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   3905篇
  免费   268篇
  国内免费   5篇
耳鼻咽喉   36篇
儿科学   140篇
妇产科学   121篇
基础医学   434篇
口腔科学   68篇
临床医学   286篇
内科学   884篇
皮肤病学   172篇
神经病学   417篇
特种医学   81篇
外科学   514篇
综合类   24篇
一般理论   2篇
预防医学   329篇
眼科学   85篇
药学   223篇
中国医学   4篇
肿瘤学   358篇
  2023年   24篇
  2022年   52篇
  2021年   103篇
  2020年   69篇
  2019年   139篇
  2018年   135篇
  2017年   91篇
  2016年   89篇
  2015年   91篇
  2014年   131篇
  2013年   163篇
  2012年   227篇
  2011年   269篇
  2010年   151篇
  2009年   139篇
  2008年   199篇
  2007年   208篇
  2006年   190篇
  2005年   189篇
  2004年   165篇
  2003年   163篇
  2002年   171篇
  2001年   94篇
  2000年   124篇
  1999年   92篇
  1998年   43篇
  1997年   32篇
  1996年   27篇
  1995年   28篇
  1994年   16篇
  1993年   24篇
  1992年   46篇
  1991年   45篇
  1990年   33篇
  1989年   40篇
  1988年   30篇
  1987年   25篇
  1986年   31篇
  1985年   31篇
  1984年   31篇
  1983年   20篇
  1982年   11篇
  1980年   13篇
  1979年   14篇
  1978年   17篇
  1977年   13篇
  1976年   12篇
  1975年   22篇
  1973年   21篇
  1972年   12篇
排序方式: 共有4178条查询结果,搜索用时 15 毫秒
101.
One year of a very low protein diet (VLPD) can reverse secondary hyperparathyroidism in uremic patients. We studied bone histology, bone mineral density (BMD), and dynamic parathyroid function (calcium/PTH curves) in 16 nondialyzed patients with advanced renal failure who had been receiving a VLPD for a mean of 5 yr (mean protein intake, 0.34 +/- 0.12 mg/kg x day; mean phosphorus intake, 8.2 +/- 2.1 mg/kg x day) and daily supplementation with essential amino acids and their ketoanalogs (1000 IU vitamin D2 and 1-2 g calcium carbonate). Three patients exhibited a high bone formation rate (BFR), 7 patients had normal bone remodeling, and 6 patients had a low BFR, including 2 with osteomalacia and 4 with adynamic bone disease without aluminum overload. A longer diet duration and lower caloric intake were associated with low BFR. More than half of the patients exhibited moderate or severe osteoporosis at the appendicular skeleton. The t score of femur BMD explained 65% of the BFR variance. Patients with a low BFR had a dynamic parathyroid function similar to that of patients with a normal BFR, except they had a lower capacity to buffer a calcium load, whereas patients with a high BFR had a higher basal PTH/maximum PTH and a steeper calcium/PTH curve slope; the calcium set-point was identical in the three groups.  相似文献   
102.
Since the early days of antiretroviral therapy, adherence has emerged as the milestone of success; in fact, it is the most potent predictor of effectiveness. The main factors related to adherence include the complexity of the therapeutic regimen, adverse effects, psychological problems, alcoholism and active addiction to drugs, lack of social and family support and the patient's beliefs and attitudes about the treatment. Adherence monitoring should be part of the HIV patient's regular care, and should be done with feasible, easily applied methods adapted to the different clinical settings. The minimally acceptable measures should include use of a validated questionnaire, together with data from the Pharmacy Department's drug dispensation registry. All patients that begin HAART or undergo a change of treatment should participate in a treatment education program imparted by health professionals with knowledge and experience in the management of patients with HIV infection. The health team (doctors, pharmacists and nursing professionals) should offer maximum availability to solve the doubts and problems that may occur during treatment. When sub-optimal adherence is detected, intervention strategies based on psychological therapy, educational efforts and personal advice should be attempted, in order to adapt the treatment scheme to the patient's habits and provide solutions to the problem of non-compliance. In certain situations, co-morbid conditions will also require attention. Treatment adherence, being a multidimensional problem, needs a multidisciplinary team approach. The choice of therapy, only one aspect of the multidimensional problem of adherence, must be a careful and individualized decision; however, simpler regimens with regard to the number of pills and daily dose are desirable.  相似文献   
103.
Prognostic value of cytokines and neurohormones in severe heart failure   总被引:2,自引:0,他引:2  
BACKGROUND AND OBJECTIVES: The screening of candidates for heart transplantation continues to present difficulties. High plasma levels of cytokines and neurohormones have been associated with a poor prognosis in heart failure but their usefulness for identifying candidates for heart transplantation is still not established. METHODS: In 83 patients (59 11 years old), with systolic left ventricular dysfunction and New York Heart Association functional class III-IV, we assessed levels of aldosterone, atrial natriuretic peptide, plasma renin activity, angiotensin II, norepinephrine, endothelin, interleukin-6 and tumor necrosis factor-alpha. RESULTS: Over the following year, 13 patients died and 26 received heart transplantation. Mean ejection fraction was 23 6%, end-diastolic and end-systolic diameters were 73 10 and 60 10 mm, respectively. Univariate analysis identified the following variables to be associated with poor prognosis: angiotensin II (p = 0.001), norepinephrine (p = 0.003), plasma renin activity (p = 0.02), systolic blood pressure (p = 0.006), end-diastolic diameter (p = 0.02) and end-systolic diameter (p = 0.04). Multivariate regression analysis identified the following variables to be independent predictors of death or need for heart transplantation: a low cardiac index (p = 0.007), plasma angiotensin II (p = 0.001) and pulmonary capillary wedge pressure (p = 0.04) The sensitivity and specificity of angiotensin II for predicting poor outcome was only moderate according to interpretation of the receiver operating curves. CONCLUSIONS: Although plasma angiotensin II was the best neurohormone for identifying patients with severe heart failure and the worst prognosis, its sensitivity and specificity for predicting death or the need for heart transplantation was limited. The decision to transplant should continue to be based on clinical and hemodynamic parameters.  相似文献   
104.
