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   29815篇
  免费   1408篇
  国内免费   256篇
耳鼻咽喉   343篇
儿科学   621篇
妇产科学   359篇
基础医学   3695篇
口腔科学   608篇
临床医学   1921篇
内科学   8131篇
皮肤病学   531篇
神经病学   2395篇
特种医学   1135篇
外科学   5074篇
综合类   128篇
一般理论   1篇
预防医学   798篇
眼科学   654篇
药学   1777篇
中国医学   63篇
肿瘤学   3245篇
  2023年   208篇
  2022年   436篇
  2021年   752篇
  2020年   379篇
  2019年   496篇
  2018年   707篇
  2017年   555篇
  2016年   658篇
  2015年   691篇
  2014年   815篇
  2013年   1020篇
  2012年   1650篇
  2011年   1919篇
  2010年   1186篇
  2009年   987篇
  2008年   1654篇
  2007年   1754篇
  2006年   1791篇
  2005年   1780篇
  2004年   1778篇
  2003年   1636篇
  2002年   1616篇
  2001年   564篇
  2000年   458篇
  1999年   530篇
  1998年   386篇
  1997年   313篇
  1996年   256篇
  1995年   237篇
  1994年   208篇
  1993年   219篇
  1992年   366篇
  1991年   311篇
  1990年   254篇
  1989年   298篇
  1988年   236篇
  1987年   264篇
  1986年   232篇
  1985年   228篇
  1984年   181篇
  1983年   156篇
  1982年   81篇
  1981年   84篇
  1979年   134篇
  1978年   84篇
  1975年   74篇
  1974年   80篇
  1970年   79篇
  1969年   67篇
  1968年   70篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Electron microscopy and bacteriological culture revealed viable bacteria covered with a glycocalyx (biofilm) in choledochal stones recovered from two patients with acute cholangitis. On the cut surface of the choledochal stones, the cholesterol stone component was surrounded with a layer of brown pigment stone. In each case, bacterial culture of the choledochal stone recoveredPseudomonas aeruginosa. Since alginate is the main component of the glycocalyx produced byP. aeruginosa, serum IgM, IgG and IgA anti-alginate antibodies were measured in each patient. The present study is the first to demonstrate acute and transient IgM seroconversion to alginate in cases of acute cholangitis. In one case, the elevation of anti-alginate IgM preceded the elevation of anti-alginate IgG. The authors propose that the bacterial glycocalyx may play a significant role in acute cholangitis.  相似文献   
102.
103.
Purpose As the middle-ear cavity is one of the noncompliant gas-filled cavities, an increase in middle-ear pressure (MEP) instead of volume expansion is observed with inhalation of nitrous oxide (N2O). Changes in MEP cause many complications, such as ear pain, temporary hearing impairment, and postoperative emesis. Therefore, we investigated changes in MEP during total intravenous anesthesia (TIVA) with propofol, fentanyl, and ketamine (PFK) and inhalation of N2O. Methods Twelve patients were anesthetized with PFK until 60 min after the induction of anesthesia, and then N2O (60%) inhalation was started. MEP was measured by impedance audiometry (ranging from −300 daPa to +200 daPa) at 10-min intervals during PFK, and at 2-min intervals after the inhalation of N2O. Results MEP gradually but significantly increased from the preanesthetic value of 16±8 to 34±12 (SEM) daPa 50 min after the induction of PFK. However, MEP did not exceed the normal limit. The values of MEP in all patients were more than 200 daPa within 36 min after the start of inhalation of N2O in oxygen. Conclusion PFK had a minimal effect on MEP, whereas addition of N2O to PFK increased MEP dramatically. Therefore, TIVA, or at least PFK, would be a better choice for patients with middle-ear or upper-airway diseases.  相似文献   
104.
