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   38379篇
  免费   2154篇
  国内免费   57篇
耳鼻咽喉   400篇
儿科学   1180篇
妇产科学   824篇
基础医学   5911篇
口腔科学   283篇
临床医学   3434篇
内科学   9197篇
皮肤病学   882篇
神经病学   3603篇
特种医学   1128篇
外国民族医学   31篇
外科学   4687篇
综合类   81篇
一般理论   6篇
预防医学   2742篇
眼科学   626篇
药学   2557篇
中国医学   74篇
肿瘤学   2944篇
  2023年   202篇
  2022年   131篇
  2021年   524篇
  2020年   314篇
  2019年   587篇
  2018年   1082篇
  2017年   769篇
  2016年   732篇
  2015年   911篇
  2014年   923篇
  2013年   1491篇
  2012年   2622篇
  2011年   2585篇
  2010年   1220篇
  2009年   967篇
  2008年   2383篇
  2007年   2457篇
  2006年   2322篇
  2005年   2386篇
  2004年   2320篇
  2003年   2112篇
  2002年   2058篇
  2001年   1056篇
  2000年   1131篇
  1999年   896篇
  1998年   187篇
  1997年   131篇
  1996年   137篇
  1995年   133篇
  1994年   110篇
  1992年   522篇
  1991年   464篇
  1990年   461篇
  1989年   431篇
  1988年   390篇
  1987年   378篇
  1986年   339篇
  1985年   319篇
  1984年   232篇
  1983年   179篇
  1982年   104篇
  1979年   157篇
  1974年   118篇
  1973年   106篇
  1972年   109篇
  1971年   114篇
  1970年   106篇
  1969年   129篇
  1968年   110篇
  1967年   103篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
Intraoperative coronary artery endarterectomy with excimer laser   总被引:1,自引:0,他引:1  
Compared with continuous-wave lasers, excimer lasers exhibit several in vitro advantages: nonthermal ablation process and linear relation between the number of pulses and the depth of the crater. A 308 nm, 20 nsec pulse duration, 1 to 5 repetition rate laser was specifically designed for clinical application. At the time of cardiopulmonary bypass in 10 symptomatic patients, before bypass grafting, a 1 mm diameter core specifically ultraviolet-tipped fiberoptic scope was introduced via the coronary arteriotomy and placed upstream (seven patients) and downstream (three patients) in contact with the stenosis. Laser power was increasingly delivered up to the clearing of the stenosis or occlusion. Quality of angioplasty was controlled by calibration of the neolumen, cardioplegic solution output through the laser-treated segment, and an eighth day or sixth month coronary arteriogram. In the first three patients studied on the eighth day, all laser-treated coronary artery segments showed an early parallel-linked patent neolumen despite competitive bypass graft flow. In the patients studied after 6 months, all recanalized segments were patent except one; in one patient the venous graft was occluded, but the upstream laser angioplasty was patent. The main limitation of the method lies in the fact that laser coronary recanalization is confined to the fiber core diameter. We conclude that (1) excimer laser angioplasty may be safe and efficient during surgical procedure and (2) as catheter flexibility remains the most critical problem, we are now assuming an appropriate tool with a multifiber system that is suitable for intraoperative as well as percutaneous routes.  相似文献   
42.
For experimental machine perfusion (MP) of the liver, the modified University of Wisconsin solution (UW-G) is most often used. In our search for an enriched MP preservation solution, Polysol was developed. Polysol is enriched with various amino acids, vitamins, and other nutrients for the liver metabolism. The aim of this study was to compare Polysol with UW-G for MP preservation of the liver. Rat livers were preserved during 24 hours with hypothermic MP using UW-G (n = 5) or Polysol (n = 5). Hepatocellular damage (aspartate aminotransferase [AST], alanine aminotransferase [ALT], lactate dehydrogenase [LDH], alpha-glutathione-S-transferase [alpha-GST]) and bile production were measured during 60 minutes of reperfusion (37 degrees C) with Krebs-Henseleit buffer. Control livers were reperfused after 24 hours of cold storage in UW (n = 5). MP using UW-G or Polysol showed less liver damage when compared with controls. Livers machine perfused with Polysol showed less enzyme release when compared to UW-G. Bile production was higher after MP using either UW-G or Polysol compared with controls. In conclusion, machine perfusion using Polysol results in better quality liver preservation than cold storage with UW and machine perfusion using UW-G.  相似文献   
43.
GOALS: 1) analyse the knowledge, attitudes and practices of Lome population about blood donation; 2) identify obstacles to blood donation among the population of Lome; 3) suggest some solutions to improve the performance of the National Blood Transfusion Centre (CNTS). METHODOLOGY: We have conducted a sample survey among the population of Lome from the 6th to 21st October 2003. Three hundred persons filled a questionnaire. RESULTS: In the sample, 183 (61%) were males. Their age ranged from 18 to 67 years with 2/3 of young peoples between 18 and 37 years. Pupils/students were 24,33%, wage-earners, 55% and the unemployed, 17,67%. More than the half of the investigated persons (54,67%) were unmarried and 96, 33% persons were literate. Nearly all the people (96,33%) knew about blood donation in Lome and they have received information mainly from friends, media and sensitization by the CNTS. Sixty-one percent of the investigated knew where blood is donated. All the investigated were unanimous about the vital role of blood. Whatever their religion, they recognized its sacred nature. The majority of the investigated (85%) were willing to donate blood. Only 95 people were donors. The reasons for non-donation were mainly related to the fear of catching diseases (31,71%) especially the HIV (9,76%), the lack of information (25,37%), the religious beliefs (19,51%) and the fear of knowing the result of one's HIV test. 277 people (92,33%) said that blood should be donated without remuneration. CONCLUSION: There is a growing interest in the blood donation among the population of Lome but new strategies must be elaborated to inform the population and motivate blood donors.  相似文献   
44.
