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   35203篇
  免费   2271篇
  国内免费   271篇
耳鼻咽喉   453篇
儿科学   687篇
妇产科学   546篇
基础医学   4397篇
口腔科学   1652篇
临床医学   2959篇
内科学   9431篇
皮肤病学   417篇
神经病学   3474篇
特种医学   1411篇
外科学   5610篇
综合类   106篇
一般理论   6篇
预防医学   1538篇
眼科学   558篇
药学   1825篇
中国医学   73篇
肿瘤学   2602篇
  2023年   338篇
  2022年   559篇
  2021年   1278篇
  2020年   773篇
  2019年   1060篇
  2018年   1236篇
  2017年   986篇
  2016年   1092篇
  2015年   1165篇
  2014年   1506篇
  2013年   1850篇
  2012年   2860篇
  2011年   2778篇
  2010年   1563篇
  2009年   1422篇
  2008年   2249篇
  2007年   2372篇
  2006年   2107篇
  2005年   1925篇
  2004年   1728篇
  2003年   1575篇
  2002年   1394篇
  2001年   348篇
  2000年   321篇
  1999年   301篇
  1998年   265篇
  1997年   221篇
  1996年   169篇
  1995年   158篇
  1994年   140篇
  1993年   116篇
  1992年   165篇
  1991年   130篇
  1990年   127篇
  1989年   90篇
  1988年   128篇
  1987年   105篇
  1986年   75篇
  1985年   108篇
  1984年   77篇
  1983年   64篇
  1982年   60篇
  1981年   45篇
  1979年   71篇
  1978年   53篇
  1977年   41篇
  1975年   47篇
  1974年   51篇
  1973年   66篇
  1972年   54篇
排序方式: 共有10000条查询结果,搜索用时 93 毫秒
101.
Tibial plateau fractures are complex injuries which, if not adequately treated, can lead to invalidating sequelae. They constitute on average about 1% of all fractures, and up to 8% in patients over 65 years, and can be caused by both high- and low-energy trauma. Unlike in younger subjects, treatment of tibial plateau fractures in the elderly is not univocal and depends on the patient’s functional needs, bone quality and systemic comorbidities. In this retrospective study, 49 patients with a mean age of 72 years, who underwent surgical treatment of a tibial plateau fracture, were assessed by the Rasmussen’s clinical and radiological grading systems. Clinical and radiographic outcomes were satisfactory in 75.5 and 59.1% of cases, respectively. Data were also analyzed, in terms of fracture type, age and gender, to detect any statistically significant correlation between these parameters and clinical and radiographic outcomes.  相似文献   
102.
Introduction Postoperative treatment for colorectal cancer depends on tumor stage as defined by the International Union Against Cancer (UICC). Adjuvant chemotherapy is not recommended in patients without lymph node involvement (UICC stages I and II). As many as 20–30% of these patients, however, will develop recurrence. Aims and objectives We conducted this study to determine the presence of disseminated tumor cells in the lymph nodes by quantitative real-time polymerase chain reaction (QRT-PCR) for cytokeratin 20 (CK20) in an attempt to provide supplementary information compared to histopathological findings. Materials and methods Using a standard QRT-PCR assay, we examined primary tumors and 391 lymph nodes from 31 patients with completely resected colorectal cancer. Results Of the 31 primary tumors, 29 were positive for CK20 by QRT-PCR. Discussion An examination of the lymph nodes from the 29 patients with CK20-positive primary tumors revealed that 35 (92.1% sensitivity) of the 38 histopathologically positive lymph nodes and 54 (16.7%) of the 324 histopathologically negative lymph nodes were positive by molecular analysis. CK20 expression was detected in 10 (100%) of 10 patients with a histopathologically positive lymph node status (pN1). In 9 (47.4%) of 19 patients with negative histopathological results (pN0), we detected a CK20 mRNA signal in at least one lymph node. Whereas eight patients with histopathologically negative lymph nodes could be upstaged on the basis of the molecular findings, no patient would be downstaged. Conclusion Our results suggest that QRT-PCR for CK20 is a useful tool for the quantitative detection of micrometastases in the regional lymph nodes. We introduce a standardized procedure that integrates a molecular diagnostic technique in the clinical staging.  相似文献   
103.
104.
105.
OBJECTIVE: The study was designed to test application of ultraviolet light to root canal walls, as a mean of complementary immediate disinfection after the use of sodium hypochlorite. STUDY DESIGN: Root canals were infected ex vivo with Enterococcus faecalis for 48 hours. Non-attached bacteria were washed away, and the remaining attached bacteria were subjected to disinfection, with 5% sodium hypochlorite alone or followed by exposure to ultraviolet light (254 nm, 300 mJ/cm(2)). Root canals were then tested for remaining viable bacteria. Canals were obturated and tested again after 14 days. RESULTS: Sodium hypochlorite alone achieved negative cultures in only 47% of the cases, but 96% was achieved with sodium hypochlorite followed by ultraviolet light (P < .001). This status was also maintained after 14 days. CONCLUSIONS: Illumination of root canals with ultraviolet light may be an effective supplementary means to achieve immediate disinfection of infected root canals.  相似文献   
106.
107.
The lymph flow of the thoracic duct, the protein content of the lymph, bile flow and bile composition are studied during the first three hours of the recirculation phase in experimental liver transplantation. It is established that the lymph flow and the protein content of the thoracic duct decrease as a result of the interruption of hepatic lymph flow of a high protein concentration. The change in bile composition and flow is due to the reduced bile acid excretion of the transplanted hepatic tissue.  相似文献   
108.
109.
To analyse the effect of concomitant cognitive or motor task performance on balance control in Parkinson's disease (PD), we performed a posturographic study in 24 PD patients and in 20 sex- and age-matched control subjects. Postural sway was measured with eyes open (EO) and eyes closed (EC) during quiet stance and during performance of calculation or motor sequence of thumb opposition to the other fingers. No difference of centre of foot pressure (COP) parameters was observed during quiet standing (either EO or EC) between patients and controls, but visual deprivation induced in both groups a worsening of postural stability. COP area was significantly increased in PD patients during dual task performance, whereas no difference of COP path and x-y axes was observed. The effects induced by the performance of cognitive or motor task were significantly more evident in PD patients with clinical evidence of postural instability (presence of prior falls in the history). This study demonstrates that dual task interference on postural control can be observed in PD patients during performance of cognitive as well as motor tasks. The balance deterioration during dual task performance was significantly enhanced in patients with history of prior falls. These findings have some implications for the strategies to be used in reducing the risk of fall in PD.  相似文献   
110.
Serum immunoglobulins and the activity of natural killer (NK) cells of 50 epileptic patients (eight with idiopathic generalized epilepsy and 42 with cryptogenic partial epilepsy) and 28 controls have been studied. The values of IgA, IgG and IgM were the same-in patients and controls. The NK activity in controls was linearly related to the effector-to-target ratio, but this linear relationship was not observed in epileptic patients. The cytotoxic activity of NK cells at the lowest effector-to-target ratio was significantly greater in patients than in controls. This increase was observed in each therapy group. Our results seem to confirm a disturbance of the immune system in epileptic patients and suggest that this modification of cellular immunity is not a drug effect but is related to the illness itself.  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