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   595篇
  免费   28篇
  国内免费   21篇
耳鼻咽喉   1篇
儿科学   29篇
妇产科学   18篇
基础医学   46篇
口腔科学   4篇
临床医学   57篇
内科学   76篇
皮肤病学   119篇
神经病学   11篇
特种医学   80篇
外科学   59篇
综合类   44篇
预防医学   36篇
眼科学   4篇
药学   52篇
肿瘤学   8篇
  2016年   3篇
  2014年   5篇
  2013年   5篇
  2010年   4篇
  2009年   8篇
  2008年   5篇
  2007年   12篇
  2001年   3篇
  2000年   4篇
  1999年   4篇
  1998年   15篇
  1997年   12篇
  1996年   19篇
  1995年   22篇
  1994年   21篇
  1993年   19篇
  1992年   8篇
  1991年   17篇
  1990年   12篇
  1989年   22篇
  1988年   21篇
  1987年   30篇
  1986年   21篇
  1985年   18篇
  1984年   15篇
  1983年   13篇
  1982年   13篇
  1981年   12篇
  1980年   9篇
  1979年   4篇
  1978年   4篇
  1977年   8篇
  1976年   14篇
  1975年   4篇
  1974年   4篇
  1973年   5篇
  1972年   3篇
  1970年   6篇
  1967年   3篇
  1966年   3篇
  1963年   6篇
  1962年   2篇
  1959年   18篇
  1958年   29篇
  1957年   34篇
  1956年   28篇
  1955年   24篇
  1954年   30篇
  1949年   7篇
  1948年   6篇
排序方式: 共有644条查询结果,搜索用时 15 毫秒
1.
2.
3.
Sixteen patients with minimal facial acne but with symptoms of dysmorphophobia related to their acne were treated with isotretinoin, 0.5 mg/kg/day, (n = 5); 1 mg/kg/day (n = 11) for 16 weeks. All 16 had previously received long-term antibiotic therapy with no 'perceived' improvement in their acne. Formal psychiatric assessment was not possible through lack of cooperation. Fourteen of 16 patients derived benefit from isotretinoin therapy in that all 14 were subsequently satisfied with the cosmetic results achieved. However, the incidence of relapse was greater than that for a control group, 14 requiring additional therapy in the form of antibiotics or further isotretinoin (seven patients) within 20 months of completing the original course. Patients with acne and dysmorphophobia represent an important group of patients who benefit from treatment with isotretinoin; if possible this should be in conjunction with psychotherapy.  相似文献   
4.
Data were obtained from a random sample of 87 secondary schoolsin Wales (UK) about the organization and provision of healtheducation teaching, the implementation of health related policies,and the involvement of outside agencies and professionals inthe planning and delivery of health education programmes. Theresults suggest that schools have made progress in curriculumdevelopment. However, if the concept of the health promotingschool is to be translated into practice, greater attentionwill need to be given us the development of broadly based policiesfor health covering both pupils and staff and the better integrationof school programmes with community resources. Greater understandingof the health promoting school concept by teaching staff andthe development of examples of good practice in embedding healtheducation into national curriculum subjects, are also advocated.  相似文献   
5.
The human mucosal immune system is structurally mature and has all the necessary cellular components to generate an immune response at birth. However, in the absence of dietary antigens and bacterial flora, there are no secondary follicles in the Peyer's patches and virtually no immunoglobulin A plasma cells in the lamina propria. Reactive follicle centers develop after birth but it takes 2 years for mucosal IgA plasma cell density to reach adult levels. T cells are present in the epithelium and lamina propria at birth, albeit at a lower frequency than later in life and there are major differences in phenotype between T cells in fetal intestine and postnatal intestine. There is no information on the impact of the massive antigenic challenge at birth on the mucosal immune system. Well-documented deficiencies in the ability of the blood T cells of the neonate to produce interleukin-4 and interferon-gamma may also occur in the intestine. It is still an open question whether it is better to try to prevent immunological sensitization of the newborn by avoiding potential allergens (i.e. cow's milk), or whether early exposure (as happens when premature infants are given formula feeds) might tolerize the infant. Hydrolysed cow's milk formulae are probably less antigenic than whole cow's milk and have been widely used in the treatment of cow's milk allergy. Some thought is now being given as to whether the prophylactic use of hydrolysates can reduce cow's milk allergy in ‘at-risk’ infants.  相似文献   
6.
Blood donation behavior of Hispanics in the lower Rio Grande Valley   总被引:2,自引:0,他引:2  
WW Thompson 《Transfusion》1993,33(4):333-335
This study was designed to determine the blood donation behavior and attitudes of Hispanic residents of the Lower Rio Grande Valley for the purpose of developing promotional and educational approaches to enhance levels of donor participation. Personal interviews of 545 respondents were conducted in English and Spanish using quota sampling and standard intercept techniques at lower- and middle-income supermarkets in five cities during a payday weekend. A number of research hypotheses were established to test for demographic, behavioral, and attitudinal differences that were observed in donors and nondonors using chi-square analysis and multiple discriminant analysis. After analyzing the difference between Hispanics and non-Hispanics for blood donation rates, all non-Hispanics were eliminated from analysis, and the remaining 419 Hispanics were evaluated on the basis of their donor behavior. Donation among Hispanics was most likely to be by better- educated, English-speaking, higher-job-status individuals who had participated in a blood donation drive. Donors tend to have parent(s) who were donors, and they were also more likely to carry an organ donor card. Donors were found to vary in their behaviors as well as their attitudes and beliefs. Perceptions of a lack of safety in donating, the risk of contracting acquired immune deficiency syndrome, and the financial motivation of donors were most pronounced among Hispanics, which indicated a need for improved education on these issues.  相似文献   
7.
