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   1313篇
  免费   70篇
  国内免费   6篇
耳鼻咽喉   6篇
儿科学   65篇
妇产科学   31篇
基础医学   119篇
口腔科学   12篇
临床医学   138篇
内科学   444篇
皮肤病学   70篇
神经病学   74篇
特种医学   20篇
外科学   265篇
综合类   12篇
预防医学   27篇
眼科学   34篇
药学   23篇
中国医学   3篇
肿瘤学   46篇
  2023年   9篇
  2022年   14篇
  2021年   32篇
  2020年   17篇
  2019年   32篇
  2018年   32篇
  2017年   17篇
  2016年   25篇
  2015年   24篇
  2014年   37篇
  2013年   38篇
  2012年   75篇
  2011年   79篇
  2010年   50篇
  2009年   58篇
  2008年   73篇
  2007年   74篇
  2006年   75篇
  2005年   74篇
  2004年   67篇
  2003年   57篇
  2002年   42篇
  2001年   29篇
  2000年   36篇
  1999年   32篇
  1998年   20篇
  1997年   14篇
  1996年   5篇
  1995年   10篇
  1994年   6篇
  1992年   22篇
  1991年   23篇
  1990年   26篇
  1989年   19篇
  1988年   14篇
  1987年   14篇
  1986年   16篇
  1985年   6篇
  1984年   12篇
  1983年   10篇
  1982年   5篇
  1980年   6篇
  1979年   8篇
  1978年   4篇
  1977年   4篇
  1974年   8篇
  1972年   8篇
  1966年   3篇
  1964年   3篇
  1948年   4篇
排序方式: 共有1389条查询结果,搜索用时 15 毫秒
51.
Serum prolactin levels were measured in maternal and fetal sera immediately post delivery in 20 cases of premature rupture of the membranes and in 20 controls. Fetal serum prolactin levels were 781 +/- 265 ng/ml in cases of PRM and 737 +/- 314 ng/ml in controls. Maternal serum prolactin levels were 504 +/- 264 ng/ml in cases of PRM and 731 +/- 361 ng/ml in controls. This difference is statistically significant (t = 1.81, p less than 0.05). A probable role of prolactin in maintaining fetal membrane integrity and the probable effect of the difference in maternal serum prolactin concentration in the two groups on the membranes' viscoelastic properties is discussed.  相似文献   
52.
The scurvy shows an inflammatory disease and gingival bleeding. Nevertheless, in an animal model for guinea pigs, described by Den Hartog Jager in 1985, scurvy was associated with a motor neuron disease with demyelinization of the pyramidal tract, provoking neurogenic atrophy of muscles. Aiming at searching the protective role of vitamin C in nervous system, a pharmacological, morphological and behavioral study was conducted. Three experimental groups were used: A100, animals receiving 100 mg/ vitamin C/ day; A5.0, animals receiving 5.0 mg/vitamin C/ day; and A0, animals without vitamin C. We analyzed the weight gain, muscular diameter and behavioral tests. In all tests examined, we found significant differences between the supplemented groups in comparison with scorbutic group (p<0.05). Thereafter, the animals were killed for histopathology of gastrocnemius muscle, spinal cord and tooth tissues. In addition, a morphometric study of periodontal thickness and alpha-motor neuron cell body diameter were done. The vitamin C-diet free regimen seemed to induce a disruption in spinal cord morphology, involving the lower motor neuron, as confirmed by a significant reduction in neuron perycaria diameter and muscular atrophy, complicated by increased nutritional deficit.  相似文献   
53.
54.
BACKGROUND: Ischemic mitral regurgitation is known to be associated with poor long-term outcome after coronary artery bypass grafting; however, our ability to alter that outcome with intervention on the valve is unclear. The decision to address the valve is most challenging for patients with only moderate mitral regurgitation, particularly with the popularization of off-pump surgery. We therefore reviewed early and late outcomes of patients undergoing revascularization with or without mitral valve surgery. METHODS: Patients with moderate mitral regurgitation undergoing revascularization with and without mitral surgery between January 1991 and September 1996 were identified retrospectively. Operative notes were reviewed and patients with structural valve disease excluded. Perioperative events and late outcomes as determined by telephone contact and search of the social security death index (survival data 97% complete) were compared. RESULTS: One hundred seventy-six patients with moderate mitral regurgitation underwent revascularization alone (n = 142) or with mitral repair or replacement (n = 34). Those undergoing revascularization alone had a higher serum creatinine, somewhat less mitral regurgitation, and lower New York Heart Association functional class preoperatively. Operative mortality was greater with valve surgery (21% vs 9%, p = 0.047). Actuarial survival of both groups at 5 years was similar (52% vs 58%, p = NS); however, when stratified by preoperative functional class, those with more advanced heart failure preoperatively had superior late survival if their mitral valve was intervened upon. CONCLUSIONS: The late survival of patients with ischemic mitral regurgitation undergoing coronary revascularization remains poor; however, intervention on the mitral valve appears to benefit those with symptomatic heart failure.  相似文献   
55.
