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   804篇
  免费   46篇
  国内免费   7篇
耳鼻咽喉   1篇
儿科学   28篇
妇产科学   8篇
基础医学   80篇
口腔科学   9篇
临床医学   92篇
内科学   153篇
皮肤病学   6篇
神经病学   65篇
特种医学   190篇
外科学   80篇
综合类   7篇
一般理论   1篇
预防医学   29篇
眼科学   6篇
药学   75篇
肿瘤学   27篇
  2023年   2篇
  2022年   4篇
  2021年   14篇
  2020年   4篇
  2019年   11篇
  2018年   19篇
  2017年   9篇
  2016年   16篇
  2015年   23篇
  2014年   16篇
  2013年   31篇
  2012年   43篇
  2011年   29篇
  2010年   27篇
  2009年   32篇
  2008年   30篇
  2007年   30篇
  2006年   24篇
  2005年   25篇
  2004年   27篇
  2003年   22篇
  2002年   29篇
  2001年   24篇
  2000年   16篇
  1999年   17篇
  1998年   28篇
  1997年   30篇
  1996年   36篇
  1995年   29篇
  1994年   27篇
  1993年   20篇
  1992年   16篇
  1991年   8篇
  1990年   12篇
  1989年   21篇
  1988年   17篇
  1987年   15篇
  1986年   10篇
  1985年   7篇
  1984年   4篇
  1983年   6篇
  1982年   5篇
  1981年   9篇
  1980年   7篇
  1979年   4篇
  1978年   2篇
  1977年   4篇
  1976年   10篇
  1975年   3篇
  1965年   1篇
排序方式: 共有857条查询结果,搜索用时 15 毫秒
41.
Roxatidine acetate, a new H2 receptor antagonist, was compared with ranitidine in the treatment of duodenal ulcers in a double-blind multicentre study. Eighty-four patients with endoscopically proven duodenal ulcer were randomized to receive 150 mg roxatidine acetate or 300 mg ranitidine at bedtime. Repeat endoscopy was performed after 4 weeks (25–33 days) and if the ulcer had not healed, another endoscopy was performed after a further 4 weeks of treatment. Using per protocol analysis 73.6% of ulcers treated with roxatidine healed at 4 weeks compared to 72.2% of ulcers treated with ranitidine (P=NS). The healing rates at 8 weeks were 92% with roxatidine and 83.3% with ranitidine (P=NS). Using equivalence tests, the healing rate of roxatidine was found to be equivalent to that of ranitidine within a 20% region. Roxatidine users took significantly less antacids than ranitidine users (P < 0.05). There were no significant adverse effects due to roxatidine or ranitidine. Roxatidine is a safe effective drug in the treatment of duodenal ulcers with a healing rate comparable to that of ranitidine.  相似文献   
42.
Newlin  N; Silver  TM; Stuck  KJ; Sandler  MA 《Radiology》1981,139(1):155-159
Ultrasonic features of 21 surgically confirmed pyogenic liver abscesses in 18 patients were analyzed. Typical lesions were round or ovoid with a discrete, irregular, echo-poor margin. The number and intensity of internal echoes and sound transmission were variable. Such lesions can be aspirated percutaneously for definitive preoperative diagnosis. Pyogenic liver abscesses appear to have more ragged walls and are less frequently elliptical or multilocular than abscesses elsewhere in the abdomen.  相似文献   
43.
The great variability of cerebral cortical folding patterns raises major problems for the systematic study of functional-structural relationships. This paper describes a novel perspective for explaining this variability, a perspective that relies on gyri buried in the depth of the sulci. From this perspective we propose a generic model of folding, based on indivisible units, called sulcal roots, which correspond to the first folding locations during antenatal life. These units are organized according to a basic scheme allowing us to describe the cortical surface using a system of meridians and parallels. This scheme is thought to be stable across individuals at the fetal stage, and may be related to the protomap model. Variability at the adult stage is thought to result from the chaotic behavior of the folding process: inter-individual differences in cortical areas can lead to qualitatively different folding patterns. We have tested the capacity of this model to match actual cortical anatomy with a database of magnetic resonance images of 20 normal subjects, using new three-dimensional visualization tools giving access to shapes buried in the cortex.  相似文献   
44.
Ultrasound diagnosis of hydrocolpos and hydrometrocolpos   总被引:1,自引:0,他引:1  
Wilson  DA; Stacy  TM; Smith  EI 《Radiology》1978,128(2):451
  相似文献   
45.
46.
