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   335篇
  免费   29篇
  国内免费   3篇
耳鼻咽喉   5篇
儿科学   6篇
妇产科学   2篇
基础医学   50篇
口腔科学   8篇
临床医学   23篇
内科学   61篇
皮肤病学   7篇
神经病学   27篇
特种医学   24篇
外科学   60篇
综合类   8篇
一般理论   1篇
预防医学   25篇
眼科学   2篇
药学   16篇
中国医学   6篇
肿瘤学   36篇
  2023年   7篇
  2022年   17篇
  2021年   17篇
  2020年   15篇
  2019年   18篇
  2018年   21篇
  2017年   11篇
  2016年   5篇
  2015年   13篇
  2014年   16篇
  2013年   21篇
  2012年   22篇
  2011年   12篇
  2010年   5篇
  2009年   13篇
  2008年   18篇
  2007年   20篇
  2006年   12篇
  2005年   14篇
  2004年   16篇
  2003年   18篇
  2002年   5篇
  2001年   8篇
  2000年   10篇
  1999年   5篇
  1994年   1篇
  1993年   4篇
  1992年   4篇
  1991年   2篇
  1990年   4篇
  1989年   2篇
  1988年   4篇
  1987年   1篇
  1986年   3篇
  1985年   1篇
  1972年   1篇
  1935年   1篇
排序方式: 共有367条查询结果,搜索用时 296 毫秒
71.
研究了双茂基希夫碱稀土络合物/NaH体系催化1,5-己二烯的异构化反应。异构化反应生成1,4-己二烯、2,4-己二烯、1,3-己二烯、亚甲基环戊烷和甲基环戊烯的混合物。同时研究了异构化反应中不同催化剂、反应温度、催化剂用量和时间对异构化速率及产品组成的影响。产物中线型产物与环状产物的比率取决于所用的催化剂及反应条件。  相似文献   
72.
Stimulation of amylase secretion from parotid glands by beta-adrenergic agonists is mediated by the activation of adenylate cyclase and the resultant increase in cellular cAMP. Since NaF is known to increase adenylate cyclase activity and cAMP accumulation in intact cells, we investigated whether it would stimulate amylase secretion from isolated rat parotid gland cells. The results provide evidence that the addition of NaF (0.01-10 mmol/L) increased cAMP concentration (1.5-2.8-fold) in, and amylase secretion (16-93%) from, isolated parotid gland acinar cells. NaF was found to increase cAMP-dependent protein kinase activity ratios (51-84%) in a concentration- and time-dependent manner. The data suggest that the stimulation of amylase secretion from parotid gland cells by NaF may be mediated by an increase in the cellular cAMP concentration, which exerts its effect, at least in part, by increasing the activity of cAMP-dependent protein kinase.  相似文献   
73.
74.
75.

Background

We questioned whether the National Comprehensive Cancer Network recommendations for brain magnetic resonance imaging (MRI) for patients with stage ≥ IB non–small-cell lung cancer (NSCLC) was high-yield compared with American College of Clinical Pharmacy and National Institute for Health and Care Excellence guidelines recommending stage III and above NSCLC. We present the prevalence and factors predictive of asymptomatic brain metastases at diagnosis in patients with NSCLC without extracranial metastases.

Materials and Methods

A retrospective analysis of 193 consecutive, treatment-naïve patients with NSCLC diagnosed between January 2010 and August 2015 was performed. Exclusion criteria included no brain MRI staging, symptomatic brain metastases, or stage IV based on extracranial disease. Univariate and multivariate logistic regression was performed.

Results

The patient characteristics include median age of 65 years (range, 36-90 years), 51% adenocarcinoma/36% squamous carcinoma, and pre-MRI stage grouping of 31% I, 22% II, 34% IIIA, and 13% IIIB. The overall prevalence of brain metastases was 5.7% (n = 11). One (2.4%) stage IA and 1 (5.6%) stage IB patient had asymptomatic brain metastases at diagnosis, both were adenocarcinomas. On univariate analysis, increasing lymph nodal stage (P = .02), lymph nodal size > 2 cm (P = .009), multi-lymph nodal N1/N2 station involvement (P = .027), and overall stage (P = .005) were associated with asymptomatic brain metastases. On multivariate analysis, increasing lymph nodal size remained significant (odds ratio, 1.545; P = .009).

Conclusion

Our series shows a 5.7% rate of asymptomatic brain metastasis for patients with stage I to III NSCLC. Increasing lymph nodal size was the only predictor of asymptomatic brain metastases, suggesting over-utilization of MRI in early-stage disease, especially in lymph node-negative patients with NSCLC. Future efforts will explore the utility of baseline MRI in lymph node-positive stage II and all stage IIIA patients.  相似文献   
76.
77.
Intravascular large cell lymphoma (IVLCL) is a rare disease characterized by proliferation of malignant lymphocytes within the small blood vessel lumens. The association of IVLCL with autoimmune hemolytic anemia (AIHA) has been described in a single case report, but the true prevalence of this co‐occurrence is not known because of declining autopsy rates. Here, we report a case of a 41‐year‐old woman who carried a diagnosis of AIHA for 2 years, with repeated hemolytic episodes that were initially well controlled with immunomodulatory treatment. At her last presentation, the patient developed rapidly progressive neurologic symptoms and leukoencephalopathy on MRI; she died 4 weeks later with a clinical impression of thrombotic microangiopathy, a known complication of AIHA. At autopsy, the brain showed widespread platelet thrombi and intraparenchymal hemorrhages characteristic of this disorder. In addition, there was evidence of a clinically unsuspected IVLCL, most likely of B‐cell lineage. This case illustrates a potential association between IVLCL and AIHA, highlights the need for broad differential diagnosis in cases with atypical disease presentation or progression, and underlines the importance of autopsy in establishing the full cause of morbidity and mortality.  相似文献   
78.
79.
80.
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