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   29985篇
  免费   2933篇
  国内免费   512篇
耳鼻咽喉   263篇
儿科学   776篇
妇产科学   382篇
基础医学   1581篇
口腔科学   812篇
临床医学   5717篇
内科学   3489篇
皮肤病学   271篇
神经病学   2263篇
特种医学   1091篇
外科学   3803篇
综合类   2579篇
一般理论   6篇
预防医学   5902篇
眼科学   205篇
药学   2703篇
  65篇
中国医学   602篇
肿瘤学   920篇
  2024年   52篇
  2023年   691篇
  2022年   1016篇
  2021年   1586篇
  2020年   1539篇
  2019年   1587篇
  2018年   1553篇
  2017年   1421篇
  2016年   1400篇
  2015年   1213篇
  2014年   2188篇
  2013年   2917篇
  2012年   1573篇
  2011年   1785篇
  2010年   1388篇
  2009年   1358篇
  2008年   1363篇
  2007年   1316篇
  2006年   1063篇
  2005年   975篇
  2004年   831篇
  2003年   700篇
  2002年   590篇
  2001年   553篇
  2000年   425篇
  1999年   330篇
  1998年   296篇
  1997年   257篇
  1996年   242篇
  1995年   200篇
  1994年   198篇
  1993年   126篇
  1992年   119篇
  1991年   96篇
  1990年   71篇
  1989年   65篇
  1988年   47篇
  1987年   49篇
  1986年   40篇
  1985年   53篇
  1984年   38篇
  1983年   18篇
  1982年   22篇
  1981年   18篇
  1980年   14篇
  1979年   11篇
  1978年   6篇
  1976年   5篇
  1975年   8篇
  1974年   4篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
81.
Between 23 and 70% of occupants involved in frontal impacts sustain cervical spine injuries, many with neurological involvement. It has been hypothesized that cervical spinal cord compression and injury may explain the variable neurological profile described by frontal impact victims. The goals of the present study, using a biofidelic whole cervical spine model with muscle force replication, were to quantify canal pinch diameter (CPD) narrowing during frontal impact and to evaluate the potential for cord compression. The biofidelic model and a sled apparatus were used to simulate frontal impacts at 4, 6, 8, and 10 g horizontal accelerations of the T1 vertebra. The CPD was measured in the intact specimen in the neutral posture (neutral posture CPD), under static sagittal pure moments of 1.5 Nm (pre-impact CPD), during dynamic frontal impact (dynamic impact CPD), and again under static pure moments following each impact (post-impact CPD). Frontal impact caused significant (P<0.05) dynamic CPD narrowing at C0-dens, C2-C3, and C6-C7. The narrowest dynamic CPD was observed at C0-dens during the 10 g impact and was 25.9% narrower than the corresponding neutral posture CPD. Interpretation of the present results indicate that the neurological symptomatology reported by frontal impact victims is most likely not due to cervical spinal cord compression. Cord compression due to residual spinal instability is also not likely.  相似文献   
82.
Abstract We report a case of SMV injury in a critically ill patient. The patient was a 19-year-old woman involved in a motor vehicle collision. Her injuries included grade II splenic and renal lacerations, devascularized and lacerated right and transverse colon, a transected transverse mesocolon, a massive shear injury of her abdominal wall, and two partial SMV transections. At initial damage control laparotomy, the SMV was ligated, the devascularized bowel resected and a temporary abdominal closure applied. At re-operation, a mesocaval shunt using saphenous vein was employed. The shunt failed and the patient required a saphenous vein jump graft. Although visceral vascular injuries are rare, ligation of the SMV in a damage control situation is acceptable. This case study is the first to discuss appropriate treatment when interruption to a patient's collateral visceral venous drainage limits the surgeon’s ability to ligate. In these situations, bypass shunts may be successful.  相似文献   
83.
