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   11152篇
  免费   532篇
  国内免费   46篇
耳鼻咽喉   98篇
儿科学   736篇
妇产科学   283篇
基础医学   1190篇
口腔科学   212篇
临床医学   657篇
内科学   2146篇
皮肤病学   343篇
神经病学   534篇
特种医学   375篇
外国民族医学   1篇
外科学   1619篇
综合类   530篇
一般理论   11篇
预防医学   446篇
眼科学   511篇
药学   1133篇
中国医学   52篇
肿瘤学   853篇
  2023年   70篇
  2022年   168篇
  2021年   320篇
  2020年   170篇
  2019年   238篇
  2018年   274篇
  2017年   222篇
  2016年   273篇
  2015年   294篇
  2014年   373篇
  2013年   526篇
  2012年   733篇
  2011年   779篇
  2010年   461篇
  2009年   350篇
  2008年   585篇
  2007年   564篇
  2006年   505篇
  2005年   461篇
  2004年   455篇
  2003年   356篇
  2002年   345篇
  2001年   306篇
  2000年   310篇
  1999年   270篇
  1998年   132篇
  1997年   114篇
  1996年   133篇
  1995年   95篇
  1994年   75篇
  1993年   52篇
  1992年   125篇
  1991年   164篇
  1990年   133篇
  1989年   113篇
  1988年   122篇
  1987年   84篇
  1986年   95篇
  1985年   96篇
  1984年   76篇
  1983年   72篇
  1979年   66篇
  1978年   47篇
  1977年   39篇
  1975年   36篇
  1973年   38篇
  1972年   41篇
  1971年   44篇
  1969年   32篇
  1968年   44篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
BackgroundCystic Fibrosis (CF) is a multi-systemic disorder resulting from genetic variation in the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) gene which can result in bronchiectasis, chronic sinusitis, pancreatic malabsorption, cholestatic liver disease and distal intestinal obstructive syndrome. This study generates multi-dimensional clinical phenotypes that capture the complexity and spectrum of the disease manifestations seen in adult CF patients using statistically robust techniques.MethodsPre-transplant clinical data from adult (age ≥18 years) CF patients (n = 992) seen in six regionally distinct US CF centers between 1/1/2014 and 6/30/2015 were included. Demographic, spirometry, nutritional, microbiological and therapy data were used to generate clusters using the Random Forests statistical-learning and Partitioning around Medoids (PAM) clustering algorithms. Five commonly measured demographic, physiological and nutritional parameters were needed to create the final phenotypes that are highly similar to a regionally matched group of patients from the CF Foundation Patient RegistryResultsThis approach identified high-risk phenotypes with expected characteristics including high rates of pancreatic insufficiency, diabetes and Pseudomonas aeruginosa colonization. It also identified unexpected populations including a) a male-dominated, well-nourished group with good lung function with a high prevalence of severe genotypes (i.e. 60% subjects had two minimal function CFTR variations), b) and an older, “survivor” phenotype that had high rates of chronic P. aeruginosa infection.ConclusionsThis study identified recognizable phenotypes that capture the clinical complexity in a statistically robust manner and which may aide in the identification of specific genetic and environmental factors responsible for these disease manifestation patterns.  相似文献   
62.
63.
64.
To find out the efficacy of sucralfate in preventing gastrointestinal side effects of non-steroidal anti-inflammatory drugs (NSAIDs) a prospective, randomised single blind study was conducted from 1989 to 1992. Patients with osteoarthritis, rheumatoid arthritis and other long standing painful conditions, who were expected to receive NSAIDs for over three months, were recruited into the study. All medicines were discontinued for a period of 10–15 days prior to initial endoscopic assessment. NSAID therapy was started and the patients were randomised to receive either placebo (group A) or sucralfate (group B) in addition. Patient were reassessed clinically every week and an endoscopic examination was repeated after 6–8 weeks of follow-up. A total of 176 patients were studied in group A (n=91) and group B (n=85). At the end of 8 weeks gastrointestinal symptoms were present in 30.6% and 26.4% patients of group A and B respectively. Endoscopic assessment showed superficial lesions in 36.5% and 18.7% while endoscopic ulcer in 2.4% and 1.1% patients of groups A and B respectively. Thus in patients receiving chronic NSAID therapy, simultaneous administration of sucralfate reduces the incidence of superficial gastric lesions but has no significant effect on symptoms or ulcer formation.KEY WORDS: Gastropathy, Sucralfate, Nonsteroidal anti-inflammatory drugs  相似文献   
65.
