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   28071篇
  免费   2580篇
  国内免费   92篇
耳鼻咽喉   262篇
儿科学   962篇
妇产科学   624篇
基础医学   3901篇
口腔科学   510篇
临床医学   3086篇
内科学   5826篇
皮肤病学   587篇
神经病学   2811篇
特种医学   712篇
外国民族医学   1篇
外科学   3314篇
综合类   394篇
一般理论   25篇
预防医学   2688篇
眼科学   517篇
药学   2257篇
中国医学   46篇
肿瘤学   2220篇
  2023年   226篇
  2022年   371篇
  2021年   729篇
  2020年   448篇
  2019年   651篇
  2018年   757篇
  2017年   550篇
  2016年   585篇
  2015年   681篇
  2014年   921篇
  2013年   1174篇
  2012年   1852篇
  2011年   1789篇
  2010年   1029篇
  2009年   924篇
  2008年   1588篇
  2007年   1597篇
  2006年   1519篇
  2005年   1422篇
  2004年   1359篇
  2003年   1266篇
  2002年   1123篇
  2001年   563篇
  2000年   497篇
  1999年   487篇
  1998年   274篇
  1997年   261篇
  1996年   239篇
  1995年   221篇
  1994年   191篇
  1993年   192篇
  1992年   439篇
  1991年   368篇
  1990年   317篇
  1989年   309篇
  1988年   345篇
  1987年   303篇
  1986年   271篇
  1985年   234篇
  1984年   264篇
  1983年   203篇
  1982年   151篇
  1981年   115篇
  1980年   121篇
  1979年   199篇
  1978年   128篇
  1976年   130篇
  1975年   125篇
  1974年   120篇
  1972年   120篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
2.
3.

Background

In the emergency department, rib fractures are a common finding in patients who sustain chest trauma. Rib fractures may be a sign of significant, underlying pathology, especially in the elderly patients where rib fractures are associated with significant morbidity and mortality. To date, no studies have evaluated the ability of ultrasound to detect rib fractures using cadaver models and subsequently use this model as a teaching tool.

Objectives

The purpose of this study was to determine if it is possible to generate rib fractures on cadaver models which could be accurately identified using ultrasound.

Methods

This was a cross-sectional study performed during one session at a cadaver lab. A single hemithorax from four adult cadavers were used as models. Single rib fractures on each of rib five through eight were created. Four subjects, blinded to the normal versus fractured ribs, were asked to identify the presence of a fracture on each rib.

Results

A total of 8 of 16 potential ribs had fractured induced by study staff. Mean accuracy was 55% for all subjects. The overall sensitivity and specificity for detecting rib fractures was 50% (CI: 31.89–68.11) and 59.38% (CI: 35.69–73.55) respectively. The overall PPV and NPV was 55.17% and 54.29% respectively.

Conclusions

In this pilot study, subjects were not able to detect induced rib fractures using ultrasound on cadaver models. The use of this model as a teaching tool in the detection of rib fractures requires further investigation.  相似文献   
4.
We report on 3 patients with pseudoathetosis, which are involuntary, slow, writhing movements due to loss of proprioception.  相似文献   
5.
. Neutrophil-mediated tissue damage has been implicated in the pathogenesis of diarrhoea-associated haemolytic uraemic syndrome (D+ HUS). This study evaluates priming and activation of the neutrophil oxidative burst in D+ HUS using chemiluminescent techniques. Peripheral blood neutrophils from 11 children with acute D+ HUS were examined. No difference was found in the oxidative burst of neutrophils from patients and controls. Serum elastase levels were measured in 8 patients and found to be significantly elevated. Although elastase results suggest neutrophil activation, chemiluminescence studies do not confirm this in the peripheral blood neutrophil. This does not support a significant role for circulating agents in priming and activating the peripheral blood neutrophil. Received August 17, 1995; received in revised form and accepted November 27, 1995  相似文献   
6.
SUMMARY. Samples from 1828 donations were screened for anti-HBc at seven sites in the UK using kits supplied by 10 manufacturers. Only 10 (0.55%) donations were considered to have true anti-HBc reactivity and these were detected by all 10 kits. Additional markers of HBV infection were found in nine of these 10 donations. Additional reactives were found by all kits, the number ranging from 1 to 43.
In the four more specific kits, the 10 true reactives were clearly distinguished from the 'false reactives' by the strength of the reaction. It is concluded that the reliance on a single ELISA test for anti-HBc diagnosis is unwise. The use of a second test known to be more specific than the screening ELISA is recommended.  相似文献   
7.
The clinical, radiologic, and histopathologic findings of a case of bilateral dacryops is reported in a 49-year-old man. The patient presented with cystic masses located in superior lateral orbits and underwent bilateral excisions of these without any postoperative complications.  相似文献   
8.
9.
Salmon calcitonin (SCT) is a well-tolerated peptide drug with a wide therapeutic margin and is administered parenterally for long-term treatments of bone diseases. Its clinical usefulness would be enhanced by the development of an orally active formulation. In this randomized crossover double-blinded phase I trial, controlled by both a placebo and a parenteral verum, we have tested a new oral formulation of SCT associated with a caprylic acid derivative as carrier. Eight healthy volunteers received single doses of 400, 800, and 1200 microg of SCT orally, a placebo, and a 10-microg (50 IU) SCT intravenous infusion. SCT was reliably absorbed from the oral formulation, with an absolute bioavailability of 0.5-1.4%, depending on the dose. It induced a marked, dose-dependent drop in blood and urine C-terminal telopeptide of type I collagen (CTX), a sensitive and specific bone resorption marker, with the effects of 1200 microg exceeding those of 10 microg intravenously. It also decreased blood calcium and phosphate, and increased the circulating levels of parathyroid hormone (PTH) and, transiently, the urinary excretion of calcium. It was well-tolerated, with some subjects presenting mild and transient nausea, abdominal cramps, diarrheic stools, and headaches. This study shows that oral delivery of SCT is feasible with reproducible absorption and systemic biological efficacy. Such an oral formulation could facilitate the use of SCT in the treatment of osteoporosis and other bone diseases.  相似文献   
10.
The cloning of cDNAs that encode functional glutamate receptors makes it possible to produce antibodies that can be used as high-affinity probes for the localization and characterization of these receptors in the mammalian brain. We have made antibodies to different regions of the first cloned member of this family, GluR1, using bacterially overproduced antigen. On Western blots, these antisera detect glycoprotein(s) of 105 kDa present in crude membranes of the hippocampus and cerebellum. The 105-kDa band is associated with postsynaptic densities, and it is observed in cultured cells upon transfection with the GluR1 cDNA. Although glutamate receptors are thought to be the most prevalent excitatory ligand-gated ion channel in the mammalian brain, immunohistochemistry reveals that the receptors recognized by these antisera are localized predominantly in neurons of the cerebellum and some structures of the limbic system, including the hippocampus, the central nucleus of the amygdala, and portions of the septum. This pattern of expression is, in general, consistent with the distribution of GluR1 mRNA as determined by in situ hybridization histochemistry. Our results suggest that glutamate excitatory circuits recognized by these antisera are predominantly found in regions of the limbic system that are reciprocally interconnected.  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