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   2092篇
  免费   139篇
  国内免费   13篇
耳鼻咽喉   42篇
儿科学   110篇
妇产科学   28篇
基础医学   191篇
口腔科学   308篇
临床医学   199篇
内科学   327篇
皮肤病学   15篇
神经病学   138篇
特种医学   221篇
外科学   195篇
综合类   35篇
一般理论   1篇
预防医学   170篇
眼科学   23篇
药学   166篇
肿瘤学   75篇
  2022年   10篇
  2021年   18篇
  2020年   13篇
  2019年   14篇
  2018年   32篇
  2017年   31篇
  2016年   27篇
  2015年   33篇
  2014年   42篇
  2013年   68篇
  2012年   84篇
  2011年   93篇
  2010年   57篇
  2009年   67篇
  2008年   77篇
  2007年   72篇
  2006年   81篇
  2005年   63篇
  2004年   79篇
  2003年   83篇
  2002年   73篇
  2001年   98篇
  2000年   67篇
  1999年   59篇
  1998年   38篇
  1997年   36篇
  1996年   33篇
  1995年   31篇
  1994年   34篇
  1993年   29篇
  1992年   39篇
  1991年   38篇
  1990年   44篇
  1989年   46篇
  1988年   45篇
  1987年   44篇
  1986年   42篇
  1985年   49篇
  1984年   29篇
  1983年   27篇
  1982年   26篇
  1981年   24篇
  1980年   15篇
  1979年   22篇
  1978年   22篇
  1976年   15篇
  1975年   14篇
  1974年   12篇
  1969年   12篇
  1967年   9篇
排序方式: 共有2244条查询结果,搜索用时 15 毫秒
81.
82.
83.
Several classes of tooth-colored materials are available for restoring carious and noncarious cervical lesions. Included are the composite resins, which can be bonded into the cervical area to provide predictable form, function, and esthetics. Part I of this two-part report reviewed the etiology of noncarious cervical lesions and provided a series of clinical case reports showing the importance of the periodontal aspect of lesion management. In part II we present information about adhesive preparation design and esthetic restoration of the noncarious cervical lesion.
CLINICAL SIGNIFICANCE
When used with proper attention to preparation design and restoration placement and finishing, resin composites can be used to successfully restore form, function, and esthetics to defective cervical areas of teeth.  相似文献   
84.
The universally accepted concept of delay-loaded dental implants has recently been challenged. This study hypothesizes that early loading (decreased implant healing time) leads to increased bone formation and decreased crestal bone loss. We used 17 minipigs to study implants under a controlled load, with non-loaded implants for comparison. Radiographic and histological assessments were made of the osseointegrated bone changes for 3 healing times (between implant insertion and loading), following 5 months of loading. The effect of loading on crestal bone loss depended on the healing time. Early loading preserved the most crestal bone. Delayed loading had significantly more crestal bone loss compared with the non-loaded controls (2.4 mm vs. 0.64 mm; P < 0.05). The histological assessment and biomechanical analyses of the healing bone suggested that loading and bioactivities of osteoblasts exert a synergistic effect on osseointegration that is likely to support the hypothesis that early loading produces more favorable osseointegration.  相似文献   
85.
Ultraviolet B radiation is immunosuppressive by multiple mechanisms. In interleukin-4-/- mice, ultraviolet B radiation was not able to suppress delayed-type hypersensitivity or contact hypersensitivity responses when the sensitizing antigen was applied to nonirradiated sites. In contrast, ultraviolet B significantly suppressed contact hypersensitivity responses to haptens applied to irradiated sites in interleukin-4-/- mice. In mast cell depleted Wf/Wf mice, ultraviolet B radiation also significantly suppressed contact hypersensitivity responses to sensitizing antigens applied to irradiated but not to unirradiated sites. In both interleukin-4-/- mice and Wf/Wf mice, the mast cell product, histamine, was immunosuppressive implicating mast cells as the dysfunctional cell in interleukin-4-/- mice. The prevalence of dermal mast cells was similar in wild-type and interleukin-4-/- mice. Dermal mast cells of interleukin-4-/- mice, however, express very low levels of c-kit and did not significantly degranulate in response to ultraviolet B. Ultraviolet radiation induced significant and similar levels of serum interleukin-10 in wild-type and interleukin-4-/- mice. We conclude that interleukin-4 indirectly affects ultraviolet B suppression of contact hypersensitivity and delayed-type hypersensitivity responses to sensitizing antigens applied at sites other than those irradiated by providing a critical differentiative signal for dermal mast cells. This study further emphasizes the central role of mast cells in the initial processes by which ultraviolet B radiation is immunomodulatory for immune responses to sensitizing antigens applied to nonirradiated sites.  相似文献   
86.
Chronic subdural hematoma in children   总被引:3,自引:0,他引:3  
Chronic subdural hematoma (CSH) is generally a disease affecting the elderly and infants. In infants, the process is particularly confusing and frequently misunderstood. In the pediatric population, CSH is just one of a group of sometimes related conditions known as extracerebral fluid collections. In the past, extracerebral fluid collections, in general, and CSHs, in particular, have been inaccurately or incompletely described. Modern neuroimaging techniques, however, have greatly advanced our understanding of these conditions. Surprisingly little literature exists on the subject, and publications before the advent of modern computed tomography and magnetic resonance imaging should be interpreted with caution.  相似文献   
87.
BACKGROUND: Benign ureteral strictures are a potentially difficult problem that typically has been solved by open surgery. However, minimally invasive methods would be preferable. PATIENTS AND METHODS: Three patients with benign ureteral strictures were treated with endoscopic placement of self-expanding permanent indwelling stents (Wallstents). The etiologies of the obstruction were multifactorial and included retroperitoneal fibrosis, stones, traumatic ureteroscopy, ureteral ischemia, and previous open surgery. RESULTS: One patient died with a functioning stent 1 year, 7 months after placement. The other two patients are doing well 5 years, 2 months and 5 years, 11 months afterward (mean 51 months). CONCLUSION: Insertion of a permanent indwelling self-expanding ureteral stent is relatively easy, and long-term successes are documented. Placement of Wallstents for benign ureteral strictures should be considered as a treatment alternative.  相似文献   
88.
89.
90.
Five of the six families with the Berardinelli Seip syndrome in Norway cluster in six adjacent rural municipalities of south-western Norway. The six patients from this area were born between 1951 and 1973, none between 1974 and 1995. The absence of new cases may be explained by a decrease in the intraregion marriage rate and inbreeding. Genealogical investigations show that the mutation must have occurred at least 400 years ago. The sixth family was clinically different and geographically sporadic from a Finnish-descent rural East Norwegian population. A genetic linkage study of all six families revealed fresh crossovers versus the disease allele in nine DNA marker systems and the absence of recombination in three (maximum lod score + 1.3). None of the last showed allelic association. These families are included in an international effort to map the CLBS locus. The patients have been included in the homozygosity testing of totally 28 patients in an international collaborative study. The three patients, assumed identical in descent from both parents, were jointly homozygous in none of the 250 dinucleotide markers tested. A heterochromatic 9qh + segregated from one parent in two families.  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