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   27008篇
  免费   1648篇
  国内免费   338篇
耳鼻咽喉   24篇
儿科学   574篇
妇产科学   6955篇
基础医学   2974篇
口腔科学   185篇
临床医学   2848篇
内科学   1926篇
皮肤病学   243篇
神经病学   490篇
特种医学   323篇
外国民族医学   2篇
外科学   1025篇
综合类   4641篇
一般理论   4篇
预防医学   3754篇
眼科学   67篇
药学   2213篇
  42篇
中国医学   455篇
肿瘤学   249篇
  2024年   15篇
  2023年   359篇
  2022年   452篇
  2021年   969篇
  2020年   997篇
  2019年   962篇
  2018年   854篇
  2017年   1072篇
  2016年   1190篇
  2015年   1001篇
  2014年   1773篇
  2013年   2587篇
  2012年   1495篇
  2011年   1800篇
  2010年   1448篇
  2009年   1249篇
  2008年   1227篇
  2007年   1183篇
  2006年   1199篇
  2005年   973篇
  2004年   906篇
  2003年   726篇
  2002年   542篇
  2001年   501篇
  2000年   408篇
  1999年   375篇
  1998年   250篇
  1997年   236篇
  1996年   233篇
  1995年   278篇
  1994年   192篇
  1993年   170篇
  1992年   134篇
  1991年   127篇
  1990年   120篇
  1989年   107篇
  1988年   110篇
  1987年   71篇
  1986年   68篇
  1985年   125篇
  1984年   93篇
  1983年   78篇
  1982年   72篇
  1981年   45篇
  1980年   59篇
  1979年   45篇
  1978年   31篇
  1977年   22篇
  1976年   21篇
  1973年   12篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
目的 建立妊娠11~13+6周子宫动脉多普勒参数在低危人群中的正常参考值,同时评估其对不良妊娠结局的预测价值。方法 收集2019年6月至2021年6月于我院行产前超声检查的妊娠11~13+6周孕妇,根据妊娠结局分组。收集两侧子宫动脉多普勒指标,包括搏动指数(PI)、阻力指数(RI)、舒张早期是否有切迹,以及孕妇基本临床资料和胎儿出生信息,将以上相关参数进行统计学分析。结果 最终纳入800例孕妇,包括正常妊娠结局组740例和不良妊娠结局组60例。两组孕妇体质量指数(BMI)、分娩孕周和胎儿出生体质量比较,差异均有统计学意义(均P<0.05)。随着孕周的增加,子宫动脉两侧平均搏动指数(mPI)、平均阻力指数(mRI)和两侧舒张早期切迹检出率均呈逐渐下降的趋势。ROC曲线分析显示,mPI、mRI及两侧舒张早期切迹预测妊娠结局的曲线下面积(AUC)分别为0.542、0.574、0.521,三者联合预测妊娠结局的AUC为0.648;孕妇BMI、年龄mPI、mRI及两侧舒张早期切迹预测妊娠结局的AUC为0.751。结论 建立了低危人群在妊娠11~13+6周子宫动脉多普勒参数的正常参考值范围。在妊娠11~13+6周单纯应用子宫动脉多普勒参数预测妊娠结局的价值有限,将子宫动脉参数与临床相关指标结合可提高对不良妊娠结局的预测价值。  相似文献   
2.
ObjectiveTo examine the characteristics and effectiveness of lifestyle interventions for gestational diabetes mellitus (GDM) in pregnancy and the postpartum period to prevent Type 2 diabetes.Data SourcesWe conducted searches in seven databases, including Ovid MEDLINE, CINAHL, Ovid Embase, Cochrane Central, Web of Science, Ovid PsycInfo, and ProQuest Dissertations and Theses for articles published from inception to January 2021.Study SelectionWe included articles on controlled intervention studies in which researchers evaluated a lifestyle intervention provided during pregnancy and the postpartum period for women with or at risk for GDM that were published in English.Data ExtractionTwelve articles that were reports of seven studies met the inclusion criteria. In some cases, more than one article was selected from the same study. For example, articles reported different outcomes from the same study. We extracted data with the use of a data collection form and compared and synthesized data on study design, purpose, sample, intervention characteristics, recruitment and retention, and outcomes.Data SynthesisAll seven studies focused on weight management and/or healthy lifestyle behaviors (diet and physical activity). Outcomes included glucose regulation, weight, lifestyle behaviors, and knowledge. The interventions varied in duration/dosage, strategies, and modes of delivery. In four studies, researchers reported interventions that had significant effects on improving glucose regulation and/or weight change. Some characteristics from the four effective interventions included goal setting, individualized care, and good retention rates. In the other three studies, limitations included low rates of participant retention, lack of personalized interventions, and limited population diversity or lack of culturally sensitive care.ConclusionLifestyle interventions provided during and after pregnancy to reduce the risk associated with GDM have the potential to improve outcomes. Health care counseling to promote healthy lifestyle behaviors related to the prevention of Type 2 diabetes is needed at different stages of maternity care for women with GDM. Additional high-quality studies are needed to address the limitations of current studies.  相似文献   
3.
