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   59287篇
  免费   3540篇
  国内免费   183篇
耳鼻咽喉   585篇
儿科学   1724篇
妇产科学   1349篇
基础医学   9218篇
口腔科学   593篇
临床医学   5170篇
内科学   14529篇
皮肤病学   1399篇
神经病学   5849篇
特种医学   1609篇
外国民族医学   31篇
外科学   6554篇
综合类   159篇
一般理论   17篇
预防医学   4344篇
眼科学   1044篇
药学   4022篇
中国医学   123篇
肿瘤学   4691篇
  2023年   473篇
  2022年   746篇
  2021年   1490篇
  2020年   802篇
  2019年   1349篇
  2018年   1872篇
  2017年   1370篇
  2016年   1416篇
  2015年   1643篇
  2014年   1924篇
  2013年   2642篇
  2012年   4355篇
  2011年   4355篇
  2010年   2237篇
  2009年   1874篇
  2008年   3746篇
  2007年   3825篇
  2006年   3578篇
  2005年   3561篇
  2004年   3302篇
  2003年   3033篇
  2002年   2835篇
  2001年   1144篇
  2000年   1181篇
  1999年   1008篇
  1998年   329篇
  1997年   233篇
  1996年   215篇
  1995年   203篇
  1994年   154篇
  1993年   139篇
  1992年   554篇
  1991年   484篇
  1990年   481篇
  1989年   455篇
  1988年   407篇
  1987年   398篇
  1986年   356篇
  1985年   333篇
  1984年   238篇
  1983年   196篇
  1982年   117篇
  1979年   160篇
  1974年   125篇
  1973年   108篇
  1972年   112篇
  1971年   125篇
  1970年   109篇
  1969年   134篇
  1968年   114篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
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   
72.
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   
73.
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   
74.
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   
75.
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   
76.
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   
77.
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   
78.
PURPOSE: To measure accuracy of plus disease diagnosis by recognized experts in retinopathy of prematurity (ROP), and to conduct a pilot study examining performance of a computer-based image analysis system, Retinal Image multiScale Analysis (RISA). METHODS: Twenty-two ROP experts independently interpreted a set of 34 wide-angle retinal images for presence of plus disease. A reference standard diagnosis based on expert consensus was defined for each image. Images were analyzed by the computer-based system using individual and linear combinations of system parameters for arterioles and venules: integrated curvature (IC), diameter, and tortuosity index (TI). Sensitivity, specificity, and receiver operating characteristic areas under the curve (AUC) for plus disease diagnosis compared with the reference standard were determined for each expert, as well as for the computer-based system. RESULTS: Expert sensitivity ranged from 0.308 to 1.000, specificity ranged from 0.571 to 1.000, and AUC ranged from 0.784 to 1.000. Among individual computer system parameters, venular IC had highest AUC (0.853). Among all computer system parameters, the linear combination of arteriolar IC, arteriolar TI, venular IC, venular diameter, and venular TI had highest AUC (0.967), which was greater than that of 18 (81.8%) of 22 experts. CONCLUSIONS: Accuracy of ROP experts for plus disease diagnosis is imperfect. A computer-based image analysis system has potential to diagnose plus disease with high accuracy. Further research involving RISA system parameter cut-off values from this study are required to fully validate performance of this computer-based system compared with that of human experts.  相似文献   
79.
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   
80.
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