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   39449篇
  免费   2146篇
  国内免费   239篇
耳鼻咽喉   581篇
儿科学   730篇
妇产科学   812篇
基础医学   5112篇
口腔科学   2447篇
临床医学   3117篇
内科学   9613篇
皮肤病学   795篇
神经病学   3515篇
特种医学   1074篇
外科学   5206篇
综合类   124篇
一般理论   13篇
预防医学   2980篇
眼科学   473篇
药学   2764篇
  1篇
中国医学   214篇
肿瘤学   2263篇
  2023年   304篇
  2022年   762篇
  2021年   1285篇
  2020年   809篇
  2019年   1086篇
  2018年   1300篇
  2017年   997篇
  2016年   1060篇
  2015年   1260篇
  2014年   1706篇
  2013年   2063篇
  2012年   3189篇
  2011年   3335篇
  2010年   1860篇
  2009年   1530篇
  2008年   2610篇
  2007年   2557篇
  2006年   2267篇
  2005年   2156篇
  2004年   1946篇
  2003年   1738篇
  2002年   1555篇
  2001年   420篇
  2000年   400篇
  1999年   364篇
  1998年   252篇
  1997年   236篇
  1996年   220篇
  1995年   194篇
  1994年   180篇
  1993年   148篇
  1992年   188篇
  1991年   152篇
  1990年   137篇
  1989年   124篇
  1988年   123篇
  1987年   109篇
  1986年   98篇
  1985年   98篇
  1984年   97篇
  1983年   101篇
  1982年   76篇
  1981年   70篇
  1980年   81篇
  1979年   60篇
  1978年   50篇
  1977年   42篇
  1976年   30篇
  1975年   29篇
  1968年   38篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
This double-blind study compared ampicillin-sulbactam 3 g versus cefoxitin 2 g in 136 adult patients at risk for developing an infection after abdominal surgery. Separate randomization schedules were used for colorectal, upper gastrointestinal/biliary, and other abdominal procedures. Study antibiotics were administered within 30 minutes before incision and repeated 6 hours later. Patients having colorectal surgery received a third dose of antibiotic 6 hours after the second. Efficacy evaluations were made on 123 patients, 62 in the ampicillin-sulbactam group and 61 in the cefoxitin group. The overall postoperative infection rates were 12.9% for ampicillin-sulbactam and 9.8% for cefoxitin (p>0.05); one wound infection occurred in each group. Adverse events were experienced by 13.2% of the ampicillin-sulbactam and 19.1% of the cefoxitin recipients (p>0.05). Cost-minimization analysis revealed that ampicillin-sulbactam was a cost-effective alternative to cefoxitin for the prevention of infection after abdominal surgery.  相似文献   
22.
The author describes his surgical approach to the problems of the aging upper arm and elbow region. Surgery at an appropriate age can prevent the progressive wrinkling of the elbow which is further aggravated by aging of the upper arm. The author's operation is aimed at correcting both portions of the arm anatomy at the same time.  相似文献   
23.
Hepatitis B virus (HBV) recurrence after liver transplantation is significantly reduced by prophylaxis with hepatitis B immune globulins (HBIG) or antiviral drugs in nonreplicating patients and by the combination of both drugs in replicating patients. However, the load of HBV DNA, which defines replicating status in patients undergoing liver transplantation, remains unclear. This study analyzes the correlation between the viral load, tested with a single amplified assay, at the time of liver transplantation, and the risk of hepatitis B recurrence in 177 HBV carriers who underwent transplantation in a single center from 1990 to 2002. Overall, HBV relapsed after surgery in 15 patients (8.5%) with a 5- and 8-year actuarial rate of recurrence of 8% and 21%, respectively. After liver transplantation hepatitis B recurred in 9% of 98 selected subjects treated only with immune globulins and in 8% of 79 viremic patients who received immune globulins and lamivudine (P = NS). A linear correlation was observed between recurrence and viral load at the time of surgery. In transplant patients with HBV DNA higher than 100,000 copies/mL, 200-99,999 copies/mL, and DNA undetectable by amplified assay, hepatitis B recurred in 50%, 7.5%, and 0% of patients, respectively. Overall, a viral load higher than 100,000 copies/mL at the time of liver transplantation was significantly associated with hepatitis B recurrence (P = .0003). In conclusion, spontaneous or antiviral-induced HBV DNA viral load at the time of surgery classifies the risk of HBV recurrence after liver transplantation and indicates the best prophylaxis strategy.  相似文献   
24.
