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   2350篇
  免费   158篇
  国内免费   21篇
耳鼻咽喉   20篇
儿科学   121篇
妇产科学   26篇
基础医学   258篇
口腔科学   85篇
临床医学   198篇
内科学   440篇
皮肤病学   52篇
神经病学   145篇
特种医学   194篇
外国民族医学   1篇
外科学   317篇
综合类   76篇
一般理论   2篇
预防医学   177篇
眼科学   113篇
药学   202篇
中国医学   13篇
肿瘤学   89篇
  2023年   24篇
  2022年   42篇
  2021年   81篇
  2020年   45篇
  2019年   47篇
  2018年   70篇
  2017年   57篇
  2016年   57篇
  2015年   71篇
  2014年   88篇
  2013年   108篇
  2012年   139篇
  2011年   141篇
  2010年   96篇
  2009年   96篇
  2008年   128篇
  2007年   81篇
  2006年   84篇
  2005年   78篇
  2004年   80篇
  2003年   67篇
  2002年   45篇
  2001年   29篇
  2000年   33篇
  1999年   39篇
  1998年   62篇
  1997年   69篇
  1996年   62篇
  1995年   50篇
  1994年   44篇
  1993年   41篇
  1992年   21篇
  1991年   26篇
  1990年   28篇
  1989年   25篇
  1988年   41篇
  1987年   36篇
  1986年   31篇
  1985年   19篇
  1984年   14篇
  1983年   11篇
  1982年   19篇
  1980年   11篇
  1979年   10篇
  1978年   9篇
  1977年   8篇
  1976年   8篇
  1974年   7篇
  1973年   5篇
  1972年   5篇
排序方式: 共有2529条查询结果,搜索用时 15 毫秒
11.
Localization of a gene for otosclerosis to chromosome 15q25-q26   总被引:5,自引:0,他引:5  
Among white adults otosclerosis is the single most common cause of hearing impairment. Although the genetics of this disease are controversial, the majority of studies indicate autosomal dominant inheritance with reduced penetrance. We studied a large multi- generational family in which otosclerosis has been inherited in an autosomal dominant pattern. Five of16 affected persons have surgically confirmed otosclerosis; the remaining nine have a conductive hearing loss but have not undergone corrective surgery. To locate the disease- causing gene we completed genetic linkage analysis using short tandem repeat polymorphisms (STRPs) distributed over the entire genome. Multipoint linkage analysis showed that only one genomic region, on chromosome 15q, generated a lod score >2.0. Additional STRPs were typed in this area, resulting in a lod score of 3.4. STRPs FES (centromeric) and D15S657 (telomeric) flank the 14. 5 cM region that contains an otosclerosis gene.   相似文献   
12.
OBJECTIVE: Oxidative stress such as free radical-mediated neuronal dysfunction may be involved in the pathophysiology of schizophrenia. The human glutathione peroxidase (GPX1) is a selenium-dependent enzyme, which plays an important role in the detoxification of free radicals. We therefore hypothesized that the GPX1 gene, which is located on chromosome 3p21.3, may be involved in the pathophysiology of schizophrenia. The aim of this study is to examine whether a potentially functional polymorphism, a proline (Pro) to leucine (Leu) substitution at codon 197 (Pro197Leu) of the human GPX1 gene, is associated with susceptibility to schizophrenia. METHODS: We genotyped the Pro197Leu polymorphism in a total of 113 nuclear families that had a proband with schizophrenia. Genetic association was tested using the transmission disequilibrium test (TDT), the sib transmission disequilibrium test (STDT), and the family-based association test (FBAT). RESULTS: The minor allele (Leu) frequency was calculated to be 0.282. We could not find significant transmission disequilibrium of the alleles for the Pro197Leu polymorphism in the GPX1 gene in association with the presence of schizophrenia in our family sample (TDT, chi2=0.03, degrees of freedom=1, P=0.86; combined TDT-STDT, Z'=-0.052, P=0.47; FBAT, Z=0.000, P=1.000). CONCLUSION: The results of this study suggest that the GPX1 polymorphism is unlikely to be associated with susceptibility to schizophrenia.  相似文献   
13.
