全文获取类型
收费全文 | 4963篇 |
免费 | 312篇 |
国内免费 | 17篇 |
专业分类
耳鼻咽喉 | 59篇 |
儿科学 | 177篇 |
妇产科学 | 78篇 |
基础医学 | 705篇 |
口腔科学 | 224篇 |
临床医学 | 450篇 |
内科学 | 1023篇 |
皮肤病学 | 117篇 |
神经病学 | 486篇 |
特种医学 | 318篇 |
外科学 | 469篇 |
综合类 | 40篇 |
一般理论 | 1篇 |
预防医学 | 347篇 |
眼科学 | 43篇 |
药学 | 412篇 |
1篇 | |
中国医学 | 9篇 |
肿瘤学 | 333篇 |
出版年
2021年 | 62篇 |
2020年 | 52篇 |
2019年 | 52篇 |
2018年 | 66篇 |
2017年 | 49篇 |
2016年 | 64篇 |
2015年 | 58篇 |
2014年 | 75篇 |
2013年 | 145篇 |
2012年 | 206篇 |
2011年 | 205篇 |
2010年 | 117篇 |
2009年 | 113篇 |
2008年 | 218篇 |
2007年 | 201篇 |
2006年 | 233篇 |
2005年 | 214篇 |
2004年 | 201篇 |
2003年 | 186篇 |
2002年 | 180篇 |
2001年 | 164篇 |
2000年 | 145篇 |
1999年 | 133篇 |
1998年 | 86篇 |
1997年 | 76篇 |
1996年 | 75篇 |
1995年 | 81篇 |
1994年 | 70篇 |
1993年 | 73篇 |
1992年 | 138篇 |
1991年 | 116篇 |
1990年 | 106篇 |
1989年 | 145篇 |
1988年 | 93篇 |
1987年 | 110篇 |
1986年 | 118篇 |
1985年 | 116篇 |
1984年 | 81篇 |
1983年 | 68篇 |
1982年 | 56篇 |
1981年 | 45篇 |
1980年 | 43篇 |
1979年 | 41篇 |
1978年 | 51篇 |
1977年 | 44篇 |
1976年 | 31篇 |
1975年 | 37篇 |
1974年 | 31篇 |
1973年 | 20篇 |
1972年 | 27篇 |
排序方式: 共有5292条查询结果,搜索用时 0 毫秒
101.
The chronic (2-yr) inhalation toxicity of 1,3-butadiene (BD), a chemical used in large quantities to make rubber and plastics, differs greatly between mice and rats. Mice develop lung tumors after exposures to concentrations as low as 6.25 ppm, whereas rats develop mammary tumors only after exposures to 1000-8000 ppm BD. Extensive research has been carried out to determine where humans fit into this susceptibility range. Species differences in rates of metabolism of BD have been noted, but inconsistencies in metabolism data from different laboratories and some problems in the fit of physiologically based pharmacokinetic (PBPK) models with experimental data have left uncertainties. The experiments reported here are intended to clarify the issue of human metabolism of BD and to determine if metabolism of BD in cynomolgus monkeys is similar enough to metabolism in humans to use in vivo data from monkeys for PBPK modeling. The results indicate that for the reactions studied (oxidation of BD to the mono- and diepoxide), BD is metabolized substantially the same in monkey and human hepatic microsomes. The human metabolism data agreed with that reported earlier when the in vitro metabolism of BD was studied at low BD concentrations. Finally, BD at high concentrations was found to inhibit the further oxidation of its metabolite, the monoepoxide. Incorporation of this information on the competition between BD and its first oxidation product for CYP2E1 should improve the fit of PBPK models. 相似文献
102.
Shulin Wu Sharron X. Lin Gregory J. Wirth Min Lu Jian Lu Alexander O. Subtelny Zongwei Wang Douglas M. Dahl Aria F. Olumi Chin-Lee Wu 《Clinical genitourinary cancer》2019,17(1):e44-e52
Objective
To assess the impact of focality and location of positive surgical margins (PSM) on long-term outcomes after radical prostatectomy (RP) for prostate cancer (PCa), including biochemical recurrence (BCR), metastasis and overall mortality.Patients and Methods
From a total of 2796 cases of RP between 1993 and 2007 in our single hospital, 476 cases with PSMs were identified and included in this study. PSM location was categorized into apex, peripheral, and bladder neck. Survival was estimated using the Kaplan-Meier method. Cox proportional hazard regression models were used to analyze the impact of PSM focality and location status on oncologic survival.Results
Of these 476 cases with PSMs, 335 (70.4%) cases were with single focal (sF) PSMs and 141 (29.6%) cases were with multifocal (mF) PSMs. Furthermore, 406 (85.3%) cases were found to have single location (sL) PSMs, and 70 (14.7%) cases were with multilocation (mL) PSMs. The median follow-up was 12.9 years. mF-PSMs and mL-PSMs showed significant impact on increased BCR risk on univariate analysis, and mL-PSMs remained significant on multivariate analysis (P = .048). Furthermore, the combination of multifocality and multilocation showed added prognostic value on predicting BCR-free survival, but not on metastasis-free survival or overall survival.Conclusion
The presence of mF-PSMs and mL-PSMs, and especially the combination of both, demonstrated significant impact on BCR prognosis. Patients with apex sLsF-PSMs were less likely to have BCR when compared with all those with non-apex sLsF-PSMs. These results should be considered when evaluating patients for adjuvant therapy. 相似文献103.
