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   21426篇
  免费   1005篇
  国内免费   96篇
耳鼻咽喉   201篇
儿科学   397篇
妇产科学   415篇
基础医学   2982篇
口腔科学   440篇
临床医学   1336篇
内科学   5116篇
皮肤病学   317篇
神经病学   2065篇
特种医学   822篇
外科学   3213篇
综合类   87篇
一般理论   7篇
预防医学   723篇
眼科学   417篇
药学   1357篇
中国医学   26篇
肿瘤学   2606篇
  2022年   203篇
  2021年   351篇
  2020年   196篇
  2019年   265篇
  2018年   328篇
  2017年   274篇
  2016年   306篇
  2015年   335篇
  2014年   441篇
  2013年   588篇
  2012年   942篇
  2011年   1001篇
  2010年   532篇
  2009年   476篇
  2008年   826篇
  2007年   996篇
  2006年   924篇
  2005年   902篇
  2004年   878篇
  2003年   875篇
  2002年   966篇
  2001年   673篇
  2000年   737篇
  1999年   684篇
  1998年   285篇
  1997年   219篇
  1996年   208篇
  1995年   206篇
  1994年   204篇
  1993年   186篇
  1992年   631篇
  1991年   552篇
  1990年   549篇
  1989年   559篇
  1988年   502篇
  1987年   485篇
  1986年   436篇
  1985年   438篇
  1984年   252篇
  1983年   218篇
  1982年   99篇
  1979年   232篇
  1978年   130篇
  1977年   100篇
  1975年   98篇
  1974年   98篇
  1973年   100篇
  1970年   100篇
  1969年   115篇
  1968年   94篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
BK polyomavirus (BKPyV) is recognized as a pathogen that causes diseases such as hemorrhagic cystitis and nephritis after allogeneic hematopoietic stem cell transplantation (HSCT) or renal transplantation. BKPyV‐associated disease is thought to occur through reactivation under immunosuppression. However, the possibility of its nosocomial transmission and the clinical significance of such transmission have not been elucidated. During a 6‐month period, nine adult patients (median age: 47 years) who had hematological disorders and who were treated with HSCT (n = 7) or chemotherapy (n = 2) in a single hematology department developed hemorrhagic cystitis due to BKPyV infection. The polymerase chain reaction products of BKPyV DNA obtained from each patient were sequenced. Of the nine patients, six had subtype I, 2 had subtype IV, and 1 had subtype II or III. In the alignment of sequences, four and two of the six subtype I strains were completely homologous (100%). These results strongly suggest that BKPyV has the potential to cause nosocomial infection within a medical facility, especially among recipients of HSCT. Further studies are clearly warranted to elucidate the route(s) of BKPyV transmission in order to establish optimal infection control.  相似文献   
992.
We hypothesized that environmental factors might affect the relationship between genetic predisposition and the risk of bone mineral density (BMD) loss. Cases were 114 Japanese women with a confirmed diagnosis of postmenopausal osteoporosis and controls were 171 general Japanese women. Genetic risk of SNPs in the estrogen receptors was analyzed by a case–control study. The interaction between gene and environmental factors for osteoporosis were assessed by a case‐only design. Significant increases in osteoporosis risk were observed with minor alleles of rs2077647 located in the first exon and rs2234693 located in the first intron of estrogen receptor α (ESRα). Haplotype CC at these risk SNPs was strongly associated with osteoporosis risk (odds ratio [OR] = 3.15, 95% confidence interval [CI] = 1.83–5.41). There was a statistically significant interaction between haplotype CC and alcohol drinking; moderate alcohol consumption decreased genetic risk of osteoporosis (OR = 0.22, 95%CI = 0.05–0.83). © 2012 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 30:1529–1534, 2012  相似文献   
993.
994.
There is currently accumulating evidence for bidirectional communication between the neuroendocrine and immune systems. Various cytokines have been suggested to be involved in the stimulation of stress hormone secretion during the times of infection and inflammation. To assess the possible involvement and pathophysiologic significance of cytokines in the mechanisms responsible for the perioperative stress response of the hypothalamo-pituitary-adrenal axis, we observed the changes of plasma adrenocorticotropic hormone and cortisol levels together with those of plasma endotoxin and cytokine levels. In patients undergoing pancreatoduodenectomy, perioperative stimulation of adrenocorticotropic hormone and cortisol secretion was accompanied by a significant elevation of plasma cytokine levels. Application of epidural block up to the upper thoracic levels failed to suppress this stress response effectively. In patients undergoing unilateral total hip replacement, the response of plasma hormone levels was smaller and briefer with no significant increase of plasma cytokine levels. Application of epidural block up to the lower thoracic levels suppressed this hormonal response almost completely. In patients undergoing pancreatoduodenectomy, a significant elevation of plasma endotoxin level was followed by a gradual but significant elevation of plasma tumor necrosis factor alpha and interleukin-6 levels. It seems likely that the stimulatory effects of these cytokines on the secretion of adrenocorticotropic hormone and cortisol might be involved in the development of the greater and more prolonged stress response of hypothalamo-pituitary-adrenal axis. Our present study suggests that not only neural input from the surgical wound but also stimulation of cytokine production were responsible for the development of the stress response of the hypothalamo-pituitary-adrenal axis during and after upper abdominal surgery.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
995.
996.

