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   44561篇
  免费   2846篇
  国内免费   256篇
耳鼻咽喉   382篇
儿科学   1291篇
妇产科学   1200篇
基础医学   5894篇
口腔科学   935篇
临床医学   4474篇
内科学   9736篇
皮肤病学   879篇
神经病学   4781篇
特种医学   1495篇
外科学   5894篇
综合类   175篇
一般理论   19篇
预防医学   3289篇
眼科学   762篇
药学   2759篇
  1篇
中国医学   84篇
肿瘤学   3613篇
  2024年   53篇
  2023年   472篇
  2022年   769篇
  2021年   1799篇
  2020年   1056篇
  2019年   1484篇
  2018年   1698篇
  2017年   1189篇
  2016年   1336篇
  2015年   1542篇
  2014年   2120篇
  2013年   2640篇
  2012年   3913篇
  2011年   3901篇
  2010年   1972篇
  2009年   1842篇
  2008年   3110篇
  2007年   2999篇
  2006年   2701篇
  2005年   2673篇
  2004年   2231篇
  2003年   1995篇
  2002年   1766篇
  2001年   225篇
  2000年   156篇
  1999年   229篇
  1998年   301篇
  1997年   222篇
  1996年   198篇
  1995年   180篇
  1994年   154篇
  1993年   121篇
  1992年   84篇
  1991年   75篇
  1990年   62篇
  1989年   41篇
  1988年   39篇
  1987年   34篇
  1986年   31篇
  1985年   31篇
  1984年   38篇
  1983年   19篇
  1982年   39篇
  1981年   24篇
  1980年   21篇
  1979年   9篇
  1978年   12篇
  1977年   12篇
  1976年   8篇
  1972年   8篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
61.
62.
Background Oxidative stress and increased inflammation have been reported to be increased in subjects with diabetes and to be involved in the pathogenesis of cardiovascular complications after myocardial infarction (MI). It is well recognized that red wine has antioxidant and anti‐inflammatory activities. We examined the effects of moderate red wine intake on echocardiographic parameters of functional cardiac outcome in addition to inflammatory cytokines and nitrotyrosine (oxidative stress marker), in subjects with diabetes after a first uncomplicated MI. Methods One hundred and fifteen subjects with diabetes who had sustained a first non‐fatal MI were randomized to receive a moderate daily amount of red wine (intervention group) or not (control group). Echocardiographic parameters of ventricular dys‐synchrony, circulating levels of nitrotyrosine, tumour necrosis factor‐α (TNF‐α), interleukin‐6 (IL‐6), interleukin‐18 (IL‐18) and C‐reactive protein (CRP) were investigated at baseline and 12 months after randomization. Results After 1 year of diet intervention, concentrations of nitrotyrosine (P < 0.01), CRP (P < 0.01), TNF‐α (P < 0.01), IL‐6 (P < 0.01) and IL‐18 (P < 0.01) were increased in the control group compared with the intervention group. In addition, myocardial performance index (P < 0.02) was higher, and transmitral Doppler flow (P < 0.05), pulmonary venous flow analysis (P < 0.02) and ejection fraction (P < 0.05) were lower in the control group, indicating ventricular dys‐synchrony. The concentrations of nitrotyrosine, CRP, TNF‐α and IL‐6 were related to echocardiographic parameters of ventricular dys‐synchrony. Conclusions In subjects with diabetes, red wine consumption, taken with meals, significantly reduces oxidative stress and pro‐inflammatory cytokines as well as improving cardiac function after MI. Moderate red wine intake with meals may have a beneficial effect in the prevention of cardiovascular complications after MI in subjects with diabetes.  相似文献   
63.
This study looked at the relationship between athletic identity and three levels of sport participation (elite, recreational, non-participation). Athletic identity was measured using the Athletic Identity Measurement Scale (AIMS) with participants being compared on the total AIMS score and scores on its three factors (social identity, exclusivity, negative affectivity). Results indicated that the male non-participation group scored lower on all three factors and the total AIMS when compared to the two athlete groups. The male elite and recreational groups did not differ on exclusivity and negative affectivity but did differ on the total AIMS and social identity, with elite scoring higher than recreational. For female participants, the non-participation group again scored lower on all three factors and the total AIMS when compared to the two athlete groups. The female elite and recreational groups did not differ on negative affectivity but did differ on the total AIMS, social identity, and exclusivity, with elite scoring higher than recreational. Findings suggest that to assume sport is only important to elite athletes ignores the role that sport may play for less talented sport participants. Whilst not seeing themselves as athletes per se, it is suggested that participation in sport may still impact upon the self-perceptions of recreational sport participants. Therefore, threats to participation may result in similar negative consequences for both elite athletes and recreational sport participants.  相似文献   
64.
