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   227057篇
  免费   19872篇
  国内免费   14729篇
耳鼻咽喉   1949篇
儿科学   2211篇
妇产科学   2987篇
基础医学   27248篇
口腔科学   3754篇
临床医学   31569篇
内科学   33632篇
皮肤病学   2245篇
神经病学   12762篇
特种医学   8327篇
外国民族医学   138篇
外科学   22415篇
综合类   35810篇
现状与发展   55篇
一般理论   19篇
预防医学   13335篇
眼科学   6854篇
药学   23011篇
  252篇
中国医学   12692篇
肿瘤学   20393篇
  2025年   62篇
  2024年   3043篇
  2023年   4783篇
  2022年   9589篇
  2021年   11815篇
  2020年   9307篇
  2019年   8125篇
  2018年   8093篇
  2017年   7197篇
  2016年   6764篇
  2015年   10305篇
  2014年   12592篇
  2013年   10723篇
  2012年   16049篇
  2011年   17949篇
  2010年   10524篇
  2009年   8184篇
  2008年   11113篇
  2007年   11090篇
  2006年   11229篇
  2005年   11327篇
  2004年   6998篇
  2003年   6609篇
  2002年   5499篇
  2001年   4936篇
  2000年   5341篇
  1999年   5684篇
  1998年   3526篇
  1997年   3497篇
  1996年   2813篇
  1995年   2611篇
  1994年   2144篇
  1993年   1376篇
  1992年   1891篇
  1991年   1595篇
  1990年   1291篇
  1989年   1091篇
  1988年   1014篇
  1987年   890篇
  1986年   726篇
  1985年   525篇
  1984年   336篇
  1983年   242篇
  1982年   149篇
  1981年   145篇
  1980年   111篇
  1979年   143篇
  1977年   53篇
  1975年   57篇
  1974年   56篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
目的了解石家庄机场赴泰国旅客对当地高发传染病的认知现状和个人防护能力情况,为制定高风险航线往来旅客的风险分析方案提供依据。方法采取随机抽样方法,对由石家庄机场赴泰国游的旅客在知情同意的情况下进行面对面的问卷调查,所有资料录入Excel后采用SPSS 13.0软件进行统计分析。结果回收的503份有效调查问卷中,本科学历、收入中等偏上、第一次出境旅游的中青年人群为主体,具有目前出境游人群的代表性;有效问卷中,65.8%的人选择通过旅行社了解赴泰国旅行注意事项;大多数旅客集中选择泰国是"登革热"(42.5%)和"疟疾"(25.2%)的流行区域,而选择"痢疾"和"霍乱"的只占14.1%和11.9%;58.1%的旅客出境前未接种过任何疫苗;23.7%旅客不知道应该到哪里进行旅行前的健康咨询,13.1%不清楚归国后如有发热、皮疹等传染病症状该如何就医。结论评价口岸传染病防控能力现状,逐步构建主动型卫生检疫查验系统;完善风险评估机制,有针对性地对重点航班和人群采取多举措宣教以提升防病意识;应多部门联合持续加强出入境人员的传染病宣教、监测和防控工作。  相似文献   
992.
We investigated potential sources of infection for 6 confirmed influenza A (H5N1) patients who resided in urban areas of People's Republic of China. None had known exposure to sick poultry or poultry that died from illness, but all had visited wet poultry markets before illness.  相似文献   
993.
辽宁省家蝇抗药性研究   总被引:4,自引:2,他引:4  
目的:了解辽宁省家蝇对常用杀虫剂的抗药性状况。方法:常规点滴法。结果:在供试的4种杀虫剂中,以溴氰菊酯的抗药性最为突出,4地家蝇对该杀虫剂的抗性系数分别为118.3、59.7、34和12.8;以下依次为顺式氯氰菊酯、二氯苯醚菊酯和敌敌畏,抗性系数分别为38.2、28.7、24.5、14.2和48.7、29.2、21.4、14.8以及26.6、22.5、20.7、16.8。结论:4地家蝇对供试的4种  相似文献   
994.
This open-label, non-randomized, multicenter trial (Registration: NCT 03661736) aimed to assess if an amino acid-based formula (AAF) supplemented with two human milk oligosaccharides (HMO) supports normal growth and is well tolerated in infants with a cow’s milk protein allergy (CMPA). Term infants aged 1–8 months with moderate-to-severe CMPA were enrolled. The study formula was an AAF supplemented with 2′-fucosyllactose (2′-FL) and lacto-N-neotetraose (LNnT). Infants were fed the study formula for 4 months and were offered to remain on the formula until 12 months of age. Tolerance and safety were assessed throughout the trial. Out of 32 infants (mean age 18.6 weeks; 20 (62.5%) male), 29 completed the trial. During the 4-month principal study period, the mean weight-for-age Z score (WAZ) increased from –0.31 at the baseline to +0.28 at the 4-months’ follow-up. Linear and head growth also progressed along the WHO child growth reference, with a similar small upward trend. The formula was well tolerated and had an excellent safety profile. When comparing the microbiome at the baseline to the subsequent visits, there was a significant on-treatment enrichment in HMO-utilizing bifidobacteria, which was associated with a significant increase in fecal short-chain fatty acids. In addition, we observed a significant reduction in the abundance of fecal Proteobacteria, suggesting that the HMO-supplemented study formula partially corrected the gut microbial dysbiosis in infants with CMPA.  相似文献   
995.
