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   63534篇
  免费   6773篇
  国内免费   1864篇
耳鼻咽喉   434篇
儿科学   1564篇
妇产科学   1439篇
基础医学   4441篇
口腔科学   1527篇
临床医学   7149篇
内科学   10606篇
皮肤病学   781篇
神经病学   4043篇
特种医学   1012篇
外国民族医学   7篇
外科学   6079篇
综合类   9993篇
现状与发展   8篇
一般理论   1篇
预防医学   10723篇
眼科学   1109篇
药学   4255篇
  48篇
中国医学   1627篇
肿瘤学   5325篇
  2024年   216篇
  2023年   1199篇
  2022年   2456篇
  2021年   3436篇
  2020年   3314篇
  2019年   2430篇
  2018年   2435篇
  2017年   2489篇
  2016年   2806篇
  2015年   2574篇
  2014年   4870篇
  2013年   5274篇
  2012年   4428篇
  2011年   4491篇
  2010年   3469篇
  2009年   3143篇
  2008年   3018篇
  2007年   2945篇
  2006年   2562篇
  2005年   2194篇
  2004年   1765篇
  2003年   1529篇
  2002年   1283篇
  2001年   1119篇
  2000年   918篇
  1999年   745篇
  1998年   657篇
  1997年   595篇
  1996年   466篇
  1995年   431篇
  1994年   402篇
  1993年   308篇
  1992年   314篇
  1991年   290篇
  1990年   224篇
  1989年   197篇
  1988年   178篇
  1987年   134篇
  1986年   127篇
  1985年   143篇
  1984年   125篇
  1983年   74篇
  1982年   89篇
  1981年   68篇
  1980年   55篇
  1979年   48篇
  1978年   30篇
  1977年   24篇
  1976年   36篇
  1975年   20篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
102.
At our center, since 1982, a body mass index (BMI) of less than 30 has been a prerequisite for placing a patient on the waiting list for renal transplantation. This decision was made because obese transplant recipients seemed to have a less than favorable post-transplant outcome. The aim of this study was to evaluate whether this requirement is still justified. Forty-six patients with a BMI above 30 underwent primary cadaveric renal transplantation between 1972 and 1993. For each of these obese patients, five consecutive non-obese (BMI 20–25) control patients were selected. Patient and graft survival, causes of graft loss, and acute rejection rate were evaluated for the two patient groups before and after the year 1982. Within the first 30 post-transplant days, one patient (2 %) and 11 grafts (24 %) were lost in the group of obese patients whereas seven patients (3 %) and 36 grafts (16 %) were lost in the control group. Among the obese patients, renal circulatory complications were a major cause of graft loss. In the period 1973–1981, the 1-year patient survival rate was 65 % among obese patients versus 75 % among controls from 1982 to 1993, this was 90 % versus 93 %. From 1973 to 1981, the 1-year graft survival rate was 25 % among obese patients versus 53 % among controls (P < 0.05); from 1982 to 1993, it was 68 % versus 84 % (P = NS). Multivariate analysis showed that the immunosuppressive regimen, age of the patient, BMI, and cold ischemia time of the graft had a significant influence on graft survival. The acute rejection rate within the first 30 days was 28 % among obese patients and 35 % among controls (P = NS). We conclude that a BMI below or equal to 30 is still justified as a prerequisite for placement on the waiting list for renal transplantation, for despite an overall improvement, the outcome of renal transplantation in obese patients remains worse than that in non-obese patients. Received: 3 February 1997 Received after revision: 4 April 1997 Accepted: 8 April 1997  相似文献   
103.
