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   48859篇
  免费   3278篇
  国内免费   188篇
耳鼻咽喉   524篇
儿科学   1231篇
妇产科学   858篇
基础医学   6394篇
口腔科学   1249篇
临床医学   4750篇
内科学   9959篇
皮肤病学   725篇
神经病学   4783篇
特种医学   2552篇
外国民族医学   6篇
外科学   7213篇
综合类   592篇
一般理论   40篇
预防医学   4027篇
眼科学   1199篇
药学   2929篇
中国医学   69篇
肿瘤学   3225篇
  2023年   204篇
  2022年   346篇
  2021年   809篇
  2020年   612篇
  2019年   810篇
  2018年   951篇
  2017年   773篇
  2016年   914篇
  2015年   1050篇
  2014年   1468篇
  2013年   2043篇
  2012年   3101篇
  2011年   3287篇
  2010年   1867篇
  2009年   1707篇
  2008年   3058篇
  2007年   3150篇
  2006年   3106篇
  2005年   3039篇
  2004年   2844篇
  2003年   2759篇
  2002年   2657篇
  2001年   614篇
  2000年   569篇
  1999年   635篇
  1998年   601篇
  1997年   468篇
  1996年   421篇
  1995年   402篇
  1994年   322篇
  1993年   292篇
  1992年   370篇
  1991年   338篇
  1990年   308篇
  1989年   325篇
  1988年   292篇
  1987年   310篇
  1986年   280篇
  1985年   300篇
  1984年   306篇
  1983年   293篇
  1982年   318篇
  1981年   297篇
  1980年   263篇
  1979年   225篇
  1978年   233篇
  1977年   195篇
  1976年   168篇
  1975年   177篇
  1974年   183篇
排序方式: 共有10000条查询结果,搜索用时 18 毫秒
111.
Nephritis occurs in 20%–50% of children with Henoch-Schönlein purpura (HSP), and the onset of renal involvement may be delayed for weeks or months in a substantial proportion of patients. The present study was performed to determine whether corticosteroid therapy was effective in preventing delayed nephritis in children with HSP. The medical records of 69 children with HSP were reviewed. Nineteen patients had acute nephritis occurring from 1–12 days after the onset of other signs and symptoms. The remaining 50 patients had no evidence of acute renal involvement. Of these 50 patients, 20 were treated during the acute phase of the illness with corticosteroids, while 30 never received corticosteroid therapy. Delayed nephritis (>3 weeks following an initial normal urinalysis) occurred in 4 of 20 (20%) patients who received prior corticosteroid treatment, and in 6 of 30 (20%) patients who were not treated. These results indicate that early corticosteroid therapy does not prevent delayed nephritis in children with HSP.  相似文献   
112.
Using a simplified procedure, we have extracted DNA from unstained paraffin sections of needle biopsies of kidney and liver transplants and identified the presence of CMV using the polymerase chain reaction. This method utilizes oligonucleotide primers for two genes shown to be specific for cytomegalovirus (CMV) as well as an internal control gene (hemoglobin) in a single reaction. Utilizing nested PCR amplification with agarose gel electrophoresis, CMV can be detected without radioisotopes to a level of sensitivity equivalent to one one-hundredth of a cytomegalic virocyte per cm2 of a 3-microM paraffin section. This method is applicable to situations where only scarce paraffin-embedded tissue is available.  相似文献   
113.
114.
The endogenous opioid system is implicated in excessive ethanol-drinking behavior. However, the role of individual opioid receptor subtypes in the mechanism underlying excessive ethanol-drinking behavior is not yet well understood. Therefore, we investigated the ability of a selective micro1-opioid antagonist, naloxonazine, to modulate ethanol-drinking behavior and ethanol discrimination in a rat model with the use of ethanol self-administration and drug discrimination paradigms. The effects of naloxonazine (0.001-10 mg/kg) on ethanol intake were examined in Sprague-Dawley rats under conditions of limited access to 10% (wt./vol.) ethanol and ad libitum access to food and water. Pretreatment with high doses of naloxonazine (1-10 mg/kg) significantly reduced ethanol consumption. When the effects of naloxonazine on food intake in free-feeding male rats were examined, naloxonazine (1.8-10 mg/kg) significantly suppressed 24-h food intake. Another group of rats was trained to discriminate ethanol (1.25 g/kg, i.p.) from saline on a fixed-ratio schedule (FR 10), and ethanol dose-response tests were conducted once rats had acquired ethanol-saline discrimination. Injections were given 15 min before ethanol dose-response tests were conducted, and after characterization of the ethanol dose-response curve, the effects of naloxonazine on ethanol discrimination were assessed by administering naloxonazine (0.001-10 mg/kg, i.p.) 15 min before ethanol administration. Treatment with naloxonazine (0.001-1.8 mg/kg, i.p.) before the ED(100) dose of ethanol partially antagonized the discriminative stimulus of ethanol without having any effect on the response rate. The results support the suggestion of involvement of micro1-opioid receptors in the discriminative effects of ethanol and ethanol-drinking behavior.  相似文献   
115.
The authors present the third installment of the guidelines and recommendations from the Safety Committee of the Society for Magnetic Resonance Imaging (now the Society of Magnetic Resonance) concerning various issues related to the safety and management of patients undergoing magnetic resonance (MR) procedures. This document was developed to provide standardized and consistent information for use by health practitioners involved in screening patients or other individuals for MR procedures.  相似文献   
116.
117.
A 21-year-old man was injured by a tailboard of a truck. He suffered a severe head injury with bilateral depressed skull fractures necessitating surgical decompression. On admission to the hospital the patient showed bending to pain stimuli (Glasgow Coma Score 5). Anisocoria was noticed from the beginning. Initial intracranial pressure (ICP), measured 3 hours after injury, was 30 mm Hg, and the cerebral perfusion pressure (CPP) was 70 mm Hg. During surgical elevation of the skull fracture on the right side an unexplainable rise of ICP to values of 100 mm Hg occurred, which corresponded to the mean arterial blood pressure (MAP). At the same time both pupils were dilated and fixed indicating a lack of cerebral perfusion. Due to immediate trephination of the opposite side, the ICP was lowered to values below 20 mm Hg, and sufficient cerebral perfusion (above 50 mm Hg) was regained. The patient showed a good recovery and was transferred to a rehabilitation center 5 weeks after injury.This case report emphasizes the importance of early and continuous intracranial pressure monitoring for adequate therapy in neurosurgical emergencies.  相似文献   
118.
119.
120.
Ex vivo testing techniques were used to determine the ferromagnetic qualities of, presence of heating in, and artifacts produced by 13 different heart valve prostheses exposed to a 1.5-T (64-MHz) magnetic resonance (MR) system. None of the heart valve prostheses showed a measurable deflection in the 1.5-T static magnetic field. Only minimal artifacts were produced during MR imaging with a fast spoiled GRASS (gradient-recalled acquisition in the steady state) pulse sequence. The largest temperature changes measured during a “worst case” MR imaging sequence (estimated average specific absorption rate, 2.5 W/kg; estimated spatial peak specific absorption rate, 7.6 W/kg) were +0.2°C with the implant imaged “in air” and +0.3°C with the implant imaged in normal saline. Therefore, MR procedures performed with a 1.5-T (64-MHz) MR system may be performed safely in patients with any of the 13 different heart valve prostheses evaluated in this study.  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