The clinical profile of typhoid fever in an infant is variable and non-specific. A rare case of typhoid fever in a 7 month old infant is reported. The child presented with only a day's history of fever and loose motions which resulted in severe dehydration, acute tubular necrosis and death. The diagnosis of typhoid fever was made only on post-mortem study. The problem in diagnosing typhoid fever in a young infant is highlighted with a brief literature review on the subject.  相似文献   
66.
Rapid slide culture method using human blood medium was utilized for the primary culture of Mycobacterium tuberculosis and the results obtained were compared with results of smear examination of sputum specimens from fresh cases of pulmonary tuberculosis. Smear and rapid slide culture results of a total of 320 patients were analyzed. Slide culture was positive in 104 cases whereas smears were positive in 90 cases. Early culture confirmation in 7 days coupled with positivity better than smear examination, makes rapid slide culture a better method for diagnosis.KEY WORDS: Mycobacterium tuberculosis, Rapid slide culture, Bacteriological techniques, Colony count microbial  相似文献   
67.
Transplantation has come of age as an important investigative tool for studying normal growth and development of the brain tissue. The present study reports the effect of lateral hypothalamic (LHA) lesion and foetal hypothalamic tissue transplantation on the feeding behaviour. In a group of rats, LHA was lesioned bilaterally by passing direct current. Subsequently, in a separate group of rats, foetal hypothalamic tissue was transplanted at the lesioned site. Following LHA lesion, all the rats died of aphagia and adipsia within 7 days, whereas, the rats in whom foetal hypothalamus was transplanted, started taking food and water in small quantities from the first day of transplantation itself. Later, they were able to attain their preoperative values. This recovery of the feeding behaviour following foetal tissue transplantation may be due to the formation of synaptic connections or due to the release of neurotrophic factors.  相似文献   
68.
69.
There is evidence from clinical, epidemiological, and neuroimaging studies that attention-deficit hyperactivity disorder (ADHD) and seasonal affective disorder (SAD) may have several features in common. To assess seasonal affective symptoms in adults with ADHD, 115 individuals attending an adult ADHD clinic in Toronto, Ontario, Canada were asked to complete the Seasonal Pattern Assessment Questionnaire (SPAQ). From this clinic population of 115, a total of 56 completed SPAQs were returned. Assuming that all individuals failing to complete the SPAQ were nonseasonal and depending on which case-finding criteria were used, the rate of SAD in the overall clinic sample was estimated at either 10.4% (Terman criteria) or 19.1% (criteria of Kasper et al.). These prevalence rates are significantly greater than the rates reported in large population surveys at similar latitudes. There was an apparent relationship between female gender, impulsive-subtype ADHD, and seasonality. Future studies to examine whether core symptoms of ADHD fluctuate across the seasons and to assess the efficacy of light therapy in "seasonal" ADHD patients would be of great theoretical and clinical interest.  相似文献   
70.
PURPOSE: In vitro study of the enzymes involved in aerobic, anaerobic and hexose monophosphate shunt in ultraviolet radiation exposed mice lenses. METHOD: Of the selected enzymes, lactic dehydrogenase (LDH) was representative of anaerobic glucose oxidation, succinic dehydrogenase (SDH) of the aerobic oxidation, and Glucose-6-phosphate dehydrogenase (G-6-PDH) of the Hexose Monophosphate (HMP) shunt. Other enzymes studied were ATPase and glutathione reductase (GR). RESULTS: Experiments with mice lenses in vitro showed that transparent lens became opaque following UV-irradiation at 360 nm. Opacification of the lens was accompanied by a change in enzyme activities for energy metabolism. CONCLUSION: These changes were progressive in a manner analogous to sequential morphological changes, which would be crucial in maintaining lens transparency.  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