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   7629篇
  免费   417篇
  国内免费   44篇
耳鼻咽喉   81篇
儿科学   188篇
妇产科学   180篇
基础医学   1095篇
口腔科学   323篇
临床医学   628篇
内科学   1380篇
皮肤病学   117篇
神经病学   761篇
特种医学   507篇
外科学   1120篇
综合类   34篇
一般理论   2篇
预防医学   394篇
眼科学   209篇
药学   530篇
中国医学   14篇
肿瘤学   527篇
  2023年   42篇
  2022年   114篇
  2021年   206篇
  2020年   145篇
  2019年   170篇
  2018年   180篇
  2017年   167篇
  2016年   223篇
  2015年   252篇
  2014年   312篇
  2013年   462篇
  2012年   592篇
  2011年   585篇
  2010年   355篇
  2009年   314篇
  2008年   512篇
  2007年   497篇
  2006年   446篇
  2005年   425篇
  2004年   367篇
  2003年   363篇
  2002年   355篇
  2001年   69篇
  2000年   49篇
  1999年   59篇
  1998年   54篇
  1997年   40篇
  1996年   55篇
  1995年   51篇
  1994年   41篇
  1993年   30篇
  1992年   34篇
  1991年   27篇
  1990年   15篇
  1989年   20篇
  1988年   17篇
  1987年   27篇
  1986年   22篇
  1985年   30篇
  1984年   27篇
  1983年   19篇
  1982年   26篇
  1981年   17篇
  1980年   18篇
  1979年   14篇
  1978年   15篇
  1977年   16篇
  1974年   18篇
  1971年   13篇
  1967年   17篇
排序方式: 共有8090条查询结果,搜索用时 15 毫秒
141.
142.
Sedation for burn patients is provided by a variety of techniques determined usually by institutional preferences. The available pool of drugs has recently expanded to include dexmedetomidine (DEX), a α2-adrenergic receptor agonist with analgesic and sedative potential. Beneficial effects of DEX in burn patients have been described in many studies published over the last 5 years. The aim of this study is to perform a systematic review and meta-analysis of the available literature to determine the role of DEX for analgosedation of burn patients. We searched any article that matched the keywords “dexmedetomidine” and “burn”, published before October 01, 2012. The methodological quality of studies was assessed using the recommendation of the Oxford Centre for Evidence Based Medicine (OCEBM). Our search yielded eleven total citations, of which four studies (266 patients) met the inclusion criteria of DEX for analgosedation in burn patients. There are no meta-analyses published that met our inclusion criteria. Even though there were only a small number of clinical trials available, the meta-analysis shows evidence for deeper and better sedation as well as for prevention of hypertension when using DEX as an adjunct during burn procedures. No evidence was found for reduced pain scores in this setting. The authors recommend the development of a prospective, randomized, controlled multicenter trial with an adequate number of patients to further elucidate the potentially beneficial effects of DEX for the management of burn patients.  相似文献   
143.
A systematic review and meta-analysis was conducted to assess the level of evidence for the use of extracorporeal membrane oxygenation (ECMO) in hypoxemic respiratory failure resulting from burn and smoke inhalation injury. We searched any article published before March 01, 2012. Available studies published in any language were included. Five authors rated each article and assessed the methodological quality of studies using the recommendation of the Oxford Centre for Evidence Based Medicine (OCEBM). Our search yielded 66 total citations but only 29 met the inclusion criteria of burn and/or smoke inhalation injury. There are no available systematic reviews/meta-analyses published that met our inclusion criteria. Only a small number of clinical trials, all with a limited number of patients, were available. The overall data suggests that there is no improvement in survival for burn patients suffering acute hypoxemic respiratory failure, with the use of ECMO. ECMO run times of less than 200 h correlate with higher survival compared to 200 h or more. Scald burns show a tendency of higher survival than flame burns.  相似文献   
144.

