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   3626篇
  免费   178篇
  国内免费   24篇
耳鼻咽喉   79篇
儿科学   70篇
妇产科学   80篇
基础医学   471篇
口腔科学   67篇
临床医学   338篇
内科学   913篇
皮肤病学   24篇
神经病学   611篇
特种医学   120篇
外科学   365篇
综合类   8篇
一般理论   2篇
预防医学   167篇
眼科学   35篇
药学   208篇
中国医学   15篇
肿瘤学   255篇
  2023年   29篇
  2022年   61篇
  2021年   92篇
  2020年   59篇
  2019年   83篇
  2018年   101篇
  2017年   76篇
  2016年   106篇
  2015年   98篇
  2014年   148篇
  2013年   182篇
  2012年   268篇
  2011年   238篇
  2010年   151篇
  2009年   135篇
  2008年   244篇
  2007年   239篇
  2006年   234篇
  2005年   246篇
  2004年   221篇
  2003年   192篇
  2002年   191篇
  2001年   25篇
  2000年   19篇
  1999年   28篇
  1998年   56篇
  1997年   29篇
  1996年   16篇
  1995年   33篇
  1994年   19篇
  1993年   19篇
  1992年   16篇
  1991年   12篇
  1990年   17篇
  1989年   18篇
  1988年   9篇
  1987年   11篇
  1986年   8篇
  1985年   13篇
  1984年   13篇
  1983年   7篇
  1982年   16篇
  1981年   7篇
  1980年   8篇
  1979年   6篇
  1978年   3篇
  1976年   3篇
  1974年   8篇
  1973年   4篇
  1970年   3篇
排序方式: 共有3828条查询结果,搜索用时 15 毫秒
31.
Long-term central venous catheters (CVCs) have considerably improved the management of cancer patients because they facilitate chemotherapy, transfusions, parenteral nutrition, and blood sampling. However, the use of long-term CVCs, especially for chemotherapy, has been associated with the occurrence of upper-limb deep venous thrombosis (UL-DVT). The incidence of clinically overt UL-DVT related to CVCs has been reported to vary between 0.3% and 28.3%. The incidence of CVC-related UL-DVT screened by venography reportedly varies between 27% and 66%. The incidence of clinically overt pulmonary embolism (PE) in patients with CVC-related UL-DVT ranges from 15% to 25%, but an autopsy-proven PE rate of up to 50% has been reported. Vessel injury caused by the procedure of CVC insertion, venous stasis caused by the indwelling CVC, and cancer-related hypercoagulability are the main pathogenetic factors for CVC-related venous thromboembolism (VTE). Several studies have assessed the benefit of the prophylaxis of UL-DVT after CVC insertion in cancer patients. According to the results of these studies, prophylaxis with low molecular weight heparin or a low fixed dose of warfarin has been recently proposed. However, the limitations of the experimental design of the prophylactic studies do not allow definitive recommendations. The recommended therapy for UL-DVT associated with CVC is based on anticoagulant therapy with or without catheter removal. This review focuses on the epidemiology, pathogenesis, diagnosis, prevention, and treatment of VTE in cancer patients with long-term CVC.  相似文献   
32.
In the current study, we investigated the effect of the concurrent presentation of saccharin on the maintenance of alcohol-drinking behavior in selectively bred Sardinian alcohol-preferring (sP) rats. Rats were initially given access to alcohol [10% (volume/volume) in water] and water under the home cage, two-bottle, free-choice regimen, with unlimited access for 24 h/day for eight consecutive weeks. Next, a third bottle, containing saccharin [0%, 0.01%, 0.1%, 1%, or 3% (weight/volume) in water], was concomitantly offered for an additional 10 consecutive days. Intake of saccharin solution resulted as an inverted-U function of saccharin concentration, with the 0.1% saccharin solution being the highest accepted. Alcohol intake was a U function of saccharin concentration, being reduced by 65%-95% in the group of rats exposed to the 0.1% saccharin solution. These results indicate that (1) the concurrent presentation of highly palatable solutions of saccharin markedly reduced alcohol intake in alcohol-experienced sP rats and (2) the reducing effect of saccharin solutions on the alcohol intake in sP rats was positively related to their degree of acceptability. We hypothesized that saccharin solutions may have functioned as a reinforcer, partially substituting for alcohol reinforcement and rendering alcohol drinking less urgent.  相似文献   
33.
