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   214篇
  免费   10篇
  国内免费   4篇
儿科学   24篇
妇产科学   2篇
基础医学   15篇
口腔科学   2篇
临床医学   15篇
内科学   46篇
皮肤病学   4篇
神经病学   5篇
特种医学   81篇
外科学   13篇
综合类   3篇
预防医学   2篇
药学   9篇
肿瘤学   7篇
  2022年   1篇
  2021年   1篇
  2020年   2篇
  2019年   7篇
  2018年   1篇
  2017年   1篇
  2016年   3篇
  2015年   1篇
  2014年   2篇
  2013年   5篇
  2012年   1篇
  2011年   1篇
  2010年   5篇
  2009年   10篇
  2007年   5篇
  2006年   3篇
  2004年   1篇
  2003年   1篇
  2002年   1篇
  2001年   3篇
  2000年   2篇
  1999年   2篇
  1998年   15篇
  1997年   13篇
  1996年   16篇
  1995年   5篇
  1994年   9篇
  1993年   11篇
  1992年   1篇
  1991年   1篇
  1990年   5篇
  1989年   12篇
  1988年   10篇
  1987年   9篇
  1986年   9篇
  1985年   11篇
  1984年   3篇
  1983年   6篇
  1982年   9篇
  1981年   1篇
  1980年   4篇
  1979年   4篇
  1978年   6篇
  1977年   4篇
  1976年   2篇
  1975年   3篇
排序方式: 共有228条查询结果,搜索用时 0 毫秒
41.
This paper describes rates and causes of injury deaths among community members in three districts of the United Republic of Tanzania. A population-based study was carried out in two rural districts and one urban area in Tanzania. Deaths occurring in the study areas were monitored prospectively during a period of six years. Censuses were conducted annually in the rural areas and biannually in the urban area to determine the denominator populations. Cause-specific death rates and Years of Life Lost (YLL) due to injury were calculated for the three study areas. During a 6 year period (1992-1998), 5047 deaths were recorded in Dar es Salaam, 9339 in Hai District and 11 155 in Morogoro Rural District. Among all ages, deaths due to injuries accounted for 5% of all deaths in Dar es Salaam, 8% in Hai and 5% in Morogoro. The age-standardised injury death rates among men were approximately three times higher than among women in all study areas. Transport accidents were the commonest cause of mortality in all injury-related deaths in the three project areas, except for females in Hai District, where it ranked second after intentional self-harm. We conclude that injury deaths impose a considerable burden in Tanzania. Strategies should be strengthened in the prevention and control of avoidable premature deaths due to injuries.  相似文献   
42.
Kleiner  B; Filly  RA; Mack  L; Callen  PW 《Radiology》1986,161(1):27-29
To evaluate multicystic dysplastic kidney (MDK) and associated contralateral renal abnormalities in the fetal population, 27 cases detected and followed in utero were reviewed retrospectively. The sonographic assessment included estimation of amniotic fluid volume and interval growth, evaluation for non-genitourinary anomalies, and postnatal follow-up study. Contralateral renal anomalies were detected in 41% of the fetuses and included obstruction of the ureteropelvic junction, renal agenesis, renal hypoplasia, and bilateral MDK. The incidences of these malformations were compared with results of earlier studies of MDK in the pediatric and adult populations. Lethal anomalies, such as bilateral MDK and MDK associated with contralateral agenesis, are common (19% and 11%, respectively) in the fetal population; obstruction of the contralateral ureteropelvic junction, a nonlethal anomaly, was seen less commonly (7%). Perinatal death from lethal abnormalities may spuriously raise the incidence of nonlethal contralateral abnormalities in the pediatric and adult populations. Contralateral mild fetal pyelectasis, found in 15% of fetuses with MDK, was not clinically significant.  相似文献   
43.
Resolving duodenal-jejunal hematoma in abused children   总被引:1,自引:0,他引:1  
