全文获取类型
收费全文 | 1959171篇 |
免费 | 149848篇 |
国内免费 | 3292篇 |
专业分类
耳鼻咽喉 | 27130篇 |
儿科学 | 60946篇 |
妇产科学 | 55486篇 |
基础医学 | 288923篇 |
口腔科学 | 56315篇 |
临床医学 | 178932篇 |
内科学 | 375945篇 |
皮肤病学 | 41141篇 |
神经病学 | 158590篇 |
特种医学 | 75006篇 |
外国民族医学 | 419篇 |
外科学 | 288760篇 |
综合类 | 46473篇 |
现状与发展 | 4篇 |
一般理论 | 805篇 |
预防医学 | 159623篇 |
眼科学 | 45253篇 |
药学 | 145140篇 |
7篇 | |
中国医学 | 3435篇 |
肿瘤学 | 103978篇 |
出版年
2018年 | 19382篇 |
2016年 | 16579篇 |
2015年 | 19203篇 |
2014年 | 26946篇 |
2013年 | 41319篇 |
2012年 | 55932篇 |
2011年 | 59372篇 |
2010年 | 34514篇 |
2009年 | 32899篇 |
2008年 | 56114篇 |
2007年 | 60429篇 |
2006年 | 59912篇 |
2005年 | 58762篇 |
2004年 | 56887篇 |
2003年 | 54590篇 |
2002年 | 52940篇 |
2001年 | 83546篇 |
2000年 | 85070篇 |
1999年 | 72010篇 |
1998年 | 21008篇 |
1997年 | 19185篇 |
1996年 | 19467篇 |
1995年 | 18262篇 |
1994年 | 17280篇 |
1993年 | 16226篇 |
1992年 | 58935篇 |
1991年 | 57816篇 |
1990年 | 56330篇 |
1989年 | 54503篇 |
1988年 | 50896篇 |
1987年 | 50035篇 |
1986年 | 47591篇 |
1985年 | 45424篇 |
1984年 | 34934篇 |
1983年 | 30308篇 |
1982年 | 18510篇 |
1981年 | 16924篇 |
1979年 | 34360篇 |
1978年 | 25158篇 |
1977年 | 20993篇 |
1976年 | 19388篇 |
1975年 | 21125篇 |
1974年 | 25875篇 |
1973年 | 25189篇 |
1972年 | 24041篇 |
1971年 | 22271篇 |
1970年 | 21202篇 |
1969年 | 20189篇 |
1968年 | 18567篇 |
1967年 | 16862篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
The value of ultrasound in the diagnosis of a large rapidly growing thyroid mass was assessed in a study of 42 patients with a large (> 3 cm) rapidly growing (< two months) solitary mass. Haemorrhage into a thyroid nodule was present in 31 patients and thyroid malignancy in 11. Ultrasound of haemorrhage into a thyroid nodule revealed a large cystic mass in all 31 patients containing internal debris (22), septations (three), or a combination of both (six). The malignant causes of a large rapidly growing mass were lymphoma (two), anaplastic carcinoma (four) and metastasis (five). Ultrasound of these thyroid malignancies revealed a mass with a smooth, well-defined margin and strikingly low homogeneous echogenicity in all cases. Patients with thyroid metastases had evidence of widespread metastatic disease elsewhere. Lymphoma was differentiated from anaplastic carcinoma on fine-needle aspiration cytology or surgical biopsy. Ultrasound was of value in differentiating between a benign haemorrhagic nodule and a malignant tumour. The various malignant tumours had similar appearances, however, and could not be distinguished on ultrasound. 相似文献
92.
Low signal intensity on long-repetition-time MR sequences has been observed in deep gray matter structures in patients with multiple sclerosis. This T2 shortening most likely represents a nonspecific degenerative process. We recently observed T2 shortening in the pericentral cortical gray matter and subcortical white matter in a patient with severe multiple sclerosis and we postulate that this represents an additional manifestation of neural degeneration. 相似文献
93.
Piecewise constant incidence models were developed to estimate the force of infection in women from age-and time-specific antenatal or neonatal seroprevalence data. Differential inclusion of infected women in sero-surveys compared to uninfected women was taken into account, with respect to both changes in inclusion rate following infection, and changes in relative inclusion rate over calendar time. These models were applied to anonymous HIV seroprevalence data collected from neonates born to black and Hispanic women in New York City 1988-1992, with incidence and fertility parameters estimated by maximum likelihood. Estimates of inclusion rate parameters accorded well with what is known about the natural history of HIV. The data could not distinguish between additive and multiplicative combination of the effects of age and time on incidence. Incidence was strongly dependent on age with the highest incidence in women aged 20-34 years. There was strong evidence that incidence had been falling in Hispanic women since 1982-1984. The results illustrate the extent to which trends in incidence over time may be confounded by changes in the relative inclusion rate of infected and uninfected women. 相似文献
94.
95.
