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   1255篇
  免费   54篇
  国内免费   147篇
耳鼻咽喉   6篇
儿科学   60篇
妇产科学   15篇
基础医学   116篇
口腔科学   18篇
临床医学   167篇
内科学   284篇
皮肤病学   33篇
神经病学   43篇
特种医学   343篇
外科学   57篇
综合类   27篇
一般理论   3篇
预防医学   38篇
眼科学   64篇
药学   115篇
  1篇
肿瘤学   66篇
  2023年   3篇
  2022年   5篇
  2021年   5篇
  2020年   4篇
  2019年   7篇
  2018年   19篇
  2017年   7篇
  2016年   8篇
  2015年   10篇
  2014年   15篇
  2013年   36篇
  2012年   13篇
  2011年   21篇
  2010年   32篇
  2009年   47篇
  2008年   28篇
  2007年   117篇
  2006年   30篇
  2005年   36篇
  2004年   15篇
  2003年   16篇
  2002年   25篇
  2001年   38篇
  2000年   24篇
  1999年   33篇
  1998年   83篇
  1997年   79篇
  1996年   72篇
  1995年   66篇
  1994年   48篇
  1993年   59篇
  1992年   11篇
  1991年   16篇
  1990年   19篇
  1989年   58篇
  1988年   37篇
  1987年   36篇
  1986年   35篇
  1985年   34篇
  1984年   21篇
  1983年   16篇
  1982年   29篇
  1981年   15篇
  1980年   14篇
  1979年   12篇
  1978年   8篇
  1977年   18篇
  1976年   35篇
  1975年   22篇
  1974年   6篇
排序方式: 共有1456条查询结果,搜索用时 15 毫秒
81.
82.
Purpose:   Magnetoencephalography (MEG)/magnetic source imaging (MSI) is a noninvasive functional neuroimaging procedure used to localize language-specific regions in the brain. The Wada test, or intracarotid amobarbital procedure (IAP), is the gold standard in determining speech/language lateralization for presurgical planning, although it is invasive and associated with morbidity. The purpose of this study is to provide further validation on the use of MSI for presurgical language lateralization by comparing results against the IAP.
Methods:   The sample consisted of 35 patients with epilepsy and/or brain tumor undergoing presurgical evaluation at the Minnesota Epilepsy Group. All patients received both an IAP and MSI to determine hemispheric language dominance. For MSI, a 148-channel MEG system was used to record activation of language-specific cortex by an auditory word-recognition task.
Results:   The MSI and IAP were concordant in determining language in the hemisphere to be treated in 86% of the cases with sensitivity and specificity values of 80% and 100%, respectively.
Conclusions:   The results from this study are consistent with prior research findings comparing functional neuroimaging procedures to the IAP in determining language lateralization in presurgical patients. The current study provides an important replication and support for Papanicolaou et al.'s findings in 2004 using a consecutive clinical sample from a different institution. An unusually high rate of atypical IAP language cases in this sample and differences between the two procedures are believed to explain the noted discrepancies. MSI is a viable noninvasive alternative to the IAP in the presurgical determination of language lateralization.  相似文献   
83.
84.
Occult fractures of the proximal femur: MR imaging   总被引:9,自引:0,他引:9  
Deutsch  AL; Mink  JH; Waxman  AD 《Radiology》1989,170(1):113
  相似文献   
85.
