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   3291篇
  免费   206篇
  国内免费   24篇
耳鼻咽喉   30篇
儿科学   47篇
妇产科学   77篇
基础医学   581篇
口腔科学   37篇
临床医学   288篇
内科学   854篇
皮肤病学   47篇
神经病学   253篇
特种医学   133篇
外科学   314篇
综合类   10篇
预防医学   90篇
眼科学   39篇
药学   415篇
中国医学   19篇
肿瘤学   287篇
  2023年   12篇
  2022年   13篇
  2021年   46篇
  2020年   30篇
  2019年   33篇
  2018年   41篇
  2017年   36篇
  2016年   60篇
  2015年   65篇
  2014年   96篇
  2013年   114篇
  2012年   226篇
  2011年   230篇
  2010年   129篇
  2009年   117篇
  2008年   232篇
  2007年   228篇
  2006年   272篇
  2005年   251篇
  2004年   217篇
  2003年   210篇
  2002年   233篇
  2001年   35篇
  2000年   31篇
  1999年   42篇
  1998年   59篇
  1997年   36篇
  1996年   25篇
  1995年   32篇
  1994年   22篇
  1993年   33篇
  1992年   17篇
  1991年   13篇
  1990年   22篇
  1989年   22篇
  1988年   16篇
  1987年   17篇
  1986年   15篇
  1985年   13篇
  1983年   21篇
  1982年   23篇
  1981年   8篇
  1980年   12篇
  1979年   10篇
  1978年   9篇
  1977年   8篇
  1976年   10篇
  1975年   15篇
  1973年   8篇
  1970年   8篇
排序方式: 共有3521条查询结果,搜索用时 640 毫秒
1.
2.
Age determines memory for face identity and expression   总被引:1,自引:1,他引:0  
Background: The recognition of facial expressions is an important component of emotion processing which contributes to interactional behavior. One of the factors highly associated with potential decline of ability in behavioral tasks is age. Methods: We have investigated age‐related changes in facial identity and expression memory of healthy subjects in three age groups: young adults (20–40 years), elderly adults (60–80 years) and, for the first time in the literature, very old adults (over 80 years of age). Using a picture test, photographs of faces with happy or angry expressions were presented to study participants during the encoding task, and the memory for identity and emotional facial expression was investigated in a subsequent recognition task showing emotionally neutral faces. Half of the faces presented in the recognition task were initially shown in the encoding task. Results: Age interacted with the memory process: the ability to recognize both facial identity and emotional expression declined with advanced age. Happy facial expressions were better recognized in all age groups. Although there was a continuous overall decrease in recognition of both happy and angry expressions with advanced age, the effect favoring happy facial expressions was stable also in very old adults. Other factors such as gender or educational level did not affect the memory process for facial expressions. Conclusions: Our findings suggest that age is a significant determinant of memory for facial identity and emotional expression, and that, similar to younger adults, the recognition process of the elderly favors happy emotional facial expressions.  相似文献   
3.
We report a case of synchronous olfactory bulb meningioma and undifferentiated carcinoma of the nose and paranasal sinuses that involved and destroyed the anterior skull base and mimicked intracranial invasion by a carcinoma. The heterogeneity of tissue types in the skull base gives rise to a diverse variety of benign and malignant neoplasms which have totally different prognoses. Synchronous development of benign and malignant primary tumors both originating from and involving the skull base at the same location is very rare and may cause confusion for both the skull base surgeon and neuroradiologist.  相似文献   
4.
股骨干骨折--逆行穿钉与顺行穿钉的探讨   总被引:1,自引:0,他引:1  
在对股骨骨折进行逆行和顺行置入髓内钉治疗时,两种治疗方法产生很高的愈合率和相近的畸形愈合率。虽然未经过一致的认定,但那些接受顺行穿钉治疗的患者愈合较快。患者在接受逆行穿钉治疗后膝关节疼痛频繁出现,然而髋关节疼痛和异位骨化现象却在接受顺行穿钉治疗的患者中存在。患其它并发症的几率也无显著增长。因此不能决定功能结果。  相似文献   
5.
6.
7.
The influence of angiotensin II (ANGII) on the dynamic characteristics of renal blood flow (RBF) was studied in conscious dogs by testing the response to a step increase in renal artery pressure (RAP) after a 60 s period of pressure reduction (to 50 mmHg) and by calculating the transfer function between physiological fluctuations in RAP and RBF. During the RAP reduction, renal vascular resistance (RVR) decreased and upon rapid restoration of RAP, RVR returned to baseline with a characteristic time course: within the first 10 s, RVR rose rapidly by 40 % of the initial change (first response, myogenic response). A second rise began after 20–30 s and reached baseline after an overshoot at 40 s (second response, tubuloglomerular feedback (TGF)). Between both responses, RVR rose very slowly (plateau). The transfer function had a low gain below 0.01 Hz (high autoregulatory efficiency) and two corner frequencies at 0.026 Hz (TGF) and at 0.12 Hz (myogenic response). Inhibition of angiotensin converting enzyme (ACE) lowered baseline RVR, but not the minimum RVR at the end of the RAP reduction (autoregulation-independent RVR). Both the first and second response were reduced, but the normalised level of the plateau (balance between myogenic response, TGF and possible slower mechanisms) and the transfer gain below 0.01 Hz were not affected. Infusion of ANGII after ramipril raised baseline RVR above the control condition. The first and second response and the transfer gain at both corner frequencies were slightly augmented, but the normalised level of the plateau was not affected. It is concluded that alterations of plasma ANGII within a physiological range do not modulate the relative contribution of the myogenic response to the overall short-term autoregulation of RBF. Consequently, it appears that ANGII augments not only TGF, but also the myogenic response.  相似文献   
8.
BACKGROUND: High-dose chemotherapy followed by autologous blood stem cell transplantation induces remission of plasma cell dyscrasia in patients with AL amyloidosis. The impact of this treatment on the glomerular amyloid mass is still unknown. METHODS: In the present study, the quantity of the renal amyloid mass before and more than 3 years after high-dose melphalan treatment and autologous blood stem cell transplantation was assessed in two patients. At the time of the second renal biopsy, both patients were in complete remission without detectable serum and urinary monoclonal IgA-lambda and a normal percentage of plasma cells in the bone marrow. RESULTS: In both patients with biopsy-proven AL amyloidosis, urinary protein excretion decreased from 7 g/24 h to <2 g/24 h more than 3 years after autologous blood stem cell transplantation. In contrast, glomerular amyloid deposits persisted, as shown in the second biopsy. CONCLUSION: Despite complete remission of the plasma cell dyscrasia and improvement of glomerular permeability, the amount of glomerular amyloid mass did not regress.  相似文献   
9.

Background  

While gastrointestinal problems are common in ICU patients with multiple organ failure, gastrointestinal failure has not been given the consideration other organ systems receive. The aim of this study was to evaluate the incidence of gastrointestinal failure (GIF), to identify its risk factors, and to determine its association with ICU mortality.  相似文献   
10.
Abstract Whiplash injury of the cervical spine is a frequent issue in medical expertises and causes enormous consequential costs for motor insurance companies. Some authors accuse posttraumatic changes of alar ligaments to be causative of consequential disturbances, although biomechanical experiments achieve contradictory results and neuropsychiatric studies do not support this thesis. MRI provides excellent visualization of alar ligaments. However, signal alterations of alar ligaments must be differentiated from common normal variants. Functional MRI provides no diagnostic yield.   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