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   6701篇
  免费   357篇
  国内免费   20篇
耳鼻咽喉   70篇
儿科学   116篇
妇产科学   263篇
基础医学   866篇
口腔科学   475篇
临床医学   385篇
内科学   1696篇
皮肤病学   95篇
神经病学   591篇
特种医学   196篇
外科学   993篇
综合类   22篇
一般理论   1篇
预防医学   308篇
眼科学   131篇
药学   319篇
中国医学   18篇
肿瘤学   533篇
  2023年   35篇
  2022年   69篇
  2021年   187篇
  2020年   102篇
  2019年   164篇
  2018年   170篇
  2017年   137篇
  2016年   161篇
  2015年   164篇
  2014年   247篇
  2013年   320篇
  2012年   558篇
  2011年   550篇
  2010年   307篇
  2009年   265篇
  2008年   454篇
  2007年   429篇
  2006年   385篇
  2005年   382篇
  2004年   366篇
  2003年   310篇
  2002年   301篇
  2001年   72篇
  2000年   54篇
  1999年   61篇
  1998年   57篇
  1997年   54篇
  1996年   51篇
  1995年   46篇
  1994年   45篇
  1993年   33篇
  1992年   39篇
  1991年   38篇
  1990年   31篇
  1989年   41篇
  1988年   36篇
  1987年   40篇
  1986年   41篇
  1985年   24篇
  1984年   22篇
  1983年   16篇
  1982年   25篇
  1981年   17篇
  1980年   16篇
  1979年   20篇
  1978年   13篇
  1977年   15篇
  1974年   12篇
  1972年   11篇
  1968年   13篇
排序方式: 共有7078条查询结果,搜索用时 19 毫秒
91.
A tymovirus was isolated in Brazil from tomato plants with severe symptoms of leaf mosaic and blistering. The virus was mechanically transmissible to solanaceous indicator host species. The infected plants contained icosahedral particles and chloroplasts with membrane deformations which are typical cytopathic effects caused by tymoviruses. Its coat protein amino acid sequence shares the maximum of 64 % identity with the tymovirus Chiltepin yellow mosaic virus, which suggested that it can be considered as a distinct member of the genus Tymovirus. In a phylogenetic tree, this tymovirus was clustered with other solanaceous-infecting tymoviruses. It was tentatively named as Tomato blistering mosaic virus (ToBMV).  相似文献   
92.
93.
Respiratory complications are common in the patient with muscular dystrophy. The periodic clinical and instrumental respiratory evaluation is extremely important. Despite the presence in the literature of updated guidelines, patient associations often report lack of knowledge of these pathologies, particularly in peripheral hospitals. The purpose of this work, inspired by the Italian Muscular Dystrophy Association (UILDM) is to improve management of respiratory problems necessary for the management of these patients complex. To this end, the main items that the specialist can meet in the follow-up of these pathologies have been analyzed and discussed, among which the respiratory basal evaluation, the criteria of adaptation to non-invasive ventilation, management of bronchial secretions, situations of respiratory emergency, indications for tracheostomy and the subject of advance directives of treatment (DAT).Key words: respiratory failure, muscular dystrophy, cough efficacy, spirometry, polygraphy, non-invasive ventilation, arterial blood gases, cough machine, invasive ventilation, tracheostomy, mechanical ventilation  相似文献   
94.
Soil sorption, described as logKOC (the logarithm of the soil/water partition coefficient normalized to organic carbon), was modeled using the augmented multivariate image analysis applied to quantitative structure–property relationship method for a series of 11 carboxylic acid herbicides. The statistical model was found to be highly predictive and reliable to estimate logKOC of other persistent organic pollutants in the soil, which are analogues of the carboxylic acids used in the QSPR model. The QSPR model derived from images corresponding to the chemical structures of the 11 herbicides is superior to the uniparameter model based on the octanol/water partition coefficient (logP) and, in addition, a pattern recognition model was built using principal component analysis. This model allowed clustering and separating compounds with low/moderate soil sorption from those with moderate/high soil sorption (compounds with the aryloxy function) using the second principal component.  相似文献   
95.