Background

Peritoneal relapse is the most common pattern of tumor progression in advanced gastric cancer. Clinicopathological findings are sometimes inadequate for predicting peritoneal relapse. The aim of this study was to identify patients at high risk of peritoneal relapse in a prospective study based on molecular prediction.

Methods

RNA samples from 141 primary gastric cancer tissues after curative surgery were profiled using oligonucleotide microarrays covering 30,000 human probes. Firstly, we constructed a molecular prediction system and validated its robustness and prognostic validity by 500 times multiple validation by repeated random sampling in a retrospective set of 56 (38 relapse-free and 18 peritoneal-relapse) patients. Secondly, we applied this prediction to 85 patients of the prospective set to assess predictive accuracy and prognostic validity.

Results

In the retrospective phase, repeated random validation yielded ~68% predictive accuracy and a 22-gene expression profile associated with peritoneal relapse was identified. The prediction system identified patients with poor prognosis. In the prospective phase, the molecular prediction yielded 76.9% overall accuracy. Kaplan–Meier analysis of peritoneal-relapse-free survival showed a significant difference between the “good signature group” and “poor signature group” (log-rank p = 0.0017). Multivariate analysis by Cox regression hazards model identified the molecular prediction as the only independent prognostic factor for peritoneal relapse.

Conclusions

Gene expression profile inherent to primary gastric cancer tissues can be useful in prospective prediction of peritoneal relapse after curative surgery, potentially allowing individualized postoperative management to improve the prognosis of patients with advanced gastric cancer.  相似文献   
997.
Background/purpose  Pancreatic fistula, which is one of the main causes of late postpancreatectomy hemorrhage (PPH), is a common complication of pancreatoduodenectomy (PD). It may erode the anastomosis site and vascular wall in its vicinity, resulting in pseudoaneurysm formation and/or the rupture of major vessels. To protect the vessels near the area for pancreaticojejunostomy from potential pancreatic fistula, we have adopted a surgical option by which such vessels are separated from the pancreaticojejunostomy using a pedicled falciform ligament. We reviewed 36 patients who underwent PD that included this option. Methods  After the PD was completed (before reconstructions), the pedicled falciform ligament was spread widely on the major vessels exposed during resection, and was fixed to the surrounding retroperitoneal connective tissue. These procedures enabled the complete separation of these vessels from the pancreaticojejunostomy. Results  The mobilization and placement of the falciform ligament in the space between the pancreaticojejunostomy and the major vessels were successfully carried out without any complications. Although ten (28%) patients developed pancreatic fistula and three (8%) developed intraabdominal infection, none of the patients developed late PPH. Conclusions  The present surgical option is technically simple and easy, and may be an effective prophylactic measure against late PPH following PD.  相似文献   
998.
999.
1000.
A segment of the transverse colon can be used for gastric reconstruction after a total gastrectomy. This report presents the case of a 68-year-old woman with primary adenocarcinoma of the colon in a segment used for reconstruction after a total gastrectomy. The interposed colon developed colon carcinoma 9 years after the gastric reconstruction. The possibility of a primary carcinoma arising in a gastric colon interposition must be considered when employing the transverse colon as a gastric substitute.  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