A comparison of 121 mature-age and 270 normal-age entrants who graduated from the University of Queensland Medical School between 1972 and 1987 shows that mature-age entrants are some 7 years older, are more likely to come from public (state) schools and less likely to have parents in professional/technical occupations. Otherwise, the two groups were similar in terms of gender, marital status, number of children, ethnic background and current practice location. The educational background of mature-age entrants prior to admission includes 44.6% with degrees in health-science areas and 31.4% with degrees in non-health areas. Reasons for delayed entry of mature-age entrants include late consideration of medicine as a career (34.7%), financial problems (31.4%), dissatisfaction with previous career (30.6%), poor academic results (19.8%), or a combination of the above factors. Motivations to study medicine include family influences (more so in normal-age entrants), altruistic reasons (more so in mature-age entrants) and a variety of personal/social factors such as intellectual satisfaction, prestige and financial security (similar for both groups) and parental expectations (more so in normal-age entrants). Mature-age entrants experienced greater stress throughout the medical course, especially with regard to financial difficulties, loneliness/isolation from the students and family problems (a greater proportion were married with children). While whole-course grades were similar in both groups, normal-age entrants tended to win more undergraduate honours/prizes and postgraduate diplomas/degrees, including specialist qualifications. Practice settings were similar in terms of group private practice, hospital/clinic practice or medical administration, but there was a greater proportion of mature-age entrants in solo private practice, and a smaller proportion in teaching/research. If given the time over, some two-thirds of both groups would choose medicine as a career. Reasons for job satisfaction include helping patients, intellectual stimulation and financial rewards. Reasons for dissatisfaction include pressure of work, red-tape/paperwork, 'doctor-bashing', long working hours, emotional strain, financial pressure, unfulfilled career expectations and irritation with trivial medical complaints.  相似文献   
104.
The influence of metabolic control (HbA1c), noradrenaline (NA) and insulin-like growth factors (IGF-I and IGF-II) on renal function and size was investigated in 11 insulin-dependent diabetes mellitus patients aged 11–17 years. Renal function was evaluated in terms of glomerular filtration rate (GFR) and effective renal plasma flow (ERPF). Renal size was determined as renal parenchymal volume (RPV) by ultrasonography. The patients' HbA1c values ranged from 8.2% to 12.9% (normal range 5.5–8.5%) and their GFR and ERPF were higher than normal. Their IGF-II values were higher, and NA and IGF-I levels were lower than those of healthy controls. Inverse correlations between NA and GFR (r=–0.66) and NA and ERPF (r=–0.63) were found. No correlation was found between serum IGF-I and renal functional parameters. The IGF-II values correlated with GFR and HbA1c (r=0.63,r=0.70 respectively). There were linear correlations between RPV and GFR, RPV and ERPF, HbA1c and GFR, and ERPF and RPV. Decreased NA concentrations and increased IGF-II values appear to be factors contributing to renal hyperfunction in these patients.  相似文献   
105.
呼吸道感染是呼吸系统常见病、多发病。利用杭州地区1990年1月~1992年12月气象资料作了统计分析,并对同期来海军杭州疗养院门诊就诊的呼吸道感染病人进行了调查。结果为1~3、11、12月发病率高,与5~9月相比有非常显著差异(P<0.001),呼吸道感染与气温低,湿度高,温差大,天气骤变等气象因素密切相关。潮冷天气(气温在10℃以下),频繁降温(每月3次以上),大幅度降温(4℃以上)三种气象因素共同存在情况下可导致呼吸道感染性疾病的高发。同时从气象学角度提出了预防该病的一些措施。  相似文献   
106.
Summary In a cross-sectional study of 181 male workers of a rotogravure printing plant, most of whom were exposed to toluene levels well above the GDR threshold limit values, 55 subjects revealed pathological liver screening values (activities of serum aspartate aminotransferase, alanine amino-transferase, gamma glutamyltransferase; liver size). The differential diagnostic examination showed in 51 out of these 55 subjects an association with competing factors such as alcohol abuse (78%) and overweight (40%), to a slight extent disorders of fat and carbohydrate metabolism and of the gallbladder. Drug intake did not play any role. The variance and regression analyses of the biochemical data have shown that alcohol significantly and considerably increases the activities of all three enzymes tested. Bodyweight had a similar, but less pronounced, significant effect. On the other hand, in subjects with a higher alcohol intake the activities of liver enzymes in highly toluene exposed subgroups were significantly and clearly lower than among slightly toluene exposed workers.  相似文献   
107.
家禽加工流水线作业工人颈肩腕疾患的调查   总被引:1,自引:0,他引:1  
对149名家禽加工厂作业女工的颈肩腕疾患进行了调查。结果表明:观察组职业性颈肩腕疾患OCD,(肩周炎、尺管综合征、腕管综合征、腱鞘炎、肱骨内外髁炎)的总发生率为39.60%,与对照组相比差异有非常显著意义(P<0.01),其发生率与工龄、年龄及工种别有关。我们认为OCD发生的职业危险因素主要是上肢反复用力活动、静力作业、不合理的操作姿势,而且低温、高温的作业环境对OCD的发生也起到一定的促进作用。  相似文献   
108.