As our world becomes increasingly multicultural in nature, multilingual skills constitute an everyday phenomenon in schools. Since most of the second-language research has focused on school-age students, more research had to be conducted with language-minority students at the kindergarten level in order for psychologists and educators to develop effective and efficient systems for evaluating and tracking the developmental status of young language-minority children. The purpose of this study was to investigate the potential usefulness of a standardized continuous progress measure, the Picture Naming Individual Growth and Development Indicator, to longitudinally assess language development in 23 language-minority children, as well as in 13 native English-speaking children. Results indicated that we could use the Picture Naming Individual Growth and Development Indicator to detect differences in first-language and second-language development in language-minority children, as well as to detect differences between the two groups of children in their expressive English-language skills.  相似文献   
84.
Introduction and Aims. Different self‐report methods tend to produce different estimates of alcohol consumption. The present study compares differences in rates and risk levels based on responses to a modified version of the Daily Drinking Questionnaire (m‐DDQ) and quantity‐frequency (QF) questions. Design and Methods. The sample comprised 2082 university students, 61% of whom were female and 39% male with a mean age of 23.5 years. An email containing an online link to a brief six‐question survey was emailed to students enrolled in participating faculties at the University of Wollongong, Australia. Current drinkers completed m‐DDQ and QF questions about alcohol consumption. Results. QF methods identified significantly lower estimates of consumption (Mean = 9.15, SD = 12.51) compared with m‐DDQ (Mean = 13.06, SD = 14.07). Allocation to risk categories based on the Australian Alcohol Guidelines were conducted for both the m‐DDQ and QF methods. Almost twice as many students were found to be drinking at levels considered risky using the m‐DDQ method compared with QF. In addition, the relative rank order of participants varied significantly between the two methods. Discussion and Conclusions. The m‐DDQ method identified higher rates of drinking and categorised almost twice as many individuals into risky categories of drinking compared with QF. Such variations have major implications for identification of risk groups in health promotion or prevention programs.[Utpala‐Kumar R, Deane FP. Rates of alcohol consumption and risk status among Australian university students vary by assessment questions. Drug Alcohol Rev 2009]  相似文献   
85.
86.
目的总结外伤性脑梗死的CT特征,探讨其发生机制,揭示其对疾病预后的判定价值。方法回顾性分析40例外伤性脑梗死患者头颅CT表现及相关临床资料。结果轻微外伤引起的脑梗死多发于儿童,好发部位为基底节内囊区,预后较好;重症外伤引起的脑梗死好发于成人,发病部位多见于颅内血肿同侧,且大脑后动脉支配区域最为多见,预后较差。结论CT扫描对外伤性脑梗死的诊断及预后判定有重要价值。  相似文献   
87.
OBJECTIVE: Colonic infarction is a recognized complication of abdominal aortic aneurysm (AAA) surgery. The clinical difficulty in establishing the diagnosis combined with the patient's poor physiological status is usually associated with a fatal outcome. We assessed our experience with this problem to identify a possible risk factor profile for these patients. METHOD: Patients records were identified from the operative logs, intensive care unit, Hospital Inpatient Enquiry system and vascular unit databases over a 6-year period. RESULTS: A total of 405 patients underwent AAA repair during this period; 140 as emergency ruptures. Nine patients were identified from the databases with known colonic infarction (2.2%). One was a woman. The mean age was 70 years. Seven patients had emergency ruptures (5%). Twenty independent risk factors were analysed using univariate and multivariate logistic regression models. Significant risk factors identified by using a multivariate analysis included the nature of the presenting patient, preoperative hypotension, prolonged cross-clamp time, intra-operative ischaemia and postoperative acidosis. Confirmatory diagnosis was made by colonoscopy in eight patients. One patient survived following the salvage surgery. The mean duration of survival was 10.5 days. The overall mortality was 89% of patients. CONCLUSION: In our unit infrarenal AAA repair has a 2.2% rate of colonic infarction. A definitive diagnosis is best made by colonoscopy. A risk factor profile for the development of colonic infarction may be constructed on the basis of specific clinical parameters. Earlier intervention on the basis of this profile may ultimately reduce the current excessive mortality.  相似文献   
88.
