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   3833742篇
  免费   274343篇
  国内免费   9518篇
耳鼻咽喉   54568篇
儿科学   126008篇
妇产科学   106097篇
基础医学   552416篇
口腔科学   108437篇
临床医学   348132篇
内科学   743033篇
皮肤病学   90545篇
神经病学   309836篇
特种医学   147779篇
外国民族医学   1020篇
外科学   569461篇
综合类   82119篇
现状与发展   6篇
一般理论   1407篇
预防医学   297996篇
眼科学   89106篇
药学   279120篇
  77篇
中国医学   8131篇
肿瘤学   202309篇
  2018年   40818篇
  2017年   31298篇
  2016年   36007篇
  2015年   42331篇
  2014年   58169篇
  2013年   87717篇
  2012年   114011篇
  2011年   120827篇
  2010年   73673篇
  2009年   70495篇
  2008年   113030篇
  2007年   120208篇
  2006年   122080篇
  2005年   117161篇
  2004年   113088篇
  2003年   108060篇
  2002年   103574篇
  2001年   177203篇
  2000年   181952篇
  1999年   153126篇
  1998年   45002篇
  1997年   39773篇
  1996年   40344篇
  1995年   39140篇
  1994年   36441篇
  1993年   34060篇
  1992年   121767篇
  1991年   118222篇
  1990年   114716篇
  1989年   110732篇
  1988年   101794篇
  1987年   100036篇
  1986年   94272篇
  1985年   89923篇
  1984年   67641篇
  1983年   57324篇
  1982年   34132篇
  1981年   30702篇
  1979年   60974篇
  1978年   43579篇
  1977年   36882篇
  1976年   34386篇
  1975年   36997篇
  1974年   43877篇
  1973年   41923篇
  1972年   39192篇
  1971年   36446篇
  1970年   33826篇
  1969年   32182篇
  1968年   29465篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
91.
Abstract

Objectives: Overlapping decreases in extrastriatal dopamine D2/D3-receptor availability and glucose metabolism have been reported in subjects with schizophrenia. It remains unknown whether these findings are physiologically related or coincidental.

Methods: To ascertain this, we used two consecutive 18F-fluorodeoxyglucose and 18F-fallypride positron emission tomography scans in 19 healthy and 25 unmedicated schizophrenia subjects. Matrices of correlations between 18F-fluorodeoxyglucose uptake and 18F-fallypride binding in voxels at the same xyz location and AFNI-generated regions of interest were evaluated in both diagnostic groups.

Results: 18F-fluorodeoxyglucose uptake and 18F-fallypride binding potential were predominantly positively correlated across the striatal and extrastriatal grey matter in both healthy and schizophrenia subjects. In comparison to healthy subjects, significantly weaker correlations in subjects with schizophrenia were confirmed in the right cingulate gyrus and thalamus, including the mediodorsal, lateral dorsal, anterior, and midline nuclei. Schizophrenia subjects showed decreased D2/D3-receptor availability in the hypothalamus, mamillary bodies, thalamus and several thalamic nuclei, and increased glucose uptake in three lobules of the cerebellar vermis.

Conclusions: Dopaminergic system may be involved in modulation of grey matter metabolism and neurometabolic coupling in both healthy human brain and psychopathology. Hyperdopaminergic state in untreated schizophrenia may at least partly account for the corresponding decreases in grey matter metabolism.  相似文献   
92.
93.
Abstract

Grief, death, bereavement, and loss do not discriminate based on gender identity or sexual orientation. Limited attention has been given to the bereaved partners of transgender and gender non-conforming persons (TGNC). Despite recent efforts to protect the rights of TGNC persons, the death of a TGNC partner is often complicated, marked by family members and friends who might never have known or refused to acknowledge the deceased in his, her, or their preferred gender. The present study adopted a single case study design to examine the death of a TGNC spouse through the unique lens of a bereaved partner.  相似文献   
94.
ObjectiveTo evaluate the outcomes after septal myectomy in patients with obstructive hypertrophic cardiomyopathy according to atrial fibrillation and surgical ablation of atrial fibrillation.MethodsWe reviewed patients with obstructive hypertrophic cardiomyopathy who underwent septal myectomy at the Mayo Clinic from 2001 to 2016. History of atrial fibrillation was obtained from patient histories and electrocardiograms. All-cause mortality was the primary end point.ResultsA total of 2023 patients underwent septal myectomy, of whom 394 (19.5%) had at least 1 episode of atrial fibrillation preoperatively. Among patients with atrial fibrillation, 76 (19.3%) had only 1 known episode, 278 (70.6%) had recurrent paroxysmal atrial fibrillation, and 40 (10.2%) had persistent atrial fibrillation. Surgical ablation was performed in 190 patients at the time of septal myectomy, including 148 with pulmonary vein isolation and 42 with the classic maze procedure. Among all patients, operative mortality was 0.4%, and there were no early deaths in patients undergoing surgical ablation. Over a median follow-up of 5.6 years, patients with preoperative atrial fibrillation had increased mortality (hazard ratio, 1.36; 95% confidence interval, 0.97-1.91; P = .070) after multivariable adjustment for comorbidities. When considering the impact of atrial fibrillation with or without surgical treatment, the adjusted hazard ratio for mortality in patients undergoing ablation compared with no ablation was 0.93 (95% confidence interval, 0.52-1.69; P = .824).ConclusionsAtrial fibrillation is present preoperatively in one-fifth of patients with obstructive hypertrophic cardiomyopathy undergoing myectomy and showed a trend toward higher all-cause mortality. Survival of patients undergoing septal myectomy with preoperative atrial fibrillation was similar between those who did and did not receive concomitant surgical ablation.  相似文献   
95.
Graphical abstract summarizing the overall results of our study comparing reintervention for a main or central branch pulmonary artery reconstruction site and various patch materials. Autologous pericardium was associate with the lowest reintervention and was free. Multivariable analysis demonstrated lack of superiority of homograft branch patch, which clearly has a much higher cost.
  相似文献   
96.
97.
98.
99.
Abstract

Objective: To understand the origin of extremely high gonadotropin levels in a perimenopausal woman.

Methods: A 52-year-old woman with a 2?months of amenorrhea followed spontaneous menstrual cycles recovery was referred to our outpatient clinic with elevated follicle-stimulating hormone (FSH, 483 mUI/ml), luteinizing hormone (LH, 475 mUI/ml) and prolactin (PRL, 173?ng/ml). She was known to take levosulpiride. The gonadotropin levels did not fit with the clinical features.

Results: A gonadotroph tumor was ruled out. Further analysis confirmed constantly high FSH, LH and PRL levels. The measurements were repeated using different analytical platforms with different results. After serial dilutions, nonlinearity was present suggesting an immunoassay interference. After post-polyethylene glycol recovery, hormone levels appeared in the normal range. Anti-goat antibodies were recognized in the serum of the patient.

Conclusions: This case report shows a case of falsely abnormal high gonadotropin and PRL levels in a woman during menopause transition. In the clinical practice the evaluation of gonadotropin profile is not recommended at this age, but the abnormal levels stimulated further evaluation. An interference in the assay due to anti-goat antibodies resulted in abnormally high level of FSH and LH. A strict collaboration between clinicians and the laboratory is needed, when laboratory findings do not correspond to clinical findings.  相似文献   
100.
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