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   11083篇
  免费   865篇
  国内免费   62篇
耳鼻咽喉   57篇
儿科学   314篇
妇产科学   324篇
基础医学   1197篇
口腔科学   150篇
临床医学   1433篇
内科学   1859篇
皮肤病学   252篇
神经病学   1041篇
特种医学   357篇
外科学   1437篇
综合类   247篇
一般理论   12篇
预防医学   1398篇
眼科学   174篇
药学   1049篇
中国医学   20篇
肿瘤学   689篇
  2023年   59篇
  2022年   92篇
  2021年   219篇
  2020年   136篇
  2019年   226篇
  2018年   243篇
  2017年   217篇
  2016年   243篇
  2015年   262篇
  2014年   342篇
  2013年   492篇
  2012年   732篇
  2011年   758篇
  2010年   402篇
  2009年   376篇
  2008年   657篇
  2007年   765篇
  2006年   725篇
  2005年   791篇
  2004年   714篇
  2003年   621篇
  2002年   590篇
  2001年   208篇
  2000年   174篇
  1999年   223篇
  1998年   154篇
  1997年   131篇
  1996年   100篇
  1995年   93篇
  1994年   74篇
  1993年   80篇
  1992年   113篇
  1991年   96篇
  1990年   83篇
  1989年   72篇
  1988年   50篇
  1987年   72篇
  1986年   66篇
  1985年   69篇
  1984年   54篇
  1983年   50篇
  1982年   37篇
  1981年   31篇
  1980年   25篇
  1979年   29篇
  1978年   24篇
  1976年   29篇
  1975年   23篇
  1974年   28篇
  1973年   19篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
121.
BACKGROUND: Tubulitis is a defining feature of renal allograft rejection. Graft dysfunction may result from damage inflicted on tubular epithelial cells by intratubular cytotoxic T lymphocytes. Graft cells are known to produce chemokines during acute rejection, but it is not known whether changes in expression of specific chemokines can influence the composition of the intratubular lymphocyte population. We examined expression of individual chemokines in biopsy sections showing different pathological rejection grades. METHODS: Sections from Banff-graded transplant biopsies were examined for the presence of beta-chemokines (MCP-1, MIP-1alpha, MIP-1beta, and RANTES) by immunofluorescence and semiquantitative confocal laser scanning microscopy. RESULTS: Beta-chemokines were expressed predominantly at the basolateral surface of tubular epithelial cells. Expression of MCP-1 and MIP-1beta was significantly higher in sections showing grade 2 rather than grade 1 acute rejection. RANTES and MIP-1alpha showed no significant variation in level of expression between rejection grades. CONCLUSIONS: Beta-chemokines are expressed by tubular epithelial cells during acute rejection. Consistent expression of RANTES and MIP-1alpha suggests a general role in recruiting T lymphocytes. However, MCP-1 and MIP-1beta may play a more subtle role in recruitment of specific T-cell subsets, such as Th1 cells, during acute cellular rejection.  相似文献   
122.
PURPOSE: Localized pancreatic carcinoma is rarely resectable and is resistant to conventional therapies. ONYX-015 (dl1520) is an E1B-55kD gene-deleted replication-selective adenovirus that preferentially replicates in and kills malignant cells. Endoscopic ultrasound (EUS) has the potential to conveniently and accurately deliver local therapy to the pancreas. Therefore, we undertook a trial of the feasibility, tolerability, and efficacy of EUS injection of ONYX-015 into unresectable pancreatic carcinomas. EXPERIMENTAL DESIGN: Twenty-one patients with locally advanced adenocarcinoma of the pancreas or with metastatic disease, but minimal or absent liver metastases, underwent eight sessions of ONYX-015 delivered by EUS injection into the primary pancreatic tumor over 8 weeks. The final four treatments were given in combination with gemcitabine (i.v., 1,000 mg/m(2)). Patients received 2 x 10(10) (n = 3) or 2 x 10(11) (n = 18) virus particles/treatment. RESULTS: After combination therapy, 2 patients had partial regressions of the injected tumor, 2 had minor responses, 6 had stable disease, and 11 had progressive disease or had to go off study because of treatment toxicity. No clinical pancreatitis occurred despite mild, transient elevations in lipase in a minority of patients. Two patients had sepsis before the institution of prophylactic oral antibiotics. Two patients had duodenal perforations from the rigid endoscope tip. No perforations occurred after the protocol was changed to transgastic injections only. CONCLUSIONS: This study indicates that ONYX-015 injection via EUS into pancreatic carcinomas by the transgastic route with prophylactic antibiotics is feasible and generally well tolerated either alone or in combination with gemcitabine. Transgastric EUS-guided injection is a new and practical method of delivering biological agents to pancreatic tumors.  相似文献   
123.