Kleinman  PK; Brill  PW; Winchester  P 《Radiology》1986,160(3):747-750
Acute intramural duodenal-jejunal hematoma is a classical finding in the battered child syndrome. The radiographic findings of a large obstructing intramural mass associated with the "coiled-spring" appearance generally raise the question of child abuse in any patient without appropriate accidental injury. In this study the radiologic features of resolving duodenal-jejunal hematoma are detailed in five abused children. The results show that the coiled-spring appearance is an acute phenomenon associated with a well-localized intramural hematoma. In the resolving phase, localized mural masses in the lateral aspect of the descending duodenum and fold thickening are indications of prior intramural hemorrhage. When these radiologic features are encountered in a child with nonspecific abdominal complaints, child abuse should be suspected. Furthermore, in patients with suspected occult trauma, resolution of abdominal symptoms should not deter the radiologist from performing an upper gastrointestinal tract series, which may provide evidence of child abuse.  相似文献   
44.
Plasma thyroid stimulating hormone (TSH) concentrations obtained during the first four years of treatment in 418 children with congenital hypothyroidism, identified by neonatal screening, were examined in relation to paired measurements of plasma thyroxine (n = 1945), free thyroxine (n = 836), triiodothyronine (n = 480), and free triiodothyronine (n = 231), and estimated daily dose of thyroxine at the time of blood sampling. Overall, plasma TSH was above 7 mU/l in 1280 out of 2960 samples (43%); the percentage was not related to severity of hypothyroidism at diagnosis. Mean values for thyroxine and free thyroxine, and to a lesser extent free triiodothyronine, were consistently lower in samples with TSH concentrations over 7 mU/l and this was the case in patients with either severe or less severe hypothyroidism. Raised TSH concentrations were also associated with lower mean doses of thyroxine (micrograms/kg/day) but here the mean doses of thyroxine in children with severe hypothyroidism were higher than in the children with less severe hypothyroidism. The mean dose of thyroxine associated with low/normal TSH values was highest in the first 6 months and fell progressively. Thyroxine dose was significantly related to thyroxine and free thyroxine concentrations but not to triiodothyronine and free triiodothyronine and the latter appeared to be of limited value as measures of plasma thyroid hormone status during treatment.  相似文献   
45.
Ishii  H; Salem  HH; Bell  CE; Laposata  EA; Majerus  PW 《Blood》1986,67(2):362-365
Protein C activation by thrombin is significantly accelerated by the endothelial cell cofactor, thrombomodulin. In this study, we have developed a radioimmunoassay for thrombomodulin and have measured the cofactor content in several human tissues. The assay method detects as little as 2 ng of thrombomodulin. The highest thrombomodulin content was found in lung and placenta, but the antigen was also detected in spleen, pancreas, liver, kidney, skin, heart, and aorta. Unexpectedly, thrombomodulin was absent from brain. Extracts from cerebral cortex, cerebellum, centrum semiovale, midbrain, basal ganglia, pons, and medulla were devoid of thrombomodulin. In contrast, thrombomodulin antigen is present in extracerebral intracranial vessels, including basilar and internal carotid arteries and choroid plexus, as well as in endothelium of the pia-arachnoid.  相似文献   
46.

