全文获取类型
收费全文 | 2213篇 |
免费 | 208篇 |
国内免费 | 3篇 |
专业分类
耳鼻咽喉 | 62篇 |
儿科学 | 54篇 |
妇产科学 | 43篇 |
基础医学 | 257篇 |
口腔科学 | 51篇 |
临床医学 | 273篇 |
内科学 | 392篇 |
皮肤病学 | 24篇 |
神经病学 | 184篇 |
特种医学 | 69篇 |
外科学 | 414篇 |
综合类 | 24篇 |
预防医学 | 223篇 |
眼科学 | 26篇 |
药学 | 151篇 |
中国医学 | 2篇 |
肿瘤学 | 175篇 |
出版年
2022年 | 18篇 |
2021年 | 52篇 |
2020年 | 27篇 |
2019年 | 36篇 |
2018年 | 39篇 |
2017年 | 40篇 |
2016年 | 46篇 |
2015年 | 64篇 |
2014年 | 59篇 |
2013年 | 93篇 |
2012年 | 153篇 |
2011年 | 150篇 |
2010年 | 76篇 |
2009年 | 54篇 |
2008年 | 117篇 |
2007年 | 103篇 |
2006年 | 117篇 |
2005年 | 89篇 |
2004年 | 87篇 |
2003年 | 83篇 |
2002年 | 52篇 |
2001年 | 48篇 |
2000年 | 68篇 |
1999年 | 43篇 |
1998年 | 20篇 |
1997年 | 15篇 |
1995年 | 20篇 |
1994年 | 22篇 |
1992年 | 45篇 |
1991年 | 33篇 |
1990年 | 33篇 |
1989年 | 29篇 |
1988年 | 30篇 |
1987年 | 32篇 |
1986年 | 33篇 |
1985年 | 26篇 |
1984年 | 23篇 |
1983年 | 21篇 |
1981年 | 16篇 |
1979年 | 22篇 |
1978年 | 21篇 |
1977年 | 15篇 |
1976年 | 26篇 |
1975年 | 14篇 |
1974年 | 19篇 |
1973年 | 19篇 |
1972年 | 13篇 |
1970年 | 15篇 |
1969年 | 16篇 |
1968年 | 14篇 |
排序方式: 共有2424条查询结果,搜索用时 343 毫秒
141.
142.
More than 300,000 deaths occur annually in the United States alone as a result of obesity, poor dietary habits, or physical inactivity. Obesity is now an increasingly recognized independent risk factor for cardiovascular disease and leads to numerous other comorbidities. The causal relationships between obesity and both insulin resistance and hypertension have been consistently demonstrated in numerous studies. The relationships consist of cascading events involving insulin, leptin, adiponectin, and other hormones that often precipitate the development of metabolic syndrome. As we learn more about the metabolic activity of the adipose tissue, we can better identify the mechanisms that associate weight reduction with a decrease in health risks. Evidence suggests that exercise produces a positive effect on weight reduction, insulin sensitivity, and blood pressure. Therefore, weight reduction and therapeutic changes in lifestyle should be encouraged in all overweight and obese patients. It is imperative to increase the awareness of the obesity epidemic and to emphasize the importance of exercise as both treatment and prevention of metabolic disease. 相似文献
143.
Immunoglobulin A (IgA) is transported into saliva by salivary cells expressing the polymeric immunoglobulin receptor (pIgR). In rat salivary glands, autonomic nerves stimulate this process. To examine how nerves affect pIgR-mediated IgA secretion, the chorda-lingual nerve was sectioned. One week after preganglionic parasympathectomy, both the stimulated and unstimulated rates of salivary IgA secretion were reduced, despite similar glandular amounts of IgA. Biochemical analysis of cells from parasympathectomised and control glands indicated reduced membrane expression of pIgR. It appears the removal of long-term parasympathetic input has affected the routing of pIgR within salivary cells and reduced the SIgA transport into saliva. 相似文献
144.
