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   20652篇
  免费   1200篇
  国内免费   192篇
耳鼻咽喉   135篇
儿科学   1199篇
妇产科学   300篇
基础医学   2507篇
口腔科学   358篇
临床医学   1250篇
内科学   3562篇
皮肤病学   407篇
神经病学   1313篇
特种医学   849篇
外国民族医学   5篇
外科学   2804篇
综合类   822篇
一般理论   1篇
预防医学   1408篇
眼科学   1061篇
药学   2064篇
  5篇
中国医学   313篇
肿瘤学   1681篇
  2022年   184篇
  2021年   412篇
  2020年   274篇
  2019年   309篇
  2018年   371篇
  2017年   295篇
  2016年   385篇
  2015年   456篇
  2014年   605篇
  2013年   792篇
  2012年   1124篇
  2011年   1149篇
  2010年   694篇
  2009年   565篇
  2008年   951篇
  2007年   952篇
  2006年   890篇
  2005年   856篇
  2004年   761篇
  2003年   764篇
  2002年   713篇
  2001年   625篇
  2000年   640篇
  1999年   577篇
  1998年   264篇
  1997年   262篇
  1996年   228篇
  1995年   210篇
  1994年   166篇
  1993年   172篇
  1992年   364篇
  1991年   394篇
  1990年   356篇
  1989年   410篇
  1988年   309篇
  1987年   315篇
  1986年   256篇
  1985年   275篇
  1984年   239篇
  1983年   213篇
  1982年   137篇
  1981年   122篇
  1980年   113篇
  1979年   188篇
  1978年   126篇
  1975年   134篇
  1974年   143篇
  1973年   136篇
  1972年   124篇
  1971年   142篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.

Objective

Hypertonic saline (HTS) has potent immune and vascular effects. We assessed recipient pretreatment with HTS on allograft function in a porcine model of heart transplantation and hypothesized that HTS infusion would limit endothelial and left ventricular (LV) dysfunction following transplantation.

Methods

Heart transplants were performed after 6 hours of cold ischemic storage. Recipient pigs were randomized to treatment with or without HTS (7.5% NaCl) before cardiopulmonary bypass (CPB). Using a myograft apparatus, coronary artery endothelial-dependent (Edep) and -independent (Eind) relaxation was assessed. LV performance was determined using pressure-volume loop analysis. Pulmonary interleukin (IL)-2, IL-6, and tumor necrosis factor (TNF)-α expression was measured.

Results

Weaning from CPB and LV performance after transplantation were improved in HTS-treated animals. Successful weaning from CPB was greater in the HTS-treated hearts (8 of 8 vs 2 of 8; P < .05). Mean LV functional recovery was improved in the HTS-treated animals, as assessed by preload recruitable stroke work (65 ± 10% vs 27 ± 10%; P < .001) and end-systolic elastance (55 ± 7% vs 37 ± 4%; P < .001). Treatment with HTS resulted in improved Edep (mean maximum elastance [Emax], 56 ± 5% vs 37 ± 7%; P < .001) and Eind (mean Emax%, 77 ± 6% vs 52 ± 4%; P < .001) vasorelaxation compared with control. Pulmonary expression of IL-2, IL-6, and TNF-α increased following transplantation, whereas HTS therapy attenuated IL production (P < .001). Transplantation increased plasma TNF-α levels and LV TNF-α expression, whereas HTS prevented this up-regulation (P < .001).

Conclusions

Recipient HTS pretreatment preserves allograft vasomotor and LV function, and HTS therapy limits CPB-induced injury. HTS may be a novel recipient intervention to prevent graft dysfunction.  相似文献   
4.
目的:观察中西医结合治疗排卵障碍性不孕症的疗效。方法:82例按随机数字表法分为对照组和观察组各41例。两组均给予常规西药治疗,观察组加用腹针温阳法治疗。结果:受孕成功率观察组84.44%,对照组71.11%,两组比较差异有统计学意义(P<0.05)。观察组优质卵泡直径小于对照组(P<0.05),优质卵泡数量以及子宫内膜厚度均高于对照组(P<0.05)。两组卵巢动脉血流PI、RI、PSV与EDV指标均优于治疗前(P<0.05),且观察组各项指标均优于对照组(P<0.05)。结论:中西医结合治疗排卵障碍性不孕症可改善卵泡发育以及卵巢动脉血流指标,提高受孕率。  相似文献   
5.
6.
Endoscopic clips have been used mainly for control of gastrointestinal (GI) bleeding and occasionally for closure of GI perforations. However, closure of spontaneous esophageal perforation (Boerhaave's syndrome) by clipping has not been reported. We described successful non-surgical closure of spontaneous esophageal perforation by endoscopic clipping in a patient with bilateral pyopneumothorax and septicemia.  相似文献   
7.
Both ultrashort echo-time STEAM and MEGA-PRESS-edited spectroscopy were used to validate noninvasive quantification of vitamin C (ascorbate) in the developing rat brain, where changes in ascorbate concentration have been reported. Despite strong overlap with resonances from glutamine, glutamate, glutathione, and macromolecules, reliable quantification of ascorbate (Cramer-Rao lower bounds<0.2 micromol/g) by LCModel analysis of STEAM (TE=2 ms) spectra was possible at 9.4 T. Ascorbate concentrations quantified from the STEAM spectra were in very good agreement with concentrations calculated from fully resolved ascorbate resonances in MEGA-PRESS-edited spectra measured from identical volumes of interest. Ascorbate concentrations measured using STEAM decreased with increasing postnatal rat age, in agreement with published brain ascorbate concentrations measured in vitro using high-performance liquid chromatography (HPLC).  相似文献   
8.
BACKGROUND: Abnormalities in calcium and vitamin D metabolism have been reported after bariatric surgery. The purpose of this study was to evaluate vitamin D nutritional status among morbidly obese patients before gastric bypass surgery. METHODS: We prospectively studied 279 morbidly obese patients seeking gastric bypass surgery for vitamin D nutritional status as assessed by serum 25-hydroxyvitamin D level. In addition, serum samples were analyzed for calcium, alkaline phosphatase (AP), intact parathyroid hormone (PTH), and 1,25-dihydroxyvitamin D. RESULTS: Mean patient age was 43 +/- 9 years; 87% of the study patients were women, and 72% were white. Serum calcium and AP levels were normal in 88% and 89% of the patients, respectively. Vitamin D depletion, defined as serum 25-hydroxyvitamin D level 相似文献   
9.
10.
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