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   84256篇
  免费   4103篇
  国内免费   475篇
耳鼻咽喉   1012篇
儿科学   1590篇
妇产科学   1988篇
基础医学   10428篇
口腔科学   3704篇
临床医学   6454篇
内科学   22487篇
皮肤病学   1651篇
神经病学   7226篇
特种医学   1931篇
外科学   11633篇
综合类   378篇
一般理论   25篇
预防医学   6087篇
眼科学   1594篇
药学   5289篇
中国医学   288篇
肿瘤学   5069篇
  2024年   67篇
  2023年   584篇
  2022年   962篇
  2021年   2208篇
  2020年   1195篇
  2019年   1963篇
  2018年   3061篇
  2017年   1977篇
  2016年   2070篇
  2015年   2496篇
  2014年   3106篇
  2013年   4266篇
  2012年   7195篇
  2011年   7236篇
  2010年   3914篇
  2009年   3129篇
  2008年   6080篇
  2007年   6257篇
  2006年   5894篇
  2005年   5761篇
  2004年   5134篇
  2003年   4634篇
  2002年   4221篇
  2001年   407篇
  2000年   300篇
  1999年   421篇
  1998年   477篇
  1997年   414篇
  1996年   375篇
  1995年   365篇
  1994年   290篇
  1993年   232篇
  1992年   197篇
  1991年   157篇
  1990年   132篇
  1989年   116篇
  1988年   85篇
  1987年   76篇
  1986年   96篇
  1985年   99篇
  1984年   112篇
  1983年   91篇
  1982年   140篇
  1981年   91篇
  1980年   109篇
  1979年   51篇
  1978年   60篇
  1977年   46篇
  1976年   47篇
  1974年   49篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
The effects of diet on inflammation: emphasis on the metabolic syndrome.   总被引:3,自引:0,他引:3  
Reducing the incidence of coronary heart disease with diet is possible. The main dietary strategies include adequate omega-3 fatty acids intake, reduction of saturated and trans-fats, and consumption of a diet high in fruits, vegetables, nuts, and whole grains and low in refined grains. Each of these strategies may be associated with lower generation of inflammation. This review examines the epidemiologic and clinical evidence concerning diet and inflammation. Dietary patterns high in refined starches, sugar, and saturated and trans-fatty acids, poor in natural antioxidants and fiber from fruits, vegetables, and whole grains, and poor in omega-3 fatty acids may cause an activation of the innate immune system, most likely by an excessive production of proinflammatory cytokines associated with a reduced production of anti-inflammatory cytokines. The whole diet approach seems particularly promising to reduce the inflammation associated with the metabolic syndrome. The choice of healthy sources of carbohydrate, fat, and protein, associated with regular physical activity and avoidance of smoking, is critical to fighting the war against chronic disease. Western dietary patterns warm up inflammation, while prudent dietary patterns cool it down.  相似文献   
62.
