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   71590篇
  免费   4186篇
  国内免费   258篇
耳鼻咽喉   682篇
儿科学   2453篇
妇产科学   1888篇
基础医学   10449篇
口腔科学   1083篇
临床医学   7168篇
内科学   15397篇
皮肤病学   1374篇
神经病学   7302篇
特种医学   1638篇
外国民族医学   3篇
外科学   6379篇
综合类   661篇
现状与发展   1篇
一般理论   54篇
预防医学   6953篇
眼科学   1264篇
药学   5356篇
中国医学   149篇
肿瘤学   5780篇
  2024年   371篇
  2023年   831篇
  2022年   1566篇
  2021年   2683篇
  2020年   1667篇
  2019年   2142篇
  2018年   2227篇
  2017年   1801篇
  2016年   1976篇
  2015年   2135篇
  2014年   2801篇
  2013年   3602篇
  2012年   5238篇
  2011年   5323篇
  2010年   2859篇
  2009年   2445篇
  2008年   4099篇
  2007年   4124篇
  2006年   3721篇
  2005年   3480篇
  2004年   3264篇
  2003年   2978篇
  2002年   2665篇
  2001年   771篇
  2000年   728篇
  1999年   703篇
  1998年   527篇
  1997年   447篇
  1996年   340篇
  1995年   349篇
  1994年   324篇
  1993年   284篇
  1992年   501篇
  1991年   481篇
  1990年   472篇
  1989年   423篇
  1988年   444篇
  1987年   422篇
  1986年   376篇
  1985年   350篇
  1984年   340篇
  1983年   281篇
  1982年   201篇
  1981年   175篇
  1980年   179篇
  1979年   246篇
  1978年   204篇
  1977年   176篇
  1976年   175篇
  1973年   193篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
52.
Patent foramen ovale (PFO) is a common congenital anatomical defect in the general population with a mean prevalence of 20 %. Transcranial Doppler sonography and echocardiography, both with infusion of agitated saline as an echo contrast, have been introduced for the diagnosis of PFO. Transesophageal echocardiography is considered the gold standard. Several studies have suggested an association between cryptogenetic stroke and PFO, but the role of this condition as a risk factor for stroke is still debated. The aims of this prospective multicentre study are the evaluation of PFO prevalence in the whole ischemic stroke population and the identification of a stroke recurrence profile risk in patients with PFO. All consecutive patients admitted for acute ischemic stroke and with a confirmed diagnosis at discharge are eligible cases for the study. Demographic and vascular risk factors are registered. Clinical severity is summarized by the National Institute of Health stroke scale. Echocardiographic and transcranial studies are performed in each patient to detect the presence of PFO. Prevalence of PFO will be calculated with 95 % CIs. Univariate analysis will be performed to detect the correlation of PFO with different registered factors and multivariable analysis with PFO as independent variable. The present study should contribute to better identify the role of PFO in ischemic stroke risk and recurrence-related events. Qualifying findings of the study are represented by the high number of enrolled patients, the prospective methodology of the study and the presence of secondary instrumental endpoints.  相似文献   
53.
54.
Autism spectrum disorder, severe behaviour problems and duplication of the Xq12 to Xq13 region have recently been described in three male relatives. To describe the psychiatric comorbidity and dysmorphic features, including craniosynostosis, of two male siblings with autism and duplication of the Xq13 to Xq21 region, and attempt to narrow down the number of duplicated genes proposed to be leading to global developmental delay and autism. We performed DNA sequencing of certain exons of the TWIST1 gene, the FGFR2 gene and the FGFR3 gene. We also performed microarray analysis of the DNA. In addition to autism, the two male siblings exhibited severe learning disability, self-injurious behaviour, temper tantrums and hyperactivity, and had no communicative language. Chromosomal analyses were normal. Neither of the two siblings showed mutations of the sequenced exons known to produce craniosynostosis. The microarray analysis detected an extra copy of a region on the long arm of chromosome X, chromosome band Xq13.1–q21.1. Comparison of our two cases with previously described patients allowed us to identify three genes predisposing for autism in the duplicated chromosomal region. Sagittal craniosynostosis is also a new finding linked to the duplication.  相似文献   
55.
56.
57.

Purpose

Laparoscopic hiatal hernia repair with additional fundoplication is a commonly recommended standard surgical treatment for symptomatic large hiatal hernias with paraesophageal involvement (PEH). However, due to the risk of persistent side effects, this method remains controversial. Laparoscopic mesh-augmented hiatoplasty without fundoplication (LMAH), which combines hiatal repair and mesh reinforcement, might therefore be an alternative.

Methods

In this retrospective study of 55 (25 male, 30 female) consecutive PEH patients, the perioperative course and symptomatic outcomes were analyzed after a mean follow-up of 72 months.

Results

The mean DeMeester symptom score decreased from 5.1 to 1.8 (P < 0.001) and the gas bloating value decreased from 1.2 to 0.5 (P = 0.001). The dysphagia value was 0.7 before surgery and 0.6 (P = 0.379) after surgery. The majority of the patients were able to belch and vomit (96 and 92 %, respectively). Acid-suppressive therapy on a regular basis was discontinued in 68 % of patients. In 4 % of patients, reoperation was necessary due to recurrent or persistent reflux. A mesh-related stenosis that required endoscopic dilatation occurred in 2 % of patients.

