全文获取类型
收费全文 | 4788篇 |
免费 | 458篇 |
国内免费 | 41篇 |
专业分类
耳鼻咽喉 | 85篇 |
儿科学 | 151篇 |
妇产科学 | 98篇 |
基础医学 | 630篇 |
口腔科学 | 97篇 |
临床医学 | 656篇 |
内科学 | 781篇 |
皮肤病学 | 72篇 |
神经病学 | 343篇 |
特种医学 | 389篇 |
外科学 | 584篇 |
综合类 | 70篇 |
现状与发展 | 1篇 |
一般理论 | 1篇 |
预防医学 | 540篇 |
眼科学 | 91篇 |
药学 | 387篇 |
肿瘤学 | 311篇 |
出版年
2022年 | 32篇 |
2021年 | 59篇 |
2020年 | 29篇 |
2019年 | 56篇 |
2018年 | 83篇 |
2017年 | 43篇 |
2016年 | 61篇 |
2015年 | 80篇 |
2014年 | 109篇 |
2013年 | 146篇 |
2012年 | 213篇 |
2011年 | 199篇 |
2010年 | 154篇 |
2009年 | 126篇 |
2008年 | 204篇 |
2007年 | 225篇 |
2006年 | 261篇 |
2005年 | 181篇 |
2004年 | 167篇 |
2003年 | 173篇 |
2002年 | 169篇 |
2001年 | 158篇 |
2000年 | 147篇 |
1999年 | 123篇 |
1998年 | 111篇 |
1997年 | 89篇 |
1996年 | 122篇 |
1995年 | 90篇 |
1994年 | 68篇 |
1993年 | 79篇 |
1992年 | 104篇 |
1991年 | 86篇 |
1990年 | 107篇 |
1989年 | 109篇 |
1988年 | 121篇 |
1987年 | 86篇 |
1986年 | 80篇 |
1985年 | 88篇 |
1984年 | 62篇 |
1983年 | 41篇 |
1982年 | 46篇 |
1981年 | 35篇 |
1980年 | 30篇 |
1979年 | 48篇 |
1977年 | 36篇 |
1976年 | 34篇 |
1975年 | 37篇 |
1973年 | 34篇 |
1970年 | 30篇 |
1969年 | 25篇 |
排序方式: 共有5287条查询结果,搜索用时 15 毫秒
991.
T. K. Mittal S. F. S. Halpin M. W. Bourne M. D. Hourihan T. Perkins Y. Sun S. Tan 《Neuroradiology》1999,41(7):480-486
MRI is limited by movement artefact, even with current imagers, when examining a restless or claustrophobic patient. We prospectively
analysed the images of 92 patients produced by a single-shot fast spin-echo (SSFSE) pulse sequence and compared them with
conventional (FSE) and reduced-time fast spin-echo (RT-FSE) techniques, with regard to lesion detection and movement artefact
in brain imaging. Images obtained in each case were independently reviewed and scored for overall diagnosis, number of lesions
detected, and movement artefact. FSE showed 1217 lesions, RT-FSE 1137, and SSFSE 1044. This discrepancy arose mainly in patients
with multiple sclerosis or small-vessel disease, since with SSFSE we were less able to separate small, adjacent low-contrast
lesions than with FSE. Arbitrary movement scores were 36, 25 and zero respectively. There were, however, no clinically significant
differences in overall diagnosis between the three techniques. SSFSE thus proved a reliable, fast, accurate method for obtaining
T2-weighted images, and may be of particular use in the restless, claustrophobic or obtunded patient.
Received: 28 September 1998 Accepted: 12 December 1998 相似文献
992.
Fluroxypyr methyl ester (FPM) and the herbicide fluroxypyr methylheptyl ester (FPMH) are completely hydrolyzed during penetration through human and rat skin in vitro to the acid metabolite, fluroxypyr (FP) (). This article presents additional studies to determine the enzyme kinetics (K(m) and V(max)) of this ester hydrolysis, using crude rat whole-skin homogenate. Both FPM and FPMH were extensively metabolized in rat skin homogenates to the acid metabolite, FP. In no instance were any other metabolites detected. FPM was essentially hydrolyzed completely within 1 h. In FPMH incubations, there was still parent ester present after 24 h at all concentrations tested. The kinetics of hydrolysis of the two esters were different: V(max) was approximately 3-fold greater for FPM than FPMH (1400 and 490 micromol FP/min/g of tissue, respectively); however, K(m) values were very similar, 251 and 256 microM, respectively. Preliminary inhibitory studies suggest that FPM and FPMH are hydrolyzed by a carboxylesterase, because this reaction was inhibited by bis-p-nitrophenyl phosphate. Mercuric chloride (an inhibitor of A-esterase and arylesterase) and eserine (a cholinesterase inhibitor) had no inhibitory effect on the hydrolysis of FPM or FPMH. Taken together with the data presented by, it can be concluded that no parent ester will pass through the skin in vivo, only the metabolite, FP. Therefore, first pass metabolism will be complete before these compounds reach the systemic circulation. 相似文献
993.
