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   46369篇
  免费   4020篇
  国内免费   300篇
耳鼻咽喉   697篇
儿科学   1329篇
妇产科学   815篇
基础医学   6858篇
口腔科学   646篇
临床医学   4937篇
内科学   9769篇
皮肤病学   1227篇
神经病学   4445篇
特种医学   1971篇
外国民族医学   1篇
外科学   6914篇
综合类   344篇
现状与发展   1篇
一般理论   31篇
预防医学   3196篇
眼科学   867篇
药学   2994篇
中国医学   230篇
肿瘤学   3417篇
  2023年   166篇
  2022年   432篇
  2021年   1023篇
  2020年   710篇
  2019年   1212篇
  2018年   1418篇
  2017年   1117篇
  2016年   1304篇
  2015年   1721篇
  2014年   2074篇
  2013年   2642篇
  2012年   3324篇
  2011年   3405篇
  2010年   2171篇
  2009年   1894篇
  2008年   2761篇
  2007年   2802篇
  2006年   2706篇
  2005年   2636篇
  2004年   2419篇
  2003年   2394篇
  2002年   2428篇
  2001年   569篇
  2000年   456篇
  1999年   484篇
  1998年   480篇
  1997年   436篇
  1996年   347篇
  1995年   379篇
  1994年   310篇
  1993年   296篇
  1992年   274篇
  1991年   295篇
  1990年   249篇
  1989年   207篇
  1988年   221篇
  1987年   254篇
  1986年   210篇
  1985年   199篇
  1984年   190篇
  1983年   155篇
  1982年   202篇
  1981年   192篇
  1980年   168篇
  1979年   118篇
  1978年   138篇
  1977年   99篇
  1976年   85篇
  1975年   75篇
  1972年   72篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
Accurate assessment and replacement of blood loss and fluid–electrolyte deficit during craniosynostosis repair is difficult owing to patient size and the diversity of surgical technique. Forty-three patients undergoing primary craniosynostosis repair over a 10-year period were studied retrospectively to determine blood loss and fluid deficit and to assess blood transfusion practices during both intraoperative and postoperative periods. Blood loss was calculated on the basis of estimated red cell mass (ERCM) and fluid-electrolyte imbalance was investigated with blood samplings. Blood transfusion was considered appropriate if the postoperative or posttransfusion ERCM was within 12% of the preoperative value. Estimated fluid requirement (EFR) was used in 4 ml kg–1 h–1 except for neonates. Intraoperatively, 80% of all patients were appropriately managed with respect to blood transfusion and EFR. Postoperatively only 20% of the patients receiving transfusions were transfused appropriately. In 23.3% of these patients (10/43) unexpected respiratory distress developed immediately after their recovery from the anesthesia. With the measurement of estimated blood volume and allowable blood loss, appropriate transfusion could be achieved for the successful treatment of the primary craniosynostosis. Received: 16 February 1998  相似文献   
72.
BACKGROUND AND PURPOSE: Marine luminous bacteria were isolated and identified from samples in shallow coastal waters of Taiwan during the relatively warm seasons. METHODS: Identification of the luminous isolates was performed based on differences of phenotypic and genotypic characteristics together with data from phylogenetic analysis. RESULTS: Twenty seven strains of marine luminous bacteria were isolated. They were divided into five types based on differences of phenotypic characteristics. However, they could be clustered into only two genotypes according to the analysis of restriction patterns of polymerase chain reaction-amplified 16S rRNA genes digested with various restriction enzymes. The characterization data together with the 16S rRNA gene-based phylogenetic analysis revealed that the isolates included in phenotype I (seven isolates) could be Photobacterium leiognathi, and those included in phenotypes II-V (twenty isolates) might be classified as Vibrio harveyi. However, phylogeny based on gyrB sequences indicated that phenotypes II-V could be classified into two species, V. harveyi and Vibrio campbellii. CONCLUSION: Culturable luminous bacteria in the shallow coastal waters of Taiwan during the sampling period are dominated by V. harveyi/campbellii and P. leiognathi, and the former species appeared to be more prevalent and numerous than the latter species in general.  相似文献   
73.
74.
75.
76.
Our study was conducted to determine whether use of gastric acid-suppressive agents increased the risk of Clostridium difficile-associated disease (CDAD) in a medical intensive care unit of one of the first hospitals to be threatened by the current CDAD epidemic in Quebec, Canada. Our findings suggest that efforts to determine risk factors for CDAD should focus on other areas, such as older age and antibiotic use.  相似文献   
77.
78.
(11)C-meta-Hydroxyephedrine (HED) is used in cardiac PET as an index of norepinephrine (NE) reuptake transporter (NET) density and synaptic NE levels. Whereas cardiac uptake is well documented, tracer retention in other tissues with rich noradrenergic innervation is unclear. Dysfunctional sympathetic nervous system (SNS) function in extracardiac metabolic storage tissues (i.e., adipose tissue and skeletal muscle) and endocrine organs contributes to several disorders. The aim of this study was to determine the potential of HED as an index of NE function in brown adipose tissue, lung, pancreas, skeletal muscle, and kidney by identifying NET-specific retention and determining the presence of radiolabeled metabolites. METHODS: Male Sprague-Dawley rats were administered HED and sacrificed at 30 min after tracer injection. Tissues were rapidly excised and counted for radioactivity, and relative tracer retention was quantified. Pretreatment with NET inhibitors established specific HED accumulation. The effect of elevated NE was tested by subcutaneous minipump NE infusion or inhibition of monoamine oxidase. Column-switch high-performance liquid chromatography (HPLC) was used to analyze the presence of radiolabeled metabolites in heart, brown adipose tissue, pancreas, and plasma. RESULTS: NET-specific retention was observed in heart, brown adipose tissue, lung, and pancreas but not in liver, skeletal muscle, or kidney. A dose-dependent response of HED accumulation to treatments elevating NE levels was established in tissues exhibiting specific uptake. At 30 min after tracer administration, HPLC analysis revealed 93%-95% of total radioactivity signal derived from unchanged HED in heart, pancreas, and brown adipose tissue compared with 61% +/- 8% unchanged HED in plasma. CONCLUSION: In addition to the heart, lung, pancreas, and brown adipose tissue exhibit specific and NE-responsive uptake of HED, supporting the potential for novel PET studies of SNS integrity in these tissues.  相似文献   
79.
80.
BACKGROUND: The effective dose for treating glabellar lines with botulinum toxin type A in men has not been studied adequately. OBJECTIVE: To compare the safety, efficacy, and duration of response of four doses of botulinum toxin type A on glabellar rhytids in men. METHODS: Eighty men were randomized to receive a total dose of either 20, 40, 60, or 80 U of botulinum toxin type A (BOTOX, BOTOX Cosmetic, or Vistabel, Allergan, Inc., Irvine, CA, USA) in the glabellar area. Glabellar lines were assessed at rest and maximum frown by a trained observer at baseline, 2 and 4 weeks, and monthly thereafter. Patients provided self-evaluations at the same visits. Adverse events were monitored throughout. RESULTS: The 40, 60, and 80 U doses of botulinum toxin type A were consistently more effective in reducing glabellar lines than the 20 U dose (duration, peak response rate, improvement from baseline). There was a dose-dependent increase in both the response rate at maximum frown and the duration of effect assessed by the trained observer. In addition, the participants reported a dose-dependent reduction in the ability to frown, improvement in their global assessment, and increased feelings of attractiveness, self-confidence, and satisfaction. The incidence of adverse events was not increased with higher doses. CONCLUSION: Male participants with glabellar rhytids benefit from starting doses of at least 40 U of botulinum toxin type A.  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