Mast cells and T lymphocytes in chronic urticaria   总被引:1,自引:0,他引:1  
Mast cells are considered to be the primary effector cells in urticaria but it is possible that lymphocytes contribute to the formation of weals by secreting histamine releasing factors. The aim of this study was to examine the population of mast cells and to quantify the T cell subsets and their activation status in delayed pressure urticaria (DPU), chronic idiopathic urticaria and normal controls. Three biopsies were obtained from each of four patients with chronic idiopathic urticaria but not DPU. Three biopsies were taken from each of 13 patients with DPU, from a combination of unchallenged skin and at 0, 2, 6, 24, 48 and 120 h after weighted steel rods (diameter 1.5 cm) had been applied to the thighs. Three biopsies were similarly obtained from each of four normal controls before an identical pressure challenge and at 6, 24 and 48 h afterwards. The chloracetate esterase stain was used to demonstrate mast cells and an alkaline phosphatase anti-alkaline phosphatase immunohistochemical technique to assess the phenotypic and activation characteristics of the T cell infiltrate. The mast cell count did not differ significantly between unchallenged skin from DPU patients and normal controls. Following a pressure challenge to the DPU patients, the number of stainable mast cells decreased significantly to a level comparable with that in spontaneous weals of chronic idiopathic urticaria. Investigation of T cell subsets showed a preponderance of CD4+ cells over CD8+ cells. There was no evidence of T cell activation in chronic idiopathic urticaria or DPU when compared with normal controls. These data support the view that mast cell degranulation occurs in chronic idiopathic urticaria and suggest that it may also play a role in the pathogenesis of DPU. There was no evidence that lymphocyte activation occurs in either condition.  相似文献   
8.
The role that maternal and fetal human leukocyte antigen (HLA) genes play in pregnancy is unknown, but it has been suggested that fetuses whose HLA alleles do not differ from maternal alleles (i.e. histocompatible fetuses) are more likely to be aborted than fetuses with HLA alleles that differ from maternal alleles (i.e. histoincompatible fetuses). To elucidate the role of HLA compatibility in pregnancy, we tested the hypothesis that couples who match for HLA alleles or haplotypes would have reduced fertility because only these couples could produce histocompatible fetuses. We conducted a 10 year prospective study of HLA matching and pregnancy outcome in 111 Hutterite couples, providing information on 251 pregnancies. A logistic regression analysis was performed to determine the effects of HLA matching at HLA regions and loci on pregnancy outcome (fetal loss versus delivery). Significantly increased fetal loss rates were observed among couples matching for the entire 16-locus haplotype (P = 0.002). Among the individual loci, loss rates were increased among couples matching for HLA-B (P = 0.019), HLA-C (P = 0.033) and the complement component, C4 (P = 0.043). We interpret these results as evidence that matching for the entire 16-locus haplotype and/or alleles at an HLA-B-linked locus confers significant risk for fetal loss.   相似文献   
9.
Marrow regeneration after mechanical depletion   总被引:1,自引:0,他引:1  
Brecher  G; Tjio  JH; Smith  WW; Haley  JE 《Blood》1976,48(5):679-686
The origin of marrow regeneration after mechanical depletion was reinvestigated in mouse chimeras. The results were compatible with the local origin of stem cells from remnants of incompletely removed marrow, but not with their origin from a common precursor of both bone and hemopoietic cell lines. In transplanted femurs depleted by a modified technique of in vivo evacuation of marrow, hemopoietic regeneration failed to occur. The presence of hemopoietic stem cells in the Haversian canals was thus excluded. The demonstration of ample hemopoiesis with minimal bone formation in nondepleted controls in which bone marrow initially became necrotic provided new evidence that osteogenesis was not a prerequisite of hemopoietic regeneration.  相似文献   
10.
The glenohumeral joint is inherently unstable because the large humeral head articulates with the small shadow glenoid fossa. Traumatic anterior dislocation of the shoulder is a relatively common athletic injury, and the high frequency of recurrent instability in young athletes after shoulder dislocation is discouraging to both the patient and the treating physician. Management of primary traumatic shoulder dislocation remains controversial. Traditionally, treatment involves initial immobilisation for 4–6 weeks, followed by functional rehabilitation. However, in view of the high recurrence rates associated with this traditional approach, there has been an escalating interest in determining whether immediate surgical intervention can lower the rate of recurrent shoulder dislocation, improving the patient’s quality of life. This review article aims to provide an overview of the nature and pathogenesis of first-time primary anterior shoulder dislocations, the widely accepted management modalities, and the efficacy of primary surgical intervention in first-time primary anterior shoulder dislocations.  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