全文获取类型
收费全文 | 77643篇 |
免费 | 5703篇 |
国内免费 | 212篇 |
专业分类
耳鼻咽喉 | 1024篇 |
儿科学 | 1971篇 |
妇产科学 | 1795篇 |
基础医学 | 12598篇 |
口腔科学 | 1834篇 |
临床医学 | 7475篇 |
内科学 | 16114篇 |
皮肤病学 | 1346篇 |
神经病学 | 7349篇 |
特种医学 | 3277篇 |
外国民族医学 | 55篇 |
外科学 | 10453篇 |
综合类 | 570篇 |
一般理论 | 88篇 |
预防医学 | 5576篇 |
眼科学 | 1397篇 |
药学 | 5525篇 |
中国医学 | 176篇 |
肿瘤学 | 4935篇 |
出版年
2022年 | 603篇 |
2021年 | 1638篇 |
2020年 | 982篇 |
2019年 | 1423篇 |
2018年 | 1745篇 |
2017年 | 1182篇 |
2016年 | 1375篇 |
2015年 | 1615篇 |
2014年 | 2042篇 |
2013年 | 3163篇 |
2012年 | 4257篇 |
2011年 | 4333篇 |
2010年 | 2898篇 |
2009年 | 2479篇 |
2008年 | 3738篇 |
2007年 | 3851篇 |
2006年 | 3693篇 |
2005年 | 3485篇 |
2004年 | 3442篇 |
2003年 | 3098篇 |
2002年 | 3104篇 |
2001年 | 2260篇 |
2000年 | 2310篇 |
1999年 | 2071篇 |
1998年 | 957篇 |
1997年 | 788篇 |
1996年 | 700篇 |
1995年 | 722篇 |
1994年 | 599篇 |
1993年 | 641篇 |
1992年 | 1502篇 |
1991年 | 1454篇 |
1990年 | 1390篇 |
1989年 | 1366篇 |
1988年 | 1135篇 |
1987年 | 1138篇 |
1986年 | 1078篇 |
1985年 | 979篇 |
1984年 | 718篇 |
1983年 | 679篇 |
1982年 | 492篇 |
1981年 | 454篇 |
1980年 | 393篇 |
1979年 | 642篇 |
1978年 | 390篇 |
1977年 | 370篇 |
1975年 | 379篇 |
1974年 | 428篇 |
1973年 | 357篇 |
1972年 | 353篇 |
排序方式: 共有10000条查询结果,搜索用时 171 毫秒
11.
12.
Bielik Peter Bonczek Ondřej Krejčí Přemysl Zeman Tomáš Izakovičová-Hollá Lydie Šoukalová Jana Vaněk Jiří Vojtěšek Bořivoj Lochman Jan Balcar Vladimir J. Šerý Omar 《Clinical oral investigations》2022,26(12):7045-7055
Clinical Oral Investigations - The aim of this study was the analysis of WNT10A variants in seven families of probands with various forms of tooth agenesis and self-reported family history of... 相似文献
13.
W. Do T. Elzerman R. de Bree A. Rosenberg T. Forouzanfar E.M. Van Cann 《International journal of oral and maxillofacial surgery》2021,50(5):591-597
The aim of this study was to analyse the effect of body mass index (BMI), both low and high values, on the perioperative complication rate in patients with oral squamous cell carcinoma (OSCC). The medical records of 259 patients operated between 2014 and 2017 for OSCC were reviewed. Univariate and multivariate analyses were performed. Sixty of the 259 patients developed 87 complications. Low or high BMI was not associated with the perioperative complication rate. A longer operating time and increased blood loss were associated with a higher perioperative complication rate and higher Clavien–Dindo grade. Low BMI, American Society of Anesthesiologists score 2 and 3, a longer operating time, and increased blood loss were associated with a longer hospital stay. Low BMI was associated with a longer hospital stay. Neither low nor high BMI was associated with the perioperative complication rate. A longer operating time and increased blood loss were associated with a higher perioperative complication rate and higher Clavien–Dindo grade. 相似文献
14.
Discrete choice experiments (DCEs) are frequently used in health economics to measure preferences for nonmarket goods. Best–worst discrete choice experiment (BWDCE) has been proposed as a variant of the traditional “pick the best” approach. BWDCE, where participants choose the best and worst options, is argued to generate more precise preference estimates because of the additional information collected. However, the validity of the approach relies on two necessary conditions: (a) best and worst decisions provide similar information about preferences and (b) asking individuals to answer more than one choice question per task does not reduce data quality. Whether these conditions hold in empirical applications remains under researched. This is the first study to compare participants' choices across three experimental conditions: (a) BEST choices only, (b) WORST choices only, and (c) BEST and WORST choices (BWDCE). We find responses to worst choices are noisier. Implied preferences from the best only and worst only choices are qualitatively different, leading to different WTP values. Responses to BWDCE tasks have lower consistency, and respondents are more likely to use simplifying decision heuristics. We urge caution in using BWDCE as an alternative to the traditional “pick the best” DCE. 相似文献
15.
Toshiro Hara Rony Chanoch-Myers Nathan D. Mathewson Chad Myskiw Lyla Atta Lillian Bussema Stephen W. Eichhorn Alissa C. Greenwald Gabriela S. Kinker Christopher Rodman L. Nicolas Gonzalez Castro Hiroaki Wakimoto Orit Rozenblatt-Rosen Xiaowei Zhuang Jean Fan Tony Hunter Inder M. Verma Kai W. Wucherpfennig Itay Tirosh 《Cancer cell》2021,39(6):779-792.e11
- Download : Download high-res image (228KB)
- Download : Download full-size image
16.
Quang Ngoc Nguyen Linh Dieu Vuong Van-Long Truong To Van Ta Nam Trung Nguyen Hung Phi Nguyen Ha Hoang Chu 《Pathology, research and practice》2019,215(5):885-892
Genetic and epigenetic alterations importantly contribute to the pathogenesis of lung cancer. In the study, we measured the frequency and distribution of molecular abnormalities of EGFR as well as the aberrant promoter methylations of BRCA1, MGMT, MLH1, and RASSF1A in Vietnamese lung adenocarcinomas. We investigated the association between genetic and epigenetic alteration, and between each abnormality with clinicopathologic parameters. Somatic EGFR mutation that was found in 49/139 (35.3%) lung adenocarcinomas showed a significant association with young age, female gender, and non-smokers. EGFR overexpression was identified in 82 tumors (59.0%) and statistical relationships with EGFR or BRCA1 methylation but not EGFR mutation. In addition, EGFR, BRCA1, MGMT, MLH1, and RASSF1A methylations were found in 33 (23.7%), 41 (29.5%), 46 (33.1%), 28 (20.1%), and 41 (29.5%) cases of a total of 139 lung adenocarcinomas, respectively. The RASSF1A methylation was found to be linked to the smoking habit. Methylations in MGMT and RASSF1A were also found to correlate with metastasis status. Furthermore, the distribution of EGFR mutation and that of BRCA1, MGMT or RASSF1A methylation were significantly exclusive in lung adenocarcinomas. The main finding of our study demonstrate that epigenetic abnormalities might play a critical role for the lung tumorigenesis in patients with smoking history and metastasis, and partly affect the predictive value of EGFR mutations through blocking expression due to promoter EGFR hypermethylation. Mutually exclusive distribution of genetic and epigenetic alterations reflects differently biological characteristics in the etiology of lung adenocarcinomas. 相似文献
17.
18.
19.
20.
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