首页 | 官方网站   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   13149篇
  免费   598篇
  国内免费   89篇
医药卫生   13836篇
  2023年   121篇
  2022年   98篇
  2021年   432篇
  2020年   241篇
  2019年   314篇
  2018年   404篇
  2017年   284篇
  2016年   436篇
  2015年   498篇
  2014年   632篇
  2013年   706篇
  2012年   906篇
  2011年   906篇
  2010年   535篇
  2009年   475篇
  2008年   896篇
  2007年   1022篇
  2006年   982篇
  2005年   908篇
  2004年   795篇
  2003年   636篇
  2002年   566篇
  2001年   153篇
  2000年   130篇
  1999年   118篇
  1998年   77篇
  1997年   49篇
  1996年   59篇
  1995年   35篇
  1994年   24篇
  1993年   22篇
  1992年   33篇
  1991年   27篇
  1990年   27篇
  1989年   34篇
  1988年   27篇
  1987年   24篇
  1986年   20篇
  1985年   22篇
  1984年   10篇
  1983年   13篇
  1982年   8篇
  1981年   8篇
  1980年   7篇
  1979年   11篇
  1978年   10篇
  1973年   10篇
  1972年   11篇
  1971年   9篇
  1966年   8篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
31.
The early (Fernandez) and late (Mitsuda) lepromin reactions were closely examined in a group of healthy, BCG-vaccinated individuals who were given four doses of a heat-killed, armadillo-derived vaccine, i.e., 1.5 X 10(7), 5 X 10(7), 1.5 X 10(8), and 5 X 10(8) bacilli. There was a clear dose-response relationship for both the early and late reactions with no leveling of the responses within the range of doses examined. While the early response was negative in most of the volunteers, the late response was positive in all of the volunteers. No association was found between the early lepromin test and the pre-vaccination skin test to PPD. There was also no association between the early lepromin test and the pre-vaccination skin test response to a soluble Mycobacterium leprae antigenic preparation (MLSA) in general, but there was a good correlation between these two parameters at the highest vaccine dose. The late lepromin response showed no association with either the prevaccination or post-vaccination skin test response to PPD. However, there was a significant correlation between the late lepromin response and the post-vaccination skin test response to MLSA. In general, no association could be found between the in vivo skin tests and the in vitro lymphocyte transformation test (LTT). Thus, the lepromin test is essentially a vaccination which elicits a specific response to M. leprae antigens provided that the dose of armadillo lepromin given is higher than 5 X 10(7). Therefore, it is unsuitable as a diagnostic test for leprosy.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
32.
Death certificates from 23,890 male and female non-Hodgkin's lymphoma (NHL) cases and 119,450 noncancer controls from 24 states for the period 1984-1989 were used to generate hypotheses regarding occupational associations. Cases were frequency matched by age, race, and gender with five controls per case. Odds ratios were calculated for 231 industries and 509 occupations. Significant associations were observed for a variety of white-collar professionals (i.e., real estate agents, secretaries, bookkeepers, teachers, postal employees, business agents, engineers, chemists, and medical professionals) and blue-collar occupations (i.e., firefighters, farm managers, aircraft mechanics, electronic repairers, mining machine operators, and crane and tower operators). © 1995 Wiley-Liss, Inc.  相似文献   
33.
BACKGROUND: The aim of this study was to determine whether prophylactic use of calcium dobesilate (CD) can improve venous function after saphenous vein harvest in coronary artery bypass graft (CABG). MATERIALS AND METHODS: A total of 100 patients who underwent elective CABG were divided into four equal groups. In Group A, the greater saphenous vein (GSV) was harvested below the knee and, in Group B, through the knee till the groin. These patients remained untreated. Group C received CD in a dosage of 1500 mg po daily after the GSV was harvested below the knee. Group D received same dosage of CD after the GSV was harvested through the knee till the groin. Venous function of ipsilateral leg was evaluated clinically and by Doppler ultrasonography in the postoperative first week and second month. RESULTS: Clinical findings of venous insufficiency were observed with a similar rate between groups at both early and late periods. In Groups A and B, after 2 months, flow velocities decreased and reflux periods increased significantly. In groups C and D, treatment with CD for 2 months after saphenectomy resulted in a significant increase in flow velocities and a significant decrease in reflux periods. Patients in Groups B and D have significantly more impaired venous functions. CONCLUSION: Saphenectomy results in ipsilateral leg venous dysfunction, which seems to be unrelated to leg swelling and to be more prominent in patients with high-level saphenectomy. In addition, to be careful about the restriction of the saphenectomy procedure into the most appropriate level, prophylactic use of CD can prevent this deterioration when it was added to varice socks.  相似文献   
34.
35.
Severe middle vault deformity with disturbed nasal form and function is one of the most challenging procedures to correct in a secondary rhinoplasty. Reconstructing the deformity with autologous septal cartilage would be the primary choice of most surgeons, if it were always available. However in certain cases the lack of a sufficient quantity of autologous cartilage has forced surgeons to explore other viable options. This paper discusses our experience with the combined use of spreader and dorsal onlay grafts from various materials in the reconstruction of severe middle vault deformity in 110 patients. In follow up, (between 6 and 42 months; mean 21 months) all patients were noted to have improved in both aesthetics and function with no major complications noted. In summary, this study proposes that any engrafting material can be used safely when the proper surgical principals and technique are employed.  相似文献   
36.
Background  Reduced left ventricular ejection fraction (LVEF) is a risk factor for poor outcomes in patients with coronary artery disease (CAD). Mental stress-induced myocardial ischemia (MSIMI) also identifies a subset of CAD patients at increased risk for future cardiovascular events. Susceptibility to MSIMI in patients with CAD and reduced LVEF is unknown. Methods and Results  We enrolled 182 patients (67 women) with a mean age of 64 years and a documented history of CAD in this study. Baseline resting ejection fraction was determined by use of technetium 99m sestamibi gated single photon emission computed tomography. Abnormal LVEF was defined as less than 45% for men and less than 50% for women (based on published norms for our software [Cedars-Sinai Medical Center]). All participants underwent mental stress testing with a public speaking task. Rest/stress myocardial perfusion single photon emission computed tomography was performed via conventional methodology. Images were visually compared for number and severity of perfusion defects by use of a scoring method from 0 to 4. A summed difference score was calculated as the difference between summed stress and rest scores. A score of greater than 3 was considered abnormal. MSIMI developed in 19% of patients with normal LVEF and 31% of those with reduced LVEF. There is no statistically significant difference between the two groups (P=.11). Conclusions  CAD patients with left ventricular dysfunction are equally susceptible to MSIMI as those with normal LVEF. This study was supported by grants HL 070265 and HL 072059 from the National Heart. Lung, and Blood Institute. This material is also the result of work supported by resources and with the use of facilities at the Department of Veterans. Affairs Medical Center, Gainesville, Fla.  相似文献   
37.
Encephalopathy is a common complication of sepsis. However, little is known about the morphological changes that occur in the brain during sepsis. In this study, fecal peritonitis was induced in Wistar rats, which had been monitored for 4 h before their brains were removed and samples from the CA1 area taken. In addition to higher blood pressure with a decreasing pattern and a significant drop in rectal temperature, an increased heart rate and marked respiratory failure were observed. The tissue was investigated and compared with corresponding hippocampal samples taken from sham‐operated and not operated control groups. Significantly more peri‐microvascular edema was found in the hippocampal CA1 area in the septic group. The percentages of the peri‐microvascular edema were 158.57 ± 3.6%, 122.84 ± 1.5% and 120.24 ± 1.9% in the fecal peritonitis group, sham‐operated and not operated control groups, respectively. The results may suggest that the edema observed around the microvessels may participate in the pathogenesis of the septic encephalopathy probably by causing in the microvascular permeability characteristics.  相似文献   
38.
39.
Study Objective: To test the hypothesis that the magnitude of the acute hemodynamic response to electroconvulsive therapy (ECT) is related to the duration of the seizure activity in patients receiving different dosages of intravenous (IV) lidocaine.

