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   2009篇
  免费   120篇
  国内免费   12篇
耳鼻咽喉   14篇
儿科学   76篇
妇产科学   51篇
基础医学   269篇
口腔科学   18篇
临床医学   181篇
内科学   409篇
皮肤病学   64篇
神经病学   291篇
特种医学   86篇
外科学   235篇
综合类   12篇
预防医学   156篇
眼科学   42篇
药学   104篇
中国医学   1篇
肿瘤学   132篇
  2022年   10篇
  2021年   11篇
  2020年   13篇
  2019年   19篇
  2018年   38篇
  2017年   22篇
  2016年   33篇
  2015年   33篇
  2014年   51篇
  2013年   58篇
  2012年   86篇
  2011年   95篇
  2010年   59篇
  2009年   60篇
  2008年   88篇
  2007年   81篇
  2006年   71篇
  2005年   79篇
  2004年   99篇
  2003年   63篇
  2002年   76篇
  2001年   74篇
  2000年   74篇
  1999年   70篇
  1998年   39篇
  1997年   35篇
  1996年   29篇
  1995年   27篇
  1994年   21篇
  1993年   24篇
  1992年   33篇
  1991年   21篇
  1990年   29篇
  1989年   47篇
  1988年   30篇
  1987年   36篇
  1986年   21篇
  1985年   30篇
  1984年   27篇
  1983年   21篇
  1982年   15篇
  1981年   16篇
  1979年   25篇
  1978年   10篇
  1977年   27篇
  1975年   16篇
  1971年   8篇
  1966年   9篇
  1954年   8篇
  1932年   10篇
排序方式: 共有2141条查询结果,搜索用时 250 毫秒
1.
2.
Multiple trauma is often associated with blunt thoracic injuries. Especially lung contusion can result in respiratory insufficiency and therefore a higher mortality rate. In our prospective study comparing 8 multiple trauma patients with and without associated lung contusion, we found that respiratory function was already significantly disturbed (decrease of paO2/FiO2 and increase of AaDO2, a rise in extravascular lung water (EVLW) both early after trauma and also with a second peak following the 4th day. This group (LK) developed significantly more cases of respiratory distress (ARDS). The disturbance of respiratory function seen initially was interpreted as a consequence of the direct mechanical impact, leading to the formation of interstitial fluid and hematoma. The frequent development of ARDS in the LK-group probably results from a pronounced activation of cellular and humoral mechanisms and therefore an enforced injury of the pulmonary capillary bed. A significant increase of pulmonary infections or the development of sepsis was not seen in the LK-group and is probably not responsible for the higher ARDS-rate in this group.  相似文献   
3.
To determine the muscarinic receptor subtype mediating guinea pig ileal mucosal electrolyte secretion, we compared the potencies (Kb) of selective M1 (pirenzepine) (PZ), M2 (AF-DX 116, methoctramine), and M3 [4-diphenylacetoxy-N-methylpiperidine methiodide (4-DAMP), hexahydrosiladifenidol (HHSiD)] antagonists as inhibitors of carbachol-induced reductions in guinea pig atrial heart rate and ileal longitudinal muscle contractions, responses mediated by M2 and M3 receptors, respectively. Pretreatment with all five muscarinic antagonists shifted the carbachol concentration-response curve to the right, in a manner suggesting competitive antagonism. The following affinity profiles (Kb, nM) were obtained for: 1) ileal mucosa: 4-DAMP (2.7) greater than HHSiD (23.0) greater than PZ (110) greater than or equal to methoctramine (395) greater than AF-DX 116 (784); 2) atrial heart rate: 4-DAMP (9.5) congruent to methoctramine (11) greater than AF-DX 116 (63) greater than HHSiD (222) greater than PZ (256); and 3) ileal longitudinal muscle: 4-DAMP (3.1) greater than HHSiD (21) greater than PZ (143) greater than methoctramine (388) greater than or equal to AF-DX 116 (482). The selectivity profiles of these antagonists suggest that muscarinic receptors in the ileal mucosa more closely resemble those in the ileal muscle (M3) than those in atrial muscle (M2). Moreover, M1-muscarinic receptors appear to be relatively unimportant in mediating the effects of carbachol on short circuit current (ISC). Carbachol-induced increases in ISC were also unaffected by pretreatment with 0.5 microM tetrodotoxin, suggesting that electrolyte transport in the guinea pig ileal mucosa may be mediated, in part, by postsynaptic M3-muscarinic receptors on the enterocytes.  相似文献   
4.
