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   7927篇
  免费   548篇
  国内免费   23篇
耳鼻咽喉   76篇
儿科学   196篇
妇产科学   129篇
基础医学   1506篇
口腔科学   391篇
临床医学   753篇
内科学   1335篇
皮肤病学   126篇
神经病学   589篇
特种医学   343篇
外国民族医学   2篇
外科学   978篇
综合类   74篇
一般理论   3篇
预防医学   682篇
眼科学   76篇
药学   579篇
中国医学   10篇
肿瘤学   650篇
  2021年   60篇
  2020年   79篇
  2019年   92篇
  2018年   131篇
  2017年   125篇
  2016年   143篇
  2015年   149篇
  2014年   194篇
  2013年   303篇
  2012年   329篇
  2011年   329篇
  2010年   242篇
  2009年   269篇
  2008年   341篇
  2007年   354篇
  2006年   372篇
  2005年   335篇
  2004年   277篇
  2003年   291篇
  2002年   297篇
  2001年   251篇
  2000年   253篇
  1999年   228篇
  1998年   118篇
  1997年   149篇
  1996年   122篇
  1995年   129篇
  1994年   96篇
  1993年   97篇
  1992年   173篇
  1991年   177篇
  1990年   155篇
  1989年   155篇
  1988年   164篇
  1987年   132篇
  1986年   135篇
  1985年   101篇
  1984年   115篇
  1983年   82篇
  1982年   62篇
  1981年   63篇
  1980年   55篇
  1979年   62篇
  1978年   74篇
  1977年   56篇
  1976年   56篇
  1975年   72篇
  1974年   62篇
  1972年   51篇
  1971年   49篇
排序方式: 共有8498条查询结果,搜索用时 15 毫秒
91.
Five cases of cerebral glioma are presented here that illustrate the benefit of functional CT imaging of blood-brain barrier permeability and cerebral blood volume. Functional CT uses Patlak analysis of a single location dynamic sequence to extract physiological information that is useful clinically in the assessment of cerebral gliomas. Functional CT offers distinct advantages over other functional modalities including clearer delineation of tumour, tumour grading, measurement of tumour activity and monitoring response to therapy.  相似文献   
92.
Zinc-positive neurons and terminals, known to be associated with the glutamatergic projections in the brain, can be demonstrated by the histochemical Timm method and later modifications thereof. The adult rat neocortex contain a uniform lamination of zinc-positive cells with specific projections to, e.g., the striatum. We have previously reported that fetal neocortical grafts implanted in the adult rat neocortex combined with rearing in an enriched environment can improve behavioral functions and reduce the secondary atrophy of thalamus after cortex infarction in adult rats. In order to examine whether the expression of zinc positivity is ontogenetically inherent to neocortical neurons we grafted fetal neocortical tissue to aspiration or ischemic lesions of the frontoparietal neocortex of adult rats, followed by histochemical visualization of the vesicular zinc pool by selenite or sulfide. One further aim of the study was to elucidate to what extent the distribution of zinc-containing neurons and terminals in the grafts depended on rearing under different environmental conditions. The foremost finding of the present study was that the overall density of zinc-containing terminals in fetal cortical transplants placed in brain infarcts of adult spontaneously hypertensive rats is higher when the rats are reared in an enriched environment. Moreover, the presence and expression of zinc-positive neurons and terminals do not seem to be ontogenetically inherent to the cortical neurons as the fetal neocortical grafts placed in aspiration lesions contained no zinc-selenide-positive neurons and few or no zinc-selenide-positive terminals. The presence or expression of zinc-positive cells may thus be induced by ingrowth of fibers and terminals from the host brain as transplants placed in the ischemic lesions expressed both zinc-positive neurons and terminals.  相似文献   
93.
94.
Fifty-two postmenopausal women with newly diagnosed endometrial carcinoma and 58 postmenopausal age-matched controls were studied concerning serum levels of estrone, total estrone, estradiol, androstenedione, testosterone, dehydroepiandrosterone and its sulphate, sex steroid hormone binding globulin, follicle stimulating hormone, and luteinizing hormone. The patients had a higher mean serum level of estradiol (P = 0.006) and a lower level of follicle stimulating hormone (P = 0.001) than the controls and the significant differences remained after the number of years since the menopause and body index had been taken into account. As the serum levels of steroid hormone binding globulin tended to be lower among patients than among controls (P = 0.084), the difference in the biological effect of estradiol between the two groups was probably greater than the difference in serum concentrations would indicate. No significant difference in the ratio of estrone to androstenedione or in the mean serum level of androstenedione was found between patients and controls. These data support the role of estrogen in the etiology of endometrial carcinoma.  相似文献   
95.
