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   23248篇
  免费   3167篇
  国内免费   492篇
耳鼻咽喉   236篇
儿科学   564篇
妇产科学   208篇
基础医学   1347篇
口腔科学   251篇
临床医学   1567篇
内科学   2043篇
皮肤病学   729篇
神经病学   491篇
特种医学   3628篇
外国民族医学   21篇
外科学   1709篇
综合类   2548篇
现状与发展   3篇
预防医学   2231篇
眼科学   233篇
药学   2807篇
  17篇
中国医学   554篇
肿瘤学   5720篇
  2024年   54篇
  2023年   384篇
  2022年   701篇
  2021年   967篇
  2020年   907篇
  2019年   888篇
  2018年   979篇
  2017年   937篇
  2016年   1031篇
  2015年   1035篇
  2014年   1780篇
  2013年   2170篇
  2012年   1509篇
  2011年   1551篇
  2010年   1161篇
  2009年   1035篇
  2008年   1057篇
  2007年   977篇
  2006年   880篇
  2005年   768篇
  2004年   674篇
  2003年   611篇
  2002年   526篇
  2001年   486篇
  2000年   397篇
  1999年   355篇
  1998年   291篇
  1997年   287篇
  1996年   264篇
  1995年   212篇
  1994年   187篇
  1993年   176篇
  1992年   139篇
  1991年   162篇
  1990年   136篇
  1989年   155篇
  1988年   125篇
  1987年   113篇
  1986年   105篇
  1985年   147篇
  1984年   112篇
  1983年   83篇
  1982年   85篇
  1981年   65篇
  1980年   70篇
  1979年   61篇
  1978年   21篇
  1977年   33篇
  1976年   24篇
  1975年   14篇
排序方式: 共有10000条查询结果,搜索用时 93 毫秒
111.
Changing community attitudes are leading to a wider acceptance of the need for continuing education. Universities offering professional degree courses have a responsibility for continuing education in the subject-areas covered by their undergraduate curricula, which could be discharged in one or more ways, e.g. short refresher courses to keep practitioners abreast of developing theory and practice, or longer recurrent study programs leading to further formal qualifications. However the responsibility for continuing education must be shared by employing agencies and professional societies. The Institute of Foresters in particular should be concerned with ensuring that adequate opportunities exist for further education of its corporate membership. The needs and likely demands of foresters for continuing education are considered, and suggestions outlined for future developments.  相似文献   
112.
Even though some of the questions about the role of diet in heart disease are still unanswered, it is clear that obesity, diabetes, and hyperlipidemia increase the risk of heart disease. Physicians who would prevent arteriosclerosis in their patients are directing attention to dietary modification for young adults and children.  相似文献   
113.
Background. High dose insulin (HDI) has proven superior to glucagon and catecholamines in the treatment of poison-induced cardiogenic shock (PICS) in previous animal studies. Standard recommendations for dosing of insulin vary and the optimal dose of HDI in PICS has not been established. Our hypothesis was a dose of 10 U/kg/hr of HDI would be superior to 1 U/kg/hr with cardiac output (CO) as our primary outcome measure in pigs with propranolol-induced PICS. Methods. This was a blinded, prospective, randomized trial with 4 arms consisting of 4 pigs in each arm. The arms were as follows: placebo (P), 1 U/kg/hr (HDI-1), 5 U/kg/hr (HDI-5), and 10 U/kg/hr (HDI-10). Cardiogenic shock was induced with a bolus of 0.5 mg/kg of propranolol followed by an infusion of 0.25 mg/kg/min until the point of toxicity, defined as 0.75 x (HR x MAP) was reached. At this point the propranolol infusion was decreased to 0.125 mg/kg/min and a 20 mL/kg bolus of normal saline (NS) was administered. The protocol was continued for 6 hours or until the animals died. Results. 2 pigs died in the P arm, 1 pig died each in the HDI-1 and HDI-5 arms, and all pigs lived in the HDI-10 arm. There was a statistically significant difference in dose by time interaction on CO of 1.13 L/min over the 6 hr study period (p = < 0.001). There was also a statistically significant difference in dose by time interaction on MAP, HR, and systemic vascular resistance (SVR). No statistically significant difference was found between any of the arms regarding glucose utilization. Conclusion. HDI was statistically and clinically significantly superior to placebo in this propranolol model of PICS. Furthermore a dose response over time was found where CO increased corresponding to increases in doses of HDI.  相似文献   
114.
115.
双源CT低管电压降低冠状动脉CTA辐射剂量   总被引:4,自引:3,他引:4  
目的 观察低管电压在体质指数(BMI)正常范围患者双源CT冠状动脉成像(CTA)中的应用,并评价其图像质量.方法 将65例BMI在正常范围并接受冠状动脉CTA检查的患者随机分为两组,A组管电压采用常规扫描120 kV,B组管电压采用100 kV,均采用回顾性心电门控螺旋扫描.对两组扫描的冠状动脉分别做图像处理,应用秩和检验比较两组患者冠状动脉段图像质量总体评分,两独立样本t检验比较两组患者的辐射剂量和对比剂用量. 结果 A组评价443段冠状动脉,B组评价451段冠状动脉.A组图像质量评价为优和良好的占97.74%,B组占97.56%.冠状动脉段图像质量评分两组之间比较差异无统计学意义(P=0.126).A组平均有效剂量为(15.04±2.42)mSv;B组平均有效剂量为(7.95±1.69)mSv,差异有统计学意义(P<0.001).A组对比剂用量为(75.17±3.69)ml,B组对比剂用量为(62.27±3.42)ml,差异有统计学意义(P<0.001). 结论 对于BMI在正常范围内的患者,冠状动脉CTA检查时管电压设为100 kV可在保证图像质量的同时显著降低辐射剂量和对比剂用量.  相似文献   
116.
