全文获取类型
收费全文 | 2645篇 |
免费 | 111篇 |
国内免费 | 15篇 |
专业分类
耳鼻咽喉 | 15篇 |
儿科学 | 225篇 |
妇产科学 | 51篇 |
基础医学 | 217篇 |
口腔科学 | 63篇 |
临床医学 | 209篇 |
内科学 | 512篇 |
皮肤病学 | 26篇 |
神经病学 | 89篇 |
特种医学 | 64篇 |
外科学 | 697篇 |
综合类 | 61篇 |
一般理论 | 1篇 |
预防医学 | 169篇 |
眼科学 | 69篇 |
药学 | 164篇 |
中国医学 | 7篇 |
肿瘤学 | 132篇 |
出版年
2023年 | 22篇 |
2022年 | 72篇 |
2021年 | 98篇 |
2020年 | 67篇 |
2019年 | 72篇 |
2018年 | 83篇 |
2017年 | 53篇 |
2016年 | 92篇 |
2015年 | 79篇 |
2014年 | 113篇 |
2013年 | 128篇 |
2012年 | 195篇 |
2011年 | 234篇 |
2010年 | 93篇 |
2009年 | 114篇 |
2008年 | 152篇 |
2007年 | 136篇 |
2006年 | 98篇 |
2005年 | 108篇 |
2004年 | 100篇 |
2003年 | 89篇 |
2002年 | 72篇 |
2001年 | 55篇 |
2000年 | 37篇 |
1999年 | 36篇 |
1998年 | 15篇 |
1996年 | 10篇 |
1995年 | 7篇 |
1994年 | 12篇 |
1992年 | 24篇 |
1991年 | 19篇 |
1990年 | 11篇 |
1989年 | 25篇 |
1988年 | 22篇 |
1987年 | 18篇 |
1986年 | 13篇 |
1985年 | 16篇 |
1984年 | 23篇 |
1983年 | 11篇 |
1982年 | 7篇 |
1981年 | 9篇 |
1980年 | 9篇 |
1979年 | 14篇 |
1977年 | 14篇 |
1976年 | 7篇 |
1973年 | 9篇 |
1972年 | 14篇 |
1970年 | 6篇 |
1969年 | 10篇 |
1968年 | 6篇 |
排序方式: 共有2771条查询结果,搜索用时 0 毫秒
71.
72.
Haroon I. Sheikh Katie R. Kryski Heather J. Smith Lea R. Dougherty Daniel N. Klein Sara J. Bufferd Shiva M. Singh Elizabeth P. Hayden 《American journal of medical genetics. Part B, Neuropsychiatric genetics》2013,162(3):245-252
Catechol‐O‐Methyltransferase (COMT) is a critical regulator of catecholamine levels in the brain. A functional polymorphism of the COMT gene, val158met, has been linked to internalizing symptoms (i.e., depression and anxiety) in adolescents and adults. We extended this research by investigating whether the val158met polymorphism was associated with childhood symptoms of depression and anxiety in two independent samples of young children (Ns = 476 and 409). In both samples, preschool‐aged children were genotyped for the COMT val158met polymorphism. Symptoms of psychopathology were assessed via parent interviews and primary caregiver reports. In both samples, children homozygous for the val allele had higher levels of depressive symptoms compared to children with at least one copy of the met allele. Our findings extend previous research in older participants by showing links between the COMT val158met polymorphism and internalizing symptoms in early childhood. © 2013 Wiley Periodicals, Inc. 相似文献
73.
74.
AIM: To compare the non-invasive tear film break-up time (NIBUT), tear break up time (TBUT), basal tear secretion (BTS) and blink rate in four ethnic groups: Malay, Chinese, Indian and Nigerian.
METHODS: Totally 120 healthy (61 males and 59 females) subjects (without dry eye symptoms and ocular surface disorder) with the age 20 to 39 years were recruited; 30 were Malays, 30 were Chinese, 31 were Indians and 29 were Nigerians. Based on McMonnies questionnaire and clinical examination, normal subjects were selected. NIBUT, TBUT, BTS were assessed in only one eye (right) of each subject and blink rate was also assessed.
RESULTS: There was significant difference in the NIBUT, TBUT, BTS and blink rate among 4 different ethnic groups (P=0.018, 0.001, 0.011, and 0.004 respectively). No statistically significant difference of NIBUT, TBUT, BTS and blink rate was found between the genders among different ethnic groups. Indian had higher median for NIBUT (10±6s), TBUT (7±5s) and BTS (20±20 mm) than other races. Chinese had lower median for NIBUT (7.5±4s) and TBUT (4±2s) while Malay had for BTS (9.5±16 mm) among the groups. There was no significant correlation of blink rate with NIBUT (r=-0.119, P=0.195), TBUT (r=-0.086, P=0.352), and BTS (r=-0.123, P=0.180) respectively.
