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   479篇
  免费   96篇
  国内免费   1篇
儿科学   78篇
妇产科学   9篇
基础医学   114篇
口腔科学   2篇
临床医学   55篇
内科学   129篇
皮肤病学   3篇
神经病学   46篇
特种医学   12篇
外科学   66篇
综合类   15篇
一般理论   2篇
预防医学   27篇
眼科学   5篇
药学   4篇
肿瘤学   9篇
  2017年   5篇
  2013年   6篇
  2012年   8篇
  2011年   12篇
  2010年   4篇
  2009年   6篇
  2008年   11篇
  2007年   12篇
  2006年   10篇
  2005年   13篇
  2004年   13篇
  2003年   9篇
  2002年   11篇
  2001年   6篇
  2000年   12篇
  1999年   7篇
  1998年   4篇
  1996年   5篇
  1995年   5篇
  1994年   4篇
  1993年   7篇
  1992年   16篇
  1991年   22篇
  1990年   33篇
  1989年   26篇
  1988年   26篇
  1987年   26篇
  1986年   31篇
  1985年   18篇
  1984年   13篇
  1983年   8篇
  1982年   6篇
  1981年   8篇
  1980年   10篇
  1979年   10篇
  1978年   8篇
  1977年   6篇
  1976年   13篇
  1975年   10篇
  1974年   17篇
  1973年   18篇
  1972年   11篇
  1971年   8篇
  1970年   10篇
  1969年   8篇
  1968年   3篇
  1966年   3篇
  1965年   5篇
  1931年   3篇
  1841年   4篇
排序方式: 共有576条查询结果,搜索用时 15 毫秒
1.
The percentage uptake of [123I]metaiodobenzylguanidine (MIBG) by tumors of the paraganglion system is compared with the number of neurosecretory granules (assessed by both light and electron microscopy) in the subsequently resected tumors in six patients. Iodine-123 MIBG was injected intravenously; the tumor uptake of [123I]MIBG varied between 0.001% and 0.14% of the injected dose per gram of tumor tissue at 22 hr. The number of neurosecretory granules in tissue sections was scored on a scale of I-III. A direct proportional correlation was found between the percentage uptake of [123I]MIBG by the tumor and the number of neurosecretory granules in the tissue sections but not with plasma or urinary catecholamines. This technique for imaging reflects the storage status of the tumor better than plasma and urinary catecholamine measurements.  相似文献   
2.
M A Levison  D D Thomas  R G Wiencek  R F Wilson 《The Journal of trauma》1990,30(3):247-51; discussion 251-3
The records of 239 patients surviving more than 24 hours with full-thickness intraperitoneal colonic injuries over a 7-year period were reviewed. During the first 3 years, 29% (31/106) of the patients were managed by primary repair without colostomy. In the next 4 years, almost twice as many patients, 56% (75/133), with similar colonic trauma were treated without fecal diversion (p less than 0.05). Although there was no difference in the mean Trauma Score in the patients with primary repair in the two time periods, the Injury Severity Score (mean +/- sd) in the patients without colostomy in the later periods was significantly higher (17.8 +/- 2.1 vs. 20.2 +/- 5.1) (p less than 0.001). No patient suffered because of the increased incidence of primary repairs. These patients had five abdominal abscesses and only one leak, whereas the patients with colostomy had 15 intraperitoneal abscesses. Because of the safety when primary repair is performed, more liberal use of primary colonic repair following penetrating trauma is warranted.  相似文献   
3.
This study presents a clinical validation of postoperative measurements of acetabular cup alignment following total hip arthroplasty (THA). The methodology was based on concurrent anatomic three-dimensional (3D) measurements of both the acetabular cup alignment and pelvic orientation, using an original CT/X-ray matching algorithm named Xalign. The subjects were 19 patients who had undergone bilateral THA using CT-based surgical navigation. All patients had postoperative pelvic CT scans and multiple antero-posterior (AP) pelvic X-rays. Using a proprietary software algorithm, the X-rays included in the study were matched with the corresponding postoperative CT scans. The goal of this method was to allow 3D anatomic pelvic and acetabular measurements on two-dimensional AP X-rays. The postoperative cup abduction, version and pelvic flexion angles were determined in three different ways: using CT images directly, applying the Xalign method, and finally by performing conventional (abduction only) measurements on AP pelvic X-rays. The cup orientation measured on CT images was taken as the ground truth. The Xalign measurement errors were defined as the difference between the CT cup values and those obtained by applying the matching method. The mean cup abduction error was 0.85 degrees +/- 1.3 degrees (+/- standard deviation) and the mean version error was 0.01 degrees +/- 1.99 degrees . Conventionally measured cup abduction ranged from 44 degrees to 62 degrees and correlated significantly (p = 0.001, r = -0.5) with pelvic flexion angle, proving the linear negative correlation between pelvic flexion and the error in conventional radiographic cup measurements. The Xalign method offered reasonable accuracy for cup orientation, and allowed cup and pelvic 3D anatomic measurements at different times.  相似文献   
4.