PURPOSE: The extent of venous thromboembolism (VTE) associated with central vein catheters (CVC) in cancer patients remains unclear. The aim of this study was to evaluate the efficacy and safety of the low molecular weight heparin, enoxaparin, in the prevention of VTE. PATIENTS AND METHODS: In a multicenter, double-blind study, consecutive cancer patients scheduled for CVC insertion were randomly assigned to receive either subcutaneous enoxaparin 40 mg once a day or placebo. Treatment was started 2 hours before CVC insertion and continued for 6 weeks. The primary end points of the study were deep vein thrombosis (DVT), confirmed by venography of the CVC limb performed 6 weeks after randomization, or clinically overt pulmonary embolism, confirmed by objective testing during the study drug administration. Patients were assessed for bleeding complications. RESULTS: Three hundred eighty-five patients were randomized, of which 321 (83.4%) underwent venography. A venography was adequate for adjudication in 155 patients in each treatment group. A DVT was observed in 22 patients (14.1%) treated with enoxaparin and in 28 patients (18.0%) treated with placebo, corresponding to a relative risk of 0.78 (95% CI, 0.47 to 1.31). No major bleeding occurred. Five patients (2.6%) in the enoxaparin group and two patients (1.0%) in the placebo group died during the treatment period. CONCLUSION: In this study, no difference in the rate of CVC-related VTE was detected between patients receiving enoxaparin and patients receiving placebo. The dose of enoxaparin used in this study proved to be safe. Clinical trials evaluating higher enoxaparin doses could optimize the efficacy of this agent for this indication.  相似文献   
34.
Sentinox (STX) is an acid-oxidizing solution containing hypochlorous acid in spray whose virucidal activity against SARS-CoV-2 has been demonstrated. In this paper, results of a randomized controlled trial (RCT) on the efficacy of STX in reducing viral load in mild COVID-19 patients (NCT04909996) and a complementary in vitro study on its activity against different respiratory viruses are reported. In the RCT, 57 patients were randomized (1:1:1) to receive STX three (STX-3) or five (STX-5) times/day plus standard therapy or standard therapy only (controls). Compared with controls, the log10 load reduction in groups STX-3 and STX-5 was 1.02 (p = 0.14) and 0.18 (p = 0.80), respectively. These results were likely driven by outliers with extreme baseline viral loads. When considering subjects with baseline cycle threshold values of 20–30, STX-3 showed a significant (p = 0.016) 2.01 log10 reduction. The proportion of subjects that turned negative by the end of treatment (day 5) was significantly higher in the STX-3 group than in controls, suggesting a shorter virus clearance time. STX was safe and well-tolerated. In the in vitro study, ≥99.9% reduction in titers against common respiratory viruses was observed. STX is a safe device with large virucidal spectrum and may reduce viral loads in mild COVID-19 patients.  相似文献   
35.
ABSTRACT: BACKGROUND: Despite progresses in neonatal care, the mortality and the incidence of neuro-motor disability after perinatal asphyxia have failed to show substantial improvements. In countries with a high level of perinatal care, the incidence of asphyxia responsible for moderate or severe encephalopathy is still 2--3 per 1000 term newborns. Recent trials have demonstrated that moderate hypothermia, started within 6 hours after birth and protracted for 72 hours, can significantly improve survival and reduce neurologic impairment in neonates with hypoxic-ischemic encephalopathy. It is not currently known whether neuroprotective drugs can further improve the beneficial effects of hypothermia. Topiramate has been proven to reduce brain injury in animal models of neonatal hypoxic ischemic encephalopathy. However, the association of mild hypothermia and topiramate treatment has never been studied in human newborns. The objective of this research project is to evaluate, through a multicenter randomized controlled trial, whether the efficacy of moderate hypothermia can be increased by concomitant topiramate treatment. METHODS: Term newborns (gestational age >= 36 weeks and birth weight >= 1800 g) with precocious metabolic, clinical and electroencephalographic (EEG) signs of hypoxic-ischemic encephalopathy will be randomized, according to their EEG pattern, to receive topiramate added to standard treatment with moderate hypothermia or standard treatment alone. Topiramate will be administered at 10 mg/kg once a day for the first 3 days of life. Topiramate concentrations will be measured on serial dried blood spots. 64 participants will be recruited in the study. To evaluate the safety of topiramate administration, cardiac and respiratory parameters will be continuously monitored. Blood samplings will be performed to check renal, liver and metabolic balance. To evaluate the efficacy of topiramate, the neurologic outcome of enrolled newborns will be evaluated by serial neurologic and neuroradiologic examinations. Visual function will be evaluated by means of behavioural standardized tests. DISCUSSION: This pilot study will explore the possible therapeutic role of topiramate in combination with moderate hypothermia. Any favourable results of this research might open new perspectives about the reduction of cerebral damage in asphyxiated newborns. Trial registration Current Controlled Trials ISRCTN62175998; ClinicalTrials.gov Identifier NCT01241019; EudraCT Number 2010-018627-25.  相似文献   
36.
