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   5639篇
  免费   303篇
  国内免费   74篇
耳鼻咽喉   50篇
儿科学   172篇
妇产科学   97篇
基础医学   683篇
口腔科学   197篇
临床医学   363篇
内科学   1435篇
皮肤病学   112篇
神经病学   276篇
特种医学   326篇
外科学   1181篇
综合类   13篇
预防医学   87篇
眼科学   38篇
药学   291篇
中国医学   8篇
肿瘤学   687篇
  2023年   38篇
  2022年   73篇
  2021年   116篇
  2020年   87篇
  2019年   115篇
  2018年   142篇
  2017年   115篇
  2016年   144篇
  2015年   170篇
  2014年   219篇
  2013年   248篇
  2012年   387篇
  2011年   398篇
  2010年   203篇
  2009年   159篇
  2008年   355篇
  2007年   400篇
  2006年   366篇
  2005年   377篇
  2004年   336篇
  2003年   326篇
  2002年   327篇
  2001年   52篇
  2000年   51篇
  1999年   52篇
  1998年   73篇
  1997年   47篇
  1996年   66篇
  1995年   40篇
  1994年   62篇
  1993年   36篇
  1992年   47篇
  1991年   42篇
  1990年   29篇
  1989年   28篇
  1988年   21篇
  1987年   26篇
  1986年   18篇
  1985年   20篇
  1984年   29篇
  1983年   16篇
  1982年   27篇
  1981年   14篇
  1980年   15篇
  1979年   15篇
  1978年   15篇
  1977年   12篇
  1976年   8篇
  1975年   8篇
  1974年   10篇
排序方式: 共有6016条查询结果,搜索用时 31 毫秒
991.
992.
993.
994.
Lugol chromoendoscopy is useful for the detection of early esophageal squamous cell cancer (ESCC). Multiple lugol-voiding lesions (LVLs) on lugol chromoendoscopy are associated with a very high risk of multiple cancers arising in the esophagus. Due to the widespread use of narrow band image technology in many institutions, esophageal cancer without LVLs in the background esophagus is sometimes detected. This retrospective study aims to clarify the clinical characteristic of esophageal cancer without LVLs in the background esophagus. A total of 191 consecutive patients with 204 ESCCs had undergone endoscopic submucosal dissection (ESD) from 2011 and 2014. Amongst these lesions, the number of LVLs in the background esophagus per endoscopic view was counted excluding main lesion, and the grading was divided into no LVLs ESCC (nL-ESCC) group and LVLs ESCC (L-ESCC) group. This study evaluated the clinical characteristics and the cumulative incidence of metachronous ESCC after ESD in both groups. Thirty-six patients with 36 lesions and 155 patients with 168 lesions were separated into the nL-ESCC group and L-ESCC group, respectively. On multivariate analysis, the nL-ESCC group was found to be more common in females, who were non-drinkers, or with erosive esophagitis. During follow-up periods, the cumulative incidence of metachronous ESCC at 3-years was 14.4% and 0.00% in the L-ESCC and nL-ESCC groups, respectively (P < 0.01). Our study showed that esophageal cancer without LVLs in the background esophagus was mostly occurred in females, who were non-drinkers, or with erosive esophagitis, which are uncommon features of ESCC.  相似文献   
995.
The influence of an oxygen‐inhibited layer (OIL) on the shear bond strength (SBS) to enamel and surface free‐energy (SFE) of adhesive systems was investigated. The adhesive systems tested were Scotchbond Multipurpose (SM), Clearfil SE Bond (CS), and Scotchbond Universal (SU). Resin composite was bonded to bovine enamel surfaces to determine the SBS, with and without an OIL, of adhesives. The SFE of cured adhesives with and without an OIL were determined by measuring the contact angles of three test liquids. There were no significant differences in the mean SBS of SM and CS specimens with or without an OIL; however, the mean SBS of SU specimens with an OIL was significantly higher than that of SU specimens without an OIL. For all three systems, the mean total SFE (γS), polarity force (), and hydrogen bonding force () values of cured adhesives with an OIL were significantly higher than those of cured adhesives without an OIL. The results of this study indicate that the presence of an OIL promotes higher SBS of a single‐step self‐etch adhesive system, but not of a three‐step or a two‐step self‐etch primer system. The SFE values of cured adhesives with an OIL were significantly higher than those without an OIL. The SFE characteristics of the OIL of adhesives differed depending on the type of adhesive.  相似文献   
996.
