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   6923篇
  免费   311篇
  国内免费   177篇
耳鼻咽喉   6篇
儿科学   238篇
妇产科学   174篇
基础医学   270篇
口腔科学   4篇
临床医学   1058篇
内科学   724篇
皮肤病学   27篇
神经病学   67篇
特种医学   451篇
外科学   2106篇
综合类   992篇
预防医学   396篇
眼科学   3篇
药学   478篇
  8篇
中国医学   295篇
肿瘤学   114篇
  2024年   15篇
  2023年   115篇
  2022年   234篇
  2021年   269篇
  2020年   222篇
  2019年   226篇
  2018年   210篇
  2017年   170篇
  2016年   187篇
  2015年   218篇
  2014年   552篇
  2013年   524篇
  2012年   456篇
  2011年   540篇
  2010年   422篇
  2009年   402篇
  2008年   411篇
  2007年   340篇
  2006年   295篇
  2005年   236篇
  2004年   205篇
  2003年   172篇
  2002年   125篇
  2001年   117篇
  2000年   86篇
  1999年   85篇
  1998年   67篇
  1997年   62篇
  1996年   47篇
  1995年   37篇
  1994年   35篇
  1993年   30篇
  1992年   27篇
  1991年   33篇
  1990年   19篇
  1989年   30篇
  1988年   17篇
  1987年   17篇
  1986年   14篇
  1985年   27篇
  1984年   15篇
  1983年   10篇
  1982年   15篇
  1981年   12篇
  1980年   12篇
  1979年   11篇
  1978年   13篇
  1977年   6篇
  1976年   10篇
  1975年   5篇
排序方式: 共有7411条查询结果,搜索用时 15 毫秒
11.
Objective The aim of this study was to identify risk factors and to describe epidemiological patterns for early—(EOB) and late—onset bacteremias (LOB) after trauma.Design A prospective study conducted on 141 consecutive trauma patients.Setting A general intensive care unit (ICU) of a university hospital.Patients All multiple trauma patients admitted to our general intensive care unit (ICU) from December 1990 to May 1992 were prospectively enrolled in the study. The following information was collected for each patient and recorded in a computer database: demography, severity of trauma according to the Abbreviated Injury Scale (AIS), severtity of trauma according to the Glasgow Coma Scale (GCS), presence of pneumothorax, pulmonary contusion, rib fractures, hemothorax, and abdominal trauma, use of mechanical ventilation, and placement of central venous catheters. Bacteremias were defined as EOB when onset occurred within 96 h after trauma, and as LOB when appearing after 96 h from trauma.Results Thirty-seven patients developed bacteremia during their ICU stay (26%): 11 (29.7%) EOB and 26 (70.3%) LOB. Gram-positive cocci were isolated more frequently in EOB than in LOB (x 2=4.1,P=0.04). The risk of EOB was significantly increased by the presence of pulmonary contusion [relative risk (RR) 15.0; confidence interval (CI) 1.99-113.25], pneumonia before the onset of bacteremia (RR 3.56; CI 1.17-10.69), AIS score greater than 32 and an abdominal injury score greater than 9 (RR 3.11; CI 1.02-9.49), while intravascular catheters and mechanical ventilation did not represent risk factors for EOB. LOB had a very different pattern and their risk was significantly increased by exposure to intravascular catheters (RR 4.96; CI 1.23-19.94) and to mechanical ventilation lasting more than 7 days (RR 3.6; CI 1.6-8.1).Conclusions Scoring with the AIS of the abdominal and thoracic trauma at admission to the ICU appears a useful tool for identifying trauma patients at increased risk of EOB. A rigorous policy of catheter placement and maintenance as a means of reducing late bacteremias in trauma patients is essential.  相似文献   
12.
The intraperitoneal mass most commonly encountered after blunt abdominal truama is a hematoma. However, one must also consider unusual bulky tumors that can have imaging characteristics similar to those of hematoma. The most typical of these neoplasms is lymphoma, but a desmoplastic small cell tumor also may be observed. The presentation and imaging findings of a desmoplastic small tumor are described.  相似文献   
13.
In a radiologic search for embolized leaflets of Edwards-Duromedics bileaflet valves in 2 patients, the embolized fragments were localized in the iliac vessels using computed tomography. Sonography was successful in one case and standard X-ray films of the abdomen were negative in both cases.In vitro investigations with Björk-Shiley and Edwards-Duromedics leaflets suggested that standard X-ray films of the abdomen and pelvis should be considered as the first investigational technique. If negative, computed tomography of the lower abdomen should be done.  相似文献   
14.
