全文获取类型
收费全文 | 20362篇 |
免费 | 1278篇 |
国内免费 | 422篇 |
专业分类
耳鼻咽喉 | 315篇 |
儿科学 | 523篇 |
妇产科学 | 903篇 |
基础医学 | 2453篇 |
口腔科学 | 1092篇 |
临床医学 | 2152篇 |
内科学 | 1649篇 |
皮肤病学 | 129篇 |
神经病学 | 2715篇 |
特种医学 | 1253篇 |
外国民族医学 | 1篇 |
外科学 | 2344篇 |
综合类 | 2682篇 |
预防医学 | 756篇 |
眼科学 | 313篇 |
药学 | 1692篇 |
5篇 | |
中国医学 | 603篇 |
肿瘤学 | 482篇 |
出版年
2024年 | 35篇 |
2023年 | 242篇 |
2022年 | 439篇 |
2021年 | 670篇 |
2020年 | 615篇 |
2019年 | 580篇 |
2018年 | 577篇 |
2017年 | 588篇 |
2016年 | 632篇 |
2015年 | 676篇 |
2014年 | 1023篇 |
2013年 | 1246篇 |
2012年 | 1019篇 |
2011年 | 1202篇 |
2010年 | 1008篇 |
2009年 | 967篇 |
2008年 | 939篇 |
2007年 | 919篇 |
2006年 | 890篇 |
2005年 | 783篇 |
2004年 | 688篇 |
2003年 | 564篇 |
2002年 | 430篇 |
2001年 | 406篇 |
2000年 | 384篇 |
1999年 | 348篇 |
1998年 | 323篇 |
1997年 | 315篇 |
1996年 | 324篇 |
1995年 | 314篇 |
1994年 | 310篇 |
1993年 | 233篇 |
1992年 | 217篇 |
1991年 | 199篇 |
1990年 | 187篇 |
1989年 | 157篇 |
1988年 | 171篇 |
1987年 | 143篇 |
1986年 | 146篇 |
1985年 | 210篇 |
1984年 | 164篇 |
1983年 | 111篇 |
1982年 | 142篇 |
1981年 | 128篇 |
1980年 | 83篇 |
1979年 | 69篇 |
1978年 | 83篇 |
1977年 | 44篇 |
1976年 | 29篇 |
1973年 | 26篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
61.
Leo Sher Juan J Carballo Michael F Grunebaum Ainsley K Burke Gil Zalsman Yung-yu Huang J John Mann Maria A Oquendo 《Bipolar disorders》2006,8(5P2):543-550
Objectives: Bipolar disorder is a severe illness that is associated with suicidal behavior. A biological predictor of highly lethal suicide attempts in patients with bipolar disorder would be valuable. We hypothesized that cerebrospinal fluid (CSF) monoamine metabolite levels are related to lethality of suicide attempts in bipolar patients and examined the relation between CSF 5-hydroxyindolacetic acid (5-HIAA), homovanillic acid (HVA), and 3-methoxy-4-hydroxyphenylglycol (MHPG) levels and maximum lethality of suicide attempts at baseline and during a 2-year follow up.
Methods: Twenty-seven bipolar depressed patients participated in the study. Demographic and clinical parameters were examined and recorded. Lumbar punctures were performed and CSF 5-HIAA, HVA, and MHPG were assayed by high-performance liquid chromatography with electrochemical detection. Following discharge, patients were evaluated after 3 months, 1 year, and 2 years. Each follow-up interview included an in-depth assessment of suicidal behavior during the intervening time period.
Results: Six subjects made suicide attempts during the 2-year follow-up. Bipolar patients who attempted suicide during the follow-up period had higher aggression and hostility scale scores compared to bipolar subjects who did not make a suicide attempt during the follow-up period. CSF 5-HIAA, HVA, and MHPG levels were negatively correlated with the maximum lethality of suicide attempts during the 2-year follow-up period.
Conclusions: Our finding is the first observation that CSF monoamine metabolite levels may be predictors of lethality of suicide attempts in patients with bipolar disorder. Further studies are necessary to answer the question whether CSF monoamine metabolite levels are clinically useful biochemical predictors of highly lethal suicide attempts or completed suicides. 相似文献
Methods: Twenty-seven bipolar depressed patients participated in the study. Demographic and clinical parameters were examined and recorded. Lumbar punctures were performed and CSF 5-HIAA, HVA, and MHPG were assayed by high-performance liquid chromatography with electrochemical detection. Following discharge, patients were evaluated after 3 months, 1 year, and 2 years. Each follow-up interview included an in-depth assessment of suicidal behavior during the intervening time period.
Results: Six subjects made suicide attempts during the 2-year follow-up. Bipolar patients who attempted suicide during the follow-up period had higher aggression and hostility scale scores compared to bipolar subjects who did not make a suicide attempt during the follow-up period. CSF 5-HIAA, HVA, and MHPG levels were negatively correlated with the maximum lethality of suicide attempts during the 2-year follow-up period.
Conclusions: Our finding is the first observation that CSF monoamine metabolite levels may be predictors of lethality of suicide attempts in patients with bipolar disorder. Further studies are necessary to answer the question whether CSF monoamine metabolite levels are clinically useful biochemical predictors of highly lethal suicide attempts or completed suicides. 相似文献
62.
63.
64.
耳脑医用粘合剂是α-氰基丙烯酸正辛酯和α-氰基丙烯酸正丁酯及少量添加剂配伍而成的复合性医用粘合剂。应用此粘合剂粘合修补脑脊液漏27例,其中外伤性脑脊液鼻漏5例,经鼻蝶入路垂体瘤切除术脑脊液漏6例,开颅手术后手术切口脑脊液漏11例,脊膜膨出修补术后脑脊液漏5例。成功25例,成功率93%。应用此粘合剂修补脑脊液漏具有简便、迅速、有效的特点。 相似文献
65.