目的:观察核转录因子κB活性抑制剂N-乙酰半胱氨酸对脑死亡状态下巴马小型猪肾脏结构、功能与核转录因子κB mRNA其蛋白表达的影响,以期提高脑死亡供肾的肾移植效果。方法:实验于2003—08/2004—12在河南省实验动物中心及河南省病理学重点实验室完成。①实验分组及方法:将15只巴马小型猪按随机数字表法分为3组(n=5),即脑死亡组、N-乙酰半胱氨酸组及对照组。脑死亡组和N-乙酰半胱氨酸组均应用改进的缓慢间断颅内加压法建立脑死亡模型,脑死亡组不行药物干预;N-乙酰半胱氨酸组分别于初次确认脑死亡后1h,12h给予N-乙酰半胱氨酸。对照组动物麻醉后仅行开颅与开关腹手术。②实验评估:分别于首次判定脑死亡后3,6,12,18和24h检测动物血清中尿素氮、肌酐、白细胞介素1β、白细胞介素6、肿瘤坏死因子α水平。于脑死亡后3,6,12及24h开腹取相同部位肾组织,苏木精-伊红染色后观察肾组织结构变化,应用免疫组化染色观察核转录因子κB蛋白的表达水平,应用反转录-聚合酶链反应法检测核转录因子κB mRNA动态变化。结果:15只猪均进入结果分析。①自首次判定脑死亡后12h开始,脑死亡组和N-乙酰半胱氨酸组尿素氮和肌酐水平逐渐升高(P〈0.05),相同时间点比较N-乙酰半胱氨酸组显著低于脑死亡组(P〈0.05)。②自首次判定脑死亡3h开始,脑死亡组及N-乙酰半胱氨酸组白细胞介素1β、白细胞介素6、肿瘤坏死因子α逐渐升高(P〈0.05),相同时间点比较N-乙酰半胱氨酸组显著低于脑死亡组(P〈0.05)。③自脑死亡后3h开始,脑死亡组及N-乙酰半胱氨酸组肾组织NF-κB mRNA其蛋白表达水平逐渐升高(P〈0.05),相同时间点比较N-乙酰半胱氨酸组显著低于脑死亡组(P〈0.05)。④N-乙酰半胱氨酸组和脑死亡组动物脑死亡后12h可见肾脏结构变化,N-乙酰半胱氨酸组变化程度明显轻于脑死亡组。结论:N-乙酰半胱氨酸可能通过抑制核转录因子κB mRNA其蛋白的表达,减少炎症介质的释放,从而保护脑死亡状态下肾脏的功能及结构,提高脑死亡供肾肾移植效果。  相似文献   
86.
The Concorde trial compared immediate (Imm) with deferred (Def) AZT monotherapy in asymptomatic HIV-positive participants. Haematological and immunological markers and weight were measured throughout, and correlated with clinical endpoints. Markers associated with disease progression (CD4 lymphocyte count and percentage, platelets, p24 antigen and beta 2 microglobulin favoured Imm: those associated with toxicity (haemoglobin, neutrophils and white cell count) favoured Def. CD8 and total lymphocyte count did not differ significantly between groups. In multivariate analysis, the combination of baseline CD4, p24 antigen and beta 2m was the best baseline predictor of disease. Including change in CD4 and beta 2m at 12 weeks, or changes over follow- up in these markers significantly improved the fit. Markers were also incorporated into the definition of 'clinical' endpoints. Hazard ratio estimates from end-points that included CD4 < 50 and CD4 < 25 were closest to those for AIDS or death alone, but added very few extra events. Use of other landmark CD4 counts (100 or greater) or relative decreases in counts (25% or more) increased the number of events, but overestimated the effect of immediate AZT. Although AZT had a beneficial effect on the surrogate markers of efficacy evaluated, these changes did not predict clinical outcome, nor could the markers be usefully incorporated into an endpoint definition.   相似文献   
87.
True or sham plasma exchange was done weekly for 20 weeks in patients in two of the randomization groups in a prospective, blind clinical trial of experimental treatments for multiple sclerosis. Because patients could be randomized to receive sham plasma exchange and placebo medications, it was decided when the trial was designed that the use of fistulae, arteriovenous shunts, venous cutdowns, or other aggressive forms of venous access would not be permitted for any patient. Accordingly, patients judged to have inadequate superficial antecubital veins were ineligible for the trial. To date, only 13 (4.4%) of 294 patients considered for entry into the trial have been rejected on these grounds. In only 4 of the 93 patients undergoing exchange was it necessary to discontinue plasma exchange because of inadequate venous access. In 79.3 percent of the 1207 exchanges done in these patients, there were no problems of any kind with venous access. In 5.4 percent of these 1207 exchanges, it was necessary to terminate the procedure prematurely because of difficulties with patients' veins. Thus, the great majority of patients free of serious systemic illness (other than chronic progressive multiple sclerosis) can undergo weekly plasma exchange for up to 20 weeks using superficial antecubital veins without the need to resort to more invasive methods of venous access.  相似文献   
88.