104.
105.
106.
Thomas M. Olino Dana L. McMakin Ronald E. Dahl Neal D. Ryan Jennifer S. Silk Boris Birmaher David A. Axelson Erika E. Forbes 《Psychiatry Research: Neuroimaging》2011,194(3):393-395
Major Depressive Disorder (MDD) in adolescents is characterized by alterations in positive emotions and reward processing. Recent investigations using functional magnetic resonance imaging (fMRI) find depression-related differences in reward anticipation. However, it is unknown whether feedback influences subsequent reward anticipation, which may highlight the context of reward processing. Ten youth with MDD and 16 youth with no history of MDD completed an fMRI assessment using a reward task. Reward anticipation was indexed by blood oxygen level dependent signal change in the striatum following winning, losing, non-winning, and non-losing outcomes. A significant interaction between diagnostic status and outcome condition predicted reward anticipation in the caudate. Decomposition of the interaction indicated that following winning outcomes, depressed youth demonstrated reduced reward anticipation relative to healthy youth. However, no significant differences between depressed and healthy youth were found after other outcomes. Reward anticipation is altered following winning outcomes. This finding has implications for understanding the developmental pathophysiology of MDD and suggests specific contexts where altered motivational system functioning may play a role in maintaining depression. 相似文献
107.
T. F. Aarre A. A. Dahl J. B. Johansen I. Kjønniksen D. Neckelmann 《Nordic journal of psychiatry》2013,67(3):227-232
Repetitive transcranial magnetic stimulation (rTMS) is a novel treatment in psychiatry. We reviewed all published evidence on the efficacy of this treatment option in depressive disorders. An extensive electronic and manual search for eligible research reports identified only 12 studies that met the predetermined criteria for inclusion. rTMS was administered differently in most studies, and patient characteristics varied widely. A formal meta-analysis of the studies was thus not possible. Instead, we conducted a qualitative evaluation of the included studies. The antidepressive efficacy was not consistent, and where efficacy was demonstrated, it was modest in most studies. Some patients had good but transient responses to rTMS. Treatment gains were not maintained beyond the treatment period. Comparisons with electroconvulsive therapy (ECT) indicated the superiority of ECT. More, larger and more carefully designed studies are needed to demonstrate convincingly a clinically relevant effect of rTMS. We conclude that there is insufficient evidence for rTMS as a valid treatment for depression at present. 相似文献
108.
109.
Ortiz-Alvarez O; Cabral D; Prendiville JS; Stringer D; Petty RE; Malleson PN 《Rheumatology (Oxford, England)》1997,36(2):280-284
Two children are reported in whom intestinal pseudo-obstruction was the
initial manifestation of systemic sclerosis. Gastrointestinal symptoms and
skin changes resolved or improved in both children following treatment with
prednisone and penicillamine (case 1) or methotrexate (case 2), although
radiological changes of the gastrointestinal tract persisted at 3 and 2 yr
of follow-up, respectively.
相似文献
110.
Faecal calprotectin and lactoferrin as markers of acute radiation proctitis: a pilot study of eight stool markers 总被引:4,自引:0,他引:4
Larsen A Hovdenak N Karlsdottir A Wentzel-Larsen T Dahl O Fagerhol MK 《Scandinavian journal of gastroenterology》2004,39(11):1113-1118
BACKGROUND: Non-invasive diagnostic tools to evaluate the severity of acute, radiation-induced proctitis are not readily available. The faecal excretion of eight markers of gut inflammation was therefore examined. Five proteins and three lipid derivates were analysed in sequential stool samples taken before and during radiation therapy. METHODS: Stool samples from 15 patients with prostate cancer scheduled for radiation therapy were examined. Pretreatment and in-treatment samples (2nd and 6th weeks) were measured by enzyme-linked immunosorbent assay (ELISA) (calprotectin, lactoferrin, transferrin, leukotriene B4, prostaglandin E2, thromboxane B2 and TNF alpha) or nephelometry (alpha 1-antitrypsin). RESULTS: Calprotectin and lactoferrin concentrations increased significantly during radiation treatment (P = 0.0005 and P = 0.019). Transferrin was detected in only 9 out of 45 samples. There were no changes in tumour necrosis factor alpha (TNF alpha), leukotriene B4, prostaglandin E2 and thromboxane B2 during treatment. alpha 1-antitrypsin could not be detected in any sample. CONCLUSIONS: This study indicates that faecal calprotectin and lactoferrin concentrations could be markers of acute, radiation-induced proctitis. Patient compliance and stability of the markers make this a promising method for clinical research. Eicosanoids could be measured in stool samples, but the concentrations did not increase with increasing radiation dose. 相似文献