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   3015篇
  免费   134篇
  国内免费   7篇
耳鼻咽喉   59篇
儿科学   67篇
妇产科学   32篇
基础医学   605篇
口腔科学   158篇
临床医学   351篇
内科学   518篇
皮肤病学   119篇
神经病学   210篇
特种医学   119篇
外科学   347篇
综合类   29篇
预防医学   161篇
眼科学   62篇
药学   200篇
中国医学   4篇
肿瘤学   115篇
  2022年   30篇
  2021年   58篇
  2020年   31篇
  2019年   37篇
  2018年   29篇
  2017年   35篇
  2016年   39篇
  2015年   56篇
  2014年   55篇
  2013年   74篇
  2012年   115篇
  2011年   116篇
  2010年   60篇
  2009年   78篇
  2008年   136篇
  2007年   146篇
  2006年   151篇
  2005年   152篇
  2004年   117篇
  2003年   161篇
  2002年   135篇
  2001年   109篇
  2000年   101篇
  1999年   99篇
  1998年   26篇
  1997年   37篇
  1996年   26篇
  1995年   20篇
  1993年   20篇
  1992年   51篇
  1991年   37篇
  1990年   48篇
  1989年   54篇
  1988年   38篇
  1987年   32篇
  1986年   34篇
  1985年   33篇
  1984年   22篇
  1979年   20篇
  1976年   21篇
  1974年   24篇
  1973年   21篇
  1972年   21篇
  1970年   22篇
  1885年   18篇
  1880年   32篇
  1879年   21篇
  1877年   21篇
  1876年   21篇
  1875年   18篇
排序方式: 共有3156条查询结果,搜索用时 31 毫秒
71.

Background

Crowd crushes with dozens or even hundreds of casualties have occurred several times at the Hajj in Saudi Arabia and also in soccer stadiums in Western Europe. As fatal accidents after human stampedes during mass events occur very rarely and are usually accompanied by many years of criminal court proceedings in order to identify underlying responsible mechanisms and culprits, it is very difficult to draw conclusions and formulate precautions from an emergency medical point of view.

Methods

This study analyzed a fatal crowd crush which occurred on 4 December 1999 following the “Air & Style” snowboard contest with approximately 22,000 people attending in the Bergisel stadium in Innsbruck, Austria. Firstly, focused interviews were conducted with professional rescuers, police and physicians and secondly publicly available court records dealing with this incident in the district court of Innsbruck, Austria were analyzed.

Results

During the snowboard contest 87 emergency medical technicians, 6 emergency physicians, 1 leading emergency physician, 21 policemen and 140 security personnel were present. Following the accident additionally some 100 emergency medical technicians, 36 emergency medical service vehicles and 4 physician-staffed emergency medical service vehicles responded to the scene. The deadly crowd crush resulting in 6 fatalities, 4 patients still in a vegetative state and 38 injured, was due to a severe crowd accumulation at one stadium exit, which was not recognized and dispersed in time. Construction of the exit in line with darkness, steep slope and slippery surface contributed adversely to this dangerous situation, although panic did not occur at any time.

