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   7958篇
  免费   680篇
  国内免费   17篇
耳鼻咽喉   59篇
儿科学   365篇
妇产科学   226篇
基础医学   918篇
口腔科学   151篇
临床医学   937篇
内科学   1368篇
皮肤病学   55篇
神经病学   706篇
特种医学   453篇
外科学   1270篇
综合类   170篇
一般理论   2篇
预防医学   738篇
眼科学   180篇
药学   545篇
中国医学   4篇
肿瘤学   508篇
  2021年   99篇
  2020年   67篇
  2019年   97篇
  2018年   124篇
  2017年   93篇
  2016年   97篇
  2015年   113篇
  2014年   145篇
  2013年   255篇
  2012年   302篇
  2011年   339篇
  2010年   185篇
  2009年   158篇
  2008年   306篇
  2007年   336篇
  2006年   338篇
  2005年   295篇
  2004年   293篇
  2003年   265篇
  2002年   264篇
  2001年   284篇
  2000年   287篇
  1999年   266篇
  1998年   167篇
  1997年   138篇
  1996年   135篇
  1995年   126篇
  1994年   118篇
  1993年   91篇
  1992年   201篇
  1991年   187篇
  1990年   189篇
  1989年   163篇
  1988年   187篇
  1987年   138篇
  1986年   171篇
  1985年   159篇
  1984年   143篇
  1983年   122篇
  1982年   81篇
  1981年   69篇
  1980年   56篇
  1979年   109篇
  1978年   75篇
  1977年   72篇
  1976年   60篇
  1975年   74篇
  1974年   74篇
  1973年   77篇
  1972年   62篇
排序方式: 共有8655条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
5.
Background: The management and follow-up of asthma patients presenting at Accident and Emergency (A&E) departments have mostly been studied in children's hospitals or specialised teaching hospitals. Aims: To study the adequacy of assessment, treatment and follow-up of patients presenting at A&E departments in non-teaching hospitals. Methods: A twenty-five per cent sample of presentations to A&E departments in all public hospitals in the Illawarra for one year was selected for a case note audit. Information on demographics, assessment, management and referral was extracted from the A&E case notes and medical records of cases with documentation of a final diagnosis of asthma. Chi square and Fischer's Exact tests were used for comparisons among hospitals. Results: Of 359 presentations with a final diagnosis of asthma, 88% were self referred and only 5% were first presentations. Objective measures of airways obstruction was not documented in 34% of admissions and 48% of nonadmissions. There was no documented follow-up in 28% of cases. The assessment and management of asthma in A&E was significantly poorer in smaller hospitals. Conclusion: Evidence of high use of A&E as a primary care facility by asthma patients was found in the study. There is a need to implement protocols to optimise assessment and treatment of asthma in smaller hospitals. (Aust NZ J Med 1993; 23: 672–677.).  相似文献   
6.
Ruggieri  PM; Laub  GA; Masaryk  TJ; Modic  MT 《Radiology》1989,171(3):785-791
The technique and feasibility of magnetic resonance (MR) angiography of intracranial vessels were studied in 35 healthy volunteers. Variations in image orientation, repetition time (TR), and flip angle were evaluated to determine their effects on flow-related enhancement. Gradient modifications--including echo time (TE), motion compensation, bandwidth, and field of view--were also studied in an effort to reduce motion-induced phase shifts. Results indicated that a FISP (fast imaging with steady precession) sequence with a TR of 50 msec, TE of 15 msec, velocity compensation in the read and section-select directions, acceleration compensation in the read direction, anisotropic volume, and a 1.25-mm partition thickness produced three-dimensional angiographic MR images that were accurate and reproducible in the depiction of the major intracranial vessels. Difficulties with field of view, persistent signal void secondary to higher-order motion, and spatial resolution remain major problems requiring additional study.  相似文献   
7.