Atrial electrical remodeling plays a part in recurrence of atrial fibrillation (AF). It has been related to an increase in heterogeneity of atrial refractoriness that facilitates the occurrence of multiple reentry wavelets and vulnerability to AF. AIM: To examine the relationship between dispersion of atrial refractoriness (Disp_A) and vulnerability to AF induction (A_Vuln) in patients with clinical paroxysmal AF (PAF). METHODS: Thirty-six patients (22 male; age 55+/-13 years) with > or =1 year of history of PAF (no underlying structural heart disease--n=20, systemic hypertension--n=14, mitral valve prolapse--n=1, surgically corrected pulmonary stenosis--n=1), underwent electrophysiological study (EPS) while off medication. The atrial effective refractory period (AERP) was assessed at five different sites--high (HRA) and low (LRA) lateral right atrium, high interatrial septum (IAS), proximal (pCS) and distal (dCS) coronary sinus--during a cycle length of 600 ms. AERP was taken as the longest S1-S2 interval that failed to initiate a propagation response. Disp_A was calculated as the difference between the longest and shortest AERP. A_Vuln was defined as the ability to induce AF with 1-2 extrastimuli or with incremental atrial pacing (600-300 ms) from the HRA or dCS. The EPS included analysis of focal electrical activity based on the presence of supraventricular ectopic beats (spontaneous or with provocative maneuvers). The patients were divided into group A--AF inducible (n=25) and group B--AF not inducible (n=11). Disp_A was analyzed to determine any association with A_Vuln. Disp_A and A_Vuln were also examined in those patients with documented repetitive focal activity. Logistic regression was used to determine any association of the following variables with A_Vuln: age, systemic hypertension, left ventricular hypertrophy, left atrial size, left ventricular function, duration of PAF, documented atrial flutter/tachycardia and Disp_A. RESULTS: There were no significant differences between the groups with regard to clinical characteristics and echocardiographic data. AF was inducible in 71% of the patients and noninducible in 29%. Group A had greater Disp_A compared to group B (105+/-78 ms vs. 49+/-20 ms; p=0.01). Disp_A was >40 ms in 50% of the patients without A_Vuln and in 91% of those with A_Vuln (p=0.05). Focal activity was demonstrated in 14 cases (39%), 57% of them with A_Vuln. Disp_A was 56+/-23 ms in this group and 92+/-78 ms in the others (p=0.07). Using logistic regression, the only predictor of A_Vuln was Disp_A (p=0.05). CONCLUSION: In patients with paroxysmal AF, Disp_A is a major determinant of A_Vuln. Nevertheless, the degree of nonuniformity of AERP appears to be less important as an electrophysiological substrate for AF due to focal activation.  相似文献   
25.
BACKGROUND: This study evaluated the prevalence of the atherogenic metabolic triad and the hypothesis that waist circumference and fasting triglyceride concentrations could be used as screening tools for identification of the atherogenic metabolic triad in a population of heart transplant men. It also evaluated the relationship between the atherogenic metabolic triad and coronary artery disease (CAD). METHODS: In the study group of 83 consecutive male heart transplant patients having their routine annual coronarography, 23 patients (28%) were characterized by the atherogenic metabolic triad defined by the presence of elevated fasting insulin and apolipoprotein B concentrations and by small low-density lipoprotein (LDL) particles. RESULTS: Seventy-seven per cent of patients with waist circumference values >/= 90 cm and with elevated triglyceride levels (>/=2.0 mmol/liter) were characterized by this atherogenic metabolic triad. Patients with the atherogenic metabolic triad were at markedly increased risk of CAD (odds ratio of 25.3, 95% CI: 1.11-577.3, p < 0.04) compared to heart transplant patients without the atherogenic metabolic triad. CONCLUSIONS: About 30% of heart transplant patients showed the features of the atherogenic metabolic triad. Measurement and interpretation of waist circumference and fasting triglycerides could be used among heart transplant patients to early identify men characterized by the presence of elevated fasting insulin and apolipoprotein B concentrations and small LDL particles. The presence of the atherogenic metabolic triad identified patients at high risk of CAD even in the heart transplant population.  相似文献   
26.
