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   1447篇
  免费   71篇
  国内免费   56篇
耳鼻咽喉   1篇
儿科学   72篇
妇产科学   14篇
基础医学   191篇
口腔科学   26篇
临床医学   191篇
内科学   317篇
皮肤病学   67篇
神经病学   38篇
特种医学   306篇
外科学   96篇
综合类   28篇
预防医学   72篇
眼科学   22篇
药学   74篇
中国医学   2篇
肿瘤学   57篇
  2021年   11篇
  2020年   11篇
  2019年   12篇
  2018年   21篇
  2017年   9篇
  2016年   10篇
  2015年   14篇
  2014年   25篇
  2013年   53篇
  2012年   33篇
  2011年   24篇
  2010年   47篇
  2009年   68篇
  2008年   26篇
  2007年   63篇
  2006年   37篇
  2005年   30篇
  2004年   19篇
  2003年   19篇
  2002年   19篇
  2001年   22篇
  2000年   24篇
  1999年   31篇
  1998年   78篇
  1997年   82篇
  1996年   101篇
  1995年   62篇
  1994年   60篇
  1993年   54篇
  1992年   26篇
  1991年   21篇
  1990年   27篇
  1989年   44篇
  1988年   43篇
  1987年   39篇
  1986年   51篇
  1985年   44篇
  1984年   10篇
  1983年   19篇
  1982年   16篇
  1981年   9篇
  1980年   13篇
  1979年   11篇
  1978年   14篇
  1977年   11篇
  1976年   14篇
  1975年   14篇
  1938年   9篇
  1937年   6篇
  1933年   15篇
排序方式: 共有1574条查询结果,搜索用时 859 毫秒
91.
The objective of the study was to investigate pulse oximetry as a guide to assessing patients with leg ulcers before treatment. Graduated elastic compression is the treatment of choice for uncomplicated venous leg ulcers, but is contra-indicated in patients with significant arterial disease. The standard assessment of arterial insufficiency by Doppler ultrasound ankle branchial pressure index (ABPI) has shortcomings which prompted this investigation of pulse oximetry as a possible additional, or alternative, method of assessment of patients with leg ulcers, prior to treatment with compression. The study, carried out on a population of patients attending hospital leg ulcer clinics, was designed to evaluate pulse oximetry assessment in the selection and monitoring of patients with venous leg ulceration leading to a prospective controlled study of ulcer healing in groups of patients with reduced and normal ABPI, selected for compression therapy by pulse oximetry criteria. Outcome measurement required follow-up of patients selected for compression therapy by pulse oximetry to record time to healing and rate of healing of leg ulcers. Results from the study show a fair correlation between the toe-finger oximetry index (TFOI) and Doppler ABPI. There is no difference between ulcer healing in patients with reduced and normal ABPI selected for treatment on the basis of pulse oximetry maximum compression pressure (MCP). In conclusion, pulse oximetry is an aid to the selection of patients who will benefit from compression therapy, but would be excluded on the basis of Doppler ABPI.  相似文献   
92.
Weaver  DA; Hei  TK; Hukku  B; McRaven  JA; Willey  JC 《Carcinogenesis》1997,18(6):1251-1257
To establish a cell culture model for lung carcinogenesis, independent populations of the human papillomavirus 18-immortalized human bronchial epithelial cell line BEP2D were treated with high linear energy transfer radon-simulated alpha-particles, expanded and xenotransplanted into Nu/Nu mice. Six independent cell lines were established from tumors that developed from three separate radiation treatments as follows: treatment (Tx) 1 (30 cGy--two doses), H2BT, Tx 2 (30 cGy-- single dose), R30T1L, R30T2 and R30T3L, Tx 3 (30 cGy--single dose), H1ATN and H1ATBA1. Cytogenetic analysis revealed common changes in all tumor lines: loss of the Y chromosome (ch), one of three copies of ch8, one of three copies of ch14, and one of two copies of ch4p16-pter and ch11p15-pter. Analysis of polymerase chain reaction-amplified short tandem repeats of informative loci confirmed the loss of chY in all lines and loss of heterozygosity (LOH) at eight loci spanning the length of ch8 in all lines from Tx's 1 and 2. Our data support previous studies indicating the presence of tumor suppressor genes on ch8. LOH also was confirmed on ch14 at locus D14S306 in all cell lines from Tx 2 and in one of two lines from Tx 3. This region, 14q12-q13, may contain changes in one of the five known somatostatin receptor genes (SSTR1). No LOH was detected at any of the informative loci tested for on ch4 or ch11.   相似文献   
93.
Childhood tuberculosis is perceived by many as a disease of the past. Experience in a children's hospital serving a deprived population suggested that tuberculosis and other mycobacterial infections were not declining in clinical practice. Fifty three tuberculous and 11 atypical mycobacterial infections were identified between 1978 and 1992. There was no decline in tuberculosis and nine of the 11 atypical infections occurred in the last five years. Altogether 40% of cases of tuberculosis were in non-Asian children; 32% had arrived in the UK or visited family overseas in the previous year; and 38% had a history of tuberculosis contact, usually a close adult relative. Nationally, the previous decline in tuberculosis in all ages has reversed. In the local health districts in London's east end, childhood tuberculosis has also stopped declining and seems to be increasing. It is regrettable that BCG vaccination has been abolished by some districts in the UK, against current recommendations. Childhood tuberculosis is still common in the practice described here, including among children who do not fall into conventionally recognised high risk groups. Inner city dwellers and junior doctors are both highly mobile populations, adding to the risk that paediatricians, particularly those in training, may encounter tuberculosis with little or no previous experience of the condition.  相似文献   
94.
