首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   8454篇
  免费   387篇
  国内免费   69篇
耳鼻咽喉   81篇
儿科学   167篇
妇产科学   83篇
基础医学   992篇
口腔科学   128篇
临床医学   569篇
内科学   2062篇
皮肤病学   106篇
神经病学   623篇
特种医学   346篇
外科学   1885篇
综合类   27篇
现状与发展   1篇
预防医学   153篇
眼科学   110篇
药学   531篇
中国医学   8篇
肿瘤学   1038篇
  2023年   68篇
  2022年   125篇
  2021年   190篇
  2020年   119篇
  2019年   161篇
  2018年   191篇
  2017年   168篇
  2016年   228篇
  2015年   226篇
  2014年   286篇
  2013年   338篇
  2012年   535篇
  2011年   580篇
  2010年   366篇
  2009年   321篇
  2008年   542篇
  2007年   596篇
  2006年   589篇
  2005年   580篇
  2004年   597篇
  2003年   537篇
  2002年   518篇
  2001年   74篇
  2000年   63篇
  1999年   84篇
  1998年   113篇
  1997年   92篇
  1996年   92篇
  1995年   76篇
  1994年   72篇
  1993年   58篇
  1992年   55篇
  1991年   36篇
  1990年   40篇
  1989年   26篇
  1988年   27篇
  1987年   17篇
  1986年   16篇
  1985年   14篇
  1984年   14篇
  1983年   11篇
  1982年   13篇
  1981年   11篇
  1980年   11篇
  1979年   5篇
  1978年   13篇
  1977年   2篇
  1976年   3篇
  1966年   2篇
  1936年   2篇
排序方式: 共有8910条查询结果,搜索用时 3 毫秒
991.
Summary: Epileptiform discharges in 8 electrode waking EEGs at rest and during hyperventilation in 1,057 healthy children aged 6–12 years from an elementary school were studied: Epileptiform discharges, detected in 53 children (5.0%), consisted of centrotemporal spikes (37 cases), generalized spike ahd slow wave complexes (10 cases), occipital spikes (2 cases), frontal spikes (1 case), and a combination of multiple spike and slow wave complexes and focal spikes (2 cases). The occurrence of a positive past history of febrile convulsions was higher in children with epileptiform discharges (18.9%) than in those without epileptiform discharges (9.4%). Using the Rutter scales for teachers and parents, we compared the emotional and behavioral problems of children with epileptiform EEG discharges with those of children without epileptiform discharges. No statistically significant differences were noted, indicating that the emotional and behavioral problems existing are most probably coincidental and not directly related to the epileptiform discharges. A genetic basis for generalized epileptiform discharges was postulated because the occurrence of generalized discharges in siblings of probands with generalized discharges was higher (4 of 9, 44.4%) than the prevalence in all subjects. However, the occurrence of centrotemporat spikes in the siblings of probands with centrotemporal spikes was not higher (2/38, 5.3%) and an autosomaldominant genetic factor for centrotemporal spikes in waking EEGs of healthy children could not be confirmed.  相似文献   
992.
Local heating of nonglabrous skin increases skin blood flow (SkBF) in two phases. The initial peak (P1) is mediated by a sensory-axon reflex and the plateau phase (P2) by local production of substances such as nitric oxide. We evaluated the SkBF response to local heating in 15 multiple system atrophy (MSA) patients with autonomic failure and 12 age-matched healthy controls. The mean ratio of SkBF at P1 to that at baseline (SkBF(P1)/SkBF(base) ratio) in MSA was significantly lower than that in controls (P < 0.01). The mean ratio of SkBF at P2 seemed to be slightly reduced in the MSA patients, compared with controls, although there was no significant difference. The P1 phase is thought to be mediated by a sensory-axon reflex modulated by sympathetic nerve activity. These findings are indicative of the skin sympathetic vasomotor dysfunction in MSA.  相似文献   
993.
994.
This study investigates the ability of low doses of angiotensin-converting-enzyme inhibitors, in combination with angiotensin II receptor blockers, to exert antiproteinuric effects in normotensive and proteinuric outpatients with immunoglobulin A (IgA) nephropathy confirmed by biopsy. We performed a prospective, randomized, 6-month study of the effects of temocapril 1 mg (n=10), losartan 12.5 mg (n=10), and both (n=11) on mild-to-moderate proteinuria 0.76+/-0.35 g/day (range, 0.4 to 1.6 g/day) and renal function. The study subjects comprised 31 normotensive and proteinuric outpatients with IgA nephropathy accompanied by normal, or mild-to-moderately reduced but stable renal function (glomerular filtration rate>50 ml/min) without steroid or immunosuppressive therapy. We prospectively evaluated blood pressure, proteinuria, renal function and biochemical parameters before and after 6 months of therapy. The combination therapy significantly reduced proteinuria (63.2%) compared with either temocapril or losartan alone (41.3% and 36.6%, respectively, p=0.04 and 0.01, respectively). Blood pressure was most decreased in the group that received combination therapy. The reduced proteinuria did not correlate with reduced systolic or diastolic blood pressure or mean arterial pressure in any of the groups. The glomerular filtration rate fell during the first 3 months of combined therapy, but became reversible after a further 3 months of therapy. The combination significantly decreased angiotensin II (p <0.01), and this decrease was greater than that by either drug alone. In conclusion, the effectiveness of the combined therapy may have been at least partly due to the greater inhibition of the action of angiotensin II in patients with IgA nephropathy. This strategy apparently reduced mild-to-moderate proteinuria in patients with normotensive IgA nephropathy.  相似文献   
995.
