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   270425篇
  免费   19526篇
  国内免费   1161篇
耳鼻咽喉   3162篇
儿科学   7067篇
妇产科学   4922篇
基础医学   35719篇
口腔科学   5014篇
临床医学   26961篇
内科学   57073篇
皮肤病学   3752篇
神经病学   26223篇
特种医学   9312篇
外国民族医学   23篇
外科学   41305篇
综合类   3627篇
一般理论   323篇
预防医学   22748篇
眼科学   7238篇
药学   18251篇
  4篇
中国医学   400篇
肿瘤学   17988篇
  2023年   1247篇
  2022年   1945篇
  2021年   5711篇
  2020年   3419篇
  2019年   5532篇
  2018年   6224篇
  2017年   4691篇
  2016年   5209篇
  2015年   6135篇
  2014年   8996篇
  2013年   12370篇
  2012年   18820篇
  2011年   19687篇
  2010年   11055篇
  2009年   9888篇
  2008年   17352篇
  2007年   18261篇
  2006年   18067篇
  2005年   18026篇
  2004年   16909篇
  2003年   15692篇
  2002年   14753篇
  2001年   2793篇
  2000年   2307篇
  1999年   2929篇
  1998年   3310篇
  1997年   2789篇
  1996年   2379篇
  1995年   2263篇
  1994年   1894篇
  1993年   1700篇
  1992年   1669篇
  1991年   1577篇
  1990年   1410篇
  1989年   1343篇
  1988年   1354篇
  1987年   1282篇
  1986年   1292篇
  1985年   1263篇
  1984年   1456篇
  1983年   1300篇
  1982年   1497篇
  1981年   1437篇
  1980年   1272篇
  1979年   921篇
  1978年   909篇
  1977年   798篇
  1976年   731篇
  1975年   622篇
  1974年   647篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Carotid body tumors: a subject review and suggested surgical approach   总被引:1,自引:0,他引:1  
Carotid body tumors are a rare but potentially difficult surgical entity. Their pathology, physiology, and natural history are reviewed along with surgical results reported in the literature. A surgical approach for removal of these tumors is presented which differs significantly from the recommended techniques in that emphasis is placed on intraoperative monitoring of cerebral blood flow, the the selective use of shunts, a tumor-adventitial plane of dissection, preservation of the carotid artery complex, and mobilization of the parotid gland. Thirteen cases using these techniques are reviewed. The mortality rate and the incidence of cerebrovascular sequelae were both 0%. The major morbidity consisted of injury to the lower cranial nerves in five patients (39%) with tumors larger than 5 cm in length.  相似文献   
992.
Thrombosis of the axillary vein occurred in two patients following creation of an arteriovenous fistula for hemodialysis. The thrombosis developed before the fistula was used for dialysis, and was demonstrated by venography. Treatment in both cases involved anticoagulant therapy and ligation of the fistula; both patients experienced relief of pain and swelling, although the collateral venous congestion remained unchanged. This complication of arteriovenous fistula creation has not been previously described, probably because thrombosis does not usually occur in a high venous flow state.  相似文献   
993.
994.
OBJECTIVE: Transmission of bacterial and viral pathogens is known to occur by hand contact with fomites. Exercise equipment in public facilities may serve as such fomites. It is not known whether equipment disinfection might reduce microorganism colonization. We performed studies to address these issues. DESIGN: Observational study of bacterial and viral culture results from hand-contact surfaces of exercise equipment, pre-exercise and postexercise; prospective study of viral culture results before and after intervention with disinfection solution. SETTING: Two fitness centers in a military community. INTERVENTION: One week trial of twice-a-day equipment disinfection. MAIN OUTCOME MEASURES: Type and number of bacteria and type of viruses present on equipment before and after exercise; prevalence of viral culture positivity on equipment before and after intervention. RESULTS: Bacterial cultures of body contact surfaces on equipment revealed benign bacterial species (coagulase-negative staphylococci, diphtheroids, and so forth) but no pathogenic bacteria whether obtained pre-exercise or postexercise, or whether from aerobic versus weight training equipment. Viral cultures revealed the presence of viruses (generally rhinoviruses) on 63 of 100 (63%) hand-contact surfaces of equipment. Weight equipment was significantly more often contaminated than aerobic equipment (73% vs. 51%; P = 0.026). Disinfection of equipment did not lower the prevalence of virus isolation (48% positive before cleaning; 86% positive after cleaning). CONCLUSIONS: There is little risk of exposure to pathogenic bacteria on exercise equipment. Such equipment may commonly serve as fomites for the transmission of viruses. These data do not suggest that disinfection of exercise equipment will offer significant protective effects against virus exposure.  相似文献   
995.
