全文获取类型
收费全文 | 7871篇 |
免费 | 781篇 |
国内免费 | 16篇 |
专业分类
耳鼻咽喉 | 59篇 |
儿科学 | 188篇 |
妇产科学 | 141篇 |
基础医学 | 965篇 |
口腔科学 | 173篇 |
临床医学 | 1330篇 |
内科学 | 1242篇 |
皮肤病学 | 96篇 |
神经病学 | 856篇 |
特种医学 | 172篇 |
外科学 | 1125篇 |
综合类 | 94篇 |
一般理论 | 13篇 |
预防医学 | 945篇 |
眼科学 | 109篇 |
药学 | 660篇 |
中国医学 | 4篇 |
肿瘤学 | 496篇 |
出版年
2023年 | 47篇 |
2022年 | 60篇 |
2021年 | 176篇 |
2020年 | 116篇 |
2019年 | 166篇 |
2018年 | 186篇 |
2017年 | 135篇 |
2016年 | 145篇 |
2015年 | 176篇 |
2014年 | 201篇 |
2013年 | 312篇 |
2012年 | 534篇 |
2011年 | 528篇 |
2010年 | 303篇 |
2009年 | 270篇 |
2008年 | 523篇 |
2007年 | 481篇 |
2006年 | 498篇 |
2005年 | 481篇 |
2004年 | 425篇 |
2003年 | 384篇 |
2002年 | 352篇 |
2001年 | 162篇 |
2000年 | 162篇 |
1999年 | 140篇 |
1998年 | 90篇 |
1997年 | 69篇 |
1996年 | 55篇 |
1995年 | 63篇 |
1994年 | 48篇 |
1993年 | 42篇 |
1992年 | 89篇 |
1991年 | 82篇 |
1990年 | 78篇 |
1989年 | 83篇 |
1988年 | 74篇 |
1987年 | 79篇 |
1986年 | 73篇 |
1985年 | 49篇 |
1984年 | 59篇 |
1983年 | 54篇 |
1982年 | 31篇 |
1981年 | 34篇 |
1979年 | 44篇 |
1978年 | 40篇 |
1976年 | 30篇 |
1973年 | 30篇 |
1972年 | 34篇 |
1971年 | 28篇 |
1969年 | 30篇 |
排序方式: 共有8668条查询结果,搜索用时 46 毫秒
1.
2.
3.
Stuart J. Dilley Tracey J. Weiland Robert O’Brien Neil J. Cunningham Julian E. Van Dijk Rosie M. Mahoney 《Teaching and learning in medicine》2015,27(1):71-79
Theory: Immersive simulation is a common mode of education for medical students. Observation of clinical simulations prior to participation is believed to be beneficial, though this is often a passive process. Active observation may be more beneficial. Hypotheses: The hypothesis tested in this study was that the active use of a simple checklist during observation of an immersive simulation would result in better participant performance in a subsequent scenario compared with passive observation alone. Methods: Medical students were randomized to either passive or active (with checklist) observation of an immersive simulation involving cardiac arrest prior to participating in their own simulation. Performance measures included time to cardiopulmonary resuscitation (CPR) and time to defibrillation and were compared between first and second scenarios as well as between passive and active observers. Results: Seventy-nine simulations involving 232 students were conducted. Mean time to CPR was 18 seconds (SD = 11.6) for those using the checklist and 24 seconds (SD = 15.8) for those who observed passively (M difference = 6 seconds), t(35) = 1.46, p =.153. Time to defibrillation was 94 seconds (SD = 26.4) for those using the checklist and 92 seconds (SD = 23.8) for those who observed passively (M difference = –2 seconds), t(38) =.21, p =.837. Time to CPR was 24 seconds (SD = 15.8) for passive observers and 31 seconds (SD = 21.0; M difference = 7 seconds), t(35) = 1.13, p =.265, for their first scenario counterparts. Time to CPR was 18 seconds (SD = 11.6) for active observers and 36 seconds (SD = 26.2; M difference = 18 seconds), t(24) = 2.81, p =.010, for their first scenario counterparts. Time to defibrillation was 92 seconds (SD = 23.8) for passive observers and 125 seconds (SD = 32.2; M difference = 33 seconds), t(33) = 3.63, p =.001, for their first scenario counterparts. Time to defibrillation was 94 seconds (SD = 26.4) for the active observers and 132 seconds (SD = 52.9; M difference = 38 seconds), t(28) =.46, p =.008, for their first scenario counterparts. Conclusions: Observation alone leads to improved performance in the management of a simulated cardiac arrest. The active use of a simple skills-based checklist during observation did not appear to improve performance over passive observation alone. 相似文献
4.