OBJECTIVE: This study aims to establish normal values for nucleated red blood cells in term singletons and factors associated with their elevation.STUDY DESIGN: Cord blood was prospectively collected from term singleton gestations from Feb. 1 to July 31, 1995. Umbilical vein white blood cells and nucleated red blood cells were counted and umbilical arterial pH was determined. Medical records provided maternal and neonatal information.RESULTS: Cord blood from 1112 cases was obtained and evaluated for nucleated red blood cells per 100 white blood cells. Nine outliers were censored (nucleated red blood cells per 100 white blood cells = 126 to 830); five cases were excluded because of missing data. The mean value of nucleated red blood cells per 100 white blood cells was 8.55, the SD was 10.27, and the range was 0 to 89. The value did not vary by maternal tobacco or drug use, anemia, fetal presentation, or mode of delivery. Both maternal diabetes and meconium were associated with elevated values, p < 0.01. Apgar scores and cord pHs showed trends toward inverse proportionality to the number of nucleated red blood cells per 100 white blood cells.CONCLUSION: The mean number of nucleated red blood cells per 100 white blood cells was 8.55, with a wide range and SD. Elevated values may be associated with markers of intrauterine hypoxia such as meconium, lower Apgar scores, and lower pH values. (Am J Obstet Gynecol 1997;176:1149-56.)  相似文献   
124.
Purpose: A single-institution phase II trial of Temodal (temozolomide, SCH52365) in Chinese patients with advance nasopharyngeal carcinoma was undertaken to determine the efficacy and safety of the drug in this population. Methods: A total of 14 patients with metastatic or locoregionally recurrent nasopharyngeal carcinoma were entered into the study. One patient was unevaluable. Temodal was given at doses of 150 or 200 mg/m2 daily on days 1–5 every 28 days. Results: In all, 30 cycles of Temodal were given with no significant toxicity. All 13 (100%) evaluable patients had progressive disease after 2 (84.6%) or 4 (15.4%) courses. Conclusion: Temodal given on this schedule has no activity in advanced nasopharyngeal carcinoma. Received: 9 January 1998 / Accepted: 4 February 1998  相似文献   
125.
126.
This editorial explores the way in which mental health investigations are developing in England and in particular those involving a homicide. A move away from traditional panel inquiries and towards investigations using root cause analysis (RCA) is aimed at shifting the focus from individual blame to identifying system failure. Thus it is envisaged by policy makers that the RCA approach will offer greater learning opportunities for mental health services. The key difficulties associated with panel inquiries are highlighted before describing the intended benefits of the RCA approach. Finally, five key areas where systematic research can support the development of this approach are suggested.  相似文献   
127.
There were 57 infectious diseases notifiable at the national level in Australia in 2002. States and territories reported 100,278 cases of infectious diseases to the National Notifiable Diseases Surveillance System (NNDSS), a fall of 4 per cent compared to the number of notifications in 2001. In 2002, the most frequently notified diseases were, sexually transmitted infections (31,929 reports, 32% of total notifications), gastrointestinal infections (26,708 reports, 27% of total notifications) and bloodborne infections (23,741, 24%). There were 11,711 (12% of total) cases of vaccine preventable diseases, 3,052 (3% of total) cases of vectorborne diseases, 1,155 (1% of total) cases of zoonotic infections, two cases of quarantinable diseases (Vibrio cholerae O1) and 1,980 cases of other bacterial diseases, notified to NNDSS. Compared to 2001, notifications of sexually transmitted infections increased by 16 per cent and gastrointestinal infections by 2 per cent while bloodborne infections fell by 18 per cent. The number of notifications of chlamydial infection and Q fever were the highest since 1991 and 1995 respectively. By contrast, the number of notification for hepatitis A and measles were the lowest since 1991. For other notifiable diseases, the number of notifications was within the range of the five years between 1997 and 2002 (range = five-year mean plus or minus two standard deviations). This report also includes 2002 summary data on communicable diseases from other surveillance systems including the Laboratory Virology and Serology Reporting Scheme and sentinel general practitioner schemes.  相似文献   
128.
