收费全文 | 5692篇 |
免费 | 196篇 |
国内免费 | 52篇 |
耳鼻咽喉 | 67篇 |
儿科学 | 45篇 |
妇产科学 | 66篇 |
基础医学 | 174篇 |
口腔科学 | 55篇 |
临床医学 | 588篇 |
内科学 | 227篇 |
皮肤病学 | 28篇 |
神经病学 | 122篇 |
特种医学 | 68篇 |
外科学 | 1997篇 |
综合类 | 1292篇 |
预防医学 | 345篇 |
眼科学 | 42篇 |
药学 | 676篇 |
8篇 | |
中国医学 | 88篇 |
肿瘤学 | 52篇 |
2024年 | 14篇 |
2023年 | 50篇 |
2022年 | 157篇 |
2021年 | 160篇 |
2020年 | 141篇 |
2019年 | 133篇 |
2018年 | 120篇 |
2017年 | 179篇 |
2016年 | 194篇 |
2015年 | 191篇 |
2014年 | 418篇 |
2013年 | 379篇 |
2012年 | 343篇 |
2011年 | 474篇 |
2010年 | 313篇 |
2009年 | 299篇 |
2008年 | 286篇 |
2007年 | 241篇 |
2006年 | 253篇 |
2005年 | 188篇 |
2004年 | 151篇 |
2003年 | 140篇 |
2002年 | 115篇 |
2001年 | 99篇 |
2000年 | 85篇 |
1999年 | 71篇 |
1998年 | 61篇 |
1997年 | 72篇 |
1996年 | 38篇 |
1995年 | 73篇 |
1994年 | 53篇 |
1993年 | 48篇 |
1992年 | 52篇 |
1991年 | 40篇 |
1990年 | 53篇 |
1989年 | 46篇 |
1988年 | 30篇 |
1987年 | 54篇 |
1986年 | 26篇 |
1985年 | 23篇 |
1984年 | 13篇 |
1983年 | 4篇 |
1982年 | 15篇 |
1981年 | 5篇 |
1980年 | 4篇 |
1979年 | 5篇 |
1978年 | 5篇 |
1977年 | 5篇 |
1973年 | 7篇 |
1969年 | 3篇 |
Design: Prospective, randomized study.
Setting: Teaching hospital.
Patients: 600 ASA physical status I and II parturients scheduled for labor and delivery or elective cesarean section.
Interventions: After identification of the epidural space with pulsations of an air-fluid column, parturients for vaginal delivery (n = 380) were randomized to receive a test dose of 3 ml 3% 2-chloroprocaine with epinephrine 20 μg, two doses of 7 ml bupivacaine 0.03 % with sufentanil 1 μg/ml and epinephrine 2 μg/ml by either gravity flow (Group 1) given over 30 seconds or by bolus injection (Group 2) given over 5 seconds through the epidural needle; parturients for Cesarean delivery (n = 220) were randomized to receive a test dose and two doses of 6 ml lidocaine 2 % with sufentanil 1 μg/ml and epinephrine 2 μg/ml by either gravity flow or by bolus injection through the epidural needle. Changes in maternal heart rate (HR) and blood pressure, signs of intravascular injection, and adverse effects of epidural bupivacaine-sufentanil were recorded after each dose.
Measurements and Main Results: Gravity flow administration (Group 1) was associated with a smaller increase in mean maternal HR (p < 0.001), less hypotension (p < 0.01), sedation (p < 0.01), nausea (p = 0.01), and segmental spread (p < 0.0001) than were corresponding doses given by traditional bolus injection (Group 1) for vaginal or Cesarean deliveries. The incidence of systemic toxicity was zero of 300 (0%) with gravity flow and 4 of 300 (1.3%) by bolus injection, p = 0.12, Fisher's exact test. No patient in either group had an accidental intrathecal injection.
Conclusion: Gravity flow administration of local anesthetic-opioid solution during epidural block for obstetrics was associated with fewer signs of systemic drug absorption and cardiovascular perturbations than was the traditional bolus injection. This study supports the current opinion that slow administration of local anesthetic during epidural black contributes to fewer adverse events. 相似文献
Methods: Serum interleukin-6 in parturients was measured on hospital admission, immediately after birth and 12 and 24 hours later. All parturients had uncomplicated pregnancies, and delivered vaginally without (n=31) or with (n=20) epidural analgesia, or underwent Caesarean section under epidural (n=20) or general (n=10) anaesthesia.
Results: Serum interleukin-6 assayed immediately following Caesarean section was low, but peaked 12 hours later, irrespective of the anaesthetic technique or other foetomaternal characteristics. Patients who delivered vaginally showed the highest interleukin-6 levels immediately after delivery. These were positively correlated with serum interleukin-6 on admission and duration of labour. Serum interleukin-6 was significantly higher in parturients who had epidural analgesia, and was significantly lower in those receiving intravaginal prostaglandins compared to those without prostaglandins.
Conclusion: The interleukin-6 response after Caesarean section can be explained by a generalized acute phase response to surgery, with no anaesthetic, maternal or neonatal interference. The rapid increase in peripartum serum interleukin-6 levels after vaginal delivery reflects, in part, cervical ripening or labour, their physiological triggers and psychological or physical stress. Regional anaesthesia, duration of labour and exogenous prostaglandin administration can modulate the peripartum interleukin-6 response and subsequently the physiological effects of this cytokine. 相似文献
Results: Compared to equianesthetic sevoflurane, xenon produced a faster induction of anesthesia (14759 versus 71221 s, respectively) with smaller decreases in respiratory rate, tidal volume and minute ventilation. Both agents showed comparable cardiovascular stability and oxygen saturation during induction. One patient in the sevoflurane group had breath-holding and movements of extremities and another had only breath-holding. No patients in the xenon group experienced any complications.
Conclusion: Xenon produced a faster induction of anesthesia without any complications than sevoflurane. Xenon had smaller decreases in tidal volume and respiratory rate during induction than sevoflurane. Xenon might offer an alternative to sevoflurane for an inhalation induction.
Method Twenty-four adult ASA 1–2 patients premedicated with 0.05 mg/kg of midazolam were instructed to take vital capacity breaths of 1 minimum alveolar concentration (MAC) of either xenon or sevoflurane until they lost consciousness. Induction time, total ventilatory volume, tidal volume, respiratory rate, minute ventilation, end-tidal MAC fraction, cardiovascular parameters and oxygen saturation were recorded. The patients were interviewed on the following day to evaluate their acceptability rating of the inhalation inductions. 相似文献