Proctor DD Henderson KJ Dziura JD Longacre AV White RI 《Journal of clinical gastroenterology》2005,39(2):115-119
OBJECTIVES: Hereditary hemorrhagic telangiectasia is an autosomal dominant disease in which 25% to 30% of patients will develop gastrointestinal bleeding from telangiectases. The extent of telangiectases has not been previously evaluated. This cross-sectional study compared the presence, number, and size of telangiectases in the stomach and duodenum to those in the jejunum using enteroscopy. METHODS: At the Yale University Vascular Malformation Center, 30 consecutive, symptomatic adult patients with hereditary hemorrhagic telangiectasia were evaluated using a 220-cm-length enteroscope. The number and size of the telangiectases were documented in the esophagus, proximal and distal stomach, four parts of the duodenum, and every 20 cm in the jejunum. The indication for the procedure was recorded as anemia, gastrointestinal bleeding, or anemia out of proportion to epistaxis. RESULTS: The results of 27 patients were analyzed. A total of 89% of patients had telangiectases in the first 60 cm of the jejunum. In individual patients, there was a strong correlation between the number of telangiectases in the stomach/duodenum when compared with the jejunum. In group analysis, the median number of telangiectases in the stomach and duodenum was significantly higher than in the jejunum (13 vs. 3; Wilcoxon signed rank test, P = 0.001). The presence of large (> or =5 mm) telangiectases in the stomach/duodenum did not necessarily indicate that there would be large telangiectases in the jejunum. CONCLUSIONS: The presence and number of stomach and duodenal telangiectases correlated with the presence and number of jejunal ones. However, the occurrence of large proximal telangiectases was not associated with large distal ones. 相似文献
145.
Patient misidentification in a pediatric emergency department: patient safety and legal perspectives
Emergency departments across the nation are faced with ever-increasing high volumes, overcrowding, and patient acuity. Along with these growing trends, the Joint Commission on the Accreditation of Healthcare Organizations is instituting new patient safety initiatives to reduce patient medical errors in the hospital setting. The emergency department is one area under great scrutiny with patient identification as primary concern. This article discusses a case study involving patient misidentification in the pediatric emergency department and reviews the legal and safety programs implemented at a children's hospital to improve patient safety outcomes. 相似文献
146.
RATIONALE, AIMS and OBJECTIVES: To document the natural history/clinical course of an unselected population presenting with first episode psychosis across a Mental Health Trust. METHOD: An observational database was set up covering all patients over 15 years of age. Data were collected at presentation and annual follow-up intervals. RESULTS: A total of 227 patients presented during the 3 years initial study period with a first episode psychosis. The commonest diagnoses were psychotic depression 19%, paranoid schizophrenia 11%, persistent delusional disorder 7% and bipolar affective disorder 7.5% giving an annual incidence of 30.36 per 100 000 population. At presentation, half had been admitted to hospital, nearly half of whom were detained under the Mental Health Act, and only a quarter were currently employed. Twenty-six per cent had an episode of deliberate self-harm and 14% had harmed others. A recurring pattern emerged of over half the patients being no longer in contact with mental health services 1 year after presentation. Data collection is ongoing. CONCLUSIONS: Clinical and managerial cooperation achieved a practical framework for data collection. This approach in an unselected population of patients yielded new insights into the course of first episode psychosis. The higher incidence than expected from the literature has implications for local strategic planning and provides a framework for detailed evaluation of a complex patient group. 相似文献
147.
Lewis KN 《The American surgeon》2004,70(1):91-93
The Greek language has shaped and formed the lexicon of modern medicine. Although medical terminology may seem complex and difficult to master, the clarity and functionality of this language owe a great debt to the tongue of the classical Greeks. 相似文献
148.
This study was undertaken to identify preoperative and intraoperative factors that correlate with the need for postoperative vasoactive medication (VM) use. Clinical data from 100 carotid endarterectomies (CEAs) performed in 93 patients were reviewed. Baseline comorbidities, medications, perioperative physiologic data, and operative technique were evaluated for their association with the need for postoperative VM use. Statistical analysis included univariate and multivariate logistic regression with odds ratios (ORs) and 95% confidence intervals (CIs) reported. Hemodynamic instability affected 43 patients, of whom 32 had VM started in the postanesthesia care unit (PACU). No patient who was hemodynamically stable in the PACU later required VM. The only preoperative factor associated with a need for postoperative VM was a prior stroke (OR 4.5; 95% CI 1.2-16.2; p = .02). Intraoperative factors associated with the need for postoperative VM included use of a shunt (OR 5.1; 95% CI 1.2-22.2; p = .03) and a peak intraoperative systolic blood pressure greater than 200 mm Hg (OR 5.1; 95% CI 1.2-22.2; p = .03). The number and type of preoperative blood pressure medications, preoperative hypertension, comorbidities, symptomatic presentation, and intraoperative use of VM did not correlate with postoperative VM use. There were two strokes and no deaths. Patients undergoing CEA who are hemodynamically stable in the PACU appear to be reasonable candidates for same-day discharge and warrant further prospective study. 相似文献
149.
