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   43652篇
  免费   2670篇
  国内免费   878篇
耳鼻咽喉   368篇
儿科学   991篇
妇产科学   366篇
基础医学   3538篇
口腔科学   430篇
临床医学   6461篇
内科学   8259篇
皮肤病学   238篇
神经病学   2982篇
特种医学   1161篇
外国民族医学   2篇
外科学   5097篇
综合类   6243篇
现状与发展   3篇
预防医学   2633篇
眼科学   2516篇
药学   4512篇
  27篇
中国医学   1182篇
肿瘤学   191篇
  2024年   58篇
  2023年   696篇
  2022年   1036篇
  2021年   1816篇
  2020年   1653篇
  2019年   1411篇
  2018年   1466篇
  2017年   1354篇
  2016年   1353篇
  2015年   1313篇
  2014年   2853篇
  2013年   3219篇
  2012年   2297篇
  2011年   2591篇
  2010年   1925篇
  2009年   1916篇
  2008年   2038篇
  2007年   1980篇
  2006年   1794篇
  2005年   1469篇
  2004年   1276篇
  2003年   1034篇
  2002年   912篇
  2001年   866篇
  2000年   710篇
  1999年   641篇
  1998年   568篇
  1997年   604篇
  1996年   500篇
  1995年   552篇
  1994年   479篇
  1993年   420篇
  1992年   438篇
  1991年   390篇
  1990年   354篇
  1989年   321篇
  1988年   324篇
  1987年   298篇
  1986年   269篇
  1985年   305篇
  1984年   305篇
  1983年   181篇
  1982年   251篇
  1981年   197篇
  1980年   175篇
  1979年   157篇
  1978年   135篇
  1977年   80篇
  1976年   67篇
  1975年   47篇
排序方式: 共有10000条查询结果,搜索用时 265 毫秒
71.
目的:建立一种更符合临床的筋膜间室综合征动物模型,以便于基础及临床研究。方法:用宽度和犬小腿肌腹长度相当的袖带包绕小腿,然后充气使实验肢体全长受压、缺血。12只犬随机分为两组,I组:袖带充气至40kPa,压迫8h;Ⅱ组:袖带充气至80kPa,压迫8h。结果:动态监测组织压并对神经、肌肉行组织学检查,发现实验动物肢体胫前筋膜间室内组织压远远超过4.0kPa,神经、肌肉发生不可逆变性、坏死。结论:用充气袖带压迫法建立的动物模型是成功的,各项指标均达到筋膜间室综合征的诊断标准。  相似文献   
72.
目的研究推拿治疗老年高血压及对动态血压负荷的影响。方法选择60例轻、中度高血压患者,随机分为推拿治疗组30例,药物对照组组30例。结果推拿治疗组总有效率为83.3%。药物对照组为86.7%;治疗组主要症状疗效前后对比有显著性差异(p〈0.05),治疗组治疗后动态血压负荷值明显降低,较治疗前差异有显著性(p〈0.01,p〈0.05)。结论推拿治疗老年高血压疗效显著,推拿可降低动态血压负荷。  相似文献   
73.
Pressure ulcers are a high-risk, high-volume, and high-cost problem for persons with disabilities. This article describes four tools published in the literature and reports the validity, reliability, strengths, and limitations of each. These tools include the Pressure Ulcer Scale for Healing (PUSH), the Pressure Sore Status Tool (PSST), the Sussman Wound Healing Tool (SWHT), and the Sessing Scale. Rehabilitation nurses should use a consistent framework with accurate quantification to assess, document, and monitor changes in pressure ulcers over time. Such a measurement tool must prove valid for the disabled population in which the tool is used. This will enable healthcare providers to communicate more effectively and evaluate the therapeutic plan of care.  相似文献   
74.
