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   8511篇
  免费   943篇
  国内免费   12篇
耳鼻咽喉   78篇
儿科学   270篇
妇产科学   186篇
基础医学   1189篇
口腔科学   275篇
临床医学   950篇
内科学   1607篇
皮肤病学   94篇
神经病学   892篇
特种医学   257篇
外科学   1169篇
综合类   318篇
一般理论   7篇
预防医学   975篇
眼科学   270篇
药学   521篇
中国医学   2篇
肿瘤学   406篇
  2021年   130篇
  2020年   105篇
  2019年   148篇
  2018年   152篇
  2017年   131篇
  2016年   109篇
  2015年   132篇
  2014年   181篇
  2013年   320篇
  2012年   397篇
  2011年   417篇
  2010年   221篇
  2009年   212篇
  2008年   367篇
  2007年   383篇
  2006年   382篇
  2005年   366篇
  2004年   353篇
  2003年   275篇
  2002年   306篇
  2001年   281篇
  2000年   280篇
  1999年   254篇
  1998年   90篇
  1997年   86篇
  1996年   88篇
  1995年   76篇
  1994年   75篇
  1993年   71篇
  1992年   205篇
  1991年   180篇
  1990年   204篇
  1989年   200篇
  1988年   189篇
  1987年   147篇
  1986年   150篇
  1985年   160篇
  1984年   113篇
  1983年   110篇
  1982年   76篇
  1981年   60篇
  1979年   115篇
  1978年   96篇
  1977年   78篇
  1976年   65篇
  1975年   60篇
  1974年   71篇
  1973年   95篇
  1972年   87篇
  1971年   75篇
排序方式: 共有9466条查询结果,搜索用时 15 毫秒
991.
Government policy promoting consumerism in healthcare can be seen as offering up certain preferred identities to which its citizens are encouraged to aspire. Whilst many commentators reject the notion that health services users should be conceived of as consumers, this paper outlines the relevance of the concept to our understanding of the ways in which individuals manage their health and service use. The paper examines the identity work undertaken by individuals in relation to decisions about healthcare preferences and assesses the extent to which this is compatible with the identities promoted in Government policy. We suggest that in circumstances where individuals feel both a sense of personal entitlement and a desire to be supportive of the needs of other members of the community, 'doing' ethical consumer can be fraught with discomfort and anxiety. These anxieties are exacerbated in a context where citizenship is increasingly being defined in terms of consumer identities, and making good (health) choices might be seen as distinguishing the civilised from the marginalised.  相似文献   
992.
A health education program was evaluated which used child development specialists as home visitors and served a population of first-time mothers living in rural communities. The evaluation compared health and safety outcomes between intervention and control groups. The research staff, separate from the intervention staff, collected data in the homes of 156 intervention and 107 control mothers when the infants were 6 and 12 months old. Significant group differences were found on health and safety outcomes. As compared with controls, the intervention mothers (i) had safer homes; (ii) were more likely to use birth control, thus had fewer pregnancies since birth of their first child; (iii) reported smoking fewer cigarettes; (iv) knew more about effects of smoking on their child's health and (v) were more likely to use health department services. In sum, mothers who received early education home visits from child development specialists experienced positive health and safety outcomes. It is highly recommended that a program such as this be implemented as part of health delivery program with new mothers and infants.  相似文献   
993.
994.
