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   4958篇
  免费   246篇
  国内免费   32篇
耳鼻咽喉   41篇
儿科学   140篇
妇产科学   205篇
基础医学   553篇
口腔科学   148篇
临床医学   365篇
内科学   1232篇
皮肤病学   27篇
神经病学   548篇
特种医学   135篇
外科学   815篇
综合类   26篇
一般理论   1篇
预防医学   219篇
眼科学   70篇
药学   204篇
中国医学   2篇
肿瘤学   505篇
  2023年   20篇
  2022年   56篇
  2021年   120篇
  2020年   79篇
  2019年   109篇
  2018年   115篇
  2017年   105篇
  2016年   95篇
  2015年   127篇
  2014年   142篇
  2013年   237篇
  2012年   320篇
  2011年   298篇
  2010年   182篇
  2009年   189篇
  2008年   301篇
  2007年   291篇
  2006年   294篇
  2005年   293篇
  2004年   274篇
  2003年   243篇
  2002年   208篇
  2001年   79篇
  2000年   76篇
  1999年   88篇
  1998年   49篇
  1997年   41篇
  1996年   34篇
  1995年   28篇
  1994年   23篇
  1993年   20篇
  1992年   65篇
  1991年   46篇
  1990年   60篇
  1989年   51篇
  1988年   47篇
  1987年   56篇
  1986年   40篇
  1985年   45篇
  1984年   25篇
  1983年   25篇
  1982年   18篇
  1981年   17篇
  1980年   21篇
  1979年   21篇
  1978年   14篇
  1977年   22篇
  1974年   13篇
  1973年   13篇
  1972年   13篇
排序方式: 共有5236条查询结果,搜索用时 15 毫秒
991.
BACKGROUND: This study was conducted to evaluate the effects of levonorgestrel administration for emergency contraception (EC) on bleeding pattern and pituitary-ovarian function. STUDY DESIGN: In 69 women with a reported stable menstrual cycle length of 24-34 days, we investigated bleeding patterns following EC administration in the follicular (n=26), periovulatory (n=14) and luteal (n=29) phase. In a subgroup of 8 women, hormonal evaluation and ultrasonography were performed. RESULTS: EC taken in the follicular, but not in the periovulatory or luteal phase, significantly shortened cycle length by 10.9+/-1 days. The subsequent cycle was not affected. EC taken in the late preovulatory phase, prior to the gonadotrophin surge, suppressed ovulation (n=7), while ovulation was not blocked when EC was given during an ongoing luteinizing hormone (LH) pulse (n=1). CONCLUSIONS: Our data indicate that EC given before the onset of the luteinizing hormone (LH) surge inhibits ovulation and hastens the end of the current menstrual cycle. Subsequently, the length of the following menstrual cycle returned as prior to treatment. By contrast, levonorgestrel administered after the expected ovulation has no effect on menstrual cycle length.  相似文献   
992.
OBJECTIVE: To estimate the prevalence of physical violence and its association with sociodemographic aspects, stressful life events, and the use of health services due to emotional problems. METHODS: A cross-sectional population-based study was conducted with a sample of 1,954 14-year-old or older inhabitants of the city of Canoas (Southern Brazil). They were selected by means of conglomerate sampling according to a pre-established system. Data were obtained in visits to households by means of a confidential semi-structured questionnaire. A bivariate analysis was carried out through multinomial logistic regression, and the multivariate analysis by polytomous logistic regression, categorizing the outcome by age group. RESULTS: The findings show a prevalence of 9.7% (CI 95%: 8.37;11.03) and association with: women 20 years old and older (OR=2.74; CI 95%: 1.52;4.94); higher schooling rate (p<0.03); higher experience of stressful life events at 20 years of age or more (OR=6.61; CI 95%: 2.71;16.1); and doctors' appointments due to emotional problems as of 10 years of age (p>0.001). CONCLUSIONS: The prevalence of physical violence in the population was significant, resulting in important emotional consequences and impact on health services, requiring capacity building of the professionals in the field.  相似文献   
993.
994.
Based on the protective effects of cooked dry bean consumption in a human intervention study, we evaluated which fraction of cooked dry beans is responsible for its cancer-preventive effects. Cooked navy beans (whole beans), the insoluble fraction (bean residue) or soluble fraction of the 60% (vol:vol) ethanol extract of cooked navy beans (bean extract), or a modified AIN-93G diet (16.6% fat including 12.9% lard) as control diet were fed to 160 male obese ob/ob mice after 2 azoxymethane injections. In comparison to control-fed mice, dysplasia, adenomas, or adenocarcinomas were detected in fewer mice on either bean fraction diet (percent reduction from control: whole beans 54%, P=0.10; bean residue 81%, P=0.003; bean extract 91%, P=0.007), and any type of colon lesions, including focal hyperplasia, were found in fewer mice on each of the 3 bean diets percent reduction from control: whole bean 56%, P=0.04; bean residue 67%, P=0.01; bean extract 87%, P=0.0003. These results suggest that both the soluble and the insoluble fraction of the extract contribute to the cancer-protective effect of cooked navy beans.  相似文献   
995.
996.