996.
997.
Seronegative hepatitis is a common cause of acute liver failure (ALF) requiring liver transplantation. The primary aim of this study was to examine outcomes following transplantation in this group and to identify factors associated with early (<2 months) mortality. Patients studied were 110 consecutive cases of seronegative ALF transplanted at the Queen Elizabeth Hospital, Birmingham, between January 1992 and January 2004. Univariate analysis of 44 pretransplantation recipient, donor, and operative variables was performed initially to identify factors associated with early posttransplantation mortality. Variables identified as significant or approaching significance were analyzed using stepwise multiple logistic regression analysis. Survival following transplantation for seronegative hepatitis was 83%, 81%, and 73% at 2, 12, and 60 months, respectively. The majority (71%) of deaths occurred within the 1st 2 months and sepsis / multiorgan dysfunction was the most common cause of early death. Univariate analysis revealed 9 variables predicting early death. Subsequent multivariate analysis identified high donor body mass index (BMI; a possible surrogate marker for hepatic steatosis) as the most important predictor of early death (P = .009; odds ratio, 1.2; 95% confidence interval, 1.0-1.3). Recipient age >50 (P = .015; odds ratio, 4.2; 95% confidence interval, 1.3-14.1) and non-Caucasian recipient ethnicity (P = .015; odds ratio, 4.9; 95% confidence interval, 1.2-19.2) were other variables associated with early death on multivariate analysis. This study specifically examined factors that determine the early outcome of transplanted seronegative ALF patients. In conclusion, we found that donor and recipient factors identify patients who have a high chance of early death after transplantation.  相似文献   
998.
999.
1000.
PURPOSE: Postoperative nausea and vomiting (PONV) is the most common postoperative complication after surgery and general anesthesia. PONV occurs primarily within the first 24 hours and can lead to significant morbidity, delayed hospital discharge, increased hospital costs and perhaps most importantly, poor patient satisfaction. We sought, in this study, to determine the prevalence of PONV and to identify risk factors in patients who underwent orthognathic surgery. PATIENTS AND METHODS: We conducted a retrospective cross-sectional analytic survey of 553 consecutive patients over 14 years of age, who underwent maxillary and/or mandibular osteotomies at Kaiser Permanente Hospital (Oakland, CA), between January 2003 and March 2004. Patient-, anesthesia- and surgery-related factors that were considered to have a possible effect on the prevalence of PONV events were evaluated. RESULTS: A total of 514 patients met the inclusion criteria. Among these patients, 40.08% experienced PONV during the first 24 hours after surgery. The most important predictive factors associated with an increased risk of PONV were female gender, young patients (15 to 25 years old), nonsmoking status, presence of predisposing factors (ie, prior history of motion sickness and/or PONV, vertigo or migraine headaches), use of volatile general anesthetics, maxillary surgery, postoperative pain level (PACU) and the use of postoperative analgesic opioid drugs. We found a directly proportional relationship between the number of risk factors and the prevalence of PONV. CONCLUSION: We found PONV had a high prevalence among patients undergoing orthognathic surgery. Further studies are needed to develop effective protocols for preventing this common and unpleasant problem.  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