全文获取类型
收费全文 | 157512篇 |
免费 | 9891篇 |
国内免费 | 2353篇 |
专业分类
耳鼻咽喉 | 1848篇 |
儿科学 | 6909篇 |
妇产科学 | 3783篇 |
基础医学 | 12623篇 |
口腔科学 | 4794篇 |
临床医学 | 17112篇 |
内科学 | 33082篇 |
皮肤病学 | 3648篇 |
神经病学 | 8837篇 |
特种医学 | 7178篇 |
外国民族医学 | 46篇 |
外科学 | 29683篇 |
综合类 | 10727篇 |
现状与发展 | 4篇 |
预防医学 | 7560篇 |
眼科学 | 2713篇 |
药学 | 7823篇 |
75篇 | |
中国医学 | 2212篇 |
肿瘤学 | 9099篇 |
出版年
2023年 | 4221篇 |
2022年 | 5295篇 |
2021年 | 7657篇 |
2020年 | 6497篇 |
2019年 | 13335篇 |
2018年 | 10420篇 |
2017年 | 6255篇 |
2016年 | 3441篇 |
2015年 | 4047篇 |
2014年 | 5940篇 |
2013年 | 4714篇 |
2012年 | 3528篇 |
2011年 | 7147篇 |
2010年 | 3428篇 |
2009年 | 3676篇 |
2008年 | 3885篇 |
2007年 | 3633篇 |
2006年 | 2959篇 |
2005年 | 3281篇 |
2004年 | 3014篇 |
2003年 | 2343篇 |
2002年 | 2700篇 |
2001年 | 3001篇 |
2000年 | 3874篇 |
1999年 | 4064篇 |
1998年 | 3759篇 |
1997年 | 2752篇 |
1996年 | 1994篇 |
1995年 | 1533篇 |
1994年 | 1508篇 |
1993年 | 1091篇 |
1992年 | 1062篇 |
1991年 | 931篇 |
1990年 | 906篇 |
1989年 | 661篇 |
1988年 | 700篇 |
1987年 | 461篇 |
1985年 | 2897篇 |
1984年 | 4171篇 |
1983年 | 2952篇 |
1982年 | 2929篇 |
1981年 | 2741篇 |
1980年 | 2420篇 |
1979年 | 2239篇 |
1978年 | 1832篇 |
1977年 | 1591篇 |
1976年 | 1712篇 |
1975年 | 1448篇 |
1974年 | 1277篇 |
1973年 | 1208篇 |
排序方式: 共有10000条查询结果,搜索用时 218 毫秒
51.
52.
53.
54.
Aaron Pitzele Mohammad Rahimi Eric Armbrecht 《The journal of maternal-fetal & neonatal medicine》2015,28(15):1770-1773
Objective: To determine whether packed red blood cell (PRBC) transfusion affects post-prandial superior mesenteric artery blood flow velocities (SMA BFVs) in very-low birth weight (VLBW) neonates and if so, at what time point after transfusion restoration of previous SMA BFV patterns occurs.Design/Methods: VLBW pre-term neonates, older than 14 days and tolerating bolus enteral feedings administered every 3?h were enrolled in this prospective observational study. Pulsed Doppler ultrasound was used to measure pre- and post-prandial (at 45?min) time-averaged mean, peak and end diastolic velocities (TAMV, PSV, EDV) immediately before and after 15?ml/kg of PRBC transfusion was given over 3?h; patent ductus arteriosus (PDA) status was also evaluated. Subsequent pre- and post-prandial SMA BFVs were recorded 24 and 48?h after the transfusion.Results: Pre- and post-prandial measurements were obtained for 21 out of 25 enrolled infants. Post-prandial SMA BFVs were attenuated during the feedings immediately after transfusion; at 24 and 48?h after transfusion, changes in post-prandial SMA BFVs were similar to those measured prior to transfusion; the presence of the PDA did not affect results.Conclusions: PRBC transfusion blunted SMA BFV responses to feedings immediately after the transfusion with normalization observed 24?h post-transfusion. 相似文献
55.
56.