BACKGROUND:

Patients affected by relapsed or primary refractory lymphomas currently have a poor prognosis and no standard salvage treatment options. This study was carried out to assess the efficacy and safety of a dexamethasone, high‐dose cytarabine, and oxaliplatin as salvage therapy in those patients, replacing cisplatin with oxaliplatin in the standard dexamethasone, cytarabine, and cisplatin scheme.

METHODS:

Seventy patients with relapsed or refractory aggressive non‐Hodgkin or Hodgkin lymphoma were treated from September 2001 to September 2007. The median age of patients was 51 years (range, 19‐75 years). Histological subtypes were: diffuse large B‐cell lymphoma (n = 47) and Hodgkin lymphoma (n = 23). The overall response rate was 73% (51 of 70), with 30 (43%) complete remissions and 21 (30%) partial remissions. Fifty‐two patients were treated with dexamethasone, high‐dose cytarabine, and oxaliplatin as second‐line chemotherapy. Forty‐eight patients were enrolled in an autologous stem cell transplantation program; forty (83%) finally proceeded to high‐dose consolidation and autografting.

RESULTS:

No grade 3 or 4 nonhematological toxicity was demonstrated; in particular, no renal or neurotoxicity was reported. After a median follow‐up period of 21 months (range, 2‐87 months), 22 (31%) patients had died. Probabilities of 2‐year progression‐free survival (PFS) and overall survival (OS) were 44% and 71%, respectively. In the chemosensitive patients, the PFS and OS were 52% and 83%, respectively. The only factor that significantly correlated with better OS was the response to therapy.

CONCLUSIONS:

