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   1494篇
  免费   83篇
  国内免费   21篇
耳鼻咽喉   94篇
儿科学   58篇
妇产科学   19篇
基础医学   205篇
口腔科学   20篇
临床医学   97篇
内科学   295篇
皮肤病学   22篇
神经病学   127篇
特种医学   66篇
外科学   261篇
综合类   22篇
预防医学   64篇
眼科学   115篇
药学   59篇
肿瘤学   74篇
  2021年   14篇
  2020年   13篇
  2019年   15篇
  2018年   17篇
  2017年   12篇
  2016年   14篇
  2015年   9篇
  2014年   31篇
  2013年   55篇
  2012年   61篇
  2011年   53篇
  2010年   45篇
  2009年   49篇
  2008年   54篇
  2007年   59篇
  2006年   70篇
  2005年   79篇
  2004年   68篇
  2003年   65篇
  2002年   59篇
  2001年   50篇
  2000年   52篇
  1999年   42篇
  1998年   22篇
  1997年   31篇
  1996年   31篇
  1995年   28篇
  1994年   18篇
  1993年   22篇
  1992年   36篇
  1991年   28篇
  1990年   19篇
  1989年   31篇
  1988年   26篇
  1987年   29篇
  1986年   25篇
  1985年   24篇
  1984年   24篇
  1983年   18篇
  1982年   16篇
  1980年   9篇
  1979年   23篇
  1978年   13篇
  1976年   12篇
  1972年   10篇
  1971年   10篇
  1970年   17篇
  1969年   9篇
  1968年   10篇
  1965年   9篇
排序方式: 共有1598条查询结果,搜索用时 15 毫秒
11.
BACKGROUND: Short-term discontinuation of psychiatric medications is required in many types of research studies. Yet there are few studies of the clinical impact of psychotropic discontinuation. We studied the impact of a short-term medication washout in unipolar depressed patients consecutively admitted to hospital for neuroimaging and cerebrospinal fluid (CSF) studies. METHOD: Patients (n=51) with unipolar depression who were taking antidepressant or mood stabilizing medication at or within 1 week of admission, and who had not been responding satisfactorily, were assessed for severity of psychopathology within 1 week of hospital admission and 41 of the group were reassessed following an approximately 2-week medication washout. RESULTS: On average, patients remained stable during the washout or improved on clinical measures. No serious adverse clinical changes were observed. LIMITATIONS: Potential sample bias, small sample size. CONCLUSION: The results suggest that similar studies can be conducted without causing undue worsening of symptoms. The benefit of medication washout may be related to the fact that many of the patients had been responding poorly to the medication they were taking. There is a need for further research on the effects of medication washout, for example in outpatients or those who are responding well to treatment, but have intolerable side-effects.  相似文献   
12.
13.
14.
Human milk oligosaccharides are known to play a role in protection against certain infectious diseases. Previous reports indicate that the content of human milk oligosaccharides varies widely among individuals at term but such information on preterm milk is lacking. After removal of the fat, protein and most of the lactose from non-pooled human milk samples, a total neutral oligosaccharide fraction was isolated by ion-exchange chromatography followed by gel filtration. A Dionex high-performance anion-exchange chromatography system equipped with a pulsed electrometric detector was then employed to measure the levels of ten neutral oligosaccharides in the individual milk samples. Twenty-three milk samples from thirteen mothers who delivered at a mean gestational age of 29.5 (SD 3.1) weeks were collected between days 0 and 33 of lactation, and compared with three samples of term milk from two mothers. The ranges of the total and individual levels of the ten neutral oligosaccharides in preterm milk were similar to those in term milk. Further, as previously described in term milk, preterm milk exhibited a quantitative individual variation. This variation was independent of the gestational age, day of lactation, and postconceptional age. In conclusion, levels of ten neutral oligosaccharides did not differ between preterm and term human milk.  相似文献   
15.
PURPOSE: To determine whether posterior pituitary ectopia in children with optic nerve hypoplasia has a male predominance or an increased incidence of breech delivery. METHOD: Retrospective analysis of 12 children with optic nerve hypoplasia and posterior pituitary ectopia. RESULTS: Eleven of 12 patients with posterior pituitary ectopia were boys. No child had a history of breech delivery. Two children had a history of breech positioning but were delivered by cesarean section. CONCLUSION: Posterior pituitary ectopia with optic nerve hypoplasia shows a strong male predominance but no association with breech delivery.  相似文献   
16.