There is increasing evidence that immunological mechanisms play a role in the pathogenesis and pathophysiology of endometriosis. It was therefore of interest to study interleukin-8 (IL-8), a chemokine, in the peritoneal fluid and peripheral blood of women undergoing laparoscopic procedures. The presence and concentrations of IL-8 in relation to endometriosis, infertility and abdominal pain were evaluated. Samples of peritoneal fluid (n = 49) and peripheral blood (n = 50) were obtained from 50 consecutive patients undergoing laparoscopic surgery for various gynaecological indications (abdominal pain, infertility, sterilization). IL-8 was present in the peritoneal fluid of most women (87%). The concentration of IL-8 in the peritoneal fluid was higher in women with endometriosis compared to women without (P = 0.02). This difference was more pronounced in early (stage 1) endometriosis (P = 0.001). IL-8 concentrations in the peritoneal fluid were also higher in women with early endometriosis compared to women with later stages of the disease (P = 0.003). Peripheral blood concentrations did not correlate with peritoneal fluid concentrations of IL-8 and/or the presence of endometriosis. We conclude that IL-8 is an important factor that may contribute to the pathogenesis of endometriosis possibly by promoting neovascularization. This information can be a guide in the development of new therapeutic approaches for the treatment of endometriosis.   相似文献   
14.
Twenty isolates of Salmonella typhi from cases of typhoid during the 1989-1990 epidemic in Calcutta were examined. Most isolates (84% of all isolates in the epidemic) were resistant to chloramphenicol, ampicillin, tetracycline and streptomycin but were sensitive to nalidixic acid and ciprofloxacin. Plasmids of 120 kb and 14 kb were identified amongst the multi-drug resistant isolates of S. typhi. However, there was no plasmid in the antibiotic-sensitive isolates. The 120-kb plasmid was transferable and transconjugants were resistant to chloramphenicol, ampicillin, tetracycline and streptomycin. Restriction endonuclease analysis patterns after EcoRI digestion of the 120-kb antibiotic-resistance plasmids from the S. typhi isolates and transconjugants were similar.  相似文献   
15.
R Shaikh  M Linial  S Brown  A Sen  R Eisenman 《Virology》1979,92(2):463-481
The internal structural (gag) proteins of recombinant avian oncoviruses selected for the env gene of RAV-O (an endogenous chicken virus) and the src gene for PR-RSV-C were examined. Eight of ten clones of such recombinants were found to synthesize altered gag proteins. The gag proteins of one recombinant clone, PR-E-95c, were examined in more detail by gel electrophoresis and tryptic peptide mapping. These methods have allowed us to distinguish between the gag proteins of the two parental viruses and to determine from which virus the proteins of the recombinant virus were derived. PR-E-95c virions were found to contain p270, an electrophoretically distinguishable variant of p27 which is found in isolates of RAV-0. This recombinant virus also contains p12/15, which is electrophoretically indistinguishable from the p12/15 of both of the parental viruses. However, tryptic peptide analysis of p15 indicates that PR-E-95c has inherited PR-RSV-C-specific p15 sequences. These observations suggest that at least one cross-over has occurred between p15 and p27 in PR-E-95c. A striking difference between the proteins of PR-E-95c virus and those of the parental viruses is that the recombinant lacks polypeptides migrating in the position of p19 and contains two novel polypeptides termed p19α (MW 20,000) and p19β (MW 15,000). Both of these polypeptides are phosphorylated and share antigenic determinants and some tryptic peptides with parental p19. As determined by peptide analysis and radioimmunoassay, these p19-related proteins contain information from both parental viruses, suggesting that PR-E-95c has another cross-over within p19. The altered p19 proteins bind to viral RNA specifically and are associated with genomic RNA in the virion. Neither the stability nor the specific infectivity of the recombinant viruses appears to be significantly affected by the altered proteins.  相似文献   
16.
17.
Summary A cortico-cancellous flap from the anterolateral aspect of the upper third of the tibia was presented. Sixty lower limbs of fresh cadavers were dissected. The vascular bundle includes the anterior tibial artery and its recurrent collateral branches and recurrent and muscllo periostal arteries. The flap is harvested with the interosseous membrane and can be used either free or pedicled. We used this flap for two patients suffering from pseudarthrosis. Long range clinical and radiological results are good.
