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   3258篇
  免费   147篇
  国内免费   17篇
耳鼻咽喉   35篇
儿科学   30篇
妇产科学   32篇
基础医学   375篇
口腔科学   41篇
临床医学   302篇
内科学   649篇
皮肤病学   45篇
神经病学   489篇
特种医学   106篇
外科学   674篇
综合类   31篇
预防医学   142篇
眼科学   34篇
药学   228篇
中国医学   4篇
肿瘤学   205篇
  2021年   34篇
  2020年   24篇
  2019年   26篇
  2018年   34篇
  2017年   40篇
  2016年   42篇
  2015年   49篇
  2014年   76篇
  2013年   114篇
  2012年   167篇
  2011年   168篇
  2010年   96篇
  2009年   80篇
  2008年   140篇
  2007年   134篇
  2006年   146篇
  2005年   151篇
  2004年   149篇
  2003年   151篇
  2002年   116篇
  2001年   155篇
  2000年   130篇
  1999年   134篇
  1998年   43篇
  1997年   47篇
  1996年   25篇
  1995年   23篇
  1994年   19篇
  1993年   18篇
  1992年   61篇
  1991年   48篇
  1990年   52篇
  1989年   58篇
  1988年   44篇
  1987年   42篇
  1986年   46篇
  1985年   40篇
  1984年   26篇
  1983年   21篇
  1982年   18篇
  1981年   17篇
  1979年   19篇
  1978年   21篇
  1977年   21篇
  1976年   32篇
  1975年   36篇
  1974年   29篇
  1973年   35篇
  1972年   18篇
  1971年   22篇
排序方式: 共有3422条查询结果,搜索用时 31 毫秒
61.

Objective

The objective of this study was to determine specific provider practices associated with high provider efficiency in community emergency departments (EDs).

Methods

A mixed‐methods study design was utilized to identify key behaviors associated with efficiency. Stage 1 was a convenience sample of 16 participants (ED medical directors, nurses, advanced practice providers, and physicians) identified provider efficiency behaviors during semistructured interviews. Ninety‐nine behaviors were identified and distilled by a group of three ED clinicians into 18 themes. Stage 2 was an observational study of 35 providers was performed in four (30,000‐ to 55,000‐visit) community EDs during two 4‐hour periods and recorded in minute‐by‐minute observation logs. In Stage 3, each behavior or practice from Stage 1 was assigned a score within each observation period. Behaviors were tested for association with provider efficiency (relative value units/hour) using linear univariate generalized estimating equations with an identity link, clustered on ED site.

Results

Five ED provider practices were found to be positively associated with efficiency: average patient load, using name of team member, conversations with health care team, visits to patient rooms, and running the board. Two behaviors, “inefficiency practices,” demonstrated significant negative correlations: non–work‐related tasks and documentation on patients no longer in the ED.