In order to assess ileal dysfunction in patients with complaints after pelvic radiation therapy, retention measurements and scintigraphic imaging with selenium 75 homocholic acid conjugated with taurine (75Se-HCAT), combined with the carbon 14 glycochol breath test, were evaluated in 39 patients. In 22 patients without ileal resection the results of the75Se-HCAT test and the breath test differentiated between a normal functioning ileum (both tests negative) and ileal dysfunction as a cause of complaints (one or both tests positive). Among the patients with ileal dysfunction, the combination of both tests permitted those with bacterial overgrowth (breath test positive,75Se-HCAT negative) to be separated from patients with evidence of bile acid malabsorption (75Se-HCAT positive, breath test positive or negative). In 17 patients with small-bowel resection, the75Se-HCAT test helped to estimate the severity of bile acid malabsorption with implications for therapy. In this group the breath test was false-negative in 7 cases with abnormal75Se-HCAT. Additional systematically performed scintigraphic imaging improved the accuracy of the75Se-HCAT test, revealing cases with prolonged colonic accumulation of the radiopharmaceutical, causing spurious retention values. In conclusion, assessment of ileal dysfunction by nuclear medicine techniques in post-irradiation conditions provides information about the aetiology and therefore the possibility of adjustment in the clinical management. Offprint requests to: R.A. Valdes Olmos  相似文献   
117.
Forty patients with carcinoma of the rectum or rectosigmoid underwent preoperative irradiation, followed by anterior resection with anastomosis. The radiation dose was 4500 rads administered in 25 fractions over a period of five weeks. One to three weeks after the radiation was completed, anterior resection of the rectosigmoid with anastomosis was done. Of the 40 patients, 23 had hand-sewn anastomoses and 17 had EEA stapled anastomoses. Fourteen of the 40 had diverting loop colostomies, all colostomies were subsequently closed, and there were no clinical postoperative anastomotic leaks. Anterior resection and anastomosis are considered to be technically safe with the surgical and radiation techniques used. Read at the joint meeting of the American Society of Colon and Rectal Surgeons with the Section of Colo-Proctology, Royal Society of Medicine, and the Section of Colonic and Rectal Surgery, Royal Australasian College of Surgeons, New Orleans, Louisiana, May 6 to 11, 1984.  相似文献   
118.
There is enough evidence to show that adjuvant radiation therapy contributes to the management of patients with carcinoma of the rectum. In an effort to improve resectability and possibly survival rates, the use of chemosensitizers, combined with moderate doses of radiation used presurgically, was introduced for carcinomas larger than 5 cm in diameter requiring abdominoperineal resection. Based on our experience and that of others, it is believed that the method of administration of 5FU and mitomycin-C is an important factor in obtaining an increased therapeutic ratio. Because of the locoregional pattern of spread of rectal cancer, this adjuvant approach would appear suitable. A series of approximately 60 patients is discussed and the surgical findings and five-year survival is reported. Read at the Joint Meeting of the American Society of Colon and Rectal Surgeons with the Section of Colo-Proctology, Royal Society of Medicine, and the Section of Colonic and Rectal Surgery, Royal Australasian College of Surgeons, New Orleans, Louisiana, May 6 to 11, 1984.  相似文献   
119.
Dipetalonema viteae (Filarioidea) infections were established in inbred strains of mice by the s.c. implantation of adult female worms and the resulting microfilaraemia and adult worm survival monitored. BALB/c mice were the most susceptible strain examined, showing a high level microfilaraemia of approximately 6 month's duration. C57Bl/10, CBA/Ca and C3H/He mice were all equally resistant to infection, showing a low level of microfilaraemia of approximately 1 month's duration. The response of NIH mice was intermediate. Relatively little strain difference was seen in adult worm survival although worms lived slightly longer in C57Bl/10 mice than in BALB/c mice. The adult females became depleted of microfilariae over a period of approximately 1 month before becoming encapsulated in host tissue. Challenge infections given to mice previously implanted with worms resulted in lower level, shorter lasting microfilaraemias than those seen in the initial primary infections. All strains showed immunity when challenged. High responsiveness (resistance) was inherited as a dominant trait in F1 hybrids produced by crossing high and low responder strains. Genes linked with the major histocompatibility complex (H-2) were found to have no effect on the response phenotype as demonstrated by the similar responses of H-2 congenic mice on the BALB/c or C57bl/10 backgrounds. The response phenotype of radiation chimaeras was determined by the phenotype of the donor from which bone marrow (BM) cells were taken for reconstitution. Susceptible BALB/c mice reconstituted with resistant B10D2/n BM behaved identically to the donor strain, indicating that the genetic variation which exists between mouse strains in their responses to D. viteae is expressed through a population of BM derived cells and is not simply a consequence of host structure or physiology.  相似文献   
120.
低剂量辐射诱导免疫适应性反应的最佳时间   总被引:6,自引:1,他引:6       下载免费PDF全文
本实验观察了低剂量X射线全身单次照射诱导昆明小鼠免疫适应性反应的最佳时间.证实当预照射剂量(D_1剂量)为75mGy.剂量率12.5mGy/min,损伤剂量(D_2剂量)为1.5Gy,剂量率0.33Gy/min,D_1与D_2间隔6h可诱导脾细胞对脂多糖反应的适应性反应,D_1与D_2间隔12h可诱导胸腺细胞自发增殖及脾细胞对ConA及脂多糖反应的适应性反应.以上结果表明,当D_2为1.5Gy时。75mGy诱导上述免疫适应性反应的最佳时间间隔为6h及12h.  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