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   1489篇
  免费   84篇
  国内免费   9篇
耳鼻咽喉   7篇
儿科学   57篇
妇产科学   113篇
基础医学   224篇
口腔科学   19篇
临床医学   126篇
内科学   373篇
皮肤病学   41篇
神经病学   121篇
特种医学   65篇
外科学   118篇
综合类   13篇
预防医学   69篇
眼科学   32篇
药学   127篇
中国医学   9篇
肿瘤学   68篇
  2023年   12篇
  2022年   28篇
  2021年   40篇
  2020年   23篇
  2019年   34篇
  2018年   45篇
  2017年   40篇
  2016年   43篇
  2015年   38篇
  2014年   57篇
  2013年   99篇
  2012年   101篇
  2011年   120篇
  2010年   68篇
  2009年   44篇
  2008年   59篇
  2007年   76篇
  2006年   64篇
  2005年   73篇
  2004年   66篇
  2003年   45篇
  2002年   51篇
  2001年   33篇
  2000年   41篇
  1999年   24篇
  1998年   15篇
  1997年   10篇
  1996年   7篇
  1995年   8篇
  1994年   7篇
  1993年   14篇
  1992年   14篇
  1991年   14篇
  1990年   17篇
  1989年   12篇
  1988年   13篇
  1987年   18篇
  1986年   12篇
  1985年   12篇
  1984年   7篇
  1983年   15篇
  1982年   7篇
  1981年   5篇
  1980年   3篇
  1975年   7篇
  1972年   3篇
  1971年   4篇
  1970年   5篇
  1967年   4篇
  1875年   2篇
排序方式: 共有1582条查询结果,搜索用时 15 毫秒
81.
Background. Vitiligo is an acquired idiopathic and polygenic disorder with progressive depigmentation of circumscribed patches. Its exact pathogenesis is unknown. The CD4 gene plays an important role in the cell‐mediated immune response and its association with type 1 diabetes mellitus, which is an autoimmune disease, has been previously reported. Methods. Based on the assumption that autoimmunity is also involved in vitiligo, the CD4 gene was selected for study using a candidate gene approach. The pyrimidine‐rich pentanucleotide repeat length polymorphism located in the promoter of the gene was studied. We screened 144 unrelated Iranian patients with vitiligo and 144 healthy matched controls by PCR. Results. The CD4*A4 allele has a susceptibility association with the development of vitiligo in the Iranian population (OR = 1.68, 95% CI 1.18–2.42; P < 0.01, Pc = 0.02). When we compared CD4*A4‐containing genotypes in the case and control groups, even more significant positive association was identified (OR = 2.02, 95% CI 1.26–3.22; P < 0.01 and Pc < 0.01). The CD4 gene polymorphism has a modest association with the development of vitiligo in Iranian patients.  相似文献   
82.
Chronic wounds are important because of their frequency, their chronicity and high costs of treatment. However, there are few primary data on the cost‐of‐illness in Germany. The aim was to determine the cost‐of‐illness of venous leg ulcers (VLU) in Germany. Prospective cost‐of‐illness study was performed in 23 specialised wound centres throughout Germany. Direct, medical, non medical and indirect costs to the patient, statutory health insurers and society were documented. Thereover, health‐related quality of life (QoL) was recorded as intangible costs using the Freiburg quality of life assessment for wounds (FLQA‐w, Augustin). A total of 218 patients (62.1% female) were recruited consecutively. Mean age was 69.8 ± 12.0 years. The mean total cost of the ulcer per year and patient was € 9569, [ € 8658.10 (92%) direct and € 911.20 (8%) indirect costs]. Of the direct costs, € 7630.70 was accounted for by the statutory health insurance and € 1027.40 by the patient. Major cost factors were inpatient costs, outpatient care and non drug treatments. QoL was strikingly reduced in most patients. In Germany, VLU are associated with high direct and indirect costs. As a consequence, there is a need for early and qualified disease management. Deeper‐going cost‐of‐illness‐studies and cost‐benefit analyses are necessary if management of chronic wounds is to be improved.  相似文献   
83.
