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   10342篇
  免费   1339篇
  国内免费   58篇
耳鼻咽喉   28篇
儿科学   185篇
妇产科学   114篇
基础医学   657篇
口腔科学   55篇
临床医学   987篇
内科学   1772篇
皮肤病学   85篇
神经病学   82篇
特种医学   115篇
外科学   708篇
综合类   1025篇
现状与发展   3篇
一般理论   1篇
预防医学   4780篇
眼科学   20篇
药学   556篇
中国医学   101篇
肿瘤学   465篇
  2024年   25篇
  2023年   198篇
  2022年   433篇
  2021年   591篇
  2020年   489篇
  2019年   438篇
  2018年   379篇
  2017年   348篇
  2016年   418篇
  2015年   546篇
  2014年   755篇
  2013年   862篇
  2012年   796篇
  2011年   797篇
  2010年   619篇
  2009年   540篇
  2008年   493篇
  2007年   498篇
  2006年   407篇
  2005年   309篇
  2004年   245篇
  2003年   242篇
  2002年   158篇
  2001年   139篇
  2000年   131篇
  1999年   100篇
  1998年   101篇
  1997年   98篇
  1996年   91篇
  1995年   70篇
  1994年   94篇
  1993年   43篇
  1992年   42篇
  1991年   41篇
  1990年   33篇
  1989年   30篇
  1988年   31篇
  1987年   23篇
  1986年   30篇
  1985年   10篇
  1984年   10篇
  1983年   5篇
  1982年   9篇
  1981年   6篇
  1980年   3篇
  1979年   4篇
  1977年   2篇
  1974年   2篇
  1969年   1篇
  1967年   1篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
61.
62.
Bacteria of the genus Acinetobacter are ubiquitous in nature. These organisms were invariably susceptible to many antibiotics in the 1970s. Since that time, acinetobacters have emerged as multiresistant opportunistic nosocomial pathogens. The taxonomy of the genus Acinetobacter underwent extensive revision in the mid-1980s, and at least 32 named and unnamed species have now been described. Of these, Acinetobacter baumannii and the closely related unnamed genomic species 3 and 13 sensu Tjernberg and Ursing (13TU) are the most relevant clinically. Multiresistant strains of these species causing bacteraemia, pneumonia, meningitis, urinary tract infections and surgical wound infections have been isolated from hospitalised patients worldwide. This review provides an overview of the antimicrobial susceptibilities of Acinetobacter spp. in Europe, as well as the main mechanisms of antimicrobial resistance, and summarises the remaining treatment options for multiresistant Acinetobacter infections.  相似文献   
63.
Bacterial resistance to antibiotics in community-acquired respiratory tract infections is a serious problem and is increasing in prevalence world-wide at an alarming rate. Streptococcus pneumoniae , one of the main organisms implicated in respiratory tract infections, has developed multiple resistance mechanisms to combat the effects of most commonly used classes of antibiotics, particularly the β -lactams (penicillin, aminopenicillins and cephalosporins) and macrolides. Furthermore, multidrug-resistant strains of S. pneumoniae have spread to all regions of the world, often via resistant genetic clones. A similar spread of resistance has been reported for other major respiratory tract pathogens, including Haemophilus influenzae , Moraxella catarrhalis and Streptococcus pyogenes . To develop and support resistance control strategies it is imperative to obtain accurate data on the prevalence, geographic distribution and antibiotic susceptibility of respiratory tract pathogens and how this relates to antibiotic prescribing patterns. In recent years, significant progress has been made in developing longitudinal national and international surveillance programs to monitor antibiotic resistance, such that the prevalence of resistance and underlying trends over time are now well documented for most parts of Europe, and many parts of Asia and the Americas. However, resistance surveillance data from parts of the developing world (regions of Central America, Africa, Asia and Central/Eastern Europe) remain poor. The quantity and quality of surveillance data is very heterogeneous; thus there is a clear need to standardize or validate the data collection, analysis and interpretative criteria used across studies. If disseminated effectively these data can be used to guide empiric antibiotic therapy, and to support—and monitor the impact of—interventions on antibiotic resistance.  相似文献   
64.
As part of the Polish external quality assurance scheme, clinical laboratories were asked to send five consecutive isolates of Staphylococcus aureus and the corresponding susceptibility results to the national Centre of Quality Control in Microbiology. Of 1376 isolates submitted as S. aureus from 276 medical centres, 13 (< 1%) had been misidentified by local laboratories. Of 181 (13.5%) methicillin-resistant S. aureus (MRSA) isolates, most were identified correctly (c. 98% of laboratories). Although all MRSA isolates were fully susceptible to vancomycin, teicoplanin and linezolid, they were usually multiresistant; almost 23% were resistant to seven antimicrobial agents. Most (> 90%) MSSA isolates were susceptible to the tested antibiotics, except penicillin (21% susceptible) and tetracycline (62.4% susceptible). In addition to evaluating the proficiency of testing by local laboratories, the study yielded valuable information regarding the susceptibility patterns of S. aureus isolates in Poland.  相似文献   
65.
