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   8360篇
  免费   685篇
  国内免费   34篇
耳鼻咽喉   112篇
儿科学   319篇
妇产科学   319篇
基础医学   1064篇
口腔科学   255篇
临床医学   845篇
内科学   1511篇
皮肤病学   260篇
神经病学   723篇
特种医学   360篇
外科学   1108篇
综合类   228篇
一般理论   7篇
预防医学   760篇
眼科学   66篇
药学   575篇
中国医学   14篇
肿瘤学   553篇
  2021年   113篇
  2020年   64篇
  2019年   103篇
  2018年   121篇
  2017年   88篇
  2016年   89篇
  2015年   139篇
  2014年   174篇
  2013年   285篇
  2012年   347篇
  2011年   356篇
  2010年   207篇
  2009年   186篇
  2008年   323篇
  2007年   359篇
  2006年   331篇
  2005年   347篇
  2004年   324篇
  2003年   333篇
  2002年   306篇
  2001年   285篇
  2000年   302篇
  1999年   251篇
  1998年   98篇
  1997年   77篇
  1996年   87篇
  1995年   81篇
  1994年   84篇
  1993年   62篇
  1992年   190篇
  1991年   210篇
  1990年   204篇
  1989年   180篇
  1988年   181篇
  1987年   203篇
  1986年   188篇
  1985年   162篇
  1984年   148篇
  1983年   113篇
  1982年   86篇
  1981年   80篇
  1980年   69篇
  1979年   106篇
  1978年   77篇
  1977年   59篇
  1976年   63篇
  1974年   78篇
  1973年   91篇
  1972年   74篇
  1970年   78篇
排序方式: 共有9079条查询结果,搜索用时 0 毫秒
91.
Multiple Renaut bodies were identified by light microscopy in the biopsied common peroneal nerve of a dog with generalized neuropathy, hypothyroidism and a history of cutaneous mastocytosis. In addition, numerous granulated cells were associated with most of the Renaut bodies. Electron microscopic examination confirmed these to be mast cells, both central and peripheral to Renaut bodies, a phenomenon never previously reported. Endoneurial fibrosis, myelinated fiber loss, as well as evidence of axonal degeneration, demyelination and remyelination were observed. 'Vacuolation' of endoneurial fibroblasts was also present. The location of these Renaut bodies in the common peroneal nerve, and the absence of any documented or expected nerve compression, implicates other etiological factors. These observations are the first to report an association between mast cells and Renaut bodies. It is possible that mast cells, at least in this case, are involved in the formation of Renaut bodies.  相似文献   
92.
Sixty-six patients had surgery for an intramedullary nerve sheath tumour under the care of one surgical team in a 16-year period. Surgery concentrated on radical intra- and extradural excision combined if necessary with vertebral column reconstruction. Ninety procedures were used in 35 males and 30 females with an age range 12-81 years. Forty-five per cent were located in the cervical, 26% in the thoracic and 29% in the lumbosacral region. Eighteen patients had NF1 and two patients NF2. Sixty-five per cent were schwannomas, 27% were mixed histology and 6% malignant. In terms of functional outcome, 37 patients improved by one or more Frankel grades, three deteriorated by one Frankel grade and no one who presented with symptoms alone deteriorated. There were no operative deaths; no instrumentation failures and five patients developed a CSF leak.  相似文献   
93.
OBJECTIVES: The object of this study was to evaluate the results of a comprehensive clinical care pathway (CCP) aimed at reducing the length of hospitalization and overall cost for patients undergoing radical prostatectomy in a setting including both academic and private physicians. METHODS: The clinical records of 1,129 consecutive patients who underwent radical prostatectomy by 24 urologists between July 1, 1990, and December 31, 1996, were reviewed. The factors considered were length of stay, morbidity and mortality, readmission rates, and average cost. The CCP was implemented on January 1, 1994. Its scope was to minimize preoperative evaluation, eliminate the preoperative hospital stay, standardize postoperative care and provide intensive patient education. RESULTS: The average length of stay decreased significantly after implementation of the CCP (8.1 vs. 4.9 days, p = 0.0001). In 1990, there was a large difference in length of stay between academic and private physicians (8.3 vs. 12.6 days) (p = 0. 02) but by 1 year after implementation of the CCP there was virtually no difference (4.69 vs. 4.71 days) (p > 0.05). Complication rates were similar before and after implementation of the CCP. Using the average 1993 cost/case as the baseline preCCP figure, the average cost of radical prostatectomy decreased by 16% in 1994 and by 22% in 1995. CONCLUSIONS: It is possible to successfully implement a CCP in a multi-physician system to reduce length of stay and cost of radical prostatectomy without subjecting the patient to a greater risk of complication.  相似文献   
94.
95.