Background  Surgical procedures enhance production of pro- and anti-inflammatory cytokines and angiogenic factors that play a pivotal role in the immunological response to surgical trauma and take part in the pathogenesis of tumor growth and adhesions formation. The purpose of the study was to access the influence of low-pressure CO2 pneumoperitoneum on the inflammatory and angiogenic responses during the postoperative period after laparoscopy. Methods  The study group consisted of 40 patients, operated on due to cholelithiasis using standard-pressure (n = 20) and low-pressure (n = 20) CO2 pneumoperitoneum. Serum concentration of interleukin (IL)-6, IL-8, IL-10, vascular endothelial growth factor (VEGF)-A, and endostatin were measured before and at 6, 24, and 48 h after surgery with commercially available enzyme-linked immunosorbent assay (ELISA). Results  Concentrations of IL-6 increased significantly after the operations in both groups. No differences were observed between the groups in regards to IL-6, IL-8, and IL-10 levels. Concentrations of VEGF-A measured at 6 and 48 h were significantly lower in patients who underwent laparoscopies performed with low-pressure pneumoperitoneum. No significant variations were observed in endostatin serum concentration. Concentrations of the studied parameters were not influenced by duration of surgery or by age, gender, or body mass index (BMI) of the patients. Conclusions  The results obtained in our study do not show any significant differences between studied operative procedures with regards to systemic inflammatory response. Changes in the concentrations of VEGF-A and endostatin observed in the studied population may suggest this technique is more favorable with regards to angiogenesis process intensity, along with all its consequences and implications.  相似文献   
75.
76.
Sutureless bowel anastomosis using Nd:YAG laser   总被引:5,自引:0,他引:5  
Small bowel anastomoses were performed without sutures by using the Nd:YAG laser to produce welded enterotomies. Optimal energy levels for contact and noncontact laser were determined. Anastomoses produced using five target energy levels between 100 and 500 J were examined. Short-term anastomotic strength of these enterotomies was measured 1 min after the welding. Bursting pressure of the laser welded enterotomies was compared to the bursting pressure of traditional two-layer, inverting, interrupted sutured bowel anastomoses. The overall mean bursting pressure of non-contact-welded enterotomies was 50.6 mmHg. Optimal laser settings determined in this initial phase were then used to produce anastomoses in rabbits which are recovered postoperatively for 1 or 2 weeks in order to examine long-term viability and integrity of the anastomoses. All chronic rabbit preparations recovered without complication. The mean bursting pressure was 200 mmHg, not significantly different from that of uncut bowel or two-layer sutured anastomosis.  相似文献   
77.
目的探讨持续正压通气辅助治疗高血压并发睡眠呼吸暂停综合征(SAS)对血压的影响。方法41例高血压并发睡眠呼吸暂停综合征病人,随机分为常规组(21例)和持续正压通气治疗组(20例)均给予常规降压药物治疗4周,治疗在常规治疗基础上加用气道持续正压通气治疗,观察两组治疗前后24 h血压变化。结果治疗组治疗后24 h平均收缩压、舒张压进一步降低,夜间收缩压及舒张压则显著降低(P〈0.01)。结论高血压并发睡眠呼吸暂停综合征病人,在常规应用降压药物同时应用持续正压通气辅助治疗血压下降更理想。  相似文献   
78.
Transcranial Doppler (TCD) is an accepted modality for the evaluation of cerebral blood flow velocities. OBJECTIVES: The purpose of this study was to test the feasibility of bedside TCD measurement in the emergency department (ED) with critically ill, intubated patients. METHODS: A prospective convenience sample of patients presenting to a university hospital over a two-month period underwent TCD evaluation of the middle cerebral artery. Intubated patients with head trauma and any patient requiring tracheal intubation were eligible. A 2-MHz Doppler probe was positioned over the temporal bone to acquire blood flow velocities. An emergency medicine resident and research assistant obtained measurements. Continuous TCD tracings were recorded on a video cassette recorder tape for quality assurance review and data collection. Vital signs and therapeutic interventions were also recorded. Flow velocities were measured in cm/s; the peak Resistance Index (RI) was calculated for each patient. RESULTS: A total of 30 patients were enrolled in the study. Adequate tracings were obtained in 25 patients (83%) without a disruption of resuscitation. Tracings could not be obtained in five patients; they were listed as TCD failures. However, in two of these patients, adequate flow velocity tracings were obtained after resuscitation. Four patients were evaluated during tracheal intubation. One patient was monitored successfully during cardiopulmonary resuscitation. The median time required for data acquisition was 1.9 minutes. The mean highest RI for those who expired was 0.84. For those who survived, the mean highest RI was 0.52. The difference of 0.32 was statistically significant (p = 0.04). CONCLUSIONS: Noninvasive blood flow velocity monitoring of the middle cerebral artery using TCD is feasible in the ED when performed at the bedside on intubated patients with traumatic brain injury and others during tracheal intubation and resuscitation.  相似文献   
79.