Yu M Cambj-Sapunar L Kehl F Maier KG Takeuchi K Miyata N Ishimoto T Reddy LM Falck JR Gebremedhin D Harder DR Roman RJ 《European journal of pharmacology》2004,486(3):297-306
This study examined the effects of a 20-hydroxyeicosatetraenoic acid (20-HETE) antagonist, 20-hydroxyeicosa-6(Z),15(Z)-dienoic acid (WIT002) and two agonists, 4-amino-N-(20-hydroxy-eicosa-5(Z),14(Z)-dienoyl) benzenesulfonamide (ABSA) and 20-hydroxyeicosa-5(Z),14(Z)-dienoic acid (WIT003), on the diameter of rat middle cerebral arteries in vitro and on cerebral blood flow in vivo. WIT003, ABSA and 20-HETE all had a similar effect to reduce the diameter of the middle cerebral artery by 26%. WIT003 and 20-HETE both increased intracellular Ca2+ concentration ([Ca2+]i) in vascular smooth muscle cells isolated from the middle cerebral artery. In contrast, WIT002 had no effect on the basal diameter of the middle cerebral artery but it attenuated the vasoconstrictor responses and the rise in [Ca2+]i in vascular smooth muscle cells following administration of 20-HETE and 5-hydroxytryptamine (5-HT). WIT003 partially restored the vasoconstrictor response to 5-HT in the middle cerebral artery after administration of an inhibitor of the endogenous synthesis of 20-HETE. Infusion of the 20-HETE agonists, WIT003 and ABSA, into cisterna magna of rats reduced baseline cerebral blood flow by 20%, whereas administration of the 20-HETE antagonist, WIT002, had no effect. Intracisternal injection of WIT002 attenuated the fall in cerebral blood flow following injection of blood into the cisterna magna, whereas administration of the 20-HETE agonist, ABSA, potentiated this response. These findings indicate that the 20-HETE agonists, WIT003 and ABSA, increase cerebral vascular tone both in vivo and in vitro and suggest blocking the vasoconstrictor actions of 20-HETE may be useful to prevent the acute fall in cerebral blood flow following subarachnoid hemorrhage. 相似文献
150.
The global smoking epidemic: a history and status report 总被引:2,自引:0,他引:2
Proctor RN 《Clinical lung cancer》2004,5(6):371-376
The World Health Organization estimates that tobacco causes approximately 5 million deaths annually worldwide, a number expected to double by 2025. Cigarette consumption grew from only a few billion per year in 1900 to present values of approximately 5.5 trillion worldwide. Historical causes for the rise of smoking include the invention of flue curing, safety matches, and cigarette rolling machines, but also the distribution of cigarettes to soldiers during World War I, mass marketing, the failure of governments to limit consumption, and the duplicitous denial of hazards by manufacturers. Cancers of the lip, throat, and tongue were linked to tobacco as early as the 18th century, but a lung cancer hazard from smoking was not suspected until the first decade of the 20th century. Epidemiologic evidence began to emerge in the 1920s, and by the 1950s, the causal link with cigarette smoking was well established. Epidemiologic studies, animal experiments, and studies demonstrating pathologic changes in lung tissues at autopsy were 3 pivotal sources of evidence. However, the tobacco industry refused to concede the reality of tobacco hazards until the late 1990s. Instead, the industry sought to target physicians and others with its message of "no proof," using subtle techniques of deception, including the funding of spurious research, duplicitous press releases, propaganda efforts directed at physicians, and the employment of historians to construct exculpatory narratives. The World Health Organization's Framework Convention on Tobacco Control promises to standardize global tobacco control measures, including policies to limit smuggling. Effective means of reducing tobacco use include counter-advertising, increased taxation, smoke-free workplace legislation, and litigation against the industry. 相似文献