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   2846篇
  免费   90篇
  国内免费   15篇
耳鼻咽喉   12篇
儿科学   100篇
妇产科学   65篇
基础医学   292篇
口腔科学   52篇
临床医学   139篇
内科学   951篇
皮肤病学   76篇
神经病学   170篇
特种医学   60篇
外科学   471篇
综合类   38篇
现状与发展   2篇
预防医学   286篇
眼科学   63篇
药学   79篇
中国医学   14篇
肿瘤学   81篇
  2024年   2篇
  2023年   24篇
  2022年   50篇
  2021年   86篇
  2020年   82篇
  2019年   310篇
  2018年   210篇
  2017年   114篇
  2016年   71篇
  2015年   80篇
  2014年   87篇
  2013年   80篇
  2012年   29篇
  2011年   38篇
  2010年   26篇
  2009年   32篇
  2008年   32篇
  2007年   21篇
  2006年   26篇
  2005年   18篇
  2004年   9篇
  2003年   12篇
  2002年   7篇
  2001年   13篇
  2000年   14篇
  1999年   16篇
  1998年   7篇
  1997年   6篇
  1996年   2篇
  1995年   3篇
  1994年   7篇
  1992年   4篇
  1991年   3篇
  1989年   1篇
  1987年   1篇
  1986年   1篇
  1985年   79篇
  1984年   170篇
  1983年   134篇
  1982年   140篇
  1981年   145篇
  1980年   102篇
  1979年   125篇
  1978年   117篇
  1977年   75篇
  1976年   103篇
  1975年   83篇
  1974年   79篇
  1973年   73篇
  1945年   1篇
排序方式: 共有2951条查询结果,搜索用时 0 毫秒
81.
To gain information concerning the natural history and prevalence of pulmonary gas exchange abnormalities resulting from intravenous drug abuse, 45 intravenous drug users were studied. Twenty subjects used a mixture of the synthetic opiate pentazocine and the antihistamine tripelennamine, which, under the street name T's and B's, has become very popular in some urban areas as an available substitute for heroin. Compared with the 19 heroin addicts studied, the pentazocine and tripelennamine users had a significantly shorter mean duration of intravenous drug abuse (2.7 +/- 0.4 years versus 7.6 +/- 0.9 years, p less than 0.01), a greater frequency of respiratory symptoms (75 percent versus 36 percent, p less than 0.05), a significant reduction in the mean diffusing capacity of the lung for carbon monoxide (58.4 +/- 3.3 percent predicted versus 75.5 +/- 5.6 percent predicted, p less than 0.01), and abnormal responses to submaximal steady-state exercise testing. The intravenous use of pentazocine and tripelennamine and probably most other drug preparations intended for nonparenteral use represents a particularly noxious form of drug abuse that may lead to early respiratory complications in a large proportion of users.  相似文献   
82.
Foot‐and‐mouth disease (FMD) is endemic in Kenya where four serotypes (O, A, SAT 1 and SAT 2) of the virus are currently in circulation. Within 2010 and 2011, the National Laboratory recorded an increase in the number of FMD outbreaks caused by serotype O virus. The characteristics of these viruses were determined to ascertain whether these were independent outbreaks or one single strain spreading throughout the country. The sequences of the complete VP1‐coding region were analysed from viruses sampled within different areas of Kenya during 2010 and 2011. The results indicated that the 2010 to 2011 outbreaks in Kenya were caused by four independent strains. By comparison with earlier type O isolates from Eastern Africa, it was apparent that the outbreaks were caused by viruses from three different lineages of topotype EA‐2 and a fourth virus strain belonging to topotype EA‐4. The topotypes EA‐1 and EA‐3 were not detected from these outbreaks. Implications of these results for FMD control in Eastern Africa are discussed.  相似文献   
83.
84.
85.
Burning and stabbing pain in the feet and lower limbs can have a significant impact on the activities of daily living, including walking, climbing stairs and sleeping. Peripheral neuropathy in particular is often misdiagnosed or underdiagnosed because of a lack of awareness amongst both patients and physicians. Furthermore, crude screening tools, such as the 10‐g monofilament, only detect advanced neuropathy and a normal test will lead to false reassurance of those with small fiber mediated painful neuropathy. The underestimation of peripheral neuropathy is highly prevalent in the South‐East Asia region due to a lack of consensus guidance on routine screening and diagnostic pathways. Although neuropathy as a result of diabetes is the most common cause in the region, other causes due to infections (human immunodeficiency virus, hepatitis B or C virus), chronic inflammatory demyelinating polyneuropathy, drug‐induced neuropathy (cancer chemotherapy, antiretrovirals and antituberculous drugs) and vitamin deficiencies (vitamin B1, B6, B12, D) should be actively excluded.  相似文献   
86.