We hypothesized that walking at increased speed or increasing gradient might have different effects on chest wall kinematics and respiratory muscle power components, and contribute differently to respiratory effort sensation. We measured the volumes of chest wall compartments by optoelectronic plethysmography, esophageal, gastric and transdiaphragmatic (P di) pressures, and the sensation of the respiratory effort by a Borg scale in five normal subjects walking both at ascending gradient with constant speed (AG) and at ascending speed with constant gradient (AS). Chest wall kinematics, evaluated by displacement of chest wall compartments, did not show any significant difference between AS and AG. Muscle power, calculated as the product of mean flow and mean pressure, increased similarly, but its partitioning into pressure and velocity of shortening differed in the two modes. A greater increase in the pressure developed by the abdominal muscles (P abm) (4.06-fold), and in the velocity of shortening of both rib cage inspiratory muscles (v rcm,i) (2.01-fold) and the diaphragm (v di) (1.90-fold) was associated with a lower increase in the pressure developed by the rib cage inspiratory muscles (P rcm,i) (1.24-fold) and P di (0.99-fold) with AG. Instead, with AS, a lower increase in P abm (2.12-fold), v rcm,i (1.66-fold) and v di (1.54-fold) was associated with a greater increase in P rcm,i (1.56-fold) and P di (1.97-fold). A combination of P abm and v di during AG (Wald 2=23.19, P<0.0000), with the addition of P rcm,i during AS (Wald 2=29.46, P<0.0000), was the best predictor of Borg score. In conclusion, the general strategy adopted by respiratory centers during different walking modes does not differ in terms of ventilation, chest wall kinematics, and respiratory muscle power production, whereas it does in terms of partitioning of power into pressure and velocity of shortening, and respiratory muscle contribution to respiratory effort sensation. Combinations of different patterns of flow and pressure generation made the respiratory effort sensation similar during AS and AG modes.  相似文献   
15.
Among cases that had multiple renal arteries on one side, an inferior supernumerary renal artery was found in 24/270 cases (ca. 9%) on the right and in 19/270 cases (ca. 7%) on the left, together with the usual renal artery. We have noticed that there are correlations between their levels of origin from the aorta and their positional relation to the ureter and the inferior vena cava (IVC). An inferior supernumerary renal artery (InfRA) of lower origin passes in front of the IVC and behind the ureter. An InfRA of middle origin passes in front of both the IVC and the ureter. An InfRA of upper origin passes behind the IVC and in front of the ureter or renal pelvis. In addition there was a tendency for the lower origin type to have an ureteric branch, while the middle and upper origin types had a gonadal branch. These findings suggest that different derivations lead to the inferior supernumerary renal arteries.  相似文献   
16.
17.
18.
A rare case of splenic abscess occurring after blunt abdominal trauma in a previously healthy boy is reported. The diagnosis was made by ultrasonography. The patient recovered after splenectomy and drainage of subphrenic and intraperitoneal pus.  相似文献   
19.
目的:评估生物电子阻抗测定对腹部肿瘤病人手术前,后营养状况分析的有效性。方法;选择24例腹部肿瘤病人,用BIA分别测得术前和术后第5天的电阻和感应电阻,通过计算机RJL系统计算出身体细胞质量,脂肪和身体总水含量值,并与白蛋白和体重的变化相比较。结果;术后5天时,BCM的下降具有显著性差异,这与白蛋白,FAT,TBW和体重的下降是一致的。  相似文献   
20.
Umbilical hernia (UH) is a common condition in infants and young children, especially in those of Afro-Caribbean origin. Spontaneous closure occurs in a majority of cases before the age of 4 years unless the neck of the sac is greater than 2 cm in diameter. Complications are rare, and conservative management is therefore advised during this time. We present three cases of incarcerated UH in boys under 4 years old, all of whom presented with small-bowel obstruction. Interestingly, in two of them undigested vegetable matter in the small bowel appeared to have precipitated the obstruction. A survey of the literature suggests that the incidence of this complication is approximately 1:1,500 UHs. We conclude that the present policy of expectant management is safe for the vast majority of children, but parents and general practitioners should be aware of the small risk and early symptoms of incarceration. Accepted: 30 September 1997  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