OBJECTIVE: This study directly compared the clinical validity of 11 empirically defined alcoholism typologies to determine whether some typologies are clinically more valid than others. METHOD: A sample of 360 hospitalized alcoholic men were extensively evaluated at entry into the study and again 1 year later. Twenty-three measures of clinical validity were employed; 15 were postdictive and 8 were predictive. Postdictive retrospective measures obtained at entry into the study included family history, age of onset and lifetime course characteristics associated with alcoholism severity, general psychopathology and psychosocial functioning. Predictive outcome measures drawn from information obtained during the 1-year follow-up included: abstinence, alcoholism severity and clinician ratings of outcome. The measures were subjected to various statistical analyses, including factor analysis. RESULTS: We found that all of the alcoholism typologies met at least 7 of the 23 a priori measures of clinical validity. The correlations between these conceptually and methodologically disparate typologies were often striking. Exploratory factor analysis, which explained 35% of the variance, suggested three possible underlying dimensions to account for the overlap among typologies: (1) age and its correlates, including age-of-alcoholism onset; (2) "pure" alcoholism versus psychiatrically heterogeneous alcoholism that encompassed antisocial personality disorder; and (3) current severity of psychiatric distress, impairment and dysfunction. CONCLUSIONS: No single method of subtyping alcoholics clearly emerged as superior. All demonstrated some degree of predictive and postdictive clinical validity. Most methods of subtyping correlated positively with each other at moderate, but typically significant, levels.  相似文献   
96.
Rates of prostate cancer (PCa) have increased so dramatically over the last decade that the age adjusted incidence rate for PCa is now greater than that any other cancer among men in the United States. This review, published as a three part series, provides a state-of-art assessment of the PCa problem in its divergent aspects.Part 1 covers epidemiology, incidence and progression. Several epidemiological studies have demostrated that first degree male relatives of men with PCa are at increased risk of developing the disease. Familial and genetic factors as well as medical, anthropometric, dietary, hormonal and occupational factors involved in PCa are discussed. Postmortem examination of the prostate in men without evidence of PCa documented a high frequency of adenocarcinoma. Latent disease occurred as early as the second decade of life. Although there is no significant difference in incidence between Caucasian and African-American males, high grade prostatic intraepithelial neoplasia (HGPIN) is higher in the latter group. While dietary fat, androgens and certain environmental factors may be determinants for PCa, the exact mechanism of tumorigenesis is still relatively unknown. The current thinking of the role of genomic instability, chromosomal alterations, tumor suppressor genes and the androgen receptor are explored.  相似文献   
97.
After small lesions within the cortex of area 4 of the monkey degenerating axon terminals have been seen with the electron microscopy to contact the cell bodies, proximal parts of the apical dendrites and initial segments of Betz cells 0.5 to 2.5 mm from the damage. The degenerating axon terminals make symmetrical synapses which are presumed to be inhibitory in function. The degenerating terminals are probably from the axons of the basket cells described in Golgi-impregnated material, and which correspond to the large stellate cell recognized in electron microscopic studies.  相似文献   
98.
Normal mammalian fibroblasts cultured in vitro will not divide indefinitely but undergo senescence and give rise to cells that can no longer be induced to divide. It is possible to overcome this finite life span by either cellular mutation or by the exogenous introduction of some viral or cellular oncogenes. This review describes the characteristics of senescence and the different ways in which it can be overcome.  相似文献   
99.
As part of the Femoro-popliteal Bypass Trial patients undergoing femoro-popliteal vein bypass were randomised to aspirin 300 mg and dipyridamole 150 mg twice daily or identical placebo tablets. Blood was taken from a subgroup of 145 patients (mean age 66.3 years) with patent grafts at 6 months. Serum salicylate analysis revealed that of the 65 randomised to receive placebo 18 (28%) had evidence of salicylate in their sample (greater than 50 ng ml-1). Similarly, in those randomised to active treatment and considered to be good compliers 16/61 (26%) had no evidence of salicylate in their serum sample (less than 50 ng ml-1). Analysis of primary graft patency by "intention to treat" failed to detect a difference by life table, the risk being slightly higher in the group assigned to placebo (RR = 1.33, 95% confidence internal C.I. 0.64-2.78, p = 0.438). When comparing patients with no detectable serum concentration (less than 50 ng ml-1) with patients with serum salicylate over 50 ng ml-1 there was a significant difference in graft patency at 66 versus 83% respectively at 3 years (RR = 2.38, 95%C.I. 1.08-5.26, p = 0.024). When corrected for a number of possible risk factors this significant difference was maintained (RR = 2.78, 95%C.I. 1.15-6.67, p = 0.017). Although these findings are based on observational data they provide indirect evidence of an improvement in graft patency with aspirin. This result combined with the finding of a significant reduction in cardiovascular events in the main trial results support the use of aspirin and dipyridamole in patients undergoing femoro-popliteal vein bypass.  相似文献   
100.
The National Athletic Injury/Illness Reporting System is a national surveillance system created from several workshops at which physicians, athletic trainers, and sports administrators shared their ideas for obtaining meaningful data. The primary objective was to provide a feasible and inexpensive mechanism for the continuous collection and analysis of information on sports-related injuries. Additionally, the project offers institutions and agencies a useful system of recordkeeping. NAIRS collects data on a wide range of sports, however, this report clarifies the risk of injury for high school and college football. Presented are data on neurotrauma, meniscus/knee sprains, and ankle sprains. Playing surface, surface hardness, surface friction, and shoe-turf interface were also examined. It was concluded that no helmet type or brand was associated with unusually high levels of risk. Artificial surfaces did not constitute an additional risk of significant concussion. An association between playing surface and the risk of knee and ankle injuries was observed. J Orthop Sports Phys Ther 1979;1(2):103-108.  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