Use of prebiotics is a growing topic in healthcare. A lightweight molecule and water-soluble fiber ingredient, longish glucomannan hydrolysates (LGH), has been developed to improve the intestinal mucosal barrier and confer gut health benefits. This study aims to investigate the implications of continuous LGH intervening in intestinal epithelium integrity and protective immunity against chemical dextran sodium sulfate (DSS)-induced colitis. Twelve male BALB/c mice were randomly arranged into four groups. The LGH/DSS group had results in bodyweight variance, epithelial cell density, and aberrancy score as good as the LGH group, and both were equivalent to the control group. LGH consumption effectively protects the distal intestinal epithelium by activating innate T lymphocytes. Meanwhile, T-cell subsets in subepithelial interspersion take a bystander role in these microenvironmental alterations. Under this stress, the cluster of differentiation 3 (CD3)+ T cells infiltrate the epithelium, while CD4+ T cells inversely appear in submucosal large lymphoid aggregates/isolated lymphoid follicles (ILFs) in which significant CD3+, CD4+, and CD8+ T-cell populations agglomerate. Moreover, forkhead box P3 (Foxp3) and interleukin 17 (IL-17) are observed in these ILFs. Agglomerated CD4+ T-cell lineages may have roles with proinflammatory T helper 17 cells and anti-inflammatory regulatory T cells in balancing responses to intraluminal antigens. Collectively, LGH administration may function in immune modulation to protect against DSS-induced inflammation.  相似文献   
996.
In this work, we obtained an effective way to introduce magnetism into topological insulators, and successfully fabricated single crystal C-Bi2Se3. The structural, electrical and magnetic properties of non-magnetic element X (B, C and N) doped at Bi, Se1, Se2 and VDW gap sites of Bi2Se3 were studied by the first principles. It is shown that the impurity bands formed inside the bulk inverted energy gap near the Fermi level with C doping Bi2Se3. Due to spin-polarized ferromagnetic coupling, the time inversion symmetry of Bi2Se3 is destroyed. Remarkably, C is the most effective dopant because of the magnetic moment produced by doping at all positions. The experiment confirmed that the remnant ferromagnetism Mr is related to the C concentration. Theoretical calculations and experiments confirmed that carbon-doped Bi2Se3 is ferromagnetic, which provides a plan for manipulating topological properties and exploring spintronic applications.  相似文献   
997.
998.
Precise evaluation for flexural ultimate capacity of bridges which are subjected to the collision of over-height trucks is essential for making decisions on corresponding maintenance, strengthening or replacement. When the span of a cross-line continuous bridge with a double-box girder was hit by an overly high vehicle, the concrete floor of one girder was severely damaged, and part of the prestressed strands and reinforcements in the girder were broken. After the double-box girder was removed and separated into two single box girders, the ultimate flexural capacity of both box girders was studied by destructive tests, and a comparison was made between the damaged and undamaged girders. Moreover, finite element analysis was conducted to simulate the failure process. The results show that the flexural bearing capacity of the damaged box girder decreased by 33%, but it was still 1.07 times greater than the design bearing capacity, which basically meets the design requirements. Also, the damaged box girder showed a desirable serviceable limit state for three-axle vehicles and five-axle vehicles, but showed an undesirable serviceable limit state for six-axle vehicles. This study shows that repairing or strengthening the damaged span may be better than demolishing and rebuilding the whole superstructure bridge.  相似文献   
999.
The diet-induced obesity (DIO) mouse model has been widely used for obesity studies. The effects of storage conditions on the composition of nutrients in high-fat diets (HFDs) and their impact on metabolic homeostasis have not been systemically investigated. In the current study, we tested the effects of HFDs stored under different conditions and found that mice fed a HFD stored in the fridge (HFDfri) gained less weight than those fed HFDs stored in the freezer (HFDfre). Further analysis revealed that changes in the relative abundance of medium-chain triglyceride (MCT) in the HFDfri, which have much lower intestinal absorption rates, contributed to the body weight differences. In contrast, exacerbated liver damage and elevated levels of unfolded protein response (UPR) was observed in the mice fed by HFDfri. Depletion of the UPR-regulated gene Nnmt alleviated liver damage via the inhibition of the integrated stress response (ISR). Our study, for the first time, provides evidence that HFD storage conditions can have a significant impact on both body weight changes and liver damage in the DIO model.  相似文献   
1000.
本文运用描述流行病学方法初步探讨了上海市不同空气污染条件下8个社区的中风死亡率(1978~1987)的时空分布及其与室内外空气污染的关系.结果表明中风死亡率与大气污染水平无明显关系,但发现在相同大气污染条件下,燃煤社区的中风死亡率明显高于燃气社区,提示燃煤型室内空气污染可能是中风的重要诱发因素之一.  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