全文获取类型
收费全文 | 16044篇 |
免费 | 1075篇 |
国内免费 | 25篇 |
专业分类
耳鼻咽喉 | 233篇 |
儿科学 | 614篇 |
妇产科学 | 391篇 |
基础医学 | 1871篇 |
口腔科学 | 168篇 |
临床医学 | 2328篇 |
内科学 | 2863篇 |
皮肤病学 | 164篇 |
神经病学 | 1806篇 |
特种医学 | 372篇 |
外科学 | 1439篇 |
综合类 | 168篇 |
一般理论 | 18篇 |
预防医学 | 2245篇 |
眼科学 | 331篇 |
药学 | 956篇 |
中国医学 | 12篇 |
肿瘤学 | 1165篇 |
出版年
2024年 | 21篇 |
2023年 | 143篇 |
2022年 | 233篇 |
2021年 | 546篇 |
2020年 | 331篇 |
2019年 | 507篇 |
2018年 | 527篇 |
2017年 | 392篇 |
2016年 | 416篇 |
2015年 | 427篇 |
2014年 | 593篇 |
2013年 | 897篇 |
2012年 | 1242篇 |
2011年 | 1377篇 |
2010年 | 703篇 |
2009年 | 612篇 |
2008年 | 1056篇 |
2007年 | 1103篇 |
2006年 | 1043篇 |
2005年 | 931篇 |
2004年 | 833篇 |
2003年 | 799篇 |
2002年 | 689篇 |
2001年 | 111篇 |
2000年 | 87篇 |
1999年 | 103篇 |
1998年 | 136篇 |
1997年 | 98篇 |
1996年 | 75篇 |
1995年 | 77篇 |
1994年 | 77篇 |
1993年 | 62篇 |
1992年 | 69篇 |
1991年 | 59篇 |
1990年 | 52篇 |
1989年 | 46篇 |
1988年 | 45篇 |
1987年 | 46篇 |
1986年 | 52篇 |
1985年 | 57篇 |
1984年 | 46篇 |
1983年 | 34篇 |
1982年 | 37篇 |
1981年 | 42篇 |
1980年 | 40篇 |
1979年 | 33篇 |
1978年 | 23篇 |
1976年 | 19篇 |
1975年 | 21篇 |
1972年 | 19篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
Zenab Amin Ralitza Gueorguieva Angela Cappiello Kathryn A Czarkowski Stephanie Stiklus George M Anderson Frederick Naftolin C Neill Epperson 《Neuropsychopharmacology》2006,31(11):2489-2497
Despite an abundance of data in animals, there is little research in humans regarding how estrogen and serotonin (5-HT) may interact to influence cognition. Through the use of estrogen treatment (ET) and tryptophan depletion (TRP-D) in a within-subject design involving healthy menopausal women, we have manipulated both estrogen and 5-HT in order to evaluate their individual and joint effects. Although neither manipulation influenced visuospatial learning, a significant interaction suggested that estrogen exerted a protective effect on verbal memory, such that TRP-D impaired performance to a greater extent before the administration of ET. In consonance with this finding, ET was associated with a small, but positive mood effect on the day following active TRP-D. In addition, ET significantly improved letter-cued verbal fluency with and without TRP-D. Finally, time since last menstrual period was significantly associated with verbal memory scores, such that longer length of hypogonadism resulted in decreased verbal memory performance. These data support the interaction of estrogen and 5-HT in nonreproductive behavior in humans as well as highlight the role of ovarian steroids in cognition. 相似文献
42.
Sylvie Naar-King Kathryn Wright Jeffrey T Parsons Maureen Frey Thomas Templin Phebe Lam Debra Murphy 《AIDS education and prevention》2006,18(1):1-11
This study piloted a brief individual motivational intervention targeting multiple health risk behaviors in HIV-positive youth aged 16-25. Interviews about sexual behavior and substance use and viral load testing were obtained from 51 HIV-positive youth at baseline and post intervention. Youth were randomized to receive a four-session motivational enhancement intervention (N = 25) or to a wait-list control (N = 26). Of the eligible youth approached, 88% agreed to participate, and 80% percent of participants completed at least three of four sessions. The treatment group showed significantly greater reductions in unprotected sex acts and in viral load compared with controls. Although change scores for substance use were not significantly different between the two groups, paired t tests demonstrated that reductions in alcohol use and marijuana use were significant for the treatment group at the trend level. There were no significant differences in substance use from baseline to posttest for the control group. Findings demonstrate the potential of a brief motivational enhancement intervention to improve health risk behaviors in HIV-positive youth. Larger randomized clinical trials are warranted. Resources required for retention should not be underestimated. 相似文献
43.
Rupak Mukherjee Preecha Laohakunakorn M. Charles Welzig Kathryn S. Cowart J. Philip Saul 《Journal of interventional cardiac electrophysiology》2003,9(3):309-315
Background: Radiofrequency (RF) lesion size in vitro is positively correlated with applied power and catheter tip temperature. However, the relation between RF lesion size, power, and tip temperature in vivo remains unclear. We hypothesized that due to flow, anatomy and tip contact effects in vivo, increased tip temperature would be inversely related to applied power and RF lesion size.
