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   1315篇
  免费   100篇
  国内免费   4篇
耳鼻咽喉   3篇
儿科学   27篇
妇产科学   5篇
基础医学   146篇
口腔科学   2篇
临床医学   161篇
内科学   176篇
皮肤病学   31篇
神经病学   492篇
特种医学   77篇
外科学   98篇
综合类   15篇
一般理论   1篇
预防医学   87篇
眼科学   8篇
药学   59篇
中国医学   1篇
肿瘤学   30篇
  2021年   13篇
  2020年   15篇
  2019年   11篇
  2018年   21篇
  2017年   10篇
  2016年   10篇
  2015年   17篇
  2014年   18篇
  2013年   29篇
  2012年   51篇
  2011年   58篇
  2010年   45篇
  2009年   32篇
  2008年   56篇
  2007年   69篇
  2006年   63篇
  2005年   65篇
  2004年   57篇
  2003年   49篇
  2002年   49篇
  2001年   45篇
  2000年   51篇
  1999年   35篇
  1998年   19篇
  1997年   22篇
  1996年   16篇
  1995年   14篇
  1994年   18篇
  1993年   18篇
  1992年   34篇
  1991年   21篇
  1990年   33篇
  1989年   27篇
  1988年   32篇
  1987年   22篇
  1986年   22篇
  1985年   28篇
  1984年   17篇
  1983年   16篇
  1982年   16篇
  1981年   13篇
  1980年   10篇
  1979年   19篇
  1978年   10篇
  1977年   11篇
  1976年   14篇
  1975年   10篇
  1974年   11篇
  1972年   10篇
  1968年   10篇
排序方式: 共有1419条查询结果,搜索用时 78 毫秒
11.
Summary Balloon atrial septostomy is an established method of palliation for several forms of congenital heart disease. Previously performed under fluoroscopic x-ray control, recent reports have demonstrated the utility of transthoracic echocardiographic monitoring. We report the first application of uniplane transesophageal echocardiography (TEE) (6.7-mm probe) as an alternative imaging modality for control of ballon atrial septostomy on neonates in the intensive care unit.  相似文献   
12.
To ascertain the magnetic resonance (MR) imaging characteristics of pheochromocytomas and paragangliomas and to compare MR with computed tomography (CT) and iodine-131 metaiodobenzylguanidine (I-131 MIBG), 19 patients (18 with pheochromocytomas, one with a paraganglioma) were studied. The 18 patients with pheochromocytomas had had positive findings with I-131 MIBG scintigraphy. Abdominal pheochromocytomas were generally hypointense compared with normal liver on T1-weighted MR images and extremely hyperintense on T2-weighted MR images. MR imaging was preferable to CT in the evaluation of primary pheochromocytomas due to superior tissue characterization, particularly in the patient with hypertension and borderline catecholamine levels. For patients with recurrent or metastatic disease, the data suggest that I-131 MIBG scintigraphy is the examination of choice.  相似文献   
13.
In a recent paper, we showed that the number of endoneurial microvessels per square millimeter and the average luminal area and size distribution of these microvessels are not significantly different in sural nerves of patients with diabetes mellitus as compared to control subjects. Mural area, especially the component due to basement membrane reduplication and cellular debris, was unequivocally increased in diabetes mellitus. Because these latter changes are associated with a decrease in periendothelial cell area, we hypothesized that cellular degeneration, especially of pericytes, may account for basement membrane reduplication and increased frequency of cellular debris. In the present study, we showed that endoneurial microvessels undergo a statistically significant increase in basement membrane area, mural area, and frequency of cellular debris in diabetics without polyneuropathy and an even greater increase in diabetics with polyneuropathy. We also found that duration of diabetes mellitus was significantly associated with area occupied by reduplicated basement membrane and cellular debris, but not with mural and periendothelial area. None of the examined measurements was associated with age. Since the microvessel abnormalities we describe are already present before the development of polyneuropathy and increase with severity of polyneuropathy, it is likely that they reflect functional derangements of pericytes and microvessel function which precede and might be implicated in fiber degeneration.  相似文献   
14.
In this study, the prevalence and severity of traumatic experiences as reported by patients with dissociative disorders and with other DSM-IV psychiatric diagnoses were compared. Furthermore, the predictive value of emotional, physical, and sexual trauma with respect to somatoform and psychological dissociation was analyzed. In contrast with comparison patients, dissociative disorder patients reported severe and multifaceted traumatization. Physical and sexual trauma predicted somatoform dissociation, sexual trauma predicted psychological dissociation as well. According to the memories of the dissociative disorder patients, this abuse occurred in an emotionally neglectful and abusive social context. Pathological dissociation was best predicted by early onset of reported intense, chronic and multiple traumatization. Methodological limitations restricting causal inferences between reported trauma and dissociation are discussed.  相似文献   
15.
D E Dyck 《AAOHN journal》1992,40(4):182-185
1. According to Edwards (1988), "Fitness to work means being able to do the tasks involved effectively and without risk to one's own, or to others' health and safety." 2. Travel hazards can be biological, chemical, physical, and psychological in nature. 3. Travel hazard management includes pre- and posttravel health assessments, immunization, use of antimalarials, travel kit preparation, health insurance coverage, compliance to country admission regulations, and country-specific health and cultural briefing. 4. Educational and preventive practices are needed to prepare employees for high risk international travel. Through counseling and advice, occupational health services can help employees and employers with health risk management. High risk travel can be lowered to a moderate-low risk situation.  相似文献   
16.
