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   711955篇
  免费   49131篇
  国内免费   1345篇
耳鼻咽喉   9219篇
儿科学   23339篇
妇产科学   17685篇
基础医学   111121篇
口腔科学   20222篇
临床医学   64111篇
内科学   135983篇
皮肤病学   16221篇
神经病学   49803篇
特种医学   25842篇
外国民族医学   76篇
外科学   105577篇
综合类   14860篇
现状与发展   2篇
一般理论   160篇
预防医学   51535篇
眼科学   16431篇
药学   54592篇
  3篇
中国医学   2381篇
肿瘤学   43268篇
  2021年   5540篇
  2018年   7964篇
  2017年   6187篇
  2016年   6908篇
  2015年   7627篇
  2014年   10371篇
  2013年   15523篇
  2012年   20754篇
  2011年   21729篇
  2010年   12850篇
  2009年   12044篇
  2008年   20208篇
  2007年   21789篇
  2006年   22151篇
  2005年   20709篇
  2004年   20242篇
  2003年   19166篇
  2002年   18720篇
  2001年   36500篇
  2000年   37105篇
  1999年   30569篇
  1998年   7956篇
  1997年   6724篇
  1996年   7034篇
  1995年   6701篇
  1994年   6140篇
  1993年   5633篇
  1992年   23136篇
  1991年   23062篇
  1990年   22438篇
  1989年   22225篇
  1988年   20170篇
  1987年   19540篇
  1986年   18582篇
  1985年   17427篇
  1984年   12785篇
  1983年   10819篇
  1982年   5976篇
  1979年   11589篇
  1978年   8183篇
  1977年   6880篇
  1976年   6644篇
  1975年   7301篇
  1974年   8552篇
  1973年   8186篇
  1972年   7706篇
  1971年   7162篇
  1970年   6919篇
  1969年   6363篇
  1968年   5819篇
排序方式: 共有10000条查询结果,搜索用时 93 毫秒
991.
The frequency and complications of respiratory viral infections (RVI) were studied in 50 ambulatory lung transplant patients during a single winter season, using viral antigens, viral cultures and PCR of nasal washes or bronchoalveolar lavages. Patients' survival, episodes of acute rejection and occurrence of bronchiolitis obliterans (BO) or BO syndrome (BOS) were monitored for 1 yr after the study. Overall, 32 (64%) patients had 49 symptomatic episodes. Documented infections included eight due to respiratory syncytial virus (RSV), one due to parainfluenza virus (PIV) and 10 due to influenza (FLU). Four of the FLU infections were serological rises without symptoms. Overall, 17 (34%) patients had documented viral infection; four patients had lower respiratory involvement and two (one RSV, one PIV) were hospitalised for aerosolised ribavirin treatment. After 1 yr there were three (6%) deaths unrelated to RVI. BO or BOS had occurred in one (6%) out of 17 patients with and three (12%) out of 33 without RVI. Respiratory viruses infected one-third of ambulatory lung transplant recipients in a single season. In conclusion, respiratory viral infection was not associated with subsequent graft dysfunction. Larger prospective studies are required to better define the acute and long-term morbidity of these infections.  相似文献   
992.
Linear atrophoderma of Moulin has a distinctive disease pattern characterized by hyperpigmented atrophoderma and was described originally in 1992. It follows the line of Blaschko, and occurs without preceding inflammation, subsequent induration or scleroderma. The lesions usually develop during childhood or adolescence, and the prognosis is good. The diagnosis is made clinically and histopathologically. In our 18-year-old male patient, there were atrophic plaques unilaterally located on the trunk and arm, and white discoloration on all finger nails. Histopathological examination revealed epidermal atrophy together with disruption of collagen fibres.  相似文献   
993.
994.
995.