We have compared lung function in 3 subjects with no alpha 1-antitrypsin (alpha 1-protease inhibitor) (null homozygotes) with subjects having the typical deficiency, PIZZ. We identified a 31-yr-old woman, presenting with severe obstructive lung disease, who had no detectable plasma alpha 1-antitrypsin, indicating homozygosity for a "null" (or PI*QO) allele of alpha 1-antitrypsin. Two of her sisters have a similar deficiency, one with an onset of symptoms at 17 yr of age. Because of the likelihood that there are a number of different PI*QO alleles, the type in this family has been named null Mattawa (QOmattawa). All 3 homozygotes have shown a marked deterioration of lung function over a 7-yr period of follow-up. In contrast, lung function tests of 6 age-matched nonsmoking subjects with alpha 1-antitrypsin deficiency, PI type ZZ, showed no abnormalities of lung function. The 15 to 20% of the normal plasma concentration of alpha 1-antitrypsin associated with the PI*Z allele appears to provide some protection to the lung in comparison with a complete deficiency state.  相似文献   
5.
6.
A study was performed to compare the efficacy and safety of two therapeutic regimens for the treatment of children presenting to the emergency department with acute asthma. A regimen of inhaled salbutamol alone was compared to inhaled salbutamol combined with ipratropium bromide. Twenty-five children ranging in age from 5 to 15 years were enrolled in the study. Children with FEV1 less than or equal to 55% predicted were eligible to participate in the study. Subjects were randomized in a double-blind fashion into one of two treatment groups. Both groups received an initial dose of salbutamol by nebulizer of 150 micrograms/kg (0.03 cc/kg), followed by six consecutive doses of 50 micrograms/kg (0.01 cc/kg) at 20-minute intervals. In one group of subjects, 250 micrograms (1.0 ml) of ipratropium bromide respirator solution was added to the salbutamol administered at the time of the initial inhalation, and at 40 and 80 minutes, whereas the remaining subjects received a placebo with salbutamol at those times. Formal one-way statistical ANOVA with change in percent predicted FEV1 as a response variable confirmed there was a statistically significant difference at all time points caused by drug regimen during the 150-minute observation period. There was no significant difference in side effects reported in the two groups. Significant additional bronchodilation achieved with salbutamol and ipratropium bromide together indicates that there is likely a substantial cholinergic element to the bronchospasm observed in acute exacerbations of asthma in the pediatric age group.  相似文献   
7.
The findings of a survey on the use of immunohistochemistry in district general hospitals in England and Wales are reported. Immunohistochemistry is used in most district hospitals, contributes to the accuracy and objectivity of some histopathological diagnoses, and is considered to be generally useful though not without drawbacks. Its expansion is being hindered by lack of funds for reagents and staff. In a few regions attempts are being made to rationalise expenditure and coordinate development of the service. We believe that if this can be done at a regional or national level then the relatively small cost entailed will be justified by a resulting improvement in the quality of patient care.  相似文献   
8.
The bcl-2 proto-oncogene, which inhibits programmed cell death (apoptosis), has recently been found to be cyclically expressed in human endometrium. In order to investigate its role in endometrial hyperlasia and neoplasia, bcl-2 expression was studied in 25 cases of endometrial carcinoma and 20 cases of endometrial hyperplasia (eight simple, two complex, and ten atypical hyperplasias). Uniform intense cytoplasmic bcl-2 expression was found in all cases of non-atypical hyperplasia, and less strong positivity in eight out of ten cases of atypical hyperplasia. In well-differentiated carcinomas, nine out of ten showed weak to moderate bcl-2 expression, whereas six out of seven poorly differentiated carcinomas were bcl-2-negative. Moderately differentiated tumours were an intermediate group, with six out of eight being positive. Widespread localization of bcl-2 protein to the chromosomes of dividing cells was also demonstrated, regardless of cytoplasmic bcl-2 expression, with rare staining of interphase nuclei. Our findings suggest a role for bcl-2 in the natural history of endometrial neoplasia and studies are needed to determine its usefulness as a prognostic marker. The finding of bcl-2 localization to chromosomes has important implications for its mode and site of action.  相似文献   
9.
The challenge for patient, family, and healthcare professionals alike is to separate the disease's insidiousness from the potential the patient and family have to enjoy life within the patient's abbreviated life span. We must emphasize that most patients with CF and their families do make a successful psychological adjustment. Simultaneously, parents must fulfill the varied physical and psychological needs of the child. A young adult patient with CF summarizes the patient's task: "Projecting a life goal, living it, having the goal altered by luck and by fate, accomplishing that goal, and then reflecting on what has been done. That is life. That is a life compressed for us; CF is myopic. We cannot look through the long vista of life. That is disappointing, frustrating, and cursed at. We can live now. We can do the best we can. Set goals that fit on our playing field and accomplish them." An emotionally adjusted family makes the patient's task possible. Achieving the goal of adequate adjustment also depends on the physician's having the medical expertise to manage this complex multisystem illness and the ability to make the medical knowledge comprehensible for patient and family.  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