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   743篇
  免费   45篇
  国内免费   10篇
耳鼻咽喉   12篇
儿科学   30篇
妇产科学   8篇
基础医学   65篇
口腔科学   12篇
临床医学   69篇
内科学   148篇
皮肤病学   13篇
神经病学   32篇
特种医学   160篇
外科学   54篇
综合类   31篇
预防医学   24篇
眼科学   4篇
药学   63篇
中国医学   6篇
肿瘤学   67篇
  2023年   6篇
  2022年   2篇
  2021年   8篇
  2020年   3篇
  2019年   9篇
  2018年   11篇
  2017年   3篇
  2016年   25篇
  2015年   54篇
  2014年   22篇
  2013年   23篇
  2012年   20篇
  2011年   24篇
  2010年   32篇
  2009年   31篇
  2008年   27篇
  2007年   12篇
  2006年   16篇
  2005年   23篇
  2004年   8篇
  2003年   9篇
  2002年   12篇
  2001年   11篇
  2000年   8篇
  1999年   11篇
  1998年   22篇
  1997年   42篇
  1996年   34篇
  1995年   27篇
  1994年   23篇
  1993年   23篇
  1992年   9篇
  1991年   12篇
  1990年   19篇
  1989年   37篇
  1988年   24篇
  1987年   14篇
  1986年   12篇
  1985年   8篇
  1984年   11篇
  1983年   13篇
  1982年   12篇
  1981年   8篇
  1980年   9篇
  1978年   4篇
  1977年   4篇
  1976年   6篇
  1952年   1篇
  1948年   1篇
  1894年   1篇
排序方式: 共有798条查询结果,搜索用时 15 毫秒
61.
62.
BACKGROUND/OBJECTIVE: To describe an apparent relationship between smoking and the neuropathic pain experience in people with spinal cord injury (SCI). METHOD: Case Reports. PARTICIPANTS/METHODS: Two individuals treated at a rehabilitation center. The first was a 38-year-old white man with a T1 2 SCI, American Spinal Injury Association (ASIA) impairment scale (AIS) A, secondary to motor vehicle crash. Duration of injury was 14 years. He reported burning pain in his legs, and has smoked 1/2 pack per day for the last 15 years. The second was a 55-year-old African American man with a T6 SCI, AIS A, secondary to gunshot wound. Duration of injury was 22 years. He was a 40-year 1/2 to 1 pack per day smoker, who, after injury, consistently experienced burning, radicular pain, rated 7/10, around the level of the injury. SUMMARY: The first subject rated his pain as 4/10 when not smoking and 7/10 when smoking. The pain subsided 30 minutes after smoking was discontinued. He noted an immediate increase in neuropathic pain when smoking. The second subject quit smoking for 1 month and immediately noted that the pain disappeared, rating it 0/10. After he resumed smoking, his radicular pain was 8.5/10 in the morning and 5/10 in afternoon. CONCLUSIONS: No similar reports have been published, based on a MEDLINE search. Nicotinic receptors have been implicated in pain perception. It is unclear to what extent these 2 cases generalize to the SCI population. We plan to explore this via survey and experimental research. Smoking cessation may have a dual benefit of increased health and decreased neuropathic pain.  相似文献   
63.
OBJECTIVE: To assess sacral and lower-extremity pinprick preservation as prognostic indicators for ambulation in motor complete, sensory incomplete spinal cord injury (SCI). DESIGN: Retrospective analysis. SETTING: Twenty-eight tertiary care centers in the United States and Canada. PARTICIPANTS: Subjects (N=131; mean age, 31.6y) with motor complete, sensory incomplete SCI. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURE: Ambulation at 26 and 52 weeks postinjury (modified Benzel scale). RESULTS: A higher percentage of subjects with sacral pinprick preservation at baseline were ambulating at 26 (39.4% vs 28.3%) and 52 weeks (53.6% vs 41.5%). This finding did not reach statistical significance. The presence of sacral pinprick preservation at 4 weeks postinjury was significant for predicting ambulation at 52 weeks postinjury (36.0% vs 4.4%, P =.011) and approached significance at 26 weeks (15.2% vs 0.0%, P =.056). Significant differences in ambulation rates were also observed between subjects, based on the presence of baseline lower-extremity pinprick preservation (>/=50% of lower-extremity L2-S1 dermatomes) at both 26 (50.0% vs 28.8%, P =.048) and 52 weeks (66.7% vs 40.3%, P =.023) after injury. CONCLUSIONS: Baseline lower-extremity pinprick preservation and sacral pinprick preservation at 4 weeks postinjury are associated with an improved prognosis for ambulation.  相似文献   
64.
In patients with ovarian carcinoma, the presence of metastatic disease in a retroperitoneal lymph node is indicative of a poor prognosis. Although a “staging laparotomy” is required for proper treatment, definitive information concerning para-aortic and pelvic lymph node metastasis often is not available. To determine the incidence of retroperitoneal lymph node metastases in untreated cases of ovarian carcinoma, a prospective study by selective nodal biopsy was undertaken in 61 unselected patients with the following distribution: Stage I, 11; Stage II, 10; Stage III, 31; and Stage IV, 9. The incidence of para-aortic node metastasis overall was 37.7% and of pelvic node metastasis, 14.8%. Of 23 patients with positive para-aortic nodes, 30.4% had no concomitant pelvic node involvement. Direct relationships between nodal metastasis and clinical stage, tumor grade, and histologic type of tumor were demonstrated. The incidence of positive para-aortic nodes in Stage I disease was 18.2%; in Stage II, 20.0%; in Stage III, 41.9%; and in Stage IV, 66.7%. The corresponding incidence of pelvic node metastasis was 9.1% in Stage I, 10.0% in Stage II, 12.9% in Stage III, and 33.3% in Stage IV. Grade 3 tumors were associated most frequently with nodal involvement, with an incidence of positive para-aortic nodes of 52.5% and of positive pelvic nodes of 15.5%. In patients with a serous type of malignancy, the frequencies of positive para-aortic/pelvic nodes were 44.4%/16.7%, respectively; in the undifferentiated type, 50.0%/10.0%; in the clear cell type, 25.0%/25.0%; and in the mucinous type, 14.3%/ 14.3%. In this small series, 32 patients (52.5%) had positive retroperitoneal nodal involvement. It is concluded that selective biopsies of the para-aortic and pelvic lymph nodes should be part of any “staging laparotomy” for ovarian carcinoma, and that the true incidence of nodal involvement in these patients awaits further investigation.  相似文献   
65.
66.

