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   34313篇
  免费   1158篇
  国内免费   158篇
耳鼻咽喉   270篇
儿科学   963篇
妇产科学   691篇
基础医学   3352篇
口腔科学   895篇
临床医学   2627篇
内科学   5920篇
皮肤病学   450篇
神经病学   2129篇
特种医学   1752篇
外国民族医学   104篇
外科学   4528篇
综合类   3924篇
现状与发展   72篇
一般理论   15篇
预防医学   2664篇
眼科学   968篇
药学   2494篇
  3篇
中国医学   277篇
肿瘤学   1531篇
  2023年   24篇
  2022年   50篇
  2021年   78篇
  2020年   65篇
  2018年   35篇
  2016年   72篇
  2015年   73篇
  2014年   193篇
  2013年   253篇
  2012年   3019篇
  2011年   3363篇
  2010年   1050篇
  2009年   1137篇
  2008年   3221篇
  2007年   3395篇
  2006年   4455篇
  2005年   3066篇
  2004年   2370篇
  2003年   2179篇
  2002年   1853篇
  2001年   1419篇
  2000年   1927篇
  1999年   797篇
  1998年   117篇
  1997年   65篇
  1996年   115篇
  1995年   69篇
  1994年   54篇
  1993年   57篇
  1992年   44篇
  1991年   39篇
  1990年   32篇
  1989年   19篇
  1988年   14篇
  1986年   16篇
  1984年   21篇
  1983年   19篇
  1982年   15篇
  1981年   16篇
  1980年   16篇
  1963年   24篇
  1960年   13篇
  1959年   82篇
  1958年   117篇
  1957年   95篇
  1956年   92篇
  1955年   76篇
  1954年   64篇
  1949年   33篇
  1948年   41篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
由中、德科学中心发起、浙江大学与德国柏林洪堡大学共同主办的中德外科及基础病理新进展研讨会于2004年4月20日~22日在浙江省杭州市举行。会议由浙江大学来茂德教授和德国Humboldt大学Dietel教授主持,中、德两国共23名病理学专家参加了此次高水准国际病理学会议。会议主要涉及WHO肿瘤新分类、第6版国际抗癌联盟(UICC)TNM分期以及SARS病研究等。会议促进了双方病理学界的交流,增进了友谊,为今后中、德两国病理学界的进一步交流、合作开创了新局面。  相似文献   
82.
Rett syndrome (RTT) is classically defined by meeting certain clinical diagnostic criteria. It affects mostly females, and one possible pathogenic mechanism was considered to involve mitochondrial function. This was based on the finding of ultrastructural alterations in the mitochondria and decreased respiratory chain enzyme activity. However, the principal etiology of RTT has since been found to be mutations in the MECP2 gene, which is located on the X chromosome. Molecular analysis has allowed the phenotype of MECP2 mutations to be broadened beyond RTT to include girls who have mild mental retardation, autism, and an Angelman syndrome phenotype, as well as males with severe encephalopathy. We present a girl with a previously described mutation in the MECP2 gene whose phenotype is of atypical RTT. She presented with hypotonia and developmental delay in infancy without a clear period of normal development. As part of her evaluation for hypotonia, a muscle biopsy and respiratory chain enzyme analysis showed a slight decrease in respiratory chain enzyme activity consistent with previous reports. This report supports broadening the phenotype of patients who should be considered for MECP2 mutation analysis to include cases of developmental delay and hypotonia without evidence of an initial period of normal development. Furthermore, it supports the hypothesis of an underlying secondary defect in energy metabolism contributing to the pathogenesis of RTT.  相似文献   
83.
It has been speculated that exposure to the chronic stress of racism contributes to the high rates of hypertension among African Americans. Social support may buffer the effects of stress on cardiovascular (CV) health by attenuating stress-induced CV responses that have been linked to hypertension. In this study we investigated the effects of racism and social support on CV reactivity in African American women. Participants showed greater increases in CV and emotional responses while responding and listening to racist provocation. Augmented blood pressure (BP) persisted through recovery following racial stress. Participants receiving no support showed the greatest increases in anger during racist provocation. No significant effects were seen for support on CV reactivity. These results provide some of the first evidence that interactive confrontation with racism elicits significant increases in CV reactivity and emotional distress. Furthermore, individuals receiving less support may be at greater risk for the potentially health-damaging effects of racial stress. These findings may have significant implications for the health of African Americans.  相似文献   
84.
The p44 gene of the agent of human granulocytic ehrlichiosis (aoHGE) encodes a 44-kDa major outer surface protein. A technique was developed for the typing of the aoHGE based on the PCR amplification of the p44 gene followed by a multiple restriction digest with HindIII, EcoRV, and AspI to generate restriction fragment length polymorphism patterns. Twenty-four samples of the aoHGE were collected from geographically dispersed sites in the United States and included isolates from humans, equines, canines, small mammals, and ticks. Six granulocytic ehrlichiosis (GE) types were identified. The GE typing method is relatively simple to perform, is reproducible, and is able to differentiate among the various isolates of granulocytic ehrlichiae in the United States. These characteristics suggest that this GE typing method may be an important epizootiological and epidemiological tool.  相似文献   
85.