Objective This study aims to question the generally accepted cerebrospinal fluid (CSF) bulk flow theory suggesting that the CSF is exclusively absorbed by the arachnoid villi and that the cause of hydrocephalus is a CSF absorption deficit. In addition, this study aims to briefly describe the new hydrodynamic concept of hydrocephalus and the rationale for endoscopic third ventriculostomy (ETV) in communicating hydrocephalus. Critique The bulk flow theory has proven incapable of explaining the pivotal mechanisms behind communicating hydrocephalus. Thus, the theory is unable to explain why the ventricles enlarge, why the CSF pressure remains normal and why some patients improve after ETV. Hydrodynamic concept of hydrocephalus Communicating hydrocephalus is caused by decreased intracranial compliance increasing the systolic pressure transmission into the brain parenchyma. The increased systolic pressure in the brain distends the brain towards the skull and simultaneously compresses the periventricular region of the brain against the ventricles. The final result is the predominant enlargement of the ventricles and narrowing of the subarachnoid space. The ETV reduces the increased systolic pressure in the brain simply by venting ventricular CSF through the stoma. The patent aqueduct in communicating hydrocephalus is too narrow to vent the CSF sufficiently.  相似文献   
80.
BACKGROUND: Moderate hypothermia is one of the effective therapeutic methods for head injury in recent years, there are many mechanisms of moderate hypothermia for brain protection, and its influence on cerebral oxygenation is also one of them. OBJECTIVE: To observe the influence of moderate hypothermia on cerebral oxygenation of animals with acute intracranial hypertension, and further investigate the protective mechanism of moderate hypothermia. DESIGN: A randomized controlled trial. SETTING: Department of Neurosurgery, Renji Hospital affiliated to the Medical College of Shanghai Jiao Tong University. MATERIALS: Twenty healthy little pigs, either male or female, weighing 4.5–5.5 kg, were used. Neurotrend-typed multiparameter monitoring system (Diametrics Company, British); CMA/100 micro-injection pump (Carnegie Company, Sweden). METHODS: The experiment was conducted in the Changzheng Hospital affiliated to the Second Military Medical University of Chinese PLA in November, 2001. The pigs were randomized into two groups: the normothermia group (control group, n =10) and moderate hypothermia group (n =10). ① Bilateral femoral arteries were separated, one was connected to pressometer for monitoring mean arterial pressure (MEP), and the other for analysis of blood gases [including peripheral blood pH value, arterial partial pressure of carbon dioxide (PaCO2), arterial partial pressure of carbon dioxide (PaCO2), HCO3–]. ② Rectal temperature was monitored with mercurial thermometer. ③ Intracranial pressure was monitored using Camino optic ICP probe placed in the subdural space. ④ Neurotrend multiparameter monitoring sensor was inserted into the white matter for about 4 cm to determine cerebral perfusion pressure (CPP, CPP=MAP(ICP), brain tissue partial oxygen pressure (PO2), partial pressure of carbon dioxide (PCO2), HCO3– and brain temperature. The rectal temperature of animals in the moderate hypothermia group was lowered to 34 ℃ using ice bags, and the body temperature was maintained at 33–35 ℃ for 2 hours. The changes of the parameters were observed continuously, and the pigs in the normothermia group were not treated with cooling. MAIN OUTCOME MEASURES: ① MAP, ICP, rectal temperature, CCP; Indexes of cerebral oxygenation detected with Neurotrend-typed multiparameter monitoring system; ② Results of blood gases analysis in the moderate hypothermia group. RESULTS: All the 20 pigs were involved in the analysis of results. ① MAP, ICP, rectal temperature, CCP and indexes of cerebral oxygenation: In the moderate hypothermia group, the ICP after cooling was obviously lower than that before cooling [(3.31±1.19), (5.33±0.95) kPa, P < 0.05], CCP was higher, brain tissue PCO2 [(12.03±1.73), (10.59±2.01) kPa, P < 0.05], and brain tissue pH value was higher [(7.03±1.63), (9.40±1.30) kPa, P < 0.05], whereas the brain temperature was decreased as compared with that before cooling [(34.9±0.3), (37.2±0.2) ℃, P < 0.05]. ② Results of blood gases analysis in the moderate hypothermia group: There were no significant differences in the parameters of peripheral arterial blood gases analysis before and after cooling in the moderate hypothermia group (P > 0.05) CONCLUSION: Moderate hypothermia will not impair the cerebral oxygenation, and it can reduce brain tissue CO2 and decrease brain tissue acidosis.  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