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   6882篇
  免费   582篇
  国内免费   185篇
耳鼻咽喉   8篇
儿科学   698篇
妇产科学   124篇
基础医学   535篇
口腔科学   5篇
临床医学   689篇
内科学   1077篇
皮肤病学   7篇
神经病学   1672篇
特种医学   301篇
外科学   213篇
综合类   1099篇
预防医学   405篇
眼科学   21篇
药学   550篇
  4篇
中国医学   175篇
肿瘤学   66篇
  2023年   116篇
  2022年   161篇
  2021年   291篇
  2020年   273篇
  2019年   271篇
  2018年   252篇
  2017年   238篇
  2016年   299篇
  2015年   258篇
  2014年   491篇
  2013年   443篇
  2012年   437篇
  2011年   465篇
  2010年   325篇
  2009年   345篇
  2008年   303篇
  2007年   345篇
  2006年   337篇
  2005年   233篇
  2004年   191篇
  2003年   176篇
  2002年   176篇
  2001年   155篇
  2000年   119篇
  1999年   93篇
  1998年   84篇
  1997年   80篇
  1996年   62篇
  1995年   63篇
  1994年   65篇
  1993年   58篇
  1992年   48篇
  1991年   53篇
  1990年   27篇
  1989年   34篇
  1988年   27篇
  1987年   28篇
  1986年   34篇
  1985年   31篇
  1984年   28篇
  1983年   15篇
  1982年   14篇
  1981年   20篇
  1980年   25篇
  1979年   18篇
  1978年   8篇
  1977年   9篇
  1975年   7篇
  1972年   3篇
  1968年   4篇
排序方式: 共有7649条查询结果,搜索用时 156 毫秒
1.
2.
Continuous utero-placental circulation, and patent umbilical blood vessels ensure an uninterrupted transfer of oxygen and nutrients to the fetus as well as clearance of metabolic waste products. The onset of labour characterized by progressive and strong uterine contractions poses a threat to fetal oxygenation as a result of collapsing the spiral arterioles traversing the myometrium to supply the placental bed, and repetitive compression of the blood vessels within the umbilical cord. Human fetuses are equipped with compensatory mechanisms to cope with transient interruptions of blood supply during labour. The ability to compensate may be blunted in cases of poor fetal reserves, increased metabolic demand (macrosomia or maternal fever), and due to non-hypoxic pathways (e.g. chorioamniontis or fetal hypovolumia-hypotension syndrome). Intrapartum fetal surveillance involves prompt recognition of the features that signal the onset of fetal decompensation on the cardiotocograph (CTG) to ensure a timely intervention to avoid hypoxic-ischaemic encephalopathy (HIE) or perinatal deaths. This article summarises a ‘physiological approach’ to the interpretation of the CTG which, in places, conflicts with other current UK guidance.  相似文献   
3.
PurposeTo assess the critical role of transjugular intrahepatic portosystemic shunt (TIPS) in the management of Budd-Chiari syndrome (BCS), as the data with respect to the safety and outcome of TIPS in patients with BCS are scarce because of the rarity of the disease.Materials and MethodsA comprehensive search of literature of various databases from 2000 to October 2021 was conducted for studies evaluating the outcome of TIPS in patients with BCS. The primary outcomes of the analysis were technical and clinical success, adverse events and mortality associated with TIPS, dysfunction of TIPS, need for TIPS revision, need for liver transplantation (LT), and 1-year survival.ResultsA total of 33 studies (1,395 patients) were included in this meta-analysis. The pooled rates and 95% confidence intervals of various outcomes were 98.6% (97.6–99.7) for technical success, 90.3% (86.0–94.6) for clinical success, 10.0% (6.5–13.6) for major adverse events, 0.5% (0.2–1.0) for TIPS-related mortality, 11.6% (7.8–15.4) for post-TIPS hepatic encephalopathy (HE), 40.1% (32.5–47.7) for TIPS dysfunction, 8.6% (4.9–12.4) for the need for TIPS revision, 4.5% (2.8–6.2) for the need for LT, and 94.6% (93.1–96.1) for 1-year survival. Publication bias was seen with all outcomes except for post-TIPS HE, TIPS dysfunction, and the need for LT.ConclusionsThe existing literature supports the feasibility, safety, and efficacy of TIPS in the treatment of BCS. Deciding the optimal timing of TIPS in BCS needs further studies.  相似文献   
4.
5.
Background: Even key opinion leaders now concede that electronic fetal monitoring (EFM) cannot reliably identify fetal acidemia which many vouch as the only labor mediated pathophysiologic precursor for cerebral palsy (CP). We have developed the “Fetal Reserve Index” – an algorithm combining five dynamic components of EFM (1. Rate, 2. Variability, 3. Accelerations, 4. Decelerations, and 5. Excessive uterine activity) considered individually that are combined with the presence of: 6. maternal, 7. obstetrical, and 8. fetal risk factors.