化工行业职业性机械伤害危险因素的病例-交叉方法研究   总被引:6,自引:0,他引:6  
目的 研究化工行业机械伤害的有关诱发因素,估计其作用强度。方法 采用病例-交叉设计的方法。以操作和检修时受伤的化工工人为研究对象,每个对象在受伤后2d内完成调查,收集他们受伤前10min、上一工作日同一段时间和受伤前1周内有关诱发因素暴露的信息,用配对时间段方法和一般频数法进行分析,评估各种诱发因素的危险度。结果 一般频数法分析的结构表明,操作方法异常、设备工具缺陷、工作紧迫、注意力不集中、不使用防护用品、精神状况较差、与同事配合不协调、工作环境发生变化等瞬时危害因素的RR值及95%可信限的下限均大于1。配对时间段方法分析的结果与其相拟,但95%可信限较宽。结论 化工行业职业性机械伤害的发生存在着诸多诱发因素。病例-交叉研究中的一般频数法与配对时间段方法相比,前者所得结果较为可靠,研究的相对效率较高。建议进一步使用多个时间段方法进行研究,以减小混杂因素的影响。  相似文献   
109.
The relative importance of vitamin D deficiency, secondary hyperparathyroidism, nutritional deficiency and low bone mineral density (BMD) as risk factors for hip fracture is not definitely established. In the framework of a case-control study of risk factors for hip fractured, biochemical markers of bone metabolism and nutrition and femoral BMD data were compared in 136 female and 43 male hip fracture patients, 126 female and 44 male age-matched hospitalized controls, and 47 healthy elderly women (8 men). Patients with hip fracture had lower albumin (−10%9 and 25(OH)-vitamin D (25(OH)D; −19%) compared with hospitalized controls, and lower albumin (−28%) and 25(OH)D levels (−52%) compared with the elderly controls. Serum values of IGFBP-3 were also significantly lower (−33%) in hip fracture patients than in community controls. BMD of femoral neck was lower (p < 0.001) in patients than in hospitalized and community controls. In hip fracture patients, parathyroid hormone (PTH) correlated weakly with BMD (neck: r = −0.19, trochanter: r = −0.17; both p < 0.05). When all women were pooled (n = 233), albumin correlated significantly (age-adjusted) with BMD at all sites (neck: r = 0.27, trochanter: r = 0.25; all p < 0.001). Albumin, but not 25(OH)D, also correlated with skinfold thickness (r = 0.19, p < 0.0025) and with body mass index (BMI) (r = 0.14, p < 0.05). Male patients with hip fracture had lower BMD and albumin (both p < 0.001), 25(OH)D (p = 0.02) and IGFBP-3 levels (p <: 0.005) compared with the controls. When male patients and controls were pooled together, albumin, skinfold thickness and BMI were significantly correlated with each other, but not with BMD. IGFBP-3 was highly correlated with albumin (p < 0.0001), 25(OH)D (p < 0.005) and, less significantly, with PTH (p < 0.05), but not with BMI or skinfold thickness. IGFBP-3 was significantly correlated with BMD at all sites (neck: r = 0.27, p < 0.05); trochanter: r = 0.40, p < 0.0005). In conclusion, low albumin and low BMD were both important risk factors for hip fracture. Low serum albumin was the strongest independent variable correlated with hip fractures. In men, IGFBP-3 was correlated with BMD. The femoral BMD depended only weakly on PTH and 25(OH)D, but was correlated at all sites with albumin, a non-specific parameter of nutrition and general health.  相似文献   
110.
This study investigated the relationship of protective factors (PF) to adult adaptation in a nonclinical sample consisting of 264 undergraduate women: two groups without childhood sexual abuse (CSA), high (n = 109) and low (n = 99) on PF; and two groups with CSA, high (n = 17) and low (n = 27) on PF. The first hypothesis that higher levels of PF would be significantly associated with higher levels of functioning for all individuals was supported by the data. The second hypothesis that the women with CSA and higher levels of PF would appear similar in adaptation to those without CSA was also supported. The findings further suggest that though the protective factors were beneficial for most individuals, they were significantly more helpful for those with CSA.  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