OBJECTIVE:

Inflammation plays an important role in the development of chronic lung disease (CLD), which has become a major cause of morbidity in surviving infants less than 1250 g at birth. The authors hypothesized that the progression of this inflammation and, therefore, the establishment of CLD would be decreased with the use of early prophylactic inhaled corticosteroids. Short, and long term respiratory and neurodevelopmental outcomes were also examined.

DESIGN:

A double-blind, randomized placebo controlled trial.

SETTING:

Level-III neonatal intensive care unit.

POPULATION STUDIED:

Sixty infants less than 1250 g at birth, diagnosed with respiratory distress syndrome and requiring ventilatory support at 72 h of age were enrolled in the study.

INTERVENTION:

Infants enrolled received either placebo or beclomethasone diproprionate by a metered dose inhaler, which was used in-line with the ventilator circuit while the infant was ventilated and then via a spacer until 28 days of age.

RESULTS:

Thirty infants were given beclomethasone and 30 were given placebo. There were two deaths in each group. Among the surviving infants, the frequency of moderate-to-severe CLD was 17% in each study group. Mean time to extubation was not different for beclomethasone compared with placebo at 16.4 and 12.5 days (P=0.12), respectively. The requirement for intravenous corticosteroids was lower in the beclomethasone-treated group (RR 0.67, 95% CI 0.43 to 1.04), although this difference was not statistically significant. The incidence of growth failure, infection and intraventricular hemmorhage did not differ between the two groups. Long term outcomes were not different with respect to the incidence of respiratory re-admissions, cerebral palsy, developmental delay, blindness or deafness.

CONCLUSIONS:

Early treatment with inhaled beclomethasone diproprionate did not reduce the incidence of CLD or decrease the duration of mechanical ventilation. The decrease in intravenous corticosteroid use was not statistically significant. Long term outcome was not affected.  相似文献   
67.
OBJECTIVE: To study the association between umbilical plasma levels of interleukin-6 (IL-6) in relation to fetal growth in subgroups of preeclampsia, and in control pregnancies. METHODS: Umbilical cord plasma was collected from 12,804 consecutive births. A total of 271 singleton cases of preeclampsia were identified, and classified as mild or severe, and as disease with early or late onset. As controls, 611 singleton pregnancies without preeclampsia were selected, and the ratio between observed and expected birth weight was used as a measure of fetal growth. In the analysis, we also included maternal smoking during pregnancy. Umbilical cord plasma IL-6 concentration was measured with an IL-6 bioassay. Comparing controls with subgroups of preeclampsia (severe and early onset), this study had a statistical power of 90% to detect a difference in cord IL-6 of 10 pg/mL. RESULTS: In severe preeclampsia, cord plasma IL-6 concentration was lower than among controls (P <.001), and there was a sharp decrease in cord plasma IL-6 with decreasing birth weight ratio (P trend <.001). By further dividing the preeclampsia group into early or late onset, the strong association between low IL-6 levels and low birth weight ratio appeared to be present mainly in early-onset disease. These results were not confounded by maternal smoking. CONCLUSION: Restricted fetal growth related to preeclampsia is associated with reduced umbilical cord plasma IL-6 concentration in cases with early-onset disease. In these cases, fetal growth restriction could be mediated by impaired trophoblast function.  相似文献   
68.
69.
ABSTRACT. Milt7eacute;nyi, M., Pohlandt, F., Bóka, G. and Kun, E. (2nd Department of Paediatrics, Semmelweis University, Medical School, Budapest, Hungary, and the Section of Neonatology, Centre of Paediatrics, University of Ulm, Federal Republic of Germany). Tubular proteinuria after perinatal hypoxia. Acta Paediatr Scand, 70:399, 1981.–Urinary total protein (UTP) and urinary protein pattern have been studied in 23 newborn infants with Apgar scores ±S3 at one minute or acidosis (pH ±7.15) on the first day. On the first and second day UTP excretion was increased in 13 out of 18 patients. At this time the excretion of low molecular weight microproteins (T-4 and T-5) was elevated in 12 patients without increased plasma urea concentration in any case. The increased excretion of the smallest microproteins T-4/T-5 is an early sign of an impaired tubular function.  相似文献   
70.
Clinically, there is strong rationale for developing a method which will provide a scientific basis for comparing the efficacy of one hyperthermia treatment with another. In order to accomplish this goal, methods must first be developed which will allow the clinician to know the three-dimensional temperature distribution in heated tissue. In this paper, examples of how this goal can be achieved are presented. Techniques for compensating for various modifiers of hyperthermia effectiveness are proposed. The limitations and advantages of these approaches are described and directions for future research are discussed.  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