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   1728篇
  免费   131篇
  国内免费   48篇
耳鼻咽喉   8篇
儿科学   172篇
妇产科学   87篇
基础医学   234篇
口腔科学   49篇
临床医学   215篇
内科学   327篇
皮肤病学   32篇
神经病学   118篇
特种医学   191篇
外科学   149篇
综合类   33篇
预防医学   122篇
眼科学   14篇
药学   68篇
  1篇
中国医学   9篇
肿瘤学   78篇
  2023年   8篇
  2021年   17篇
  2020年   9篇
  2019年   15篇
  2018年   25篇
  2017年   29篇
  2016年   33篇
  2015年   39篇
  2014年   46篇
  2013年   65篇
  2012年   44篇
  2011年   60篇
  2010年   50篇
  2009年   75篇
  2008年   70篇
  2007年   70篇
  2006年   48篇
  2005年   59篇
  2004年   36篇
  2003年   40篇
  2002年   48篇
  2001年   55篇
  2000年   60篇
  1999年   55篇
  1998年   82篇
  1997年   97篇
  1996年   67篇
  1995年   58篇
  1994年   45篇
  1993年   48篇
  1992年   29篇
  1991年   21篇
  1990年   30篇
  1989年   43篇
  1988年   40篇
  1987年   39篇
  1986年   25篇
  1985年   33篇
  1984年   22篇
  1983年   19篇
  1982年   12篇
  1981年   13篇
  1980年   12篇
  1979年   9篇
  1978年   10篇
  1977年   15篇
  1976年   15篇
  1975年   8篇
  1971年   7篇
  1968年   8篇
排序方式: 共有1907条查询结果,搜索用时 15 毫秒
101.
The authors have performed cochlear implantation since 1985. Different implantation techniques have been used: extracochlear, round window and intracochlear implantation combined with different receivers. Right at the beginning, the 8-channel extra-cochlear implant produces good results due to the gradually increasing current needed to obtain the same effectivity (transduction energy). However, no great differences can be observed in speech reception whether round window or intracochlear implants be used. In addition to audiological results, we briefly outline surgical implantation techniques and implant fixation methods and summarize the outlook for long-term cochlear implantation. Six months after operation, contralateral hearing was observed. The hearing presented itself at one or two frequences.  相似文献   
102.
There is now convincing evidence that the severity of neonatal respiratory distress syndrome can be reduced by surfactant replacement therapy; however, the optimal therapeutic regimen has not been defined. This randomized European multicenter trial was designed to determine whether the beneficial effects of a single large dose of Curosurf (200 mg/kg) in babies with severe respiratory distress syndrome (arterial to alveolar oxygen tension ratio approximately 0.10) could be enhanced by using multiple doses of surfactant. Preterm neonates (birth weight 700 to 2000 g) with severe respiratory distress syndrome requiring artificial ventilation with fraction of inspired oxygen greater than or equal to 0.6 were randomized into two groups at an age of 2 to 15 hours. Both groups received the usual dose of Curosurf (200 mg/kg) immediately after randomization. In neonates randomized to receive multiple-dose treatment, two additional doses of Curosurf (100 mg/kg each) were instilled into the airways (12 and 24 hours after the initial dose) provided that the patients still needed artificial ventilation with fraction of inspired oxygen greater than 0.21. In both groups (single dose: n = 176, multiple doses: n = 167) there was a rapid improvement in oxygenation as reflected by a threefold increase in arterial to alveolar oxygen tension ratio within 5 minutes after surfactant instillation (P less than .001), and peak inspiratory pressure and mean airway pressure could be reduced significantly during the first 6 hours after surfactant treatment. In addition, ventilatory requirement (peak inspiratory pressure, ventilatory efficiency index) was reduced in the multiple-dose group 2 to 4 days after randomization (P less than .05 to .01).(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
103.
In a double blind study, 40 infants with cows' milk intolerance of various causes were randomised to receive a nutritionally complete formula in which nitrogen was supplied either as whey hydrolysate or amino acids. The median age of infants was 10 weeks (range 36 weeks' gestation to 108 weeks' postnatal age). After a median follow up period of 25 weeks there was no significant difference in dietary intake between the formulas. Twenty four weeks after entry, weight and weight for length improved equally on both formulas. Plasma albumin improved significantly on the hydrolysed whey formula but not in the amino acid group. Both milks were palatable and normal intakes of formula were maintained. Biochemical and haematological indices remained within normal limits. There was no difference in stool frequency and vomiting between the two formulas. Two infants developed a probable allergic colitis while receiving hydrolysed whey. Amino acid formula may have a role in the management of atopic infants with severe cows' milk intolerance who have already reacted to whey or casein hydrolysate formula.  相似文献   
104.
The Significance of Mild Squamous Atypia on Cytology   总被引:2,自引:0,他引:2  
Summary: Between January, 1991 and February, 1993 inclusive, 396 Papanicolaou smears were reported to show Mild Squamous Atypia with or without Human Papilloma Virus (MSA ± HPV). All women with MSA ± HPV smears were routinely recalled for colposcopy. To determine the significance of MSA ± HPV on routine smear screening, the records of all patients were reviewed.
