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   42652篇
  免费   2814篇
  国内免费   987篇
耳鼻咽喉   112篇
儿科学   648篇
妇产科学   331篇
基础医学   5810篇
口腔科学   762篇
临床医学   3248篇
内科学   4727篇
皮肤病学   264篇
神经病学   3827篇
特种医学   1072篇
外国民族医学   2篇
外科学   1567篇
综合类   3351篇
现状与发展   2篇
预防医学   4434篇
眼科学   161篇
药学   10953篇
  12篇
中国医学   3685篇
肿瘤学   1485篇
  2024年   83篇
  2023年   618篇
  2022年   970篇
  2021年   1538篇
  2020年   1404篇
  2019年   1405篇
  2018年   1391篇
  2017年   1455篇
  2016年   1345篇
  2015年   1262篇
  2014年   2271篇
  2013年   3509篇
  2012年   2047篇
  2011年   2451篇
  2010年   1597篇
  2009年   1892篇
  2008年   1833篇
  2007年   1852篇
  2006年   1584篇
  2005年   1384篇
  2004年   1201篇
  2003年   1064篇
  2002年   928篇
  2001年   893篇
  2000年   684篇
  1999年   678篇
  1998年   673篇
  1997年   590篇
  1996年   568篇
  1995年   541篇
  1994年   461篇
  1993年   449篇
  1992年   454篇
  1991年   415篇
  1990年   388篇
  1989年   393篇
  1988年   353篇
  1987年   343篇
  1986年   326篇
  1985年   445篇
  1984年   401篇
  1983年   282篇
  1982年   354篇
  1981年   276篇
  1980年   285篇
  1979年   209篇
  1978年   221篇
  1977年   159篇
  1976年   194篇
  1975年   79篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
32.
Malaria, one of the most striking, re-emerging infectious diseases caused by the genus Plasmodium, places a huge burden on global healthcare systems. A major challenge in the control and eradication of malaria is the continuous emergence of increasingly widespread drug-resistant malaria, creating an urgent need to develop novel antimalarial agents. Chalcone derivatives are ubiquitous in nature and have become indispensable units in medicinal chemistry applications due to their diverse biological profiles. Many chalcone derivatives demonstrate potential in vitro and in vivo antimalarial activity, so chalcone could be a useful template for the development of novel antimalarial agents. This review covers the recent development of chalcone hybrids as antimalarial agents. The critical aspects of the design and structure–activity relationship of these compounds are also discussed.  相似文献   
33.
The baroreflex is a critical physiological mechanism controlling cardiovascular function by modulating both the sympathetic and parasympathetic activities. Here, we report that electrical activation of the baroreflex attenuates joint inflammation in experimental arthritis induced by the administration of zymosan into the femorotibial cavity. Baroreflex activation combined with lumbar sympathectomy, adrenalectomy, celiac subdiaphragmatic vagotomy or splenectomy dissected the mechanisms involved in the inflammatory modulation, highlighting the role played by sympathetic inhibition in the attenuation of joint inflammation. From the immunological standpoint, baroreflex activation attenuates neutrophil migration and the synovial levels of inflammatory cytokines including TNF, IL-1β and IL-6, but does not affect the levels of the anti-inflammatory cytokine IL-10. The anti-inflammatory effects of the baroreflex system are not mediated by IL-10, the vagus nerve, adrenal glands or the spleen, but by the inhibition of the sympathetic drive to the knee. These results reveal a novel physiological neuronal network controlling peripheral local inflammation.  相似文献   
34.
《药学学报(英文版)》2020,10(7):1294-1308
A great challenge in multi-targeting drug discovery is to identify drug-like lead compounds with therapeutic advantages over single target inhibitors and drug combinations. Inspired by our previous efforts in designing antitumor evodiamine derivatives, herein selective histone deacetylase 1 (HDAC1) and topoisomerase 2 (TOP2) dual inhibitors were successfully identified, which showed potent in vitro and in vivo antitumor potency. Particularly, compound 30a was orally active and possessed excellent in vivo antitumor activity in the HCT116 xenograft model (TGI = 75.2%, 150 mg/kg, p.o.) without significant toxicity, which was more potent than HDAC inhibitor vorinostat, TOP inhibitor evodiamine and their combination. Taken together, this study highlights the therapeutic advantages of evodiamine-based HDAC1/TOP2 dual inhibitors and provides valuable leads for the development of novel multi-targeting antitumor agents.  相似文献   
35.
36.
Context: We sought to describe our experience with the Hybrid Assistive Limb® (HAL®) for active knee extension and voluntary ambulation with remaining muscle activity in a patient with complete paraplegia after spinal cord injury.

