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   9210篇
  免费   921篇
  国内免费   3篇
耳鼻咽喉   90篇
儿科学   163篇
妇产科学   177篇
基础医学   1367篇
口腔科学   220篇
临床医学   1028篇
内科学   1882篇
皮肤病学   93篇
神经病学   1014篇
特种医学   399篇
外科学   1128篇
综合类   182篇
一般理论   3篇
预防医学   986篇
眼科学   299篇
药学   565篇
中国医学   10篇
肿瘤学   528篇
  2021年   169篇
  2020年   99篇
  2019年   160篇
  2018年   155篇
  2017年   129篇
  2016年   125篇
  2015年   149篇
  2014年   214篇
  2013年   319篇
  2012年   533篇
  2011年   466篇
  2010年   265篇
  2009年   231篇
  2008年   438篇
  2007年   413篇
  2006年   418篇
  2005年   393篇
  2004年   388篇
  2003年   336篇
  2002年   364篇
  2001年   269篇
  2000年   214篇
  1999年   205篇
  1998年   102篇
  1997年   94篇
  1996年   106篇
  1995年   90篇
  1994年   79篇
  1993年   71篇
  1992年   221篇
  1991年   192篇
  1990年   191篇
  1989年   200篇
  1988年   185篇
  1987年   171篇
  1986年   154篇
  1985年   167篇
  1984年   146篇
  1983年   125篇
  1982年   75篇
  1981年   67篇
  1980年   71篇
  1979年   110篇
  1978年   93篇
  1977年   85篇
  1975年   74篇
  1974年   86篇
  1973年   83篇
  1972年   74篇
  1970年   74篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
OBJECTIVE: The purpose of this study was to delineate the prevalence, demographic characteristics, comorbidity, hospitalization, and medication use of a large cohort of patients with and without multiple episodes per year. We hypothesized that children and adolescents with multiple episodes per year would have a higher comorbidity and require more hospitalizations and pharmacological treatment than their counterparts without multiple episodes. METHODS: Analysis was conducted on a cohort of 8,129 children and adolescents patients (< or = 18 y.o.) with bipolar disorders (BD), from the Integrated Healthcare Information Services (IHCIS) identified from June 30, 2000 to July 1, 2003. Demographics variables, type of hospitalization, and psychotropic medication used in the year of follow-up were compared between children and adolescents with multiple and those without multiple episodes per year. RESULTS: Included were 58 patients with multiple episodes (defined as: > or = 4 or more reports of inpatient treatment for any affective disorders per year) and 8,071 without multiple episodes. Children and adolescents with multiple episodes versus those without multiple episodes were differentiated as follows: more comorbid attention deficit disorder (ADD) (80.9% versus 29.4%) (chi2 = 70.61, df = 1, p < 0.0001); higher rate of hospital admission for depression (12.1% vs. 1.8%, chi2 = 27.86, df = 1, p < 0.0001); for other psychiatric conditions (48.3% vs. 11.2, chi2 = 74.47, df = 1, p < 0.0001) and for medical conditions (22.4% vs. 3.9%, chi2 = 46.26, df = 1, p < 0.0001). Patients with multiple episodes per year were more likely than those without multiple episodes to be given mood stabilizers (91.4% vs. 60.3%, chi2 = 22.02, df = 1, p < 0.0001), antidepressants (79.3% vs. 59.2%, chi2 = 8.82, df = 1, p = .0003), and antipsychotics (89.7% vs. 45.8%, chi2 = 42.91, df = 1, p < 0.0001). The use of stimulants did not differ between the two groups (24.1% vs. 23.0%), chi2 = 0.02, df = 1, p = 0.96). CONCLUSIONS: Our findings support previous studies demonstrating that children and adolescents with multiple episodes per year present a higher comorbidity and require more hospitalizations and pharmacological treatment than those without multiple episodes. The diagnosis and treatment of children and adolescents with BD will have to take into account the high comorbidity of ADD mainly in children and adolescents with multiple episodes. Future prospective studies will help to better characterize the impact of multiple episodes in the course of pediatric BD and facilitate appropriate treatment strategies.  相似文献   
992.
993.
This paper clarifies and updates some issues of life expectancy in cerebral palsy. These are: (1) the definition of life expectancy and how it is calculated; (2) the secular trends that have occurred since the data for the 1998 paper were collected; (3) revised estimates reflecting improvements of some of the analytical methods and statistics provided in that paper; (4) comparison of life expectancies among countries; (5) issues regarding quality of care; and (6) consideration of prospective life expectations in addition to current life expectancy.  相似文献   
994.
995.
