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   3506篇
  免费   204篇
  国内免费   43篇
耳鼻咽喉   58篇
儿科学   82篇
妇产科学   79篇
基础医学   355篇
口腔科学   70篇
临床医学   256篇
内科学   1105篇
皮肤病学   26篇
神经病学   314篇
特种医学   111篇
外科学   642篇
综合类   10篇
预防医学   73篇
眼科学   26篇
药学   172篇
中国医学   21篇
肿瘤学   353篇
  2024年   3篇
  2023年   25篇
  2022年   48篇
  2021年   98篇
  2020年   40篇
  2019年   56篇
  2018年   96篇
  2017年   71篇
  2016年   81篇
  2015年   103篇
  2014年   115篇
  2013年   153篇
  2012年   249篇
  2011年   243篇
  2010年   140篇
  2009年   121篇
  2008年   196篇
  2007年   237篇
  2006年   229篇
  2005年   224篇
  2004年   219篇
  2003年   217篇
  2002年   240篇
  2001年   47篇
  2000年   55篇
  1999年   33篇
  1998年   57篇
  1997年   46篇
  1996年   43篇
  1995年   44篇
  1994年   20篇
  1993年   27篇
  1992年   24篇
  1991年   22篇
  1990年   11篇
  1989年   10篇
  1988年   10篇
  1987年   10篇
  1986年   15篇
  1985年   18篇
  1984年   12篇
  1983年   4篇
  1982年   4篇
  1981年   4篇
  1980年   7篇
  1978年   5篇
  1977年   4篇
  1976年   3篇
  1975年   3篇
  1969年   2篇
排序方式: 共有3753条查询结果,搜索用时 15 毫秒
51.
52.
53.
Squalene is a type of oil obtained from shark liver. We describe a 76-year-old man diagnosed with chronic exogenous lipoid pneumonia due to squalene. A chest CT scan revealed pulmonary consolidation with ground-glass opacities in the right upper lobe. Positron emission tomography (PET) revealed significant uptake of 2-deoxy-2-F-fluoro-d-glucose (FDG) and 3'-deoxy-3'-F-fluorothymidine (FLT). Bronchoalveolar lavage (BAL) fluid contained many lipid-laden macrophages, and a transbronchial lung biopsy specimen showed clusters of foamy macrophages in alveolar spaces and granulomatous lesions. In addition, the presence of squalene in the BAL fluid was confirmed by gas chromatography-mass spectrometry, leading to a diagnosis of squalene-induced lipoid pneumonia. To the best of our knowledge, this is the first report of squalene-induced lipoid pneumonia in which squalene itself was successfully detected. This case also suggests the possibility that lipoid pneumonia shows significant uptake in FDG-PET and FLT-PET.  相似文献   
54.
A 30-year-old woman was admitted because of persistent and severe hemoptysis in November 2005. She had been given a diagnosis of interstitial pneumonia (IP) and pulmonary aspergilloma in 2001, and she was treated with oral prednisolone and itraconazole. However she had persistent and intractable hemoptysis. Multi-detector row computed tomography (MDCT) revealed that hemoptysis from the right upper lobe did not originate in bronchial arteries, but the abnormal branches of the right subclavian artery. Surgery was not performed because of her pulmonary function, but she was successfully treated by non-bronchial arterial coil embolization. At 10 months after the embolization, hemoptysis has not recurred. MDCT was very useful for diagnosing the cause of hemoptysis and selective nonbronchial arterial coil embolization might be helpful in treating intractable or refractory hemoptysis.  相似文献   
55.

Background

Central line-associated bloodstream infections (CLABSIs) are among the most serious complications especially in blood cancer patients. In January 2013, Centers for Disease and Prevention (CDC) introduced a new surveillance definition of mucosal barrier injury-associated laboratory-confirmed bloodstream infection (MBI-LCBI). This study was to determine the impact of MBI-LCBI on CLABSIs and compare the clinical characteristics of MBI versus non-MBI-LCBI cases.

Patients and methods

We retrospectively reviewed the records of 250 consecutive patients. They were admitted in department of hematology at Aichi Medical University Hospital. We applied the revised 2013 CLABSI surveillance protocol to all CLABSI cases identified during the 47-months period from May 2012 through June 2016.

Results

A total of 44 CLABSIs were identified. The median patient age was 65 years (range, 12 to 89). Among 44 patients, 31 patients were diagnosed as leukemia (70.5%) and 12 patients as lymphoma (27.3%). Six patients underwent bone transplantation for leukemia or myelodysplastic syndrome (13.6%). A total of 20 patients (45.5%) were classified as MBI-LCBI and 24 (54.5%) were classified as non-MBI-LCBI. The primary disease type (P = 0.018), neutropenic within 3 days before CLABSI (MBI-LCBI vs. non-MBI-LCBI: 95.0% vs. 26.3%, P = <0.0001), line(s) removed owing to CLABSI (15.0% vs. 54.2%, P = 0.011) and Gram-negative organisms cultured (70.0% vs. 37.5%, P = 0.004) showed significantly difference between the groups.

