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   41979篇
  免费   2159篇
  国内免费   260篇
耳鼻咽喉   449篇
儿科学   895篇
妇产科学   623篇
基础医学   5269篇
口腔科学   1031篇
临床医学   2683篇
内科学   11132篇
皮肤病学   769篇
神经病学   2853篇
特种医学   1441篇
外科学   7894篇
综合类   206篇
一般理论   3篇
预防医学   1254篇
眼科学   485篇
药学   2758篇
中国医学   125篇
肿瘤学   4528篇
  2023年   274篇
  2022年   506篇
  2021年   874篇
  2020年   479篇
  2019年   660篇
  2018年   806篇
  2017年   692篇
  2016年   770篇
  2015年   810篇
  2014年   1078篇
  2013年   1287篇
  2012年   2026篇
  2011年   2150篇
  2010年   1244篇
  2009年   1079篇
  2008年   1962篇
  2007年   2145篇
  2006年   2153篇
  2005年   2243篇
  2004年   2137篇
  2003年   2075篇
  2002年   1922篇
  2001年   1289篇
  2000年   1398篇
  1999年   1228篇
  1998年   553篇
  1997年   418篇
  1996年   405篇
  1995年   354篇
  1994年   294篇
  1993年   319篇
  1992年   811篇
  1991年   737篇
  1990年   713篇
  1989年   764篇
  1988年   679篇
  1987年   617篇
  1986年   561篇
  1985年   539篇
  1984年   359篇
  1983年   296篇
  1979年   265篇
  1978年   201篇
  1977年   172篇
  1974年   159篇
  1973年   170篇
  1972年   172篇
  1971年   158篇
  1970年   157篇
  1969年   149篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
92.
During the span of five years from October, 1987 to December, 1992, we have operated on six cases of carotid body tumours. Total excision was performed in five patients; one patient had 90% of the tumour excised. All patients had pre-operative balloon occlusion test; only one patient showed electroencephalographic changes. Three patients required intra-operative intraluminal shunts for various reasons. Microvascular Doppler flowmetery confirmed patency and correct placement of the shunt. Elective use of the intraluminal shunt is very useful for safe excision of carotid body tumours. Microneurosurgical techniques were used for all patients. There were no cerebrovascular sequelae and 25% of patients experienced cranial nerve injury. Average follow up was three years and none of the total excision patients have had recurrence of the tumours.  相似文献   
93.
Background: Propofol and fentanyl infusion rates should be varied according to the patient's responsiveness to stimulation to maintain satisfactory anesthetic and operative conditions. However, somatic and autonomic responses to various noxious stimuli have not been investigated systematically for intravenous propofol and fentanyl anesthesia.

Methods: Propofol and fentanyl were administered via computer-assisted continuous infusion to provide stable concentrations and to allow equilibration between plasma-blood and effect-site concentrations. The propofol concentrations needed to suppress eye opening to verbal command and motor responses after 50-Hz electric tetanic stimulation, laryngoscopy, tracheal intubation, and skin incision in 50% or 95% of patients (Cp50 and Cp95) were determined at fentanyl concentrations of 0.0, 1.0, 2.0, 3.0, and 4.0 ng/ml in 133 patients undergoing lower abdominal surgery. The ability of propofol with fentanyl to suppress hemodynamic reactions in response to various noxious stimuli also was evaluated by measuring arterial blood pressure and heart rate before and after stimulation.

Results: The various Cp50 values for propofol alone (no fentanyl) for the various stimuli increased in the following order: Cp sub 50loss of consciousness, 4.4 micro gram/ml (range, 3.8-5.0); Cp50tetanus, 9.3 micro gram/ml (range, 8.3-10.4); Cp50laryngoscopy, 9.8 micro gram/ml (range, 8.9-10.8); Cp50skin incision, 10.0 micro gram/ml (range, 8.1-12.2); and Cp50intubation, 17.4 micro gram/ml (range, 15.1-20.1; 95% confidence interval). The reduction of Cp50loss of consciousness, with fentanyl was minimal; 11% at 1 ng/ml of fentanyl and 17% at 3 ng/ml of fentanyl. A plasma fentanyl concentration of 1 ng/ml (3 ng/ml) resulted in a 31-34% (50-55%) reduction of the propofol Cp50 s for tetanus, laryngoscopy, intubation, and skin incision. Propofol alone depresses prestimulation blood pressure but had no influence on the magnitude blood pressure or heart rate increase to stimulation. Propofol used with fentanyl attenuated the systolic blood pressure increases to various noxious stimuli in a dose-dependent fashion.  相似文献   

