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   20855篇
  免费   453篇
  国内免费   492篇
耳鼻咽喉   598篇
儿科学   1250篇
妇产科学   389篇
基础医学   2104篇
口腔科学   713篇
临床医学   1091篇
内科学   4934篇
皮肤病学   371篇
神经病学   1530篇
特种医学   560篇
外科学   3595篇
综合类   199篇
一般理论   10篇
预防医学   2058篇
眼科学   492篇
药学   1219篇
中国医学   209篇
肿瘤学   478篇
  2024年   4篇
  2023年   19篇
  2022年   52篇
  2021年   79篇
  2020年   79篇
  2019年   102篇
  2018年   124篇
  2017年   54篇
  2016年   122篇
  2015年   68篇
  2014年   107篇
  2013年   49篇
  2012年   1970篇
  2011年   2238篇
  2010年   501篇
  2009年   251篇
  2008年   1732篇
  2007年   1981篇
  2006年   1742篇
  2005年   1881篇
  2004年   1789篇
  2003年   1712篇
  2002年   1605篇
  2001年   1074篇
  2000年   1574篇
  1999年   725篇
  1998年   80篇
  1997年   14篇
  1996年   13篇
  1995年   15篇
  1994年   6篇
  1993年   5篇
  1992年   3篇
  1991年   4篇
  1990年   2篇
  1989年   2篇
  1988年   6篇
  1987年   1篇
  1986年   1篇
  1984年   1篇
  1983年   2篇
  1982年   1篇
  1981年   1篇
  1978年   1篇
  1976年   1篇
  1967年   1篇
  1966年   1篇
  1959年   1篇
  1957年   2篇
  1942年   2篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
951.
952.
Background: Gastrectomy remains the only curative treatment for gastric cancer. However,surgical morbidity and mortality remains high. Our aim was to identify the risk factors thatdetermine operative morbidity and mortality and to describe a simple method for preoperativestratification of morbidity outcome.Methods: Retrospective review of patients who underwent gastrectomy for gastric cancer.Multivariate analysis was used to define risk factors for surgical morbidity and mortality.Results: A total of 208 cases were included. Fifty-one episodes of operative morbidity and 19surgery-related deaths were found. Operative blood loss (risk ratio [RR], 1.0012), serum albumin(RR, 0.42), extent of gastrectomy (RR, 2.8), lymphocyte count (RR, 0.999), and splenectomy (RR,1.51) were the most important risk factors for morbidity. However, location of the tumor, serumalbumin level, and lymphocyte count were the most important preoperative risk factors thatdetermine the appearance of surgical complications. Receiver operating characteristic analysis ofthis model allowed definition of three risk groups in terms of surgical morbidity (11.8%, 28.5%, and52.4%, respectively).Conclusions: A new method for preoperative calculation of the probability of surgical complicationswas developed. It must be validated prospectively and in different settings to be used inpreoperative interventions designed to reduce that risk.  相似文献   
953.
STUDY DESIGN: A multicenter, randomized, double-blind, placebo-controlled, flexible-dose, two-way crossover study conducted June 1996 through January 1997. OBJECTIVES: To evaluate the effect of sildenafil citrate (VIAGRA(R)) on the quality of life (QoL) of men with erectile dysfunction (ED) caused by spinal cord injury (SCI). SETTING: Study centers in Australia, Belgium, France, Germany, Norway, Sweden and the United Kingdom. METHODS: Questions 13 and 14 of the 15-item International Index of Erectile Function (IIEF) addressed QoL issues directly related to ED in 178 men with SCI. A 5-item questionnaire addressing concerns that men had about their erection problems was also used to evaluate the impact of ED on QoL. Several commonly used psychometric instruments, including the Medical Outcomes Survey (MOS) Short Form-12, Psychological General Well-Being Index, and MOS Family Survey, assessed general QoL issues. RESULTS: Significant improvements were seen for overall satisfaction with sex life (IIEF Q13), sexual relationship with partner (IIEF Q14), and concerns about erectile problems (P<0.0001). Improvements were reported in scores for the generic QoL parameters of mental health, well-being, depression, and anxiety (P<0.05 sildenafil versus placebo). CONCLUSION: Treatment with sildenafil can significantly improve key QoL parameters in men with ED caused by SCI. Sponsorship: This study was funded by Pfizer Inc. Spinal Cord (2000) 38, 363 - 370.  相似文献   
954.
Background: It has been reported previously that norepinephrine, when applied to the spinal cord dorsal horn, excites a subpopulation of dorsal horn neurons, presumably inhibitory interneurons. In the current study, the authors tested whether norepinephrine could activate inhibitory interneurons, specifically those that are "GABAergic."