Chromatographic separation of highly polar basic drugs with ideal ionspray mass spectrometry volatile mobile phases is a difficult challenge. A new quantification procedure was developed using hydrophilic interaction chromatography-mass spectrometry with turbo-ionspray ionization in the positive mode. After addition of deuterated internal standards and simple clean-up liquid extraction, the dried extracts were reconstituted in 500 microL pure acetonitrile and 5 microL was directly injected onto a Waters Atlantis HILIC 150- x 2.1-mm, 3-microm column. Chromatographic separations of cocaine, seven metabolites, and anhydroecgonine were obtained by linear gradient-elution with decreasing high concentrations of acetonitrile (80-56% in 18 min). This high proportion of organic solvent makes it easier to be coupled with MS. The eluent was buffered with 2 mM ammonium acetate at pH 4.5. Except for m-hydroxy-benzoylecgonine, the within-day and between-day precisions at 20, 100, and 500 ng/mL were below 7 and 19.1%, respectively. Accuracy was also below +/- 13.5% at all tested concentrations. The limit of quantification was 5 ng/mL (%Diff < 16.1, %RSD < 4.3) and the limit of detection below 0.5 ng/mL. This method was successfully applied to a fatal overdose. In Switzerland, cocaine abuse has dramatically increased in the last few years. A 45-year-old man, a known HIV-positive drug user, was found dead at home. According to relatives, cocaine was self-injected about 10 times during the evening before death. A low amount of cocaine (0.45 mg) was detected in the bloody fluid taken from a syringe discovered near the corpse. Besides injection marks, no significant lesions were detected during the forensic autopsy. Toxicological investigations showed high cocaine concentrations in all body fluids and tissues. The peripheral blood concentrations of cocaine, benzoylecgonine, and methylecgonine were 5.0, 10.4, and 4.1 mg/L, respectively. The brain concentrations of cocaine, benzoylecgonine, and methylecgonine were 21.2, 3.8, and 3.3 mg/kg, respectively. The highest concentrations of norcocaine (about 1 mg/L) were measured in bile and urine. Very high levels of cocaine were determined in hair (160 ng/mg), indicating chronic cocaine use. A low concentration of anhydroecgonine methylester was also found in urine (0.65 mg/L) suggesting recent cocaine inhalation. Therapeutic blood concentrations of fluoxetine (0.15 mg/L) and buprenorphine (0.1 microg/L) were also discovered. A relatively high concentration of Delta(9)-THC was measured both in peripheral blood (8.2 microg/L) and brain cortex (13.5 microg/kg), suggesting that the victim was under the influence of cannabis at the time of death. In addition, fluoxetine might have enhanced the toxic effects of cocaine because of its weak pro-arrhythmogenic properties. Likewise, combination of cannabinoids and cocaine might have increase detrimental cardiovascular effects. Altogether, these results indicate a lethal cocaine overdose with a minor contribution of fluoxetine and cannabinoids.  相似文献   
47.
48.
49.
OBJECTIVE: To assess urinary morbidity within the first 6 months after transperineal prostate brachytherapy (TPBT) with 125I for localized prostate adenocarcinoma. PATIENTS AND METHODS: Between September 2000 and July 2001, 50 consecutive patients with favourable early-stage prostate cancer were treated with TPBT. Clinical and objective investigations, including uroflowmetry and postvoid residual urine measurements, were evaluated for short-term urinary morbidity; predictive factors were also sought. RESULTS: Thirty-eight (76%) patients developed urinary disorders, but severe urinary complications were exceptional. The International Prostate Symptom Score (IPSS) changed significantly during the first and third month after implantation and then improved during the sixth month. Concomitantly, the maximum and the average urinary flow rate deteriorated significantly. The variations in postvoid residual were less significant. An initial IPSS of > 8 and previous alpha-blocker treatment were identified as significant predictive factors of urinary morbidity, as were the TPBT dose received by 90% of the target volume and by 30% of the urethra, and the volume of prostate receiving 144 Gy. CONCLUSION: Urinary morbidity after TPBT is frequent but rarely exceptionally severe; patients must therefore be given full information. Patients with a higher initial IPSS or having had previous alpha-blocker treatment, with their associated dosimetric factors, are at greater risk of these urinary morbidity.  相似文献   
50.
Five patients at risk for primary central nervous system lymphoma (PCNSL) recurrence were treated with high-dose methylprednisolone (HDMP) to prevent 'trafficking' of malignant lymphocytes into the central nervous system (CNS). HDMP was chosen because of its ability to stabilize the 'blood brain barrier (BBB)'. Three men with newly diagnosed PCNSL, ages 62, 76 and 78y, whose survival was projected to be 6.6 months, began treatment after achieving complete response (CR) to initial radiation therapy alone and survived 27, 37 and 59 months after treatment. In none was death from recurrent disease in CNS but one patient did die of systemic non-Hodgkin's lymphoma (NHL) five years after PCNSL diagnosis. A 20 y old man was treated with HDMP after successful combined modality therapy and is alive 75+ months after initial diagnosis without evidence of disease recurrence. A 34 y old man relapsed after combined modality initial treatment and failed to respond to HDMP when treatment was begun after unsuccessful salvage therapy; he died of disease 12 months after initial diagnosis. There were no treatment complications. The promising results in this pilot study from the basis for a North Central Cancer Treatment Group (NCCTG) 96-73-51, a Phase 2 clinical trial of brain radiotherapy and HDMP for PCNSL patients 70y of age and older, a group of patients at high risk for toxicity from intensive combined modality therapy.  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