Stillbirth occurs in nearly 1% of all births in the USA, and is one of the most common but least studied adverse pregnancy outcomes. The many risk factors for and causes of stillbirth are presented. Over the past several decades, the rate of stillbirth has been substantially reduced, with the reduction most apparent in those stillbirths previously occurring at term and/or in labor. Reductions have occurred because of reductions in risk factors (i.e. prevention of Rh disease and better control of diabetes), better antepartum monitoring of those with risk factors followed by early delivery for those fetuses found to be at risk (i.e. growth restriction, maternal pre-eclampsia), better intrapartum fetal monitoring, increases in Cesarean section for those at risk, and early detection of congenital anomalies followed by termination prior to the time that these early fetal deaths are classified as stillbirths. Finally, the value of using fetal autopsy and placental examination to determine the cause of death accurately, both for research purposes and for patient counseling in future pregnancies, is explored.  相似文献   
129.
Overweight and obesity-related metabolic disorders in hospital employees.   总被引:1,自引:0,他引:1  
BACKGROUND: Obesity is associated with metabolic disorders and cardiovascular diseases. This study investigated the relationship between overweight and obese status and the incidence of type 2 diabetes, hypertension, hyperlipidemia and hyperuricemia. METHODS: This prospective cohort study comprised 1749 hospital employees who received baseline health check-ups in 1993. Data from the 1027 participants (832 women, 195 men; mean age, 36 +/- 7 years) who repeated check-ups in 2003 were used in the analysis. Relative risks (RRs) for development of metabolic disorders during follow-up associated with different body mass index (BMI) categories at baseline as defined by Asia-Pacific recommendations and the Department of Health in Taiwan were calculated after adjustment for covariates. RESULTS: The prevalence of overweight and obesity at baseline check-up were 17.6% and 14.5%, respectively. Obese subjects with baseline BMI >or= 25 kg/m2 had a significant multivariate-adjusted RR of 2.7 for hypertension, 14.8 for type 2 diabetes, 3.2 for hypertriglyceridemia, and 2.8 for hyperuricemia, compared to subjects with baseline BMI < 23.0 kg/m2. RR for diabetes was higher in women than in men, but RR for hypertriglyceridemia was higher in men. The risks of hypertension and hyperuricemia significantly increased for subjects with baseline BMI >or= 23 kg/m2, while RRs for type 2 diabetes increased significantly for baseline BMI >or= 24 kg/m2 and hypertriglyceridemia increased for baseline BMI >or= 25 kg/m2. The risks attributable to obesity (baseline BMI >or= 25 kg/m2) were 23.0% for hypertension, 70.8% for diabetes, 27.9% for hypertriglyceridemia, and 24.1% for hyperuricemia. CONCLUSION: This study revealed that a high prevalence of overweight and obesity was associated with significantly increased risk of development of type 2 diabetes, hypertension, hypertriglyceridemia and hyperuricemia in hospital employees, suggesting the need for programs to improve weight management.  相似文献   
130.
Richards  H.  L.  Ray  D.  W.  Kirby  B.  C.E.M.  Griffiths  刘艳 《世界核心医学期刊文摘》2006,2(3):36-36
背景:应激可能会触发和(或)加重一些银屑病患者的病情。目的:下丘脑-垂体-肾上腺(HPA)轴的激活是有效应激反应的关键,本文以银屑病患者为对象研究此关系。方法:40例慢性斑块型银屑病患者与40例年龄匹配的正常对照者,随机经历3种急性心理应激(认知、情感与社会应激)。在基线时及每次应激后,连续检测血浆皮质激素、脉率和血压。在检测日9:00,收集唾液皮质激素标本。结果:对照者经历社会应激后,脉率与血浆皮质激素水平显著相关(r=0.38;P〈0.05);而银屑病患者则无此联系(r=0.07;无显著性)。  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