严重急性呼吸综合征冠状病毒(SARS-CoV)、中东呼吸综合征冠状病毒(MERS-CoV)和严重急性呼吸综合征冠状病毒2(SARS-CoV-2)是目前已知的三种人类高致病性冠状病毒,由非结构蛋白、结构蛋白、附属蛋白和核糖核酸组成。病毒粒子通过冠状病毒的刺突糖蛋白(S蛋白)识别宿主受体,以膜融合方式进入宿主细胞,通过大型复制转录复合体在宿主细胞内复制,并通过干扰和抑制宿主的免疫应答来促进增殖。人类高致病性冠状病毒的宿主是人和脊椎动物,病毒粒子通过飞沫、接触、气溶胶等途径感染肺部细胞,也可能通过消化道、尿液、眼部等其他途径传播。本文基于现有研究结果讨论人类高致病性冠状病毒的增殖和传播机制,以期为阻断其传播和致病提供依据。  相似文献   
87.
Background and Objectives Appropriate screening for irregular red‐cell antibodies is essential for ensuring transfusion compatibility and for antenatal management of mothers at risk of haemolytic disease of the foetus and newborn. Screening for all relevant antibodies is, however, limited by screening cells that do not express antigens present in the patient and donor population. Technology to artificially incorporate antigens into red cells is currently available and may be an option for customizing screening cells. Materials and Methods We sought to identify retrospectively the changing patterns of alloantibody prevalence in our multiethnic population on change of screening cells. Antibody screening records of 143 501 patients tested from 2004 to 2010 were retrieved and divided into two groups: period‐1 (2004–2008) and period‐2 (2009–2010). During period‐1, standard screening cells were used while in period‐2, MUT+Mur+ KODE? transformed red cells (kodecytes) were used. Results Four per cent of samples tested during period‐2 were positive on antibody screening compared to 3·2% in period‐1. Specific antibodies, excluding anti‐D, were identified in 1·66% and 1·52% of patients in period‐2 and ‐1, respectively. When confined to antibodies of clinical significance only, period‐2 showed higher alloantibody prevalence of 1·16% as compared to 0·66% in period‐1. Antibodies to glycophorin variants of MNS (vMNS) were more commonly detected while antibodies to Lewis antigens declined during period‐2. Conclusion Antibodies to vMNS antigens are common in South and East Asian populations and are often missed when using standard screening cells. Use of specifically engineered screening cells to express red‐cell antigens artificially is beneficial in detecting the diverse alloantibodies present in our population.  相似文献   
88.
OBJECTIVE: To investigate the association between angiotensinogen gene M235T polymorphism and ischemic stroke in East Asians. DATA RETRIEVAL: A computer-based online search was conducted in PubMed, Google scholar, China National Knowledge lnfrastructure database between January 1990 and April 2012 for relevant studies. The were angiotensinogen or AGT, polymorphism or genetic and ischemic stroke or cerebral infarction. SELECTION CRITERIA: Case-controlled studies addressing the correlation between angiotensinogen gene M235T polymorphism and ischemic stroke in East Asians were included. The distribution of genotypes in the included studies was tested for Hardy-Weinberg equilibrium. Quality evaluation of the included studies was conducted by two physicians. Statistical analyses were carried out using Stata 12.0 software for meta-analysis. Heterogeneity tests, sensitivity analysis and publication bias were also conducted. MAIN OUTCOME MEASURES: The association between angiotensinogen gene M235T polymorphism and ischemic stroke risk in East Asians was assessed. RESULTS: Six relevant studies involving 891 patients with ischemic stroke and 727 controls were included in this meta-analysis. Results showed that there was a significant association between angiotensinogen gene M235T polymorphism and the risk of ischemic stroke in East Asians (T vs. M: odds ratio (OR) = 1.54, 95% confidence interval (CI) = 1.10-2.16; TT vs. MM: OR = 2.24, 95%CI = 1.37-3.66; TT vs. MT: OR = 1.76, 95%CI = 1.41-2.20; MM + MT vs. TT: OR = 0.57, 95%CI = 0.46-0.70). Sensitivity analysis confirmed that the study results were stable and reliable, with no publication bias. CONCLUSION: The angiotensinogen gene M235T polymorphism is associated with ischemic stroke in East Asians, and the TT genotype and T allele are risk factors for ischemic stroke.  相似文献   
89.
This paper describes briefly Aponte's "Family-School Interview" and its application in school-family conflict situations. The goals and suppositions of this systems-theory based model are described and illustrated, and comparisons with more traditional interventions are made. A case study is offered for illustration purposes. Counselors are encouraged to explore its utility for their work in school settings, as well as other, multi-system settings.  相似文献   
90.
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