Methods: RF lesions were created on the endocardium of 16 pigs using 5, 6, and 7 Fr catheters. The ablation generator was set to achieve a temperature of 70°C. RF lesions were created in different regions of the heart so as to encompass a wide range of blood flow and catheter movement conditions. RF lesions were measured acutely (DIMEN, mm) and correlated with average power applied (POWER, W), and average tip temperature (TEMP, °C). The POWER and TEMP relation was also examined.
Results: For TEMPs below 55°C, the power output from the generator was typically maximized at 50 W. At TEMPs above 55°C, POWER decreased exponentially with increasing TEMP {POWER = 50 – exp(-((41-TEMP)/7)), r = 0.98, p < 0.05}. Further, DIMEN tended to be inversely related to TEMP (Slope: –0.07 ± 0.04, r = –0.15, p = 0.07); but, was positively related to POWER (Slope: 0.04 ± 0.02, r = 0.23, p < 0.05). These relations varied by tip size and estimated local blood flow characteristics.
Conclusion: In vivo, variable tissue contact and flow yield DIMEN-POWER-TEMP relations opposite to those found in vitro. These counterintuitive results suggest that maximum in vivo RF lesion size is achieved when power is maximized at tip temperatures between 50 and 60°C. 相似文献
44.
Adel M. Mansour Robert W. Frenck Jr. Toni Darville Isabelle A. Nakhla Thomas F. Wierzba Yehia Sultan Magdy I. Bassiouny Kathryn McCarthy Richard F. Jacobs 《Clinical and Vaccine Immunology : CVI》2005,12(2):363-365
Cerebrospinal fluid gamma interferon (IFN-γ) and interleukin-10 levels in 39 patients with tuberculous meningitis were serially measured. Cytokine levels did not predict intracranial granuloma (IG) development, but IFN-γ levels in the top quartile after 1 month of therapy were highly associated (odds ratio = 18) with detection of an IG by computed tomography scanning. 相似文献
45.
46.
Background
Persisting neck pain is common in society. It has been reported that the prevalence of neck pain in office workers is much higher than in the general population. The costs to the worker, employer and society associated with work-related neck pain are known to be considerable and are escalating. The factors that place office workers at greater risk of developing neck pain are not understood. The aim of this study is to investigate the incidence and risk factors of work-related neck pain in Australian office workers. 相似文献47.
48.
B. H. Green J. R. M. Copeland M. E. Dewey V. Sharma I. A. Davidson 《International journal of geriatric psychiatry》1994,9(10):789-795
The Liverpool Continuing Health in the Community Study has followed up 1070 elderly community subjects over 6 years. In the first year 123 subjects had case-level depression. Three years later 49 (39.8%) of the previously depressed were recovered, 33 (26.8%) were depressed, 16 (13%) were not available for interview and 25 (20.3%) were dead. This study looks at factors associated with the 3-year outcome of patients who were depressed at year 0. Two outcome groups that were compared were a recovered depression group and a recurrent/persistent depression group. The factors that were significantly associated with a recurrence of depression (or persistent depression) at year 3 were bereavement of a close figure in the 6 months before interview, loneliness and life dissatisfaction at year 3. A variety of traditional risk factors for depression (including age, marital status, physical ill-health and incapacity) failed to attain significance in predicting recurrent or persistent depression. When combined, both recovered and recurrently depressed groups at year 3 had significantly higher levels of pain and a higher number of serious upsets in the past 6 months and 6 weeks compared to a compared to a control group. The depressed at year 0 were more likely to have entered more dependent forms of accommodation by year 3. 相似文献
49.
Managing recurrent urinary catheter blockage: problems, promises, and practicalities. 总被引:2,自引:0,他引:2
Kathryn Getliffe 《Journal of wound, ostomy, and continence nursing》2003,30(3):146-151
Long-term urinary catheterization is rarely completely free of complications, and encrustation by mineral salts leading to catheter blockage is common in around 40% to 50% of long-term catheterized patients. Recurrent blockage is a problem, which is both distressing to patients and caregivers and costly to health services in terms of time and resources. This article addresses the causes of recurrent urinary catheter blockage, proactive approaches to care, and the evidence for use of catheter maintenance solutions to reduce buildup of mineral deposits. 相似文献
50.
Carol A. Westall J. Margaret Woodhouse† Kathryn Saunders‡ Jane Evans‡ Belinda Hughes‡ 《Ophthalmic & physiological optics》1992,12(2):244-248
A preliminary study measured the contrast sensitivity function (CSF) in 30 children (aged 3 months-5 years). Preferential looking techniques were used to assess CSF to sine wave gratings displayed on one of two screens. To find a meaningful contrast sensitivity procedure we compared the results with a shorter procedure using an edge stimulus. The following problems were encountered: measuring the contrasts required to detect four or five different spatial frequencies took time, resulting in boredom and loss of attention in our subjects; there was poor correlation between CSF and edge detection; an interesting artefact resulted in a plateau rather than a low frequency fall-off in the CSF of five of the children greater than 30 months old. This artefact may have resulted from peripheral rather than central retinal responses and/or motion artefacts in the stimulus onset. A follow up study with 41 additional children aged 3-36 months limited the contrast testing to that of the spatial frequency corresponding to the peak of the CSF. The shortened procedure, plus a lot of encouragement, resulted in higher contrast sensitivities in all but the oldest age group and successful monocular contrast measurements. In order to avoid artefacts arising from peripheral vision, children were encouraged to look at each screen before responding. 相似文献