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   5751篇
  免费   341篇
  国内免费   23篇
耳鼻咽喉   35篇
儿科学   170篇
妇产科学   167篇
基础医学   674篇
口腔科学   85篇
临床医学   552篇
内科学   1260篇
皮肤病学   63篇
神经病学   384篇
特种医学   458篇
外科学   890篇
综合类   115篇
预防医学   361篇
眼科学   197篇
药学   432篇
  1篇
中国医学   27篇
肿瘤学   244篇
  2022年   54篇
  2021年   84篇
  2020年   59篇
  2019年   69篇
  2018年   88篇
  2017年   70篇
  2016年   72篇
  2015年   119篇
  2014年   151篇
  2013年   172篇
  2012年   267篇
  2011年   284篇
  2010年   157篇
  2009年   168篇
  2008年   213篇
  2007年   259篇
  2006年   240篇
  2005年   241篇
  2004年   240篇
  2003年   215篇
  2002年   205篇
  2001年   163篇
  2000年   196篇
  1999年   145篇
  1998年   63篇
  1997年   50篇
  1996年   50篇
  1995年   59篇
  1994年   57篇
  1993年   51篇
  1992年   119篇
  1991年   79篇
  1990年   102篇
  1989年   106篇
  1988年   121篇
  1987年   97篇
  1986年   71篇
  1985年   103篇
  1984年   66篇
  1983年   80篇
  1981年   49篇
  1979年   51篇
  1978年   53篇
  1977年   44篇
  1975年   48篇
  1974年   64篇
  1972年   55篇
  1971年   50篇
  1970年   40篇
  1967年   40篇
排序方式: 共有6115条查询结果,搜索用时 15 毫秒
61.
摘要目的建立测定维吾尔医药阿米乐努西达日蜜膏没食子酸含量的方法。方法采用高效液相色谱法,色谱柱:phenomenex C18(4.6 mm×250 mm,5 μm);检测波长:273 nm;流动相:甲醇 0.4%磷酸水溶液(10:90);流速:1.0 mL•min-1;进样量:10 μL;柱温:25 ℃。结果没食子酸在0.106~0.530 μg范围内峰面积与进样量具有良好的线性关系(r=0.999 7),平均加样回收率为97.9%(n=9),RSD=1.13%。结论该方法操作简便、准确、灵敏度高、重复性好,可为阿米乐努西达日蜜膏质量评价提供参考。  相似文献   
62.
63.
1. The quantitative method for the estimation of agglutinins has been applied to antimeningococcal horse, rabbit, and chicken sera and to the sera of humans convalescing from meningococcus meningitis. The type-specific and group-specific agglutinin N can be measured, using homologous and heterologous suspensions of meningococci. 2. Type I horse, rabbit, and chicken antimeningococcal sera contain considerable amounts of antibody which cannot be removed either by Type II meningococcus suspension or by preparations of the Type I specific polysaccharide. This residual type-specific antibody has marked potency in protecting mice against subsequent infection with meningococci. 3. Most human convalescent sera contain group-specific antibody. Small amounts of protective antibody and of antipolysaccharide are also formed. 4. Type I antisera absorbed with Type I polysaccharide and with Type II meningococci could be used as a guide in the purification of this new antigen.  相似文献   
64.
65.
Infections are an uncommon cause of chronic diarrhoea. Parasites are most likely, including protozoa like giardia, cryptosporidia and cyclospora. Bacteria are unlikely to cause chronic diarrhoea in immunocompetent individuals with the possible exception of Yersinia, Plesiomonas and Aeromonas. Infectious diarrhoea can trigger other causes of chronic diarrhoea, including inflammatory bowel disease, irritable bowel syndrome and “Brainerd-type” diarrhoea. A thorough evaluation should detect most infections causing chronic diarrhoea.  相似文献   
66.
67.
Pandemic influenza A (H1N1) virus infection is rapidly spreading and has also become a common problem in Germany. Many cases with severe clinical presentation and death have been documented, especially in persons with underlying medical conditions. As of December 15, 2009, Germany has reported 119 H1N1-associated deaths. We report here the first H1N1-associated death in Germany, a 36-year-old woman with morbid obesity. The patient underwent a laparotomy with colon resection due to colon ischemia, a rare visceral complication in such cases. In this article an attempt has been made to reflect the state of requirements in terms of safety, occupational health, hygiene and working conditions with respect to activities involving logistics in the diagnostics, treatment (also surgical) and handling of such patients. Given the rapidly evolving nature the outbreak of human infection with the novel influenza A (H1N1) virus, influenza vaccination is recommended as the only way to prevent the infection of health care workers and patients with underlying medical conditions.  相似文献   
68.
