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   3389篇
  免费   184篇
  国内免费   18篇
耳鼻咽喉   31篇
儿科学   95篇
妇产科学   122篇
基础医学   454篇
口腔科学   100篇
临床医学   303篇
内科学   613篇
皮肤病学   76篇
神经病学   287篇
特种医学   62篇
外科学   366篇
综合类   21篇
一般理论   3篇
预防医学   530篇
眼科学   96篇
药学   211篇
中国医学   22篇
肿瘤学   199篇
  2024年   3篇
  2023年   49篇
  2022年   109篇
  2021年   184篇
  2020年   97篇
  2019年   151篇
  2018年   168篇
  2017年   117篇
  2016年   109篇
  2015年   111篇
  2014年   175篇
  2013年   211篇
  2012年   287篇
  2011年   305篇
  2010年   176篇
  2009年   149篇
  2008年   220篇
  2007年   191篇
  2006年   164篇
  2005年   160篇
  2004年   135篇
  2003年   89篇
  2002年   84篇
  2001年   12篇
  2000年   7篇
  1999年   7篇
  1998年   14篇
  1997年   18篇
  1996年   9篇
  1995年   7篇
  1994年   8篇
  1993年   5篇
  1992年   4篇
  1989年   5篇
  1988年   2篇
  1987年   5篇
  1984年   6篇
  1983年   3篇
  1982年   3篇
  1981年   3篇
  1979年   3篇
  1976年   3篇
  1974年   3篇
  1965年   2篇
  1959年   1篇
  1954年   1篇
  1944年   1篇
  1943年   1篇
  1942年   1篇
  1934年   2篇
排序方式: 共有3591条查询结果,搜索用时 0 毫秒
41.
42.
43.
BackgroundThe sphenoid sinus is considered as the most variable pneumatized structure of the skull.PurposeThe aim of the present study was to determine the prevalence of the Onodi cell as well as to evaluate the relationship between the sphenoid sinus type of pneumatization and the presence of surrounding neurovascular protrusion using cone beam computed tomography (CBCT).MethodsThe CBCT images of 500 patients/996 sides [203 males (40.6%) and 297 females (59.4%)] were analyzed in this study. The type of sphenoid sinus pneumatization, prevalence of internal carotid artery (ICA) and optic nerve (ON) protrusion and dehiscence, and also the frequency of Onodi cell were assessed.ResultsThe percentages of the conchal, presellar, sellar, postsellar (a), and postsellar (b) types of pneumatization were 1%, 11.5%, 35.5%, 38.9%, and 13.1%, respectively. The more the sphenoid sinuses pneumatized, the greater the frequency of ON and ICA protrusion and dehiscence of their wall to the sinus. The prevalence of Onodi cell was 38.8%. A significant correlation was found between ON dehiscence and the presence of Onodi cells.ConclusionThe present study demonstrated a significant relationship between the sinus type and frequency of neurovascular protrusions. Therefore, the sphenoid sinus extent of pneumatization might be useful in predicting the risk of iatrogenic damage to the surrounding structures.  相似文献   
44.

Purpose

To analyze the relationship between oxygen desaturation episodes during a laboratory-based ADL protocol and in real-life routine in patients with stable chronic obstructive pulmonary disease (COPD).

Methods

Twenty patients with stable COPD (12 men, 70 ± 7 years, FEV1% 54 ± 15 predicted) with no indication for long-term oxygen therapy (LTOT) were submitted to assessments including ADL performance by the Londrina ADL Protocol (LAP) and level of physical activity in daily life, both while submitted to simultaneous activity and pulse oximeter monitoring.

Results

Episodes of desaturation ≥ 4% (ED ≥ 4%) during the LAP were correlated both with ED ≥ 4% in daily life (r = 0.45) and number of episodes of SpO2 under 88% (ED < 88%) in daily life (r = 0.59). ED < 88% during the LAP was also correlated with ED < 88% in daily life (r = 0.51), explaining 43% of its variance.