Background

Relapses upon corticosteroids tapering and immunosuppressive agents are frequent in Takayasu arteritis (TA). Interleukin-6 is highly involved in physiopathology of TA. Many reports showed efficacy of tocilizumab (TCZ) in refractory TA cases. We report four cases and an updated literature review on the TCZ efficacy and safety in patients with TA.

Methods

Patients with TA defined by ACR 1990 criteria were included. Clinical, biological and imaging data were retrospectively reported. Disease activity was analyzed before TCZ and during the follow-up. Medline database was searched for systematic literature review.

Results

One hundred and five patients (median age 28 years [22–38]) were included, mostly refractory cases (76 patients, 72%). Median TCZ duration was 12 months [6–20]. Among 105 patients, 90 patients (85.7%) had an initial clinical response within three months [3–6] and 43/66 patients (65.2%) had a radiological improvement. Only seven patients (9%) showed relapse on therapy. Corticosteroid dose reduction was obtained in 75/83 patients (90.4%). Relapse after TCZ discontinuation was observed in six patients (46%), with a median time of five months [2–9]. Twenty-four side-effects were noted in 18 patients (18%), with TCZ interruption in seven cases (7%): 10 infections, five cytopenia, six hepatitis, one pancreatitis, one cutaneous rash and one breast cancer.

Conclusions

This review confirms that TCZ is safe and effective in refractory cases of TA and TCZ is a corticosteroid-sparing therapy in patients with or without previous TNFα blockers therapy. However relapses after TCZ discontinuation are frequent.  相似文献   
89.
目的:观察人工耳蜗植入术后产生听觉的最小电流值(T值)和声场主观测听阈值的变化趋势,分析可能存在的对应关系。方法:于2001-01/2004-12选择解放军第四军医大学西京医院全军耳鼻咽喉专科中心收治的接受人工耳蜗植入者20例,年龄3~6岁,无耳蜗畸形,植入后电极阻抗测试完全正常。植入者在开机后的3,6,12个月3个时间点调机和声场测听。人工耳蜗调试采用澳大利亚Cochlear公司提供的调试软件R126 V2.1,采用游戏行为测听法确定T值。对开机后3,6,12个月的声场主观测听阈值与人工耳蜗调试中T值的变化进行分析。结果:声场测听阈值在开机12个月中呈逐渐降低趋势,开机12个月时声场测听的听力水平较3个月和6个月有明显提高(P<0.05)。植入者术后12个月声场主观测听(啭音)听阈为15~35dB nHL,听力水平较术前有明显提高。20例植入者T值在开机12个月后降到144~158mA,明显低于6个月和3个月的水平(P<0.05)。结论:开机后12个月内产生听觉的最小电流值和声场测听阈值都呈逐渐下降趋势。植入者在熟悉适应了电声信号后,可以在刺激电流强度下降的同时获得更好的听力水平。  相似文献   
90.
In apparently localized amyloidosis, there is no appropriate test to determine whether systemic deposits exist. We studied the value of serum amyloid P component (SAP) scintigraphy and labial salivary gland (LSG) biopsy on patients with apparently localized amyloidosis in 12 patients who had neither clinical nor biological evidence of systemic amyloidosis. All patients had an LSG biopsy and echocardiography. Iodine-123-labelled serum amyloid P component (123I-SAP) scintigraphy was performed in all patients. Whole-body scintigraphy was done, and tissue retention was evaluated at 24 h and 48 h. Of these 12 patients, three had amyloidosis in their LSG and had abnormal 123I-SAP scintigraphy; these three had a secondary clinical history of systemic amyloidosis. Three other patients had abnormal 123I-SAP scintigraphy without detectable systemic amyloid deposits, but one had a previous history of bilateral carpal tunnel syndrome treated with infiltration. 123I-SAP scintigraphy in association with LSG biopsy may be helpful in determining the localized or systemic character of amyloid disease.   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