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   1177篇
  免费   42篇
  国内免费   2篇
耳鼻咽喉   13篇
儿科学   32篇
妇产科学   25篇
基础医学   89篇
口腔科学   95篇
临床医学   67篇
内科学   209篇
皮肤病学   16篇
神经病学   54篇
特种医学   127篇
外科学   266篇
综合类   8篇
预防医学   18篇
眼科学   52篇
药学   83篇
中国医学   14篇
肿瘤学   53篇
  2024年   2篇
  2023年   6篇
  2022年   7篇
  2021年   11篇
  2020年   19篇
  2019年   21篇
  2018年   11篇
  2017年   12篇
  2016年   28篇
  2015年   17篇
  2014年   29篇
  2013年   38篇
  2012年   58篇
  2011年   65篇
  2010年   25篇
  2009年   29篇
  2008年   71篇
  2007年   68篇
  2006年   84篇
  2005年   94篇
  2004年   70篇
  2003年   78篇
  2002年   64篇
  2001年   35篇
  2000年   43篇
  1999年   32篇
  1998年   9篇
  1997年   16篇
  1996年   8篇
  1995年   16篇
  1994年   9篇
  1993年   16篇
  1992年   20篇
  1991年   16篇
  1990年   8篇
  1989年   12篇
  1988年   13篇
  1987年   8篇
  1986年   5篇
  1985年   5篇
  1984年   6篇
  1983年   2篇
  1982年   5篇
  1981年   7篇
  1980年   6篇
  1979年   8篇
  1978年   3篇
  1977年   2篇
  1976年   3篇
  1974年   1篇
排序方式: 共有1221条查询结果,搜索用时 15 毫秒
1.
OBJECTIVE: The aim of the current study was to test the impact of dentin powder on the antimicrobial efficacy of bioactive glass S53P4 (BAG). STUDY DESIGN: BAG was suspended (preincubated) in saline at 37 degrees C for different time periods with or without human dentin powder, hydroxylapatite, or decalcified dentin. Subsequently, Enterococcus faecalis ATCC 29212 cells were added to these suspensions and bacterial recovery measured with and without the use of gentle sonication. Furthermore, survival of bacteria in test and control suspensions was assessed over time. Supernatants of suspensions were analyzed for their element contents using atomic absorption spectrophotometry. The effects of pH, silica, and osmolarity on E faecalis viability were assessed using specifically prepared solutions. RESULTS: BAG preincubated with dentin powder caused a significant (P < .05) decrease in viability compared to pure BAG suspensions. This was not based on adherence of bacteria to solid particles or agglutination of the cells, because sonication did not increase bacterial yields. Hydroxylapatite and decalcified dentin did not increase BAG killing efficacy. The additive effect of BAG + dentin powder was dose dependent, occurred only with solids in suspension, and increased with suspension time. An augmented dissolution of glass components, especially silicon, was measured in BAG + dentin powder compared to pure BAG suspensions or counterparts containing hydroxylapatite or decalcified dentin. High osmolarity per se did not affect E faecalis viability, whereas high pH and silica levels did. CONCLUSION: The observed phenomenon was related to an increased BAG dissolution triggered by dentin powder, causing elevated local pH and silica levels.  相似文献   
2.
A study of the angiographic findings in consecutive civilian patients with cranial gunshot wounds examined in the acute stage has not been done. Most prior clinical studies have evaluated the findings in survivors in the subacute or chronic stages and have often been of war-time casualties. We determined the clinicoradiologic features of six cases of posttraumatic intracranial aneurysm, vascular occlusion, or arteriovenous fistula caused by penetrating missiles among 12 civilian patients who were examined in the acute posttraumatic stage (within 48 hr of injury) during a 1-year period. Three internal carotid/vertebral artery aneurysms, one external carotid artery aneurysm, one combined aneurysm/arteriovenous fistula of the vertebrobasilar circulation, and one cerebral venous occlusion were identified. The 50% overall prevalence of major vascular lesions in this series of civilian patients with penetrating missile injuries examined in the acute stage suggests these injuries are more common than previously suspected. It may indicate that selective cerebral angiography should be considered in the evaluation of the cranial vascular system of such persons.  相似文献   
3.