R A Brodsky  R J Jones 《Leukemia》2004,18(10):1740-1742
Secondary myelodysplastic syndrome (MDS)/acute leukemia frequently evolves from severe aplastic anemia (SAA) following immunosuppressive therapy. Secondary clonal cytogenetic abnormalities have now been reported after noncytotoxic therapy in two additional settings: all trans retinoic acid (ATRA) treatment of acute promyelocytic leukemia (APL) and imatinib for chronic myeloid leukemia (CML). We propose that SAA, APL, CML, and MDS represent different manifestations of generalized insults to the bone marrow. In SAA, the insult to hematopoietic progenitors leads to an immune attack, while in APL, CML, and MDS, it gives rise to the malignant clones. A primary insult to bone marrow could simultaneously lead to several abnormal hematopoietic cell clones, with one dominating and the others present but below the level of detection. Such a 'field leukemogenic effect' would be analogous to the 'field cancerization effect' described in solid tumors. Nonspecific cytotoxic therapies, including antileukemic chemotherapy and allogeneic transplantation, have broad activity that could inhibit both the overt disease and other undetectable coexistent abnormal clones. In contrast, disease-specific targeted therapy such as immunosuppressive therapy in aplastic anemia, ATRA in APL, or imatinib in CML would have no activity against other abnormal clones, allowing them to expand and become detectable as the dominant clone declines.  相似文献   
17.
Evaluation of all 153 children undergoing CT scan of the paranasal sinuses for recalcitrant sinusitis symptoms between January 1988 and July 1992 was performed. Clinical categorization into groups of patients presenting with chronic sinusitis (CS) and recurrent acute sinusitis (RAS) was based upon pattern of disease and presentation. Clinical symptoms and signs, radiological examination, treatment, and outcome were compared between these distinct clinical groups. Eighty-two (55%) children were categorized as RAS and 68 (45%) as CS. Children with CS presented more frequently with a persistent cough, purulent nasal discharge, immune deficiency, and more severe mucosal disease on CT than children with RAS. Medical therapy successfully controlled the symptoms of sinusitis in 79 (96%) with RAS versus 27 (40%) with CS. Surgery was performed in 44 children: 3 (3.6%) with RAS versus 41 (60%) with CS, p<0.01. At a mean follow-up of 2.0 years, >80% of all the children were either asymptomatic or improved regardless of treatment modality. These data support the use of clinical classification as a guide to medical versus surgical therapy in children with sinusitis.  相似文献   
18.
This review correlates the imaging findings and histological appearances seen in chordomas in a series of patients presenting at our institution, together with a published literature review. A parallel presentation of photographs of imaging findings and microscopic histological findings is made, with the aim being to enhance recognition of this uncommon but clinically significant entity.  相似文献   
19.
Sulfur mustard (SM) is a powerful vesicant employed as an agent of chemical warfare. This study demonstrates the therapeutic effect of a novel topical iodine preparation as a postexposure treatment against SM-induced lesions in the fur-covered guinea-pig skin model. Iodine treatment 15 min after SM exposure resulted in statistically significant reductions of 48, 50, and 55% in dermal acute inflammation, hemorrhage, and necrosis, respectively, whereas, the epidermal healing markers, hyperkerathosis and acanthosis, were significantly elevated by 72 and 67%, respectively, 2 days after treatment. At the interval of 30 min between SM exposure and iodine treatment, there was a significant degree of healing or recovery, albeit to a lesser extent than that observed in the shorter interval. Although the epidermal healing markers were not elevated, the parameters indicative of active tissue damage, such as subepidermal microblisters, epidermal ulceration, dermal acute inflammation, hemorrhage, and necrosis, were significantly reduced by 35, 67, 43, 39, and 45%, respectively. At the 45-min interval between exposure and treatment, there was also a certain degree of healing or recovery expressed as significant reductions in dermal subacute inflammation, subepidermal microblister formation, and epidermal ulceration, whereas, acanthosis was statistically elevated, indicating an increased healing potential. At the 60-min interval, iodine was less efficacious; nevertheless, a significant reduction in the incidence of subepidermal microblisters and an expansion of the acanthotic area were observed. Gross ulceration was significantly decreased at intervals of 15 and 30 min between exposure and treatment. The local anesthetic, lidocaine, did not alter the therapeutic effect of iodine. SM was not affected chemically by iodine as measured by gas chromatography-mass spectrometry (GC-MS) analysis. These findings suggest that the iodine preparation functions as an antidote against skin lesions induced by SM.  相似文献   
20.
Twenty-four premature fetal lambs underwent tracheotomy (n = 11) or endotracheal intubation (n = 13) for 3-9 h for an unrelated experiment. All were maintained with 100% oxygen on a pressure cycled ventilator. No suctioning was performed. At sacrifice, sections of the distal trachea were studied for histopathological changes in epithelium, submucosa and mucous glands. All changes were confined to the epithelium and were reported as either partial or total epithelial erosion in regards to preservation of the basal cell layer. In tracheotomized and intubated animals, both partial and total erosion were seen as early as 3 and 3.5 h, respectively. In the intubated animals, 13.5% of the cumulative tracheal circumference showed total erosion; 19.8% showed partial erosion. In animals undergoing tracheotomy, 9.6% of the cumulative tracheal circumference had total erosion; 19.1% had partial erosion. Possible etiological factors include oxygen toxicity, lack of humidification, effects of mechanical ventilation and indirect trauma from surgery or intubation. The clinical significance for premature infants is discussed.  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