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   1586篇
  免费   166篇
  国内免费   30篇
耳鼻咽喉   1篇
儿科学   77篇
妇产科学   27篇
基础医学   176篇
口腔科学   80篇
临床医学   232篇
内科学   283篇
皮肤病学   18篇
神经病学   70篇
特种医学   272篇
外科学   137篇
综合类   48篇
一般理论   2篇
预防医学   188篇
眼科学   23篇
药学   68篇
肿瘤学   80篇
  2021年   17篇
  2020年   8篇
  2019年   11篇
  2018年   25篇
  2017年   12篇
  2016年   23篇
  2015年   27篇
  2014年   33篇
  2013年   42篇
  2012年   39篇
  2011年   48篇
  2010年   53篇
  2009年   39篇
  2008年   42篇
  2007年   61篇
  2006年   55篇
  2005年   49篇
  2004年   42篇
  2003年   56篇
  2002年   31篇
  2001年   36篇
  2000年   38篇
  1999年   42篇
  1998年   70篇
  1997年   80篇
  1996年   90篇
  1995年   59篇
  1994年   46篇
  1993年   53篇
  1992年   37篇
  1991年   32篇
  1990年   32篇
  1989年   51篇
  1988年   57篇
  1987年   43篇
  1986年   39篇
  1985年   41篇
  1984年   15篇
  1983年   13篇
  1982年   18篇
  1981年   17篇
  1980年   14篇
  1979年   16篇
  1978年   8篇
  1977年   14篇
  1976年   15篇
  1975年   8篇
  1969年   10篇
  1967年   6篇
  1966年   6篇
排序方式: 共有1782条查询结果,搜索用时 0 毫秒
131.
BACKGROUND: Patients presenting for cardiac surgery are often treated with angiotensin converting enzyme inhibitors (ACEIs), either for heart failure or hypertension. Control of systemic vascular resistance (SVR) during surgery can be difficult in such patients. Angiotensin II has been available as an unlicensed vasoconstrictor, but there is concern about renal damage and its use. AIM: This study compared a standard vasoconstrictor with angiotensin II and examined the effect on renal function after cardiac surgery. METHOD: Twenty consecutive, consenting patients scheduled for cardiac surgery that had been taking ACEIs for at least 6 months, were randomly assigned to receive either phenylephrine or angiotensin II for the control of SVR during and for 24 h after cardiac surgery. A pulmonary artery catheter was used to guide therapy. Creatinine clearance was measured before, 24 and 48 h after surgery. RESULTS: Low SVR and blood pressure requiring intervention was seen in all patients, particularly during cardiopulmonary bypass. One patient in the control group failed to respond to P, but responded normally to angiotensin II. Neither drug caused renal impairment. CONCLUSION: Angiotensin II is a safe alternative to phenylephrine in patients on ACEIs and should be considered in patients who fail to respond to conventional vasoconstrictors.  相似文献   
132.
OBJECTIVE: To develop and evaluate service user, carer and community involvement in health and social care education. BACKGROUND: Despite the high policy profile of involvement issues, there appear to be no published accounts of schemes that have used a systematic whole-faculty approach to community engagement in health and social care higher education. FOCUS OF THIS PAPER: The set up and early development of a faculty-wide community engagement project. SETTING AND PARTICIPANTS: Staff from the faculty of health in one University, local service users and carers and community group project workers and local National Health Service (NHS) and public sector staff. DESIGN: Participatory action research including document review, field notes, questionnaires and interviews. ANALYSIS: Thematic analysis. The emerging themes were tested by seeking disconfirming data, and through verification with stake-holders. RESULTS: Prior to the study, there were examples of community engagement in the participating faculty, but they occurred in specific departments, and scored low on the 'ladder of involvement'. Some previous attempts at engagement were perceived to have failed, resulting in resistance from staff and the community. Despite this, an advisory group was successfully formed, and project framing and development evolved with all stake-holders over the subsequent year. The four themes identified in this phase were: building accessibility; being 'proper' service users/carers;moving from suspicion to trust: mutually respectful partnerships as a basis for sustainable change; and responses to challenge and emergence. CONCLUSIONS: Successful and sustainable engagement requires authenticity. Many problems and solutions arising from authentic engagement are emergent, and potentially challenging to organizations.  相似文献   
133.
An 11-year-old girl presented with pyrexia, severe mitral regurgitation, and cardiac failure. The child''s condition deteriorated necessitating an emergency life-saving valve replacement. Although the revised Jones''s criteria were not fulfilled, histology confirmed acute rheumatic carditis.  相似文献   
134.
135.
Sartoris  DJ; Clopton  P; Nemcek  A; Dowd  C; Resnick  D 《Radiology》1986,160(2):479-483
The radiographic patterns of vertebral-body collapse and/or endplate deformity were examined in 99 autopsy specimens of the thoracolumbar spine with benign and malignant disease. Angling of endplates was found to be highly predictive of underlying malignancy, whereas concavity was more suggestive of benign disease, for both individual vertebral bodies and intact spines (P less than .001). Diffuse-concave, diffuse-angled, and focal-angled patterns were more useful (P less than .001) than the focal-concave pattern (P = .07) in distinguishing between benign and malignant disease for superior endplates, whereas all were equally useful (P less than .025) in inferior endplates. Condition of the adjacent disks, location within the spine, and position of the apex of collapse were not predictive. Although these results and subsequent blinded testing suggest that reliable distinction between benign and malignant vertebral collapse is possible, extrapolation to clinical practice may be inappropriate because of population bias in the study and differences in radiographic quality between autopsy specimens and live subjects.  相似文献   
136.
