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   8123篇
  免费   620篇
  国内免费   42篇
耳鼻咽喉   70篇
儿科学   181篇
妇产科学   145篇
基础医学   1058篇
口腔科学   456篇
临床医学   736篇
内科学   1696篇
皮肤病学   144篇
神经病学   543篇
特种医学   234篇
外国民族医学   5篇
外科学   1159篇
综合类   90篇
一般理论   7篇
预防医学   922篇
眼科学   233篇
药学   485篇
中国医学   22篇
肿瘤学   599篇
  2023年   76篇
  2022年   111篇
  2021年   201篇
  2020年   129篇
  2019年   162篇
  2018年   223篇
  2017年   136篇
  2016年   185篇
  2015年   219篇
  2014年   252篇
  2013年   399篇
  2012年   557篇
  2011年   548篇
  2010年   304篇
  2009年   262篇
  2008年   458篇
  2007年   481篇
  2006年   439篇
  2005年   437篇
  2004年   372篇
  2003年   353篇
  2002年   307篇
  2001年   93篇
  2000年   105篇
  1999年   108篇
  1998年   72篇
  1997年   69篇
  1996年   46篇
  1995年   53篇
  1994年   41篇
  1993年   61篇
  1992年   68篇
  1991年   62篇
  1990年   77篇
  1989年   51篇
  1988年   41篇
  1987年   61篇
  1986年   54篇
  1985年   66篇
  1984年   57篇
  1983年   45篇
  1982年   62篇
  1981年   53篇
  1980年   52篇
  1979年   38篇
  1978年   48篇
  1977年   50篇
  1976年   42篇
  1975年   40篇
  1969年   35篇
排序方式: 共有8785条查询结果,搜索用时 31 毫秒
31.
The outcome of 336 unselected patients diagnosed as having bladder cancer in 1985 in a southern health region of Norway was studied. Two hundred and forty patients had superficial bladder cancer (Tis, Ta and T1). Seventy-four had T2-3 and 17 had T4 bladder tumours at the time of diagnosis (the T-category was unknown in five cases). In 46 of 248 evaluable cases (19%) 12 or more months had elapsed between the onset of symptoms and the histological confirmation of the diagnosis. The information received from the initial routine histology report was inadequate in 51 of 240 (21%) of the patients with superficial bladder cancer. Among the 91 patients with muscle-infiltrating tumours the primary treatment varied considerably, and only 15 patients underwent total cystectomy as the initial treatment. Only 46 in whom muscle-infiltrating tumours were diagnosed initially were referred to the regional uro-oncological unit during the course of the disease. The cancer-corrected, four-year survival was 86% and 42% for superficial and muscle infiltrating bladder cancer, respectively. The comparable figures for crude survival were 64% and 34%, respectively. The lack of optimal standard treatment of muscle-infiltrating bladder cancer warrants the introduction of clinical trials to assess both curative and palliative regimens as well as to study prognostic factors such as proliferation and immunohistochemical parameters by uro-oncological units. Scandinavian Cancer Registries should consider the optional recording of the T category on the case record forms for newly diagnosed cases of bladder cancer.  相似文献   
32.
The use of myocardial perfusion (82)Rb PET/CT studies continues to increase but its accuracy using database quantification methods for the diagnosis of coronary artery disease (CAD) has not been established. METHODS: A sex-independent normal database and criteria for abnormality for rest-stress (82)Rb PET/CT myocardial perfusion imaging were developed and validated by evaluation of 281 patients (136 females: mean age +/- SD, 63.3 +/- 13.3 y; 145 males: mean age +/- SD, 63.9 +/- 12.8 y) who underwent a rest-adenosine stress (82)Rb PET/CT study. These patients were divided into 3 groups: (a) healthy group: 30 patients, with <5% likelihood of CAD (low likelihood [LLK]) based on sequential Bayesian analysis; these patients were used to generate the normal distribution; (b) pilot group: 174 patients; these patients were used to determine the optimal criteria for detecting and localizing the perfusion abnormality; and (c) validation group: 76 patients (23 with LLK of CAD and 53 who underwent coronary angiography; these patients were used for prospective validation. RESULTS: Of the 53 patients who underwent coronary angiography, 8 had <50% stenosis and 45 patients had at least one stenosis > or =50% in one major artery. Fifteen patients had single-vessel disease, 17 had double-vessel disease, and 13 had triple-vessel disease. The prospective validation shows a normalcy rate of 78% (18/23) for global CAD. The analyses by individual arteries show a normalcy rate of 96% (22/23) for the left anterior descending coronary artery, 96% for the left circumflex coronary artery (22/23), and 100% for the right coronary artery (23/23). The overall sensitivity for detection of CAD (> or =50% stenosis) was 93% (42/45). The overall specificity for detection of the absence of CAD (< or =50% stenosis) was 75% (6/8). Also, the positive predictive value for global CAD was 95% (42/44), the negative predictive value was 67% (6/9), and the accuracy was 91% (48/53). CONCLUSION: The quantitative (82)Rb PET/CT database created and validated in this study is highly accurate for the detection and localization of CAD. Physicians should consider using the quantitative output of these algorithms as decision support tools to aid with image interpretation.  相似文献   
33.
