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   7847篇
  免费   395篇
  国内免费   66篇
耳鼻咽喉   54篇
儿科学   212篇
妇产科学   155篇
基础医学   857篇
口腔科学   228篇
临床医学   569篇
内科学   2062篇
皮肤病学   141篇
神经病学   633篇
特种医学   429篇
外科学   1261篇
综合类   23篇
预防医学   281篇
眼科学   58篇
药学   387篇
中国医学   10篇
肿瘤学   948篇
  2024年   10篇
  2023年   94篇
  2022年   146篇
  2021年   286篇
  2020年   171篇
  2019年   250篇
  2018年   312篇
  2017年   191篇
  2016年   215篇
  2015年   228篇
  2014年   338篇
  2013年   407篇
  2012年   590篇
  2011年   594篇
  2010年   319篇
  2009年   282篇
  2008年   485篇
  2007年   457篇
  2006年   415篇
  2005年   480篇
  2004年   405篇
  2003年   393篇
  2002年   333篇
  2001年   100篇
  2000年   104篇
  1999年   69篇
  1998年   89篇
  1997年   63篇
  1996年   51篇
  1995年   45篇
  1994年   36篇
  1993年   29篇
  1992年   34篇
  1991年   38篇
  1990年   31篇
  1989年   27篇
  1988年   19篇
  1987年   21篇
  1986年   21篇
  1985年   12篇
  1984年   12篇
  1983年   10篇
  1982年   7篇
  1981年   7篇
  1980年   6篇
  1979年   8篇
  1977年   5篇
  1974年   7篇
  1968年   5篇
  1966年   8篇
排序方式: 共有8308条查询结果,搜索用时 15 毫秒
11.
Cationic block copolymers spontaneously assemble via electrostatic interactions with DNA molecules in aqueous solution giving rise to micellar structures that protect the DNA from enzymatic degradation both in vitro and in vivo. In addition, we have previously shown that they are safe, not immunogenic and greatly increased antigen-specific CTL responses following six intramuscular inoculations of a very low dose (1 μg) of the vaccine DNA as compared to naked DNA. Nevertheless, they failed to elicit detectable humoral responses against the antigen. To gain further insight in the potential application of this technology, here we show that a shorter immunization protocol based on two DNA intramuscular inoculations of 1 μg of DNA delivered by these copolymers and a protein boost elicits in mice broad (both humoral and cellular) and long-lasting responses and increases the antigen-specific Th1-type T cell responses and CTLs as compared to priming with naked DNA. These results indicate that cationic block copolymers represent a promising adjuvant and delivery technology for DNA vaccination strategies aimed at combating intracellular pathogens.  相似文献   
12.
OBJECTIVE: To evaluate the dynamics of bacterial contamination of healthcare workers' (HCWs) hands during neonatal care. SETTING: The 20-bed neonatal unit of a large acute care teaching hospital in Geneva, Switzerland. METHODS: Structured observation sessions were conducted. A sequence of care began when the HCW performed hand hygiene and ended when the activity changed or hand hygiene was performed again. Alcohol-based handrub was the standard procedure for hand hygiene. An imprint of the five fingertips of the dominant hand was obtained before and after hand hygiene and at the end of a sequence of care. Regression methods were used to model the final bacterial count according to the type and duration of care and the use of gloves. RESULTS: One hundred forty-nine sequences of care were observed. Commensal skin flora comprised 72.4% of all culture-positive specimens (n = 360). Other microorganisms identified were Enterobacteriaceae (n = 55, 13.8%); Staphylococcus aureus (n = 10, 2.5%); and fungi (n = 7, 1.8%). Skin contact, respiratory care, and diaper change were independently associated with an increased bacterial count; the use of gloves did not fully protect HCWs' hands from bacterial contamination. CONCLUSIONS: These data confirm that hands become progressively contaminated with commensal flora and potential pathogens during neonatal care, and identify activities at higher risk for hand contamination. They also reinforce the need for hand hygiene after a sequence of care, before starting a different task, and after glove removal.  相似文献   
13.
Benzo[a]pyrene diol epoxide adducts with hemoglobin (Hb) weremeasured to detect human exposure to environmental benzo[a]pyrenefrom traffic exhaust. Benzo[a]pyrene tetrahydrotetrols (BPTs)released from Hb after acid hydrolysis were quantitated by gaschromatography-mass spectrometry after immunoaffinity chromatography.Fifty three newspaper vendors were enrolled. The median adductconcentration was 0.3 fmol BPTs/mg Hb in high density traffic-exposedvendors and  相似文献   
14.
15.