Conclusion

In stable patients with COPD and no indication of LTOT, episodes of desaturation during a lab-based ADL protocol are moderately related to episodes of desaturation in daily (real) life, especially those episodes under 88%.
  相似文献   
45.
Consensus-derived structural determinants of the ankyrin repeat motif   总被引:13,自引:0,他引:13       下载免费PDF全文
The ankyrin repeat is one of the most common, modular, protein-protein interaction motifs in nature. To understand the structural determinants of this family of proteins and extract the consensus information that defines the architecture of this motif, we have designed a series of idealized ankyrin repeat proteins containing one, two, three, or four repeats by using statistical analysis of approximately 4,000 ankyrin repeat sequences from the PFAM database. Biophysical and x-ray crystallographic studies of the three and four repeat constructs (3ANK and 4ANK) to 1.26 and 1.5 A resolution, respectively, demonstrate that these proteins are well-folded, monomeric, display high thermostability, and adopt a very regular, tightly packed ankyrin repeat fold. Mapping the degree of amino acid conservation at each position on the 4ANK structure shows that most nonconserved residues are clustered on the surface of the molecule that has been designated as the binding site in naturally occurring ankyrin repeat proteins. Thus, the consensus amino acid sequence contains all information required to define the ankyrin repeat fold. Our results suggest that statistical analysis and the consensus sequence approach can be used as an effective method to design proteins with complex topologies. These generic ankyrin repeat proteins can serve as prototypes for dissecting the rules of molecular recognition mediated by ankyrin repeats and for engineering proteins with novel biological functions.  相似文献   
46.
47.
Trauma und Berufskrankheit - Frakturen der Mittelhandknochen verlaufen nicht selten komplikationsbehaftet und zeigen einen durch Delayed Union oder Pseudarthrosenbildung verzögerten...  相似文献   
48.

Background

Septic arthritis of the costovertebral thoracic joint is a rare site infection. We report an isolated case of septic arthritis of the 10th costo-vertebral right joint with osteitis due to Staphylococcus aureus.

Case presentation

A 59 year old Tunisian man presented with a 2 months history of dorsal spinal pain with fever, associated with asthenia, anorexia and loss of weight. There was a raised C-reactive protein (176 mg/L) and erythrocyte sedimentation rate (100 mm/1st h). Tests for tuberculosis and brucellosis were negative. In the present patient, the clinical symptoms were unspecific with lack of obvious predisposing factors. He had neither history of taking immunosuppressors nor of any disease indicative of immunodeficiency. Thoraco-abdominal computed tomography (CT) showed a lytic lesion centered on the 10th costo-vertebral right joint and histo-pathologic exam of the costo-vertebral puncture confirmed chronic active osteitis and bacteriologic culture allowed identifying methicillin-sensitive Staphylococcus aureus. The patient was treated with ciprofloxacin 1500 mg/day, associated with daily rifampin (20 mg/kg) for total treatment duration of 12 weeks after consulting infectious disease specialists. After a follow-up of 6 months, the patient remained asymptomatic and the markers of inflammation negative.

Conclusion

Septic arthritis of costovertebral joints should be considered when a patient presents with back pain, fever and elevated inflammatory markers. The diagnosis of septic arthritis of costovertebral joints remain a challenge to clinicians. CT is important to confirm a diagnosis and guide costovertebral biopsy and culture. Early and appropriate antibiotic therapy is important for a required outcome.  相似文献   
49.
We have previously shown that the serum aminoterminal propeptide of type III procollagen (PIIINP) is a prognostic factor for survival in localised soft-tissue sarcomas, and that elevated values are frequent in metastatic discase. In the present study PIIINP is analysed during chemotherapy in 26 patients with advanced sarcomas. Non-responders had a significantly higher pretreatment level of PIIINP than responders (P=0.05), when only patients with no recent therapeutic interventions were studied. However, during chemotherapy PIIINP followed the clinical course of the malignant disease in only a minority of patients. Patients with recent surgery or recently completed chemotherapy had an increased pretreatment PIIINP value (P=0.03). In these patients PIIINP declined during chemotherapy irrespective of tumour response. A pretreatment PIIINP level within the reference range tended to increase with time irrespective of response. Moreover, the values taken during a chemotherapy infusion were significantly higher than those immediately preceding the corresponding cycle (P=0.001). Our results suggest that pretreatment PIIINP is of value as a prognostic factor for chemotherapy response in patients with advanced sarcomas. During chemotherapy PIINP is of minor importance in monitoring response because of the influence of chemotherapy and other therapeutic interventions on the level of PIIINP.This study was supported in part by grants from the Finnish Cancer Foundations, the Medical Research Council of the Academy of Finland and Finska Läkaresällskapet (Finnish Medical Society)  相似文献   
50.
Young women in sub-Saharan Africa are disproportionately affected by HIV, making the development of women initiated and controlled methods of prevention, including microbicides, a priority. Adherence is pivotal to microbicide efficacy and partner related factors are known to impact adherence. An analysis of disclosure of gel use to sexual partners and adherence in CAPRISA 004 women was conducted to better understand this relationship. Partner disclosure was significantly associated with a modest 4.2 % increased adherence (71.0 vs. 66.8 %, p = 0.03). Most women rated the experience of disclosure as positive, despite 6.7 % of partners expressing a negative reaction.Participants who disclosed were more likely to reside with their regular partner (14.4 vs. 8.4 %; p = 0.01) and reported consistent condom use at baseline (32.9 vs. 20.9 %; p < 0.01). Partner disclosure needs to be better understood as a potential facilitator or barrier to microbicide adherence.  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