Precise and limited decompression for lumbar spinal stenosis 总被引:3,自引:0,他引:3
Summary Fifty-eight consecutive patients with lumbosacral nerve root entrapment due to spinal stenosis were treated with modified microsurgical decompression. Only the clinically relevant sides and levels were decompressed while the spinous processes, the interspinous ligaments, the medial portion of ligamentum flavum and the functionally important parts of the facet joints were preserved. The reviewers rated recovery as good or excellent in 71% of patients while patient self-assessment indicated 76% good or excellent outcome. These data suggest that microsurgical decompression of spondyloarthritic changes can effectively relieve the signs and symptoms of nerve root compression and that with careful evaluation of all available data the number of nerve roots requiring decomperession is often fewer than what is suggested by diagnositic images alone. 相似文献
96.
97.
F W Fraunfelder F T Fraunfelder D R Illingworth 《The British journal of ophthalmology》1995,79(1):54-56
In a retrospective survey of patients taking medication for hyperlipidaemia, those taking niacin (nicotinic acid) were more likely (p < 0.05) to report sicca syndromes, blurred vision, eyelid oedema, and macular oedema compared with those who never took niacin. Additionally, 7% of those taking niacin discontinued the drug owing to adverse ocular side effects, while none of the other lipid lowering agents were found to cause these side effects (p = 0.016). Data from spontaneous reporting systems support a possible association of decreased vision, cystoid macular oedema, sicca-like symptoms, discoloration of the eyelids with or without periorbital or eyelid oedema, proptosis, loss of eyebrow or eyelashes, and superficial punctate keratitis with the use of niacin in high doses. Decreased vision may be marked, and if the drug is not discontinued, may progress to cystoid macular oedema. All ocular side effects listed above are reversible if the association with niacin is recognised and the drug is discontinued; both the incidence and severity of the ocular side effects seem to be dose dependent. 相似文献
98.
99.
Although malignant fibrous histiocytoma (MFH) is the most common soft tissue sarcoma of adult life, it is fairly rare in the head and neck region (3-6%). Between 1983 and 1991 8 patients with MFH in the head and neck region have been observed and treated at the ENT-department of the University of Tübingen. 5 patients have been operated (laryngopharyngeal localization), 2 patients underwent irradiation (unresectable fast growing T4-tumors of the pharynx and thyroid) and one female patient refused further therapy after two resections elsewhere. Operated patients showed no evidence of disease 2-8 years after resection (all margins have been controlled histologically). Both irradiated patients died 4 respectively 2 months after full (70 Gy) and incomplete (17 Gy) radiotherapy without visible positive effects. Both patients developed pulmonary metastasis. Since MFH can grow in thin layers along musculaoponeurotic structures the exact size is not always demonstrable by ultrasound, CT or MR scans. Metastasis occur in up to 40%, preferentially in regionary lymph nodes, in lung, liver and skeletal system. These phenomenon requires a full pretherapeutic staging. Histologically MFH is sometimes hard to distinguish from other tumors as for example various sarcomas and pleomorphic carcinoma. Therefore, immunohistochemical (mesenchymal markers) and electron microscopical investigations are advised. Resection with exact histological controll of all margins is the therapy of choice. We experienced that laryngeal MFH (n = 3) can be resected without laryngectomy under certain circumstances. Although unsuccessfull in our two cases, according to the literature, radiotherapy should be administered in unresectable cases. Depending on localization and size of MFH long survival, in single cases healing, of this disease is possible by surgical treatment. 相似文献
100.
C Schmitt J Brachmann W Saggau T Beyer B Waldecker K Scharowski T Hilbel M Montero B Offner W Sch?ls 《Zeitschrift für Kardiologie》1991,80(11):665-672
In 41 patients with recurrent sustained ventricular tachycardia and/or ventricular fibrillation an integrated pacemaker-defibrillator-system (PCD, Medtronic, model 7216 A or 7217 B) was implanted. In 21 out of 24 (88%) patients a new transvenous implantation technique in combination with a subcutaneous patch electrode was used. The implanted devices comprise antibradycardiac pacemaker functions, two different forms of antitachycardiac pacemaker functions (ramp and burst pacing), and internal cardioversion or defibrillation capabilities. During a mean follow-up of 8 months 147 episodes of ventricular tachycardia were detected, 131 of them were terminated successfully by antitachycardiac pacing; in 13 episodes internal cardioversion was applied to revert ventricular tachycardia. Twenty-seven episodes of ventricular fibrillation or rapid ventricular tachycardia (greater than 200/min) were detected and successfully terminated by internal defibrillation. In six patients with intermittent rapid atrial fibrillation, change of antiarrhythmic therapy was required to avoid activation of the device. The new integrated pacemaker-defibrillator systems improve therapy in patients with life-threatening tachyarrhythmias by reducing the number of internal cardioversions/defibrillations; the non-thoracotomy approach reduces the post operative risk. 相似文献