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   1177篇
  免费   43篇
  国内免费   4篇
耳鼻咽喉   7篇
儿科学   3篇
妇产科学   6篇
基础医学   128篇
口腔科学   8篇
临床医学   77篇
内科学   353篇
皮肤病学   7篇
神经病学   110篇
特种医学   104篇
外科学   196篇
综合类   3篇
预防医学   23篇
眼科学   3篇
药学   68篇
中国医学   8篇
肿瘤学   120篇
  2023年   8篇
  2022年   15篇
  2021年   28篇
  2020年   16篇
  2019年   17篇
  2018年   15篇
  2017年   21篇
  2016年   20篇
  2015年   16篇
  2014年   38篇
  2013年   48篇
  2012年   67篇
  2011年   89篇
  2010年   33篇
  2009年   42篇
  2008年   58篇
  2007年   81篇
  2006年   83篇
  2005年   84篇
  2004年   90篇
  2003年   64篇
  2002年   60篇
  2001年   23篇
  2000年   17篇
  1999年   16篇
  1998年   12篇
  1997年   12篇
  1996年   9篇
  1995年   9篇
  1994年   10篇
  1993年   15篇
  1992年   10篇
  1991年   23篇
  1990年   12篇
  1989年   7篇
  1988年   5篇
  1987年   5篇
  1986年   5篇
  1985年   4篇
  1984年   3篇
  1983年   3篇
  1979年   2篇
  1977年   2篇
  1976年   3篇
  1971年   3篇
  1969年   2篇
  1968年   3篇
  1963年   2篇
  1938年   2篇
  1935年   2篇
排序方式: 共有1224条查询结果,搜索用时 15 毫秒
11.
Nucleotide sequences and the deduced amino acid sequences of the gene encoding the matrix (M) protein of the Nishigahara and the CVS strains of rabies virus have been determined. The M gene is 609 nucleotides long and is capable of coding for a peptide composed of 202 amino acids. Sequence comparison of these M genes with those of other stains [Pasteur (PV), ERA, Avol] revealed that there is 89.7–91.5% homology at the nucleotide level, and 90.1–92.1% homology at amino acid level, between almost all combinations of these strains. However, in the combinations of the PV and ERA strains, and the virulent CVS and the avirulent CVS-derived Avol strains, much higher homology was observed both at the nucleotide and amino acid levels. The predicted secondary structure and hydropathy profiles also exhibited similar features. Recombinant vaccinia virus containing the M gene was constructed. Sodium dodecyl sulfate (NaDodSO4)-polyacrylamide gel electrophoresis of the precipitates obtained by immune reaction of the recombinant virus-infected cell lysate with a monoclonal antibody against the M protein revealed that electrophoretic mobility of the expressed protein is indistinguishable from that of the authentic M protein from rabies virions.The nucleotide sequence data of the M genes of the CVS and Nishigahara (RCEH) strains reported in this paper will appear in the DDBJ, EMBL, and GenBank Nucleotide Sequence Databases under the accession numbers D90450 and D90451.  相似文献   
12.
To learn the reasons for the high incidence of biliary carcinomain patients with anomalous arrangement of the pancreaticobiliaryduct (APBD) mutagenicity of the bile of APBD-modeled dogs thathad received a dorsal pancreatico-cholecystostomy was assayedby the Ames Salmonella mutation test. The bile from two outof 18 APBD dogs was mutagenic for Salmonella typhimurium strainTA98 under the condition of metabolic activation by rat liverS9 fraction, while the bile from 17 normal dogs was not mutagenic.Furthermore, the bile from five APBD dogs i.p. administered1-nitropyrene (1-NP), which is a typical environmental mutagen,was more mutagenic for strain TA98 than that from 1-NP-treatednormal dogs. The bile from the APBD dogs had very high amylaseactivity, indicating that the bile contained pancreatic juiceas a result of the pancreatico-cholecystostomy. When pancreaticjuice from a normal dog was added to the bile from 1-NP-treatednormal dogs, mutagenicity of the bile increased 1.6- to 2.0-fold.Furthermore, sulfatase increased the mutagenic activity of thebile in the presence of the pancreatic juice. HPLC revealedthat the bile from a 1-NP-treated APBD dog contained mutagenic1-nitro-6/8-hydroxypyrene and 1-nitro-3-hydroxypyrene, whilebile from a 1-NP-treated normal dog did not contain these deconjugatedproducts. The pancreatic juice from a normal dog had very high-glutamyltransferase (GGT) and aminopeptidase activities andlow sulfatase activity, but it had no ß-glucuronidaseactivity. In addition, the bacteria that easily infect the biliaryduct of APBD dogs, Escherichia coli, Klebsiella, Enterobacterand Proteus, had high ß-glucuronidase activity. Inparticular, Klebsiella showed a very high sulfatase activity.These results suggest that pancreatic juice enzymes and bacteriainfecting the biliary duct deconjugate the detoxified mutagensin the bile and induce mutagenicity of the bile from APBD dogsor APBD patients.  相似文献   
13.