BACKGROUND: Portugal has one of the highest mortality rates from stroke, a high prevalence of hypertension and probably a high salt intake level. AIM: To evaluate Portuguese salt intake levels and their relationship to blood pressure and arterial stiffness in a sample of four different adult populations living in northern Portugal. METHODS: A cross-sectional study evaluating 24-hour urinary excretion of sodium (24 h UNa+), potassium and creatinine, blood pressure (BP), and pulse wave velocity (PWV) as an index of aortic stiffness in adult populations of sustained hypertensives (HT), relatives of patients with previous stroke (Fam), university students (US) and factory workers (FW), in the context of their usual dietary habits. RESULTS: We evaluated a total of 426 subjects, mean age 50 +/- 22 years, 56% female, BMI 27.9+/-5.1, BP 159/92 mmHg, PWV 10.4+/-2.2 m/s, who showed mean 24h UNa+ of 202 +/- 64 mmol/d, corresponding to a daily salt intake of 12.3 g (ranging from 5.2 to 24.8). The four groups were: HT: n = 245, 49 +/- 18 years, 92% of those selected, 69% treated, BP 163/94 mmHg, PWV 11.9 m/s, 24 h UNa+ 212 mmol/d, i.e. 12.4 g/d of salt); Fam: n = 38, 64 +/- 20 years, 57 % of those selected, BP 144/88 mmHg, PWV 10.5 m/s, 24 h UNa+ 194 mmol/d, i.e. 11.1 g/d of salt; US: n = 82, 22 +/- 3 years, 57% of those selected, BP 124/77 mmHg, PWV 8.7 m/s, 24h UNa+ 199 mmol/d, i.e. 11.3 g/d of salt; FW: n = 61, 39 9 years, 47% of those selected, BP 129/79 mmHg, PWV 9.5 m/s, 24 h UNa+ 221 mmol/d, i.e. 12.9 g/d of salt. The ratio of urinary sodium/potassium excretion (1.9 (0.4) was significantly higher in HT than the other three groups. In the 426 subjects, 24h UNa+ correlated significantly (p < 0.01) with systolic BP (r = 0.209) and with PWV (r=0.256) after adjustment for age and BP. Multivariate analysis showed that BP, age and 24h UNa+ correlated independently with PWV taken as a dependent variable. CONCLUSIONS: Four different Portuguese populations showed similarly high mean daily salt intake levels, almost double those recommended by the WHO. Overall, high urinary sodium excretion correlated consistently with high BP levels and appeared to be an independent determining factor of arterial stiffness. These findings suggest that Portugal in general has a high salt intake diet, and urgent measures are required to restrict salt consumption in order to prevent and treat hypertensive disease and to reduce overall cardiovascular risk and events.  相似文献   
63.
The authors studied quality control procedures at human milk banks and nutritional profiles of 909 milk samples (from 195 donors, aged 15 to 45 years) from banked human milk (BHM) in Brasília, Brazil. Number of donations per donor ranged from 1 to > 10 that consisted mostly of mature milk (90.9%) with a mean total energy of 529 +/- 85 kcal/L and a mean total lipid of 22.7 g/L +/- 13.2. Microbiological quality (titrable acidity-Dornic, degrees D) was suitable for infant feeding in 99.2% of samples (< 8 degrees D), ranging from 2 degrees D to 8 degrees D (mean 4.8 +/- 1.4 degrees D). Most BHM (98.1%) samples were dispensed to inpatient infants (1-7 days) diagnosed with respiratory distress (30.1%), prematurity (20.7%), metabolic distress (16.0%), jaundice (14.4%), bacterial infection (6.0%), pneumonia (3.3%), congenital cardiac distress (2.2%), or other conditions (6.2%). Well-motivated mothers and trained staff are serving and sustaining an important life-saving network with long-lasting impact on public health.  相似文献   
64.
BACKGROUND: Coronary vasculopathy is the main cause of cardiac graft failure. Because yearly coronary angiography is invasive in children, a non-invasive method for detecting graft vasculopathy is needed. The aim of this study was to test dobutamine-stress echocardiography in a pediatric population to determine its feasibility, safety and reliability in the detection of graft coronary artery disease. METHODS: Eighteen patients, aged 2 days to 16.8 years at transplantation (mean 8.4 years), underwent 44 dobutamine-stress echocardiography (DSE) exams, at a follow-up of 1.1 to 11.8 years (mean 5.1 years). Selective coronary angiography was performed for comparison. Echocardiographic recordings were obtained in 4 standard views of the left ventricle and measurements carried out within the frames of a 16-segment model. Segmental scores of contractility were obtained for each segment and a total segmental contractility index was calculated at each stage. RESULTS: All patients reached the maximum dose stage. Maximum heart rate was 57% to 90% of predicted maximum. Maximum systolic blood pressure reached 190 mmHg. Segmental scores were normal in 37 and abnormal in 7 cases. Echographic results were concordant with angiography in 82% and discordant in 18% of the cases (4 negative DSEs with minor angiographic lesions, 2 positive DSEs with normal angiography), but there was no significant angiographic lesion with normal DSE. CONCLUSIONS: DSE is a safe and highly feasible non-invasive technique in transplanted children. A normal DSE study successfully predicts the absence of significant coronary artery disease in the post-transplant population.  相似文献   
65.