The purpose of this study was to evaluate a dual head coincidence gamma camera (DH-PET) equipped with single-photon transmission for 2-[fluorine-18]-fluoro-2-deoxy-d-glucose (FDG) imaging in oncological patients. Forty-five patients with known or suspected malignancies, scheduled for a positron emission tomography (PET) scan, were first studied with a dedicated ring PET and subsequently with DH-PET. All patients underwent measured attenuation correction using germanium-68 rod sources for ring PET and caesium-137 sources for DH-PET. Ring PET emission scan was started 64±17 min after intravenous administration of 235±42 MBq FDG. DH-PET emission followed 160±32 min after i.v. FDG. Attenuation-corrected and non-attenuation-corrected images were reconstructed for ring PET and DH-PET. The image sets were evaluated independently by three observers blinded to clinical data and to results of conventional imaging. Attenuation-corrected ring PET as the standard of reference depicted 118 lesions, non-attenuation-corrected ring PET 113 (96%) lesions, and attenuation-corrected DH-PET and non-attenuation-corrected DH-PET, 101 (86%) and 84 (71%) lesions, respectively (P<0.05). The lesion detection rate of attenuation-corrected and non-attenuation-corrected DH-PET was almost similar for lesions >20 mm, whereas attenuation correction increased the detection rate from 60% to 80% for lesions ≤20 mm (P<0.01). A patient-based analysis revealed concordant results relative to attenuation-corrected ring PET for non-attenuation-corrected ring PET, attenuation-corrected DH-PET and non-attenuation-corrected DH-PET in 42 (93%), 36 (80%) and 31 (69%) patients, respectively. Differences might have influenced patient management in two (4%), six (13%) and ten (22%) patients, respectively. In conclusion, measured attenuation correction markedly improves the lesion detection capability of DH-PET. With measured attenuation correction the diagnostic performance of DH-PET is closer to that of dedicated ring PET. Received 9 April and in revised form 20 April 1999  相似文献   
69.
OBJECTIVE: The aim of our study was to evaluate contrast-enhanced sonography as an alternative to radiographic voiding cystourethrography in the detection of vesicoureteral reflux. SUBJECTS AND METHODS: A total of 46 children, ranging in age from 3 weeks to 14 years (median: 4 years, 6 months) with 92 ureterorenal units were investigated for reflux using radiographic voiding cystourethrography and contrast-enhanced sonography in one session. After sonography of the urinary tract, the bladder was filled with saline solution via a catheter. Later, a contrast-enhancing agent was instilled and sonography was repeated. Documentation was done using S-VHS video and a laser camera. Reflux was diagnosed when microbubbles were observed in the ureter or in the renal pelvis. In addition, conventional voiding cystourethrography was performed. Patients without micturition during either sonography or radiographic examination were excluded (eight ureterorenal units). RESULTS: The findings obtained by contrast-enhanced sonography and voiding cystourethrography were concordant in 78 ureterorenal units (92.9%). No reflux was detected in 67 units (79.8%) by either method. With voiding cystourethrography as the standard of reference, the sensitivity of contrast-enhanced sonography was 91.7%; the specificity, 93.1%; and the accuracy, 92.9%. The positive predictive value was 68.8%, and the negative predictive value was 98.5%. CONCLUSION: Contrast-enhanced sonography is highly sensitive for the detection of vesicoureteral reflux. Therefore, it may reduce the number of radiographic investigations.  相似文献   
70.
大鼠原位肝脏低温灌注和复流模型的建立及意义   总被引:8,自引:0,他引:8  
目的建立一种大鼠肝脏原位低温灌注再复流模型,用于离体及活体供肝肝切除术的研究。方法大鼠78只,分成4组,A、B组分别用乳酸林格氏液和自制灌注液灌注,C组仅行全肝血流阻断,D组作正常对照。脾静脉和右肾上腺静脉分别作为灌注液流入和流出道,行在体原位低温灌注,观察再复流后对肝细胞和肝窦内皮细胞的影响。结果C组再复流2h和6h血清透明质酸浓度为(250.0±24.1)μg/L、(290.4±37.0)μg/L,分别高于A组(142.9±30.1)μg/L、(200.0±17.5)μg/L,差异均有非常显著性(P<0.01);B组浓度为(63.3±16.2)μg/L、(62.1±14.6)μg/L,与A组相比浓度更低(P<0.01)。结论该模型方法简单,易成功,可用于离体和活体供肝肝切除防止肝脏损伤的研究。  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