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   16955篇
  免费   660篇
  国内免费   75篇
耳鼻咽喉   534篇
儿科学   1528篇
妇产科学   584篇
基础医学   1002篇
口腔科学   1034篇
临床医学   1207篇
内科学   3025篇
皮肤病学   435篇
神经病学   997篇
特种医学   810篇
外科学   3720篇
综合类   341篇
一般理论   7篇
预防医学   503篇
眼科学   541篇
药学   899篇
中国医学   96篇
肿瘤学   427篇
  2024年   18篇
  2023年   185篇
  2022年   202篇
  2021年   350篇
  2020年   270篇
  2019年   318篇
  2018年   459篇
  2017年   401篇
  2016年   490篇
  2015年   433篇
  2014年   603篇
  2013年   835篇
  2012年   990篇
  2011年   1018篇
  2010年   562篇
  2009年   401篇
  2008年   861篇
  2007年   985篇
  2006年   997篇
  2005年   1038篇
  2004年   1100篇
  2003年   1026篇
  2002年   997篇
  2001年   678篇
  2000年   598篇
  1999年   515篇
  1998年   188篇
  1997年   154篇
  1996年   160篇
  1995年   80篇
  1994年   70篇
  1993年   54篇
  1992年   96篇
  1991年   88篇
  1990年   72篇
  1989年   73篇
  1988年   40篇
  1987年   32篇
  1986年   34篇
  1985年   35篇
  1984年   30篇
  1983年   16篇
  1982年   10篇
  1981年   14篇
  1979年   14篇
  1978年   10篇
  1976年   9篇
  1972年   11篇
  1971年   8篇
  1966年   8篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
82.
A 14-year-old boy had a 1-month history of diplopia (due to a VI nerve palsy), motor ataxia and dizziness. Brain MRI showed a 1.5-cm mass posterior to the pons. Histopathological examination of a biopsy specimen showed the lesion to be of viral origin. After 3 months, the ataxia and dizziness had resolved and the MRI findings returned to normal. By 5 months the abducens paralysis had also resolved. Viral encephalitis should be considered in the differential diagnosis of posterior fossa tumours. Received: 20 March 1997 Accepted: 16 April 1997  相似文献   
83.
The role of sigmoidoscopic examination in the diagnosis, evaluation, and treatment of minor lower gastrointestinal bleeding was investigated. A hundred patients with minor rectal bleeding were examined by rigid sigmoidoscopy under general anaesthesia between January 1989 and July 1996. Patients who had bleeding secondary to infections, anal fissure, or haemorrhoids were excluded from study. Patients were reviewed retrospectively according to their diagnosis and endoscopic and histopathological findings. Twenty nine of these patients were girls and 71 boys; their ages ranged between 8 month and 14 years (mean 7.2 years). Endoscopic pathological findings were established in 60 patients; 32 had rectal polyps, 16 non-specific proctitis, four solitary rectal ulcers, three internal haemorrhoids, two ulcerative colitis, two Hirschsprung's enterocolitis, and one haemangioma. It is concluded that sigmoidoscopic examination should be performed for the diagnosis, prognosis, and choice of treatment in patients with minor rectal bleeding and the diagnosis should be confirmed histopathologically.  相似文献   
84.
85.
Summary ? Background. Cerebral vasospasm after subarachnoid hemorrhage (SAH) has remained a major cause of morbidity and mortality in patients with SAH. Excitatory neurotransmitters are gathered in the extracellular space during ischemia due to cerebral vasospasm and initiate or stimulate a series of pathophysiological biochemical processes which consequently lead to neuronal death. Tizanidine (Sandoz compound DS 103–282, 5-chloro-4,2 (2-imidazolin-2-yl-amino)-2,1,3-benzothiazol hydrochloride) is a centrally-acting muscle relaxant and a selective α 2 adrenoreceptor agonist which shows its effect by stimulating presynaptic α 2 adrenoreceptors in central ASPergic and GLUergic system by inhibiting aspartic acid and glutamic acid release. In this study, the effect of Tizanidine on vasospasm was evaluated.  Methods. We used a femoral artery vasospasm model in rats which has been described by Okada et al. 60 rats were examined in three groups. The first group was used as control group (Control) (n=20), in the second group subarachnoid hemorrhage was performed (SAH) (n=20), in the third group Tizanidine was administered in addition to SAH (SAH+Tizanidine administration) (n=20). Animals in SAH+Tizanidine administration group received 0,3 mg/kg/day intraperitoneally for 7 days. Seven days after the experiment, after perfusion-fixation, 10 mm segments of both femoral arteries were removed and the femoral artery was prepared for light microscope examination, scanning and transmission electron microscopy and for morphometric analysis.  Results. There was a statistically significant difference between the electron, scanning and light microscopic observations and morphometric analysis of SAH+Tizanidine administration group and SAH group, and no statistically significant difference between SAH+Tizanidine administration group and control group.  Conclusion. This study has disclosed that Tizanidine administration before the vasospasm reduces ultrastructural and morphometric vasospastic insult significantly. However, the clinical application of Tizanidine as a protective and therapeutic agent in cerebral vasospasm needs further studies including the employment of clinically more relevant SAH models.  相似文献   
86.