Methods: A transverse slice was obtained from a segment of the lumbar spinal cord isolated from adult male Sprague-Dawley rats. Whole-cell patch-clamp recordings were made from substantia gelatinosa neurons using the blind patch-clamp technique. The effects of norepinephrine on spontaneous GABAergic inhibitory postsynaptic currents were studied.

Results: In the majority of substantia gelatinosa neurons tested, norepinephrine (10-60 [mu]M) significantly increased both the frequency and the amplitude of GABAergic inhibitory postsynaptic currents. These increases were blocked by tetrodotoxin (1 [mu]M). The effects of norepinephrine were mimicked by the [alpha]1-receptor agonist phenylephrine (10-80 [mu]M) and inhibited by the [alpha]1-receptor antagonist WB-4101 (0.5 [mu]M). Primary-afferent-evoked polysynaptic excitatory postsynaptic potentials or excitatory postsynaptic currents in wide-dynamic-range neurons of the deep dorsal horn were also attenuated by phenylephrine (40 [mu]M).  相似文献   

955.
Acute ethanol administration partially inhibits DNA and protein syntheses during liver regeneration (LR) induced by partial hepatectomy (PH) in rats. Previous findings that the magnitude of ethanol's deleterious effects on LR are related to the route and timing of its administration led us to perform studies at the ultrastructural level, comparing ethanol effects on PH-induced LR, as a consequence of its administration route. PH promoted alterations on the endoplasmic reticulum and mitochondria, accompanied by decreased glycogen and increased lipid content in cytoplasm. Structural nuclear and nucleolar activities were also evident. Intragastric ethanol administration practically abolished the adaptative changes found in PH-promoted regenerating hepatocytes, whereas its administration through the intraperitoneal route induced later ultrastructural modifications, indicating cellular proliferation. These results suggest that ethanol, under certain conditions, could stimulate liver proliferation triggered by PH. The mechanism underlying this surprising effect of ethanol on LR remains to be elucidated. However, it is suggested that an altered ethanol metabolism by rats subjected to PH could be involved.  相似文献   
956.
Spontaneous bacterial peritonitis (SBP) is a frequent infection in cirrhotic patients with ascites, with a poor prognosis. The aims of this study were to determine the long-term survival of cirrhotic patients with SBP treated with ceftriaxone and to identify predictive factors related to survival. We studied 47 first episodes of SBP treated with ceftriaxone with a mean follow-up of 272 days. Nineteen variables were recorded to evaluate their relation to survival. The most frequent organism that caused SBP was Escherichia coli (40%). Spontaneous bacterial peritonitis resolution was achieved in 67% of patients. After resolution, SBP recurrence was observed in 44% of patients. The cumulative probability of survival was 68.1% at 1 month and 30.8% at 6 months. After uni-and multivariate analyses of all cases, SBP resolution ( p = 0.0001) and international normalized ratio (INR) ( p = 0.0057) were found to be related to survival. Another analysis performed after SBP resolution and SBP recurrence showed that ascitic fluid-positive culture ( p = 0.0344) and INR ( p = 0.0218) had statistical significance as variables predictive of long-term survival. We conclude that the survival of cirrhotic patients is very short after the first episode of SBP, a fact probably related to advanced liver disease, as liver dysfunction (INR) is the most important factor related to long-term patient survival.  相似文献   
957.
958.
959.
960.
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