CONCLUSION: The tear-film measurement values are variability in four ethnic groups. 相似文献
75.
Sonal Bhandari Sravani Sana Vandana Lahoti Ramya Tokala Nagula Shankaraiah 《RSC advances》2020,10(27):16101
Herein, we report a facile tandem approach for the synthesis of both spiro-oxindole-fused pyrroloindolines and benzofurano-pyrrolidines via a Lewis acid-catalyzed domino ring-opening with concomitant ring annulation using activated spiro-aziridines and heteroarenes. This method offers a new class of novel spiro-fused polycyclic pyrrolidines in a one-pot and sustainable manner with good yields and high diastereoselectivity. In addition, the structure of 3d was confirmed by single X-ray crystallography analysis.Herein, we report a facile tandem approach for the synthesis of both spiro-oxindole-fused pyrroloindolines and benzofurano-pyrrolidines via a Lewis acid-catalyzed domino ring-opening annulation using activated spiro-aziridines and heteroarenes. 相似文献
76.
77.
78.
Shiva Alavi Ehsan Abolhasani Mohammadali Nilforoushzadeh 《Lasers in medical science》2016,31(3):481-484
The effects of alexandrite laser (AL) on skin parameters such as melanin content, skin layer depth, elasticity, and density have not been investigated through biometric methods. We aim to assess the effect of AL on the skin parameters through biometric devices to determine whether it has positive effects on treated region. In this pretest-posttest study, we recruited patients who attended Laser Clinic of Skin and Stem Cell Research Center, Tehran University of Medical Sciences, Tehran, Iran, from January through December 2014. Patients had to be free of any dermatologic conditions and lesion at the site of treatment or any contraindication to laser therapy. Baseline measurements were performed and patients received four sessions of AL therapy (spot size, 12 mm; fluence, 12 J/cm2; and pulse width, 5 Hz) with 4-week intervals. Four weeks after the last treatment session, the same parameters were assessed that included skin color, transepidermal water loss (TEWL), dermis and epidermis density and depth (through skin ultrasonography), melanin content, erythema intensity, and skin elasticity. Biometric parameters of 33 patients (27 females [81.8 %]), with mean (SD) age of 35.7 (9.5)?years were evaluated. The mean percent changes of skin parameters were as follows: skin color, 5.88 % through Visioface and by 56.8 % through Colorimeter devices (became lighter); melanin content, ?15.95 %; TEWL, ?2.96 %; elasticity, +14.88 %; dermis depth ?19.01 %; and dermis density, +1580.11 % (P?<?0.001 for changes in each parameter). AL could decrease melanin content of the skin and make the skin thinner while it could increase elasticity and density of epidermis and dermis, which might indicate increased collagen content of skin. 相似文献
79.
Jeremy S. Somerson Katherine C. Bartush Jeffrey B. Shroff Mohit Bhandari Boris A. Zelle 《International orthopaedics》2016,40(11):2213-2219
Purpose
The rate of patients lost to follow-up may contribute to bias in randomized controlled trials (RCTs).Methods
We systematically reviewed orthopaedic RCTs from 2008 to 2011, including 559 RCTs with 131,836 enrolled subjects. The loss to follow-up rates and minimum follow-up times were recorded for each trial. Orthopaedic subspecialty, country of origin, number of enrolled patients, patient age, follow-up strategy, and funding type were also recorded.Results
Loss to follow-up was not reported in 111 of these studies (20 %). Mean loss to follow-up was 10.4 %. No orthopaedic subspecialty demonstrated significantly different follow-up rates. Remote follow-up strategies did not reduce the loss to follow-up rate. Studies with a minimum follow-up length of three years showed significantly higher loss to follow-up rates compared with studies with shorter minimum follow-up time (14.8 % versus 9.8 %, p?=?0.01). Studies performed in the United States had a significantly higher rate of loss to follow-up compared with non-United States studies (13.8 % versus 9.4 %; p?=?0.01).Conclusions
Loss to follow-up rates in published orthopaedic randomized controlled trials is overall relatively low. A substantial portion of publications does not adequately report follow-up data. Studies performed in the United States and studies with longer follow-up periods seem to be at higher risk for loss to follow-up.80.