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   7830篇
  免费   715篇
  国内免费   48篇
耳鼻咽喉   63篇
儿科学   294篇
妇产科学   265篇
基础医学   888篇
口腔科学   161篇
临床医学   825篇
内科学   1864篇
皮肤病学   147篇
神经病学   871篇
特种医学   346篇
外国民族医学   1篇
外科学   1130篇
综合类   267篇
一般理论   3篇
预防医学   588篇
眼科学   66篇
药学   385篇
中国医学   1篇
肿瘤学   428篇
  2021年   78篇
  2018年   84篇
  2016年   74篇
  2015年   105篇
  2014年   125篇
  2013年   182篇
  2012年   270篇
  2011年   286篇
  2010年   164篇
  2009年   150篇
  2008年   280篇
  2007年   312篇
  2006年   263篇
  2005年   255篇
  2004年   272篇
  2003年   304篇
  2002年   272篇
  2001年   249篇
  2000年   288篇
  1999年   231篇
  1998年   123篇
  1997年   106篇
  1996年   117篇
  1995年   84篇
  1994年   90篇
  1993年   99篇
  1992年   218篇
  1991年   234篇
  1990年   209篇
  1989年   205篇
  1988年   237篇
  1987年   219篇
  1986年   214篇
  1985年   184篇
  1984年   181篇
  1983年   151篇
  1982年   99篇
  1981年   94篇
  1980年   81篇
  1979年   136篇
  1978年   82篇
  1977年   89篇
  1976年   86篇
  1975年   68篇
  1974年   96篇
  1973年   91篇
  1972年   87篇
  1971年   77篇
  1970年   71篇
  1969年   73篇
排序方式: 共有8593条查询结果,搜索用时 15 毫秒
991.
992.
A prospective, randomized trial was instituted to determine whether blood cardioplegia (BC) could reduce the morbidity and mortality for patients undergoing urgent coronary bypass for unstable angina. One hundred forty patients who came to the hospital with prolonged angina at rest and who required urgent revascularization because their symptoms were resistant to medical therapy were randomized to receive BC (n = 70) or crystalloid cardioplegia (CC) (n = 70). The operative mortality rate was 2.8%, the incidence of myocardial infarction was 8.6%, the incidence of low output syndrome was 18% and morbidity (myocardial infraction or low output syndrome) was 23%. Patients who received BC had a significantly lower mortality rate (BC, 0%; CC, 5%; p less than 0.05) and incidence of myocardial infarction (BC, 4%; CC, 13.5%; p less than 0.05) or low output syndrome (BC, 10%; CC, 19%; p less than 0.05). The highest postoperative CK-MB level was less after BC (BC, 31 +/- 17 U/L; CC, 56 +/- 13 U/L; p less than 0.05). Preoperative predictors of postoperative morbidity in addition to the type of cardioplegia included the response to medical therapy, persistent ischemic electrocardiographic changes, left ventricular ejection fraction, and age. A multivariate analysis identified the type of cardioplegic protection (p = 0.008) and age (p = 0.05) as significant independent predictors of postoperative morbidity. BC reduced the risk of urgent revascularization for unstable angina.  相似文献   
993.
Benign mesenchymoma is a tumor composed of two or more benign mesenchymal elements in addition to fibrous connective tissue. A case of benign mesenchymoma of the lip in a 38-year-old man is presented, and the literature is reviewed.  相似文献   
994.
995.
The effect of the ouabain-quinidine interaction was examined in 10 conscious dogs. Left ventricular (LV) pressure, LV dP/dt, LV diameter and left atrial (LA) diameter were measured with high-fidelity micromanometers and sonomicrometer crystals. Ouabain, 0.025 mg/kg, significantly (p less than 0.05) increased LV dP/dt, LV and LA fractional shortening and LV and LA velocity of circumferential fiber shortening (Vcf). In a separate experiment, quinidine was administered as a bolus dose, 3.85 mg/kg, followed by an infusion, 0.28 mg/kg/min. This resulted in steady-state quinidine concentrations that produced no change in wall motion or hemodynamics. When ouabain was given 1 hour into the quinidine infusion, only LV dP/dt increased significantly (p less than 0.05). Ouabain alone increased LV dP/dt 26.4 +/- 3.5%, whereas ouabain during the quinidine infusion increased it by 9.5 +/- 2.3%. Similar differences were seen in the responses to ouabain in the absence and presence of quinidine: LV Vcf, 22.4 +/- 4.9% vs 6.0 +/- 2.1%, LV fractional shortening, 23.1 +/- 4.6% vs 5.8 +/- 2.1%, LA Vcf, 22.7 +/- 5.9 vs 4.6 +/- 2.0% and LA fractional shortening, 21.8 +/- 7% vs 7.8 +/- 3.3%. Thus, in the presence of quinidine the increase in intropy usually seen with ouabain was markedly attenuated. These data suggest that the quinidine-induced increase in digoxin serum concentrations is accompanied by a decrease in the contractile response of the heart to digoxin.  相似文献   
996.