《Vaccine》2020,38(45):7118-7128
IntroductionToward the Global Vaccine Action Plan 2020 goal, almost 90% of countries have established a National Immunization Technical Advisory Group (NITAG). However, little is known about NITAG's contributions to governance.MethodsIn 2017–2018, a two-step, qualitative retrospective study was conducted. Jordan (JO), Argentina (AR), and South Africa (SA) were selected owing to government-financed NITAGs from middle-income countries (MICs), geographic diversity, and a vaccine introduction with NITAG support. Country case studies were developed, collecting data through desk review and face-to-face key informant interviews (KIIs) from Ministry of Health (MoH) and NITAG. Case studies were analyzed together, to assess governance applying the European Observatory on Health Systems and Policies framework focusing on transparency, accountability, participation, integrity, and policy capacity (TAPIC).ResultsDocument review and 53 KII (22 AR, 20 SA, 11 JO) showed NITAGs played a pivotal role as advisors promoting a culture of evidence-informed policies. NITAGs strengthened governance, although practices varied among countries. Meetings were conducted behind-closed-doors, participation restricted to members, only in one country agendas, and recommendations were public (AR). To increase participation, policy capacity, and transparency, countries considered adding experts in communications, advocacy, and economics. AR and SA contemplated including community members. NITAGs functioned autonomously from the government, with no established internal or external monitoring or supervision. NITAG meeting minutes allowed the review of integrity, adherence to terms of reference, standard operating procedures, and conflict of interest (CoI). For the most part, NITAGs abided by their mandates. Significant issues were related to the level of MoH support and oversight of CoI declaration and documentation.ConclusionsSystematically implementing governance approaches could improve processes, better tailor policies, and implementation. The long-term survival and resilience of NITAGs in these countries showed they play a significant role in strengthening governance. Lessons learned could be useful to those promoting country-driven evidence-informed decision-making. 相似文献
57.
58.
59.
《Clinical neurophysiology》2020,131(1):259-264
ObjectivesFasciculation potentials (FP) are an important consideration in the electrophysiological diagnosis of ALS. Muscle ultrasonography (MUS) has a higher sensitivity in detecting fasciculations than electromyography (EMG), while in some cases, it is unable to detect EMG-detected fasciculations. We aimed to investigate the differences of FP between the muscles with and without MUS-detected fasciculations (MUS-fas).MethodsThirty-one consecutive patients with sporadic ALS were prospectively recruited and in those, both needle EMG and MUS were performed. Analyses of the amplitude, duration, and number of phases of EMG-detected FPs were performed for seven muscles per patient, and results were compared between the muscles with and without MUS-fas in the total cohort.ResultsThe mean amplitude and phase number of FP were significantly lower in patients with EMG-detected FP alone (0.39 ± 0.25 mV and 3.21 ± 0.88, respectively) than in those with both FP and MUS-fas (1.22 ± 0.92 mV and 3.74 ± 1.39, respectively; p < 0.0001 and p = 0.017, Welch’s t-test).ConclusionSmall FP may be undetectable with MUS. MUS cannot replace EMG in the diagnostic approach for ALS.SignificanceClinicians should use a combination of EMG and MUS for the detection and quantitative analysis of fasciculation in ALS. 相似文献
60.
《Clinical neurophysiology》2020,131(4):859-865
ObjectiveWe examined selected peripheral and spinal nerves of children aged between two and seven years.MethodHigh resolution ultrasound was performed in 116 children (2–7 years of age) at 19 predefined landmarks of median, ulnar, tibial, fibular, sural and radial nerves, the vagus as well as cervical spinal nerve 5 and 6. Further, side-to-side measuring and grey-scale analysis was done at selected nerve sites.ResultsNerves of children were on average smaller than those of adults. Nerve growth correlates significantly with age in all nerves, the mean values were similar in the age of two to four years and five to seven years. Body mass index (BMI) and gender showed moderate effect at some nerve sites, however not uniformly in all. A side-to-side difference of up to 30% in median, and up to 20% in tibial nerve can occur in healthy individuals. Grey-scale analysis for echointensity has been performed in median, ulnar and tibial nerves.ConclusionNerve size increases with age, BMI and gender have moderate effect. A side-to-side-difference of up to 30% can exist.SignificanceReference values of nerve cross-sectional area, side-to-side-difference and echo intensity are necessary to detect nerve pathology in children as well as in adults. 相似文献