Objective: Here, we compare this 8-point fetal reserve index (FRI) against the performance of ACOG monograph criteria and ACOG Category systems for predicting risk for both CP and the need for emergency operative delivery (EOD). We then studied how varied management for screen positives (Red zone-defined below) impacts the outcome of such cases.

Study design: Four hundred twenty term patients were studied: all entered labor with normal EFMs and no apparent cause of harm except events of labor and delivery. Sixty subsequently developed CP, and 360 were apparently normal controls. An FRI, normal on all eight parameters scored 100%, 4 of the 8 was 50%, etc. We divided cases into Green zone >50%, Yellow 50–26%, and Red ≤25%. An FRI in the Red zone was considered a positive screen. We then compared performance metrics for the three evaluation schemes and differences between controls that reached Red against those controls whose worst scores were Green/Yellow.

Results: For detection of injury during labor, the FRI performed much better than the ACOG Category criteria (sensitivity 28%), and Category III (45%) (p?Conclusions: FRI shows better discrimination for adverse fetal outcome and EOD than traditional EFM interpretation. The Category system is a very poor, subjective screening method as the vast majority of CP babies never reach the “action point” result of Category III. While reaching the Red zone does not ordain a bad outcome, how it is managed, does. Compared to CP cases, Red controls were delivered faster, had higher FRIs, and often had prompt management including IR maneuvers, which improved the FRI and lowered the risk of EODs even for cases with normal outcomes. With further study and validation, the quantitative FRI approach may replace the current, very subjective interpretation with a quantitative “lab test” approach.  相似文献   
6.
目的探讨伴岛叶三层现象(TA)的急性坏死性脑病(ANE)临床及遗传学特征。方法回顾分析1个确诊为ANE家系的临床资料。结果先证者为男性,4.5岁时以惊厥、意识障碍起病,1岁时有热性惊厥史;头颅磁共振示对称性多灶性损害,岛叶存在TA。家系中有6例患者,起病年龄6月龄至50岁,主要以发热后惊厥或惊厥持续状态及意识障碍起病,3例因惊厥持续状态死亡;免疫治疗及能量支持可改善预后。基因检测发现家系RANBP2基因变异(NM_006267;c.1754 CT[p.T585M])。结论首次报道TA可出现于岛叶。  相似文献   
7.
Introduction and aimsCirrhosis is the common outcome of liver diseases. It can be decompensated and lead to the development of complications, such as encephalopathy. Hyperammonemia that develops due to liver dysfunction is etiopathologically related to hepatic encephalopathy. Caffeine increases the activity of the urea cycle in the liver, augmenting ammonia degradation. By antagonizing adenosine receptors, it also has a hepatoprotective effect, impeding the formation of fibrosis, as well as having a stimulating effect on the central nervous system. The present study analyzed the effects of caffeine on the progression of cholestatic liver fibrosis and hepatic encephalopathy.Materials and methodsAn experimental model of cholestatic liver fibrosis, through common bile duct ligature, and of hepatic encephalopathy, through the administration of a high-protein diet, was constructed. Male Wistar rats (n = 32) were equally divided into 4 groups. The experiment lasted 28 days, with the administration of 50 mg/kg/day of caffeine. Laboratory tests, histologic analyses of the liver and encephalon, open field tests (OFTs), and daily behavioral analyses were carried out.ResultsThe ligated animals treated with caffeine had lower mean transaminase levels and improved histologic aspects of the liver and encephalon. The untreated ligated animals were clearly lethargic and apathetic at the last week of the experiment, confirmed by reduced exploratory activity during the OFT.ConclusionCaffeine improved the microarchitecture of the liver and encephalon of the cirrhotic animals and prevented the decrease in exploratory behavior of the animals during the OFT.  相似文献   
8.
Neonatal encephalopathy (NE) is a significant complication of the peripartum period. It can lead to lifelong neurologic disabilities, including cerebral palsy, cognitive impairments, developmental delays, and epilepsy. Induced hypothermia is the first therapy, which has shown promise in improving the outcomes for neonates with moderate to severe NE following a presumed intrapartum insult.NE is also a frequent source of medical malpractice litigation. In this paper, we will review salient features of the American Tort System as it pertains to medical malpractice. We will discuss the obstetric medico-legal implications of therapeutic hypothermia and suggest a five-step approach to analyzing neonatal cases for causation, etiology, timing of occurrence, responsibility, and liability. We will close with three illustrative clinical cases.  相似文献   
9.
Neonates and families face challenges in hypothermic therapy, including trauma to parents, extreme emotions, and unfamiliarity with the medical system. Communication is an essential element to supporting parents while their children are in the NICU, and beyond, building the foundation for the ongoing relationship the family has with the medical system. Significant consideration needs to be given to the critical element of integrating the family into the care of a baby being treated with therapeutic hypothermia. Clinicians can promote healing of accumulated traumas of parents through ensuring parent's emotional safety, facilitating a trusting relationship, and promoting parent empowerment. Connecting parents with resources, especially peer support, is an essential part of a hospital stay. In this chapter, we explore best practices to support families during and after hypothermic therapy.  相似文献   
10.
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