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   4067篇
  免费   321篇
  国内免费   18篇
耳鼻咽喉   86篇
儿科学   83篇
妇产科学   97篇
基础医学   518篇
口腔科学   120篇
临床医学   438篇
内科学   984篇
皮肤病学   51篇
神经病学   353篇
特种医学   187篇
外国民族医学   1篇
外科学   508篇
综合类   38篇
一般理论   1篇
预防医学   218篇
眼科学   31篇
药学   378篇
中国医学   3篇
肿瘤学   311篇
  2023年   43篇
  2022年   72篇
  2021年   167篇
  2020年   95篇
  2019年   154篇
  2018年   174篇
  2017年   143篇
  2016年   110篇
  2015年   152篇
  2014年   155篇
  2013年   205篇
  2012年   265篇
  2011年   249篇
  2010年   154篇
  2009年   122篇
  2008年   208篇
  2007年   178篇
  2006年   150篇
  2005年   161篇
  2004年   129篇
  2003年   95篇
  2002年   117篇
  2001年   74篇
  2000年   65篇
  1999年   74篇
  1998年   25篇
  1997年   26篇
  1996年   27篇
  1995年   30篇
  1994年   33篇
  1993年   33篇
  1992年   79篇
  1991年   66篇
  1990年   58篇
  1989年   53篇
  1988年   47篇
  1987年   45篇
  1986年   38篇
  1985年   25篇
  1984年   25篇
  1983年   26篇
  1982年   18篇
  1981年   15篇
  1980年   16篇
  1979年   22篇
  1978年   16篇
  1977年   15篇
  1976年   23篇
  1975年   16篇
  1972年   15篇
排序方式: 共有4406条查询结果,搜索用时 31 毫秒
81.
Titanium propoxide, titanium isopropoxide, and titanium (triethanolaminato) isopropoxide are proposed as high‐performance additives to overcome the oxygen inhibition effects in the free radical photopolymerization of a low‐viscosity monomer thin film, under air and upon a low‐intensity UV light activation. Indeed, when added to a Type I photoinitiator such as bis(2,4,6‐trimethylbenzoyl)‐phenylphosphine oxide (BAPO), noticeably higher conversions are achieved under air (48% vs. 30%). The in situ formation of Ti‐based nanoparticles is also observed. The photochemical properties of these types of Ti‐based compounds as well as their interaction with BAPO are investigated by steady‐state photolysis and electron spin resonance. Molecular orbital calculations give an interesting insight into the possible reactions. A chemical mechanism is also proposed.

  相似文献   

82.
83.
84.
85.

Purpose

Data on purpura fulminans (PF) in adult patients are scarce and mainly limited to meningococcal infections. Our aim has been to report the clinical features and outcomes of adult patients admitted in the intensive care unit (ICU) for an infectious PF, as well as the predictive factors for limb amputation and mortality.

Methods

A 17-year national multicenter retrospective cohort study in 55 ICUs in France from 2000 to 2016, including adult patients admitted for an infectious PF defined by a sudden and extensive purpura, together with the need for vasopressor support. Primary outcome variables included hospital mortality and amputation during the follow-up period (time between ICU admission and amputation, death or end of follow-up).

Results

Among the 306 included patients, 126 (41.2%; 95% CI 35.6–46.9) died and 180 (58.8%; 95% CI 53.3–64.3) survived during the follow-up period [13 (3–24) days], including 51/180 patients (28.3%, 95% CI 21.9–35.5) who eventually required limb amputations, with a median number of 3 (1–4) limbs amputated. The two predominantly identified microorganisms were Neisseria meningitidis (63.7%) and Streptococcus pneumoniae (21.9%). By multivariable Cox model, SAPS II [hazard-ratio (HR)?=?1.03 (1.02–1.04); p?<?0.001], lower leucocytes [HR 0.83 (0.69–0.99); p?=?0.034] and platelet counts [HR 0.77 (0.60–0.91); p?=?0.007], and arterial blood lactate levels [HR 2.71 (1.68–4.38); p?<?0.001] were independently associated with hospital death, while a neck stiffness [HR?0.51 (0.28–0.92); p?=?0.026] was a protective factor. Infection with Streptococcus pneumoniae [sub-hazard ratio 1.89 (1.06–3.38); p?=?0.032], together with arterial lactate levels and ICU admission temperature, was independently associated with amputation by a competing risks analysis.

Conclusion

Purpura fulminans carries a high mortality and morbidity. Pneumococcal PF leads to a higher risk of amputation.

Trials registration

NCT03216577.
  相似文献   
86.

Background

Septic shock is associated with hypovolemia resulting in organs failure and poor prognosis. The first step in hemodynamic resuscitation relies on early fluid expansion. In this study, we describe qualitative and quantitative fluid resuscitation of septic shock initially managed in a pre-hospital setting by a mobile intensive care unit.