Conclusions

LMAH is feasible, safe and provides an anti-reflux effect, even without fundoplication. As operation-related side effects seem to be rare, LMAH is a potential treatment option for large hiatal hernias with paraesophageal involvement.  相似文献   
58.

Abstract

Open in a separate window

Introduction

Solitary bone plasmacytoma (SP) is a rare diagnosis for which the primary treatment is local radiotherapy. There is no established consensus suggesting a total spondylectomy in spinal SP.

Materials and Methods

We report the case of a 43-year-old woman with solitary plasmacytoma of the lumbar spine treated with complete vertebral resection. Radiographs, CT scan and MRI showed a single osteolytic lesion of the third lumbar vertebra. Further diagnostics following recommended algorithm for tumour screening were negative. Two times, biopsy showed no histological pathologies. Due to the instability of the spine with suspicious unknown lesion, we decided to perform a dorsal lumbar approach and instrumentation with complete resection of the posterior parts to prepare for a complete resection if mandatory. Resamples were taken and the bone surfaces sealed. Consecutive findings were positive for plasma cell infiltration of the respective vertebra, however not on the first pass, but after diagnostic pathological reference. Surgery was completed by total spondylectomy. Reference histological findings with restaging and cytogenetic risk analysis confirmed a non-high-risk solitary bone plasmacytoma, and the patient was scheduled for localized radiotherapy with 40 Gy.

Results

Follow-up examinations (53 months) showed no local recurrence or disease progression.

Discussion

There is no consensus in the literature regarding appropriate surgical approach and perioperative strategies in the treatment of solitary plasmacytoma. The finding of a solitary plasmacytoma of the spine was the determining factor for our decision to perform radical surgery with subsequent radiotherapy. The rationale for the chosen approach was to minimize the risk of local recurrence and to avoid conversion into multiple myeloma. The follow-up with 53 months is limited. However, discussion remains, if radical surgery in addition to local radiotherapy could be an alternative therapeutic approach depending on paraclinical parameters, age and cytogenetic risk analysis.  相似文献   
59.
Alternative splicing (AS) is a crucial step in gene expression. It is subject to intricate regulation, and its deregulation in cancer can lead to a wide array of neoplastic phenotypes. A large body of evidence implicates splice isoforms in most if not all hallmarks of cancer, including growth, apoptosis, invasion and metastasis, angiogenesis, and metabolism. AS has important clinical implications since it can be manipulated therapeutically to treat cancer and represents a mechanism of resistance to therapy. In prostate cancer (PCa) AS also plays a prominent role and this review will summarize the current knowledge of alternatively spliced genes with important functional consequences. We will highlight accumulating evidence on AS of the components of the two critical pathways in PCa: androgen receptor (AR) and phosphoinositide 3-kinase (PI3K). These observations together with data on dysregulation of splice factors in PCa suggest that AR and PI3K pathways may be interconnected with previously unappreciated splicing regulatory networks. In addition, we will discuss several lines of evidence implicating splicing regulation in the development of the castration resistance.  相似文献   
60.
Our understanding of human phase II metabolic pathways which facilitate detoxification and excretion of warfarin (Coumadin) is limited. The goal of this study was to test the hypothesis that there are specific human hepatic and extrahepatic UDP-glucuronosyltransferase (UGT) isozymes, which are responsible for conjugating warfarin and hydroxylated metabolites of warfarin. Glucuronidation activity of human liver microsomes (HLMs) and eight human recombinant UGTs toward (R)- and (S)-warfarin, racemic warfarin, and major cytochrome P450 metabolites of warfarin (4'-, 6-, 7-, 8-, and 10-hydroxywarfarin) has been assessed. HLMs, UGT1A1, 1A8, 1A9, and 1A10 showed glucuronidation activity toward 4'-, 6-, 7-, and/or 8-hydroxywarfarin with K(m) values ranging from 59 to 480 microM and V(max) values ranging from 0.03 to 0.78 microM/min/mg protein. Tandem mass spectrometry studies and structure comparisons suggested glucuronidation was occurring at the C4'-, C6-, C7-, and C8-positions. Of the hepatic UGT isozymes tested, UGT1A9 exclusively metabolized 8-hydroxywarfarin, whereas UGT1A1 metabolized 6-, 7-, and 8-hydroxywarfarin. Studies with extrahepatic UGT isoforms showed that UGT1A8 metabolized 7- and 8-hydroxywarfarin and that UGT1A10 glucuronidated 4'-, 6-, 7-, and 8-hydroxywarfarin. UGT1A4, 1A6, 1A7, and 2B7 did not have activity with any substrate, and none of the UGT isozymes evaluated catalyzed reactions with (R)- and (S)-warfarin, racemic warfarin, or 10-hydroxywarfarin. This is the first study identifying and characterizing specific human UGT isozymes, which glucuronidate major cytochrome P450 metabolites of warfarin with similar metabolic rates known to be associated with warfarin metabolism. Continued characterization of these pathways may enhance our ability to reduce life-threatening and costly complications associated with warfarin therapy.  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