We investigated the neurophysiological and clinical effects of repetitive magnetic stimulation (rTMS) delivered to the cortical motor areas in healthy subjects and patients with Parkinson's disease. rTMS was delivered with a high speed magnetic stimulator (Cadwell, Kennewick, WA) through a figure-eight coil centred on the primary motor area at a stimulus intensity of 120% motor threshold. Trains of 10 stimuli were delivered at frequencies of 5 Hz while subjects were at rest and during a voluntary contraction of the contralateral first dorsal interosseous muscle. In normal subjects at rest, the muscle evoked responses (MEPs) to each stimulus in a train of magnetic stimuli progressively increased in size during the train. rTMS left the MEPs unchanged in patients off therapy and had a small facilitatory effect in those on therapy. In normal subjects and patients, 5-Hz rTMS trains delivered during a voluntary contraction of the target muscle left the MEP unchanged in size. MEPs were followed by a silent period that increased in duration during the course of the train. The silent period duration increased to a similar extent in patients and controls. The reduced rTMS-induced facilitation of MEPs in patients with Parkinson's disease reflects a decreased facilitation of the excitatory cells in the cortical motor areas.  相似文献   
16.
The epidemiological burden of diabetes mellitus is changing the classical model of diabetes management, in which a specialist center delivers care based on registration, recall and regular review. Primary care services are progressively assuming a crucial role in screening, prevention and management of the disease. It therefore becomes critical to improve the performance of primary care providers by suitable organizational interventions. The current advances in information technology (IT) and communications technology provide new ways for coping with organizational problems, and provide the opportunity to implement complex, multifaceted interventions in a cost-effective manner. Moreover, IT enables patients to exploit new modalities of access to healthcare services.This review highlights the current situation in the implementation and delivery of IT solutions for diabetes care, and describes the trends towards more advanced and innovative IT-based services.A large number of electronic patient records (EPRs), decision support tools and telemedicine solutions have been proposed and studied but a relatively low number of them have been fully exploited in clinical practice. The main reasons for this limited dissemination are related to the complexity of establishing and evaluating interventions that have a strong impact in the process of care. However, the need for a large scale reorganization of chronic care is now pushing towards the integration of the newest IT tools with new models of diabetes management.  相似文献   
17.
The alpha subunit of the nicotinic acetylcholine receptor (AChR) seems crucial in the pathogenesis of the autoimmune paralysis myasthenia gravis (MG) because it contains both the epitopes that dominate the antibody response against the AChR and those recognized by CD4+ AChR-specific T helper (Th) cells. To define the repertoire of anti-AChR Th cells, we investigated the response of unselected blood CD4+ cells or total lymphocytes, or both, from 22 MG patients to 20-residue overlapping synthetic peptides, screening the complete sequence of human-muscle AChR alpha subunit. Several epitopes were identified. Only the most severely affected patients recognized alpha subunit epitopes, and they were mainly young women. Detection of in vitro AChR-specific CD4+ response was facilitated by removal of the CD8+ cells because in two patients a clear response to several alpha subunit peptide sequences could be detected when CD(8+)-depleted cells were used, while their total peripheral blood mononuclear cell population did not respond to any alpha subunit peptide. Although each patient had a unique pattern of peptide recognition, four immunodominant regions recognized by long-term AChR-specific CD4+ T-cell lines, or flanking peptide sequences, were recognized most frequently (residues 48-67, 101-137, 293-337, and 308-437).  相似文献   
18.
Contact diode laser myringotomy and mitomycin C in children   总被引:1,自引:0,他引:1  
OBJECTIVE: To investigate the use of contact diode laser myringotomy (C-LAM), combined with topical mitomycin C, as an alternative method for prolonged middle ear ventilation in children with otitis media with effusion. STUDY DESIGN AND SETTING: Prospective study at a tertiary care pediatric institution. METHODS: Fifteen children enrolled in the study. Mitomycin C was applied to the intact tympanic membrane in the right ears, whereas saline on the left side was used for controls. C-LAM was then performed in all ears. Outcome measures included healing rate and scarring, ear infection, and long-term audiometric follow-up. RESULTS: There was no significant difference in median healing rate. In each group, the median was between the third and fourth month. Normal hearing thresholds were obtained in all children at 2-year follow-up. CONCLUSION: C-LAM proved to be an effective method for medium-term ventilation, but topical mitomycin C before C-LAM did not prolong patency rate in our patients. No significant complication was encountered at 2-year follow-up.  相似文献   
19.
20.
The urinary excretion of polyamines was evaluated before, during and after radiotherapy in 16 patients with advanced squamous cell carcinoma of the uterine cervix (stage IIb or IIIb) and in 7 cases with pelvic recurrence after surgery for various types of carcinoma. The concentration of spermidine was significantly higher in the patients with primary tumors than in those with recurrent tumors. After the first radiation fractions putrescine increased in the patients with primary tumors whereas it decreased in patients with recurrent tumors. The values tended to return to baseline levels with time following treatment initiation. Polyamine increased markedly during treatment in patients who remained disease-free for at least 5 years but not in the patients with progressive disease or relapse. The results suggest a different polyamine metabolism and a different response to radiotherapy of recurrent tumors compared to primary tumors. The increase of urinary polyamines, but not the baseline values, seemed to be correlated to the response after radiotherapy.  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