The results of treating 12 consecutive patients with unresectable colorectal hepatic metastases with a hepatic arterial infusion of high-dose Adriamycin, 100–120 mg/m2, using hepatic venous isolation (HVI) and charcoal hemoperfusion (CHP) are reported herein. Adriamycin was administered over 5–15 min under extracorporeal drug elimination by HVI-CHP. HVI was percutaneously accomplished by either the double-balloon technique using a Fogarty occlusion catheter (8/22F) or a balloon-tipped catheter (16F). During the infusion, isolated hepatic venous blood was filtered by CHP and pumped into the left axillary vein. There were no lethal complications, and good hemodynamic tolerance to HVI-CHP was confirmed. Tumor liquefaction accompanied by a sharp decrease in serum carcinoembryonic antigen levels by more than 50% of pretreatment levels was observed in 6 of the 12 patients 1 month after treatment. Apart from chemical hepatitis, which developed in 11 (92%) of the patients, the Adriamycin toxicities were well controlled following the development of nausea and vomiting in 2 patients (17%), leukopenia <2,000/mm3 in 3 (25%), and gastric ulcer in 1 (8%). These results indicate that this method is a safe and useful procedure for otherwise hazardous high-dose intraarterial chemotherapy in patients with unresectable hepatic tumors.  相似文献   
105.
A case of renal angiomyolipoma with bone formation is reported. A 61-year-old woman was admitted to our hospital with one month history of fever. About 15 cm in diameter mass was palpated in her right lower abdomen. Plain abdominal roentgenography, ultrasonography and computed tomography showed marked calcification in the cephalic portion of the right kidney, tumors surrounding right kidney and another tumor in the right lower abdomen. All these tumors and the kidney constituted a big mass continuously, and no fatty component was demonstrated. Total excision of the mass including the kidney was performed. The mass was 30 X 24 X 10 cm in size and 3,240 g in weight. Histologically, the tumor was compatible to renal angiomyolipoma. But, radiopaque shadows which looked like calcification were disclosed to be bones, and fatty tissues were not seen so much. Therefore, the name "benign mesenchymoma" was thought to be more acceptable than angiomyolipoma in this case. Preoperative diagnosis of renal angiomyolipoma is the demonstration of fatty densities in the tumor, and the characteristic extrarenal development should also be taken into consideration. Furthermore, the bone formation of angiomyolipoma, which is very rare might be an important finding to angiomyolipoma.  相似文献   
106.
It has been reported that the two types of muscarinic receptors, "M1" and "M2", exist in the opossum lower esophageal sphincter. The presence of these muscarinic receptor subtypes had been confirmed with the discovery of the M1 selective antagonist, pirenzepine. But little is known about muscarinic receptor subtypes in gastric smooth muscle. The aim of this study was to identify the muscarinic receptor subtypes on the gastric smooth muscle responsible for the contraction of rat gastric muscle strip. Also, we examined the mechanism of the action of aclatonium napadisilate on rat gastric smooth muscle in vitro. The stimulation of M2 receptor caused the contraction of the gastric smooth muscle. McN-A-343, selective M1 agonist, caused weak contraction of the gastric smooth muscle, and this response was not affected by the selective M1 antagonist, pirenzepine. Aclatonium napadisilate stimulated M2 receptor and caused the gastric smooth muscle contraction. We conclude that the contraction of the gastric smooth muscle is caused by the stimulation of the M2 receptor and this reaction was not affected by tetrodotoxin, suggesting the M2 receptor is located directly on the gastric smooth muscle. The weak contraction of the gastric smooth muscle caused by McN-A-343 was not affected by the selective M1 antagonist, pirenzepine, suggesting that McN-A-343 may not be a pure M1 selective agonist. The action of aclatonium napadisilate is supposed to stimulate the M2 receptor.  相似文献   
107.
Cardiovascular depression occuring when diazepam is combined with fentanyl has been investigated using the benzodiazepine antagonist RO15-1788 in the dog.After the initial administration of fentanyl (40mcg/kg), the mean arterial pressure (MAP) decreased to 89% of its control value. Following the administration of diazepam (1.2mg/kg), the MAP and the total peripheral resistance (TPR) decreased significantly, to 75% and 83% of their control values respectively. After the administration of RO15-1788 (0.4mg/kg), the MAP increased significantly to 90% and the TPR to 102% of their control values and, lastly, the administration of naloxone (40mcg/kg) increased the MAP to 108% of its control value. No relationship was found between the changes in the catecholamines and the changes in the MAP after the administration of fentanyl, diazepam, and RO15-1788.The mechanism of circulatory depression when diazepam was used with fentanyl is interpreted as being a peripheral vasodilatory effect of diazepam acting by way of the benzodiazepine receptors since RO15-1788 was found to antagonize this effect.(Sone T, Kato T, Tsukahara I et al.: The effect of RO15-1788 on cardiovascular depression caused by fentanyl and diazepam. J Anesth 2: 69–76, 1988)  相似文献   
108.