Pathria  M; Sartoris  DJ; Resnick  D 《Radiology》1987,164(1):227-230
Sensitivity and specificity of lumbar spine radiography in the assessment of facet joint osteoarthritis were evaluated, with computed tomography (CT) as the standard. Two independent radiologists used a four-point scale to blindly grade facet joint osteoarthritis on oblique radiographs and transaxial CT scans obtained within an 8-month period in 50 consecutive patients with pain in the lower back. The L-3 to L-4, L-4 to L-5, and L-5 to S-1 facet joints were evaluated, and 68% appeared abnormal on CT scans, with 28% exhibiting moderate or severe disease. Interobserver agreement was high for conventional radiography (perfect agreement in 57% and agreement to within one grade in 39%) and still higher for CT (perfect in 63% and to within one grade in 35%). Receiver operating characteristic curve analysis indicated that oblique radiography was most accurate (55% sensitivity, 69% specificity) in distinguishing the presence from the absence of disease; in distinguishing absent or mild from moderate or severe disease, the specificity of oblique radiography was higher, at 94%, but its sensitivity was much lower, at 23%. Conventional radiography is a useful technique in screening for facet joint osteoarthritis but is insensitive compared with CT.  相似文献   
137.
T J McKeown 《AANA journal》1991,59(4):365-372
A 27-year-old white male was scheduled for a mediastinoscopy of an anterior mediastinal mass. The patient was induced with thiopental and succinylcholine, in anticipation of possible difficulty managing the airway. There was no distortion of the airway, and he was easily intubated with a No. 8.5 anode tube and given 20 mg of atracurium. The extent of tumor growth was greater than expected and, as a result, biopsies of the neck were taken without the need for mediastinoscopy. The atracurium was reversed with atropine and edrophonium. Although respirations were being assisted, the SaO2 decreased significantly, and end-tidal CO2 was greatly increased. When the drapes were removed, the patient was found to be cyanotic, with vein distention in the neck and upper extremities. All anesthetic agents were discontinued, the patient was hyperventilated with 100% oxygen, 100 mg of lidocaine was given for coughing and breath-holding, and the patient was placed in the reverse Trendelenburg position. The SaO2 then increased, and the end-tidal CO2 decreased. Respirations were spontaneous, and the patient could be extubated. The probable cause of this episode was obstruction of the superior vena cava by the anterior mediastinal mass. When the muscle relaxant was reversed, the increase in intrathoracic pressure caused the mass to compress the superior vena cava. The compression was released by placing the patient in a reverse Trendelenburg position, which caused the mass to shift. In addition to superior vena cava compression, other complications of anterior mediastinal masses include airway obstruction, distortion of anatomy, impaired cerebral circulation and myasthenic syndrome.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
138.
The ability of graduated compression elastic stockings to prevent hypotension during elective epidural caesarean section was evaluated. Twenty women were randomly assigned to two groups of ten, one group being fitted with the stockings. The incidence and degree of hypotension were the same in both groups. Graduated compression elastic stockings are of no benefit in reducing the incidence of maternal hypotension during caesarean section.  相似文献   
139.
Medical schools put little emphasis upon education on public health, even though public health has played an important role in this century. One way to harness its benefit in order to improve global health in the 21st century is to globally share lectures on public health through the Internet. We have developed the Supercourse comprising of web-based learning modules on epidemiology in a standardized format with the size of each web page less than 10 kilobytes. A cross-sectional observational study was conducted to investigate the association of the perception of the access speed to Web-based lectures by teachers with their perception of lecture quality. There were 223 teachers who rated the lectures: 72% were from North America or Western Europe, 40% had taught epidemiology, and 14% reported that the speed of access was slow. Odds ratio of above-average rating among those who reported that the speed of access was fast relative to those who reported that the speed of access was slow was 4.25 (2.03-8.91; P = 0.001). The odds ratios were similar and significant after taking into account several other factors, including the variation of rating across lectures, region, and experiences in teaching epidemiology. The results indicate that the perception of the quality of Web-based lectures is related to the speed of access to a web page. The speed of access may be as important, if not more important, as the content itself. This suggests that, to share educational materials on the Web globally for teachers, one must consider not only the content, but also how people at local sites gain access to the Internet.  相似文献   
140.
Gelfand  DW; Chen  YM; Ott  DJ 《Radiology》1987,164(2):333-337
A systems approach was employed to improve results of the single-contrast barium enema examination for detection of colonic polyps. Improvements were made in each of the following areas: radiographic-fluoroscopic equipment, fluoroscopic-television images, screen-film combinations, barium suspensions, examination techniques, imaging sequences, and quality controls. Radiologic-endoscopic correlation was undertaken for 137 colonic polyps seen endoscopically in 91 patients. The average age of the patients was 69 years. The sensitivity of the single-contrast examination for detection of all polyps was 80%. Polyps 5-9 mm in size were detected with 66% sensitivity, while 94% of polyps 10 mm or larger were detected. The results indicate that the sensitivity of a suitably performed single-contrast barium enema examination may approach that of the double-contrast study for the detection of colonic polyps, even in an elderly and infirm patient population.  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