首页 | 官方网站   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   3998篇
  免费   284篇
  国内免费   20篇
医药卫生   4302篇
  2021年   58篇
  2020年   30篇
  2019年   40篇
  2018年   71篇
  2017年   53篇
  2016年   46篇
  2015年   63篇
  2014年   83篇
  2013年   123篇
  2012年   172篇
  2011年   193篇
  2010年   99篇
  2009年   79篇
  2008年   150篇
  2007年   167篇
  2006年   170篇
  2005年   176篇
  2004年   142篇
  2003年   156篇
  2002年   130篇
  2001年   122篇
  2000年   119篇
  1999年   101篇
  1998年   74篇
  1997年   79篇
  1996年   81篇
  1995年   57篇
  1994年   52篇
  1993年   51篇
  1992年   96篇
  1991年   85篇
  1990年   76篇
  1989年   104篇
  1988年   85篇
  1987年   91篇
  1986年   87篇
  1985年   80篇
  1984年   67篇
  1983年   50篇
  1982年   38篇
  1981年   25篇
  1980年   34篇
  1979年   52篇
  1978年   43篇
  1977年   31篇
  1976年   49篇
  1975年   36篇
  1974年   24篇
  1973年   32篇
  1972年   26篇
排序方式: 共有4302条查询结果,搜索用时 62 毫秒
1.
2.
3.
Retained biliary stones remain a common clinical problem in patients after surgery. Since 1984, the authors have used choledochoscopy in the treatment of suspected retained biliary stones in 75 patients. These procedures were performed in the radiology department with use of local anesthesia supplemented by an intravenously administered sedative and analgesic. A 15-F flexible fiberoptic choledochoscope was used. Fifty-one of the 75 patients were treated as outpatients. Treatment was successful in 74 of 75 patients; in one patient, intrahepatic stones were not completely removed. Electrohydraulic lithotripsy was used to fragment calculi in 11 patients (15%). Biopsies were performed in four patients (5%). Five minor complications occurred; three required overnight admission. Choledochoscopic-assisted removal of retained biliary calculi is a highly effective and safe procedure. Advantages over standard fluoroscopic stone removal include the ability to directly visualize and fragment adherent or impacted stones and visualize noncalculous filling defects, such as air bubbles, mucus, and biliary tumors.  相似文献   
4.
1. The disposition of AY-30,068 (I), a new tetrahydrocarbazole analgesic drug, was studied in mice, rats, dogs, rhesus monkeys, and man. 2. Oral doses of the 14C-labelled drug in aqueous solution were well absorbed in rodents, but absorption of oral doses of the crystalline drug in dogs was poor. Due to the virtual absence of serum metabolites in rats and dogs, the bioavailability of I was nearly identical to the extent of absorption. Although a small first-pass effect was observed in mice, unchanged I represented a major portion of serum radioactivity. 3. A linear increase in the serum concentrations of I occurred at doses between 0.05 and 25 mg/kg in rats, 0.1 and 50 mg/kg in dogs, and 1-160 mg in man. In rhesus monkeys given a 0.5 mg/kg oral dose, the Cmax and AUC of I were similar to values obtained following a corresponding dose in dogs. 4. After i.v. administration of a 1.0 mg/kg dose the terminal elimination half-life (t1/2 beta) of I was 4 h in mice and 9-10 h in rats and dogs. In rodents, dogs, and several human subjects, the elimination of I was interrupted by secondary peaks. Enterohepatic circulation was confirmed in bile duct cannulated rats, where the t1/2 beta of I was decreased to 2.4 h. In rodents the serum clearance and apparent volume of distribution of I were 0.04-0.2 l/kg.h and 0.5-0.8 l/kg, respectively, and 0.6 l/kg.h and 9.8 l/kg in dogs. 5. In rodents and dogs dosed with 14C-labelled I, radioactivity was excreted almost entirely in the faeces. No unchanged I was detected in rat bile, while about 70% of the radioactivity corresponded to conjugates of parent drug.  相似文献   
5.
6.
