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   90691篇
  免费   9165篇
  国内免费   570篇
耳鼻咽喉   263篇
儿科学   1993篇
妇产科学   1703篇
基础医学   5620篇
口腔科学   4372篇
临床医学   16326篇
内科学   7876篇
皮肤病学   807篇
神经病学   4985篇
特种医学   882篇
外科学   3356篇
综合类   8341篇
现状与发展   3篇
一般理论   91篇
预防医学   37359篇
眼科学   338篇
药学   3126篇
  80篇
中国医学   861篇
肿瘤学   2044篇
  2024年   347篇
  2023年   2772篇
  2022年   3630篇
  2021年   5011篇
  2020年   5065篇
  2019年   4842篇
  2018年   4215篇
  2017年   4022篇
  2016年   3858篇
  2015年   3779篇
  2014年   5922篇
  2013年   7916篇
  2012年   5158篇
  2011年   5635篇
  2010年   4193篇
  2009年   4362篇
  2008年   4200篇
  2007年   4239篇
  2006年   3611篇
  2005年   2796篇
  2004年   2431篇
  2003年   2067篇
  2002年   1560篇
  2001年   1515篇
  2000年   1300篇
  1999年   912篇
  1998年   787篇
  1997年   644篇
  1996年   547篇
  1995年   368篇
  1994年   371篇
  1993年   361篇
  1992年   301篇
  1991年   237篇
  1990年   199篇
  1989年   164篇
  1988年   205篇
  1987年   127篇
  1986年   119篇
  1985年   120篇
  1984年   91篇
  1983年   56篇
  1982年   52篇
  1981年   45篇
  1980年   62篇
  1979年   33篇
  1978年   39篇
  1977年   38篇
  1976年   34篇
  1975年   34篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
An historical prospective study of mortality within a cohort of 1,410 gas distribution workers was conducted. This cohort was followed for ten years (1971-1980) and data on 118 deaths were obtained. Five-year (1973-1977) averages of both St. Louis and United States age-specific mortality figures were used to create "expected" mortality rates for comparison with the observed deaths in the cohort. Analyses of the cohort were done according to: 1) person-years contributed during the study period (the "age-attained" method) and 2) the number of years from commencement of work in the company until the end of the study period (1980) or death (the "latency" methods of analysis, Standardized Mortality Ratios (SMRs) were calculated for all causes of death, all malignant neoplasms, and for cardiovascular disease and malignant neoplasms of the respiratory and digestive systems. In no case was the SMR found to be beyond the range of what would be expected in the "standard" populations. While the present study does not contradict the negative findings of the one previous investigation of mortality of gas distribution workers, the limitations of small cohort size, reliance on death certificates and non-industrial comparison populations make any conclusions at best provisional.  相似文献   
992.
Workers in pulpmills can be exposed to a multitude of gases hazardous to respiratory function, the most common of which is chlorine gas. First-aid reports of acute gas overexposure incidents ("gassings") over an 8 year period were used to generate exposure data on a group of pulpmill workers whose respiratory function had been studied cross-sectionally in 1981 and 1988. Three hundred forty-eight incidents representing 174 workers were identified, 78% of these being treated solely by the first-aid attendant with the administration of O2 and cough suppression medication. Among 316 workers tested during a 1988 respiratory health survey, 78 had at least one chlorine or chlorine dioxide "gassing" incident. There was a significant decrease in the FEV1/FVC ratio (p less than .05) as well as increased risk for workplace associated chest symptoms in this group with at least one "gassing" incident. In an age- and smoking-matched analysis, among workers tested both in 1981 and 1988, there was a greater decline in FEV2/FVC ratio and MMF (p less than .05) in the "gassed" group than in the nonexposed group over the 7 year period of observation. These results emphasize the need for worker protection against accidental chlorine gas exposures.  相似文献   
993.
Data from 17 countries across 28 years are used to estimate an international health expenditure function based on real per capita GNP. Actual and expected spending levels are compared for 24 countries. Between 1960 and 1987, it has been rare for health expenditure in any country to be more than +/- 20 per cent from the projected value. The norm is for spending to rise at 1.5 times the growth rate of GDP. Two countries appear to display significant anomalies. Spending in the United Kingdom is consistently 15-25 per cent below normal for all years, and Danish expenditure has declined from 7 to 6 per cent of GDP since 1975.  相似文献   
994.
Financing national health insurance is a topic that has been discussed for a long time in the United States. It is also of relevance for less developed countries, in particular in the Far East where some countries have just introduced or are on the brink of introducing national health insurance. Furthermore, there is an urgent need to consult those former socialist countries wishing to introduce a national health insurance system. The paper deals with basic principles of health insurance and specific elements of a (compulsory) social health insurance in detail.  相似文献   
995.
The authors developed a union sponsored 2-day human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS) "train the trainer" program for healthcare workers in the San Francisco Bay Area. The program incorporated the "education for action" approach in an effort to respond to the inadequacies in many traditional, institutional trainings. Service Employees International Union (SEIU) and Labor Occupational Health Program (LOHP) conducted the HIV/AIDS "train the trainer" program for approximately 100 healthcare workers in county public hospitals and community health clinics. After completing the program, these workers went back to their healthcare facilities, or community organizations, and led additional classes on HIV/AIDS transmission and prevention for approximately 600 more people. The goal of the program was to empower healthcare workers to: 1) identify the occupational risks associated with exposure to blood and potentially infectious body fluids at the workplace; 2) develop strategies to reduce those risks; 3) discuss their feelings about caring for an HIV/AIDS patient; and, 4) conduct HIV/AIDS workshops at the workplace.  相似文献   
996.