The guiding hypothesis for this work is that in severe intrauterine growth-restricted (IUGR) fetuses, the time from ductus venosus (DV) reversed flow (RF) appearance to intrauterine fetal demise (IUFD) or nonreassuring fetal testing is variable. As such, there must be a transitional phase between the presence of end-diastolic forward flow (FF) and absent or reversed end-diastolic flow (A/REDF). Ductus venosus Doppler was serially studied in 19 IUGR fetuses (estimated fetal weight < 10th percentile and umbilical artery pulsatility index > 95th percentile) from diagnosis until demise or delivery occurring for nonreassuring fetal testing. Ductus venosus waveforms were assessed qualitatively: forward flow versus absent or reversed flow in diastole. Two sets of at least 30 consecutive ductus venosus waveforms were obtained at each examination. If the waveforms differed between the two sets, they were defined as alternating. Cord arterial pH and base excess (BE) were obtained at birth. In 14 cases, DVRF occurred intermittently between periods of FF during the same clinical visit. Intermittent DVRF was present from 2 to 57 days (median, 13 days) and became continuous from 1 to 23 days (median, 7 days) before the occurrence of delivery for nonreassuring fetal testing or fetal demise. One fetus had an abnormal arterial pH (< 7.0) and one had an abnormal BE (< -12). These data show that (1) there is a transitional phase in which DV alternates FF and A/RF before RF becomes persistent; (2) the time from the appearance of DVRF to delivery or IUFD is variable, and (3) not all very preterm IUGR fetuses with continuous DVRF are acidemic. Because of these findings, the decision of delivery regarding early severe IUGR fetuses should be individualized, and the DVRF Doppler information has to be integrated with other antenatal fetal parameters.  相似文献   
37.
The effect of renal impairment (RI) on risk of bleeding and recurrent thrombosis in cancer patients treated with direct oral anticoagulants for venous thromboembolism (VTE) is undefined. We ran a prespecified analysis of the randomized Caravaggio study to evaluate the role of RI as a risk factor for bleeding or recurrence in patients treated with dalteparin or apixaban for cancer-associated VTE. RI was graded as moderate (creatinine clearance between 30-59 mL/minute; 275 patients) and mild (between 60-89 mL/minute; 444 patients). In the 1142 patients included in this analysis, the incidence of major bleeding was similar in patients with moderate vs. no or mild RI (HR 1.06-95% CI: 0.53-2.11), with no difference in the relative safety of apixaban and dalteparin. Recurrent VTE was not different in moderate vs. no or mild RI (HR=0.67, 95% CI: 0.38-1.20); in moderate RI, apixaban reduced recurrent VTE compared to dalteparin (HR=0.27, 95% CI: 0.08-0.96; P for interaction 0.1085). At multivariate analysis, no association was found between variation of renal function over time and major bleeding or recurrent VTE. Advanced or metastatic cancer was the only independent predictor of major bleeding (HR=2.84, 95% CI: 1.20-6.71), with no effect of treatment with apixaban or dalteparin. In our study, in cancer patients treated with apixaban or dalteparin, moderate RI was not associated with major bleeding or recurrent VTE. In patients with moderate renal failure, the safety profile of apixaban was confirmed with the potential for improved efficacy in comparison to dalteparin. ClinicalTrials.gov identifier: NCT03045406.  相似文献   
38.
39.
Respiratory complications are common in the patient with muscular dystrophy. The periodic clinical and instrumental respiratory evaluation is extremely important. Despite the presence in the literature of updated guidelines, patient associations often report lack of knowledge of these pathologies, particularly in peripheral hospitals. The purpose of this work, inspired by the Italian Muscular Dystrophy Association (UILDM) is to improve management of respiratory problems necessary for the management of these patients complex. To this end, the main items that the specialist can meet in the follow-up of these pathologies have been analyzed and discussed, among which the respiratory basal evaluation, the criteria of adaptation to non-invasive ventilation, management of bronchial secretions, situations of respiratory emergency, indications for tracheostomy and the subject of advance directives of treatment (DAT).Key words: respiratory failure, muscular dystrophy, cough efficacy, spirometry, polygraphy, non-invasive ventilation, arterial blood gases, cough machine, invasive ventilation, tracheostomy, mechanical ventilation  相似文献   
40.
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