BACKGROUND: Co-morbidity within anxiety disorders, and between anxiety disorders and depression, is common. According to the theory of Gray and McNaughton, this co-morbidity is caused by recursive interconnections linking the brain regions involved in fear, anxiety and panic and by heritable personality traits such as neuroticism. In other words, co-morbidity can be explained by one disorder being an epiphenomenon of the other and by a partly shared genetic etiology. The aim of this paper is to evaluate the theory of Gray and McNaughton using the results of genetic epidemiological studies. METHOD: Twenty-three twin studies and 12 family studies on co-morbidity are reviewed. To compare the outcomes systematically, genetic and environmental correlations between disorders are calculated for the twin studies and the results from the family studies are summarized according to the method of Klein and Riso. RESULTS: Twin studies show that co-morbidity within anxiety disorders and between anxiety disorders and depression is explained by a shared genetic vulnerability for both disorders. Some family studies support this conclusion, but others suggest that co-morbidity is due to one disorder being an epiphenomenon of the other. CONCLUSIONS: Discrepancies between the twin and family studies seem partly due to differences in used methodology. The theory of Gray and McNaughton that neuroticism is a shared risk factor for anxiety and depression is supported. Further research should reveal the role of recursive interconnections linking brain regions. A model is proposed to simultaneously investigate the influence of neuroticism and recursive interconnections on co-morbidity.  相似文献   
17.
18.
To test whether immunohistochemical characterization of proteins in amyloid deposits in biopsied sural nerves gives reliable and useful diagnostic information using commercially available reagents, biopsy specimens of sural nerves from 38 patients with amyloid neuropathy were studied. Transthyretin (TTR) was detected in the amyloid deposits of 11 nerves, lambda light chains (LC) in 8 nerves, kappa LC in 7 nerves, and both lambda and kappa LC in 3 nerves. In 9 nerves, the amyloid deposits were too small to allow adequate immunohistochemical characterization of amyloid proteins in serial sections. Evidence that immunohistochemical characterization was correct came from: 1) evaluation of kin, 2) search for monoclonal proteins in the plasma, and 3) sequencing of the gene abnormalities in TTR+ cases. In 9 of 11 TTR+ cases, in which DNA could be obtained, sequencing of the gene showed that each of the 9 cases was heterozygous for a gene mutation; 7 had previously described mutations and 2 undescribed mutations. Therefore, in the nine sporadic cases without plasma monoclonal light chains, the immunohistochemical characterization correctly identified the protein in amyloid as transthyretin. Likewise, there was a high concordance between immunoglobulin light chains in plasma and light chains in amyloid in primary amyloidosis. Evaluation of the type, distribution, and severity of the neurologic symptoms and deficits showed: 1) the sensorimotor and autonomic neuropathy of amyloidosis characteristically affects proximal as well as distal limbs, and 2) the type of amyloidosis probably cannot be determined from the characteristics or severity of the neuropathy alone or from the location or size of amyloid deposits in nerve.  相似文献   
19.
The production of mouse serum amyloid P component (SAP), a major acute phase protein of liver origin, was studied immunocytochemically using the peroxidase staining technique. SAP was not detectable in the cytoplasm of hepatocytes from normal, unstimulated mice, nor was it observed before 24 h after an acute phase stimulus. 125I-labelled mouse SAP was cleared from the plasma in vivo with a half-life of 7.0-8.25 h in all animals studied including: normal mice of different strains with different genetically determined plasma SAP concentrations; mice undergoing acute phase responses with greatly elevated plasma SAP levels and mice with casein-induced amyloidosis. The circulating level of SAP is thus independent of its rate of clearance and catabolism and is determined by the rate of synthesis and/or secretion of SAP.  相似文献   
20.
The objective of this study was to evaluate the diagnostic performance of the Roche multiplex AMPLICOR Chlamydia trachomatis/Neisseria gonorrhoeae PCR test for the detection of Neisseria gonorrhoeae infection in female urine specimens and wet and dry endocervical swabs. Endocervical swabs and urine specimens were collected from 342 female sex workers from Cotonou, Benin, and were tested using the AMPLICOR C. trachomatis/N. gonorrhoeae test (Roche Diagnostic Systems, Inc., Branchburg, N.J.) with internal control detection. Endocervical swabs were also cultured on Thayer-Martin medium. A series of alternate standards that included a combination of all the tests but not the test being evaluated was used to assess the performance of the test with each type of specimen. The sensitivity, specificity, and positive and negative predictive values for the urine were 53.8, 98.9, 93.5, and 87.5%, respectively. Corresponding figures for the wet swab were 91.5, 100, 100, and 97.4%, respectively. Those for the dry swab were 96.3, 96.2, 88.5, and 98.8%, respectively. Based on this study, the AMPLICOR PCR assay showed a low sensitivity for detection of N. gonorrhoeae infection in urine specimens, whereas the test was found to be highly sensitive and specific with endocervical specimens.  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