We performed catheter balloon valvuloplasty (CBV) on 8 stenotic operatively-excised bioprosthetic valves (2 Hancock and 6 Ionescu Shiley). Pathology of valves before CBV included degenerative changes: commissural fusion by mounds of calcific deposits (2 valves), fibrotic and focally calcified leaflets (7 valves) and stiff and thick valves (1 valve). Inflation of the balloon resulted in commissural splitting (2 valves), leaflet cracks and fractures (3 valves). Removal of the deflated balloon catheter was associated with debris dislodgement (3 valves). In one case the valve was unable to close with potential for acute regurgitation. Thus, CBV of bioprosthetic valves can split fused commissures by similar mechanisms as in native valves. CBV may fracture calcific deposits causing acute emboli. It can also disrupt the leaflets causing acute insufficiency. The findings suggest a limited role of CBV in the treatment of stenotic bioprosthetic valves in mitral and aortic position.  相似文献   
105.
Aims: To analyze clustering of unhealthy lifestyle behavior and its relationship with non-adherence to recommended clinical preventive care services among Spanish COPD patients. Methods: Cross-sectional study including 2,575 COPD subjects from the 2006 Spanish National Health Survey (NHS) and 2009 European Health Survey for Spain (EHISS). Subjects were asked about the following recommended preventive practices: uptake of blood pressure (BP) measurement, lipid profile, influenza vaccination and dental examination. Lifestyle behaviors included: smoking status, physical activity, alcohol consumption and obesity. Logistic regression models were built to assess the association between clustering of unhealthy lifestyle and the uptake of preventive activities. Results: Blood pressure measurement in the previous 6 months and a blood lipid test in the last year had not been taken by 11.74% and 23.26% of the subjects, respectively, in 2006 NHS and by 11.16% and 16.33% of the subjects, respectively, in EHISS 2009. Then, 36.36% percent had not been vaccinated and 70.61% had not received dental examination in 2006 NHS and these percentages decreased to 27.33% and 66.22%, respectively, in 2009 EHISS. A higher number of unhealthy lifestyle behaviors increased the probability of not being vaccinated and not having a dental examination. Clustering of unhealthy lifestyle behaviors is linearly associated with a greater number of preventive measures unfulfilled. Conclusions: Compliance with healthy lifestyles and adherence to recommended clinical preventive services is under desirable levels among Spanish COPD patients. Patients with lifestyles considered as “worse” are those who also have lower uptake of recommended preventive activities.  相似文献   
106.
107.
108.
Clenbuterol is known to improve competition resistance and muscular growth in athletes. Although it is an illegal drug, its use by farmers is widely spread to induce growth of their cattle. Thus, when clenbuterol is found in the urine of an athlete, there is doubt whether it was consumed with doping purposes or if it is due to the consumption of meat from a clenbuterol‐fed animal. Previous studies suggest that enantiomeric relationship of clenbuterol may be different according to the intake source. However, the enantiomeric relationship throughout a doping cycle or a continuous intake of contaminated meat has not yet been explored. In this first approximation, our aim was the development and validation of a sensitive and rapid method for the determination of S‐ (+) and R‐ (─) clenbuterol enantiomers to be used in a controlled study in rats fed for one week with contaminated meat or simulating a doping cycle. Enantiomers were measured using liquid chromatography coupled to mass spectrometry with a triple quadrupole analyzer (LC‐TQ‐MS) and were separated on an AGP Chiralpak column. The method was fully validated following the VICH (Veterinary International Conference on Harmonization guidelines) and was linear in the range of 12.5–800 pg/mL with a correlation coefficient of ≥0.98 for each enantiomer, and with a limit of quantitation and detection (LOQ and LOD) of 12.5 pg/mL and 6.5 pg/mL, respectively, for both enantiomers. The application of this method pointed out the shift of the enantiomeric relationship in urine from rats during the first five days of the doping cycle compared to those fed with contaminated meat. This finding can be of substantial importance in further doping studies.  相似文献   
109.
110.
Dengue virus infections are a major cause of morbidity in tropical countries. Early detection of dengue hemorrhagic fever (DHF) may help identify individuals that would benefit from intensive therapy. Predictive modeling was performed using 11 laboratory values of 51 individuals (38 DF and 13 DHF) obtained on initial presentation using logistic regression. We produced a robust model with an area under the curve of 0.9615 that retained IL-10 levels, platelets, and lymphocytes as the major predictive features. A classification and regression tree was developed on these features that were 86% accurate on cross-validation. The IL-10 levels and platelet counts were also identified as the most informative features associated with DHF using a Random Forest classifier. In the presence of polymerase chain reaction-proven acute dengue infections, we suggest a complete blood count and rapid measurement of IL-10 can assist in the triage of potential DHF cases for close follow-up or clinical intervention improving clinical outcome.  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