Human T-cell lymphotropic virus I (HTLV-I)-induced adult T-cell leukemia (ATL) cells constitutively express interleukin-2 (IL-2) receptors identified by the anti-Tac monoclonal antibody (MoAb), whereas normal resting cells do not. This observation provided the scientific basis for a trial of intravenous anti-Tac in the treatment of nine patients with ATL. The patients did not suffer untoward reactions and did not have a reduction in the normal formed elements of the blood, and only one of the nine produced antibodies to the anti-Tac MoAb. Three patients had transient mixed, partial, or complete remissions lasting from 1 to more than 8 months after anti-Tac therapy, as assessed by routine hematologic tests, immunofluorescence analysis of circulating cells, and molecular genetic analysis of HTLV-I provirus integration and of the T-cell receptor gene rearrangement. The precise mechanism of the antitumor effects is unclear; however, the use of a MoAb that prevents the interaction of IL-2 with its receptor on ATL cells provides a rational approach for the treatment of this malignancy.  相似文献   
997.
998.
MR imaging of optic pathways in patients with neurofibromatosis   总被引:1,自引:0,他引:1  
Twenty-one patients with documented neurofibromatosis had MR examinations to evaluate possible intracranial disease. In five cases the indication was a known or suspected optic glioma. Two patients were examined because of a history of seizures; the rest were examined as part of a baseline evaluation. Eighteen patients showed evidence of signal hyperintensity on T2-weighted images. Lesions involved the optic nerves, optic chiasm, optic tracts, lateral geniculate body, optic radiations, basal ganglia, periventricular white matter, cerebellar white matter, and dentate nucleus of the cerebellum. Comparison between MR and concurrent CT scans showed MR to be superior in demonstrating the posterior extent of optic-pathway gliomas. In addition, MR showed focal areas of hyperintensity in the basal ganglia, internal capsule, cerebellum, and/or white matter that were not detected on CT. Although we found MR to be superior to CT in detecting intracranial tumors in patients with neurofibromatosis, and in evaluating the extensive involvement of known lesions, the full clinical implications of our findings remain to be determined.  相似文献   
999.
1000.
OBJECTIVE: APA evaluated the Social Security Administration's (SSA's) medical standards and guidelines for determining disability due to mental impairment to determine how well the standards and guidelines operationalize the statutory definition of disability in a manner consistent with current psychiatric practice. METHOD: Seventy-two psychiatrists were trained in one of two procedures: those in the sequential evaluation condition were trained in the process and forms used by the SSA's reviewing medical consultants, and those in the statutory definition condition were trained in the statutory definition of disability and application of clinical judgment according to this standard. Decisions regarding claimant's ability or inability to work were recorded on an instrument designed for the study. Each condition consisted of 12 panels of three members. They reviewed 732 actual claims for disability benefits. The panelists reviewed claims independently, then rendered panel judgments. Each claim was reviewed by one panel in each condition. RESULTS: The proportion of agreement between conditions for panel decisions (0.77) was higher than chance agreement (kappa = 0.46). The high level of agreement on claims judged to have good medical evidence and on which confident decisions were made (proportion of agreement = 0.96, kappa = 0.78) suggests that disagreements largely reflected ambiguities in application of the standards and guidelines to more complex cases or those with inadequate information. CONCLUSIONS: The SSA's revised medical standards and guidelines reflect clinical decisions about ability to work based on the statute and, with procedural modifications, should be retained. The SSA should be involved in further systematic studies to develop a field of scientific inquiry into disability and psychiatric disorders.  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