Acute subdural hematoma: Outcome and outcome prediction   总被引:3,自引:0,他引:3  
Patients with traumatic acute subdural hematoma were studied to determine the factors influencing outcome.Between January 1986 and August 1995, we collected 113 patients who underwent craniotomy for traumatic acute subdural hematoma. The relationship between initial clinical signs and the outcome 3 months after admission was studied retrospectively.Functional recovery was achieved in 38% of patients and the mortality was 60%. 91% of patients with a high Glasgow Coma Scale (GCS) score (9–15) and 23% of patients with a low GCS score (3–8) achieved functional recovery. All of 14 patients with a GCS score of 3 died. The mortality of patients with GCS scores of 4 and 5 was 95% to 75%, respectively. Patients over 61 years old had a mortality of 73% compared to 64% mortality for those aged 21–40 years. 97% of patients with bilateral unreactive pupil and 81% of patients with unilateral unreactive pupil died. The mortality rates of associated intracranial lesions were 91% in intracerebral hematoma, 87% in subarachnoid hemorrhage, 75% in contusion.Time from injury to surgical evacuation and type of surgical intervention did not affect mortality. Age and associated intracranial lesions were related to outcome. Severity of injury and pupillary response were the most important factors for predicting outcome.  相似文献   
4.
We report an unusual case of an enterovesical fistula secondary to adenocarcinoma of the appendix.  相似文献   
5.
Renal pelvic carcinoma is a rare tumor. There are several staging systems currently in use based on a bladder cancer staging model. An analysis of the American Cancer Society, Illinois Division, experience with 611 cases of renal pelvic transitional cell carcinoma suggested that the kidney parenchyma may be a determinant in the anatomic spread of disease. A tumor-node-metastasis system for renal pelvic (separate from ureteral) cancer is recommended.  相似文献   
6.
Whistling face syndrome or cranio-carpotarsal dysplasia is a very rare disorder that consists of a characteristics facies and digital abnormalities. Magnetic resonance imaging investigation of the brain in this syndrome has not been reported previously. This communication describes the brain malformations in an infant with the syndrome, which covered delayed myelination, thickened and infolded cortices (cortical dysplasia), dysplastic corpus callosum, and agenesis of the inferior vermis.  相似文献   
7.
8.
A new triterpenoidal saponin having hederagenin as the aglycone was isolated from the roots of SYMPHYTUM OFFICINALE L. The structure of this saponin was elucidated by FAB-MS, (1)H-, (13)C-NMR, 2D-NMR analyses and chemical studies as 3- O-[beta- D-glucopyranosyl-(1-->4)-alpha- L-arabinopyranosyl]-hederagenin 28- O-[beta- D-glucopyranosyl-(1-->6)-beta- D-glucopyranosyl] ester.  相似文献   
9.
Three adult patients are reported with asymptomatic localized widening of the central canal of the spinal cord. These patients were followed for a period of 24 years by imaging and/or clinical history and physical examination without evidence of signs or symptoms related to the spinal cord. This condition probably represents persistence into adult life of a fetal configuration of the central canal of the spinal cord. This process may be termed "idiopathic localized hydromyelia" to distinguish it from syringomyelia secondary to such causes as Chiari malformation, trauma, infection, or neoplasm.  相似文献   
10.
Purpose: To evaluate the effects of topical timolol and apraclonidine on retrobulbar blood flow velocity waveforms in a group of healthy volunteers.Methods: Apraclonidine 1% and timolol maleate 0.5% single dose administrations were crossed over double masked in 12 healthy volunteers. The intraocular pressure measurements were followed by Doppler examination of the ophthalmic artery and the central retinal artery.Results: Intraocular pressure was reduced significantly on both treated and fellow eyes after timolol (p = 0.003, p = 0.04 respectively) and after apraclonidine (p = 0.002, p = 0.01 respectively). After apraclonidine administration end diastolic velocity, mean velocity decreased and pulsatility index increased in the ophthalmic artery of both treated and fellow eyes. Resistivity index increased and peak systolic velocity decreased only in the ophthalmic artery of treated eyes. All Doppler indices remained nonsignificant for central retinal artery of both eyes.After timolol administration there were no significant changes of the Doppler indices in the ophthalmic artery and central retinal artery of the treated and fellow eyes.Conclusion: Topical timolol and apraclonidine significantly reduced the intraocular pressure. Single dose administration of apraclonidine 1% increased the vascular impedance distal to the ophthalmic artery. On the other hand, timolol 0.5% had no effect on vascular impedance.  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