95.
Multisection, dual-echo magnetic resonance (MR) transaxial images of blood vessels contain both anatomic and qualitative information about flow. Even so, the images are produced as a series of two-dimensional tomographic sections from which full visualization of connected structures is difficult. A computer algorithm was developed that automatically detects flowing blood based on pixel intensity and calculated T2 and provides reconstructed views of vessels while analyzing and displaying flow characteristics. Images of abdominal vessels, aortic aneurysms, and the heart were encoded by flow and color to demonstrate depth. In addition, these data were reconstructed to derive a more accurate assessment of patency. With this technique, transaxial images can be used to analyze flow patterns, determine patent areas, and visualize all levels of vessels in a single image.  相似文献   
96.
To analyze the benefit of a departmental IT group in comparison to support by hospital IT groups or system manufacturers in a completely digitized radiological department. The departmental IT group comprises a fulltime IT specialist, two student assistants and four clinical employees participating 1 day/week. For 18 months IT problems were quantified and specified according to urgency, responsibility and affected system by use of an intranet-based reporting system. For each IT service provider the performance and duration of problem solution was evaluated. In 18 months 3,234 IT problems emerged. 88.7% were solved by the departmental IT group. In 474 cases (14.7%) a solution within 2 h was required. The departmental IT group solved 35.8% within 30 min, system manufacturers needed 18 h 38 min in mean. The departmental IT group solved 90.2% of the problems within a time limit. System manufacturers met the limit in 60.1% with a mean duration of 7 days 21 h. In 6.7% of the cases, support by system manufacturers was indispensable. A considerable proportion of IT problems in completely digitized radiological departments can be solved by a departmental IT group, providing a fast and cost-efficient first-level IT support with effective prevention of major breaks in the workflow. In a small number of cases support by system manufacturers remains necessary.This work was orally presented on ECR 2004 in Vienna.  相似文献   
97.
Carcinoma of the papilla of Vater. A review of fifty-seven cases   总被引:3,自引:0,他引:3  
Fifty-seven cases of carcinoma of the papilla of Vater are reviewed. Clinical and pathologic features as well as results of various surgical treatments are summarized. The Whipple operation may be the operation of choice for cancer of the papilla of Vater, offering a chance for cure and obviating further surgery.  相似文献   
98.
Herbert Brown was Consultant Dermatologist to the Victoria Infirmary, Glasgow during the first half of the 20th Century. He was a keen amateur photographer, and his large archive of photographs illustrates comprehensively the work of a clinical dermatologist in that era.  相似文献   
99.
OBJECTIVE: To determine whether children's food consumption is increased by the size of the group of children in which they are eating. DESIGN: Crossover study. SETTING: University based preschool. PARTICIPANTS: 54 children, aged 2.5-6.5 years. INTERVENTIONS: Each child ate a standardised snack in a group of three children, and in a group of nine children. MAIN OUTCOME MEASURES: Amount each individual child consumed, in grams. RESULTS: Amount eaten and snack duration were correlated (r = 0.71). The association between group size and amount eaten differed in the short (<11.4 min) versus the long (> or =11.4 min) snacks (p = 0.02 for the interaction between group size and snack duration). During short snacks, there was no effect of group size on amount eaten (16.7 (SD 11) g eaten in small groups vs 15.1 (6.6) g eaten in large groups, p = 0.42). During long snacks, large group size increased the amount eaten (34.5 (16) vs 26.5 (13.8), p = 0.02). The group size effect was partially explained by a shorter latency to begin eating, a faster eating rate and reduced social interaction in larger groups. CONCLUSIONS: Children consumed 30% more food when eating in a group of nine children than when eating in a group of three children during longer snacks. Social facilitation of food consumption operates in preschool-aged children. The group size effect merits consideration in creating eating behaviour interventions.  相似文献   
100.
Volumetric rendering of MR images   总被引:1,自引:0,他引:1  
The authors developed new techniques for three-dimensional display of magnetic resonance (MR) images that preserve soft-tissue definition, are fully automatic, and work with routinely used section thicknesses. MR images are segmented, selectively enhanced, and displayed by means of a volumetric rendering algorithm. These techniques were used to illustrate normal anatomy of the brain, knee, and liver. Three-dimensional rendering of balanced spin-echo images shows the ventricles and extracerebral veins and of T1-weighted images, the sulci and gyri. The large hepatic and portal vessels can be seen with these enhancement techniques. Three-dimensional views of the knee reveal articular surfaces of the tibia and clearly depict menisci and posterior and anterior cruciate ligaments. These techniques make it possible to image multiple soft tissues simultaneously while preserving the detail contained in the original images. Three-dimensional presentation of complex, overlapping anatomic regions is helpful in surgical planning and should lead to improved diagnosis.  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