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   993篇
  免费   32篇
  国内免费   1篇
耳鼻咽喉   2篇
儿科学   35篇
妇产科学   14篇
基础医学   52篇
口腔科学   33篇
临床医学   146篇
内科学   295篇
皮肤病学   52篇
神经病学   19篇
特种医学   2篇
外科学   124篇
综合类   17篇
一般理论   6篇
预防医学   82篇
眼科学   13篇
药学   120篇
  1篇
肿瘤学   13篇
  2016年   9篇
  2015年   13篇
  2014年   15篇
  2013年   31篇
  2012年   9篇
  2010年   26篇
  2009年   34篇
  2007年   10篇
  2006年   10篇
  2001年   11篇
  1999年   20篇
  1998年   43篇
  1997年   49篇
  1996年   37篇
  1995年   31篇
  1994年   41篇
  1993年   34篇
  1992年   31篇
  1991年   13篇
  1990年   28篇
  1989年   22篇
  1988年   32篇
  1987年   20篇
  1986年   24篇
  1985年   21篇
  1984年   12篇
  1983年   14篇
  1982年   15篇
  1981年   19篇
  1980年   13篇
  1979年   18篇
  1978年   11篇
  1977年   9篇
  1976年   8篇
  1975年   11篇
  1971年   9篇
  1970年   8篇
  1966年   10篇
  1963年   13篇
  1962年   9篇
  1961年   9篇
  1960年   12篇
  1959年   13篇
  1958年   32篇
  1957年   19篇
  1956年   16篇
  1955年   12篇
  1954年   15篇
  1949年   9篇
  1948年   14篇
排序方式: 共有1026条查询结果,搜索用时 0 毫秒
1.
2.
3.
Involvement of the urinary bladder in an inguinal hernia is common, but massive bladder hernia is rare. Most urinary bladder herniations are discovered and repaired during surgery. We report a case of large incarcerated inguino-scrotal hernia, which was reduced only to present as a scrotal abscess and vesicocutaneous fistula; an unusual complication. The patient was managed conservatively due to underlying comorbidities.  相似文献   
4.
Latent inhibition (LI) is a reduction in the rate of acquisition of a Pavlovian conditioned response that results from prior nonreinforced preexposure to a conditioned stimulus (CS). LI has been suggested to reflect the operation of mechanisms involved in stimulus selection for subsequent cognitive processing. The present experiment was conducted to assess the effect of bilateral lesions of the nucleus basalis magnocellularis (NBM) on LI employing a conditioned emotional response paradigm. Bilateral lesions of the NBM were produced by administration of 0.12 M quisqualic acid and resulted in decreased cortical acetylcholinesterase staining, as well as a 40% reduction in cortical choline acetyltransferase activity. Following lever press training, preexposed animals received 40 presentations of a 60-s tone CS. Nonpreexposed animals received no tone presentations. Acquisition of conditioned suppression was then assessed over the course of 4 tone-shock (0.6 mA, 0.5 s) pairings. Control, preexposed animals displayed a retarded rate of acquisition in comparison to nonpreexposed controls, thereby demonstrating that the parameters used in the present experiment produced LI. In contrast, lesioned animals preexposed to the CS acquired conditioned suppression as readily as non-preexposed lesioned animals. However, the acquisition of conditioned suppression in both lesioned groups was found to be similar to that displayed in the preexposed control group. This pattern of results was interpreted as being attributable to a lesion-induced impairment in the ability to maintain stimulus processing, rather than a deficit in the ability to filter a stimulus. Copyright © 1996 Elsevier Science Inc.  相似文献   
5.
Despite improvements in supportive care, the mortality and morbidity of asthma remain constant. The risks and incidence of morbidity related to barotrauma remain high in patients that require mechanical ventilation. The authors present three alternative strategies including the inhalation of anaesthetic agents, helium/oxygen ventilation, and extracorporeal membrane oxygenation which may be beneficial when 'conventional therapies' fail in the intubated patient with status asthmaticus.  相似文献   
6.