Left ventricular geometry is distorted after anterior infarction caused by occlusion of a wrap around left anterior descending artery. Loss of the apex creates a spherical left ventricular (LV) chamber, whose rebuilding requires reconstruction techniques that exclude the non-functional inferior wall. The described technique of tailoring the apex defines a way to create an oblique elliptical rim for subsequent patch placement to complete the restoration procedure. This method of ventricular rebuilding differs from methods that follow the inferior wall scar, which result in a restoration procedure that leaves a spherical or box-like apical region.  相似文献   
27.
The aim of our study was to investigate the metabolic effect of telmisartan and irbesartan in subjects treated with rosiglitazone, a well-known insulin-sensitizing drug, in order to clarify the direct metabolic effects of the two former drugs. Patients were enrolled, evaluated, and followed at 3 Italian centers. We evaluated 188 type 2 diabetic patients with metabolic syndrome (94 males and 94 females in total; 49 males and 46 females, aged 56+/-5, treated with telmisartan; and 45 males and 48 females, aged 55+/-4, treated with irbesartan). All had been diabetic for at least 6 months, and glycemic control by the maximum tolerated dietary changes and maximum tolerated dose of oral hypoglycemic agents had been attempted and failed in all cases. All patients took a fixed dose of rosiglitazone, 4 mg/day. We administered telmisartan (40 mg/day) or irbesartan (150 mg/day) in a randomized, controlled, double-blind clinical manner. We evaluated body mass index (BMI), glycemic control (HbA1c fasting plasma glucose and insulin levels [FPG, and FPI, respectively], and homeostasis model assessment [HOMA] index), lipid profile (total cholesterol [TC], low density lipoprotein-cholesterol [LDL-C], high density lipoprotein-cholesterol [HDL-C], and triglycerides [TG]), systolic and diastolic blood pressure (SBP and DBP), tumor necrosis factor-alpha (TNF-alpha), and leptin during the 12 months of this treatment. No BMI change was observed after 6 or 12 months in either group. Significant decreases in HbAlc and FPG were observed after 6 months in the telmisartan group, and after 12 months in both groups. The decrease in HbA1c and FPG at 12 months was statistically significant only in the telmisartan group. A significant decrease in FPI was observed at 12 months in both groups, and this decrease was significantly greater in the telmisartan group. Significant decreases in the HOMA index were observed at 6 and 12 months in both groups, and the decrease in the HOMA index after 12 months was significantly greater in the telmisartan group than in the irbesartan group. Significant changes in SBP, DBP, TC, and LDL-C were observed after 6 and 12 months in both groups. Significant decreases in TNF-alpha and leptin levels were observed after 6 months in the telmisartan group, and after 12 months in both groups. In conclusion, in this study of patients with type 2 diabetes mellitus and metabolic syndrome, telmisartan seemed to result in a greater improvement in glycemic and lipid control and metabolic parameters related to metabolic syndrome compared to irbesartan. These observed metabolic effects of different angiotensin type 1 receptor blockers could be relevant when choosing a therapy to correct metabolic derangement of patients affected by metabolic syndrome and diabetes.  相似文献   
28.
29.
30.
Ohne Zusammenfassung Rechtsreferendar Mario Kaufmann, Wiss. Hilfskraft am Lehrstuhl für V?lkerrecht, Europarecht, Europ?isches und Internationales Wirtschaftsrecht (Prof. Dr. Stephan Hobe) an der Universit?t zu K?ln, Neusser Stra?e 285, D-50733 K?ln  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