An arteriovenous malformation of the pancreas is a very rare disease, but its presentation is distinct and unique. In this report, we describe a patient who presented with this malformation which was localized in the tail of pancreas and demonstrated by abnormal angiography findings. The patient was a 60-year-old male with severe left hypochondralgia. Angiography revealed an increased blood volume in the tail of the pancreas with arteriovenous shunting. Secondary pancreatitis caused by the arteriovenous malformation was suspected by abnormal laboratory data, and confirmed by histology from the resected tail of the pancreas. This is a very rare report in which pancreatic arteriovenous malformation involving a pancreaticovenous fistula was confirmed by endoscopic retrograde cholangiopancreatography (ERCP).  相似文献   
997.
Anastomotic recurrence after sphincter-saving resection for rectal cancer   总被引:8,自引:0,他引:8  
A retrospective study of anastomotic recurrence after sphincter-saving resection for rectal cancer is presented. During the 21 years from 1962 to 1982, 273 patients with rectal cancer underwent sphincter-saving resection and 30 (11 percent) of them had anastomotic recurrences. Computer analysis of 69 variables was undertaken to identify factors contributing to the anastomotic recurrence, with special reference to the length of distal clearance of the bowel. There was no significant correlation between the incidence of recurrence and the length of distal clearance of the bowel, if the latter was over 2 cm. There appears to be justification for carrying out a curative sphincter-saving operation for cases in which more than a 2-cm distal margin can be afforded. However, for cancers of the infiltrating type, annular growths, invasion to adjacent organs or mucinous features, a more extensive distal clearance of the bowel is necessary, and the Miles operation should be performed.  相似文献   
998.
An event-related fMRI technique was used to assess neural responses to financial reward and penalty during a simple gambling task. We attempted to determine whether brain activities are dependent on the unique context of an event sequence. Thirty-six healthy volunteers participated in the study. The task was to guess the color of the suit of a card on each trial and to respond by pressing a button. Every correct response ("win") and incorrect response ("loss") was associated with financial reward and penalty, respectively. The magnitude of reward or penalty in each trial did not change; however, the subjects' self-reported emotional arousal was significantly higher for the events of "the fourth win of four wins in a row" and "the fourth loss of four losses in a row." We also found that the bilateral anterior cingulate and medial prefrontal cortices were specifically activated when the subjects experienced "the fourth win of four wins in a row" and "the fourth loss of four losses in a row." When the subjects experienced "a win following four losses in a row" or "a loss following four wins in a row," the right dorsolateral prefrontal cortex was specifically activated. Our data indicate that there exist brain activities associated with the event-sequence context in which abstract reward or penalty is received. These context-dependent activities appear to be crucial for adapting oneself to new circumstances and may account for clinical symptoms of various mental illnesses in which dysfunction of these regions has been reported.  相似文献   
999.
Azathioprine (AZA) is an immunosuppressant commonly used for organ transplantation and autoimmune diseases. Allergic side effects of AZA are rare, and reported allergic skin eruptions from AZA are very limited in Japan. We report AZA-induced drug eruption that developed in two cases of systemic scleroderma with polymyositis. One case presented with Stevens-Johnson syndrome, and the other had systemic papular erythema. The stimulation indices of the drug-induced lymphocyte stimulation test (DLST) for AZA in these two patients were as high as 2,180% and 430%, respectively, but those of healthy volunteers were under 120% without nonspecific suppression of lymphocyte proliferation. Other drugs used simultaneously were ruled out by patch and challenge tests. The challenge test for Stevens-Johnson syndrome type drug allergy is very risky. DLST is a good diagnostic tool for AZA allergy, especially for severe drug allergy cases.  相似文献   
1000.
Epidermolytic palmoplantar keratoderma (EPPK) is an autosomal dominant inherited skin disorder characterized by hyperkeratosis of the skin over the palms and soles. Mutations in keratin 9 gene (KRT9) have been demonstrated in EPPK. In this study, we screened a Japanese family with EPPK for KRT9 mutation by polymerase chain reaction amplification of genomic sequences, followed by heteroduplex analysis and direct nucleotide sequencing. The mutation consisted of a G-to-C transversion at codon 162 in exon 1, which was located in the hot spot of the mutations that have been reported previously (R162Q and R162W). However, the amino acid substitution was proline for arginine (R162P) in the 1A rod domain, the highly conserved helix initiation motif of keratin 9. Our result illustrates the repertoire of KRT9 mutation underlying the occurrence of EPPK in a Japanese family and is an important contribution to the investigation of the genotype/phenotype correlation.  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