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   2392篇
  免费   171篇
  国内免费   25篇
耳鼻咽喉   17篇
儿科学   142篇
妇产科学   16篇
基础医学   345篇
口腔科学   160篇
临床医学   231篇
内科学   409篇
皮肤病学   67篇
神经病学   211篇
特种医学   295篇
外科学   228篇
综合类   32篇
预防医学   126篇
眼科学   37篇
药学   106篇
  1篇
中国医学   3篇
肿瘤学   162篇
  2023年   12篇
  2022年   16篇
  2021年   18篇
  2020年   24篇
  2019年   36篇
  2018年   37篇
  2017年   30篇
  2016年   34篇
  2015年   52篇
  2014年   57篇
  2013年   113篇
  2012年   101篇
  2011年   89篇
  2010年   95篇
  2009年   97篇
  2008年   79篇
  2007年   92篇
  2006年   73篇
  2005年   83篇
  2004年   73篇
  2003年   79篇
  2002年   73篇
  2001年   71篇
  2000年   65篇
  1999年   65篇
  1998年   98篇
  1997年   89篇
  1996年   79篇
  1995年   63篇
  1994年   46篇
  1993年   50篇
  1992年   28篇
  1991年   47篇
  1990年   45篇
  1989年   62篇
  1988年   54篇
  1987年   42篇
  1986年   31篇
  1985年   36篇
  1984年   26篇
  1983年   28篇
  1982年   19篇
  1981年   19篇
  1980年   16篇
  1978年   23篇
  1977年   23篇
  1976年   13篇
  1975年   13篇
  1974年   11篇
  1973年   12篇
排序方式: 共有2588条查询结果,搜索用时 46 毫秒
21.
22.
23.
BACKGROUND: Acquired cerebriform intradermal naevus (CIN) is a rare form of pseudo cutis verticis gyrata. CASE REPORT: A case of acquired CIN of the scalp in a 46-year-old male patient is presented. The clinical and histopathological presentations of CIN are described and the therapeutic possibilities are discussed. CONCLUSIONS: In each individual case the physician must decide whether to do surgery or follow a wait-and-see policy. There is little risk of malignant change of CIN, and surgical excision of such lesions often involves evident mutilation.  相似文献   
24.
OBJECTIVE: The authors evaluated the risk of necrotizing enterocolitis (NEC) in very low birth weight infants receiving indomethacin (INDO) to close patent ductus arteriosus (PDA). BACKGROUND DATA: Controversy exists regarding the best method of managing very low birth weight infants with PDA and whether to employ medical management using INDO or surgical ligation of the ductus. METHODS: Two hundred fifty-two premature infants with symptomatic PDA were given intravenously INDO 0.2 mg/kg every 12 hours x 3 in an attempt to close the ductus. Patients were evaluated for sex, birth weight, gestational age, ductus closure, occurrence of NEC, bowel perforation, and mortality. RESULTS: There were 135 boys and 117 girls. The PDA closed or became asymptomatic in 224 cases (89%), whereas 28 (11%) required surgical ligation. Ninety infants (35%) developed evidence of NEC after INDO therapy. Fifty-six were managed medically; surgical intervention was required in 34 of 90 cases (37.8%) or 13% of the entire PDA/INDO study group. Bowel perforation was noted in 27 cases (30%). Factors associated with the onset of NEC included gestational age < 28 weeks, birth weight < 1 kg, and prolonged ventilator support. The overall mortality rate was 25.5%, but was higher in infants with NEC versus those without. The highest mortality was noted in perforated NEC cases. The PDA/INDO patients were compared with a control group of 764 infants with similar sex distribution, birth weights, and gestational ages without PDA who did not receive INDO. Necrotizing enterocolitis occurred in 105 of 764 control patients (13.7%), including 13 (12.3%) with perforation. The overall mortality rate of controls was 25%, which was similar to the overall 25.5% mortality rate in the PDA/INDO study group. CONCLUSION: These data indicate that there is increased risk of NEC and bowel perforation in premature infants with PDA receiving INDO. Mortality was higher in the PDA/INDO group with NEC than those PDA/INDO infants without NEC.  相似文献   
25.