Objective To estimate the present salt iodine content and iodine nutrition need of high risk population of iodine deficiency disorder in Meixian County. Methods Each primary school was selected from urban and rural areas(Xiyang Town, 20 kilometers away from Meixian County), the goiter rate of 8 to 10 year-old students was examined and urinary iodine and household salt iodine was sampled. Twenty to 40 year-old women of childbearing age nearby schools around the urban and villages around Xiyang Town were selected to collect their urine and salt samples. At urban hospitals and rural health centers, 0 to 2 year-old infant urine samples were collected, Thyroid gland was palpated and urinary iodine was determined by iodine in urine by As3+-Ce4+catalytic spectrophotometry, salt iodine was determined by direct titration. Results The goiter rates of 8 to 10 year-old students were 1.5 % (3/200), 1.0% (1/100) for the urban area and 2.0% (2/100) for rural area. Median of urinary iodine in 8 to 10 year-old students, infants, women of childbearing age averaged at 237.1 μg/L and 280.1, 234.7,187.6 μg/L respectively, with each being 287.4,245.0,205.5 μg/L in urban area and 278.9,228.5,176.4 μg/L in rural area. Women of childbearing age had a higher percentage of urinary iodine < 50.0 μg/L than students,students had a higher percentage than infants, each being 7.5%(15/200), 4.5%(9/200), 4.0%(4/100). The ration of urinary iodine > 300.0 μg/L was more in infants than in students, that in students was more than that in women of childbearing age, each being 33.0% (33/100), 30.0% (60/200),22.5% (45/200). The median of salt iodine was 27.2 mg/kg. The coverage of iodized salt was 100.0%(400/400). Ninty-seven percent(194/200) and 96.0% (192/200) of qualified iodized salt were consumed in urban area and in rural area. Conclusions The amount of iodine added to salt meets the requirement in the 3 kinds population risk of iodine deficiency disorder. But a higher iodine status has been found out in students and infants. It is reasonable to decrease the present salt iodine content.  相似文献   
89.
OBJECTIVES: To determine the type of electrocardiogram (ECG) interpretation instruction in emergency medicine (EM) residency programs, the use and perceived value of teaching modalities and resources, and the methods used to assess competency of ECG interpretation. METHODS: An interactive survey instrument was posted on the Internet using SurveySuite, Inc., software and e-mailed to program directors (PDs) of all 125 Accreditation Council for Graduate Medical Education-approved U.S. EM residency programs. Responses are reported in total numbers and percentages. RESULTS: Ninety-nine of 125 PDs completed the online survey (response rate, 79.2%). Emergency department instruction (99%), case-based lectures (98%), and didactic lectures (98%) were most commonly used to teach interpretation of ECGs, followed by computer-based instruction (34%) and ECG laboratory (12%). The majority of programs (53%) spent more than eight hours on formal ECG lectures per year, while 11% spent less than three hours. Observation during clinical time (99%), lecture time (76%), and hypothetical cases (57%) were the most common ways to determine competency in reading ECGs, while clinical observation and hypothetical cases were perceived as the most valuable. The most commonly used resource was personal or departmental ECG files (91%), and this had the highest perceived value. The majority of PDs were comfortable with residents' abilities to read ECGs by the third year (96%) and fourth year (91%) of residency. CONCLUSIONS: These data suggest that EM PDs believe that EM residency is adequately preparing graduates to interpret ECGs. This goal is achieved through a variety of methods.  相似文献   
90.
下腔静脉损伤的救治经验:附12例报告   总被引:1,自引:0,他引:1       下载免费PDF全文
目的: 探讨下腔静脉损伤的修复方法。方法:对12例下腔静脉损伤患者临床资料进行回顾性分析。结果:闭合性损伤9例,开放性损伤3例。入院时均伴有休克。均诊断为腹腔内脏损伤,无1例诊断为下腔静脉损伤。12例均手术治疗,直视下修复5例,大网膜填塞后肝实质大块褥式缝合2例,纱布填塞5例。术后并发症7例(58.3%):胆漏1例,隔下脓肿合并反应性右侧胸腔积液2例,创伤性肝囊肿1例,腔静脉血栓形成1例,大出血2例;死亡3例,病死率25.0%。 结论:腔静脉损伤病情凶险,处理困难,病死率高,改良的全肝血流阻断下行纱布填塞止血效果好,抢救成功率高,值得推广。  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