BACKGROUND: Activation recovery intervals (ARIs) and monophasic action potential (MAP) duration are used as measures of action potential duration in beating hearts. However, controversies exist concerning the correct way to record MAPs or calculate ARIs. We have addressed these issues experimentally. OBJECTIVES: To experimentally address the controversies concerning the correct way to record MAPs or calculate ARIs. METHODS: Left ventricular local electrograms were recorded in isolated pig hearts with an exploring electrode grid, with a KCl reference electrode on the left ventricular myocardium, the aortic root, or the left atrium. Local activation was determined from calculated Laplacian electrograms. RESULTS: With the KCl electrode on the aortic root, local electrograms represented local activation. However, with the KCl electrode on the myocardium remote from the exploring electrode, a combined electrogram emerged consisting of local activation recorded from the grid and remote activation recorded from the reference electrode. The remote, inverted monophasic component did not show propagation and did not correlate with the Laplacian complex. When the KCl electrode was placed on the atrium during AV block, remote atrial monophasic components were completely dissociated from local, ventricular deflections. At left ventricular sites with a positive T wave, the Laplacian signal showed that the end of the T wave was caused by remote repolarization. During cooling-induced regional action potential prolongation, the T wave became negative, whereby the positive flank of the T wave remained correlated with repolarization (recorded with a MAP at the same site). CONCLUSIONS: MAPs are recorded from the depolarizing electrode. In both negative and positive T waves, the moment of maximum dV/dt corresponds to local repolarization.  相似文献   
996.
Evaluation of the thyroid nodule.   总被引:3,自引:0,他引:3  
BACKGROUND: Thyroid nodules are common, yet treatment modalities range from observation to surgical resection. Because thyroid nodules are frequently found incidentally during routine physical examination or imaging performed for another reason, physicians from a diverse range of specialties encounter thyroid nodules. Clinical decision making depends on proper evaluation of the thyroid nodule. METHODS: The current literature was reviewed and synthesized. RESULTS: Current evidence allows the formulation of recommendations and a general algorithm for evaluating the incidental thyroid nodule. CONCLUSIONS: Only a small percentage of thyroid nodules require surgical management. Diagnosis and treatment selection require a risk stratification by history, physical examination, and ancillary tests. Nodules causing airway compression or those at high risk for carcinoma should prompt evaluation for surgical treatment. In nodules larger than 1 cm, fine-needle aspiration biopsy is central to the evaluation as it is accurate, low risk, and cost effective. Subcentimeter nodules, often found incidentally on imaging obtained for another purpose, can usually be evaluated by ultrasonography. Other laboratory and imaging evaluations have specific and more limited roles. An algorithm for the evaluation of the thyroid nodule is presented.  相似文献   
997.
The antiproliferative effect of As(2)O(3)-loaded microemulsion (As(2)O(3)-M) on human MDAH 2774 ovarian cancer cells was compared with a regular solution of the As(2)O(3). We used MDAH 2774 as model cell lines for ovarian cancer. The (2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-5-[(phenylamino)carbonyl]-2H-tetrazolium hydroxide) (XTT) and trypane blue dye exclusion tests were used to evaluate cytotoxicity. Apoptotic effect of solutions was evaluated using cell death detection kit. Standard microemulsion formulation used in this experiment contains 5 x 10(-6) M As(2)O(3). It was clearly demonstrated that As(2)O(3)-M had a significant cytotoxic effect on MDAH 2774 cell line, and the cytotoxic effect of As(2)O(3)-M was significantly higher than that of regular As(2)O(3) solutions. Even approximately 6000 times diluted microemulsion formulation loaded with 5 x 10(-6) M As(2)O(3) showed a cytotoxic effect. As a result, this diluted concentration (approximately 8 x 10(-10) M) was found to be approximately 6000 times more effective than regular As(2)O(3) solutions (5 x 10(-6) M). Moreover, this diluted concentration resulted in 1.5-fold enhancement of apoptosis. According to the in vitro cytotoxicity studies, we concluded that by incorporating As(2)O(3) into the microemulsion (As(2)O(3)-M), which is a new drug carrier system, it is possible to increase antiproliferative effect of regular As(2)O(3) on MDAH 2774 cells. Translating these results to in vivo conditions would open new windows in the treatment of ovarian cancer.  相似文献   
998.
999.
We report a 40-year-old man with rheumatic heart disease who presented with abdominal pain for three weeks and hematemesis for 24 hours. CT scan showed a large splenic artery aneurysm without evidence of pancreatitis. Mycotic aneurysm due to infective endocarditis was considered and confirmed by echocardiogram, which showed aortic and mitral valve regurgitation and vegetations. He was managed successfully with coil embolization of the aneurysm and antibiotics.  相似文献   
1000.
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