This study confirms that dexamethasone, high‐dose cytarabine, and oxaliplatin ± rituximab is an effective and feasible outpatient regimen for salvage therapy in patients affected by relapsed or refractory lymphoma. Moreover, the feasibility and efficacy of this scheme as an in vivo chemosensitive test in patients in autotransplantation programs was confirmed. Cancer 2010. © 2010 American Cancer Society.  相似文献   
997.
Jedrychowski WA, Perera FP, Maugeri U, Mroz E, Klimaszewska‐Rembiasz M, Flak E, Edwards S, Spengler JD. Effect of prenatal exposure to fine particulate matter on ventilatory lung function of preschool children of non‐smoking mothers. Paediatric and Perinatal Epidemiology 2010. Impaired fetal development is associated with a number of adult chronic diseases and it is believed that these associations arise as a result of the phenomenon of prenatal programming, which involves persisting changes in structure and function of various body organs caused by ambient factors during critical and vulnerable periods of early development. The main goal of the study was to assess the association between lung function in early childhood and prenatal exposure to fine particulate matter (PM2.5), which represents a wide range of chemical compounds potentially hazardous for fetal development. Among pregnant women recruited prenatally to the study, personal measurements of PM2.5 were performed over 48 h in the second trimester of pregnancy. After delivery, infants were followed for 5 years; the interviewers visited participants in their homes to record children's respiratory symptoms every 3 months in the child's first 2 years of life and every 6 months thereafter. In the fifth year of the follow‐up, children were invited for standard lung function testing of levels of forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1) and forced expiratory volume in 0.5 s (FEV0.5). There were 176 children of non‐smoking mothers, who performed at least two acceptable spirometry measurements. Multivariable linear regression showed a significant deficit of FVC at the highest quartile of PM2.5 exposure (beta coefficient = ?91.9, P = 0.008), after adjustment for covariates (age, gender, birthweight, height and wheezing). Also FEV1 level in children was inversely correlated with prenatal exposure to PM2.5, and the average FEV1 deficit amounted to 87.7 mL (P = 0.008) at the higher level of exposure. Although the effect of PM2.5 exposure on FEV0.5 was proportionally weaker (?72.7, P = 0.026), it was also statistically significant. The lung function level was inversely and significantly associated with the wheezing recorded over the follow‐up. The findings showed that significant lung function deficits in early childhood are associated with prenatal exposure to fine particulate matter, which may affect fetal lung growth.  相似文献   
998.
Coronary artery bypass grafting (CABG) continues to be one of the most commonly performed cardiac surgical procedures worldwide. Conventional CABG performed on cardiopulmonary bypass termed on-pump CABG is regarded as the gold standard. However, on-pump CABG results in several physiologic derangements including but not limited to thrombocytopenia, activation of complement factors, immune suppression, and inflammatory responses leading to organ dysfunction. Furthermore, manipulating an atherosclerotic ascending aorta during cannulation and cross-clamping can predispose to embolization and stroke risk. Recognition of these detrimental effects of on-pump CABG resulted in resurgence of off-pump CABG nearly two decades ago. Off-pump CABG since its resurgence has been a subject of intensive scrutiny and speculation. Despite numerous retrospective nonrandomized studies, prospective randomized trials, and meta-analyses validating the safety and efficacy of off-pump CABG, opponents of the technique have persistently demanded abandonment of off-pump CABG. Several misconceptions and misperceptions are used as an excuse for such demands. This review article examines published scientific evidence to evaluate these misperceptions and misconceptions about off-pump CABG.  相似文献   
999.
Focal epithelial hyperplasia(FEH), or Heck's disease, is a rare disease of the oral mucosa; it is mostly found in children or young adults who are immunosuppressed and who live in regions with low socioeconomic status. It is characterized by asymptomatic papules on the oral mucosa, gingiva, tongue, and lips. Healing can be spontaneous, and treatment is indicated if there are aesthetic or functional complications. Human papillomavirus, especially genotypes 13 and 32, has been associated with FEH and is detected in the majority of lesions. Histopathologically, FEH is characterized by parakeratosis, epithelial hyperplasia, focal acanthosis, and fusion and horizontal outgrowth of epithelial ridges. A 37-year-old male patient was referred to the Department of Oral and Maxillofacial Sciences at the Sapienza University of Rome, complaining of numerous exophytic lesions in his mouth. He stated that the lesions were not painful but he had experienced occasional bleeding after incidental masticatory trauma. He had received no previous treatment for the oral lesions. His medical history revealed that he was human immuno-deficiencyvirus positive and was a smoker with numerous, asymptomatic oral papules clinically and histologically corresponding to FEH. The labial and buccal mucosa were especially affected by lesions. Surgical treatment was performed using a 532-nm potassium titanyl phosphate laser(SmartLite, Deka, Florence, Italy) in continuous mode with a 300 μm fiber and power of 1.4 W(power density 1980.22 W/cm2). After anesthesia without vasoconstrictors, the lesions were tractioned with sutures or an Allis clamp and then completely excised. The lesions were preserved in 10% formalin for histological examination, which confirmed the clinical diagnosis of FEH. In this case, the laser allowed excellent control of bleeding, without postoperative sutures, and optimal wound healing.  相似文献   
1000.

Purpose  

Nitric oxide (NO) intrauterine production has been shown to have an important role in the reproductive system in females. The objective of the present study was to evaluate NO concentration in endometrial washing throughout the menstrual cycle.  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