Design: Randomized, double-blind, placebo-controlled, cross-over study.

Setting: University-affiliated hospital.

Patients: 21 ASA physical status I, II, and III patients undergoing four consecutive maintenance ECT treatments for chronic depression.

Interventions: Patients received lidocaine 50 mg, 100 mg, 200 mg IV, or saline prior to induction of anesthesia via a standardized anesthetic technique.

Measurements and Main Results: Noninvasive blood pressure (BP) and heart rate (HR), as well as the duration of motor and electroencephalographic (EEG) seizure, were measured. The duration of motor and EEG seizures (means ± SD) were 37 ± 13 sec and 64 ± 21 sec, 25 ± 11 sec and 52 ± 43 sec, 17 ± 12 sec and 32 ± 17 sec, 1 ± 3 sec and 18 ± 10 sec in the saline, lidocaine 50 mg, 100 mg, 200 mg groups, respectively. Although the duration of seizure activity was decreased in a dose-related fashion after lidocaine pretreatment, the peak increases in BP and HR were similar in the lidocaine and saline treatment groups.

Conclusions: Despite producing dose-related decreases in the duration of both motor and EEG seizure activity, lidocaine failed to attenuate the acute hemodynamic response to ECT. Thus, the acute hemodynamic response to ECT is not related to the duration of seizure activity.  相似文献   

40.
OBJECTIVE: We wanted to compare the efficacies of 95% ethanol and 20% hypertonic saline (HS) sclerotherapies that were performed in a single session under CT guidance for the management of simple renal cysts. MATERIALS AND METHODS: A prospective series of 74 consecutive patients (average age: 57.6 +/- 8.1 years) with simple renal cysts were enrolled in this study. They were randomized into two groups and 95% ethanol or 20% HS, respectively, corresponding to 25% of the aspiration volume, was injected. Treatment success was determined six months later with follow-up clinical evaluation and performing ultrasonography. RESULTS: The sclerotherapy was accepted as technically successful without major complications in all except two patients who were excluded because of a communication between the simple renal cyst and the pelvicalyceal collecting system. Thirty-six patients in the ethanol group received sclerotherapy with 95% ethanol and 36 patients in the HS group underwent sclerotherapy with 20% HS. The complete regression ratio of the ethanol group was significantly higher (94% versus 72%, respectively) than that of the HS group. There was one patient with partial regression in each group. The failure ratio of the ethanol group was significantly lower (3% versus 25%, respectively) than that of the HS group. CONCLUSION: Ethanol sclerotherapy under CT guidance is a successful and safe procedure and it can be used for the treatment of simple renal cysts. Sclerotherapy with 95% ethanol is more effective than 20% HS sclerotherapy. Sclerotherapy with HS may be an option for patients preferring to undergo a less painful treatment procedure.  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-23

京公网安备 11010802026262号