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   2371篇
  免费   116篇
  国内免费   14篇
耳鼻咽喉   6篇
儿科学   59篇
妇产科学   15篇
基础医学   263篇
口腔科学   66篇
临床医学   207篇
内科学   532篇
皮肤病学   84篇
神经病学   95篇
特种医学   58篇
外科学   423篇
综合类   16篇
预防医学   184篇
眼科学   15篇
药学   226篇
中国医学   2篇
肿瘤学   250篇
  2023年   15篇
  2022年   37篇
  2021年   42篇
  2020年   26篇
  2019年   46篇
  2018年   61篇
  2017年   46篇
  2016年   43篇
  2015年   54篇
  2014年   68篇
  2013年   70篇
  2012年   128篇
  2011年   118篇
  2010年   57篇
  2009年   58篇
  2008年   69篇
  2007年   95篇
  2006年   85篇
  2005年   79篇
  2004年   79篇
  2003年   88篇
  2002年   109篇
  2001年   89篇
  2000年   67篇
  1999年   67篇
  1998年   24篇
  1997年   15篇
  1996年   14篇
  1995年   15篇
  1994年   16篇
  1992年   57篇
  1991年   32篇
  1990年   56篇
  1989年   50篇
  1988年   47篇
  1987年   58篇
  1986年   68篇
  1985年   52篇
  1984年   30篇
  1983年   33篇
  1982年   15篇
  1979年   22篇
  1977年   13篇
  1976年   14篇
  1974年   15篇
  1971年   20篇
  1969年   14篇
  1968年   11篇
  1967年   13篇
  1966年   12篇
排序方式: 共有2501条查询结果,搜索用时 15 毫秒
1.
The aim of this study was to investigate retrospectively the efficacy of expandable metallic stents (EMSs) for severe respiratory distress in patients with central airway obstruction. Twenty patients with central airway obstructions were treated with an EMS. An intraluminal stricture was present in 15 and an extraluminal stricture in 5 patients. Of the 15 patients with intraluminal stenosis, 11 exhibited symptomatic improvement. All 11 patients had tumor infiltration occupying less than 50% of the endoluminal diameter. The other four patients with intraluminal stenosis had tumor infiltration occupying > 50% of the endoluminal diameter and demonstrated no improvement. All five patients with extraluminal stenosis were improved. EMS is useful for an extraluminal stricture in the central airway and the effect of EMS for intraluminal stenosis is related to the degree of infiltration and of tumor progression itself.   相似文献   
2.
3.
Purpose. The locomotive activity changes after intravenous (i.v.) administration of methylphenidate (MPD) in rats were pharmacodynamically analyzed. Methods. MPD concentration in plasma, MPD concentration and dopamine (DA) level in striatal dialysate collected by microdialysis method, and the locomotor activity after i.v. administration of MPD (2, 5 and 10 mg/kg doses) were used for the analysis. Results. The transport of MPD from plasma to the interstitial fluid in the brain could be expressed by the linear two-compartment model. The clockwise hysteresis between the MPD concentration and the DA level in the dialysate could be explained by the pharmacodynamic model considering Michaelis-Menten type reuptake process of the extracellular DA into the terminal of the dopaminergic nerve and its competitive inhibition by the extracellular MPD. The inhibition constant (Ki) of MPD for DA reuptake was estimated to be 41.3 ± 73.8 nM (mean ± SE), which was closely consistent with the in vitro value after correction with dialysis recovery. The relationship between DA level in dialysate and locomotor activity was expressed by the Emax model considering two contrary effects, hyperkinesia and stereotypy. The bi-phasic locomotor activity-time profiles after high dose of MPD could be represented by this model. Conclusions. The developed model made it possible to explain the tolerance in DA increase and the complicated locomotive change induced by MPD, and may be useful for other DA reuptake inhibitors, such as amphetamine and methamphetamine.  相似文献   
4.
