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   3251700篇
  免费   270425篇
  国内免费   13753篇
耳鼻咽喉   44330篇
儿科学   104316篇
妇产科学   83378篇
基础医学   523480篇
口腔科学   87315篇
临床医学   293124篇
内科学   566737篇
皮肤病学   88504篇
神经病学   280022篇
特种医学   127673篇
外国民族医学   329篇
外科学   502690篇
综合类   100943篇
现状与发展   23篇
一般理论   2273篇
预防医学   275651篇
眼科学   73990篇
药学   221448篇
  23篇
中国医学   9339篇
肿瘤学   150290篇
  2021年   54879篇
  2020年   35047篇
  2019年   57981篇
  2018年   70855篇
  2017年   54072篇
  2016年   59653篇
  2015年   73772篇
  2014年   107960篇
  2013年   173288篇
  2012年   87325篇
  2011年   86921篇
  2010年   115481篇
  2009年   120157篇
  2008年   73888篇
  2007年   76198篇
  2006年   87298篇
  2005年   82487篇
  2004年   84878篇
  2003年   75881篇
  2002年   65579篇
  2001年   94883篇
  2000年   87413篇
  1999年   89070篇
  1998年   64380篇
  1997年   62436篇
  1996年   60193篇
  1995年   55730篇
  1994年   49990篇
  1993年   46565篇
  1992年   62671篇
  1991年   59768篇
  1990年   56865篇
  1989年   56279篇
  1988年   51887篇
  1987年   51283篇
  1986年   48400篇
  1985年   48873篇
  1984年   45449篇
  1983年   41732篇
  1982年   40753篇
  1981年   38553篇
  1980年   36255篇
  1979年   37215篇
  1978年   33848篇
  1977年   31047篇
  1976年   28550篇
  1975年   26868篇
  1974年   27668篇
  1973年   26647篇
  1972年   24728篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
A case of cyclobenzaprine (flexeril) overdose and the resultant rhabdomyolysis is presented. A review of the range of clinical toxicity, management of overdose is described. The similarity of cyclobenzaprine to the tricyclic antidepressant class is emphasized; this report attempts to disseminate related information on this commonly prescribed centrally acting muscle relaxant.  相似文献   
993.
994.
Opportunistic infections in the oral cavity of the elderly may increase the incidence of systemic disease. The objective of this study was to investigate the differences in the oral bacterial flora between dependent elderly (inpatients) and independent elderly (community-dwelling residents). After multiple variables were taken into account, inpatients had significantly lower detection rates than community-dwelling residents for alpha-streptococci (p < 0.001) and Neisseria (p 0.004), and higher detection rates for Pseudomonas aeruginosa (p 0.024), methicillin-resistant Staphylococcus aureus (MRSA) (p 0.011) and Actinomyces spp. (p 0.005). Among inpatients, the requirement for a high degree of care was related negatively to detection of alpha-streptococci, but was related significantly to detection of P. aeruginosa (p 0.018) or MRSA (p 0.004). Tube-fed inpatients had a significantly lower detection rate for alpha-streptococci (p 0.041) and a higher detection rate for P. aeruginosa (p 0.004) than those who did not require tube feeding. Inpatients with a history of antibiotic use had a significantly lower detection rate for alpha-streptococci (p 0.049) and a higher detection rate for MRSA (p 0.007) than those without a history of antibiotic use. The detection rates for P. aeruginosa or MRSA in inpatients without alpha-streptococci were higher than in inpatients with alpha-streptococci after controlling for age and gender (P. aeruginosa, p 0.006; MRSA, p 0.001). Overall, detection of alpha-streptococci had an inverse correlation with the detection of P. aeruginosa and MRSA in the oral cavity and is likely to be an indicator of pathogenic bacterial infection.  相似文献   
995.
CXCL12 and its receptor, CXCR4, are emerging as promising targets for modulating growth, angiogenesis, and metastasis in several human cancers. Indeed, blocking the receptor is sufficient to prevent metastasis and angiogenesis in experimental breast cancer xenografts. Recently, the biological effect of the CXCR4 in pancreatic cancer, one of the most deadly neoplastic diseases, has been reported. However, the molecular mechanism by which CXCR4 contributes to these properties is not completely understood. In this paper, we characterize the signaling pathways activated by CXCR4 in pancreatic cancer. We show that after CXCR4 activation, EGFR becomes tyrosine phosphorylated, and the kinase activity of this receptor, together with the activation of MMPs, Src, and PI3-Kinase, is required for CXCR4-mediated ERK activation. Analysis of this cascade in pancreatic cancer cells revealed that the ERK-mediated pathway regulates genes involved in angiogenesis, such as VEGF, CD44, HIF1α, and IL-8. Furthermore, ERK blockage inhibits the migration and tube formation of endothelial cells induced by CXCL12. Considering that inhibitors for several components of this pathway, including CXCR4 itself, are at different stages of clinical trials, this study provides theoretical justification for the clinical testing of these drugs in pancreatic cancer, thus extending the list of potential targets for treating this dismal disease.  相似文献   
996.
Abstract: Background: Few studies have examined in depth the labor progression of multiparas to determine if there is any additional impact of being parous beyond the first birth. The objective of this study was to determine the effect of parity on labor progression in contemporary obstetric practice. Methods: Our sample consisted of all low‐risk women who delivered a term, live‐born infant from January 2002 to March 2004 at a single institution in Delaware, United States (n = 5,589). The median duration of labor by each centimeter of cervical dilation was computed for parity = 0 (n = 2,645); parity = 1 (n = 1,839); parity = 2 (n = 750); and parity = 3 + (n = 355). Results: Multiparas had a significantly faster labor progression from 4 to 10 cm (293, 300, and 313 min, respectively, for parity = 1, parity = 2, and parity = 3 +), compared with nulliparas (383 min for parity = 0), as well as a shorter second stage of labor. However, no significant differences were found in duration of the active phase or the second stage of labor among multiparas. Conclusions: Additional childbearing appears to have no effect of on the progression of labor among multiparous subgroups. The difference in duration of the active phase between nulliparas and multiparas is substantially smaller in a contemporary population. (BIRTH 33:1 March 2006)  相似文献   
997.
In order to assess the state and pathology of the woman's pelvis minor, a number of methods are commonly used among practitioners, encompassing clinical exploration, radiology, MRN, urodynamics, endoscopy and echography.

Echography has been poorly used in clinical pelvic exploration and its reliability is actually a matter of controversy 1. However, echographic surveys can provide us with valuable gynecological data on the state and pathologies of the soft pelvis, within the genital regions or even going beyond them, i.e. the rectal channel, bladder, urethra, anus, vascular plexuses, and all of their supporting tissues.

At our research unit, we have been employing Transvaginal Ultrasound echography (TVU) for a long time in conjunction with other pelvis-focused methods in order to study different kinds of pelvic alterations. TVU has proven to be friendly to use, fast, harmless and inexpensive, allowing serial explorations and producing high-quality dynamic images (loop-cinema, video-tape). Furthermore, this method is fairly aseptic in that the occurrence of faeces in the rectal ampolla is not a nuisance but a bonus in tracking the contours of the rectum walls and other topographical features which would be otherwise difficult to survey.

A complete pelvic floor TVU may add no longer than 5-8 minutes to a routine gynecological examination, can be implemented by the general gynecologist and generates data that can be further studied by the appropriate specialist for a more insightful evaluation 2.  相似文献   
998.
999.
Maternal and Child Health Journal -  相似文献   
1000.
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