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   1217篇
  免费   2篇
  国内免费   1篇
综合类   1篇
化学工业   3篇
矿业工程   2篇
能源动力   1篇
轻工业   2篇
无线电   3篇
一般工业技术   5篇
冶金工业   1203篇
  2016年   2篇
  2015年   1篇
  2011年   1篇
  2010年   1篇
  2006年   1篇
  2005年   1篇
  2003年   3篇
  2000年   1篇
  1999年   28篇
  1998年   322篇
  1997年   224篇
  1996年   154篇
  1995年   104篇
  1994年   60篇
  1993年   73篇
  1992年   6篇
  1991年   22篇
  1990年   7篇
  1989年   9篇
  1988年   5篇
  1987年   4篇
  1986年   3篇
  1985年   5篇
  1983年   3篇
  1982年   5篇
  1981年   11篇
  1980年   14篇
  1979年   1篇
  1978年   6篇
  1977年   48篇
  1976年   94篇
  1967年   1篇
排序方式: 共有1220条查询结果,搜索用时 10 毫秒
991.
It is recommended that a standard ration will be accompanied by "Unpit", natural casein concentrates, and "Glucosolan" vitaminized preparation to eliminate++ the disorders of trophological status of minimally wounded. There is a proposal to include the products of enteral nutrition for the ration of food supplies, because it would shorten the recovery time of minimally wounded, and, thus, accelerate their return to the ranks.  相似文献   
992.
In 111 patients who had anterior cruciate ligament reconstructions, postoperative radiographic measurements of anterior to posterior and medial to lateral location of the tibial tunnels were correlated with the final range of motion achieved. In the 25 patients with extension deficits of 10 degrees or more, placement of the tibial tunnel was more anterior (average, anterior 23% of the tibia) than in the remaining 86 patients with extension deficits of < 10 degrees (average, anterior 29% of tibia). This difference was statistically significant with P < 0.001. Logistic regression analysis revealed that the more anterior the placement of the tibial tunnel, the greater the loss of both flexion (P = 0.01) and extension (P = 0.002). In the 21 patients with full extension but flexion < 130 degrees, placement of the tibial tunnel tended to be more medial (average, medial 40% of the tibia) than in the 65 patients without flexion deficit (average, medial 45% of the tibia). We conclude that placement of the tibial tunnel in the "eccentric," anteromedial position may contribute to the development of flexion and extension deficits after anterior cruciate ligament reconstruction.  相似文献   
993.
Intraosseous anesthesia and associated anesthesia (a combination of intraosseous anesthesia and neuroleptic analgesia) were used in 120 traumatological patients. A comparative assessment of the anesthesia degree and the reaction of the organism to the operative agression was performed. The analysis of the results obtained shows advantages of the associated anesthesia over intraosseous anesthesia "per se". Fractionated infusion of phentanyl should be given in the dose 0,001 mg/kg of the body weight. The above variation of the associated anesthesia is supposed to be a perspective method in mass admission of patients.  相似文献   
994.
Multiple ventricular septal defects: how and when should they be repaired?   总被引:1,自引:0,他引:1  
BACKGROUND: Congenital heart lesions with multiple ventricular septal defects remain a surgical challenge. Traditional approaches often rely on either ventriculotomy for exposure or palliation with pulmonary artery banding. However, indications for repair versus palliation and for various approaches to surgical exposure are not clearly defined. METHODS: From July 1992 to January 1998, 45 patients with multiple (>/=2) ventricular septal defects (37 with associated lesions) underwent surgery. Median age was 86 days; all but 4 patients were infants. The mean number of defects was 3.7, and almost half of the patients had more than 3 defects. Apical muscular defects were present in 62% of patients. Thirty-one patients underwent primary complete repair through a right atriotomy or trans-semilunar valve approach (group 1), 8 had palliation (group 2), and 6 underwent complete repair after prior palliation elsewhere (group 3). No patient had a ventriculotomy. RESULTS: One early death occurred in a group 1 patient. Four patients who had had palliation (50%) underwent early reoperation for pulmonary artery band revision because of failure to thrive or band removal after spontaneous closure of the defects. At follow-up (median 22 months), there was 1 death in a group 2 patient (palliation) and 1 other group 2 patient required cardiac transplantation. The only late reoperation was for removal of the pulmonary artery band and closure of multiple apical defects in a group 2 (palliation) patient. No patients who underwent repair have hemodynamically significant residual defects. CONCLUSIONS: In our experience, palliation of multiple ventricular septal defects is associated with greater morbidity than primary repair. Multiple defects can almost always be repaired adequately in early infancy without ventriculotomy, although "Swiss-cheese" septum may be an indication for palliation.  相似文献   
995.
Severe attenuation of the B cell immune response in Msh2-deficient mice   总被引:3,自引:0,他引:3  
Recently, results obtained from mice with targeted inactivations of postreplication DNA mismatch repair (MMR) genes have been interpreted to demonstrate a direct role for MMR in antibody variable (V) gene hypermutation. Here we show that mice that do not express the MMR factor Msh2 have wide-ranging defects in antigen-driven B cell responses. These include lack of progression of the germinal center (GC) reaction associated with increased intra-GC apoptosis, severely diminished antigen-specific immunoglobulin G responses, and near absence of anamnestic responses. Mice heterozygous for the Msh2 deficiency display an "intermediate" phenotype in these regards, suggesting that normal levels of Msh2 expression are critical for the B cell response. Interpretation of the impact of an MMR deficiency on the mechanism of V gene somatic hypermutation could be easily confounded by these perturbations.  相似文献   
996.