Mountain lion attacks on humans are rare and potentially fatal. Although few victims experience minor injuries, permanent disfigurement and disability is common among survivors of these assaults. Since 1986, a steady number of mountain lion attacks have been noted in California. We report a recent attack of a cougar on a couple hiking in California's Prairie Creek Redwoods State Park. The victim sustained a significant scalp injury that led to a life-threatening soft-tissue infection. We present an analysis of the injury pattern as it relates to the bite marks, the resulting degloving injury, and the surgical reconstruction. We also offer a current survey of the pathogens often found in cats' and mountain lions' bite wounds and the appropriate antibiotic treatment. Given the infrequency at which clinicians encounter mountain lion injuries, we recommend that after initial management and exclusion of life threatening injuries patients be transferred to a tertiary care facility capable of managing the various reconstructive challenges such as the one presented in this case.  相似文献   
996.
BACKGROUND: Our objectives were to determine the incidence of acute and late toxicities and to estimate the 2-year overall survival for patients treated with reirradiation and chemotherapy for unresectable squamous cell carcinoma of the head and neck (SCCHN). METHODS: Patients with recurrent squamous cell carcinoma or a second primary arising in a previously irradiated field were eligible. Four weekly cycles of 5-fluorouracil 300 mg/m2 IV bolus and hydroxyurea 1.5 g by mouth were used with 60 Gy at 1.5 Gy twice-daily fractions. Toxicity was scored according to Radiation Therapy Oncology Group/European Organization for Research and Treatment of Cancer (RTOG/EORTC) criteria. RESULTS: Seventy-nine of the 86 patients enrolled were analyzable. The worst acute toxicity was grade 4 in 17.7% and grade 5 in 7.6%. Grade 3 and 4 late toxicities were found in 19.4% and 3.0%, respectively. The estimated cumulative incidence of grade 3 to 4 late effects occurring at >1 year was 9.4% (95% confidence interval [CI]: 0, 19.7) at 2 and 5 years. The 2- and 5-year cumulative incidence for grade 4 toxicity was 3.1% (95% CI: 0, 9.3). The estimated 2- and 5-year survival rates were 15.2% (95% CI: 7.3, 23.1) and 3.8% (95% CI: 0.8, 8.0), respectively. Patients who entered the study at >1 year from initial radiotherapy (RT) had better survival than did those who were <1 year from prior RT (median survival, 9.8 months vs 5.8 months; p = .036). No correlation was detected between dose received and overall survival. Three patients were alive at 5 years. CONCLUSION: This is the first prospective multi-institutional trial testing reirradiation plus chemotherapy for recurrent or second SCCHN. The approach is feasible with acceptable acute and late effects. The results serve as a benchmark for ongoing RTOG trials.  相似文献   
997.
This study evaluated the effect of heart failure (HF) and ejection fraction (EF) at baseline on long-term cardiac mortality in patients undergoing coronary revascularization and investigated the effect of diabetes mellitus (DM) on mortality. We evaluated long-term outcomes of patients without HF, HF and a preserved EF, and HF and a decreased EF who underwent revascularization with percutaneous transluminal coronary angioplasty or coronary artery bypass graft surgery after enrollment in the Bypass Angioplasty Revascularization Investigation (BARI) trial. Ten years after initial revascularization, cumulative rates of freedom from cardiac death were 90% in patients without HF, 75% in patients with HF and a preserved EF, and 59% in patients with HF and a decreased EF (p <0.001, 3-way comparison). In diabetic patients with HF and a preserved EF, there was a significant increase in cardiac mortality compared with patients without HF (p <0.001); however, this relation was not seen in patients without DM. In conclusion, patients with HF and a preserved EF have increased mortality over 10 years compared with those without HF. Only in patients with DM did HF with preserved EF confer additional risk.  相似文献   
998.
Relief from pain in humans is frequently measured by computing the reduction on an 11-point pain intensity scale. However, this definition of relief may be insufficient to capture the utility of pain relief for the individual. Based on pain literature and evidence from studies examining relief and reward, it is clear that pain relief is a broad concept comprising several factors, only one of which is pain intensity reduction. According to opponent process theory, all sensations consist of a primary process and a slow 'opponent process' of opposite valence, the purpose of which is to reduce the deviation from homeostatic balance. Here, opponent process theory provided a framework to explore the interaction between pain, relief and reward. We devised three psychophysical studies examining the temporal (Experiment I) and magnitude (Experiments I and II) relationships between pain severity and its subsequent relief. In Experiment III, we further manipulated the magnitude and pleasantness of relief experienced by applying innocuous cooling following noxious heat stimulation of capsaicin-sensitized skin. Results confirmed predictions from opponent process theory and showed that pain intensity reduction was significantly stronger than relief intensity ratings. Furthermore, continuous relief ratings appeared to reflect the speed of pain intensity reduction. Varying pain intensity parametrically confirmed that relief increases with pain intensity. That innocuous cooling following primary hyperalgesia intervention significantly increased the intensity, pleasantness and duration of relief provides further evidence that pain relief encapsulates more than a reduction in pain intensity. Importantly, the high relief pleasantness ratings confirmed the hypothesized link between relief and reward.  相似文献   
999.
1000.
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