Conclusion

Our data showed that MBI-LCBI cases account for 45.5% of the CLABSI cases identified in blood cancer patients, and constituted a significant burden to this high-risk patient population.  相似文献   
56.
A 70-year-old woman with situs inversus totalis underwent catheter ablation for atrial fibrillation and atrial flutter. Although her morphologic left atrium (LA) was enlarged, we performed cryoballoon ablation and liner radiofrequency ablation of the cava-tricuspid isthmus without mapping atrial arrhythmias. However, a different form of atrial tachycardia (AT) recurred. We performed catheter ablation a second time using a three-dimensional electroanatomic mapping system. AT was not terminated by the liner ablation at the roof of morphologic LA and mitral isthmus but sustained by changing the atrial activation sequence and cycle length. Multipolar mapping catheter revealed that fractionated low-amplitude potentials were densely located in a limited area of the anterior morphologic LA, and an activation map demonstrated the presence of small-circuit reentry with an extremely slow conduction at the anterior morphologic LA. A single energy application targeting the fragmented potentials successfully terminated the AT. We successfully treated multiple ATs with a complex anatomy using a three-dimensional electroanatomic mapping system.  相似文献   
57.
We herein report a 65-year-old man with progressive multifocal leukoencephalopathy (PML) after 2-year remission from acute myeloid leukemia who developed recurrent episodes of left hemiparesis with gadolinium enhancement on magnetic resonance imaging. Steroid pulse therapy for each exacerbation induced clinical and radiological improvement, suggesting that exacerbations are an excessive immune response to the JC virus and distinct from immune reconstitution inflammatory syndrome (IRIS). Although glucocorticoids are recommended only for IRIS, steroid pulse therapy should be considered as a therapeutic option in cases of exacerbation of hematologic malignancy-associated PML. Importantly, neuroimaging is not sufficient to differentiate excessive inflammation from a controlled inflammatory response, for which steroids are not recommended.  相似文献   
58.
Ethanol exerts damaging effects on gastric mucosa and delays ulcer healing. To investigate the effect of ethanol on the wound repairing process, we used a wound repair model using primary cultured gastric mucosal cells. A confluent monolayer gastric mucosal cell sheet consisting mainly of mucous cells was wounded to make a cell-free area of constant size. Cell-free area was restored with time after wounding and monitored every 12 hr using a computer image analyzer to observe epithelial cell restoration quantitatively in the presence and absence of ethanol (2.0%). It was found that, although the control wound was completely repaired in 36 to 48 hr, the group treated with 2.0% ethanol showed a significant delay of repair. In the control, 5-bromodeoxyuridine-positive cells appeared around the wound in 24 to 36 hr. In contrast, the group treated with 2.0% ethanol showed no 5-bromodeoxyuridine-positive cells during the experiment. In conclusion, 2.0% ethanol retarded the repair of gastric mucosal restoration by inhibiting the initial gastric cell migration, followed by inhibition of proliferation of cells.  相似文献   
59.
A 76-year-old male patient with jaundice was diagnosed as having hepatic hilar cholangiocarcinoma. The patient underwent percutaneous transhepatic biliary drainage of the left and the right intrahepatic bile duct. He could not have a percutaneous transhepatic endoprosthesis placed because it was impossible to pass the guidewire through the stenotic portion of the lesion. The patient was operated, but the tumor was considered to be unresectable. Along the intrahepatic routes formed by the preexisting two percutaneous transhepatic biliary drainage tubes, silicon tubes were inserted. Through the lumen of a long jejunal limb, Roux-en-Y, the tubes with five to six side holes were passed in the distal direction and drawn out from the lumen of the jejunal limb and passed through the abdominal wall to outside. The tubes were occluded and buried in the subcutaneous space after a few clamping tests. He died of liver failure in his house four months after the operation without any symptoms of jaundice, fever or of obstruction of the tubes.  相似文献   
60.
BACKGROUND AND AIM: Usually, bacteria are cryopreserved for short-term storage at low and ultra-low temperatures. There are no reports as to whether Helicobacter pylori is a fragile bacteria when stored at low and ultra-low temperatures as compared with other intestinal bacteria. A study was done on seven H. pylori strains and other intestinal bacteria to compare different temperatures for storage of organisms in saline solution. METHODS: Seven H. pylori strains, specifically American Type Culture Collection (ATCC) strains 43504 and TN2GF4, and five strains isolated from the present patients were grown on a modified Skirrow's agar for H. pylori. Escherichia coli and Bacteroides distasonis, both representing isolates from the present patients, were grown on trypticase soy blood agar for E. coli, and EG agar for B. distasonis. Culture was for 4-5 days under microaerobic, aerobic and anaerobic conditions at 37 degrees C. Cells were harvested by scraping growth from the solid medium and into sterile saline. The cells were adjusted to concentrations of 109 viable cells/mL in saline and preserved at 4 degrees C, -20 degrees C, or -80 degrees C for 3 weeks before reculture under microaerobic, aerobic and anaerobic conditions at 37 degrees C for 7 days. After incubation, morphologically distinct colonies were counted, isolated, and identified by standard bacteriologic techniques. The H. pylori were morphologically analyzed by electronic microscopy before and after preservation. Mongolian gerbils were inoculated with the cryopreserved H. pylori to evaluate the bacterial infectivity. RESULTS: Six of the seven H. pylori strains failed to culture after being preserved at 4 degrees C, -20 degrees C, or -80 degrees C. Only ATCC 43504 could be cultured after freezing at -80 degrees C. The number of H. pylori ATCC 43504 before preservation was 9.0 +/- 0.5 (log10 no. organisms/mL) and decreased to 5.7 +/- 0.6 after preservation. Morphologically, all H. pylori except ATCC 43504 strains transformed from a bacillary to a coccoid form after preservation. In addition, none of the H. pylori strains could infect Mongolian gerbils after preservation. Escherichia coli and B. distasonis were recovered. Titers before and after 4 degrees C, -20 degrees C, and -80 degrees C, respectively, were 9.1 +/- 0.2, 8.9 +/- 0.5, 8.6 +/- 0.3, and 8.7 +/- 0.3 for E. coli and 9.1 +/- 0.4, 8.7 +/- 0.6, 8.6 +/- 0.5, and 8.8 +/- 0.3 for B. distasonis. CONCLUSIONS: Helicobacter pylori is a fragile bacteria for storage at low and ultra-low temperatures in comparison with other intestinal bacteria.  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