Summary: An intrinsic (oncogene-driven) pathway and an extrinsic (microenvironment-driven) pathway connect inflammatory reactions and cancer. M2-polarized tumor-associated macrophages and the related myeloid-derived suppressor cells are key prototypic components of smoldering inflammation driving neoplastic progression. However, mononuclear phagocytes can exert anti-tumor activity by killing tumor cells and eliciting tissue disruptive reactions (M1), a likely scenario in the early phases of carcinogenesis of immunogenic tumors and following therapeutic intervention. Shifting the macrophage balance represents a viable therapeutic target. Herein, the 'macrophage balance' is discussed in the context of the apparent paradox of tumor promotion by innate immunity-driven inflammation and the seemingly opposed tumor surveillance by adaptive immune responses.  相似文献   
66.
Antibiotic resistance is an increasing global problem. Surveillance studies are needed to monitor resistance development, to guide local empirical therapy, and to implement timely and adequate countermeasures. To achieve this, surveillance studies must have standardised methodologies, be longitudinal, and cover a sufficiently large and representative population. However, many fall short of these requirements that define good surveillance studies. Moreover, current efforts are dispersed among many, mostly small, initiatives with different objectives. These studies must be tailored to the various reservoirs of antibiotic-resistant bacteria, such as hospitalised patients, nursing homes, the community, animals and food. Two studies that could serve as examples of tailored programmes are the European Antimicrobial Resistance Surveillance System (EARSS), which collects resistance data during the diagnosis of hospitalised patients, and the DANMAP programme, which collects data in the veterinary sector. As already noted by the WHO, genetic studies that include both the typing of isolates and the characterisation of resistance determinants are necessary to understand fully the spread and development of antibiotic resistance.  相似文献   
67.
浙江淳安小学生流行性癔病的心理社会因素探讨   总被引:1,自引:0,他引:1  
本文报告对前文所述文昌乡中心小学四个流行性癔病发病班137名学生进行了问卷调查,其中曾发病者36人(女31,男5)与未发病的45人(女38,男7)对照组进行比较。结果显示发病组 EPQ 测定 N 分(神经质)高,平时情绪消极,应对能力差,依赖性强,体质较差,关系密切同学中患病者多,害怕鬼神等特点,与对照组相比,均有显著性差异。  相似文献   
68.
The tribe Proteeae comprises the genera Proteus, Morganella and Providencia. Few studies have specifically investigated the epidemiology of infections caused by the Proteeae, and none has been conducted in a large non-selected population. The present study was a population-based laboratory surveillance in the Calgary Health Region (population 1.2 million), Canada during 2000-2005 that aimed to define the incidence, demographical risk-factors for acquisition and antimicrobial susceptibilities of Proteeae isolates. In total, 5047 patients were identified from whom Proteeae isolates were obtained (an annual incidence of 75.9/100 000), with females and the elderly being at highest risk. Incidence rates were 64.8, 7.7 and 3.4/100,000/year for the genera Proteus, Morganella and Providencia, respectively. Overall, 85% of infections were community-onset, and the overall rate of bacteraemic disease was 2.0/100,000. Compared with other species, Proteus mirabilis occurred at a much higher frequency, especially among females, and was less likely to be isolated from hospital-onset infections or to be part of a polymicrobial infection. Among isolates from community-onset infections, Providencia spp. were less likely to be from outpatients and more likely to be from nursing home residents. There were low overall rates of resistance to ciprofloxacin (4%) and gentamicin (5%), with Prot. mirabilis generally being the most susceptible. Members of the Proteeae were isolated frequently in both the community and hospital settings, but were infrequent causes of invasive disease. The occurrence, demographical risk-factors and microbiology of Proteeae isolates varied according to the individual species.  相似文献   
69.
During 2003, Australia and New Zealand experienced substantial outbreaks of influenza. The strain responsible was an A(H3N2) influenza virus described as A/Fujian/411/2002-like, which had circulated as a minor variant in the previous Northern Hemisphere (NH) winter, mainly in Korea and Japan. Early in the year the isolates were very similar to those that had been previously isolated in the NH, however, a reassortant strain emerged early in the New Zealand winter, followed by the appearance of similar viruses in Australia and other regional areas. While the hemagglutinin HA1 sequence of these viruses demonstrated only minor differences from the A/Fujian/411/2002 reference strain, the neuraminidase gene was clearly different from that of other recently circulating H3 viruses and most closely matched an earlier reference strain A/Chile/6416/2001. Three internal genes (NS, NP, M) in the reassortant viruses were also more closely related to the A/Chile/6416/2001 lineage. This reassortant A(H3) virus predominated in Australia and New Zealand in 2003 was also seen in Brazil and Malaysia during 2003 and was widespread in the United States and Europe during their 2003-04 winter. Interestingly most of the strains of A(H3) that were isolated at the beginning of the 2004 winter in Australia, did not have this earlier A/Chile/6416/2001-like neuraminidase but had a neuraminidase that was similar to that of the reference strain A/Fujian/411/2002. This was suggestive of the re-introduction of influenza A(H3) from other countries, however, there was still low level circulation of the reassortant virus in 2004 with isolates detected in Australia and Singapore.  相似文献   
70.
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