Two experiments examined the viability of several explanations for why majority group individuals process persuasive messages from stigmatized sources more than those from nonstigmatized sources. In each study, majority group participants who either were high or low in prejudice or were high or low in ambivalence toward a stigmatized source's group were exposed to a persuasive communication attributed to a stigmatized (Black, Experiment 1; homosexual, Experiment 2) or nonstigmatized (White, Experiment 1; heterosexual, Experiment 2) source. In both studies, source stigmatization increased message scrutiny only among those who were low in prejudice toward the stigmatized group. This finding is most consistent with the view that people scrutinize messages from stigmatized sources in order to guard against possibly unfair reactions by themselves or others.  相似文献   
997.
OBJECTIVES: The study was done to determine the diagnostic accuracy of echocardiography alone in the preoperative diagnosis of children with major congenital heart defects undergoing primary complete repair. BACKGROUND: Although echocardiography is well established as the first-line imaging technique for the diagnosis of all forms of congenital heart disease, most institutions continue to perform cardiac catheterization prior to complete repair of more complex defects. METHODS: To determine the diagnostic accuracy of echocardiography alone and echocardiography plus catheterization, we reviewed the records of 503 children with major congenital heart defects who underwent primary complete repair at our institution between July 1992 and June 1997. We included children with transposition of the great arteries, tetralogy of Fallot, double-chamber right ventricle, interrupted aortic arch, aortic coarctation, atrioventricular septal defect, truncus arteriosus, aortopulmonary septal defect, and totally anomalous pulmonary venous return. We excluded children with less complex defects such as isolated shunt lesions, as well as those with the most complex defects that would require surgical palliation (e.g., functional univentricular heart). We defined major errors as those that increased the surgical risk and minor errors as those that did not. Errors in diagnosis were determined at surgery. RESULTS: Eighty-two percent of children (412 of 503) underwent surgery after preoperative diagnosis by echocardiography alone. There were 9 major (2%) and 10 minor errors in the echocardiography alone group and 7 major and 5 minor errors in the echocardiography plus catheterization group. The most common type of error was misidentification of coronary artery anatomy in patients with transposition of the great arteries. No error in either group resulted in surgical morbidity or mortality. CONCLUSIONS: This study suggests that echocardiography alone is an accurate tool for the preoperative diagnosis of major congenital heart defects in most children undergoing primary complete repair, and may obviate the need for routine diagnostic catheterization.  相似文献   
998.
This paper briefly reviews the components of, the clinical uses of, the techniques to place, and the complications related to implantable cardioverter-defibrillators (ICDs). Information useful in the specific identification of ICDs is presented. A series of recommendations for the autopsy examination or postmortem explantation of ICDs by the pathologist is given. Because of the serious risk of injury to the pathologist possible with postmortem discharges of ICDs which have not been deactivated, and because of the risk of device explosion if the ICD is incinerated, a number of cautionary notes are provided. A brief case with occurrence of accidental postmortem discharge of an active ICD is also presented.  相似文献   
999.
The aryl hydrocarbon receptor (AhR) shares a common PAS domain with a number of genes that exhibit a pronounced circadian rhythm. Therefore, this study examined the daily cycle of AhR and AhR nuclear translocator (Arnt) protein expression in multiple tissues of female Sprague-Dawley rats. Rats were euthanized at 4, 7, and 11 am and 4, 7, and 11 pm after which whole tissue homogenates were made from multiple tissues. Western blot analysis showed that the daily cycle of relative AhR protein expression exhibits a similar oscillation pattern in the liver, lungs, and thymus. The daily cycle of relative Arnt protein expression exhibits a similar oscillation pattern in the liver and lungs. The apparent daily cycle of AhR and Arnt protein expression in multiple tissues was not observed within the spleen. This preliminary report is the first study to suggest that the PAS proteins, AhR and Arnt, exhibit a daily oscillation pattern within multiple target tissues which may give insight into the tissue-specific toxic and biochemical responses mediated through this dimerization pair, as well as the physiological function of these proteins.  相似文献   
1000.
Besides the classic cholinergic and adrenergic mechanisms, the regulatory peptides involve in regulating the cardiac rhythm. The localization of the latter in neurons of intracardiac nervous system as well as the possibility of releasing the regulatory peptides, individually or in combination with the classic mediators, during extracardiac nerves is found. The regulatory peptides are capable of affecting the heart autonomy directly or in a mediated way via modulation of the vegetative effects. The paper contains data on the cardiotropic activity of various peptides and direction of their effects relating to parasympathetic control a cardiac rhythm. There is a suggestion concerning an existence of different ways of realization of peptidergic vagotropic effect that presupposes not only variation of severity of parasympathetic chronotropic effect but also a change in its functional organization.  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