96.
International Journal of Clinical Pharmacy - The COVID-19 pandemic presents several challenges to the organisation and workflow of pharmacovigilance centres as a result of the massive increase in...  相似文献   
97.
Aneurysms in the pediatric population are a rare pathology with specific features which requires a deep knowledge of their pathogenesis for the best therapeutic choice; the authors report their experience with a patient presenting aneurysm of the middle cerebral artery (MCA) associated with proximal stenosis of the vessel. A six-year-old girl came to our observation after sudden onset of headache and left hemiparesis. Angio-MRI and angio-CT scan showed a right MCA dissecting aneurysms associated with proximal stenosis of the vessel. Patient started a therapy with low molecular weight heparin (LMWH), replaced, 15 days later, with acetyl-salicylic acid (ASA). Patient showed a rapid and almost complete neurological recovery, despite several radiological exams confirmed a complete occlusion of the right MCA. As many other authors noted, dissecting aneurysms in the pediatric population are probably due to a defect of the entire arterial wall. Combination of stenosis, turbulence and partial thrombosis of the aneurysm led to a complete occlusion of artery involved, leading to the formation of collateral circles. In our case, complete thrombosis was probably delayed with anticoagulant therapy and the progressive reinforcement of collateral circles lead to the patient’s neurological recovery.  相似文献   
98.

The insecticides imidacloprid (IMI), a neonicotinoid, and propoxur (PRO), an N-methylcarbamate compound, are pesticides widely used throughout the world. Although they are not used together to combat pests, both are often found in freshwater near agricultural areas. Thereby, the goal of this study was to evaluate the additive effects of IMI and PRO mixtures at environmental concentrations in relation to isolated compounds on Rhamdia quelen, a neotropical fish. The fish was exposed to IMI (0.11 µg/L), PRO (0.039 µg/L), or Mix (0.11 µg/L IMI plus 0.039 µg/L PRO) during 96 h. Glutathione S-transferase (GST), superoxide dismutase (SOD), catalase (CAT), acetylcholinesterase (AChE) activities were determined. To verify oxidative damage thiobarbituric acid reactive substances (TBARS), protein carbonyl (PC), reactive oxygen species contents (ROS), antioxidant capacity against peroxides (ACAP) were determined in gills, liver, brain and muscle. The results shows that a mixture of these pesticides at environmental concentrations inhibited acetylcholinesterase activity in the brain and induced oxidative damage in all analyzed tissues. These results reinforce the hypothesis that mixture of contaminants present in environment could induce additive or synergistic effects on fish species.

  相似文献   
99.
ObjectiveTo identify the urban phlebotomine sandfly fauna in Ponta Porã, Mato Grosso do Sul State, Brazil.MethodsThe captures were undertaken from April 2009 to March 2010 with CDC light traps in 14 ecotopes (intra and peridomicile) in different areas of the city, Shannon traps being used in areas with abundant vegetation.ResultsA total of 707 specimens were captured with CDC light traps (565 males and 142 females) and 155 specimens (112 males and 43 females) with Shannon traps, a total of 862 phlebotomines. The specimens captured belonged to eight species: Lutzomyia longipalpis (Lutz & Neiva, 1912), Evandromyia cortelezzii (Brethes, 1923), Sciopemyia sordelli (Shannon & Del Ponte, 1927), Pintomyia pessoai (Coutinho & Barretto, 1940); Pintomyia monticola (Costa Lima, 1932); Brumptomyia brumpti (Larousse, 1920); Nyssomyia whitmani (Antunes & Coutinho, 1939) and Psathyromyia shannoni (Dyar, 1929). Lutzomyia longipalpis, the main vector of Leishmania (Leishmania) chagasi, was the species most frequently captured (97.03%) and also the most abundant according to the standardized abundance index (SAI)=0.86.ConclusionsThe highest species richness was captured, with CDC light traps, inside the domiciles and the species diversity and evenness in the peridomicile, clearly indicating a preference for anthropic environments.  相似文献   
100.
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