Conclusions

Unfortunately, there is no patent remedy to completely prevent fatal accidents by a crowd crush at mass events. If planning is initiated early, sufficient material and personnel reserves are kept in reserve and despite conflicting interests of the organizers, the host community, security, police and emergency medical services, a joint concept is designed and followed, the risk of a severe incident can be kept to a minimum. Each involved party including the spectators have to be aware of their responsibility in order to contribute to the success and safety of the mass event. A comprehensive and critical review of all facts and implementation of conclusions implies a time and financial burden but has a positive impact on the success and safety of mass events.  相似文献   
72.
All deleterious changes in platelet morphology, structure and function that occur in platelet concentrates (PC) during storage are titled as the 'platelet storage lesion'. No single in?vitro test currently available is sufficient in assessing these changes of platelet quality. The release of soluble CD40 Ligand (sCD40L), the formation of thromboxane (TXB2) and the thrombopoietin (TPO) clearance reflect different aspects of platelet metabolism and activitiy, and were used to examine platelet quality in apheresis platelet products. At days 1, 3 and 5, in single-donor apheresis platelet products (n?=?10) under routine storage conditions, sCD40L (measured by ELISA) and TXB2 (measured by RIA) were determined after platelet stimulation (recalcification and clot formation). TPO (measured by ELISA) was determined after an incubation time of 5?h at 37°C with platelet-rich plasma (adjusted initial TPO concentration of about 500?pg/mL). Results were related to a therapeutic unit (TU?=?2?×?10(11)?platelets). Immediately after platelet preparation, sCD40L release was 41?±?7.6?ng/TU, TXB2 formation 1688?±?374?ng/TU and TPO clearance 1.22?±?0.32?ng/h/TU. At days 1, 3 and 5, sCD40L was reduced to 89?±?7%, 71?±?12% and 57?±?9%, TXB2 release to 91?±?6%, 74?±?12% and 58?±?9% and TPO clearance to 90?±?15%, 84?±?5% and 79?±?10% of the respective control values. In conclusion, in single-donor apheresis PC, sCD40L release and TXB2 formation as well as TPO clearance by the platelets were dependent on storage duration and reduced to about 60% to 80% of the respective control values after a storage period for 5 days. These findings are in line with literature data, indicating that a loss of platelet functionality of about 30% will occur after 5 days of storage.  相似文献   
73.
74.
Asthma, and severe asthma, in particular, is increasingly recognized as a heterogeneous disease. While traditional views of asthma have centered around a childhood onset disease with an allergic component, several large scale network studies are now confirming that severe asthma can present in multiple different ways, only 30-50% of which meet traditional childhood onset allergic criteria. To understand the different groups better, initial studies have attempted to define phenotypes of severe asthma. A phenotype is defined as the integration of different characteristics that are the product of the interaction of the patient's genes with the environment. Both clinical and statistical approaches have identified at least 3-5 phenotypes of severe asthma. However, these phenotypes, in isolation, do not identify the immunopathology that makes these clinical phenotypes distinct or identifies a target population for a specific approach to therapy. As biological characteristics are identified, phenotypes should continue to evolve towards asthma endotypes. The identification of these endotypes, either by matching biology, genetics and therapeutic responses to therapy with clinically or statistically defined phenotypes or through unbiased genetic and genomic approaches, remains limited. Moving forward, this integration of genetics, biology and clinical characteristics should substantially enhance our ability to effectively treat complex heterogeneous diseases, such as severe asthma.  相似文献   
75.
76.
Baelum V, Hintze H, Wenzel A, Danielsen B, Nyvad B. Implications of caries diagnostic strategies for clinical management decisions. Community Dent Oral Epidemiol 2011. © 2011 John Wiley & Sons A/S Abstract – Objectives: In clinical practice, a visual–tactile caries examination is frequently supplemented by bitewing radiography. This study evaluated strategies for combining visual–tactile and radiographic caries detection methods and determined their implications for clinical management decisions in a low‐caries population. Methods: Each of four examiners independently examined preselected contacting interproximal surfaces in 53 dental students aged 20–37 years using a visual–tactile examination and bitewing radiography. The visual–tactile examination distinguished between noncavitated and cavitated lesions while the radiographic examination determined lesion depth. Direct inspection of the surfaces following tooth separation for the presence of cavitated or noncavitated lesions was the validation method. The true‐positive rate (i.e. the sensitivity) and the false‐positive rate (i.e. 1‐specificity) were calculated for each diagnostic strategy. Results: Visual–tactile examination provided a true‐positive rate of 34.2% and a false‐positive rate of 1.5% for the detection of a cavity. The combination of a visual–tactile and a radiographic examination using the lesion in dentin threshold for assuming cavitation had a true‐positive rate of 76.3% and a false‐positive rate of 8.2%. When diagnostic observations were translated into clinical management decisions using the rule that a noncavitated lesion should be treated nonoperatively and a cavitated lesion operatively, our results showed that the visual–tactile method alone was the superior strategy, resulting in most correct clinical management decisions and most correct decisions regarding the choice of treatment.  相似文献   
77.
The increasing concerns on uranium and rare earth metal ion pollution in the environment require sustainable strategies to remove them from wastewater. The present study reports an eco-friendly approach to convert a kind of protein-rich biomass, brewer''s spent grain (BSG), into effective biosorbents for uranyl and rare earth metal ions. The employed method reduces the energy consumption by performing the hydrothermal treatment at a significantly lower temperature (150 °C) than conventional hydrothermal carbonization. In addition, with the aid of the Maillard reaction between carbohydrates and proteins forming melanoidins, further activation processes are not required. Treatment at 150 °C for 16 h results in an altered biosorbent (ABSG) with increased content of carboxyl groups (1.46 mmol g−1) and a maximum adsorption capacity for La3+, Eu3+, Yb3+ (pH = 5.7) and UO22+ (pH = 4.7) of 38, 68, 46 and 221 mg g−1, respectively. Various characterization methods such as FT-IR, 13C CP/MAS NMR, SEM-EDX and STA-GC-MS analysis were performed to characterize the obtained material and to disclose the adsorption mechanisms. Aside from oxygen-containing functional groups, nitrogen-containing functional groups also contribute to the adsorption. These results strongly indicate that mild hydrothermal treatment of BSG could be applied as a greener, low-cost method to produce effective adsorbents for uranyl and rare earth metal ion removal.