Le transfert osseux vascularisé tibial superieur
Résumé Les auteurs décrivent un transfert ostéo-periosté vascularisé, prélevé sur la face antéro-latérale de l'extremité supérieure du tibia. L'étude anatomique porte sur soixante membres inférieurs, conservés au froid. La vascularisation métaphysaire du transfert provient de la branche récurrente tibiale antérieure et de ses rameaux, la vascularisation diaphysaire étant issue des branches musculo-périostiées proximales. Le transfert vascularisé est prélevé avec la membrane interosseuse et peut être pediculé ou libre. L'expérience clinique porte sur deux cas de pseudarthroses multiopérées. Les résultats cliniques et radiologiques sont bons à long terme.
  相似文献   
18.
Rapid enterovirus detection is important for decisions about antibiotic administration and length of hospital stay. The efficacy of rapid antigen detection-cell culture amplification (Ag-CCA) was evaluated with monoclonal antibodies (MAbs) 5-D8/1 (DAKO) and Pan-Enterovirus clone 2E11 (Chemicon) with 10 poliovirus, echovirus, and coxsackievirus type A and B stock isolates and College of American Pathologists check samples. By using Ag-CCA technology, MAb 2E11 was more sensitive than 5-D8/1 at detecting a greater number of stock isolates at or past tube (cytopathic effect [CPE]) culture (TC) end points. The efficacy of Ag-CCA in the clinical setting was subsequently confirmed with 273 consecutively freshly collected nasopharyngeal aspirate or swab specimens, rectal swab, and cerebrospinal fluid specimens during the 1999 enterovirus season. All specimens were tested by Ag-CCA in parallel with rhesus monkey kidney (RhMk), MRC-5, and A549 conventional TCs. Approximately 60% of field specimens were additionally tested with Hep-2 and HNK conventional TCs. Sixty-two percent of the clinical specimens tested were Ag-CCA positive after 48 h. Among 51 isolates, the mean time to CPE or culture confirmation was 5.5 days (range, 2 to 18 days). After 48 h, Ag-CCA achieved sensitivity, specificity, and positive and negative predictive values of 62, 100, 100, and 93%, respectively. During the same period, TC-CPE displayed test parameters of 12, 100, 100, and 85%, respectively. After 5 days, the sensitivity and specificity of Ag-CCA increased to 92 and 98%, respectively. Within the same period, isolation attained sensitivity and specificity of 52 and 100%, respectively. Although Ag-CCA displayed slightly reduced sensitivity and reduced specificity compared with conventional cell culture after 14 days, the markedly superior 48-h enterovirus Ag-CCA detection rate supports incorporation of this assay into the routine clinical setting.  相似文献   
19.
Fifty women with polycystic ovaries took part in a prospective randomized study. All women required treatment by in-vitro fertilization (IVF) for reasons other than anovulation. They had all previously undergone ovarian stimulation with gonadotrophin therapy which had failed to result in pregnancy or had been abandoned due to high risk of developing ovarian hyperstimulation syndrome (OHSS). Twenty-five women were treated by long-term pituitary desensitization followed by gonadotrophin therapy, oocyte retrieval and embryo transfer (group 1). Twenty-five women underwent laparoscopic ovarian electrocautery after pituitary desensitization followed by gonadotrophin therapy, oocyte retrieval and embryo transfer (group 2). A significantly higher number of women in group 1 had to have the treatment cycle abandoned due to impending or actual OHSS, determined by endocrine and clinical findings. In addition, the development of moderate or severe OHSS in completed cycles was higher in group 1. The pregnancy rate and miscarriage rates in the two treatment groups were similar. The authors propose that laparoscopic ovarian electrocautery is a potentially useful treatment for women who have previously had an IVF treatment cycle cancelled due to risk of OHSS or who have suffered OHSS in a previous treatment cycle.   相似文献   
20.

Background  

The purpose of the present investigation was to determine if the salivary counts of 40 common oral bacteria in subjects with an oral squamous cell carcinoma (OSCC) lesion would differ from those found in cancer-free (OSCC-free) controls.  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