5.
6.
7.
8.
Serotonin (5-HT) is a mediator (through 5-HT1P receptors) of slow EPSPs in myenteric ganglia of the small intestine. The effect of 5-HT can be mimicked by elevating cAMP; therefore, we tested the hypothesis that the slow EPSP-like response to 5-HT is cAMP-mediated. Guinea pig gut was enzymatically dissociated; myenteric ganglia remained intact and were collected by filtration. Neurons in the isolated ganglia retained their ability to manifest the slow EPSP-like response to 5-HT. Exposure to 5-HT raised the ganglionic level of cAMP (ED50 0.3 μM). This effect was not antagonized by the 5-HT1P antagonist, N-acetyl-5-hydroxytryptophyl-5-hydroxytryptophan amide (100.0 μM), or mimicked by the 5-HT1P agonist, 5-hydroxyindalpine (10.0 μM). Increases in cAMP were also evoked by the 5-HT1 agonist, 5-carboxyamidotryptamine (10.0 μM), the 5-HT2 agonist, (±)-1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI; 1.0–10.0 μM), and by the 5-HT4 agonists, renzapride (1.0–10.0 μM) and 5-methoxytryptamine (1.0–10.0 μM); however, neither the 5-HT1/5-HT2 antagonists, spiperone, methysergide, and methiothepin, nor the 5-HT4 antagonist, tropisetron (ICS 205–930; 10.0 μM), were able to inhibit the rise in cAMP evoked by these compounds or by 5-HT (0.1–10.0 μM). The 5-HT-evoked elevation of cAMP was antagonized by ketanserin (10.0 μM), which also blocked the effects of 5-methoxytryptamine and DOI, but not those of renzapride. The effective concentration of DOI, however, was higher than that needed for activation of 5-HT2 receptors, and Northern analysis using a cDNA probe encoding the rat 5-HT2 receptor failed to reveal the presence of 5-HT2 mRNA in myenteric ganglia, although it hybridizes with mRNA of the right size in the guinea pig brain. Compounds that failed to change levels of cAMP or to antagonize the action of 5-HT included 8-hydroxy-di-n-propylamino tetralin, R58639, R88226, and sumatriptan. It is concluded that the receptor responsible for the 5-HT-induced rise in cAMP in ganglia isolated from the guinea pig myenteric plexus is not a known subtype of 5-HT receptor. Since the pharmacology of this novel receptor is different from that of the slow EPSP-like response to 5-HT, the receptor probably does not mediate the slow EPSP. © 1993 Wiley-Liss, Inc. 相似文献
9.
Intratemporal vascular tumors: detection with CT and MR imaging 总被引:1,自引:0,他引:1
Lo WW; Shelton C; Waluch V; Solti-Bohman LG; Carberry JN; Brackmann DE; Wade CT 《Radiology》1989,171(2):445-448
The diagnostic contributions of computed tomography (CT) and magnetic resonance (MR) imaging were compared in 12 patients with benign intratemporal vascular tumors (hemangioma or vascular malformation). The tumors included six in the internal acoustic canal and six in the geniculate ganglion region. Clinical and histologic correlations were made. Two of the six patients with tumors in the internal acoustic canal underwent CT, and both required gas cisternography to show the tumor. Five patients in that group underwent MR imaging, and all five studies showed the tumor. All six patients with geniculate ganglion tumors underwent CT. Results in one study were questionable, and five showed the tumor. Five patients in this group underwent MR imaging, but the MR findings were positive in only two cases. MR imaging should therefore be performed before CT in the evaluation of facial nerve dysfunction, as it demonstrated all tumors in the internal acoustic canal and some in the geniculate ganglion region. If MR findings are negative, CT should then be performed to rule out a possible geniculate ganglion lesion. 相似文献