全文获取类型
收费全文 | 10995篇 |
免费 | 551篇 |
国内免费 | 68篇 |
专业分类
耳鼻咽喉 | 112篇 |
儿科学 | 212篇 |
妇产科学 | 148篇 |
基础医学 | 1269篇 |
口腔科学 | 249篇 |
临床医学 | 720篇 |
内科学 | 2999篇 |
皮肤病学 | 143篇 |
神经病学 | 650篇 |
特种医学 | 442篇 |
外科学 | 1992篇 |
综合类 | 63篇 |
一般理论 | 1篇 |
预防医学 | 320篇 |
眼科学 | 295篇 |
药学 | 604篇 |
中国医学 | 15篇 |
肿瘤学 | 1380篇 |
出版年
2023年 | 85篇 |
2022年 | 117篇 |
2021年 | 211篇 |
2020年 | 129篇 |
2019年 | 156篇 |
2018年 | 246篇 |
2017年 | 192篇 |
2016年 | 246篇 |
2015年 | 224篇 |
2014年 | 328篇 |
2013年 | 313篇 |
2012年 | 508篇 |
2011年 | 604篇 |
2010年 | 367篇 |
2009年 | 295篇 |
2008年 | 435篇 |
2007年 | 489篇 |
2006年 | 496篇 |
2005年 | 509篇 |
2004年 | 470篇 |
2003年 | 410篇 |
2002年 | 428篇 |
2001年 | 365篇 |
2000年 | 363篇 |
1999年 | 310篇 |
1998年 | 121篇 |
1997年 | 87篇 |
1996年 | 83篇 |
1995年 | 89篇 |
1994年 | 77篇 |
1993年 | 85篇 |
1992年 | 267篇 |
1991年 | 214篇 |
1990年 | 223篇 |
1989年 | 256篇 |
1988年 | 207篇 |
1987年 | 211篇 |
1986年 | 193篇 |
1985年 | 185篇 |
1984年 | 127篇 |
1983年 | 109篇 |
1980年 | 42篇 |
1979年 | 91篇 |
1978年 | 68篇 |
1977年 | 52篇 |
1973年 | 42篇 |
1972年 | 42篇 |
1971年 | 43篇 |
1970年 | 45篇 |
1968年 | 48篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Correlation between bone marrow edema and collapse of the femoral head in steroid-induced osteonecrosis 总被引:26,自引:0,他引:26
Iida S Harada Y Shimizu K Sakamoto M Ikenoue S Akita T Kitahara H Moriya H 《AJR. American journal of roentgenology》2000,174(3):735-743
OBJECTIVE: The purpose of this study was to clarify whether bone marrow edema is detectable on initial MR imaging of steroid-induced osteonecrosis of the femoral head. SUBJECTS AND METHODS: Forty-eight hips with osteonecrosis were examined consecutively with MR imaging and radiography. In a previously reported screening program, osteonecrosis was diagnosed on MR imaging when subchondral bands of abnormal signals were present. In the screening program, the MR images of 200 hips of 100 patients receiving high-dose steroid therapy were examined prospectively. Subchondral bands were detected in 48 hips at a mean of 14 weeks after the initiation of steroid therapy. RESULTS: On follow-up MR imaging of 47 hips (one hip excluded) bone marrow edema was initially observed in 13 hips after the onset of hip pain. MR imaging of the remaining 34 hips did not reveal bone marrow edema and the patients were all asymptomatic. MR imaging of 31 of the 34 hips continued to show subchondral bands and MR imaging of the other three hips indicated that the subchondral bands had disappeared. When bone marrow edema was detectable, abnormal findings on radiography were slight but 11 (85%) of the 13 hips progressed to advanced osteonecrosis. Bone marrow edema was highly correlated with the subsequent collapse of the femoral head (p<0.0001). CONCLUSION: Bone marrow edema was not present on initial MR imaging of osteonecrosis. Bone marrow edema should be considered a marker for potential progression to advanced osteonecrosis, and careful examinations for osteonecrosis are necessary when bone marrow edema is seen. 相似文献
102.
To investigate the functional involvement of the pineal gland in circadian expression of the rat period homolog gene (rPer2) in the suprachiasmatic nucleus (SCN) and peripheral tissues, we performed Northern blot analysis in tissues from pinealectomized rats. The ectomy did not have any significant effects on rPer2 mRNA expression patterns both in a daily light-dark condition and in a constant darkness. These results suggest that the rhythmic secretion of pineal melatonin is not essential for the circadian expression of clock genes in the SCN and other peripheral tissues of rats. 相似文献
103.
104.
To evaluate the steno-occlusive changes in the external carotid system in moyamoya disease, cerebral angiograms of 39 moyamoya patients were retrospectively reviewed. There were 26 females and 13 males, age ranged from 4 to 62 years with a mean of 26 years. Initial symptoms were ischaemia in 27 patients, haemorrhage in 9, and none in 3. Stenosis, occlusion, and dilatation in the external carotid system were analysed angiographically. No stenosis or occlusion of the superficial temporal artery, middle meningeal artery, or occipital artery was observed in either preoperative or postoperative follow-up angiograms in any patients. Steno-occlusive changes do not occur in the external carotid system, but are confined in the internal carotid system in moyamoya disease. 相似文献
105.