66.
We studied NK cell function in eight patients with pathological hyperprolactinemia by measuring51Cr release by K562 cells exposed to their mononuclear cells and found it decreased compared to normal controls (P<0.01). Bromocriptine (BrC) treatment corrected NK function but also made it more efficient at 12:1 than at 25:1 or 50:1 effector:target ratios (ANOVA;P=0.01). The study of NK cell function in agarose revealed that its decrease in hyperprolactinemia is due to their low active binding to target cells, active killing, and recycling capacity. BrC tended to correct them but also increased recycling capacity to levels higher than those of controls (P<0.05). Sequential studies in three hyperprolactinemic patients before and after BrC showed correction of NK function within 1 week but its increased efficiency at the 12:1 effector:target ratio required 8 weeks. We conclude that hyperprolactinemia decreases NK cell function. BrC corrects this by decreasing prolactin levels but also makes NK function more efficient by increasing the capacity of NK cells to recycle after killing.  相似文献   
67.
Background Sympathectomy is the treatment of choice for primary hyperhidrosis. One curious occurrence that is difficult to explain from an anatomophysiological point of view in cases of video-assisted thoracoscopic sympathectomy (VATS) for the treatment of palmar hyperhidrosis (PH) is the observed improvement in plantar hyperhidrosis (PLH). Nevertheless, current reports on VATS rarely describe the effect on PLH or just give superficial data. The aim of this study was to prospectively investigate, how surgery affects PLH in patients with PH and PLH over one-year period. Methods From May 2003 to January 2004, 70 consecutive patients with combined PH and PLH underwent VATS at the T2, T3, or T4 ganglion level (47 women and 23 men, with mean age of 23 years). Results Immediately after the operation, all the patients said they were free from PH episodes, except for two patients (2.8%) who suffered from continued PH. Compensatory hyperhidrosis (CH) of various degrees was observed in 58 (90.6%) patients after one year. Only 13 (20.3%) suffered from severe CH. There was a great initial improvement in PLH in 50% of the cases, followed by progressive regression, such that only 23.4% still presented that improvement after one year. The number of cases without overall improvement increased progressively (from 17.1% to 37.5%) and the numbers with slight improvement remained stable (32.9–39.1%). Of the 24 patients with no improvement after one year, 6 patients graded plantar sweating worse. Conclusion Patients with PH and PLH who undergo VATS to treat their PH present a good initial improvement in PLH that reduces to a lower level of improvement after the one-year period.  相似文献   
68.
69.
Ganciclovir (GCV) prophylaxis or pre-emptive therapy significantly reduce the rate of cytomegalovirus (CMV) disease and viremia, but increase the potential for emergence of ganciclovir-resistant CMV strains. The inhibitor concentration at 50% (IC(50)) of GCV from 156 CMV isolates from 59 renal or heart transplant recipients was calculated by means of a rapid phenotypic susceptibility assay. Twenty-seven strains were from 14 patients undergoing GCV therapy. The IC(50) was higher in patients under the prophylaxis regimen. One CMV strain, from a heart transplant recipient, became GCV-resistant after 1 month of therapy (IC(50)=13.7 micromol/l). These data, together with clinical and virological markers, suggested that a switch to foscarnet was necessary, and good evolution was observed. Thus, assay of CMV susceptibility to GCV could be helpful in clinical management.  相似文献   
70.
OBJECTIVE: Kidney transplantation restores renal filtration, although it does not achieve the function of 2 native kidneys, and with time it may involute back to chronic renal failure. We hypothesized that bioelectrical impedance analysis (BIA) might highlight differences for body compartments among kidney transplants (Tx) with different filtration rates. METHODS: Thirty transplantation patients (19 male, 11 female) were studied at 62.4+/-26.6 months postsurgery and were divided into 3 groups: good creatinine clearance (crCl, mL/min/1.73 m2; >65.0), borderline (35.0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