Mesoatrial shunt in Budd-Chiari syndrome   总被引:2,自引:0,他引:2  
BACKGROUND: The operations with proven effects on survival in Budd-Chiari syndrome are shunt operations and liver transplantation. PATIENTS AND METHODS: Between 1993 and 1999 (June), 13 cases of Budd-Chiari syndrome have been treated surgically. Four cases had concomitant thrombosis of the inferior vena cava; the others had marked narrowing of the lumen due to the enlarged caudate lobe. Mesoatrial (n = 12) or mesosuperior vena caval (n = 1) shunts were constructed with ringed polytetrafluoroethylene grafts. RESULTS: The median portal pressure fell from 45 (range 32 to 55) to 20 (range 11 to 27) cm H(2)O (P <0.001). Two patients died in the early postoperative period. One patient who did not comply with anticoagulant treatment had a shunt thrombosis in the second postoperative year. The other 10 patients are alive without problems during a median 42 (range 1 to 76) months of follow-up. CONCLUSION: Mesoatrial shunt with a ringed polytetrafluoroethylene graft is effective in Budd-Chiari syndrome cases with thrombosis or significant stenosis in the inferior vena cava.  相似文献   
87.
BACKGROUND: Nitric oxide (NO) may have an important role in the healing of burn wounds. This study investigated the effect of NO on experimentally induced burn wounds by preventing NO synthesis. METHODS: A total of 40 mice weighing 25 to 30 g were used in this study. The shaved skin on the back of the mice was immersed in 100 degrees C water for 10 seconds to achieve a partial-thickness scald burn. The mice were divided into two groups of 20. In group I (control group), 17.5 mg/kg of serum physiologic (placebo) was injected intraperitoneally two times a day for 15 days. In group II (study group), 17.5 mg/kg of aminoguanidine (NO synthase inhibitor) was injected intraperitoneally two times a day for 15 days. On day 15 of the burn, the animals were killed and the burn areas were investigated histologically. Histologic changes such as epithelial proliferation, abscess, collagen, and granulation tissue were evaluated. RESULTS: Epithelial proliferation, formation of collagen, and granulation tissue with rich capillaries observed in the control group were statically significantly higher than those observed in the study group (z = -2.022, p < 0.05; z = -2.02, p < 0.05; and z = -2.022, p < 0.05; respectively). CONCLUSION: We concluded that healing of the burn wound is delayed by preventing NO synthesis.  相似文献   
88.
BACKGROUND: Ependymomas, the common glial tumors of the spinal cord, occur occasionally outside the central nervous system and are called exstraspinal ependymomas (EEP). EEPs are found primarily in sacrococcygeal region during childhood. The pathogenesis and the treatment of the sacrococcygeal (SC) ependymomas are still controversial. Therefore, we present our case with metaanalysis of other case reports to determine the optimal treatment modality for SC EEPs. METHODS: A metaanalysis of case reports of SC EEPs, including the current case, was conducted. Also all available case reports of EEPs, without age limit, were analyzed to determine the distribution of EEPs localization. RESULTS: EEPs usually are found in teratoma localizations such as the SC area, ovary, paraovarian structures, and medastinum. The distribution of EEPs localization differs with age. Local recurrence rate of EEPs after coccyx excision is zero, however, it increases to 71% when the coccyx was left behind. CONCLUSION: The identical clinical characteristics of the SC teratomas and EEPs imply that the SC EEPs may be monophasic teratomas as their ovarian counterparts are named. Coccyx excision is an important part of the surgical treatment of these tumors, with an apparent decrease in the recurrence rate.  相似文献   
89.
90.
OBJECTIVE: The purpose of this study was to determine the reliability of the vaginal washing-fluid prolactin assay for the diagnosis of premature rupture of membranes (PROM) and to determine a diagnostic cut-off value. STUDY DESIGN: Seventy pregnant women between 11 and 40 weeks of gestation who were admitted with vaginal fluid leakage were included in the study group, and were then further subdivided into two subgroups according to amniotic fluid pooling and nitrazine paper test results. Group 1 was the 'confirmed PROM group', positive for both pooling and nitrazine (38 patients). Group 2 was the 'suspected but unconfirmed PROM group' which had possible pooling and/or nitrazine (32 patients). Seventy pregnant women between 11 and 40 weeks of gestation without any complaint and complication were included in the control group (group 3). All patients underwent vaginal washing-fluid sampling and prolactin level determination. For the statistical analysis one-way analysis of variance, Tukey multiple comparison test, chi2 test and receiver operating characteristic (ROC) curve analysis were used. RESULTS: Geometric mean values of vaginal washing-fluid prolactin levels were 616.59 microIU/ml for group 1, 23.98 microIU/ml for group 2 and 10 microIU/ml for group 3 (p < 0.0001). The optimal diagnostic cut-off value was found to be 30 microIU/ml with 95% sensitivity, 78% specificity, 84% positive predictive value, 93% negative predictive value, 87% accuracy and 11.30 relative risk. CONCLUSIONS: We recommend vaginal washing-fluid prolactin level determination as an alternative diagnostic method for PROM.  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