PRIMARY OBJECTIVE: To show that socio-economically dependent cultural bias distorts results of the status quo method of estimating age at first menstruation. METHODS: Questionnaires asking for menstrual status and the recalled age at menarche were distributed to approximately 1000 Javanese girls who attended junior and senior high schools in Malang. Age of participants ranged from 11.98 to 18.89 years. Probit analysis was applied to the status quo data while average menarcheal age recalled by girls > or =16 year old was also calculated. t-test, F-test, ANOVA and chi2 tests were applied to test significance of differences between groups. MAIN OUTCOMES and RESULTS: Girls of low occupational status fathers (Group 1) had a probit average menarcheal age of 13.99 years (SD = 1.33, n = 524). Girls of medium occupational status fathers (Group 2), had a lower probit average menarcheal age (13.06 SD = 1.38, n = 315). Girls of fathers with the highest occupational score (Group 3) rarely reported premenarcheal status (less than 10% in all age groups studied) and the probit analysis of their reports yielded an unbelievable average of 9.61 (SD = 3.41, n = 157) years. Group 3 girls tend to report their menarcheal status incorrectly, probably due to a 'fashion' of appearing mature or to 'contagion' during filling out of a questionnaire. The recalled average menarcheal age of Group 3 females questioned when they were aged 16 years and above, yields an average that seems to be more reliable (12.74 years, SD = 1.41, n = 7), because at a fully postmenarcheal age there is no need to enhance one's status by falsely claiming maturity.  相似文献   
86.
Streptococcus pyogenes protein H (sph) is an immunoglobulin-binding protein present in the Mga regulon of certain M1 serotype isolates. Although sph is present in many strains, it is frequently not expressed. In this paper we show that protein H was highly expressed after bacteria were injected into the skin of mice and were recovered from the blood, kidney, or spleen at various times postinfection. The percentage of protein H-positive colonies increased with time, reaching 100% in the spleen and kidney within 24 to 72 h postinfection. The up-regulation of sph expression was also observed in a mga mutant.  相似文献   
87.
We report the isolation of Legionella pneumophila serogroup 4 from synovial tissue obtained from an 80-year-old female with chronic swelling of her right metacarpophalangeal joint. Synovial tissue infections caused by L. pneumophila are rare. Interestingly, this isolate was recovered from chocolate agar after 5 days of incubation.  相似文献   
88.
Cassell GD  Weitzman MD 《Virology》2004,327(2):206-214
Adeno-associated virus (AAV) replicates in the nucleus of infected cells, and therefore multiple nuclear import events are required for productive infection. We analyzed nuclear import of the viral Rep proteins and characterized a nuclear localization signal (NLS) in the C-terminus. We demonstrate that basic residues in this region constitute an NLS that is transferable and mediates interaction with the nuclear import receptor importin alpha in vitro. Mutant Rep proteins are predominantly cytoplasmic and are severely compromised for interactions with importin alpha, but retain their enzymatic functions in vitro. Interestingly, mutations of the NLS had significantly less effect on importin alpha interaction and replication in the context of Rep78 than when incorporated into the Rep68 protein. Together, our results demonstrate that a bipartite NLS exists in the shared part of Rep68 and Rep78, and suggest that an alternate entry mechanism may also contribute to nuclear localization of the Rep78 protein.  相似文献   
89.
The HIV/AIDS surveillance system in Japan, which began collecting data on the number of AIDS patients in 1984 and the number of HIV-infected persons in 1987, has played an important role in monitoring the trend and magnitude of Japan's HIV/AIDS epidemic and its distribution across various population subgroups. However, the system lacks any personal identifiers, making it impossible to eliminate duplication or to track cases for disease progression. It also does not permit the identification of the residence of HIV-infected persons because the residence of only the reporting physician is documented under the New Infectious Diseases Control Law, effective since April 1, 1999. The number of people with HIV/AIDS in Japan continues to grow. Among youth, sexually transmitted diseases, induced abortion, and sexual activities have shown a marked increase since the mid-1990s. Behavioral risk of infection for both injection drug users (IDUs) and men who have sex with men (MSM) remains alarmingly high. Accurate monitoring of infection rates is critical to the planning and evaluation of treatment, care and prevention programs. Japan should restructure its HIV/AIDS surveillance system to more accurately monitor the HIV/AIDS epidemic and related risk behaviors.  相似文献   
90.
Using a rabbit model of systemic infection, we show that it is possible to differentiate infections caused by Candida dubliniensis and other Candida species by detecting the antibody response mounted by the infected animals. These results confirm our previous observation in a patient with C. dubliniensis candidemia and suggest that detection of C. dubliniensis-specific antibodies is useful in the diagnosis of invasive candidiasis caused by this yeast.  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