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   515955篇
  免费   33759篇
  国内免费   3923篇
耳鼻咽喉   7192篇
儿科学   10569篇
妇产科学   12329篇
基础医学   74229篇
口腔科学   15192篇
临床医学   43399篇
内科学   103606篇
皮肤病学   12334篇
神经病学   39121篇
特种医学   21390篇
外国民族医学   83篇
外科学   78192篇
综合类   11112篇
现状与发展   4篇
一般理论   114篇
预防医学   25865篇
眼科学   12911篇
药学   43142篇
  3篇
中国医学   3571篇
肿瘤学   39279篇
  2022年   3870篇
  2021年   7123篇
  2020年   3842篇
  2019年   5811篇
  2018年   8274篇
  2017年   6468篇
  2016年   7475篇
  2015年   9523篇
  2014年   12209篇
  2013年   15302篇
  2012年   21730篇
  2011年   21636篇
  2010年   12636篇
  2009年   11445篇
  2008年   17534篇
  2007年   18136篇
  2006年   17378篇
  2005年   16103篇
  2004年   14808篇
  2003年   13842篇
  2002年   12921篇
  2001年   30419篇
  2000年   30745篇
  1999年   25355篇
  1998年   6187篇
  1997年   5038篇
  1996年   4467篇
  1995年   4105篇
  1994年   3640篇
  1993年   3314篇
  1992年   16936篇
  1991年   15761篇
  1990年   15031篇
  1989年   14685篇
  1988年   13294篇
  1987年   12727篇
  1986年   11706篇
  1985年   10961篇
  1984年   7437篇
  1983年   6012篇
  1982年   3034篇
  1979年   5892篇
  1978年   3683篇
  1977年   3267篇
  1975年   2914篇
  1974年   3391篇
  1973年   3137篇
  1972年   3103篇
  1971年   3008篇
  1969年   2736篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
92.
Russell-Silver syndrome (RSS) is a congenital disease characterized by short stature due to growth hormone deficiency, physical asymmetry, inverted triangular face, micrognathia, prominent forehead, and hypodontia. This case report presents a prosthetic management of a 6-year-old patient with Russell-Silver syndrome treated with overdentures on the maxilla and the mandible using the remaining primary teeth. Subsequent and comprehensive dental management considering the growth and development of a young patient will be necessary.  相似文献   
93.
Fluid is usually restricted during thoracic surgery, and vasoactive agents are often administered to maintain blood pressure. One-lung ventilation (OLV) decreases arterial oxygenation; thus oxygen delivery to the brain can be decreased. In this study, we compared phenylephrine and dopamine with respect to maintaining cerebral oxygenation during OLV in major thoracic surgery.Sixty-three patients undergoing lobectomies were randomly assigned to the dopamine (D) or phenylephrine (P) group. The patients’ mean arterial pressure was maintained within 20% of baseline by a continuous infusion of dopamine or phenylephrine. Maintenance fluid was kept at 5 mL/kg/h. The depth of anesthesia was maintained with desflurane 1MAC and remifentanil infusion under bispectral index guidance. Regional cerebral oxygen saturation (rScO2) and hemodynamic variables were recorded using near-infrared spectroscopy and esophageal cardiac Doppler.The rScO2 was higher in the D group than the P group during OLV (OLV 60 min: 71 ± 6% vs 63 ± 12%; P = 0.03). The number of patients whose rScO2 dropped more than 20% from baseline was 0 and 6 in the D and P groups, respectively (P = 0.02). The D group showed higher cardiac output, but lower mean arterial pressure than the P group (4.7 ± 1.0 vs 3.9 ± 1.2 L/min; 76.7 ± 8.1 vs 84.5 ± 7.5 mm Hg; P = 0.02, P = 0.02). Among the variables, age, hemoglobin concentration, and cardiac output were associated with rScO2 by correlation analysis.Dopamine was superior to phenylephrine in maintaining cerebral oxygenation during OLV in thoracic surgery.  相似文献   
94.
The growth of online support groups has led to an expression effects paradigm within the health communication literature. Although religious support expression is characterized as a typical subdimension of emotional support, we argue that in the context of a life-threatening illness, the inclusion of a religious component creates a unique communication process. Using data from an online group for women with breast cancer, we test a theoretical expression effects model. Results demonstrate that for breast cancer patients, religious support expression has distinct effects from general emotional support messages, which highlights the need to further theorize expression effects along these lines.  相似文献   
95.
96.
The developing CNS is exposed to physiological hypoxia, under which hypoxia-inducible factor α (HIFα) is stabilized and plays a crucial role in regulating neural development. The cellular and molecular mechanisms of HIFα in developmental myelination remain incompletely understood. A previous concept proposes that HIFα regulates CNS developmental myelination by activating the autocrine Wnt/β-catenin signaling in oligodendrocyte progenitor cells (OPCs). Here, by analyzing a battery of genetic mice of both sexes, we presented in vivo evidence supporting an alternative understanding of oligodendroglial HIFα-regulated developmental myelination. At the cellular level, we found that HIFα was required for developmental myelination by transiently controlling upstream OPC differentiation but not downstream oligodendrocyte maturation and that HIFα dysregulation in OPCs but not oligodendrocytes disturbed normal developmental myelination. We demonstrated that HIFα played a minor, if any, role in regulating canonical Wnt signaling in the oligodendroglial lineage or in the CNS. At the molecular level, blocking autocrine Wnt signaling did not affect HIFα-regulated OPC differentiation and myelination. We further identified HIFα–Sox9 regulatory axis as an underlying molecular mechanism in HIFα-regulated OPC differentiation. Our findings support a concept shift in our mechanistic understanding of HIFα-regulated CNS myelination from the previous Wnt-dependent view to a Wnt-independent one and unveil a previously unappreciated HIFα–Sox9 pathway in regulating OPC differentiation.SIGNIFICANCE STATEMENT Promoting disturbed developmental myelination is a promising option in treating diffuse white matter injury, previously called periventricular leukomalacia, a major form of brain injury affecting premature infants. In the developing CNS, hypoxia-inducible factor α (HIFα) is a key regulator that adapts neural cells to physiological and pathologic hypoxic cues. The role and mechanism of HIFα in oligodendroglial myelination, which is severely disturbed in preterm infants affected with diffuse white matter injury, is incompletely understood. Our findings presented here represent a concept shift in our mechanistic understanding of HIFα-regulated developmental myelination and suggest the potential of intervening with an oligodendroglial HIFα-mediated signaling pathway to mitigate disturbed myelination in premature white matter injury.  相似文献   
97.
98.
99.
100.
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