Respiratory difficulties are not uncommon during epileptic activity in all age groups. Laryngospasm, as an isolated manifestation of epileptic disorder, is a rare phenomenon described previously in only two patients. We report our experience with five children in whom nocturnal laryngospasm was the only clinical manifestation of their epileptic disorder. All children underwent extensive workup and the diagnosis was made by sleep-deprived electroencephalography (two cases) and sleep study (three cases). All patients were treated with carbamezapine with prompt resolution of their laryngospasm.  相似文献   
56.
AIM: To investigate whether hepatitis B vaccination has increased the number of cases of unexplained neonatal fever. METHOD: The files of all infants born from 1 January 1991 to 31 December 1992, in whom a diagnosis of "injected antibiotic" or "disease of temperature regulation" was recorded, were reviewed. Those who had unexplained fever of 38 degrees C or higher during the first three days of life were divided into two groups: infants who did not receive the hepatitis B vaccine (1991) and infants who did (1992). RESULTS: In 1992 the incidence of unexplained fever in hepatitis B vaccinated neonates was significantly higher than in the 1991 group of pre-vaccination neonates (35 out of 5819 (0.6%) vs 14 out of 5010 neonates (0.28%) respectively, p=0.013). CONCLUSIONS: The increase in the number of cases of unexplained neonatal fever seems to be associated with the introduction of routine hepatitis B vaccination on the first day of life. The possibility that an excess number of neonates will undergo unnecessary procedures and treatment to diagnose unexplained fever justifies planning a controlled study to determine whether these preliminary findings point to a significant problem.  相似文献   
57.
Four patients with end-stage renal failure on intermittent hemodialysis in whom rhabdomyolysis developed after major surgery are described. This possibly underdiagnosed complication was manifested by extreme hyperphosphatemia, hypocalcemia, and elevated creatine phosphokinase levels. Serum myoglobin levels further supported the diagnosis. The metabolic abnormalities reached a peak on the fourth postoperative day. The possible precipitating factors included opiates used for anesthesia and postoperative pain control, anesthetic agents, and surgical position. The preferred treatment option is increasing dialysis to control hyperphosphatemia and hypocalcemia.  相似文献   
58.
59.
60.
OBJECTIVES/HYPOTHESIS: The objective was to investigate the functional and histological properties of surgical procedures using a new carbon dioxide (CO2) laser fiber. STUDY DESIGN: In vitro and in vivo animal models. METHODS: In vitro experiments using porcine true vocal cord and arytenoid cartilage were designed to study the histological effects of using a photonic band-gap fiber assembly for CO2 laser energy delivery. Continuous and pulsed-wave settings at different wattages were tested. In vivo endoscopic surgery on canine larynges and buccal mucosa were performed to examine functional and short-term healing when performing photonic band-gap fiber assembly-assisted laser surgery. RESULTS: In vitro experiments showed consistent cutting with the photonic band-gap fiber assembly using either straight or 90 degrees bent-tip fibers. The surrounding tissue in these experiments showed little collateral thermal damage with the average range of thermal width from 14.1 to 18.8 microm in vocal cords and from 5.2 to 10.5 microm in cartilage. Similarly, thermal depth ranged from 28.0 to 350.0 microm in vocal cords and from 269.7 to 739.6 microm in cartilage. In vivo experiments demonstrated ease in maneuvering and flexibility for cutting. There was minimal blood loss, smoke plume, or carbonaceous debris. There were no postprocedural complications. Normal oral intake was noted on postprocedural day 1. There was no evidence of stridor or respiratory distress. Seven days after the procedure, re-epithelialization was complete in the buccal incisions and nearly completed in the laryngeal incisions. CONCLUSION: The photonic band-gap fiber assembly produced reliable results in cutting with functional characteristics representing an improvement over current technology. The device shows promise as an effective tool for minimally invasive procedures that are amenable to use of the CO2 laser.  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