Background

The fields of surgery and trauma care have largely been neglected in the global health discussion. As a result the idea that surgery is not safe or cost effective in resource-limited settings has gone unchallenged. The SIGN Online Surgical Database (SOSD) is now one of the largest databases on trauma surgery in low- and middle-income countries (LMIC). We wished to examine infection rates and risk factors for infection after IM nail operations in LMIC using this data.

Methods

The SOSD contained 46,722 IM nail surgeries in 58 different LMIC; 46,113 IM nail operations were included for analysis.

Results

The overall follow-up rate was 23.1 %. The overall infection rate was 1.0 %, 0.7 % for humerus, 0.8 % for femur, and 1.5 % for tibia fractures. If only nails with registered follow-up (n = 10,684) were included in analyses, infection rates were 2.9 % for humerus, 3.2 % for femur, and 6.9 % for tibia fractures. Prophylactic antibiotics reduced the risk of infection by 29 %. Operations for non-union had a doubled risk of infection. Risk of infection was reduced with increasing income level of the country.

Conclusions

The overall infection rates were low, and well within acceptable levels, suggesting that it is safe to do IM nailing in low-income countries. The fact that operations for non-union have twice the risk of infection compared to primary fracture surgery further supports the use of IM nailing as the primary treatment for femur fractures in LMIC.  相似文献   
145.
146.
Background contextClosed reduction and internal fixation by an anterior approach is an established option for operative treatment of displaced Type II odontoid fractures. In elderly patients, however, inadequate screw purchase in osteoporotic bone can result in severe procedure-related complications.PurposeTo improve the stability of odontoid fracture screw fixation in the elderly using a new technique that includes injection of polymethylmethacrylat (PMMA) cement into the C2 body.Study designRetrospective review of hospital and outpatient records as well as radiographs of elderly patients treated in a university hospital department of orthopedic surgery.Patient sampleTwenty-four elderly patients (8 males and 16 females; mean age, 81 years; range, 62–98 years) with Type II fractures of the dens.Outcome measuresComplications, cement leakage (symptomatic/asymptomatic), operation time, loss of reduction, pseudarthrosis and revision surgery, patient complaints, return to normal activities, and signs of neurologic complications were all documented.MethodsAfter closed reduction and anterior approach to the inferior border of C2, a guide wire is advanced to the tip of the odontoid under biplanar fluoroscopic control. Before the insertion of one cannulated, self-drilling, short thread screws, a 12 gauge Yamshidi cannula is inserted from anterior and 1 to 3 mL of high-viscosity PMMA cement is injected into the anteroinferior portion of the C2 body. During polymerization of the cement, the screws are further inserted using a lag-screw compression technique. The cervical spine then is immobilized with a soft collar for 8 weeks postoperatively.ResultsAnatomical reduction of the dens was achieved in all 24 patients. Mean operative time was 64 minutes (40–90 minutes). Early loss of reduction occurred in three patients, but revision surgery was indicated in only one patient 2 days after primary surgery. One patient died within the first eight postoperative weeks, one within 3 months after surgery. In five patients, asymptomatic cement leakage was observed (into the C1–C2 joint in three patients, into the fracture in two). Conventional radiologic follow-up at 2 and 6 months confirmed anatomical healing in 16 of the19 patients with complete follow-up. In two patients, the fractures healed in slight dorsal angulation; one patient developed a asymptomatic pseudarthrosis. All patients were able to resume their pretrauma level of activity.ConclusionsCement augmentation of the screw in Type II odontoid fractures in elderly patients is technically feasible in a clinical setting with a low complication rate. This technique may improve screw purchase, especially in the osteoporotic C2 body.  相似文献   
147.
148.

Objective

To analyse the association of direct and indirect costs in patients with medically unexplained symptoms (MUS) with somatic symptom severity (SSS).