Twenty-five patients who required mechanical ventilatory support (MVS) after major surgery or severe burns were studied to determine whether airway occlusion pressure (P0.1) is a clinically useful indicator to predict the success or failure of the weaning trial. A total of 33 weaning trials were attempted on these patients. Of the 33 trials, 24 were followed by successful weaning and 9 by failure. Although the success group, when compared with the failure group, had a lower respiratory rate (P 0.001), a lower minute ventilation (P 0.001), a higher maximal voluntary ventilation to minute ventilation ratio (P 0.01) and a higher forced vital capacity (P 0.05), no threshold values separated the success from the failure group. The alveolar-arterial PO 2 gradient, with an Fi O 2 of 1.0, in weaning success and failure showed no statistical difference. In contrast, all patients in the success group had a P0.1 of less than 3.5cmH2O and those in the failure group had a P0.1 of greater than 3.5cmH2O (P 0.001). We conclude that P0.1 is a clinically superior indicator for discontinuing MVS in patients with acute respiratory failure.(Okamoto K, Sato T, Morioka T: Airway occlusion pressure (P0.1)—A useful predictor for the weaning outcome in patients with acute respiratory failure—. J Anesth 4: 95–101, 1990)  相似文献   
14.
We evaluated the reliability of conventional weaning criteria from a ventilator during 33 weaning trials on 25 patients with acute respiratory failure (ARF). Of 13 criteria, a ratio of maximal voluntary ventilation to minute ventilation (MV) 2, a vital capacity 12ml·kg–1, a spontaneous respiratory rate 25 breaths·min–1, and a MV 10l·min–1 appeared to be useful for predicting successful weaning outcome. However, even using those criteria, there were many falsely-negative cases. The alveolar-arterial PO 2 gradient 350mmHg at an Fi O 2 1.0 was not useful as a predictor of weaning outcome. The present study demonstrates that conventional criteria are frequently inaccurate for predicting weaning outcomes and suggests that the use of some of these criteria may unnecessarily prolong the length of ventilator support. Since ventilation of most patients with poor oxygenation can be successfully discontinued by placing them on a continuous positive airway pressure system, these results suggest that the improvement of oxygenation is not an indispensable prerequisite for weaning from mechanical ventilators.(Okamoto K, Iwamasa H, Dogomori H, et al.: Evaluation of conventional weaning criteria in patients with acute respiratory failure. J Anesth 4: 213–218, 1990)  相似文献   
15.
Key words  airway management - difficult intubation - Hallermann-Streiff syndrome  相似文献   
16.
We investigated the biological effect of combining carbon-beam and X-ray in vitro. The results showed that when we employed Gray equivalent as the indication of therapeutic dose, the effects could be explained with simple additive way in the treatment plan. This fact provides important information about the combined therapy of carbon-beam and X-ray.  相似文献   
17.
18.
This retrospective study aimed to assess the diagnostic performance of contrast-enhanced ultrasound with Sonazoid (S-CEUS) for liver metastasis. We enrolled in this study 98 patients with 148 histologically proven liver lesions, with 121 metastases and 27 non-metastases. The S-CEUS technique showed sensitivity in 95.0% (115 of 121), specificity in 44.4% (12 of 27) and accuracy in 85.8% (127 of 148) for the diagnosis of metastasis. Higher body mass index had a negative influence on the positive predictive value and accuracy, and a greater depth of the lesion had a negative influence on the accuracy. The management was changed in 8 patients (8.2%) because of S-CEUS findings. In conclusion, the addition of S-CEUS may offer a great benefit by improvement of the quality of diagnosis and management for patients with cancer who have a tentative diagnosis of liver metastasis by contrast-enhanced computed tomography.  相似文献   
19.
20.
Summary A modified version of Brockenbrough's trans-septal catheterization technique was carried out in 11 patients indicated for percutaneous transvenous mitral commissurotomy (PTMC). In 8/11 (72.7%), a coiled guide-wire was successfully inserted through theforamen ovale without atrial septal puncture. The Brockenbrough needle was used merely to maintain stiffness and the orientation of the dilator. PTMC was performed with an Inoue single balloon without incident.Patent foramen ovale was found by transesophageal echocardiography prior to the operation in only 1/11 patients (9.0%); nonetheless, it proved not to be a critical factor for the success of the procedure. This procedure seems to have much potential to enable the treatment of mitral stenosis with a lowered risk to the patient, as long as it is performed with precision and caution.  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