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   10837篇
  免费   496篇
  国内免费   34篇
耳鼻咽喉   158篇
儿科学   139篇
妇产科学   139篇
基础医学   1525篇
口腔科学   419篇
临床医学   718篇
内科学   2558篇
皮肤病学   145篇
神经病学   741篇
特种医学   624篇
外科学   1673篇
综合类   62篇
一般理论   1篇
预防医学   393篇
眼科学   265篇
药学   731篇
中国医学   19篇
肿瘤学   1057篇
  2023年   60篇
  2022年   121篇
  2021年   206篇
  2020年   108篇
  2019年   128篇
  2018年   157篇
  2017年   126篇
  2016年   169篇
  2015年   188篇
  2014年   239篇
  2013年   270篇
  2012年   468篇
  2011年   511篇
  2010年   269篇
  2009年   268篇
  2008年   421篇
  2007年   478篇
  2006年   472篇
  2005年   436篇
  2004年   453篇
  2003年   491篇
  2002年   466篇
  2001年   414篇
  2000年   466篇
  1999年   414篇
  1998年   141篇
  1997年   125篇
  1996年   97篇
  1995年   82篇
  1994年   81篇
  1993年   88篇
  1992年   322篇
  1991年   294篇
  1990年   255篇
  1989年   233篇
  1988年   230篇
  1987年   210篇
  1986年   178篇
  1985年   161篇
  1984年   127篇
  1983年   111篇
  1979年   66篇
  1978年   51篇
  1977年   53篇
  1975年   61篇
  1973年   48篇
  1972年   57篇
  1971年   47篇
  1968年   60篇
  1967年   64篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Background: To identify the reasons for misdiagnosis of the degree of stromal invasion by uterine cervical cancer with various magnetic resonance sequences. Methods: T2-weighted, dynamic, and postcontrast T1-weighted images were obtained in the sagittal plane in 20 patients with uterine cervical cancer. After evaluating these sequences for the degree of stromal invasion, histologic specimens were directly correlated with these images. Results: The degree of stromal invasion was correctly diagnosed in 15 of the 20 cases on T2-weighted images, in 12 on dynamic images, and in eight on postcontrast T1-weighted images. All misdiagnoses were due to overestimation. Histologically, peritumoral stroma showed inflammation or edema in two patients, whereas no histological abnormality was found in the other patients. A hyperintense rim, i.e., a peritumoral enhanced ring-shaped structure, was observed on the enhanced images of five patients. The hyperintense rim corresponded to the periphery of the tumor in three patients and to the cervical stroma in two patients. Conclusion: T2-weighted images permitted the most accurate evaluation of stromal invasion by uterine tumors. Overdiagnosis may be due to an abnormal intensity of the cervical stroma, which was observed more frequently on dynamic and postcontrast T1-weighted images than on T2-weighted images. Received: 10 November 1995/Accepted after revision: 13 March 1996  相似文献   
992.

Background Context

The incidence of incidental durotomy (ID) during total en bloc spondylectomy (TES) tends to be higher than that during other spinal surgeries because of the peculiarities of TES, including its highly invasive nature, epidural tumor extension, and use in patients who often have complicated medical backgrounds. However, there have been no detailed reports on ID associated with TES.

Purpose

The study aimed to investigate ID during TES in detail.

Study Design

This is a retrospective review of prospectively collected data.

Patient Sample

The study included 105 consecutive patients with spinal tumor who underwent TES between May 2010 and February 2015 (59 men, 46 women; mean age, 54.0 years [range, 14–75 years] at the time of surgery).

Outcome Measures

Outcome measures included the incidence, risk factors, anatomical location, intraoperative maneuvers, and postoperative course of ID associated with TES.

Materials and Methods

Medical and operative records and imaging findings were reviewed. Univariate analysis and multivariable stepwise logistic regression models were used to identify independent risk factors for ID.

Results

Incidental durotomy occurred in 18 (17.1%) of the 105 patients. The univariate and multivariate analyses demonstrated that older age (adjusted odds ratio [aOR], 6.09; 95% confidence interval [CI], 1.17–31.76; p=.03), radiotherapy (RT) history (aOR, 5.31; 95% CI, 1.46–19.49; p=.01), and revision surgery (aOR, 19.42; 95% CI, 3.46–109.14; p<.01) were independent risk factors for ID. Incidental durotomy was more likely to occur during dissection of tumor tissues in proximity to the nerve root. Although all of the ID cases were primarily sutured and covered with polyglycolic acid mesh and fibrin glue spray, eight cases required additional intervention because of intractable postoperative cerebrospinal fluid leakage. Six of these eight had a history of RT.