A 73-year-old woman presenting with persistent swelling of the right knee 30 months after total joint arthroplasty was found to have a Candida parapsilosis infection. Treatment with fluconazole resulted in full recovery. 相似文献
66.
A. Gregory Sorensen Andrew L. Tievsky Leif Ostergaard Robert M. Weisskoff Bruce R. Rosen 《Journal of magnetic resonance imaging : JMRI》1997,7(1):47-55
Contrast agents have greatly expanded the role of MR imaging (MRI) to allow assessment of physiologic, or “functional,” parameters. Although activation mapping generally does not require contrast agents, other forms of functional MRI, including mapping of cerebral hemodynamics (eg, perfusion imaging), are best done with the use of contrast agents. Serial echo planar images are obtained after bolus injection of lanthanide chelates. Application of susceptibility contrast physics and standard tracer kinetic principles permits generation of relative cerebral blood volume maps. Deconvolution of cerebral blood flow and mean transit time parameters is also possible within technical limitations. By using diffusion and perfusion pulse sequences, an imaging correlate to the ischemic penumbra can be identified. Functional MRI perfusion imaging of intraaxial tumors is analogous to positron emission tomography for delineation of metabolic activity, yet may be even more sensitive to neovascularity and possesses improved image quality. Clinical applications include biopsy site selection and postirradiation follow-up. Further improvements in data analysis and map generation techniques may improve diagnostic accuracy and utility. 相似文献
67.
本文报导了用40只白色短毛家兔所做的动物模拟失重实验,得出各脏器微血管通透性的动态反应曲线。并用微循环研究方法,分析了模拟失重时各脏器微血管功能状态与微血管通透性之间的关系;阐述了各脏器微循环功能变化特点;并对变化机理作了初步探讨。 相似文献
68.
69.
Danuta Wasserman Christer HellstrÖm Jerzy Wasserman Olof Beck Eva Andersson Marie Åsberg 《Archives of Suicide Research》1997,3(3):153-169
The aim of this study was to investigate markers of serotonin and immune function in suicidal patients. Cytotoxic activity of natural killer cells (NK) and CD16 lymphocytes were studied in 28 suicide attempters and 26 healthy controls, and related in patients to 5-hydroxyindoleacetic acid (5-HIAA) in cerebrospinal fluid (CSF). Patients with CSF 5-HIAA below the median had significantly lower NK cell activity than other patients. CD16 cell frequency was significantly lower in patients than in controls, and patients also tended to have lower NK cell cytotoxicity than healthy controls. There were no statistically significant correlations between 4-hydroxy-3methoxyphenyl glycol (HMPG), homovanillic acid (HVA), CSF cortisol and NK cell activity. The results support the hypothesis of compromised immune function in suicidal patients with evidence of disordered serotonin function. 相似文献
70.
Coronary vasomotion in patients with syndrome X: evaluation with positron emission tomography and parametric myocardial perfusion imaging 总被引:1,自引:1,他引:0
Joan G. Meeder Paul K. Blanksma Ernst E. van der Wall Antoon T. M. Willemsen Jan Pruim Rutger L. Anthonio Richard M. de Jong Willem Vaalburg Kong I. Lie 《European journal of nuclear medicine and molecular imaging》1997,24(5):530-537
The aim of this study was to elucidate further the causative mechanism of abnormal coronary vasomotion in patients with syndrome X. In patients with syndrome X, defined as angina pectoris and documented myocardial ischaemia during stress testing with normal findings at coronary angiography, abnormal coronary vasomotion of either the micro- or the macrocirculation has been suggested as the causative mechanism. Accordingly, we evaluated endothelial function, vasodilator reserve, and perfusion heterogeneity in these patients. Twenty-five patients with syndrome X (definitely normal coronary arteriogram, group A), 15 patients with minimal coronary artery disease (group B) and 21 healthy volunteers underwent [13N]ammonia positron emission tomography at rest, during cold pressor stimulation (endothelial function) and during dipyridamole stress testing (vasodilator reserve). Heterogeneity of myocardial perfusion was analysed by parametric polar mapping using a 480-segment model. In both patient groups, resting perfusion was increased compared to the normal subjects: group A, 127±31 ml·min–1·100 g–1; group B, 124±30 ml·min–1·100 g–1 normal subjects, 105±21 ml·min–1·100 g–1 (groups A and B vs normals,P<0.05). These differences were abolished after correction for rate-pressure product. During cold pressor stimulation, the perfusion responses (ratio of cold pressor perfusion to resting perfusion) were similar among the patients and the control subjects (group A, 1.20±0.23; group B, 1.24±0.22; normal subjects, 1.23±0.14). Likewise, during dipyridamole stress testing, perfusion responses were similar among the three groups (group A, 2.71±0.67; group B, 2.77±1.29; normal subjects, 2.91±1.04). In group A the heterogeneity of resting perfusion, expressed as coefficient of variation, was significantly different from the volunteers (20.1±4.5 vs 17.0±3.0,P<0.05). In group B (coefficient of variation 19.4±3.9) the difference from normal volunteers was not significant. In this study, patients with syndrome X and patients with minimal coronary artery disease showed normal perfusion responses during cold pressor stimulation and dipyridamole stress testing. Our findings therefore suggest that endothelial dysfunction and impaired vasodilator reserve are of no major pathophysiological relevance in patients with syndrome X. Rather, other mechanisms such as increased sympathetic tone and focal release of vasoactive substances may play a role in the pathogenesis of syndrome X. 相似文献