Since the start of the COVID-19 pandemic, few studies have reported anaesthetic outcomes in parturients with SARS-CoV-2 infection. We reviewed the labour analgesic and anaesthetic interventions utilised in symptomatic and asymptomatic parturients who had a confirmed positive test for SARS-CoV-2 across 10 hospitals in the north-west of England between 1 April 2020 and 31 May 2021. Primary outcomes analysed included the analgesic/anaesthetic technique utilised for labour and caesarean birth. Secondary outcomes included a comparison of maternal characteristics, caesarean birth rate, maternal critical care admission rate along with adverse composite neonatal outcomes. A positive SARS-CoV-2 test was recorded in 836 parturients with 263 (31.4%) reported to have symptoms of COVID-19. Neuraxial labour analgesia was utilised in 104 (20.4%) of the 509 parturients who went on to have a vaginal birth. No differences in epidural analgesia rates were observed between symptomatic and asymptomatic parturients (OR 1.03, 95%CI 0.64–1.67; p = 0.90). The neuraxial anaesthesia rate in 310 parturients who underwent caesarean delivery was 94.2% (95%CI 90.6–96.0%). The rates of general anaesthesia were similar in symptomatic and asymptomatic parturients (6% vs. 5.7%; p = 0.52). Symptomatic parturients were more likely to be multiparous (OR 1.64, 95%CI 1.19–2.22; p = 0.002); of Asian ethnicity (OR 1.54, 1.04–2.28; p = 0.03); to deliver prematurely (OR 2.16, 95%CI 1.47–3.19; p = 0.001); have a higher caesarean birth rate (44.5% vs. 33.7%; OR 1.57, 95%CI 1.16–2.12; p = 0.008); and a higher critical care utilisation rate both pre- (8% vs. 0%, p = 0.001) and post-delivery (11% vs. 3.5%; OR 3.43, 95%CI 1.83–6.52; p = 0.001). Eight neonates tested positive for SARS-CoV-2 while no differences in adverse composite neonatal outcomes were observed between those born to symptomatic and asymptomatic mothers (25.8% vs. 23.8%; OR 1.11, 95%CI 0.78–1.57; p = 0.55). In women with COVID-19, non-neuraxial analgesic regimens were commonly utilised for labour while neuraxial anaesthesia was employed for the majority of caesarean births. Symptomatic women with COVID-19 are at increased risk of significant maternal morbidity including preterm birth, caesarean birth and peripartum critical care admission.  相似文献   
4.
目的 探讨滋肾育胎丸加减方预防抗磷脂抗体(ACA)阳性者不良妊娠结局的效果及机制研究。方法 选取2016年2月至2019年2月我院收治的89例ACA阳性,先兆性流产或有习惯性流产(RSA)史患者,将采用西医治疗的40例作为对照组,将采用西医联合滋肾育胎丸加减方治疗的49例作为观察组,比较两组中医证候疗效、中医证候积分、ACA-IgA、ACA-IgM、ACA-IgG、凝血指标[血小板聚集功能(PAF)、活化蛋白C(PC)、抗凝血酶(AT)、纤溶酶原激活抑制物-1(PAI-1)]、Th1/Th2细胞因子[干扰素γ(IFN-γ)、白介素-2(IL-2)、白介素-4(IL-4)、白介素-10(IL-10)]、妊娠结局、安全性。结果 治疗2周后检测ACA,观察组2例未降低,对照组11例未降低,观察组未降低患者占比低于对照组(P<0.05);观察组总有效率100.00%高于对照组85.00%(P<0.05);观察组治疗4周、7周后中医证候积分低于对照组(P<0.05);观察组治疗4周、7周后ACA-IgA、ACA-IgM、ACA-IgG低于对照组(P<0.05);观察组治疗4周、7周后PAF、PAI-1低于对照组,PC、AT高于对照组(P<0.05);观察组治疗4周、7周后IFN-γ、IL-2低于对照组,IL-4、IL-10高于对照组(P<0.05);观察组活产率95.92%高于对照组80.00%(P<0.05);组间不良反应总发生率比较,差异无统计学意义(P>0.05)。结论 动态监测ACA对滋肾育胎丸加减方精准应用具有指导意义,指导滋肾育胎丸加减方通过调理脏腑、气血、经络功能,改善先兆性流产或有RSA史患者临床症状及凝血因子指标,降低ACA水平,并可改善患者免疫耐受功能,提高胎儿活产率,且安全性高。  相似文献   
5.
6.
7.
8.
9.
目的对三位一体无缝隙护理在妊娠期高血压中的应用进行观察和分析。方法选择了2018年6月—2018年12月在本院进行了妊娠期高血压护理的60例患者进行研究,对所有患者均采取了三位一体无缝隙护理,对所有患者干预前后血压控制情况、生命质量评分以及心理健康评分进行对比。结果在进行干预之后,患者的血压控制情况、生命质量以及心理健康情况均显著优于干预之前,P<0.05差异有统计学意义。结论在对妊娠期高血压患者护理时,采取三位一体无缝隙护理措施可以对患者血压情况进行控制,缓解患者负面情绪,能够给予患者以及胎儿一定的保障。  相似文献   
10.
In 2008, Brazil's conditional cash transfer program expanded to cover a wider range of ages. Poor families are now given stipends for their children's school attendance up to age seventeen, whereas prior the maximum age was fifteen. Using a nationally representative household survey, we estimate the impact of this policy on teen fertility with a triple difference analysis on the fertility outcomes of treated cohorts vs. non-treated cohorts based on income eligibility, age eligibility, and timing of program implementation. We find a three percentage point drop in fertility among eligible teens within five years of program implementation. This offsets the difference in fertility between poor and non-poor teens. The impact is concentrated in urban areas, with no program effects found in rural areas. We are able to replicate these findings using National Birth Registry Data.  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