Sakamoto K Kase M Mo M Kurata H 《Kyobu geka. The Japanese journal of thoracic surgery》2000,53(1):74-77
Mature teratomas occasionally rupture into adjacent organs such as lung, bronchus, mediastinum and pericardial sac. However, perforation into the pericardial sac is rare. We experienced a case of mediastinal mature teratoma perforated into the pericardial sac. A 16-year-old man was admitted to our hospital due to sudden severe anterior chest pain. Chest X-ray showed a mass shadow in the right middle lung field. Chest CT scan and MRI demonstrated a heterogeneous mass with fat component in the right anterior mediastium adjacent to the pericardium. Some squamous cells were obtained from the mass by CT guided percutaneous needle biopsy. Operation was performed with the diagnosis of mediastinal teratoma. The mass adhered to the pericardium and turbid pericardial effusion was noted. The mass was removed with the pericardium. The mass was 9 x 6.5 x 6 cm in size, which contained yellow sebaceous material and a tuft of white hair. The pathological diagnosis of the mass was mature cystic teratoma with perforation into the pericardial sac. 相似文献
106.
Kase M Sakamoto K Yamagata T Watanabe K Kunikane H Okamoto H Nagatomo A 《Kyobu geka. The Japanese journal of thoracic surgery》2000,53(12):1055-1057
A 29-year-old woman was referred to our hospital for an abnormal shadow on chest roentgenogram. She had no symptom but its shadow was pointed out about 20 years ago. Chest CT scan showed a sharply demarcated homogenous mass measured 10 x 10 mm in the S4 segment. The tumor was resected with video-assisted thoracoscopic surgery under CT-guided marking wire inserted. Microscopic examination suspected cavernous hemangioma. Immunohistological staining demonstrated most lining cells of the cavernous structure stained positively for von Willebrand factor antibody, which suggests that this tumor was associated with endothelium. Then we decided that this tumor was pulmonary cavernous hemangioma. 相似文献
107.
Okubo Akiko Sameshima Munefumi Sakamoto Taiji 《Albrecht von Graefes Archiv fur klinische und experimentelle Ophthalmologie》2004,242(11):962-965
Purpose The aim of this study was to describe the clinical course in a patient with polypoidal choroidal vasculopathy (PCV).Methods A 68-year-old man with PCV in the left eye was followed up by means of routine examinations including fluorescein angiography and indocyanine green angiography for over 60 months.Results Throughout the follow-up period, the patient experienced repeated lesions in the macula, such as serosanguineous detachment of the retinal pigment epithelium and neurosensory retina, but retained good visual acuity. Indocyanine green angiography disclosed spontaneous regression of polypoidal vessels followed by significant changes in the choroidal circulation: a group of polypoidal structures disappeared, and after several months a small choroidal vessel became apparent that was distant from the previously observed polypoidal structure rather than representing an extension of the original lesion.Conclusion The clinical observation suggests that in some cases of PCV the choroidal vasculature may be altered with time, in that some vessels in the inner choroid and even the choriocapillaris may close and collateral vessels and/or new vessels may develop to form complex such as that described here. 相似文献
108.
109.
We described a 28-year-old woman with systemic lupus erythematosus (SLE) presented with digestive tract, skin and renal symptoms and afterwards developed acute cerebellar ataxia, a paresis of the right inferior rectus muscle, left abducens paralysis and left facial palsy which seemed to be consistent with a brainstem lesion visible on magnetic resonance imaging (MRI). This lesion disappeared within 9 days of corticosteroid treatment. It is suggested that this lesion is focal edema induced by acute changes in the blood brain barrier secondary to a vasculopathy. Other causes, including local infarction, are unlikely. 相似文献
110.
Light-induced phase-shifts in the circadian expression rhythm of mammalian period genes in the mouse heart 总被引:4,自引:0,他引:4
To investigate the molecular mechanism that regulates circadian rhythms in mammalian peripheral tissues, we examined the phase shifts evoked by light exposure in the circadian mRNA expression rhythms of mammalian Period genes (mPer1, mPer2 and mPer3) and a clock-controlled gene Dbp, in the mouse heart, by Northern blot analysis. The light pulse did not induce any acute mRNA expression of mPer in the heart, but the pulse gave rise to phase shifts in the circadian mRNA rhythms. On the first day after the exposure, only mPer1 mRNA showed a phase shift, whereas obvious phase shifts were not observed in the rhythms of mPer2, mPer3 and Dbp mRNAs. On the second day, phase shifts occurred to a similar extent in the mRNA rhythms of all four genes examined. The rhythm of mPer1 mRNA shifted fastest among those of the three mPers. Therefore mPer1 seems to play an important role in phase resetting of mammalian peripheral oscillators. Immediate responses to light pulses in mRNA expression of mPers may not be required for phase shifting of peripheral circadian oscillators. Our findings suggest that mammals require more than one day to have peripheral oscillators entrained to a new daily schedule. 相似文献