The only workers presently exposed to bagasse dust in Japan are the employees of sugar refineries and lacquerware factories. A follow up study of six former cases of bagassosis from among the retired employees of a paper board factory, closed since 1973, showed that none of the subjects still had bagassosis. Examinations of 70 employees of a sugar refinery for allergic reactions also showed no case of bagassosis. Seven cases with suspicious shadows of bagassosis on chest radiographs and four cases with positive serum precipitin to stored bagasse were, however, found among those 70 subjects. The results show the disappearance of a past episode of bagassosis and the possibility of a new occurrence of bagassosis among the employees of sugar refineries and lacquerware factories in the near future in Japan.  相似文献   
5.
A 65-year-old woman with diabetes mellitus and chronic otitis media developed headache, fever, and hoarseness, all of which did not responded to the oral antibiotics. As stiff neck and lower cranial nerve palsies appeared, bacterial meningitis was suspected. Neurological examination revealed the right hearing disturbance, right recurrent laryngeal nerve palsy, left sternocleidomastoid muscle atrophy and bilateral tongue atrophy. The CSF examination revealed mild pleocytosis and elevated protein, but no bacterial organism was cultured from the CSF. CT scans showed bilateral mastoiditis, and the right mastoid process and a posterior part of the petrous bone were eroded, indicating the exposed bony structures to the posterior fossa. MRI scans demonstrated the thickening of the dura mater of the posterior fossa and the right cerebellar tentorium. This is a rare example of bacterial pachymeningitis of the posterior fossa, the clinical symptoms and MRI findings of which resolved solely by antimicrobial agents without corticosteroid.  相似文献   
6.
7.
8.
It is believed that gingivitis at puberty is exaggerated by alterations of the hormonal balance. We have suggested that estradiol promotes the gingivitis at puberty while progesterone reduces it (J. Hiroshima Univ. Dent. Soc. 19: 1987). But the mechanisms of these hormones which influence gingival inflammation are not known yet. Therefore, we hypothesized that one of the possible mechanisms of sex hormones on gingival inflammation is through their action on polymorphonuclear leucocytes (PMNs) function because PMNs play an important role in periodontal disease. The purpose of this study was to investigate the effect of sex hormones on PMNs function, especially their migration in vitro. PMNs and plasma were obtained from heparinized peripheral blood of 23 healthy adults. PMNs were preincubated at 37 degrees C for 15 minutes with progesterone or 17 beta-estradiol at designated concentrations. After preincubation, PMNs migration was measured using 48-well chemotaxis micro-chamber with N-formyl-methionyl-leucyl-phenylalanine (FMLP) as chemoattractant. The levels of estradiol and progesterone in the plasma were determined using Direct Radioimmunoassay Kits and the correlation between sex hormone levels and PMNs migration was investigated. PMNs migration to 10(-6) M FMLP was enhanced significantly by progesterone at the concentrations of 200 ng/ml while it was reduced by estradiol at 0.4 ng/ml and 2.0 ng/ml. Random migration of PMNs was enhanced significantly by progesterone at 20 ng/ml while it was reduced by estradiol at 0.4 ng/ml. Significant positive correlation was found between progesterone level in plasma and the PMNs migration in vitro. Estradiol level in plasma did not have any correlation with the PMNs migration in vitro.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
9.
10.
The results of repairing cleft lip by aesthetic plastic surgery are now excellent. However, the cleft lipnose deformity is still very difficult to repair with the present techniques. A technique that can repair the cleft lip-nose deformity with good results is presented. The technique is divided into three parts: Part I consists of nasal repair of the primary cleft lip. Part II is nasal reconstruction as a secondary operation with or without lip repair. For example, nasal reconstruction may be secondary to repair of deformities of the sill, rim, limen nasi, septum, or nasal bones. Part III is an aesthetic nasal operation such as rhinoplasty, mentoplasty, or zygomaplasty.  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