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   658篇
  免费   32篇
  国内免费   33篇
儿科学   27篇
妇产科学   48篇
基础医学   45篇
口腔科学   38篇
临床医学   60篇
内科学   102篇
皮肤病学   3篇
神经病学   25篇
特种医学   56篇
外科学   132篇
综合类   37篇
预防医学   62篇
眼科学   4篇
药学   50篇
中国医学   1篇
肿瘤学   33篇
  2022年   2篇
  2021年   5篇
  2020年   2篇
  2019年   8篇
  2018年   5篇
  2017年   8篇
  2016年   3篇
  2015年   3篇
  2014年   18篇
  2013年   20篇
  2012年   17篇
  2011年   22篇
  2010年   17篇
  2009年   27篇
  2008年   47篇
  2007年   44篇
  2006年   32篇
  2005年   36篇
  2004年   27篇
  2003年   28篇
  2002年   19篇
  2001年   26篇
  2000年   16篇
  1999年   34篇
  1998年   18篇
  1997年   19篇
  1996年   19篇
  1995年   14篇
  1994年   26篇
  1993年   17篇
  1992年   13篇
  1991年   17篇
  1990年   13篇
  1989年   16篇
  1988年   13篇
  1987年   11篇
  1986年   10篇
  1985年   9篇
  1984年   3篇
  1983年   3篇
  1982年   3篇
  1981年   11篇
  1980年   3篇
  1979年   3篇
  1978年   1篇
  1977年   3篇
  1976年   3篇
  1975年   6篇
  1968年   1篇
  1954年   1篇
排序方式: 共有723条查询结果,搜索用时 15 毫秒
1.
Background: Bupivacaine retards myocardial acidosis during ischemia. The authors measured function of rat isolated hearts after prolonged storage to determine whether bupivacaine improves cardiac protection compared with standard cardioplegia alone.

Methods: After measuring cardiac function on a Langendorff apparatus, hearts were perfused with cardioplegia alone (controls), cardioplegia containing 500 [mu]m bupivacaine, or cardioplegia containing 2 mm lidocaine; were stored at 4[degrees]C for 12 h; and were then reperfused. Heart rate and left ventricular developed pressures were measured for 60 min. Maximum positive rate of change in ventricular pressure, oxygen consumption, and lactate dehydrogenase release were also measured.

Results: All bupivacaine-treated, four of five lidocaine-treated, and no control hearts beat throughout the 60-min recovery period. Mean values of heart rate, left ventricular developed pressure, maximum positive rate of change in ventricular pressure, rate-pressure product, and efficiency in bupivacaine-treated hearts exceeded those of the control group (P < 0.001 at 60 min for all). Mean values of the lidocaine group were intermediate. Oxygen consumption of the control group exceeded the other groups early in recovery, but not at later times. Lactate dehydrogenase release from the bupivacaine group was less than that from the control group (P < 0.001) but did not differ from baseline.  相似文献   

2.
Neuroimaging in Pineal Tumors   总被引:4,自引:0,他引:4  
F Reis  MD  AV Faria  MD  PhD  VA Zanardi  MD  PhD  JR Menezes  MD  F Cendes  MD  PhD  LS Queiroz  MD  PhD 《Journal of neuroimaging》2006,16(1):52-58
BACKGROUND AND PURPOSE: The authors report radiological findings in 11 tumors in the pineal region, which were histologically diagnosed as germinomas, pineocytomas pineoblastomas, ependymomas, teratomas, and astrocytomas. METHODS: Computed tomography (CT) was performed in seven patients and magnetic resonance imaging (MRI) was performed in all patients. RESULTS: CT showed a solid or solid/cystic mass with variable contrast enhancement. MRI showed a heterogeneous mass, with hypointense signal on T1 and iso/hyperintense signal on T2-weighted images (WI) and gadolinium enhancement. Extension to adjacent structures occurred in five patients and spread through the cerebral spinal fluid (CSF) in two. CONCLUSIONS: Pineal region tumors have no pathognomonic imaging pattern. MRI and CT are complementary in diagnosis and are important to determine localization, extension, and meningeal spread.  相似文献   
3.
4.
A comparative chronic inhalation exposure study was performed to investigate the potential health effects of gasoline and ethanol engine exhaust fumes. Test atmospheres of gasoline and ethanol exhaust were given to Wistar rats and Balb C mice housed in inhalation chambers for a period of 5 weeks. Gas concentration and physical parameters were continually monitored during the exposure period. Several biological parameters were assessed after the exposure including pulmonary function, mutagenicity, and hematological, biochemical, and morphological examinations. The results demonstrated that the chronic toxicity of the gasoline-fueled engine is significantly higher than that of the ethanol engine.  相似文献   
5.
6.
The effect of nine obstacles on family physicians' screening practices is reported. Family physicians, responding to a survey of periodic health screening practices, were asked to check the obstacles that affected their use of the screening tests listed. In the survey, 129 members of the American Academy of Family Physicians and 146 members of the Society of Teachers of Family Medicine responded. The most frequently reported obstacles to screening were cost to the patient, patient refusal, inconvenience to the patient, and lack of facilities or equipment. The tests for which the most obstacles were reported were sigmoidoscopy, tonometry, and mammography. The Society of Teachers of Family Medicine physicians were more likely to list cost, patient reluctance, inconvenience to the patient, "the literature does not recommend to use the test," time to perform the tests, and high rate of false positives and negatives. American Academy of Family physicians were more likely to report two obstacles, lack of facilities or equipment and risk to the patient. An analysis of the relationship between obstacle report and test utilization indicated that for only five of the nine obstacles were physicians who listed the obstacle less likely to use the test than physicians who did not list the obstacle. Obstacles related with decreased test use were those that affected the physician's ability to perform the test or the efficacy of the test itself while "inactive" obstacles were those that more directly affected and emanated from patients.  相似文献   
7.
8.
This work was designed to evaluate the role of intestinal parasites on nutritional status in three rural areas of Brazil. A total of 520 children aged 1–12 years were studied through a questionnaire concerning housing, socio-economic conditions and a 24-h food intake recall. Measurements of weight and height were also performed, and three stool samples were collected on consecutive days for parasitological analysis. Scores of the standard deviation (z-scores) for the weight-for-height and height-for-age were used to characterise the growth profile. A high prevalence of intestinal parasites was detected, with Giardia lamblia (44%), Endolimax nana (43%), Ascaris lumbricoides (41%) and Trichuris trichiura (40%) being the most prevalent. Eleven per cent of the children were classified as showing stunting. Inadequate daily caloric intake was observed in 78% of the population and the proportion of those with inadequate protein intake was 34%. Logistic regression analysis was employed for the multivariate study. Stunting was significantly associated with estimators of low economic income, inadequate protein intake and polyparasitism, especially the association between Ascaris lumbricoides and Trichuris trichiura .  相似文献   
9.
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