We screened 217 patients from Germany (n = 213), Austria (n = 2) and Switzerland (n = 2) with a positive family history for amyotrophic lateral sclerosis (ALS) for mutations in the copper/zinc superoxide dismutase (SOD1) gene. We found that 13% of the families tested carried mutations. By analyzing inheritance, we detected a clear-cut co-segregation in 5 of the 28 families; however, in two families with an established mutation, co-segregation was absent. In Germany, the R115G mutation is comparatively frequent and exhibits a specific aggressive phenotype. The L144F mutation, which is the most prevalent mutation in the Balkan countries, and the D90A mutation which is the most frequent SOD1 mutation globally, seem to be the second most common disease-causing mutations in Germany.  相似文献   
84.
85.
Role of IL-12 and IFN-gamma in Pseudomonas aeruginosa corneal infection   总被引:2,自引:0,他引:2  
PURPOSE: In Pseudomonas aeruginosa ocular infection, T-helper cell 1-responsive mouse strains are susceptible (the cornea perforates), and neutralization of IFN-gamma before infection has been shown to delay the onset of perforation. IFN-gamma is the predominant cytokine induced by IL-12, and positive regulation of IL-12 by IFN-gamma, if unchecked, leads to excessive cytokine production and toxicity. Despite its potential importance, the role of IL-12 in ocular infection with P. aeruginosa remains unexplored and was the purpose of this study. METHODS: IL-12 knockout mice, histopathology, RT/PCR and ELISA analyses, immunocytochemistry, and quantitation of viable bacteria in cornea were used to examine the role of IL-12 in IFN-gamma production and the susceptibility phenotype. RESULTS: To directly test the effect of IL-12 on IFN-gamma production, IL-12 knockout and wild-type C57BL/6 mice were used. Both groups of mice were susceptible to infection, with corneal perforation seen at 5 to 7 days after infection. RT-PCR and ELISA analyses confirmed that IL-12 message and protein levels were elevated after infection only in the wild-type mouse cornea. Other differences between the two groups were detected. Knockout versus wild-type mice showed a significant decrease in IFN-gamma mRNA levels in the cornea and cervical lymph nodes and decreased TNF-alpha protein levels in cornea. Corneas of knockout mice also had a significant increase in bacterial load at 5 days after infection when compared with wild-type mice. CONCLUSIONS: These data provide evidence that IL-12 is important in IFN-gamma production and in the absence of the cytokine, both IFN-gamma and TNF-alpha levels in cornea are significantly decreased, resulting in unchecked bacterial growth and perforation.  相似文献   
86.
PURPOSE: To study the possible involvement of the rod (SLC24A1) and cone (SLC24A2) Na-Ca+K exchanger (NCKX) genes in retinal diseases. METHODS: DNA was collected from unrelated patients with retinal disease, mainly from North America. A human genomic library was screened with the cone NCKX cDNA, and hybridizing clones were sequenced to determine the genomic organization of the SLC24A2 gene. The single-strand conformation polymorphism (SSCP) technique and direct sequencing were used to screen the patients' DNA for mutations in SLC24A1 and SLC24A2. The effect of selected missense changes on protein function was tested by measuring potassium-dependent Na-Ca exchange of the mutant proteins expressed in insect cells. RESULTS: Twenty-seven novel sequence changes were found in the rod NCKX gene, 21 of which are unlikely to be pathogenic, because they did not cosegregate with the disease or did not affect conserved regions of the protein. Of the remaining six, two were frameshift mutations found in one patient each. If translated, these alleles would encode nonfunctional proteins. Three of the six possibly pathogenic mutations were missense changes located in conserved regions, and their protein functions were assayed. Only one (Ile992Thr) had a significantly low level of exchanger function, but it was found in two unrelated patients who were heterozygotes with different retinal diseases, and this mutation could not be unequivocally associated with either disease. The last of the six changes is likely to create a new splice acceptor site. The genomic organization of the cone NCKX gene was determined, and it contained 11 exons with a few splice variants. Fifteen novel sequence changes were identified in the cone exchanger gene in patients with a cone dysfunction or degeneration. Only three of these sequence changes, all missense changes found in heterozygous patients, were considered possibly pathogenic. Functional analysis showed only a slight reduction in the activity of the corresponding mutant proteins. CONCLUSIONS: Although variant alleles of the rod and cone NCKX genes were found, none could be definitively associated with a specific retinal disease. The human phenotype associated with mutant exchanger alleles remains unknown.  相似文献   
87.