94.
Development and evaluation of a presurgical preparation program   总被引:2,自引:1,他引:1  
Three presurgical preparation programs were developed and evaluated in an Australian hospital utilizing an additive component design. The component basic to all three preparation programs was modeling. This technique was compared with the additional components of teaching child coping skills and parent coping skills via videotape. Subjects were 28 children between the ages of 4 and 13 years who were scheduled for elective surgery. Anxiety of both the children and parents was assessed by self-report and behavior observation. Results indicated that there was no further anxiety reduction by the addition of child and parent coping skills. Results are discussed in terms of the viability of teaching coping skills via videotape particularly to parents. Methodological difficulties associated with research in this area are examined.  相似文献   
95.
BACKGROUND: Cytomegalovirus (CMV) diseases commonly occur in allograft recipients in the early post-transplant period. However, factors responsible for the high incidence of CMV diseases during this period are not yet fully defined. METHODS: Wistar-Furth (WF; RT-1(u)) rats were inoculated with 10(4) plaque-forming units (PFU) of rat CMV (RCMV) intraperitoneally, and then transplanted with allogeneic lungs from Dark Agouti (DA; RT-1avl) rats or stimulated with 10(7) mitomycin C-treated spleen cells from DA rats by daily sub-cutaneous injections for 2 weeks. No immunosuppressive agent was used. Naive WF rats and WF rats grafted with syngeneic lungs or cells were used as controls. The level of RCMV replication in rats was assessed by infectious virus titers in tissues. RESULTS: The virus titers in salivary glands of allogeneic and syngeneic lung graft recipients were significantly higher than in naive WF rats. The level of RCMV replication in rats stimulated with allogeneic spleen cells was significantly higher than in the syngeneic recipient rats: virus titers in the salivary gland of allogeneic and syngeneic recipients reached 4.61 +/- 0.33 and 4.00 +/- 0.37 log(10) PFU/g tissue, respectively, at 14 days post-infection (p = 0.015). The augmented viral replication in allogeneic recipients was confirmed by an increase in the number of RCMV antigen-positive macrophages present in tissue sections of the salivary gland. CONCLUSIONS: Acute lung allograft rejection and allogeneic spleen cell stimulation enhance CMV replication in the salivary gland of rats. Various responses to allogeneic antigens occurring in the process of acute allograft rejection could be risk factors for post-transplant CMV replication and infection.  相似文献   
96.
OBJECTIVE: Continuous retrograde cerebral perfusion during aortic arch surgery is associated with cerebral edema. In this report, we describe the clinical use of a new type of intermittent retrograde cerebral perfusion. SUBJECTS AND METHODS: Fourteen patients with a Stanford type A dissection were included in this study. With the usual method of retrograde cerebral perfusion, about 2,500 mL venous blood is drained from bicaval cannulae into a hard-shell reservoir, and oxygenated blood is perfused through the superior vena caval cannula. The flow rate is 300 mL/min. After about 15 min, retrograde perfusion is discontinued, and drainage from the bicaval cannulae is restarted. When a bloodless field is necessary, perfusion also is discontinued. RESULTS: Two to seven cycles of intermittent retrograde cerebral perfusion were administered (average, 3.1+/-0.4, mean+/-SD). The total retrograde perfusion time was 36.0+/-1.9 min which was equivalent to 74.8% of the circulatory arrest time. No patient developed edema of the upper body. The time to wake-up was 3 to 14 h (average, 6.5+/-1.0 h). No patient suffered any neurologic complications even though the time of circulatory arrest was greater than 60 min in four cases. Head magnetic resonance imaging or computed tomography was performed in 12 cases, and no evidence of hypoxic brain injury was detected. CONCLUSIONS: Our clinical experience using a moderate amount of intermittent retrograde cerebral perfusion is superior to continuous retrograde cerebral perfusion for protecting the brain during aortic arch surgery.  相似文献   
97.
Intraosseous ganglia of the glenoid are rare, and their etiology is unknown. This report describes a case of an intraosseous ganglion about to cause fracture of the glenoid. The patient was a 61-year-old woman with a painful left shoulder with a limited range of motion. Her symptoms did not improve after non-operative treatment. Arthroscopic examination showed a cartilage defect and erosion in the posteroinferior portion of the glenoid, behind which computed tomography (CT) showed a cystic lesion of the glenoid. There was no communication between the cyst and the joint space. The patient was treated by curettage and an autogenous cancellous bone graft from the iliac crest. Two years after the operation, the patient was almost free from pain, and CT showed good integration of the bone graft.  相似文献   
98.
BACKGROUND: The Functional Assessment of Cancer Therapy-Lung (FACT-L) questionnaire, which consists of a core questionnaire (the General Measure of FACT [FACT-G]) and a 9-item Additional Concerns comprised of a 7-item Lung Cancer Subscale (LCS), was developed in an English-speaking culture. The validation of the Japanese FACT-G was reported previously, and this report describes the cross-cultural validation of the LCS. METHODS: The Japanese version of the LCS was developed through an iterative forward-backward translation sequence used throughout the FACT Multilingual Translation Project. In evaluating psychometric performance, its construct validity was investigated with Cronbach's alpha coefficient and factor analysis. Clinical validities of a known-groups comparison and longitudinal validity were also investigated. RESULTS: The FACT-L was administered twice to 180 patients with lung cancer within 2 weeks. The Japanese LCS had borderline values for Cronbachs alpha coefficients (0.62-0.67). Factor analysis indicated that the LCS had the three dimensions of respiratory symptoms, appetite plus body weight, and clear thinking. For clinical validity, a known-groups comparison showed that the LCS could differentiate patients according to truth disclosure, as Japanese doctors sometimes do not fully inform terminally ill patients. However, responsiveness was not proved when performance status was used as an anchor, probably owing to the short interval between the administration of the two measures. CONCLUSION: The Japanese version of the LCS asked questions about multiple symptoms of patients with lung cancer, as did the original English LCS. The longitudinal clinical validity of the Japanese version should be investigated in future clinical trials.  相似文献   
99.
100.
Repeated injections of 45 ng/kg of maitotoxin into the peritoneal cavities of male ICR mice resulted in marked atrophy of lymphoid tissues, a reduction of lymphocytes in the circulating blood, reduced immunoglobulin M in serum, and an increase of calcium content in the adrenal glands. A single injection of 200 ng/kg of maitotoxin induced a marked increase in total calcium content of the adrenal glands as well as in plasma cortisol concentration (about seven times control) within 1 hr. In contrast, mice pretreated with CoCl2, a calcium channel inhibitor, and/or adrenalectomized mice, showed no discernible changes in the lymphoid tissues after repeated injections of maitotoxin. It is thus suggested that maitotoxin first stimulates calcium influx in the adrenal glands, which then causes the release of cortisol into the blood. The excess amount of cortisol in serum produces acute involution of the thymus and other lymphoid tissues.  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