胃癌病因:人N-亚硝酰胺暴露 总被引:19,自引:6,他引:13
胃癌死亡率居我国恶性肿瘤之首.其危险因素包括:①化学因素,如胃内合成的亚硝基化合物(NOC)和高盐饮食;②生物因素,如幽门螺杆菌感染和摄入生物毒素;③营养因素,如维生素C、硒和其他抗氧化剂等缺乏.NOC的胺类前体物和亚硝化剂(亚硝酸根和各种氧化氮)广泛存在于人体内外环境中,研究发现NOC暴露,可能与上消化道肿瘤的发生有关.高盐饮食和某些微量营养素缺乏,则能够增强NOC的致癌性.幽门螺杆菌感染与胃腺癌发生的关系尚未确定,但与胃粘膜相关性淋巴样组织淋巴瘤(MALT)的存在关系密切,机制不明.已知感染该菌能引发萎缩性胃炎和胃酸缺乏,间接促进NOC胃内合成.可见,NOC是多种胃癌高危因素的作用靶点,是证据最多的诱发胃癌因素. 相似文献
994.
995.
996.
Teresa M. Damush Morris Weinberger Daniel O. Clark William M. Tierney Jaya K. Rao Susan M. Perkins Kelly Verel 《Arthritis care & research》2002,47(4):372-379
Objectives
To describe the rationale and design of a self‐management program for low‐income, urban, primary care patients with acute low back pain. Issues related to recruitment and protocol delivery, and attendance patterns and predictors of program attendance are described.Methods
Two hundred eleven adult patients (73% female; 60% African American) were recruited from primary care neighborhood health centers. Focus groups were conducted for program development, and participants then completed a baseline interview and were randomized into groups receiving either usual care or a self‐management intervention.Results
Twenty‐nine percent of the intervention group attended the self‐management class. Significant predictors of attendance included being older, reporting less income, and not working for pay. Attendees did not differ from nonattendees on back pain severity, symptoms, health‐related quality of life, self‐management processes, or satisfaction with care.Conclusion
Effective minimal‐contact behavioral interventions are needed to reach larger portions of the patient population.997.
Alon Abraham Carolina Barnett Leif E. Lovblom Bruce A. Perkins Vera Bril Hans D. Katzberg 《Clinical neurophysiology》2018,129(1):122-126
Objectives
To explore the correlations between different muscle cramp characteristics including cramp frequency and severity and clinical and large and small nerve fiber measures in patients with diabetes type 1 (DM 1) and 2 (DM 2).Methods
Prospective cross sectional study of healthy controls and patients with DM 1 and DM 2 recruited between April 2009 and November 2012. Participants underwent clinical evaluation and large and small nerve fiber studies, and the frequency and correlations of muscle cramps were explored.Results
37 controls, 51 patients with DM 1, and 69 patients with DM 2 were studied. Muscle cramps were the most frequent symptom captured by the Toronto Clinical Neuropathy Score (TCNS) in all groups, up to 78% in patients with DM 2. In patients with DM 1, but not DM 2, muscle cramp frequency and severity were correlated with clinical (TCNS) and both large (electrophysiology and vibration perception thresholds) and small nerve fiber measures.Conclusions
Muscle cramps are frequent in diabetes and are correlated with clinical and both small and large nerve fiber measures in DM 1, suggesting that their origin and propagation might extend beyond the motor nerve.Significance
Muscle cramps correlate with nerve fiber measures in DM 1. 相似文献998.
999.
Jon Davis Perkins Maiss Ajeeb Lina Fadel Ghassan Saleh 《Social psychiatry and psychiatric epidemiology》2018,53(11):1231-1239
Purpose
Studies show that conflict can negatively affect psychological health. The Syrian crisis is 8 years old and yet little is known about the impact of the conflict on the well-being of Syrians who remain. This gap was addressed by conducting an empirical study on the mental health burden of Syrian children in two areas of the country.Methods
492 children between 8 and 15 years were randomly selected from schools in Damascus and Latakia. The incidence of psychological disorder symptoms was measured using self-report screening instruments, the Children’s Revised Impact of Event Scale (CRIES-8) and the Revised Children’s Anxiety and Depression Scale (RCADS-25). Simultaneously, sociodemographic and traumatic event information was collected. Binary logistic regression was used to identify factors that influence the development of post-traumatic stress disorder (PTSD) symptoms.Results
In our sample, 50.2% of students were internally displaced and 32.1% reported a negative experience. 60.5% of those tested had at least one probable psychological disorder with PTSD the most common (35.1%), followed by depression (32.0%), and anxiety (29.5%). Binary logistic regression indicated that PTSD symptoms were predicted by: living in Damascus [odds ratio (OR) 2.36, 95% confidence interval (CI) 1.51–3.69], being female (1.54, 1.02–2.34), having depression and anxiety (2.55, 1.48–4.40), and the negative experiences; displacement and daily warzone exposure (1.84, 1.02–3.30 and 2.67, 1.08–6.60).Conclusions
Syrian children are experiencing traumatic events and war-associated daily stresses that are hugely impacting psychological well-being. Our data offer guidance for mental health providers regarding risk factors and highlights the use of the school system to reach suffering children.1000.
Stewart Jessica K. Perkins Scott S. Kim Charles Y. 《Cardiovascular and interventional radiology》2017,40(9):1447-1453
CardioVascular and Interventional Radiology - The purpose of this study was to assess the technical feasibility of ultrasound-guided endovascular creation of a percutaneous extraluminal arterial... 相似文献