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   7047篇
  免费   300篇
  国内免费   24篇
耳鼻咽喉   70篇
儿科学   270篇
妇产科学   442篇
基础医学   1212篇
口腔科学   148篇
临床医学   515篇
内科学   1196篇
皮肤病学   376篇
神经病学   549篇
特种医学   302篇
外科学   904篇
综合类   63篇
一般理论   4篇
预防医学   265篇
眼科学   178篇
药学   362篇
肿瘤学   515篇
  2022年   47篇
  2021年   99篇
  2020年   62篇
  2019年   87篇
  2018年   88篇
  2017年   74篇
  2016年   91篇
  2015年   101篇
  2014年   145篇
  2013年   209篇
  2012年   274篇
  2011年   317篇
  2010年   204篇
  2009年   193篇
  2008年   299篇
  2007年   297篇
  2006年   328篇
  2005年   335篇
  2004年   346篇
  2003年   306篇
  2002年   307篇
  2001年   159篇
  2000年   156篇
  1999年   146篇
  1998年   84篇
  1997年   52篇
  1996年   45篇
  1995年   48篇
  1994年   40篇
  1993年   43篇
  1992年   65篇
  1991年   70篇
  1990年   58篇
  1989年   57篇
  1988年   68篇
  1987年   71篇
  1986年   57篇
  1985年   71篇
  1984年   53篇
  1983年   34篇
  1979年   55篇
  1975年   39篇
  1971年   31篇
  1969年   32篇
  1932年   31篇
  1931年   35篇
  1930年   35篇
  1928年   43篇
  1913年   43篇
  1912年   30篇
排序方式: 共有7371条查询结果,搜索用时 11 毫秒
81.
82.
OBJECTIVE: We determined whether contrast-enhanced color Doppler sonography can differentiate benign from malignant enlarged cervical lymph nodes in head and neck tumors. SUBJECTS AND METHODS: Ninety-four enlarged lymph nodes in 39 adult patients (32 men and seven women; age range, 30-81 years) were examined with B-mode sonography and with unenhanced and contrast-enhanced color Doppler sonography. All patients had carcinoma of the oral cavity. Histologically, lymphadenitis was found in 57 nodes and metastases in 37 nodes. Geometric dimension, texture, and margin of the node and detection and location of vessels were noted. Histology and imaging findings were correlated. RESULTS: The transverse-to-longitudinal diameter ratio in combination with texture and margin analysis resulted in a correct diagnosis in only approximately 79% of the nodes. With contrast-enhanced color Doppler sonography, 86% of nodes showed vessels, and 28% of nodes showed vessels with this technique exclusively. Characteristic configurations were identified: hilar vessels with branching indicated lymphadenitis (sensitivity, 98%; specificity, 100%), and predominantly peripheral vessels indicated metastases (100%, 98%). These findings changed the diagnosis in 13 nodes, changed the therapy in four patients, and led to an incorrect diagnosis in one patient. CONCLUSION: Enlarged lymph nodes can be characterized as metastatic or inflammatory with high diagnostic accuracy on the basis of their vascular architecture as seen on contrast-enhanced color Doppler sonography.  相似文献   
83.
84.
85.
PURPOSE: A phase III study to determine whether a weekly docetaxel schedule improves the therapeutic index compared with the classic 3-weekly schedule. PATIENTS AND METHODS: Patients with stage IIIB-IV non-small-cell lung cancer (NSCLC) were randomly assigned to docetaxel 75 mg/m2 on day 1 every 3 weeks (3-weekly) and 35 mg/m2 on days 1, 8, and 15 (weekly) for < or = eight cycles. End points included survival (primary), toxicity, and response. RESULTS: Of 215 patients enrolled, 208 (103 in the 3-weekly arm and 105 in the weekly arm) were assessable for response. At baseline, 24.5% of patients (51 out of 208) had received prior paclitaxel therapy and 43.3% of patients (90 out of 208) had been progression-free for more than 3 months after first-line therapy. After 12 months' follow-up, median survival was 6.3 months (95% CI, 4.68 to 7.84 months) with 3-weekly docetaxel and 9.2 months (95% CI, 5.83 to 12.59 months) with weekly docetaxel (P = .07) after a median of four (range, one to eight) and two (range, one to eight) treatment cycles, respectively. Overall, response rates were 12.6% v 10.5% with 3-weekly versus weekly docetaxel. Significantly fewer patients reported grade 3 to 4 toxicities with weekly docetaxel versus 3-weekly docetaxel (P < or = .05). There were significantly lower rates of grade 3 to 4 anemia (P < or = .05), leucopenia (P < .0001), and neutropenia (P < or = .001) with weekly versus 3-weekly treatment. No grade 3 to 4 thrombocytopenia or mucositis was reported. CONCLUSION: Weekly docetaxel 35 mg/m2 demonstrated similar efficacy and better tolerability than standard 3-weekly docetaxel 75 mg/m2 and can be recommended as a feasible alternative second-line treatment option for patients with advanced NSCLC.  相似文献   
86.
