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   4432307篇
  免费   364568篇
  国内免费   15416篇
耳鼻咽喉   60915篇
儿科学   141697篇
妇产科学   116310篇
基础医学   677196篇
口腔科学   123696篇
临床医学   404352篇
内科学   800802篇
皮肤病学   109038篇
神经病学   370057篇
特种医学   175143篇
外国民族医学   523篇
外科学   678591篇
综合类   132718篇
现状与发展   24篇
一般理论   2587篇
预防医学   366865篇
眼科学   105371篇
药学   312398篇
  23篇
中国医学   12554篇
肿瘤学   221431篇
  2021年   56227篇
  2020年   35815篇
  2019年   59038篇
  2018年   74745篇
  2017年   56716篇
  2016年   62929篇
  2015年   76012篇
  2014年   110582篇
  2013年   176178篇
  2012年   123338篇
  2011年   128633篇
  2010年   126510篇
  2009年   127577篇
  2008年   114434篇
  2007年   121984篇
  2006年   130131篇
  2005年   124959篇
  2004年   126214篇
  2003年   115802篇
  2002年   104530篇
  2001年   173457篇
  2000年   169264篇
  1999年   153556篇
  1998年   73318篇
  1997年   68694篇
  1996年   66783篇
  1995年   62444篇
  1994年   56376篇
  1993年   52396篇
  1992年   112046篇
  1991年   107734篇
  1990年   103055篇
  1989年   100250篇
  1988年   92075篇
  1987年   90197篇
  1986年   85276篇
  1985年   83594篇
  1984年   69325篇
  1983年   61183篇
  1982年   48441篇
  1981年   44982篇
  1980年   42194篇
  1979年   59079篇
  1978年   47430篇
  1977年   42100篇
  1976年   38924篇
  1975年   38760篇
  1974年   42694篇
  1973年   41159篇
  1972年   38499篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
101.
Abstract

Oocyte maturation defect is a challenging situation in the management of infertility, the etiology may be related to endocrine causes, protocols used in ovarian stimulation, oocyte intrinsic defects or procedures in embryology laboratory. We report three Mexican females in treatment for primary infertility with non-mature oocytes after ovary stimulation and oocyte capture in whom a genetic diagnosis of TUBB8-oocyte maturation defect was revealed by exome sequencing. Two couples achieved pregnancies though oocyte donation after establishing the genetic etiology. Our results expand the role of TUBB8-disorders in patients of non-Asian ethnicity. Oocyte maturation defects of monogenic origin are a growing group of disorders that endocrinologists and reproductive medicine specialists should be aware in order to provide referral to genetics for establish a correct and opportune diagnosis.  相似文献   
102.
Aims. Functional connectivity is providing new insights into the network nature of epilepsy with growing clinical applications. Our objective was to validate a novel magnetoencephalography‐based method to non‐invasively measure the epileptic network. Methods. We retrospectively identified pediatric and adult patients with refractory focal epilepsy who underwent pre‐surgical magnetoencephalography with subsequent intracranial electrographic monitoring. Magnetoencephalography tracings were visually reviewed, and interictal epileptiform discharges (“spikes”) were individually marked. We then evaluated differences in whole‐brain connectivity during brief epochs preceding the spikes and during the spikes using the Network‐Based Statistic to test differences at the network level. Results. In six patients with statistically‐significant network differences, we observed substantial overlap between the spike‐associated networks and electrographically active areas identified during intracranial monitoring (the spike‐associated network was 78% and 83% sensitive for intracranial electroencephalography‐defined regions in the irritative and seizure onset zones, respectively). Conclusion. These findings support the neurobiological validity of the spike‐associated network method. Assessment of spike‐associated networks has the potential to improve surgical planning in epilepsy surgery patients by identifying components of the epileptic network prior to implantation.  相似文献   
103.
104.
目的:探讨健脾益肾方对非小细胞肺癌(NSCLC)细胞体外增殖凋亡的作用。方法:人NSCLC细胞系A549分为四组:空白对照组(仅加入细胞培养液)、阴性对照组(加入细胞,不进行中药处理)、实验组(加细胞加中药处理)。荧光定量PCR和Western blot分别检测Survivin、Bcl-2和Caspase-3的mRNA和蛋白表达。MTT检测细胞增殖;流式细胞术检测细胞凋亡。结果:与空白对照组相比,阴性对照组细胞在24、48、72 h的吸光度值明显升高,细胞凋亡率下降,Survivin和Bcl-2 mRNA和蛋白相对表达量上调,Caspase-3 mRNA和蛋白相对表达量下调,组间比较差异有统计学意义(P<0.05);而健脾益肾方处理的实验组24、48、72 h的吸光度值均显著降低,细胞凋亡率显著上升,Survivin和Bcl-2 mRNA和蛋白相对表达量下调,Caspase-3 mRNA和蛋白相对表达量上调,与空白对照组相比差异有统计学意义(P<0.05)。结论:健脾益肾方可通过下调Survivin和Bcl-2、上调Caspase-3表达诱导NSCLC细胞凋亡,并抑制肿瘤细胞的增殖,进而抑制NSCLC的发展。  相似文献   
105.
106.
107.
Introduction: Percutaneous renal mass biopsy has evolved over the last decade with improvements on previous pitfalls including low tissue yield, high non-diagnostic rates, and complications. As understanding of tumor biology and natural history of renal cortical neoplasms has improved, percutaneous renal mass biopsy is poised to have an expanding role in an area characterized by individualized management and refined risk stratification.

Areas covered: This review summarizes the evolution of renal mass biopsy to its current state with respect to outcomes, indications, and clinical guidelines.

Expert opinion: With improved understanding of differential biological potential of renal cortical neoplasms combined with technical improvements in diagnostic yield and accuracy, utilization of renal mass biopsy is becoming an important adjunct to patient care in a broad range of clinical scenarios, including active surveillance, thermal ablation, and use of primary systemic therapy in localized and advanced settings.  相似文献   

108.
109.
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