Background

Intraoperative mortality is now rare, but death within 30 days of surgery remains surprisingly common. Perioperative myocardial infarction is associated with a remarkably high mortality. There are strong associations between hypotension and myocardial injury, myocardial infarction, renal injury, and death. Perioperative arterial blood pressure management was thus the basis of a Perioperative Quality Initiative consensus-building conference held in London in July 2017.

Methods

The meeting featured a modified Delphi process in which groups addressed various aspects of perioperative arterial pressure.

Results

Three consensus statements on intraoperative blood pressure were established. 1) Intraoperative mean arterial pressures below 60–70 mm Hg are associated with myocardial injury, acute kidney injury, and death. Injury is a function of hypotension severity and duration. 2) For adult non-cardiac surgical patients, there is insufficient evidence to recommend a general upper limit of arterial pressure at which therapy should be initiated, although pressures above 160 mm Hg have been associated with myocardial injury and infarction. 3) During cardiac surgery, intraoperative systolic arterial pressure above 140 mm Hg is associated with increased 30 day mortality. Injury is a function of arterial pressure severity and duration.

Conclusions

There is increasing evidence that even brief durations of systolic arterial pressure <100 mm Hg and mean arterial pressure <60–70 mm Hg are harmful during non-cardiac surgery.  相似文献   
47.
Magnetic resonance (MR) imaging has given mixed results in the detection of renal masses. To identify the reasons for this and to determine the optimal pulse sequences for evaluating renal tumors, the authors imaged 12 primary renal tumors in vivo and 17 in vitro at 0.35 T. Histopathologic findings for each specimen were closely correlated with the MR images. Four of seven solid tumors imaged in vivo were isointense with surrounding normal renal parenchyma at all pulse sequences. The other three tumors were hyperintense in vivo at T2-weighted sequences. At heavily T2-weighted sequences eight solid tumors were hyperintense in vitro and four were hypointense. There was no correlation between signal intensity and specific tissue type or histologic pattern for solid tumors. The five cystic tumors were well seen both in vivo and in vitro on T2-weighted images. However, the signal intensity of the cyst fluid was an unreliable indicator of benignancy. SE MR imaging at 0.35 T has significant limitations in the detection of solid renal masses.  相似文献   
48.
Schick  PK; Tuszynski  GP; Vander Voort  PW 《Blood》1983,61(1):163-166
The lipid composition of platelet cytoskeletons was analyzed. Triton X- 100 (0.5%) was used to prepare cytoskeletons from thrombin-treated platelets. The lipid/protein ratio of platelet cytoskeletons was 0.260 and the phospholipid/protein ratio was 0.177, which were comparable to the ratios present in platelets. However, there was a selective enrichment of platelet lipids in platelet cytoskeletons. Only 2 of the 5 major platelet phospholipids were detected. About 14% platelet sphingomyelin and 2% platelet phosphatidylcholine were present in platelet cytoskeletons. Only 1 of the 4 platelet neutral glycolipids, trihexosyl ceramide, was detected and was about 7% of that in intact platelets. Two percent of platelet hematoside, the predominant ganglioside in platelets, was found in cytoskeletons. Six percent of platelet cholesterol was present in platelet cytoskeletons, while no other neutral lipid could be detected. The study demonstrates that the lipid/protein ratio of platelet cytoskeletons is similar to that in platelets, but the composition of cytoskeleton lipids is specific and distinctly different from that in platelets. The selective glycolipid and phospholipid composition of cytoskeletons may be important for cytoskeleton and platelet function.  相似文献   
49.
Detecting fetomaternal hemorrhage: a comparison of five methods   总被引:3,自引:0,他引:3  
Appropriate postpartum administration of Rh immune globulin relies on sensitive detection and accurate quantitation of fetomaternal hemorrhage (FMH). Recently, the microscopic Du test (micro Du) enhanced with polyethylene glycol (PEG Du) and flow cytometry (FC) have been advocated for this purpose. Three qualitative methods (micro Du, rosette test, and PEG Du) and two quantitative methods (acid elution and FC) for assessing FMH were evaluated with particular attention given to PEG Du and FC. In vitro studies comprised 10 series of dilutions of D+ cord cells in D- adult cells to yield D+ cell concentrations of 0.06, 0.12, 0.25, 0.50, 0.75, 1.0, and 2.0 percent. Additionally, 26 postpartum samples were tested. Of the qualitative techniques, the micro Du test was the least sensitive with 20 percent false-negative results occurring at 0.5 percent fetal cells. The PEG Du test was only slightly more sensitive and offered no clinical advantage. The rosette test was the most sensitive, consistently detecting fetal cells at concentrations of 0.25 percent or greater. FC and acid elution showed similar results, with good correlation obtained between measured and expected quantities of fetal cells (r = 0.99 and 0.96, respectively). One of 26 postpartum samples was positive by all screening techniques; acid elution and FC detected 0.3-percent concentrations of fetal cells and 0.17-percent concentrations of D+ cells, respectively. Although acid elution is a more commonly used method for quantitating FMH, FC offers an acceptable alternative that is capable of analyzing large numbers of cells with objectivity and reproducibility.  相似文献   
50.
A postulated role of the contact system in anaphylactic reactions to insect stings was investigated. During prospective, in-hospital sting challenge, we collected serial blood samples from five normal volunteers and 16 patients with a history of insect-sting anaphylaxis. Activation of the contact system was assessed by measuring plasma levels of factor XIIa-C1-inhibitor and kallikrein-C1-inhibitor complexes as well as those of cleaved high molecular weight kininogen (HK). In addition, antigenic levels of (pre)kallikrein, factor XII, and HK were measured. No significant changes in contact system parameters were observed in any of the five volunteers or the four patients who did not develop an anaphylactic reaction after sting challenge. In contrast, significant changes in contact system parameters occurred in 7 of the 12 patients with anaphylactic symptoms after challenge. Peak levels of either C1-inhibitor complex were found 5 minutes after the onset of anaphylactic symptoms. The increase in C1-inhibitor was most pronounced in the 4 patients with angioedema, 2 of which also developed shock. However, activation of HK was observed in all four patients with angioedema, the two patients with shock but no angioedema, as well as in 1 of the remaining 6 patients with anaphylactic symptoms other than angioedema or shock. Thus, activation products of the contact system may be involved in the pathogenesis of angioedema and shock in insect- sting anaphylaxis.  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