Three hundred and thirty-seven women (85.1%) attended the colposcopy clinic and are the subjects analyzed for this report. The remaining 59 (14.9%) failed to attend. Intraepithelial neoplasia was found in 61 patients (18.1%), of whom 27 (8.0%) had a high grade lesion (CIN 2 or 3 or GIN 2). No patient had invasive cancer of the cervix. Only 1 of the 45 pregnant women had a significant lesion.
It is concluded that all asymptomatic women with MSA ± HPV on cervical smear may be managed in accordance with the current NH and MRC recommendations (1) and have a repeat smear in 6 months and colposcopy if the abnormality persists at 12 months.  相似文献   
105.
Polymorphonuclear leukocyte function in term and preterm newborn infants   总被引:1,自引:0,他引:1  
Bacterial infections are a major problem in the care for newborn infants. In search for immunological deficits we investigated phagocytosis and killing of staphylococci using polymorphonuclear leukocytes (PMN) isolated from 2 ml of venous blood. Phagocytosis of PMN from preterm (n = 10) and newborn infants (n = 9; mean birth weights 1,949 and 3,523 g, respectively) was not different from that of adult PMN (n = 14). Killing capacity of PMN from preterm infants was markedly impaired compared to term newborn infants and to adult PMN. We found similar rates of superoxide anion production and similar times for activation in response to phorbolmyristate acetate stimulation. Our study gives further evidence that PMN from term newborn infants have normal phagocytotic and bactericidal capacity. In PMN from preterm newborn infants, however, the bactericidal capacity is diminished similar to newborn infants under stress as described earlier by others.  相似文献   
106.
Since the isolation of a recombinant containing a cDNA sequence for human phenylalanine hydroxylase (hPH) (Woo et al., 1983; Speer et al., 1986) prenatal diagnosis by linked restriction fragment length polymorphism (RFLPs) has become possible for families in which phenylketonuria (PKU) occurs (Lidsky et al., 1985a). We describe here the application of a Hind III three-allele RFLP in a single family, which allowed the prenatal diagnosis of an affected fetus.  相似文献   
107.
Monocytes play an essential role in cellular host defense as circulating phagocytes, as well as precursors of macrophages. We investigated the principal phagocytic activities in monocytes from cord blood of term infants by analysing adherence, random migration, chemotaxis, bactericidal activity, phagocytosis-associated chemiluminescence, production of superoxide anion (O 2 ) and generation of hydrogen peroxide (H2O2). All phagocytic functions of monocytes from neonates were shown quantitatively to be comparable to those of cells from healthy adult volunteers. The increased susceptibility of the human neonate to serious systemic infections cannot be related to an abnormality in monocyte function.Abbreviations FMLP formyl-methionyl-leucyl-phenylalanin - PMA phorbol myristate acetate - CL chemiluminescence - O2 superoxide anion - H2O2 hydrogen peroxide - CGD chronic granulomatous disease - HBSS Hank's balanced salt solution - HSA human serum albumin - SOD superoxide dismutase - KRP-D Krebs Ringer phosphate buffer with dextrose  相似文献   
108.
In 26 infants and children with septicemia or bacterial meningitis, significantly elevated plasma levels of elastase-alpha 1-proteinase inhibitor (E-alpha 1-PI) were present at time of recognition of infection, even in those patients with neutropenia (range of reference values: 25 to 190 micrograms/L, n = 142; patients: 444 to 2049 micrograms/L, n = 26). After initiation of therapy, normalization of E-alpha 1-PI levels was observed in all patients who recovered from infection. In addition, 18 of 19 children with bacterial meningitis had increased cerebrospinal fluid concentrations of E-alpha 1-PI above the range of normal (range of reference values: 0 to 39 micrograms/L, n = 62; patients: 30 to 3490 micrograms/L, n = 19); concentrations of E-alpha 1-PI in bacterial meningitis were significantly increased when compared with those in aseptic meningitis (range 25 to 194 micrograms/L; n = 15). In 30 patients with local bacterial infections (pneumonia, urinary tract infections, etc.), E-alpha 1-PI was also elevated. These data suggest that E-alpha 1-PI is a sensitive indicator of systemic and local bacterial infection in childhood.  相似文献   
109.
As part of an on-going genomic screen of unlinked Charcot-Marie-Tooth disease type 2 (CMT2) families, we identified 11 regions in the genome with lod scores ≥1.0. One of these regions was near the recently identified CMTDI1 locus on 19q. We show evidence of linkage of DUK 1118 to this region and our data reduce the minimum candidate interval for CMTDI1 to the 9-cM interval spanned by D19S586 and D19S432.We also demonstrate that five additional CMT2 families are unlinked to 19q markers, providing further evidence of CMT2 heterogeneity. Electronic Publication  相似文献   
110.

Background  

Congestive heart failure (CHF) has a substantial impact on care utilisation and quality of life. It is crucial for patients to cope with CHF adequately, if they are to live an acceptable life. Self-management may play an important role in this regard. Previous studies have shown the effectiveness of the 'Chronic Disease Self-Management Program' (CDSMP), a group-based cognitive behavioural programme for patients with various chronic conditions. However, the programme's effectiveness has not yet been studied specifically among CHF patients. This paper presents the design of a randomised controlled trial to evaluate the effects of the CDSMP on psychosocial attributes, health behaviour, quality of life, and health care utilisation of CHF patients.  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