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   12078篇
  免费   1742篇
  国内免费   23篇
耳鼻咽喉   207篇
儿科学   353篇
妇产科学   230篇
基础医学   1855篇
口腔科学   224篇
临床医学   1360篇
内科学   2316篇
皮肤病学   141篇
神经病学   995篇
特种医学   499篇
外国民族医学   1篇
外科学   1553篇
综合类   869篇
一般理论   8篇
预防医学   1460篇
眼科学   172篇
药学   882篇
  1篇
中国医学   26篇
肿瘤学   691篇
  2021年   135篇
  2020年   119篇
  2019年   186篇
  2018年   244篇
  2017年   164篇
  2016年   146篇
  2015年   204篇
  2014年   258篇
  2013年   378篇
  2012年   575篇
  2011年   580篇
  2010年   347篇
  2009年   310篇
  2008年   518篇
  2007年   507篇
  2006年   506篇
  2005年   475篇
  2004年   508篇
  2003年   465篇
  2002年   438篇
  2001年   414篇
  2000年   475篇
  1999年   390篇
  1998年   214篇
  1997年   150篇
  1996年   169篇
  1995年   160篇
  1994年   158篇
  1993年   123篇
  1992年   292篇
  1991年   303篇
  1990年   257篇
  1989年   298篇
  1988年   244篇
  1987年   268篇
  1986年   241篇
  1985年   242篇
  1984年   223篇
  1983年   185篇
  1982年   162篇
  1981年   107篇
  1980年   79篇
  1979年   176篇
  1978年   129篇
  1977年   117篇
  1976年   104篇
  1974年   103篇
  1973年   99篇
  1972年   81篇
  1971年   73篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
102.
A human chromosomal translocation t(8;9) was detected using two-color fluorescence in situ hybridization with probes capable of staining the entire lengths of each of these chromosomes. The chromosome 8 probe was labeled with biotin and detected with Texas red, while the chromosome 9 probe was labeled with AAF and detected with FITC . In normal metaphase spreads, two metaphases from the proband, two red, one green and one part red and part green derivative chromosome were seen. The bicolor chromosome corresponded to translocation of a chromosome 8 segment to the distal part of the q region of one chromosome 9, as originally indicated by banding analysis. In interphase nuclei of the proband, four domains with bright fluorescence were recognized in many nuclei. Two were red, one was green, and the fourth had portions of both colors, indicating the presence of the translocation.  相似文献   
103.
Ingestion of small bones often causes oropharyngeal trauma. I present an unusual case of a potentially life-threatening haematoma of the soft palate caused by a chicken bone. To my knowledge, this is the only case reported in the English literature.  相似文献   
104.
105.
Infectious intracavernous carotid artery aneurysms usually present with ophthalmoplegia and/or signs of cavernous sinus thrombosis. We report an unusual case in which a patient with AIDS presented with intractable epistaxis secondary to rupture of a giant infectious intra-cavernous carotid artery aneurysm. Culture of the aneurysm grew mycobacterium avium intracellulare (MAI). The patient was treated successfully by excision of the aneurysm and reconstruction of the internal carotid artery with a saphenous vein interposition graft.  相似文献   
106.
A group of investigators met at a Specialized Programs of Research Excellence Workshop to discuss key issues in the translation of biomarker discovery to the development of useful laboratory tests for cancer care. Development and approval of several new markers and technologies have provided informative examples that include more specific markers for prostate cancer, more sensitive tests for ovarian cancer, more objective analysis of tissue architecture and an earlier indication of response to treatment in breast cancer. Although there is no clear paradigm for biomarker development, several principles are clear. Marker development should be driven by clinical needs, including early cancer detection, accurate pretreatment staging, and prediction of response to treatment, as well as monitoring disease progression and response to therapy. Development of a national repository that uses carefully preserved, well-annotated tissue specimens will facilitate new marker development. Reference standards will be an essential component of this process. Both hospital-based and commercial laboratories can play a role in developing biomarkers from discovery to test validation. Partnering of academe and industry should occur throughout the process of biomarker development. The National Cancer Institute is in a unique position to bring together academe, industry, and the Food and Drug Administration to (a) define clinical needs for biomarkers by tumor type, (b) establish analytic and clinical paradigms for biomarker development, (c) discuss ways in which markers from different companies might be evaluated in combination, (d) establish computational methods to combine data from multiple biomarkers, (e) share information regarding promising markers developed in National Cancer Institute-supported programs, and (f) exchange data regarding new platforms and techniques that can accelerate marker development.  相似文献   
107.
A near-patient testing facility was provided at an anticonvulsant clinic and compared with the previously offered service. Productivity was increased by over 20%, with savings in medical and nursing staff time. This saving in time is offset by increased consumable costs but still enables a significant net saving.  相似文献   
108.
109.
Although natural family planning (NFP) is a form of contraception without ostensible maternal risks (other than pregnancy), potential fetal risks could exist if aging gametes are involved in inadvertent fertilization. In the following report, we first review animal studies firmly establishing that aging sperm and aging oocytes (delayed fertilization) cause chromosomal abnormalities in mammals and other species. We next review human studies associating decreased coital frequency with trisomy and studies of NFP populations that generally show no increased frequency of anomalous offspring or spontaneous abortions. Our rationale for initiating an international cohort study is presented, along with the experimental design selected. Preliminary findings indicate that the experimental design chosen will indeed provide information allowing NFP safety to be assessed definitively.
Resumen Aunque la planificación familiar natural (PFN) es una forma de anticoncepción sin riesgos maternos ostensibles, (fuera del embarzo) podrían existir posibles riesgos fetales di gametos que están envejeciendo son inadvertidamente fertilizados. La primera revisión de estudios en animales establece firmemente que espermatozoides y oocytos en envejecimiento (fertilización tardía), causan anormalidades cromosómicas en mamíferos y otras especies. A continuación revisamos estudios en humanos que asocian la disminución de la frecuencia coital con trisomía, y estudios de poblaciones practicando PFN que generalmente no muestran aumento en la frecuencia de descendientes anormales o de abortos espontáneos. Presentamos nuestras razones para iniciar el estudio de una cohorte internactional ademas del diseño experimental elegido proveerá información alegando que la inocuidad de la PFN sea definitivamente valorada.

Resumé Bien que le planning familial naturel (PFN-NFP) soit une forme de contraception ne présentant pas de risques manifestes pour la mère (autres qu'une grossesse), il pourrait y avoir des risques potentiels pour le foetus si des gamètes âgés sont par inadvertance fécondés. Nous passons en revue tout d'abord des études effectuées sur des animaux, établissant fermement que le sperme veillissant et les oocytes vieillissants (fécondation retardée) provoquent des anomalies chromosomales chez les mammifères et d'autres espèces. Nous examinons ensuite des études sur des humains, qui associent diminution coitale et trisomie, et des études de populations pratiquant le PFN, qui ne révèlent généralement pas de fréquence accrue d'enfants anormaux ou d'avortements spontanés. Cette communication expose la raison pour laquelle nous avons entrepris une étude sur une cohorte internationale, ainsi que le concept d'expérimentation que nous avons choisi. Les constatations préliminaires indiquent que ce concept fournira véritablement des informations qui permettront d'évaluer de façon définitive la sécurité du PFN.
  相似文献   
110.
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