Accurate detection of incident hepatitis C virus (HCV) infection is required to target and evaluate public health interventions, but acute infection is largely asymptomatic and difficult to detect using traditional methods. Our aim was to evaluate a previously developed HCV avidity assay to distinguish acute from chronic HCV infection. Plasma samples collected from recent seroconversion subjects in two large Australian cohorts were tested using the avidity assay, and the avidity index (AI) was calculated. Demographic and clinical characteristics of patients with low/high AI were compared via logistic regression. Sensitivity and specificity of the assay for recent infection and the mean duration of recent infection (MDRI) were estimated stratified by HCV genotype. Avidity was assessed in 567 samples (from 215 participants), including 304 with viraemia (defined as ≥250 IU/mL). An inverse relationship between AI and infection duration was found in viraemic samples only. The adjusted odds of a low AI (<30%) decreased with infection duration (odds ratio [OR] per week of 0.93; 95% CI:0.89‐0.97), and were lower for G1 compared with G3 samples (OR = 0.14; 95% CI:0.05‐0.39). Defining recent infection as <26 weeks, sensitivity (at AI cut‐off of 20%) was estimated at 48% (95% CI:39‐56%), 36% (95% CI:20‐52%), and 65% (95% CI:54‐75%) and MDRI was 116, 83, and 152 days for all genotypes, G1, and G3, respectively. Specificity (≥52 weeks infection duration, all genotypes) was 96% (95% CI:90‐98%). HCV avidity testing has utility for detecting recent HCV infection in patients, and for assessing progress in reaching incidence targets for eliminating transmission, but variation in assay performance across genotype should be recognized.  相似文献   
995.
McDonald DD  Molony SL 《Western journal of nursing research》2004,26(8):836-52; discussion 853-9
This study tested the effect of a preoperative pain communication intervention on older adults' ability to obtain pain relief after a total knee arthroplasty. A posttest-only experimental design was used to compare older adults randomly assigned to (a) view a pain management and pain communication film, (b) view the pain management film only, or (c) receive standard care only. Initial method adjustments decreased potential error in the study. Adjustments included testing only total knee arthroplasty patients receiving standard physical therapy and omitting unreliable measures from the analyses. Recruitment of the standard care group was halted when differences emerged between the remaining groups. Older adults in the communication group reported significantly less sensory pain on postoperative Day 1 than older adults in the pain management only group. Teaching older adults both pain communication skills and pain management information before surgery might result in greater pain relief during the early postoperative period.  相似文献   
996.
Endothelial attachment is the initial step in leukocyte recruitment into developing atherosclerotic lesions. To determine whether vascular cell adhesion molecule-1 (VCAM-1) expression may play a role in inflammatory cell recruitment into human atherosclerotic lesions, immunohistochemistry was performed with a polyclonal rabbit antisera, raised against recombinant human VCAM-1, on 24 atherosclerotic coronary plaques and 11 control coronary segments with nonatherosclerotic diffuse intimal thickening from 10 patients. Immunophenotyping was performed on adjacent sections to identify smooth muscle cells, macrophages, and endothelial cells. To confirm VCAM-1-expressing cell types, double immunostaining with VCAM-1 antisera and each of the cell-specific markers and in situ hybridization were performed. All atherosclerotic plaques contained some VCAM-1, compared to 45% of control segments. VCAM-1 was found infrequently on endothelial cells at the arterial lumen din both plaques (21%) and in control segments (27%), but was prevalent in areas of neovascularization and inflammatory infiltrate in the base of plaques. Double immunostaining and in situ hybridization confirmed that most VCAM-1 was expressed by subsets of plaque smooth muscle cells and macrophages. The results document the presence of VCAM-1 in human atherosclerosis, demonstrate VCAM-1 expression by human smooth muscle cells in vivo, and suggest that intimal neovasculature may be an important site of inflammatory cell recruitment into advanced coronary lesions.  相似文献   
997.
Human interleukin (IL) 1 receptor–associated kinase 4 (IRAK-4) deficiency is a recently discovered primary immunodeficiency that impairs Toll/IL-1R immunity, except for the Toll-like receptor (TLR) 3– and TLR4–interferon (IFN)-a/b pathways. The clinical and immunological phenotype remains largely unknown. We diagnosed up to 28 patients with IRAK-4 deficiency, tested blood TLR responses for individual leukocyte subsets, and TLR responses for multiple cytokines. The patients' peripheral blood mononuclear cells (PBMCs) did not induce the 11 non-IFN cytokines tested upon activation with TLR agonists other than the nonspecific TLR3 agonist poly(I:C). The patients' individual cell subsets from both myeloid (granulocytes, monocytes, monocyte-derived dendritic cells [MDDCs], myeloid DCs [MDCs], and plasmacytoid DCs) and lymphoid (B, T, and NK cells) lineages did not respond to the TLR agonists that stimulated control cells, with the exception of residual responses to poly(I:C) and lipopolysaccharide in MDCs and MDDCs. Most patients (22 out of 28; 79%) suffered from invasive pneumococcal disease, which was often recurrent (13 out of 22; 59%). Other infections were rare, with the exception of severe staphylococcal disease (9 out of 28; 32%). Almost half of the patients died (12 out of 28; 43%). No death and no invasive infection occurred in patients older than 8 and 14 yr, respectively. The IRAK-4–dependent TLRs and IL-1Rs are therefore vital for childhood immunity to pyogenic bacteria, particularly Streptococcus pneumoniae. Conversely, IRAK-4–dependent human TLRs appear to play a redundant role in protective immunity to most infections, at most limited to childhood immunity to some pyogenic bacteria.  相似文献   
998.
