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   211545篇
  免费   16022篇
  国内免费   5071篇
耳鼻咽喉   2918篇
儿科学   5467篇
妇产科学   3378篇
基础医学   21887篇
口腔科学   6182篇
临床医学   19077篇
内科学   40018篇
皮肤病学   5206篇
神经病学   12268篇
特种医学   6520篇
外国民族医学   1篇
外科学   23216篇
综合类   22175篇
现状与发展   13篇
一般理论   36篇
预防医学   23910篇
眼科学   3854篇
药学   17598篇
  116篇
中国医学   9028篇
肿瘤学   9770篇
  2024年   556篇
  2023年   2209篇
  2022年   3238篇
  2021年   6040篇
  2020年   4492篇
  2019年   4526篇
  2018年   7123篇
  2017年   5626篇
  2016年   4905篇
  2015年   6765篇
  2014年   8025篇
  2013年   11176篇
  2012年   16584篇
  2011年   17565篇
  2010年   12111篇
  2009年   10002篇
  2008年   14066篇
  2007年   14350篇
  2006年   13036篇
  2005年   11804篇
  2004年   9685篇
  2003年   8737篇
  2002年   7876篇
  2001年   5610篇
  2000年   5664篇
  1999年   3886篇
  1998年   909篇
  1997年   730篇
  1996年   718篇
  1995年   577篇
  1994年   442篇
  1993年   418篇
  1992年   1417篇
  1991年   1178篇
  1990年   1048篇
  1989年   904篇
  1988年   760篇
  1987年   727篇
  1986年   727篇
  1985年   623篇
  1984年   465篇
  1983年   378篇
  1979年   356篇
  1975年   283篇
  1974年   321篇
  1973年   352篇
  1972年   305篇
  1971年   330篇
  1970年   297篇
  1969年   296篇
排序方式: 共有10000条查询结果,搜索用时 18 毫秒
31.
32.
33.
34.
35.
Pulmonary hypertension of the newborn (PHN) constitutes a critical condition with severe cardiovascular and neurological consequences. One of its main causes is hypoxia during gestation, and thus, it is a public health concern in populations living above 2500 m. Although some mechanisms are recognized, the pathophysiological facts that lead to PHN are not fully understood, which explains the lack of an effective treatment. Oxidative stress is one of the proposed mechanisms inducing pulmonary vascular dysfunction and PHN. Therefore, we assessed whether melatonin, a potent antioxidant, improves pulmonary vascular function. Twelve newborn sheep were gestated, born, and raised at 3600 meters. At 3 days old, lambs were catheterized and daily cardiovascular measurements were recorded. Lambs were divided into two groups, one received daily vehicle as control and another received daily melatonin (1 mg/kg/d), for 8 days. At 11 days old, lung tissue and small pulmonary arteries (SPA) were collected. Melatonin decreased pulmonary pressure and resistance for the first 3 days of treatment. Further, melatonin significantly improved the vasodilator function of SPA, enhancing the endothelial‐ and muscular‐dependent pathways. This was associated with an enhanced nitric oxide‐dependent and nitric oxide independent vasodilator components and with increased nitric oxide bioavailability in lung tissue. Further, melatonin reduced the pulmonary oxidative stress markers and increased enzymatic and nonenzymatic antioxidant capacity. Finally, these effects were associated with an increase of lumen diameter and a mild decrease in the wall of the pulmonary arteries. These outcomes support the use of melatonin as an adjuvant in the treatment for PHN.  相似文献   
36.
37.
目的 收集藿香正气汤的主要活性成分,通过分子对接及网络药理学探讨其防控新型冠状病毒肺炎(COVID-19)的有效成分及治疗机制。方法 通过基于配体-蛋白质相互作用的计算方法,以瑞德西韦为对照,探索藿香正气汤潜在治疗COVID-19的成分,并选出对接较好成分进行药理学机制预测,初探其药理学机制。结果 本研究筛选出5种与新冠病毒3CLpro结合能力强于瑞德西韦的小分子成分。网络药理学初步预测抗病毒途径可能是通过PI3K-Akt 信号通路影响病毒复制。结论 成分C1-C5与3CLpro结合良好,推测其可能是潜在的3CLpro的抑制剂,为抗病毒天然药物的开发提供了理论依据。  相似文献   
38.
39.

Objectives

To determine the incidence of incisional hernia (IH) in the extraction incision (EI) in colorectal resection for cancer. To analyze whether the location of the incision has any relationship with the incidence of hernias and whether mesh could be useful for prevention in high-risk patients.

Methods

Retrospective review of the colon and rectal surgery database from January 2015 to December 2016. Data were classified into 2 groups, transverse (TI) and midline incision (MI), and the latter was divided into 2 subgroups (mesh [MIM] and suture [MIS]). Patients were classified using the HERNIAscore. Hernias were diagnosed by clinical and/or CT examination.

Results

A total of 182 out of 210 surgical patients were included. After a median follow-up of 13.0 months, 39 IH (21.9%) were detected, 23 of which (13.4%) were in the EI; their frequency was lower in the TI group (3.4%) and in the MIM group (5.9%) than in the MIS group (29.5%; p = 0.007). The probability of developing IH in the MIS group showed an OR = 11.7 (95%CI: 3.3-42.0) compared to the TI group and 4.3 (IC 95%: 1.1-16.3) versus the MIM group.

Conclusions

The location of the incision is relevant to avoid incisional hernias. Transverse incisions should be used as the first option. When a midline incision is needed, a prophylactic mesh could be considered in high risk patients because it is safe and associated with low morbidity.  相似文献   
40.
Clinical Oral Investigations - The aim of this study was the analysis of WNT10A variants in seven families of probands with various forms of tooth agenesis and self-reported family history of...  相似文献   
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