BACKGROUND: In the United States melanoma is the only individually reported skin cancer. There are no large state or national registries for nonmelanoma skin cancer. Nevertheless, rare, that is, nonmelanoma, nonepithelial, tumors can also be locally aggressive and metastasize. OBJECTIVES: This study's purpose was to demonstrate that Mohs surgeons can share data to create a rare skin tumor database. This database may serve as a model for a nationwide database. MATERIALS AND METHODS: We retrospectively reviewed the surgery logs of five Mohs surgery practices in the Houston, Texas, area for rare-nonmelanoma, nonepithelial-skin cancers. A total of 42,279 biopsy-proven cancers of the skin treated with Mohs micrographic surgery were reviewed. Tumor data including type, prevalence, year of treatment, and the treating Mohs surgeon(s) were compiled and analyzed. RESULTS: Forty-three types of rare tumors were identified. A total of 317 rare tumors were treated. No practice saw more than 28 rare tumor types. Atypical fibroxanthoma was the rare tumor most often treated. CONCLUSIONS: Colleagues can cooperate to create a database of rare tumors removed by Mohs micrographic surgery. A range of tumors greater than that seen in any single practice is now available for study. This should provide the impetus for a nationwide rare skin tumor database.  相似文献   
7.
8.
Localized tissue ischemia is a key factor in the development and poor prognosis of chronic wounds. Currently, there are no standardized animal models that provide sufficient tissue to evaluate the effect of modalities that may induce angiogenesis, and in vitro models of angiogenesis do not mimic the complexity of the ischemic wound bed. Therefore, we set out to develop a reproducible ischemic model for use in wound-healing studies. Male Sprague-Dawley rats underwent creation of dorsal bipedicle skin flaps with centrally located excisional wounds. Oxygen tension, wound-breaking strength, wound area, lactate, and wound vascular endothelial growth factor (VEGF) were compared in flaps measuring 2.5 and 2.0 x 11 cm with and without an underlying silicone sheet. We found that the center of the 2.0 cm flap with silicone remains in the critically ischemic range up to 14 days without tissue necrosis (33+/-4 vs. 49+/-6 mmHg in controls). Wound healing and breaking strength were significantly impaired and tissue lactate from the center of this flap was 2.9 times greater than tissue from either nonischemic controls and 2.5 cm flap (0.23+/-0.05 mg/dL/mg sample vs. 0.09+/-0.02 and 0.08+/-0.02, respectively). Vascular endothelial growth factor was 2 times greater than the nonischemic control. This ischemic wound model is relatively inexpensive, easy to perform, reproducible, and reliable. The excisional wounds provide sufficient tissue for biochemical and histologic analysis, and are amenable to the evaluation of topical and systemic therapies that may induce angiogenesis or improve wound healing.  相似文献   
9.
10.
Sendai virus (SV), mouse hepatitis virus (MHV), and pneumoniavirus of mice (PVM) are common viral infections of mice. Influenceof these viral infections on the prevalence of liver tumors,lung tumors, and lymphoma is of concern in chemical carcinogenicitystudies. Body weight, survival, and tumor prevalence of B6C3F1mice with and without viral infections in 33 male and 34 femaleuntreated control groups and 32 male and 32 female low- andhigh-dose groups of 2-year chemical carcinogenicity studieswere evaluated. In male mice, the SV infection was associatedwith significantly (p < 0.05) higher survival of control,low-dose, and high-dose groups, and higher prevalence of livertumors and lymphoma. The increases in tumor prevalence are possiblydue to an increase in the survival of male mice that had SVinfection. However, when interlaboratory variability and time-relatedeffects were taken into account, the number of significant effectswas consistent with the expected false-positive rate inherentto the statistical procedures. The MHV and PVM infections didnot cause consistent changes in body weight, survival, and tumorprevalences in the control and chemical treatment groups ofmale mice. Viral infections did not cause consistent increasesor decreases in body weight, survival, or tumor prevalence inthe control and chemical treatment groups of female B6C3F1 mice.  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