People appear to vary in their susceptibility to lifestyle risk factors for cardiometabolic disease; determining a priori who is most sensitive may help optimize the timing, design, and delivery of preventative interventions. We aimed to ascertain a person’s degree of resilience or sensitivity to adverse lifestyle exposures and determine whether these classifications help predict cardiometabolic disease later in life; we pooled data from two population-based Swedish prospective cohort studies (n = 53,507), and we contrasted an individual’s cardiometabolic biomarker profile with the profile predicted for them given their lifestyle exposure characteristics using a quantile random forest approach. People who were classed as ‘sensitive’ to hypertension- and dyslipidemia-related lifestyle exposures were at higher risk of developing cardiovascular disease (CVD, hazards ratio 1.6 (95% CI: 1.3, 1.91)), compared with the general population. No differences were observed for type 2 diabetes (T2D) risk. Here, we report a novel approach to identify individuals who are especially sensitive to adverse lifestyle exposures and who are at higher risk of subsequent cardiovascular events. Early preventive interventions may be needed in this subgroup.  相似文献   
96.
A study in 2000-2001 of causes of death of women of reproductive age (15-49) in the West Bank, Palestinian Occupied Territories, found that 154 of the 411 deceased women aged 15-49 with known marital status were single. Death notification forms for reported deaths were analysed and verbal autopsies carried out, where possible, with relatives of the deceased women. We found important differences in the age at death and causes of death among the single and married women, which can be attributed to the disadvantaged social status of single women in Palestinian society, exacerbated by the current unstable political situation. 41% of the deceased single women were under 25 years of age at death compared to 8% of the married women. The proportion of violent deaths and suicides among the single women was almost twice as high as among the married women, mainly in those below age 25. The single women were also more likely to die from medical conditions which indicated that they faced barriers to accessing health care. The fieldwork was conducted at the height of the Intifada and the Israeli military response, with heavy restrictions on mobility, limiting the possibility of probing deeper into the circumstances surrounding sensitive deaths. More research into the socio-cultural context of single women in Palestine society is needed as a basis for intervention.  相似文献   
97.
98.
<正>To the Editor:Ischemia-reperfusion injury following surgery and transplantation can lead to irreversible multiorgan failure.Intracellular calcium overload is associated to cellular death during ischemiareperfusion.A recently discovered heparin fragment (HF),trisulfated disaccharide (TD),that acts on sodium-calcium exchanger(NCX) decreasing intracellular Ca2+,showed effectiveness on protecting hepatocytes from ischemia-reperfusion injury [1],  相似文献   
99.
OBJECTIVE: To evaluate the influence of the laparoscopic technique in hernia repair regarding time to full recovery and return to work, complications, recurrence rate, and economic aspects. SUMMARY BACKGROUND DATA: Several studies have shown advantages in terms of less pain and faster recovery after laparoscopic hernia repair, whereas others have not, and the cost-effectiveness has been questioned. The laparoscopic technique must be thoroughly compared with the open procedures before its true place in hernia surgery can be defined. METHODS: Six hundred thirteen male patients aged 40 to 75 years were randomized to the conventional procedure, preperitoneal mesh placed by the open technique, or laparoscopic preperitoneal mesh (TAPP). Follow-up was after 7 days, 8 weeks, and 1 year. RESULTS: Of 613 patients undergoing surgery, 604 (98.5%) were followed for 1 year. Patients who underwent TAPP gained full recovery after 18.4 days, compared with 24.2 days for open mesh (p < 0.001) and 26.4 days for the conventional procedure (p < 0.001). Patients who underwent TAPP returned to work after 14.7 days, compared with 17.7 days for open mesh (p = 0.05) and 17.9 days for the conventional procedure (p = 0.04). They also had significantly less restriction in physical activities after 7 days. The TAPP procedure was more expensive, mainly as a result of longer surgical time and equipment costs, even after compensation for earlier return to work. Complications were more common in the TAPP group, with a varying pattern between the groups. Four recurrences in the conventional, 11 in the open mesh, and 4 in the TAPP group were recorded after 1 year (p = n.s.). CONCLUSION: The laparoscopic technique results in both shorter time to full recovery and shorter time to return to work, at the price of substantially increased costs.  相似文献   
100.
Mammography screening is a highly sensitive and specific method to detect breast cancer at an early stage. If screening campaigns are to be cost effective, compliance is valuable. However, many women do not attend when called for mammography screening. Our aim in this study is to understand and explain why women become nonattenders. A sample of 16 nonattending women, aged between 43 and 73 years, participated in this qualitative study, by interviews or written comments. The core category discovered in the data was ``getting no respect.'' The informants did not feel respected from either the society or the health care system. Below this core category, two categories were identified: the mammography examination and affecting circumstances. The performance and its effects comprised the content of the category of mammography examination. The category affecting circumstances included knowledge about risk factors, prevention, and practical or emotional arguments.  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