Communication of infection-control practices is an overlooked area of practice management. Often, people forget to consider the training, time, and expense associated with the wide variety of protocols, techniques, and regimens. Explore and develop approaches aimed at conveying the infection-control practices you use to other care providers and your patient family. When these are used appropriately, you serve both patients and the community in the capacity for which you were trained--as a health-care professional. It does not get any better than that!  相似文献   
26.
Objective: Right upper lobe collapse is a common radiographic finding in intubated children. We hypothesized that deep suctioning and uncontrolled negative pressures during endotracheal tube suctioning were significant contributory factors. Methods : The incidence of right upper lobe (RUL) collapse in intubated, ventilated children on a paediatric cardiac intensive care unit was determined over a 3-month period ( n = 102). Graduated suction catheters and suction vacuums of < 165 cm H2O were then introduced. Another prospective audit was carried out 3 months later ( n = 60). Results : We found that 24% developed RUL collapse and 4 developed an apical pneumothorax. Following the introduction of graduated catheters and controlled vacuums pressures, a significant reduction in the incidence of RUL collapse, to 7%, was observed ( p < 0.05). Conclusions : We conclude that high negative pressure and deep-suctioning causes RUL collapse in children. Any lobar collapse not only prolongs the child's stay in intensive care, but can be associated with further morbidity which may have a serious implication. By improving suctioning technique this morbidity can be significantly reduced.  相似文献   
27.
Secondary generalized epilepsy in childhood, characterized by absences or minor motor seizures, occurs in the forms of various syndromes, as defined by current classifications. EEG often shows continuous or subcontinuous paroxysmal activity associated with partly reversible psychomotor or mental regression. The paroxysmal activity can exhibit one of two distinct patterns: "organized" or "disorganized," although intermediate forms are common. The two patterns differ not only morphologically but also in the responsiveness to drug or hormone therapy, reactivity to stimuli, sleep changes and frequency of disordered slow rhythms. These features are illustrated by means of a survey of 10 cases.  相似文献   
28.
Septo-optic dysplasia: MR imaging   总被引:5,自引:0,他引:5  
Barkovich  AJ; Fram  EK; Norman  D 《Radiology》1989,171(1):189-192
Septo-optic dysplasia is the diagnosis when optic nerve hypoplasia is seen in conjunction with dysgenesis of the septum pellucidum. Nearly two-thirds of these patients have hypothalamic-pituitary dysfunction, and half have schizencephaly. The disorder is difficult to classify because of the diversity of clinical and pathologic manifestations. Magnetic resonance images of 11 patients with clinical and radiographic evidence of septo-optic dysplasia were reviewed retrospectively. The "syndrome" appears to include two subsets of patients whose abnormalities have different embryogenesis and neuropathologic findings. The existence of these two subsets helps to explain the diversity of the clinical and radiologic findings.  相似文献   
29.
Recombination of deltaRec to psiJalpha will delete the TCR delta gene, which is thought to play an important role in the bifurcation of the TCR alphabeta versus TCR gammadelta differentiation lineages. We recently detected a DNA-binding protein in human thymocytes, the so- called PJA-BP, which recognizes the psiJalpha gene segment and might be one of the factors involved in the regulation of preferential deltaRec- psiJalpha rearrangements. We now investigate PJA-BP expression and its correlation with TCR delta gene deletion in thymocytes. Our electrophoretic mobility shift assay experiments showed that the PJA-BP is evolutionary conserved in human, murine and simian thymocytes. Using a large series of human hematopoietic malignancies (n = 30), we conclude that PJA-BP expression is thymocyte specific and seems to be restricted to thymocytes committed to the TCR alphabeta lineage. Analysis of seven well-defined human thymocyte subpopulations showed that preferential deltaRec-psiJalpha rearrangements as well as PJA-BP expression can be detected from the immature CD34-/CD1+/CD3- /CD4+/CD8alpha+beta- thymocyte differentiation stage onwards. These experiments indicate that expression of PJA-BP in human thymocytes starts simultaneously with preferential deltaRec-psiJalpha rearrangements, which supports our hypothesis that PJA-BP is one of the factors involved in the preferential recombination of deltaRec to psiJalpha.   相似文献   
30.
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