Summary This report presents a variant of Gerstmann-Sträussler syndrome (GSS). A 53-year-old female had developed slowly progressive dementia and atactic gait since the age of 45. No myoclonic jerks and periodic synchronous discharges were observed throughout the illness. The neuropathological study revealed that many amyloid plaques and widespread Alzheimer's neurofibrillary tangles (NFTs) appeared in the cerebral cortex. Characteristically, the plaques reacted with anti-prion protein and none of them reacted with anti- protein, and they were made of many components, including amyloid cores, macrophages laden with lipid granules and/or degenerated neurites. Neuropil threads were seen mainly in amyloid plaques. Moreover, plaques appeared which were confluent and laminar in arrangement in the fifth and sixth cortical layers and had a close relationship to the neuronal loss. There was no spongiform change in the cerebral cortex or cerebellum. The cerebellum was almost intact except for a few amyloid plaques. Ultrastructurally, some of the plaques simulated kuru plaques and others had many degenerated neurites possessing paired helical filaments and other accumulated organelles. GSS has been proposed to include cases with progressive ataxia, dementia and massive multifocal plaques in the brain with or without cerebral spongiform changes. The case presented here is a very peculiar case of GSS. Recently, similar cases have been reported in some large families, diagnosed as familial Alzheimer's disease. These cases may be a telencephalic form with numerous NFTs of GSS.  相似文献   
109.
Positron emission tomography (PET) studies on regional cerebral glucose metabolism and [18F]fluorodopa uptake were performed on 3 patients with "pure akinesia without rigidity and tremors", 3 progressive supranuclear palsy (PSP) patients, and 5 patients with Parkinson's disease. The "pure akinesia" and PSP patients showed a marked decrease in glucose metabolism in the frontal cortex and striatum, and a decreased uptake of [18F]fluorodopa in the striatum. While the Parkinson's disease patients had a decreased uptake of [18F]fluorodopa in the striatum but no abnormality in the glucose metabolism. Magnetic resonance imaging (MRI) showed atrophy of the pretectum and dorsal pons in "pure akinesia" and PSP patients, but there was no such abnormality in the Parkinson's disease patients. As described above, patients with "pure akinesia" and PSP patients revealed similar findings on PET and MRI studies, while Parkinson's disease patients showed substantially different results.  相似文献   
110.
Two patients with "my hand" sign in association with tactile extinction from callosal lesion, one due to left anterior cerebral artery occlusion, the other due to right anterior cerebral artery aneurysm rupture, were reported. The examination of "my hand" sign was performed with the methods proposed by Brion et al. Our patients correctly responded when they grasped their own or the examiner's thumb with their left hand. But they replied "my finger"when they grasped not only their own but also the examiner's thumb with their right hand. Left tactile extinction was observed after a routine extinction test in one patient, and it was observed in the other after the following method: both patient's index fingers were disposed in his midline position. In these methods of extinction test, they made errors in saying "right" when both fingers were touched simultaneously. However, they said "both" when their right index finger alone was touched (synchiria) during an extinction test using the following method: both index fingers of patients were approached by examiner to touch each other or for one of them to touch the examiner's finger. When they were asked whose finger they touched in this method (whose finger test), they made the same errors as seen in "my hand" sign test. These test results suggest that there is a common underlying mechanism in the "my hand" sign and extinction, because the sense of double stimulations felt when only one stimulation is given (synchiria), is a possible explanation for the "my hand" sign and the pathogenesis of synchiria appears to be related to extinction.(ABSTRACT TRUNCATED AT 250 WORDS)  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