We reviewed the results of 35 operations performed on 29 patients with osteonecrosis of the femoral head in which a pedicle iliac bone was utilized. The average age was 35 years (17–62). There were 28 patients of stage 2 and 7 of stage 3; there were 17 type C-1 hips and 18 type C-2 hips. The pedicle bone was inserted in the anterolateral direction of the femoral head. The average follow-up period was 8 years and 7 months. Collapse of the femoral head occurred in 19 hip joints. Although 16 of 28 stage 2 hips showed collapse, all 7 stage 3 hips resulted in collapse. Thirteen of 17 hips did not show collapse in patients with type C-1 necrosis, whereas 15 of 18 hips developed collapse in patients with type C-2 necrosis. When the bone graft was inserted in the anterolateral direction of the femoral head, incidence of collapse was reduced. These results indicate that deep circumflex iliac pedicle bone graft may be indicated for stage 2 type C-1 necrosis, and that the penetration of the graft into the anterolateral aspect of the lesion is essential for the procedure to succeed.  相似文献   
996.
Neuroblastoma rarely occurs in adults, in whom prognosis is poor. Here we report on the effective use of multimodal therapy to achieve long-term survival in adult mediastinal neuroblastoma. In a 33-year-old male with severe pain radiating from the left hypochondrium to the back area, no abnormal shadow was detected on first examination; the shadow appeared in chest X-ray only 10 months later when the severe pain recurred. The patient was then referred to our department for further examination. Chest X-rays and chest CT scans revealed a posterior mediastinal mass beside the thoracic vertebrae. Diagnosis was confirmed after surgical resection, which was followed by outpatient adjuvant therapy through radiation and chemotherapy. The patient has survived 8 years and 8 months without recurrence or metastasis.  相似文献   
997.
We examined the microscopic features and distribution of collagens in the hyperplastic intima of arterially implanted autovein bypass grafts under conditions of a reduced blood flow with a poor distal outflow. Vascular anastomosis was made using 7–0 nonabsorbable polypropylene sutures (PP group), or absorbable polydioxanone sutures (PDS group). On the contralateral limb, an autovein bypass graft was performed under normal flow conditions (NF group). The thickness of the intima in the NF group was approximately 50μm throughout the duration of the study, while in the PP and PDS groups, intimal hyperplasia progressed to 290±112μm and 267±123 μm, respectively, at 13 months after grafting. Collagen accumulated significantly in both the PP and PDS groups; types IV and V collagen in particular increased considerably in the deep layer. Regardless of the suture materials, the progression of intimal hyperplasia was considered to be closely related to the poor distal outflow to be and caused by the proliferation of myofibroblasts and active production of collagen. The increase in types IV and V collagen, particularly in the deep layer of the hyperplastic intima, was due to development of numerous vasa vasora in this region.  相似文献   
998.
We present a case of early tissue failure of the Medtronic Freestyle stentless bioprosthesis used in the aortic position which led to reoperation 27 months after implantation. Almost one half of the left coronary cusp of the prosthetic valve had torn away along the annulus. The tear started from the left-non coronary commissure and reached the midpoint of the base of the left coronary cusp. The prosthetic valve was easily excised and replaced with a new mechanical valve. There was no sign of calcification or vegetation in the excised valve. The cause of the valve dysfunction was thought to be primary tissue failure. Long-term function of the Freestyle stentless valve should be carefully followed up.  相似文献   
999.
Fenestration of the internal carotid artery (ICA) is extremely rare on clinical settings. Six cases of fenestration in intracranial and 8 in extracracranial ICA have ever been reported in literature. Authors describe two cases of fenestration at the extracranial ICA that were initially suspected of the dissection of ICA on MRA/I. Both angiography and CT angiography (CTA) disclosed the fenestration, which located at C2 vertebral levels. To confirm the fenestration at extracranial ICA is important in such an occasion that mimic the dissection of ICA, especially in patients who complain of cervical pain, mass and other related symptoms. Differences in the fenestration, the dissection and atherosclerosis on imaging, were reviewed and discussed.  相似文献   
1000.
Summary: Mesangial cell growth stimulation by endothelin (ET) and arginine vasopressin (AVP) has been reported, but only in studies using late (3 times) pasaged cells. In the present study, we examined the effects of ET, AVP and platelet activating factor (PAF) on the proliferation of early (<3 times) passaged cultured rat mesangial cells which maintained their original characteristics. Cell growth was estimated by [3H]-thymidine incorporation into DNA and by counting cell nuclei. After 48 h preincubation in minimal essential medium containing 0.5% fetal calf serum, ET-1 (1-100 nmol/L), AVP (100 pmol/L-1 μmol/L) or PAF (1–100 nmol/L) was added to the incubation medium. In contrast to studies using late passaged cells, ET-1 attenuated and AVP did not increase thymidine uptake (ET-1: 18.4% inhibition at 10 nmol/L) or cell counts in early passaged cells, while the growth stimulatory effects of these agents were reproduced in late passaged cells. Platelet activating factor showed definite stimulation of cell growth in both early and late passaged cells in a dose-dependent manner. These data strongly suggest that ET-1 attenuates, and AVP does not stimulate, the cell growth of original mesangial cells. the PAF-induced cell growth seems to be the constant feature of mesangial cells in vivo.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号