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   599454篇
  免费   45273篇
  国内免费   16595篇
耳鼻咽喉   6417篇
儿科学   12380篇
妇产科学   13427篇
基础医学   77869篇
口腔科学   12153篇
临床医学   64354篇
内科学   112272篇
皮肤病学   8447篇
神经病学   45007篇
特种医学   20633篇
外国民族医学   110篇
外科学   80069篇
综合类   41937篇
现状与发展   48篇
一般理论   395篇
预防医学   44355篇
眼科学   15777篇
药学   50366篇
  170篇
中国医学   11924篇
肿瘤学   43212篇
  2023年   4523篇
  2022年   11110篇
  2021年   17435篇
  2020年   11963篇
  2019年   13615篇
  2018年   15196篇
  2017年   12353篇
  2016年   12561篇
  2015年   16993篇
  2014年   22709篇
  2013年   25637篇
  2012年   38351篇
  2011年   41108篇
  2010年   24172篇
  2009年   20480篇
  2008年   32107篇
  2007年   33275篇
  2006年   32639篇
  2005年   32390篇
  2004年   27319篇
  2003年   25049篇
  2002年   22943篇
  2001年   14342篇
  2000年   14184篇
  1999年   14010篇
  1998年   8331篇
  1997年   7428篇
  1996年   5826篇
  1995年   5484篇
  1994年   4710篇
  1993年   3803篇
  1992年   7076篇
  1991年   6778篇
  1990年   6075篇
  1989年   5799篇
  1988年   5496篇
  1987年   5190篇
  1986年   4830篇
  1985年   4542篇
  1984年   3660篇
  1983年   3225篇
  1982年   2527篇
  1981年   2297篇
  1980年   2086篇
  1979年   2826篇
  1978年   2066篇
  1975年   1742篇
  1974年   1942篇
  1973年   1904篇
  1972年   1772篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
目的探讨乙肝孕妇血清标志物模式、HBV-DNA载量及肝功能三者之间的关系,为孕期乙肝病毒感染情况的监控和乙肝病毒母婴传播的预防提供参考。方法选取2019年1月-11月在我院产检的767例乙肝表面抗原阳性孕妇的乙肝血清标志物模式、肝功能指标的丙氨酸氨基转移酶(alamine aminotransferase,ALT)及HBVDNA载量进行研究,探讨三者间的关系。结果HBsAg、HBeAg、HBcAb阳性组孕妇HBV-DNA阳性率及病毒载量均高于其余两组(P<0.05);ALT升高程度与HBV-DNA载量具有一定相关性(r=0.255,χ^2=80.150,P=0.000);HBeAg阳性组和HBeAg阴性组间HBV-DNA阳性率、ALT异常率差异均有统计学意义。结论HBV-M、HBV-DNA与肝功能之间有一定的相关性,大三阳孕妇中高病毒载量比例高,应加强乙肝孕妇孕期各项指标的监测,必要时进行干预治疗。  相似文献   
52.
AimsWe previously showed that the protective effects of endothelial progenitor cells (EPCs)‐released exosomes (EPC‐EXs) on endothelium in diabetes. However, whether EPC‐EXs are protective in diabetic ischemic stroke is unknown. Here, we investigated the effects of EPC‐EXs on diabetic stroke mice and tested whether miR‐126 enriched EPC‐EXs (EPC‐EXsmiR126) have enhanced efficacy.MethodsThe db/db mice subjected to ischemic stroke were intravenously administrated with EPC‐EXs 2 hours after ischemic stroke. The infarct volume, cerebral microvascular density (MVD), cerebral blood flow (CBF), neurological function, angiogenesis and neurogenesis, and levels of cleaved caspase‐3, miR‐126, and VEGFR2 were measured on day 2 and 14.ResultsWe found that (a) injected EPC‐EXs merged with brain endothelial cells, neurons, astrocytes, and microglia in the peri‐infarct area; (b) EPC‐EXsmiR126 were more effective than EPC‐EXs in decreasing infarct size and increasing CBF and MVD, and in promoting angiogenesis and neurogenesis as well as neurological functional recovery; (c) These effects were accompanied with downregulated cleaved caspase‐3 on day 2 and vascular endothelial growth factor receptor 2 (VEGFR2) upregulation till day 14.ConclusionOur results indicate that enrichment of miR126 enhanced the therapeutic efficacy of EPC‐EXs on diabetic ischemic stroke by attenuating acute injury and promoting neurological function recovery.  相似文献   
53.
54.
55.
56.
57.
Thermal ablation of liver tumors near large blood vessels is affected by the cooling effect of blood flow, leading to incomplete ablation. Hence, we conducted a comparative investigation of heat sink effect in monopolar (MP) and bipolar (BP) radiofrequency ablation (RFA), and microwave (MW) ablation devices.With a perfused calf liver, the ablative performances (volume, mass, density, dimensions), with and without heat sink, were measured. Heat sink was present when the ablative tip of the probes were 8.0 mm close to a major hepatic vein and absent when >30 mm away. Temperatures (T1 and T2) on either side of the hepatic vein near the tip of the probes, heating probe temperature (T3), outlet perfusate temperature (T4), and ablation time were monitored.With or without heat sink, BP radiofrequency ablated a larger volume and mass, compared with MP RFA or MW ablation, with latter device producing the highest density of tissue ablated. MW ablation produced an ellipsoidal shape while radiofrequency devices produced spheres.Percentage heat sink effect in Bipolar radiofrequency : Mono-polar radiofrequency : Microwave was (Volume) 33:41:22; (mass) 23:56:34; (density) 9.0:26:18; and (relative elipscity) 5.8:12.9:1.3, indicating that BP and MW devices were less affected.Percentage heat sink effect on time (minutes) to reach maximum temperature (W) = 13.28:9.2:29.8; time at maximum temperature (X) is 87:66:16.66; temperature difference (Y) between the thermal probes (T3) and the temperature (T1 + T2)/2 on either side of the hepatic vessel was 100:87:20; and temperature difference between the (T1 + T2)/2 and temperature of outlet circulating solution (T4), Z was 20.33:30.23:37.5.MW and BP radiofrequencies were less affected by heat sink while MP RFA was the most affected. With a single ablation, BP radiofrequency ablated a larger volume and mass regardless of heat sink.  相似文献   
58.
59.
60.
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