A range of 18 derivatives of flavone-8-acetic acid (FAA) with substituents on the 2-phenyl group have been prepared and their anti-tumour activity evaluated in vitro against a panel of human and murine tumour cell lines and in vivo against MAC 15A. There was no clear-cut relationship between in vitro and in vivo activity but the activity in each situation was found to be very sensitive to the precise substitution pattern with closely related isomers giving widely different activities. Some of the compounds, notably 10b,cj , and r , were active in vivo and these require further studies in order to evaluate their potential for development.  相似文献   
65.
Recent studies using a rat model of pneumococcal meningitis have shown that nitric oxide synthase (NOS) inhibitors greatly attenuated microvascular changes and brain edema formation. The site of NO production during bacterial meningitis is unknown. In this study we tested whether primary astrocyte cultures from neonatal rat cortex can be induced to release NO upon stimulation with pneumococci. NO production was assessed by measuring nitrite in the cell culture supernatant using the Griess reaction. Stimulation with heat-killed unencapsulated pneumococci (HKP) increased nitrite concentrations in astrocyte culture supernatants in a dose-dependent fashion. Administration of AT-nitro-L-arginine (L-NA), aminoguanidine, L-canavanine, cycloheximide, and dexamethasone prevented the increase in nitrite concentrations. Addition of L-arginine, but not of o-arginine, partially reversed the inhibitory effect of L-NA. Administration of SOD increased nitrite accumulation. Moreover, at 72 h after stimulation with heat-killed pneumococci (107 cfu/ml) astrocytes showed an inducible NOS-like immunoreactivity. Accumulation of nitrite was also observed when rat cerebellar neurons and microglia were stimulated with HKP, whereas there was only a slight increase of nitrite in media of rat C6 glioma cells, but no increase of nitrite when the human glioblastoma cell line LN-229 was stimulated with HKP. There was a stronger increase in nitrite levels when astrocytes from Lewis rats were used compared to that from Wistar rats. In conclusion, our study indicates that astrocytes, neurons and microglia are inducible for NO production upon stimulation with pneumococci.  相似文献   
66.
A case of actinomycotic brain infection in a juvenile patient is described. Cases of actinomycosis affecting the head and neck are rare, particularly in juvenile patients. In this case complete resolution of the infection was achieved by means of surgical treatment and prolonged antibiotic therapy. The authors emphasize the importance of a combined approach for treatment of this unusual brain infection and stress the difficulties involved in the diagnosis of this pathology. Received: 3 November 1997  相似文献   
67.
For functional rehabilitation and improvement of mandibular mobility, 14 patients with dislocated collum or collum fracture dislocations were treated with a spring activator after surgical-conservative treatment. With an interincisal distance of<12 mm, therapy was started with a loop spring. The average age of the patients was 26.6 years. Eight patients showed additional traumatic injuries, 2 patients were seriously polytraumatically injured. The clinical investigations referring to the maximum mouth opening and maximal interincisal distance resulted in a good to very good functional rehabilitation in all cases. The average maximal interincisal distance of 31.7 mm at the beginning of the spring activator therapy could be increased to 47.3 mm. The largest increase of the maximal interincisal distance was observed after 4 weeks of therapy. The type of reaction, however, differed interindividually. Three patients showed a spontaneous improvement of the interincisal distance within the first 2 to 3 weeks of removal of intermaxillary fixation, whereas 7 patients whowed no improvement or only slightly improved values until insertion of the spring activator. An enlargement of the interincisal distance could be achieved in almost every patient within a relatively short period of time despite a drastically reduced mouth opening. Consequently, because of its mode of action in the form of a neuromuscular influence, the spring activator is especially suitable for the functional rehabilitation of patients with fractures of the condylar process.  相似文献   
68.
This research presents reports of cases where a biocompatible and alloplastic biomaterial—Bioplastique—was used, associated with conventional plastic surgery or as a complement to it, with the aim of achieving a better final aesthetic result. Four cases are presented where Bioplastique was used in association with rhytidoplasty, rhinoplasty, and other surgical techniques. This material has shown itself to be appropriate to complement surgery; achieving a final result which would not be possible without any resort to a complement or any other hard procedure by the surgeon and is not more traumatic for the patient.  相似文献   
69.
70.
Summary The endoscopic insertion of self-expanding mesh stents in four patients affected by obstructing rectal malignant tumors is reported. The preliminary experience shows that, in the short term, normal defecation was achieved, with no complications. Longer follow-up is necessary to evaluate the duration and the quality of the palliative effect.  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