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   229篇
  免费   15篇
  国内免费   1篇
儿科学   8篇
妇产科学   2篇
基础医学   31篇
临床医学   4篇
内科学   36篇
皮肤病学   5篇
神经病学   106篇
特种医学   4篇
外科学   13篇
预防医学   14篇
眼科学   3篇
药学   11篇
肿瘤学   8篇
  2023年   1篇
  2022年   8篇
  2021年   8篇
  2020年   13篇
  2019年   1篇
  2018年   9篇
  2017年   3篇
  2016年   2篇
  2015年   2篇
  2014年   7篇
  2013年   9篇
  2012年   17篇
  2011年   19篇
  2010年   3篇
  2009年   3篇
  2008年   9篇
  2007年   7篇
  2006年   8篇
  2005年   7篇
  2004年   5篇
  2003年   4篇
  2002年   8篇
  2001年   5篇
  2000年   12篇
  1999年   18篇
  1998年   5篇
  1997年   9篇
  1996年   3篇
  1995年   4篇
  1994年   3篇
  1993年   3篇
  1992年   5篇
  1991年   5篇
  1990年   5篇
  1989年   2篇
  1988年   1篇
  1987年   4篇
  1986年   2篇
  1985年   2篇
  1984年   2篇
  1983年   1篇
  1974年   1篇
排序方式: 共有245条查询结果,搜索用时 0 毫秒
181.
The recurrence rates during lithium preventive treatment were investigated in a sample of 270 Mood Disorder subjects subdivided according to their onset time for lithium prophylaxis as very early (within 5 years from the onset of illness), early (6–10 years), late (11–20 years) and very late (more than 21 years). 131 subjects of the sample followed for 4 years prolonged the observation for a further period of 8 years. Results indicated that beginning lithium therapy within the first ten years of illness predicts better preventive outcomes than beginning prophylaxis later, both in major depression, recurrent and bipolar patients. Received: 3 August 1998 / Accepted: 23 June 1999  相似文献   
182.
183.
184.
ABSTRACT

The emerging, next generation of people engaged as managers in agriculture differs from the “baby boomer” farm generation that relishes certain traditions and an agrarian lifestyle. These futuristic producers and managers have been raised in a society that promulgates safety environment rules. They have witnessed lives saved by automobile seatbelts and lives improved from clean air and water. They know the basic cost of effective safety compliance is relatively fixed, regardless of the number of employees, and they are willing to invest resources that ensure a culture of safety, because it is economically beneficial, socially responsible, and probably required by the companies to whom they need to market their products. These same millennials understand that society and their customers will not continue to tolerate the high rate of agricultural injuries and deaths indefinitely. Public policy as a means to improve agricultural workers’ safety and health is likely to be less resisted by the next generation of farmers, ranchers, producers, and agribusiness leaders who, regardless of legal or regulatory pressure, will implement internal business policies emphasizing safety, health, sustainability, and social justness as they understand it.  相似文献   
185.
Establishment of latently infected cell lines from primary effusion lymphomas (PEL) presently is the most efficient system for the propagation of clinical strains of human herpesvirus 8 (HHV-8) in culture. Here we describe a new approach to culture productively replicating HHV-8 from patient samples. A BJAB-derived B-cell line, BBF, was found to retain HHV-8 longer, to support the latent and lytic replication programs, and to produce transmissible virus. Supernatants from n-butyrate-treated peripheral blood mononuclear cells of 24 HHV-8-seropositive renal transplant recipients were used to infect BBF cells, and replicating virus was detected in cultures from 11 patients. Moreover, BBF cells infected with saliva strains showed a highly productive profile regardless of the initial viral load, which confirms that infectious HHV-8 can be present in saliva and also suggests that saliva strains may exhibit a high tropism for B lymphocytes. In conclusion, we established an in vitro system that efficiently detects HHV-8 in samples with low viral loads and that produces infectious progeny. BBF cells can be used to propagate HHV-8 from different biological samples as well as to clarify important issues related to virus-cell interactions in a context distinct from endothelial and PEL-derived cell lines.  相似文献   
186.
187.
188.
INTRODUCTION: Measurement of brain volume on magnetic resonance imaging (MRI) scans is regarded as an objective marker of multiple sclerosis (MS) severity with the potential to monitor treatment efficacy accurately. This study was performed to assess the variability of brain MRI volume measurements. PATIENTS AND METHODS: We studied nine patients with relapsing-remitting MS, who were imaged on two occasions (separated by an interval of 24 h) using two different MR scanners and fast fluid-attenuated inversion recovery (fast-FLAIR) sequences. The whole brain volume computed from each image was measured three times by three observers using a seed-growing technique based on signal intensity thresholding. Intra-observer, inter-observer and inter-scanner variabilities were expressed as coefficients of variations (COVs). The inter-scanner variability included not only the intra-observer variation but also the repositioning variability and the variation in observed brain volume caused by different scanner hardware and sequence implementations. RESULTS: There was no statistically significant difference in patients' brain volume values between observers (P=0.82) or between scanners (P=0.30). The mean intra-observer COV was 1.2% (s.e.=0.4%), the mean inter-observer COV was 1.8% (s.e.=0.8%) and the mean inter-scanner COV was 2.4% (s.e.=1.2%). The intra-observer variance was not statistically different from those found between observers (P=0.83) or scanners (P=0.44). CONCLUSION: The intra-observer variability in brain volume measurements found in this study was within the range of intra-observer variability found in previous studies. This study shows that the use of different observers and MR scanners has only a small influence on the measured brain volume and does not affect the reproducibility of this measurement greatly.  相似文献   
189.
190.
In this study we investigated the molecular bases of the β-thalassemia intermedia phenotype in six patients belonging to two unrelated families of Sardinian descent. Sequence analysis of the β globin gene from these patients detected, as the sole abnormality, the heterozygosity for the codon 39 nonsense mutation. The Aγ and Gγ promoters as well as the HS2 and HS3 core sequences of the β globin LCR from these patients, did not show any non-polymorphic nucleotide variation from the consensus sequence. One of the parents was heterozygous for codon 39 nonsense mutation but showed the β-thalassemia carrier phenotype; the other was hematologically normal and had an entirely normal β globin gene sequence. In both families, other members showed the typical hematological phenotype, clinically silent, of heterozygous β thalassemia. To explain the thalassemia intermedia phenotype, we postulated the presence of an unknown molecular defect interacting with the β globin gene mutation. Haplotype analysis excluded that this postulated defect lies in the β globin gene cluster. Am. J. Hematol. 57:43–47, 1998. © 1998 Wiley-Liss, Inc.  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