Methods

A cross-sectional cost analysis for retrospective 6 months was conducted in 294 primary care patients with MUS. Health care utilisation and loss of productivity were measured by questionnaires. SSS was measured using the “Patient Health Questionnaire 15” (PHQ-15). Direct and indirect costs and the association of costs with SSS were analysed via multiple linear regression analysis.

Results

Patients with MUS had average 6-month direct costs of 1098 EUR and indirect costs of 7645 EUR. For direct costs, outpatient physician visits were the most expensive single cost category (36%), followed by pharmaceuticals (25%) and hospital stays (19%). Indirect costs were predominantly caused by productivity reduction at work (56%) followed by early retirement (29%) and acute sickness absence (14%). As compared to mild SSS, moderate SSS was not significantly associated with direct, but with indirect costs (+ 2948 EUR; p < .001); severe SSS was associated with increased direct cost (+ 658 EUR; p = .001) and increased indirect costs (+ 4630 EUR; p < .001). Age was positively associated with direct cost (+ 15 EUR for each additional year; p = .015) as well as indirect cost (+ 104 EUR for each additional year; p < .001).

Conclusions

MUS are associated with relevant direct and even much higher indirect costs that strongly depend on SSS.  相似文献   
149.
Mast cells (MCs) are densely granulated perivascular resident cells of hematopoietic origin and well known for their pathogenetic role in allergic and anaphylactic reactions. In addition, they are also involved in processes of innate and adaptive immunity. MCs can be activated in response to a wide range of stimuli, resulting in the release of not only pro-inflammatory, but also anti-inflammatory mediators. The patterns of secreted mediators depend upon the given stimuli and microenvironmental conditions, accordingly MCs have the ability to promote or attenuate inflammatory processes. Their presence in the central nervous system (CNS) has been recognized for more than a century. Since then a participation of MCs in various pathological processes in the CNS has been well documented. They can aggravate CNS damage in models of brain ischemia and hemorrhage, namely through increased blood–brain barrier damage, brain edema and hemorrhage formation and promotion of inflammatory responses to such events. In contrast, recent evidence suggests that MCs may have a protective role following traumatic brain injury by degrading pro-inflammatory cytokines via specific proteases. In neuroinflammatory diseases such as multiple sclerosis, the role of MCs seems to be ambiguous. MCs have been shown to be damaging, neuroprotective, or even dispensable, depending on the experimental protocols used. The role of MCs in the formation and progression of CNS tumors such as gliomas is complex and both positive and negative relationships between MC activity and tumor progression have been reported. In summary, MCs and their secreted mediators modulate inflammatory processes in multiple CNS pathologies and can thereby either contribute to neurological damage or confer neuroprotection. This review intends to give a concise overview of the regulatory roles of MCs in brain disease.  相似文献   
150.
Transient ischemia causes delayed neurodegeneration in selective brain areas, particularly in the CA1 field of the hippocampus. This is accompanied by neurovascular impairment. It is unknown whether neurodegeneration is the cause or consequence of vascular changes. In an entorhino-hippocampal-organotypic slice culture system with well-preserved blood vessels, we studied the interplay between neurodegeneration and neurovasculature. Short-term oxygen and glucose deprivation (OGD) resulted in upregulation of hypoxic markers and with a delay of 24 to 48 hours in selective nerve cell death in CA1. In parallel, local vessel density decreased as detected by markers of endothelial cells and of the extracellular matrix. Claudin-5, a tight junction protein and marker of the blood–brain barrier was reduced. Preventing neuronal death with tetrodotoxin or 6-cyano-7-nitroquinoxaline-2,3-dione rescued blood vessels, suggesting that vessel loss is not due to OGD per se but a consequence of neuronal death. Induction of excitotoxic neuronal death with AMPA caused widespread neurodegeneration, but vessel reduction was confined to CA1. In dentate gyrus without neuronal loss, vessel density increased. We propose that neuronal stress and death influence maintenance, loss and remodeling of the neurovasculature and that the type of vascular response is in addition determined by local factors within the hippocampus.  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