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   1378篇
  免费   67篇
  国内免费   21篇
耳鼻咽喉   8篇
儿科学   52篇
妇产科学   17篇
基础医学   145篇
口腔科学   29篇
临床医学   273篇
内科学   389篇
皮肤病学   7篇
神经病学   43篇
特种医学   210篇
外科学   71篇
综合类   29篇
预防医学   62篇
眼科学   2篇
药学   74篇
肿瘤学   55篇
  2023年   8篇
  2022年   9篇
  2021年   13篇
  2020年   7篇
  2019年   12篇
  2018年   21篇
  2017年   15篇
  2016年   24篇
  2015年   20篇
  2014年   31篇
  2013年   47篇
  2012年   44篇
  2011年   50篇
  2010年   44篇
  2009年   67篇
  2008年   52篇
  2007年   67篇
  2006年   39篇
  2005年   46篇
  2004年   29篇
  2003年   44篇
  2002年   42篇
  2001年   41篇
  2000年   38篇
  1999年   39篇
  1998年   50篇
  1997年   46篇
  1996年   41篇
  1995年   45篇
  1994年   23篇
  1993年   27篇
  1992年   20篇
  1991年   19篇
  1990年   23篇
  1989年   33篇
  1988年   33篇
  1987年   24篇
  1986年   17篇
  1985年   22篇
  1984年   20篇
  1983年   18篇
  1982年   26篇
  1981年   18篇
  1980年   22篇
  1979年   11篇
  1978年   12篇
  1977年   24篇
  1976年   15篇
  1975年   10篇
  1970年   3篇
排序方式: 共有1466条查询结果,搜索用时 265 毫秒
1.
Dose-response curves of angiotensin I (AI, 1.0-1000.0 pmol) and angiotensin II (AII, 1.25-1250.00 pmol) were obtained in isolated rat hearts subjected to control conditions, mild hypoxia (PO2 = 145 mm Hg), reoxygenation, ischemic (perfusion pressure = 35 mm Hg) and reperfusion. Both AI and AII caused dose-dependent coronary flow (CF) of 26 +/- 3 and 27 +/- 2%, respectively. The effects of both AI and AII were substantially attenuated during hypoxia, but were fully restored upon reoxygenation. During ischemia, the effect of AII was unaltered while the effect of AI was enhanced compared to the control (P less than 0.05). This enhancement was reversible on reperfusion. Cardiac conversion of AI, calculated from ED50 values for AI and AII, was significantly increased during ischemia (P less than 0.05). Infusion of saralasin (0.5-5.0 micrograms/min) did not increase CF in any of the groups. We conclude that (1) the coronary vasoconstrictive effect of AII is preserved in ischemia but attenuated in hypoxia and (2) cardiac conversion of AI to AII is enhanced in hearts injured by ischemia.  相似文献   
2.
3.
Coronary artery bypass grafts: visualization with MR imaging   总被引:1,自引:0,他引:1  
Gomes  AS; Lois  JF; Drinkwater  DC  Jr; Corday  SR 《Radiology》1987,162(1):175
  相似文献   
4.
Hysterosalpingography was performed in 31 patients by means of a low-dose scanning-beam digital radiographic system. The technique permits adequate evaluation of gynecologic abnormalities while allowing significant reduction in radiation: 2.4-mR (6.1 X 10(-7) C/kg) exposure to the skin and 0.7-mrad (7 X 10(-6) Gy) mean dose to the ovaries per image obtained. Sixteen patients demonstrated readily recognizable and documented abnormalities, corroborated by laparoscopy, laparotomy, or other supportive evidence.  相似文献   
5.