Summary The occupational exposure to cyclophosphamide (CP), ifosfamide (IF), 5-fluorouracil (5FU), and methotrexate (MTX) of 25 pharmacy technicians and nurses from four departments of a hospital was investigated. Previously developed methods for the detection of exposure to some antineoplastic agents were validated. Exposure to CP, IF, 5FU, and MTX was measured by the analysis of these compounds in the environment (air samples and wipe samples from possible contaminated surfaces and objects). Contamination of the work environment was found not only on the working trays of the hoods and on the floors of the different rooms but also on other objects like tables, the sink unit, cleaned urinals and chamber pots, and drug vials and ampules used for preparation and packing of drugs. The gloves used during preparation of the drugs and during cleaning of the hoods were always contaminated. The uptake of CP or IF was determined by the analysis of both compounds in urine. CP or IF was detected in the urine of eight pharmacy technicians and nurses. The amounts ranged from < 0.01 to 0.5 g (median: 0.1 g). CP and IF were found not only in the urine of pharmacy technicians and nurses actively handling these compounds (n = 2) but also in the urine of pharmacy technicians and nurses not directly involved in the preparation and administration of these two drugs (n = 6). CP and IF were excreted during different periods ranging from 1.40 to 24.15 h after the beginning of the working day, suggesting different times of exposure, different exposure routes, and/or interindividual differences in biotransformation and excretion rate for these compounds. The urinary CP and IF determination method seems to be sensitive and suitable for monitoring the exposure to and measuring the uptake of these toxic compounds by pharmacy technicians and nurses during occupational activities.  相似文献   
997.
Summary Currently there are no limitations on age of employment on private forestries in Japan. Hence, it was hypothesized that in these kind of enterprises, elderly chain saw operators, or those with long-term exposure, might be at higher risk of developing hand-arm vibration syndrome (HAVS). We consequently investigated the prevalence of HAVS in 447 chain saw workers on private forestries in Gifu Prefecture, Japan, with particular reference to age and exposure period. Of this population, 43 (9.6%) had signs and symptoms of vibration-induced white finger (VWF), and among these workers the severity of finger blanching was significantly correlated (P < 0.01) with the exposure period. Classification of all subjects by exposure period showed that workers with 30 years' exposure had higher prevalences of VWF (20.9%) and numbness of the hands (25.4%) compared to other groups. Significant differences (P < 0.01) were found between the functional capacities of workers with VWF and those of control subjects. We concluded that (a) the elderly chain saw operators and those with longer exposure should be moved to other jobs with a lower or no risk of exposure to vibration, and (b) the results of screening tests, even without cold water immersion (which we did not employ, in order to protect workers' hands), could be helpful for the identification of workers with VWF.  相似文献   
998.
Summary No difference was found between the nerve conduction velocities of the ulnar nerve of 32 lead exposed workers in the mill of a lead-zinc mine, compared to that of a control group of 14 persons. The lead exposure period was 2–37 months (mean: 12.9 months).The blood lead of the exposed group was as an average (± SD): 53 ± 16 g per 100 ml compared to 11 ± 4 g per 100 ml for the control group.Further studies are needed to establish a possible dose-time-response relationship for the possible, subclinical neuropathy found by some investigators.  相似文献   
999.
Researchers from Japan, China and Singapore have initiated a collaborative project, with the aim of comparing adolescent quality of life (QOL) internationally. This study presents the primary results of the investigation conducted in Beijing, China, and Kobe, Japan. The 70-item Quality of Life Questionnaire for Adolescents (QOLQA) was developed and evaluated in Japan and China. In total, 1114 Japanese and 613 Chinese junior high school students, aged 12-15 years, completed the questionnaire. Chinese students scored significantly higher than the Japanese students in overall QOL scores and in most domains. For both groups, subjects had highest score in the independence domain and lowest in psychological domain. In terms of overall QOL score, Chinese male students ranked first, followed by Chinese girls, Japanese boys, and Japanese girls. In the Japanese group, a continuing decrease of QOL scores with age was observed without exception, but no such tendency was present in their Chinese counterparts. No parallel relationship was observed between the higher level of economic development and better quality of life. The results also suggest that mental health promotion should be a priority in improving overall quality of life of adolescents both in Japan and China.  相似文献   
1000.
There is a possibility that cessation of smoking improves mental health, but there are no studies that have demonstrated this. A cohort study was performed for 1 year in 18 males who spontaneously stopped smoking (cessation group) and 173 who continued to smoke (smoking group). The mental health state was evaluated using the Japanese version of the 30-item General Health Questionnaire (GHQ-30) before the cessation of smoking and 6 months and 1 year after smoking cessation. Changes in the GHQ score were compared between the cessation and smoking groups. In order to control the effects of confounding factors, multiple regression analyses were performed using the GHQ score after 6 months and 1 year as dependent variables. The GHQ score in the cessation group significantly decreased 6 months and 1 year after smoking cessation (P < 0.04 and 0.01, respectively, by paired t-test). In the smoking group, the GHQ score slightly decreased. Repeated measure analysis of variance revealed that the decrease in the GHQ score in the cessation group was significantly larger than in the smoking group. Multiple regression analysis revealed significant effects of smoking cessation on mental health after controlling for other confounding factors. It can be concluded that smoking cessation may improve mental health.  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