The collective studies compare in vitro drug release, in vivo skin stripping, and skin blanching response methods for dose responsiveness and bioequivalence assessment of triamcinolone acetonide cream products, as a function of application duration, drug concentration, and manufacturer source. Commercially available triamcinolone acetonide creams (0.025%, 0.1%, and 0.5%) from two manufacturers were evaluated in vitro for rate and extent of drug release across synthetic membranes and in vivo for rate, extent, and variability of drug uptake into human stratum corneum and skin blanching response in human forearm skin. Data demonstrate that increasing triamcinolone acetonide cream concentration applied increased the rate and extent of drug released in vitro as well as the extent of drug uptake and skin blanching response in human skin in vivo. No difference (p < 0.05) between the two sources of 0.1% or 0.5% creams was measured by the skin stripping or skin blanching response methods. Dermatopharmacokinetic analysis of triamcinonide acetonide in vivo is therefore dose responsive to drug concentration applied and application duration and agrees with in vivo skin blanching results. Data support the use of dermatopharmacokinetic methods for bioequivalence and bioavailability assessment of topical drug products.  相似文献   
88.
89.
There is much controversy about the relationship between serum CA-125 levels during in vitro fertilization (IVF) cycles and ovarian function. To evaluate the prognostic value of serum CA-125 and inhibin B measurements in predicting ovarian response to gonadotropin stimulation, we compared the CA-125 and inhibin B levels of poor and normal responders on the first day of ovarian stimulation, on the day of ovulation induction (OI) and at oocyte pick-up. Sixteen patients with poor ovarian response (3 oocytes, serum estradiol (E2) 900 pg/ml at OI) in IVF/intracytoplasmic sperm injection cycles were matched with normal responders (6 oocytes, E2 1800 pg/ml) by age, spontaneous cycle day-3 follicle-stimulating hormone level and cause of infertility. Inhibin B concentrations were significantly lower at all three time points in poor responders, but CA-125 levels were not. No statistically significant correlation was found between CA-125 levels and any of the clinical or laboratory parameters examined. Thus, CA-125 measurements during stimulation are not useful in predicting or identifying poor ovarian response to gonadotropin stimulation in IVF cycles. The lack of difference in CA-125 concentrations between poor and normal responders and lack of correlation with E2 or inhibin B levels suggest that ovarian steroidogenesis and other granulosa cell functions do not influence the production of CA-125. Inhibin B, however, seems to predict ovarian response as early as at the start of stimulation.  相似文献   
90.
BACKGROUND: Among other causes of virilization, ovarian tumors can be the cause of excessive androgen production. We report the case of a Leydig cell tumor of the ovary where diagnostic attempts to localize the source of hyperandrogenism preoperatively failed owing to relatively small tumor size. CASE: A 36-year-old woman presented with clinical signs of severe virilization including progressive balding, increased hirsutism, secondary amenorrhea and enlargement of the clitoris. Extensive work-up included endocrinological tests, pelvic ultrasound, magnetic resonance imaging, chromosomal analysis, norcholesterol scintigraphy and selective venous sampling, without direct localization of the source of hyperandrogenism. Persistently high plasma testosterone prompted an explorative laparotomy. Intraoperative selective blood sampling of the ovarian veins and palpation gave evidence of a right ovarian tumor, which was then removed. Histological examination revealed the presence of a pure Leydig cell tumor. CONCLUSION: Exploratory laparotomy with intraoperative selective blood sampling of the ovarian veins might be a useful approach in patients without accurate preoperative localization of androgen-producing tumors of the ovaries.  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