Effective biosorbent ABSG is obtained via hydrothermal treatment of BSG at low temperature without activation, minimizing energy consumption and environmental impact.  相似文献   
78.
BACKGROUND: IgE-mediated responses contribute to allergy and asthma. Little is understood regarding the relationship of tissue IgE to systemic IgE, inflammation or clinical outcomes. OBJECTIVES: To evaluate local IgE expression and cellular inflammation in the proximal and distal lung of normal subjects and subjects with asthma of varying severity and relate those tissue parameters to systemic IgE levels, atopy, lung function, and history of severe exacerbations of asthma. METHODS: Tissue from more than 90 subjects with eosinophilic (SAeo(+)) and noneosinophilic (SAeo(-)) severe asthma, mild asthma and normal subjects were immunostained for IgE, signal-amplifying isoform of IgE receptor (FcepsilonRIbeta) and markers of mast cells, eosinophils, and lymphocytes. Tissue expression of IgE, FcepsilonRIbeta, cellular inflammation, serum IgE, and atopy were compared. Regression models were used to determine the relationship of local and systemic IgE to lung function and severe exacerbations of asthma. RESULTS: Mast cell-bound IgE was present along airways but absent in lung parenchyma. Although the groups were similar in systemic/serum IgE and atopy, local/tissue IgE was highest in SAeo(+) and correlated with eosinophils and lymphocytes (r(s) = 0.52, P < .0001; and r(s) = 0.23, P = .03, respectively). Higher local IgE was associated with better lung function, but also with more severe exacerbations of asthma. CONCLUSION: Local IgE appears to be primarily a component of responses within the mucosal immune compartment and is related to cellular inflammation, lung function, and clinical outcomes in asthma. CLINICAL IMPLICATIONS: Local/airway IgE-related processes rather than systemic markers of atopy may be relevant in determining clinical outcomes in asthma.  相似文献   
79.
Possible unwanted folding of biopharmaceuticals during manufacturing and storage has resulted in analysis schemes compared to small molecules that include bioanalytical characterization besides chemical characterization. Whether bioanalytical characterization is required for nucleotide-based drugs, may be decided on a case-by-case basis. Nucleotide-based pharmaceuticals, if chemically synthesized, occupy an intermediate position between small-molecule drugs and biologics. Here, we tested whether a physicochemical characterization of a nucleotide-based drug substance, BC 007, was adequate, using circular dichroism (CD) spectroscopy. Nuclear magnetic resonance confirmed CD data in one experimental setup. BC 007 forms a quadruplex structure under specific external conditions, which was characterized for its stability and structural appearance also after denaturation using CD and nuclear magnetic resonance. The amount of the free energy (ΔG0) involved in quadruplex formation of BC 007 was estimated at +8.7 kJ/mol when dissolved in water and +1.4 kJ/mol in 154 mM NaCl, indicating structural instability under these conditions. However, dissolution of the substance in 5 mM of KCl reduced the ΔG0 to ?5.6 kJ/mol due to the stabilizing effect of cations. These results show that positive ΔG0 of quadruplex structure formation in water and aqueous NaCl prevents BC 007 from preforming stable 3-dimensional structures, which could potentially affect drug function.  相似文献   
80.
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