Prognostic factors in hormone-resistant progressing cancer of the prostate.   总被引:2,自引:0,他引:2  
In 224 consecutive patients with hormone-resistant prostatic cancer referred to 2 European Cancer Centres for palliation of painful bone metastases the one year survival for all patients was 24% (2-year survival: 7%). The median survival was 8 months. In univariate analyses the following prognostic factors were identified: performance status, serum creatinine, alkaline phosphatase, duration of response to primary hormone treatment, degree of bone scan involvement and hemoglobin. Multivariate analyses confirmed the four first parameters to be independent factors. A prognostic model was established (no or one risk factors vs 2 risk factors vs 3 or 4 risk factors) based on performance status, creatinine, alkaline phosphatase and hormone response duration. The median survival of these groups was 10 months, 6 months and 3 months, respectively. This model proved to be discriminative in an external data set of 214 patients with hormone-resistant prostatic cancer entered in two prospective trials. The above differences in outcome between readily and simply defined prognostic groups are greater than the differences one can realistically hope to produce using new treatment strategies. These prognostic factors should be taken into account both in the design and interpretation of clinical studies dealing with the treatment of hormone-resistant progressing prostatic cancer and painful bone metastases.  相似文献   
34.
Autologous seeding of vascular grafts has been in use since 1972; however, the fate of seeded cells has never been determined. While short-term retention has been determined by radioactively labeling cells, long-term studies of seeded cells have not been possible due to the lack of an appropriate marker system. We have developed a long-term marker system for endothelial cells by transfecting the cells with bacterial genes that can be detected by fluorescentally-labeled antibodies to these markers. Two bacterial genes, neo and cat both carried by a pSV2 plasmid construct were used to co-transfect cells. Transfects were selected by growth in the presence of G418. Transfected clones were expanded into monolayers that stained positive for cat by fluorescence, and retained the normal cobblestone morphology and factor VIII staining of endothelial cells. By stably transfecting cells with bacterial genes these cells can now be used to seed vascular grafts and follow the long-term fate of seeded cells.  相似文献   
35.
A group of destructive changes occurring in jaws in patients with maxillary complete dentures and mandibular removable partial dentures (bilaterally) has been described in the literature as the combination syndrome. However, this condition is not clinically observed in all patients. The aim of this study was to establish the prevalence index on signs of combination syndrome and to verify whether these changes also occurred in patients rehabilitated with a mandibular removable partial denture (unilaterally). Sample was composed of 44 patients, completely edentulous in the maxilla. Thirty-two patients had a Kennedy Class I removable partial denture and 12 a Kennedy Class II. Three major alterations were observed in 20.5% of the studied population. Nevertheless, these changes were present only in 25% of patients with Kennedy Class I removable partial denture. Based on the findings of this study, it can be concluded that patients with Kennedy Class II removable partial denture do not have similar signs that lead to the combination syndrome’s condition.  相似文献   
36.
PURPOSE: The purpose of this study was to determine the effect of aquatic therapy (AT) as an adjunct to home-based early intervention (EI) on differences in children's functional mobility. METHODS: Thirty-seven children of ages six to 30 months (x = 24.2; SD = 8.5) with delayed functional mobility participated in this study. The AT group (n = 15) received weekly AT in a community pool in addition to home-based EI with a physical therapist (PT) or occupational therapist (OT). A randomly selected comparison group (n = 22) received home-based EI with a PT or OT. Baseline and postintervention scores on the Gross Motor Subsection of the Mullen Scales of Early Learning were compared between the AT and comparison group. RESULTS: The AT group demonstrated significantly greater (p < 0.05) gains in functional mobility than the comparison group. CONCLUSION: AT is a useful adjunct to EI to improve children's functional mobility.  相似文献   
37.
In conclusion, plasma levels of the endothelialderived vasoconstrictor endothelin-1 (but not those of other neurohormonal vasoconstrictor factors), measured during exercise correlated closely with objective variables of exercise capacity in patients with heart failure. These findings suggest that endothelin-1 may contribute to exercise intolerance in patients with heart failure, perhaps by limiting the ability of the peripheral vasculature to dilate during exercise.  相似文献   
38.
To determine if dexamethasone has a role in the treatment of meningeal leukemia, 8 consecutive patients with acute lymphoblastic and signs or symptoms of CNS were included in the study. After the confirmation of leukemic blast cells on cerebrospinal fluid, they received intrathecal and IV dexamethasone; 3 days later the patients received “triple” intrathecal chemotherapy with dexamethasone, methotrexate and cytarabine, and the spinal fluid was studied again. All patients had good clinical response and 7 out of the 8 patients showed reduction on the CSF cell count after the use of dexamethasone alone. The results suggest that dexamethasone is a lympholytic agent that could play a more active role in the prevention and therapy of meningeal leukemia and should be preferred over hydrocortisone in the so called “triple” intrathecal chemotherapy for the prevention and treatment of CNS leukemia. © 1995 Wiley-Liss, Inc.  相似文献   
39.
40.
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