999.
The influence of testosterone on gonadotropin-releasing hormone (GnRH) secretion was assessed indirectly by altering the serum testosterone concentration of male rats and measuring GnRH release from their incubated hypothalami 1 wk later.GnRH release from hypothalami of castrated rats was 13.4+/-1.2 (SE) pg/h, compared to 35.3+/-3.8 pg/h from hypothalami of intact rats (P < 0.001). GnRH release from the hypothalami of castrated rats treated with testosterone propionate, 100 or 500 mug daily, was 25.0+/-3.4 pg/h and 27.9+/-3.6 pg/h, which is significantly greater (P < 0.05 and P < 0.01, respectively) than that from hypothalami of castrated rats treated only with sesame oil.A similar decrease in GnRH release from hypothalami of hypophysectomized rats and prevention of this decrease by treating the hypophysectomized rats with testosterone propionate is evidence that the observed effects of testosterone are not mediated via luteinizing hormone and(or) follicle-stimulating hormone secretion. Treatment of castrated rats with either dihydrotestosterone propionate or estradiol benzoate also prevented the decrease in GnRH release from the hypothalami of castrated rats.We conclude that testosterone, dihydrotestosterone, and estradiol all prevent the decrease in GnRH release from hypothalami of castrated rats treated with these steroids. The possibility exists that these steroids may also maintain GnRH secretion in vivo.  相似文献   
1000.
The ability of d,l-propranolol to block renin secretion in response to various extrarenal stimuli, such as hemorrhage and hypoglycemia, has been interpreted to indicate the presence of an intrarenal beta receptor regulating renin release. However, two problems complicate this interpretation: (a) the stimuli have effects outside the kidney, and (b) d,l-propranolol has a local anesthetic, as well as a beta adrenergic blocking, action. In the present study, the effects of a purely intrarenal stimulus, in the form of renal nerve stimulation (RNS), on renin secretion was examined. The effects of d,l-propranolol (anesthetic and beta-blocking activity), l-propranolol (beta-blocking activity only), and d-propranolol (local anesthetic activity only) on the renin response to RNS were examined. In a control group of animals, two sequential RNS increased mean renin secretion from 401 to 1,255 U/min (P less than 0.25) and from 220 to 2,179 U/min (P less than 0.01). In a second group the first RNS increased renin secretion from 201 to 1,181 U/min (P less than 0.01), but after d,l-propranolol was given RNS did not significantly alter renin secretion (33 to 55 U/min). In a third group the initial RNS increased renin secretion from 378 to 1,802 U/min (P less than 0.025), but after l-propranolol was given RNS had no significant effect on renin secretion (84 to 51 U/min). A fourth group of dogs showed a rise in renin secretion from 205 to 880 U/min (P less than 0.001) in response to the first RNS, while the second RNS, given after an infusion of d-propranolol, caused a rise in renin secretion from 80 to 482 (P less than 0.005). The nature of the electrical stimulus was consistent in all groups and caused no detectable changes in renal or systemic hemodynamics or in urinary electrolyte excretion. The results, therefore, indicate that renin secretion can be stimulated through intrarenal beta receptors independent of changes in systemic or renal hemodynamics or in tubular sodium reabsorption. Hence the effect of beta stimulation on renin secretion would appear to result from a direct action on the renin-secreting cells of the juxtaglomerular apparatus.  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