Congenital cranial dysinnervation disorders (CCDDs) are responsible for 1–2% of infant strabismus cases. Insufficient innervation and misinnervation of aberrant nerve fibres lead to motility restrictions and synkinesis. We present the most common CCDDs and explain their pathogenesis and the resulting clinical features. Furthermore, we emphasize essential diagnostic steps and treatment aspects.  相似文献   
45.
A 24-year old woman displayed a coloboma of the right optic nerve with multiple small parapapillary retinochoroidal colobomas. This rare association makes one suspect that the pathogenesis of colobomatous defects of the optic disc area are caused by a faulty closure of the embryonic fissure and an abnormal maturation of the cells of the anlage of the optic nerve head.  相似文献   
46.
In a general review, the authors discuss present knowledge on the main protein on the surface of the normal fibroblast, fibronectin. The peculiarities of this glycoprotein (localisation at the level of the cell surface, importance of thiol groups in the structure and expression of certain of its properties, reduction of the cells transformed by oncogenic viruses) are considered. The relationships which they may present with a plasma protein, cold insoluble globulin, are discussed together with the important role which they seem to play in the phenomena of cell adhesiveness.  相似文献   
47.
The authors assess of three decades of struggle against Bancroftian filariasis in French Polynesia. Wuchereria bancrofti var. pacifica, aperiodic filaria, and Aedes polynesiensis, mosquito with high parasitologic output, set up a cycle very well adapted to the Polynesian environment; after numerous tests, the chemoprophylaxis with diethylcarbamazine (3 mg/kg/half-year) of all the exposed population has been decided, in association with methods of vector-control (use of predatory crustaceans). However, the achievement of this strategy is impeded by economical contingencies and the endemic comes up again particularly in areas close to eradication. Entomological clues show a high transmission over the greater part of French Polynesia.  相似文献   
48.
Twenty four patients who were hospitalized for a suspicion of spondylodiscitis were prospectively evaluated with magnetic resonance imaging (MRI), radiology and radionuclide studies. Fifteen patients had an infectious spondylodiscitis, four had a vertebral degenerative disease, four had a rheumaticus spondylodiscitis, one had a chemical spondylodiscitis. The microbiological examinations and the clinical development bore the diagnosis out. Seven patients underwent Indium 111 scanning. The results of this scanning were correlated with MRI results. The MRI was performed with a 0.35 T whole body superconducting unit using spin echo technique. All patients were studied in the sagittal plane with two pulse sequences and more often with a surface-coil: TR 500 msec./TE 28 msec. and TR 2,000 msec./TE 60 msec. In all cases of true infectious spondylodiscitis the MRI results finding were characteristics. On the image obtained with the TR 500 msec./TE 28 msec., there was a confluent decreased signal intensity from the vertebral bodies and the intervertebral disk space. On the image obtained with TR 2,000 msec./TE 60 msec. there was an increased signal intensity from the vertebral bodies and the intervertebral disk space. The other spondylodiscitis have given a different MRI imaging, it was a confluent decreased signal intensity from the vertebral bodies and the intervertebral disk space on the twice pulse sequences. different images were obtained during the evolution of the infectious: first we observed a modification of the vertebral signal then the typical image that we described then a normal signal of the vertebral bodies with a pathological signal from the intervertebral disk space at last a degenerative intervertebral disk.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
49.
5-Fluorouracil, 5-fluorouridine (FUrd), 5-fluoro-2'-deoxyuridine (FdUrd), 5-fluorocytidine (FCyd), 5-fluoro-2'-deoxycytidine (FdCyd), 5-trifluoro-2'-deoxythymidine (F3dThd), and the 5'-monophosphates and 3',5'-cyclic monophosphates thereof were found to inhibit thymidine kinase-deficient (TK-) mutant strains of herpes simplex virus (HSV) at a much lower concentration than the wild-type (TK+) HSV strains. Other 5-substituted 2'-deoxyuridines that have previously been recognized as potent thymidylate synthase inhibitors behaved in a similar fashion. The activity of FdUrd, FdCyd, F3dThd, and their 3',5'-cyclic monophosphates against TK-HSV was readily reversed by 2'-deoxythymidine (dThd) but not by 2'-deoxyuridine (dUrd). These compounds also inhibited the incorporation of [6-3H]dUrd into DNA at a concentration which was up to 5 orders of magnitude lower than the concentration at which the incorporation of [methyl-3H] dThd was inhibited. Thus, while not being a target for the well established anti-HSV compounds in TK+HSV-infected cells, thymidylate synthase appears to be an important target in TK-HSV-infected cells. In addition to dTMP synthase, TK-HSV-infected cells appear to reveal other therapeutically exploitable targets such as OMP decarboxylase (towards pyrazofurin), CTP synthase (towards carbodine and its cyclopentenyl analogue), dihydrofolate reductase (towards methotrexate), and S-adenosylhomocysteine hydrolase (towards neplanocins).  相似文献   
50.
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