Scurvy is a nondiscriminatory disease process resulting from a nutritional deficiency of ascorbic acid (vitamin C). The severe vitamin deficiency produces a breakdown in the cellular structure of the body. This case report describes a middle-age woman with a history of edema, bruising of the lower extremities, anemia, and severe periodontal disease. Her presentation and medical history are classic for the signs of scurvy. Scurvy is now only uncommonly seen in developed countries, but there are still vulnerable populations whose nutritional status can lead to scurvy. The aim of this report is to help the clinician identify and treat scurvy, a disease that was once feared for its high mortality but is now easily treatable, even in cases that have progressed to multiple organ dysfunction and failure.  相似文献   
8.
D. W. Barnes, D. A. Sirbasku & G. H. Sato, (eds.): Cell culture methods for molecular and cell biology. P. M. Gootman (ed.): Developmental neurobiology of the autonomic nervous system. M. Sandler, C. Feuerstein, B. Scatton (eds.): Neurotransmitter interactions in the basal ganglia. Harry M. Zimmerman (ed). Progress in neuropathology. M. Yahr & K. J. Bergmann (eds.): Parkinson's disease. G. Bock & M. O'Connor (eds.): Selective neuronal death. H. Julia Hannay (ed.): Experimental techniques in human neuropsychology. D. Papakostopoulos, S. Butler, I. Martin (eds.): Clinical and experimental neuropsychophysiology J. C. Rothwell: Control of human voluntary movement.  相似文献   
9.
Alanine, glutamate and proline labeled with 14C and 3H were infused into fasted normal and adrenalectomized rats. Alanine was administered by the A-V mode (arterial administration-venous sampling), and glutamate and proline by both the A-V and V-A (venous administration-arterial sampling) modes. The kinetics of 14C alanine and 14C glutamate differed markedly from those of the tritium-labeled compounds, but there was little difference in the kinetics of 3H and 14C proline. The replacement rate calculated from the A-V mode for glutamate was about half that obtained in the V-A mode, but there was little difference with proline. The masses of the amino acids (total content of amino acids in the body) were calculated from the washout curves of the tritium-labeled compounds after the infusion of tracer was terminated. The masses for the normal rats were 407 mumol/kg for alanine, 578 mumol/kg for glutamate and 296 mumol/kg for proline. The so-called distribution spaces calculated conventionally from total masses and the amino acid concentrations in plasma are much greater than the volume of the body, reflecting the fact that amino acid concentrations in tissues greatly exceed those in plasma. Adrenalectomy markedly affected the kinetics of the three amino acids, and their replacement rates were greatly reduced. The proline and glutamate masses were reduced by at least one half, while that of alanine was unchanged. Adrenalectomy markedly reduced the conversion of proline to glutamate. The hydrocortisone regimen used in this study restored the metabolism of alanine and glutamate to normal, but had no effect on that of proline.  相似文献   
10.
Biliary stent causing colovaginal fistula: case report.   总被引:2,自引:0,他引:2  
OBJECTIVES: Perforation of the bowel during placement of a biliary stent is a known complication of this procedure. We report the endoluminal loss of a biliary stent during routine stent extraction that ultimately led to a chronic colovaginal fistula. This case emphasizes the need for evaluation of fecal passage of stents in patients with a known dislodged prosthesis. CASE REPORT: A 65-year-old white female underwent biliary stent placement for an episode of choledocholithiasis. The stent was lost in the duodenum during routine extraction. The patient was managed expectantly. She denied ever passing this stent via the rectum and began to develop symptoms of colovaginal fistula. Evaluation found a retained biliary stent in the sigmoid colon and a fistula into the vagina. The patient underwent elective low anterior resection and colovaginal fistula repair. DISCUSSION: Reports exist of migration of stents that lead to acute colonic perforation and the need for emergent surgery. For this reason, it has been suggested that dropped or migrated stents be purposefully retrieved. However, if the option of expectant observation is used, it is important to clearly document the fecal passage of these stents and be prepared to retrieve these objects if they have a prolonged bowel transit time.  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