IntroductionOxidative stress (OS) occurs in cystic fibrosis (CF).ObjectiveThe objective of this work is to evaluate the influence of bacterial infection on biomarkers of OS (catalase [CAT], glutathione peroxidade [GPx], reduced glutathione [GSH]), markers of oxidative damage (protein carbonyls [PC], thiobarbituric acid reactive substances [TBARS]), together with the nutritional status and lung function in children with CF.MethodsCross‐sectional study including CF group (CFG, n = 55) and control group (CG, n = 31), median age: 3.89 and 4.62 years, respectively. CFG was distributed into CFG negative bacteriology (CFGB−, n = 27) or CFG positive bacteriology (CFGB+, n = 28), and CFG negative Pseudomonas aeruginosa (CFGPa−, n = 36) or CFG positive Pseudomonas aeruginosa (CFGPa+, n = 19).ResultsCompared with CG, CFG (P = .034) and CFGB+ (P = .042) had lower body mass index‐for‐age z‐score; forced expiratory volume in the first second was lower in CFGB+ and CFGPa+ (both P < .001). After adjusting for confounders and compared with CG: CFG showed higher TBARS (P ≤ .001) and PC (P = .048), and lower CAT (P = .004) and GPx (P = .003); the increase in PC levels was observed in CFGB+ (P = .011) and CFGPa+ (P = .001) but not in CFGB− (P = .510) and CFGPa− (P = .460).ConclusionsThese results indicate a systemic OS in children with CF. The presence of bacterial infection particularly Pseudomonas aeruginosa seems to be determinant to exacerbate the oxidative damage to proteins, in which PC may be a useful biomarker of OS in CF.  相似文献   
87.
88.
PurposeEvaluation of mRNA and microRNA (miRNA) expression in epithelium and stroma of patients with keratoconus.MethodsThe epithelium and stroma of eight corneas of eight patients with keratoconus and eight corneas of eight non-keratoconus healthy controls were studied separately. RNA was extracted, and mRNA and miRNA analyses were performed using microarrays. Differentially expressed mRNAs and miRNAs in epithelial and stromal keratoconus samples compared to healthy controls were identified. Selected genes and miRNAs were further validated using RT-qPCR.ResultsWe discovered 170 epithelial and 1498 stromal deregulated protein-coding mRNAs in KC samples. In addition, in epithelial samples 180 miRNAs and in stromal samples 379 miRNAs were significantly deregulated more than twofold compared to controls. Pathway analysis revealed enrichment of metabolic and axon guidance pathways for epithelial cells and enrichment of metabolic, mitogen-activated protein kinase (MAPK), and focal adhesion pathways for stromal cells.ConclusionsThis study demonstrates significant differences in the expression and regulation of mRNAs and miRNAs in the epithelium and stroma of Patients with KC. Also, in addition to the well-known target candidates, we were able to identify further genes and miRNAs that may be associated with keratoconus. Signaling pathways influencing metabolic changes and cell contacts are affected in epithelial and stromal cells of patients with keratoconus.  相似文献   
89.
There are only scarce data on the incidence of spontaneous pregnancy in infertility patients. Contraception after infertility treatment is another topic that has been neglected so far. Therefore, a questionnaire was sent to 1614 couples with a child conceived by intracytoplasmic sperm injection (ICSI) aged 4-6 years. A total of 899 couples responded (response rate 55.7%). A total of 10.9% of couples had used contraception. Of the couples that had actively tried to conceive, 20.0% had conceived spontaneously, resulting in a live-birth rate of 16.4%. 74.5% of these pregnancies were conceived within 2 years after delivery. A further 26.6% of couples conceived again by ICSI, with a live-birth rate of 20.9%. Maternal age was the only prognostic factor for spontaneous conception. Parents of multiples after ICSI did not have a higher chance of spontaneous conception than parents of singletons. Couples can be counselled that one out of five couples conceive spontaneously after successful ICSI. Even when assuming that none of the families that were lost to follow-up had conceived spontaneously, one out of eight couples would have conceived spontaneously. Therefore, it is important to counsel patients about the possibility of natural conception and necessity to use contraception despite their history of subfertility.  相似文献   
90.
This paper deals with the question of whether measuring hormones is necessary in eumenorrhoeic infertility patients. The answer presented here is yes, but there are some remaining and debatable problems. In our opinion, eumenorrhoea results from regular folliculogenesis, ovulation and luteal function. To be time- and cost-effective, only a limited number of hormones should be measured and assessment of the luteal phase in an eumenorrhoeic patient by measuring oestradiol and progesterone is questionable. The paper discusses the questions on the basis of the currently available literature.  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