Conclusions

Our results may help better identify high-risk patients for ID during TES, which may aid surgeons with optimal surgical decision making and in counseling patients on perioperative complications.  相似文献   
993.
994.
A simple and rapid enzyme-linked immunoassay for human erythrocyte carbonic anhydrase isozyme I was developed. The assay was found to be sensitive enough for the detection of nanogram amounts of the enzyme in incubation mixtures. The first incubation with anti-human carbonic anhydrase I IgG was carried out for 6 hours at room temperature. The second incubation of the enzyme was carried out in the presence of goat plasma C1q coupled with peroxidase for 1 h at room temperature. The enzymatic reaction was performed for 30 min using 2,2'-azino-di(3-ethyl-benzthiazoline sulfonate) as a substrate, and absorbance at 414 nm was recorded. Carbonic anhydrase I was assayed on the range of 1 to 200 ng/ml using this method. The levels of carbonic anhydrase I in K562 cells induced by erythropoietin and in other blood cells were determined. This enzyme-linked immunoassay has application for the study of developing erythroid cells.  相似文献   
995.
In anti-red blood cell autoantibody transgenic (autoAb Tg) mice almost all B cells are deleted except for B-1 cells in the peritoneal cavity and the gut. About one-half of the auto Ab Tg mice suffer from autoimmune hemolytic anemia (AIHA) in the conventional condition. Oral administration of lipopolysaccharides activates B-1 cells and induces autoimmune symptoms in the Tg mice, suggesting that the autoimmune disease in anti-RBC autoAb Tg mice is triggered by infections. To examine the association of bacterial infections with the generation of B-1 cells and the occurrence of the autoimmune disease, we analyzed anti-RBC autoAb Tg mice bred in germ-free and specific pathogen-free conditions. In germ-free conditions, few peritoneal B-1 cells were detected, while a significant number of peritoneal B-1 cells existed in specific pathogen-free conditions. In both conditions, no mice suffered from AIHA. However, when these Tg mice were transferred to the conventional condition or injected with lipopolysaccharide, peritoneal B-1 cells expanded and some of these mice suffered from AIHA. These results clearly showed that bacterial infections are responsible for both the expansion of B-1 cells and the onset of the autoimmune disease in these Tg mice.  相似文献   
996.
997.
Colonization ofHelicobacter felis was observed to continue for at least 24 weeks in a BALB/c mouse stomach after oral inoculation of the bacteria. Bacteria were observed on the surface of the gastric mucosa and in the gastric pits as is typically seen withHelicobacter pylori infection in the human stomach.H. felis-colonized mice were treated for 5 consecutive days with various chemotherapeutic regimens used againstH. pylori for humans. The status ofH. felis infection was then assessed by the urease test 2 weeks after the final treatment. The clearance rates were 100% for a triple combination of amoxicillin (15 mg/kg), metronidazole (10 mg/kg) and bismuth subnitrate (5 mg/kg), 71% for amoxicillin alone (15 mg/kg), 80% for metronidazole alone (15 mg/kg), and 0% for bismuth subnitrate (60 mg/kg) or omeprazole (60 mg/kg) alone. Bacterial recurrence occurred more often in mice treated with amoxicillin alone than with the triple regimen during the 24-week posttreatment period. These results were very similar to the efficacy of each regimen obtained in clinical trials. Thus, this mouse model usingH. felis may be useful for evaluating drugs or regimens for the treatment of humanH. pylori infections.  相似文献   
998.
To minimize the adverse effects of high-dose administration of steroids and cyclophosphamide in patients with myeloperoxidase (MPO) antineutrophil cytoplasmic antibody (ANCA), granulocytapheresis (GCAP) or leukocytapheresis (LCAP) was performed to reduce inflammation. Four patients with rapidly progressive glomerulonephritis (RPGN) and one patient with pulmonary hemorrhage due to MPO-ANCA-associated vasculitis were treated by cytapheresis. The prednisolone (PSL) dose was 0.28 +/- 0.15 mg/kg/day (mean +/- SD) (range 0.18-0.50 g/kg/day). In the 4 RPGN patients, the peak serum creatinine level was 3.7 +/- 1.9 mg/dl (range 1.7 to 5.6 mg/dl). GCAP was performed in 3 RPGN patients and in 1 pulmonary hemorrhage patient. LCAP was performed in 1 RPGN patient. In the 4 RPGN patients, renal function improved after combined therapy with cytapheresis and corticosteroids. In the pulmonary hemorrhage patient, evidence of pulmonary hemorrhage on chest computed tomography scanning diminished after combined therapy with cytapheresis and corticosteroids. Cytapheresis, when combined with a low-dose or intermediate-dose PSL regimen, is effective in the treatment of ANCA-associated vasculitis.  相似文献   
999.
We report a solitary intraperitoneal recurrence in a long-term survivor after rupture of hepatocellular carcinoma. Ultrasonography demonstrated the finding of a lobulated mass with a "mosaic" appearance. The patient underwent resection of this implant and is currently disease free. We emphasize the importance of periodic surveillance of disseminated metastases of this condition.  相似文献   
1000.
Several lines of evidence show the importance of angiotensin II (AII) in renal injuries, especially when hemodynamic abnormalities are involved. To elucidate the role of AII in immune-mediated renal injury, we studied anti-glomerular basement membrane (GBM) nephritis in AII type 1a receptor (AT1a)-deficient homozygous (AT1a-/-) and wild-type (AT1a+/+) mice. A transient activation of the renin-angiotensin system (RAS) was observed in both groups of mice at around day 1. A renal expression of monocyte chemoattractant protein-1 (MCP-1) was transiently induced at six hours in both groups, which was then downregulated at day 1. In the AT1a+/+ mice, after RAS activation, the glomerular expression of MCP-1 was exacerbated at days 7 and 14. Thereafter, severe proteinuria developed, and the renal expressions of transforming growth factor-beta1 (TGF-beta1) and collagen type I increased, resulting in severe glomerulosclerosis and interstitial fibrosis. In contrast, glomerular expression of MCP-1, proteinuria, and tissue damage were markedly ameliorated in the AT1a-/- mice. Because this amelioration is likely due to the lack of AT1a, we can conclude that AII action, mediated by AT1a, plays a pathogenic role in anti-GBM nephritis, in which AII may contribute to the exacerbation of glomerular MCP-1 expression. These results suggest the involvement of AII in immune-mediated renal injuries.  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