Severe injuries in patients of all ages and injuries in elderly multi-morbid subjects are a relevant medical and economic challenge. Optimal care of the polytraumatized patient can be best delivered by physicians specializing both in causal treatment of the injury or underlying disease and in intensive care. For care of critically ill injured patients, trauma surgeons with a certified specialty in intensive care medicine appear best suited. Of course, directing a surgical or trauma intensive care unit has to be full-time. Specialization of trauma surgeons (e.g., in the USA) has resulted in a considerable improvement in outcomes at least partly related to specialized trauma intensive care. Further improvement of trauma care relies on competent and innovative research not only in the fields of general intensive care, e.g., ventilation, but particularly in the complex aspects of the causality of the traumatic disease. An integrative view of the pathobiochemical, pathophysiological, and immunopathological sequelae of severe trauma under consideration of the various surgical and therapeutic strategies is the actual focus of research in surgical critical care medicine. Organ dysfunctions have to be modulated as they develop. Surgeons and trauma surgeons lead worldwide in this field of research. Obviously, competent research in polytrauma care requires competence in polytrauma intensive care.  相似文献   
5.
In trauma surgery there is a particularly high proportion of patients in the age group most at risk of infection with AIDS. The result of an epidemiological study in our patients (HIV screening of all patients scheduled for surgery at a trauma center over 18 months) showed a prevalence of 0.1%. Specific therapeutic strategies must be developed to deal with the weakened immunity of HIV-infected patients. Fracture treatment in HIV-infected hemophiliacs is a special problem. Homogenous bone transplantation is described with reference to HIV. The particular danger of injury in trauma surgery is also investigated. The chain of infection is illustrated and used to demonstrate the precautions that can be taken against nosocomial HIV infections. Following infection with fluids containing HIV, specific measures must be taken. The legal aspects of HIV-antibody testing in the Federal Republic of Germany are elucidated. Finally, the problems of general preoperative HIV-antibody testing are discussed.  相似文献   
6.
7.
1. Phospholipase A2 (PLA2) cleaves phospholipids to produce a lyso-phospholipid and free fatty acid and, in view of the biological activity of the products, PLA2 may play a role in many disease states. Lyso-phospholipids and free arachidonic acid increase in ischaemic myocardium, indicating that ischaemia activates the enzyme. 2. Plasma PLA2 activity was measured in patients with acute myocardial infarction, based on the release of labelled arachidonic acid from Escherichia coli cell membrane. Fourteen males (peak serum creatine phosphokinase (CK) above twice upper normal) were studied on day 1 (within 6 h of chest pain onset), days 2-4, and days 6-9. Normal age matched males (n = 13) were also studied. 3. Plasma PLA2 in patients with uncomplicated myocardial infarction (n = 12) was, initially, 1.14 +/- 0.10 (s.e.m.) nmol/min per mL plasma, similar to that in the normal group (1.52 +/- 0.14). On days 2-4, PLA2 activity increased to 1.94 +/- 0.18 (P less than 0.001) and this activity was correlated with the earlier peak CK level (P less than 0.02). On days 6-9, PLA2 activity was 1.49 +/- 0.13 while in two patients who developed complications and underwent open-heart surgery between the last two measurements, there were further increases to 4.22 and 4.04 nmol/min per mL. 4. The increase in plasma PLA2 in uncomplicated myocardial infarction is likely to be due to release from the damaged myocardium; whether it contributes to pathophysiology is uncertain.  相似文献   
8.
Eleven children with cerebral palsy were studied after shelf acetabular augmentation for progressive hip subluxation. Evaluation was based on computed tomography (CT) scans and radiographic measurements. We noted significant improvement in subluxation as measured by migration percentage, without increased subluxation of the nonoperated hip. Preoperatively, our patients had anterior acetabular deficiencies and increased acetabular anteversion, but no posterior deficiency by CT scanning. The acetabular shelves were positioned relatively more anteriorly than posteriorly. This appears to be appropriate owing to the relative anterior deficiencies of the acetabuli in our patients.  相似文献   
9.
Two variant cells lines resistant to the nitrosourea derivative ACNU ((1-4-amino-2-methyl-5-pyrimidinyl)-methyl-3-(2-chloroethyl)-3-nitrosourea hydrochloride), namely C6/ACNU and 9L/ACNU, were selected in vivo from rat brain tumors. Stable resistance to ACNU proved to be a characteristic of these cell lines, whether they were grown in vivo or in vitro. These cell lines exhibited a different pattern of cross-resistance to a wide range of chemotherapeutic agents with dissimilar chemical structures and mechanisms of action as compared with that of other ACNU-resistant cell lines established in vitro. Distinct cross-resistance was observed in both the C6/ACNU and 9L/ACNU cell lines to chloroethyl-nitrosoureas such as BCNU (carmustine), CCNU (lomustine), and methyl CCNU and, additionally, to vincristine, vinblastine, Adriamycin (doxorubicin), and arabinosylcytosine, but not to bleomycin, methotrexate, cis-platinum, and 5-fluorouracil. This might point to a multifactorial mechanism of drug resistance in ACNU-resistant cell lines derived from rat C6 and 9L brain tumor cells.  相似文献   
10.
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