Scabies     
Scabies is an ectoparasite caused by the mite Sarcoptes scabiei var hominis , an obligate human parasite. There are about 300 million cases of scabies in the world each year. Common predisposing factors are overcrowding, immigration, poor hygiene, poor nutritional status, homelessness, dementia, and sexual contact. Direct skin-to-skin contact between 15 and 20 minutes is needed to transfer the mites from one person to another. The diagnosis suspected with a clinical history of itch, worse at night, affecting other family members, clinical distribution, and appearance. Definite diagnosis relies on microscopic identification of the mites, eggs, or fecal pellets with 10% potassium hydroxide, ink enhancement, tetracycline fluorescence tests, or mineral oil; other methods include: epiluminescence light microscopy and S. scabiei DNA. The most commonly used treatment modalities are permethrin and ivermectin. Persistence of symptoms for 2–6 weeks after successful treatment is common. Most recurrences are because of reinfection from untreated contacts.  相似文献   
7.
8.
PURPOSE: This study aims to determine the effect of loss of breast cancer metastasis suppressor 1 (BRMS1) protein expression on disease-free survival in breast cancer patients stratified by estrogen receptor (ER), progesterone receptor (PR), or HER2 status, and to determine whether loss of BRMS1 protein expression correlated with genomic copy number changes. EXPERIMENTAL DESIGN: A tissue microarray immunohistochemical analysis was done on tumors of 238 newly diagnosed breast cancer patients who underwent surgery at the Cleveland Clinic between January 1, 1995 and December 31, 1996, and a comparison was made with 5-year clinical follow-up data. Genomic copy number changes were determined by array-based comparative genomic hybridization in 47 breast cancer cases from this population and compared with BRMS1 staining. RESULTS: BRMS1 protein expression was lost in nearly 25% of cases. Patients with tumors that were PR negative (P=0.006) or HER2 positive (P=0.039) and <50 years old at diagnosis (P=0.02) were more likely to be BRMS1 negative. No overall correlation between BRMS1 staining and disease-free survival was observed. A significant correlation, however, was seen between loss of BRMS1 protein expression and reduced disease-free survival when stratified by either loss of ER (P=0.008) or PR (P=0.029) or HER2 overexpression (P=0.026). Overall, there was poor correlation between BRMS1 protein staining and copy number status. CONCLUSIONS: These data suggest a mechanistic relationship between BRMS1 expression, hormone receptor status, and HER2 growth factor. BRMS1 staining could potentially be used in patient stratification in conjunction with other prognostic markers. Further, mechanisms other than genomic deletion account for loss of BRMS1 gene expression in breast tumors.  相似文献   
9.
Ultrasensitive bright field in situ hybridization assays using enzyme metallography (EnzMet) have been developed and validated, but little is known regarding the applicability of EnzMet for immunophenotypic detection of protein via IHC. Superior resolution via discrete metallographic deposits offers the potential for enhancing high-resolution immunophenotyping. Using high-complexity tissue microarrays (TMAs), 88 common solid tumors were evaluated by automated EnzMet (Nanoprobes and Ventana). Targets were chosen to assess the ability of EnzMet to specifically localize encoded antigens in the nucleus (estrogen receptor), cytoplasm (cytokeratins), and cytoplasmic membrane (HER2) in TMAs. Results were compared with conventional IHC diaminobenzidine (DAB) immunostaining. There was full concordance between the EnzMet and conventional IHC results. Furthermore, the EnzMet reaction products did not appreciably diffuse, were dense and sharply defined, and provided excellent high-resolution differentiation of cellular compartments in paraffin sections for the nuclear, cytoplasmic, and cell membrane-localized antigens evaluated. The higher density of elemental silver deposited during enzyme metallography permitted evaluation of core immunophenotypes at a relatively low magnification, allowing more tissue to be screened in an efficient manner. This preliminary study shows the utility of using enzyme metallography for high-resolution immunophenotyping in TMAs.  相似文献   
10.
An experimental model with a static positioning frame, pressure-sensitive film (Fuji), and a microcomputer-based video digitizing system, previously developed by the two senior authors, was used in this study to examine the effects of increasing perilunate instability on the load transfer characteristics of the wrist. These effects included a significant dorsal ulnar shift of the scaphoid centroid with increasing perilunate instability together with a less dramatic palmar ulnar shift of the lunate centroid. Overall, the scaphoid contact area was found to decrease as the stage of perilunate instability increased, even in ulnar deviation and/or extension, which in the normal wrist was found to be the positions that had the greatest scaphoid contact area. Average pressures in the high pressure zones were found to significantly increase in wrists with a stage III instability compared with normal wrists. An increase in the intercentroid (scaphoid/lunate) distance was most evident with the wrist in 20 degrees extension, neutral radioulnar deviation, and 90 degrees supination.  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-23

京公网安备 11010802026262号