Methods

Patients with septic shock who received pre-hospital medical care were retrospectively analysed. Qualitative and quantitative fluid resuscitation performed in the pre-hospital setting were analysed. Applying the "grey zone" concept, we define 3 categories of fluid expansion indexed on ideal body weight (IBW): >20ml/kg, 10-20ml/kg and ?<?10ml/kg. The relationship between the pre-specified categories and mortality at day 28 were analyzed.

Results

Ninety-five patients were included. The origin of sepsis was mainly pulmonary (68%). Mortality reached 34%. Pre-hospital fluid expansion was performed using serum saline (98%) with a mean of 1158±559ml. An inversed linear relationship between pre-specified categories and mortality was observed. Using logistic regression model, significant association with mortality remained for fluid expansion indexed on IBW: p=0.02, ORa [CI95] = 0.93 [0.89-0.98]. For fluid expansion indexed on IBW?<?10ml/kg, the OR [CI95] was 4.03 [1.78-9.41] (p=0.005) whereas for fluid expansion indexed on IBW?>?20ml/kg, the OR [CI95] was 0.30 [0.13-0.66] (p=0.01).

Discussion

Pre-hospital fluid resuscitation in septic shock is mainly performed using crystalloids with quantitative fluid expansion lower than recommended. Low pre-hospital fluid expansion was associated with increased mortality. Further prospective studies are needed to evaluate the impact of optimized early fluid expansion on mortality in the prehospital management of septic shock.  相似文献   
87.
Background. Compared to warfarin, the non-vitamin K antagonist oral anticoagulant rivaroxaban may have advantages in treating patients with venous thromboembolism, because injectable bridging therapy and routine laboratory monitoring are not required. The objective of this study was to compare the rate of hospitalization in patients treated with rivaroxaban after its introduction with what it would have been before the introduction of rivaroxaban. Methods. A retrospective claims analysis was conducted using the MarketScan Hospital Drug Database from January 2011 to December 2013. Adult patients with a primary diagnosis of deep vein thrombosis (DVT) treated with rivaroxaban or low-molecular-weight heparin (LMWH) bridged to warfarin during the first day of an evaluation at a hospital were identified. Based on propensity-score methods, historical LMWH/warfarin patients (i.e., patients who received LMWH/warfarin before the approval of rivaroxaban) were matched 4:1 to rivaroxaban patients, and the rates of hospitalization were compared. Results. All rivaroxaban-treated patients (n = 134) in the database were well matched with four historical LMWH/warfarin-treated patients (n = 536). Among the rivaroxaban cohort, 60% of the patients were admitted to the hospital, compared to 82% of the historical patients treated with LMWH/warfarin in the matched cohort. The difference was statistically significant and corresponded to a 27% reduction in hospital admissions (rate ratio [95% confidence interval]: 0.73 [0.62–0.84]). Hospital admission rates adjusted for time-trend analyses also led to similar results. Conclusion. The availability of rivaroxaban significantly reduced the hospitalization rate in patients with DVT treated with rivaroxaban compared to what it would have been if only LMWH/warfarin were available.  相似文献   
88.
89.

A substantial number of epileptic patients are resistant to the current medication thus necessitating the search for alternative therapies for intractable forms of the disease. Previous studies demonstrated the acute anticonvulsant properties of the methanol extract of the stem bark of Psychotria camptopus (MEPC) in rats. This study investigated the effects of MEPC on pentylenetetrazole-kindled Wistar rats. Kindling was induced by intraperitoneal injection of pentylenetetrazole (37.5 mg/kg) on every alternate day, 1 h after each daily oral pretreatment of rats (8?≤?n?≤?10) with MEPC (40, 80 and 120 mg/kg), vehicle or diazepam (3 mg/kg) for 43 days. The kindling development was monitored based on seizure episodes and severity. Rats’ brains were collected on day 43 for the determination of oxidative stress parameters. The histomorphological features and neuronal cell viability of the prefrontal cortex (PFC) and hippocampus were also assessed using H&E and Cresyl violet stains. Chronic administration of pentylenetetrazole time-dependently decreased the latency to myoclonic and generalized seizures, and increased seizure scores and the number of kindled rats. MEPC and diazepam significantly increased the latencies to myoclonic jerks and generalized tonic-clonic seizures. These substances also reduced seizure score and the number of rats with PTZ-kindling. MEPC improved glutathione status and decreased lipid peroxidation in the brains of kindled rats. MEPC also exhibited neuroprotection against pentylenetetrazole-induced hippocampal and PFC neuronal damages. These results suggest that P. camptopus has antiepileptogenic activity, which might be related to the augmentation of antioxidant and neuroprotective defense mechanisms, and further confirm its usefulness in the management of epilepsy.

  相似文献   
90.
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