Findings: A 30-year-old man with complete paraplegia used the HAL® for 1 month (10 sessions) using his remaining muscle activity, including hip flexor and upper limb activity. Electromyography was used to evaluate muscle activity of the gluteus maximus, tensor fascia lata, quadriceps femoris, and hamstring muscles in synchronization with the Vicon motion capture system. A HAL® session included a knee extension session with the hip flexor and voluntary gait with upper limb activity. After using the HAL® for one month, the patient’s manual muscle hip flexor scores improved from 1/5 to 2/5 for the right and from 2/5 to 3/5 for the left knee, and from 0/5 to 1/5 for the extension of both knees.

Conclusion/clinical relevance: Knee extension sessions with HAL®, and hip flexor and upper-limb-triggered HAL® ambulation seem a safe and feasible option in a patient with complete paraplegia due to spinal cord injury.  相似文献   

37.
合理使用抗菌药物不仅能有力保护人类珍贵的药物资源,而且可促进感染病患者的规范诊治与健康。患者之间、病原菌之间、感染病之间及抗菌药物之间均存在明显差异,抗菌药物个体化治疗是合理用药的必由之路,关注感染病诊治中的人体、病原体、疾病与药物是个体化治疗的关键,值得临床高度重视。  相似文献   
38.
ObjectiveObesity has reached epidemic proportions in the US. Physical activity is an important component of obesity reduction, but little is known about contemporary exercise levels among overweight/obese American adults. In this study, we compared current physical activity levels in overweight and obese US adults to those of normal weight individuals as well as ascertained which sociodemographic factors influence the meeting of physical activity recommendations in these three groups.MethodsWe used national data from 2015 and 2017 Behavioral Risk Factor Surveillance System surveys (n = 726,075). Bivariate analyses were conducted to determine unadjusted physical activity levels in normal weight, overweight, and obese adults. We fit multinomial logistic models to identify associations between sociodemographic factors and meeting physical activity recommendations in our study population.ResultsAround 45% of overweight and 57% of obese adults failed to meet physical activity guidelines compared to 41% of normal weight adults. Age, sex, and race were significantly associated with physical activity levels for both overweight and obese adults. In overweight and obese individuals, associations between sociodemographic factors and physical activity were more similar between the two comparisons of insufficiently active (IA) versus active (A)/highly active (HA) and A versus HA but quite different to those in the inactive (IN) versus IA/A/HA comparison.ConclusionsFuture physical activity interventions should be aimed at increasing the number of overweight and obese US adults who meet physical activity guidelines as well as targeted towards specific sociodemographic groups within the overweight/obese population with low exercise levels.  相似文献   
39.
《Heart rhythm》2020,17(5):842-846
  1. Download : Download high-res image (83KB)
  2. Download : Download full-size image
  相似文献   
40.
ObjectiveMethamphetamine is used extensively around the world as a psychostimulant. The complications related to methamphetamine include methamphetamine-induced neurotoxicity, mainly involving intraneuronal processes, such as oxidative stress and excitotoxicity. Curcumin is effective against neuronal injury due to its antioxidant, anti-inflammatory effects. In this study, we examined the protective effects of curcumin against methamphetamine neurotoxicity.MethodsSixty male Wistar rats were divided into the following groups: control (n = 12), DMSO (n = 12), methamphetamine (n = 12), and methamphetamine + curcumin (100 and 200 mg/kg, respectively, intraperitoneal [IP]; n = 12). Neurotoxicity was induced by 40 mg/kg of methamphetamine administrated through 4 injections (4 × 10 mg/kg, q2h, IP). Curcumin (100 and 200 mg/kg) was administered at 7 days after the last methamphetamine injection. By using a Morris water maze task, the hippocampus-dependent memory and spatial learning were evaluated 1 day after the last curcumin injection. Then, the animal brains were isolated for biochemical measurements, as well as glial fibrillary acidic protein (GFAP), ionized calcium-binding adaptor protein-1(Iba-1) and caspase-3 immunohistochemical staining.ResultsThe current study demonstrated that administration of curcumin significantly attenuates spatial memory impairment (P < 0.01) following methamphetamine neurotoxicity. Curcumin caused a significant increase in the levels of superoxide dismutase and glutathione peroxidase (P < 0.05). However, it decreased tumor necrosis factor (TNF-α) (P < 0.05) and malondialdehyde (P < 0.01) levels as compared to the methamphetamine group. Also, curcumin significantly reduced Iba-1 (P < 0. 01), GFAP and caspase-3 positive cells in the hippocampus (P < 0.001).ConclusionCurcumin exerted neuroprotective effects on methamphetamine neurotoxicity because of its antioxidant and anti-inflammatory effect.  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