BACKGROUND: Merkel cell carcinoma is a rare malignant neuroendocrine neoplasm characteristically arising from the dermis of sunlight-exposed skin. It rarely arises outside the skin. OBJECTIVE: We present a patient with primary Merkel cell carcinoma arising from subcutaneous fat, with no involvement of the overlying skin. We describe the clinical manifestations and magnetic resonance imaging (MRI) findings. METHODS: We report a 63-year-old woman with a primary lesion of Merkel cell carcinoma that arose from the subcutaneous fat layer of the left arm. The lesion presented as a subcutaneous nodule with intact overlying skin. MRI showed that the nodular lesion was located entirely in the subcutaneous fat layer, with no involvement of the dermis. Peritumoral infiltration around the lesion and enlarged lymph nodes deep to the lesion were noted. The patient received wide excision of the lesion with dissection of the regional lymph nodes and adjuvant radiotherapy and chemotherapy. RESULTS: Histopathologic examination confirmed the diagnosis of Merkel cell carcinoma with local lymphatic metastasis, and the lesion was completely located in the subcutaneous fat, with no involvement of the dermis. These findings were well correlated with MRI findings. CONCLUSION: Primary Merkel cell carcinoma may arise from the subcutaneous fat and present as an entirely subcutaneous lesion with intact skin. MRI is helpful to evaluate the local extension of the lesion and regional lymphatic metastasis.  相似文献   
6.
表小檗碱对α受体的作用   总被引:2,自引:0,他引:2  
王嘉陵  方达超 《药学学报》1990,25(4):289-292
表小檗碱(epiberberine,EB)是从湖北产黄连(Coptis chinensis Franch)中提取的一种生物碱,属苯喹嗪类原小檗碱,对其药理作用的研究资料甚少,未见其对α肾上腺素体作用的报道。资料表明,许多原小檗碱类化合物有α受体阻滞作用,为从该类化合物中选择  相似文献   
7.
The purpose of this pilot study was to observe both relaxed and deep breathing patterns in a convenience sample to determine the incidence of normal versus faulty patterns of respiration. These observations were then combined with respondent answers to a survey on pain history to determine if there is any correlation between faulty breathing and musculo-skeletal pain patterns. If such a correlation can be made, then we propose that clinicians working with chronic pain patients may have improved outcomes if they address and correct faulty breathing patterns. Based on this study, it is suggested to include the evaluation and treatment of faulty respiration in the rehabilitation of chronic musculo-skeletal conditions, most notably cervical pain.  相似文献   
8.
MR-spectroscopy of the heart is a relatively new technique for the study of various aspects of cardiac metabolism. The majority of results has so far been obtained with the isolated perfused heart. Here, 31P-MR spectroscopy can be employed to measure high-energy phosphate metabolism and intracellular pH repeatedly and non-invasively. Using a technique called saturation transfer, velocities of enzymatic reactions, such as the creatine kinase reaction, can be measured. Intra- and extracellular Na+ and K+ concentrations can be registered with 23Na- and 39K-MR in conjunction with shift reagent. 13C-MR can be used to tackle carbohydrate metabolism. In-situ-R-spectroscopy allows determination of high-energy phosphates in intact large mammals. Clinical applications of MR-spectroscopy remain to be defined; preliminary results indicate high diagnostic and prognostic potential for patients with coronary artery disease and congestive heart failure.  相似文献   
9.
36例踝关节骨折合并下胫腓联合分离的治疗体会   总被引:1,自引:1,他引:0  
李得春 《医学争鸣》2005,26(17):1631-1631
0 引言 踝关节骨折是临床上较常见的关节内骨折,包含了腓骨骨折,内踝骨折,后踝骨折和下胫腓联合的损伤. 处理不当可导致踝穴的变形,下胫腓联合分离后期出现创伤性关节炎.  相似文献   
10.
The immune response to the nominal phosphoprotein (NS protein) of rabies virus was investigated with the use of a vaccinia recombinant virus that expressed the NS protein of a fixed rabies virus strain. Mice of the H-2k haplotype that were injected with either live rabies virus or the vaccinia recombinant virus developed a strong cytolytic T-cell response specific for the NS protein. This response was under immune response (Ir) gene control. The NS protein as presented by the vaccinia recombinant virus was a poor inducer of rabies virus-specific T-helper (Th) cells and B cells in the H-2k background. Furthermore, mice of the H-2k haplotype could not be protected by vaccination with the vaccinia recombinant virus expressing the NS protein, although protection in outbred mice was partial and incomplete. These data indicate that cytolytic T cells to the NS protein of rabies virus are insufficient to protect mice against a challenge with rabies virus.  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