into the molecular pathogenesis of AAK may help improve its management. Here, we review the current understanding about the pathogenesis and management of AAK. We highlight the biological mechanisms involved in AAK development with the aim to develop future treatment options, including surgical, pharmacological, cell therapies, and gene therapies.  相似文献   
49.
Major depressive disorder is a serious and common neuropsychiatric disorder that affects more than 350 million people worldwide. Electroconvulsive therapy is the oldest and most effective treatment available for the treatment of severe major depressive disorder. Electroconvulsive therapy modifies structural network changes in patients with major depressive disorder and schizophrenia. And it can also affect neuroinflammatory responses and may have neuroprotective effects. Electroconvulsive therapy plays an irreplaceable role in the treatment of major depressive disorder.  相似文献   
50.
《Vaccine》2022,40(7):1001-1009
Vaccination guidelines for dogs and cats indicate that core vaccines (for dogs, rabies, distemper, adenovirus, parvovirus; for cats, feline parvovirus, herpes virus-1, calicivirus) are essential to maintain health, and that non-core vaccines be administered according to a clinician’s assessment of a pet’s risk of exposure and susceptibility to infection. A reliance on individual risk assessment introduces the potential for between-practice inconsistencies in non-core vaccine recommendations. A study was initiated to determine non-core vaccination rates of dogs (Leptospira, Borrelia burgdorferi, Bordetella bronchiseptica, canine influenza virus) and cats (feline leukemia virus) in patients current for core vaccines in veterinary practices across the United States. Transactional data for 5,531,866 dogs (1,670 practices) and 1,914,373 cats (1,661 practices) were retrieved from practice management systems for the period November 1, 2016 through January 1, 2020, deidentified and normalized. Non-core vaccination status was evaluated in 2,798,875 dogs and 788,772 cats that were core-vaccine current. Nationally, median clinic vaccination rates for dogs were highest for leptospirosis (70.5%) and B. bronchiseptica (68.7%), and much lower for canine influenza (4.8%). In Lyme-endemic states, the median clinic borreliosis vaccination rate was 51.8%. Feline leukemia median clinic vaccination rates were low for adult cats (34.6%) and for kittens and 1-year old cats (36.8%). Individual clinic vaccination rates ranged from 0 to 100% for leptospirosis, B. bronchiseptica and feline leukemia, 0–96% for canine influenza, and 0–94% for borreliosis. Wide variation in non-core vaccination rates between clinics in similar geographies indicates that factors other than disease risk are driving the use of non-core vaccines in pet dogs and cats, highlighting a need for veterinary practices to address gaps in patient protection. Failure to implement effective non-core vaccination strategies leaves susceptible dogs and cats unprotected against vaccine-preventable diseases.  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