Conclusions

Average patient load, running the board, conversations with team member, and using names of team members are associated with enhanced provider productivity. Identification of behaviors associated with efficiency can be utilized by medical directors, clinicians, and trainees to improve personal efficiency or counsel team members.
  相似文献   
62.
Low- and middle-income countries account for the majority of hypertension disease burden. However, little is known about the distribution of this illness within subpopulations of these countries, particularly among those who live in urban informal settlements. A cross-sectional hypertension survey was conducted in 2003 among 5649 adult residents of a slum settlement in the city of Salvador, Brazil. Hypertension was defined as either an elevated arterial systolic (≥140 mmHg) or diastolic (≥90 mmHg) blood pressure. Sex-specific multivariable models of systolic blood pressure were constructed to identify factors associated with elevated blood pressure. The prevalence of hypertension in the population 18 years and older was 21 % (1162/5649). Men had 1.2 times the risk of hypertension compared with women (95 % confidence intervals (CI), 1.05, 1.36). Increasing age and lack of any schooling, particularly for women, were also significantly associated with elevated blood pressure (p < 0.05). There was also a direct association between men who were black and an elevated blood pressure. Among those who were hypertensive, 65.5 % were aware of their condition, and only 36.3 % of those aware were actively using anti-hypertensive medications. Men were less likely to be aware of their diagnosis or to use medications (p < 0.01 for both) than women. The prevalence of hypertension in this slum community was lower than reported frequencies in the non-slum population of Brazil and Salvador, yet both disease awareness and treatment frequency were low. Further research on hypertension and other chronic non-communicable diseases in slum populations is urgently needed to guide prevention and treatment efforts in this growing population.  相似文献   
63.
Mohr W 《Zeitschrift für Rheumatologie》2003,62(6):539-46; discussion 547
Inflammatory cartilage destruction in chronic arthritides is usually regarded as the process owing to chondrocytic chondrolysis or ingrowth of pannus tissue. Besides these two mechanisms a third one-cartilage degradation directly mediated by polymorphonuclear granulocytes (PMN's) of the synovial fluid-seems to be underestimated. There is growing evidence that PMN's are involved in several non-bacterial organ destructions (e.g., alcoholic hepatitis); thus, two case reports are presented demonstrating cartilage destruction by PMN's via the synovial fluid. It is shown by light and electron microscopy that in florid rheumatoid arthritis, PMN's from the inflamed synovial fluid can gain access to the cartilaginous surface. The adherence of PMN's to the superficial matrix, eventually mediated by immunocomplexes, may activate these cells with the subsequent secretion of destructive enzymes as well as reactive oxygen species. Cartilage degradation may be the consequence. From the morphological findings it is deduced that this mechanism may have important implications for inflammatory cartilage loss.  相似文献   
64.
Expression of viral or bacterial enzymes in tumor cells to convert nontoxic prodrugs into highly toxic metabolites is an attractive gene-therapeutic approach for the treatment of hepatocellular carcinoma (HCC). The Escherichia coli purine nucleoside phosphorylase (PNP) converts purine analogs into freely diffusible metabolites, which are highly toxic to dividing and nondividing cells. We investigated the antitumor effects of PNP in the human HCC cell lines, HepG2, Hep3B, and HuH-7, and performed a comparison with herpes simplex thymidine kinase (TK). The genes for PNP, TK, and enhanced green fluorescent protein (EGFP) were delivered to HCC cells by identical adenoviral vectors. Fludarabine and ganciclovir (GCV) served as prodrugs for PNP and TK, respectively. Expression of PNP highly sensitized HCC cells to fludarabine treatment. Fludarabine concentrations between 0.5 and 1 microg/mL killed 100% of the cells expressing PNP with no detectable toxicity in control cells expressing EGFP. Expression of PNP in as few as 10% of HCC cells induced efficient killing of most bystander cells. Expression of TK followed by GCV treatment produced a potent growth inhibition but failed to kill all TK-expressing HCC cells. More importantly, the TK system exhibited a lower degree of bystander effect. Adenoviral delivery of PNP followed by fludarabine administration prevented subcutaneous and intrahepatic tumor formation in nude mice and was also effective for the treatment of established tumors. These results demonstrate the potential of the PNP/fludarabine system for the treatment of HCC.  相似文献   
65.
BACKGROUND AND AIM OF THE STUDY: Intraoperative swabs of heart valves are obtained regularly from patients undergoing heart valve surgery for infective endocarditis (IE) in order to confirm the preoperative diagnosis and to adjust the antibiotic regimen. The study aim was to assess the diagnostic value of intraoperative swabs of heart valves in IE. METHODS: A total of 83 patients was referred for surgical treatment of active IE between October 1994 and May 1999. Preoperatively, microorganisms were isolated using a minimum of two positive blood cultures; results were compared with those obtained from intraoperative heart valve swab cultures. RESULTS: Preoperatively, 73 patients (88%) had a positive blood culture, and 10 (12%) had culture-negative endocarditis. The intraoperative swab confirmed the preoperative diagnosis in 31 cases (37%). Bacteria were isolated in three of the ten patients with preoperative culture-negative IE. Despite positive histopathological findings in seven patients, no microorganisms were cultured either pre- or intraoperatively. Among the remaining 42 patients (51%) with active IE, 25 valve cultures were sterile and 17 valve swabs were presumed to be contaminated. CONCLUSION: In patients with active IE in whom the causative agent could be isolated and identified before surgery, intraoperative valve swabs did not contribute further to patient management. In isolating contaminants, the risk of inappropriate modification of the antibiotic regimen is imminent. The diagnostic validity in culture-negative IE appears negligible.  相似文献   
66.
67.
Journal of Neurology - To evaluate the diagnostic accuracy and safety of extended stereotactic brain biopsy (ESBB) in a single center cohort with suspected primary angiitis of the central nervous...  相似文献   
68.
69.
70.
Objective To identify clinicopathologic factors associated with a reduced intercarotid distance (ICD) and subgroups at risk for internal carotid artery injury during transsphenoidal surgery. Design A retrospective case-control study. Setting This study was conducted at the McGill University Health Centre, a university-affiliated tertiary care center. Participants Patients with a sellar or parasellar tumor and nontumor controls were included in the study. Main Outcome Measures The smallest distance between the internal carotid arteries at the clival, cavernous, and paraclinoid segments on coronal magnetic resonance imaging was measured. Demographic profiles, cephalometric measurements, tumor dimensions, and sphenoid configuration were assessed as potential determinants of the ICD. Results A total of 212 cases and 34 controls were analyzed. Widening of the ICD at the three segments of the internal carotid arteries was found in patients with pituitary macroadenomas (p < 0.01). Patients with a growth hormone–secreting adenoma had a markedly reduced ICD at the clivus compared with controls (1.59 cm versus 1.77 cm; p = 0.02; 95% confidence interval [CI], 0.03–0.32). The paraclinoid ICD was reduced in patients with an anterior fossa meningioma (1.24 cm versus 1.33 cm; p = 0.04; 95% CI, 0.01–0.45). Conclusion Identifying clinicopathologic factors affecting the ICD can help surgeons recognize constraints to endoscopic access of the skull base and avoid inadvertent arterial injury.  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