全文获取类型
收费全文 | 2077篇 |
免费 | 230篇 |
国内免费 | 7篇 |
专业分类
耳鼻咽喉 | 2篇 |
儿科学 | 98篇 |
妇产科学 | 16篇 |
基础医学 | 269篇 |
口腔科学 | 34篇 |
临床医学 | 222篇 |
内科学 | 507篇 |
皮肤病学 | 31篇 |
神经病学 | 148篇 |
特种医学 | 144篇 |
外科学 | 226篇 |
综合类 | 103篇 |
一般理论 | 1篇 |
预防医学 | 235篇 |
眼科学 | 12篇 |
药学 | 143篇 |
1篇 | |
中国医学 | 10篇 |
肿瘤学 | 112篇 |
出版年
2021年 | 21篇 |
2019年 | 22篇 |
2018年 | 35篇 |
2017年 | 20篇 |
2016年 | 25篇 |
2015年 | 45篇 |
2014年 | 33篇 |
2013年 | 60篇 |
2012年 | 78篇 |
2011年 | 77篇 |
2010年 | 49篇 |
2009年 | 62篇 |
2008年 | 70篇 |
2007年 | 73篇 |
2006年 | 101篇 |
2005年 | 70篇 |
2004年 | 78篇 |
2003年 | 64篇 |
2002年 | 57篇 |
2001年 | 57篇 |
2000年 | 58篇 |
1999年 | 65篇 |
1998年 | 44篇 |
1997年 | 66篇 |
1996年 | 60篇 |
1995年 | 51篇 |
1994年 | 51篇 |
1993年 | 45篇 |
1992年 | 58篇 |
1991年 | 48篇 |
1990年 | 47篇 |
1989年 | 44篇 |
1988年 | 51篇 |
1987年 | 39篇 |
1986年 | 30篇 |
1985年 | 33篇 |
1984年 | 24篇 |
1983年 | 40篇 |
1982年 | 35篇 |
1981年 | 26篇 |
1980年 | 21篇 |
1979年 | 22篇 |
1978年 | 14篇 |
1977年 | 16篇 |
1976年 | 28篇 |
1975年 | 24篇 |
1972年 | 14篇 |
1971年 | 17篇 |
1970年 | 21篇 |
1969年 | 13篇 |
排序方式: 共有2314条查询结果,搜索用时 15 毫秒
11.
Leukocyte-reduced transfusions in cardiac surgery results of an implementation trial 总被引:3,自引:0,他引:3
Blumberg N Heal JM Cowles JW Hicks GL Risher WH Samuel PK Kirkley SA 《American journal of clinical pathology》2002,118(3):376-381
An implementation trial of leukocyte-reduced transfusions in cardiac surgery (primary coronary artery bypass graft and valve replacement) was performed from July to December 1998; comparisons were made with data from the same period in 1997. Patients from both periods were similar in important preoperative and intraoperative variables (age, sex, weight, number of units of RBCs transfused, ejection fraction). The mean total number of complications was statistically significantly decreasedfrom 0.26 complications per patient in the non-leukocyte-reduced to 0.19 in the leukocyte-reduced recipients. Overall, the mean +/- ISD costs of care per patient decreasedfrom 1997 ($27,615 +/- $33,973) to 1998 ($27,038 +/- $24,107). Mean costs decreased $1,700 per patient for recipients of leukocyte-reduced blood in 1998 compared with recipients of non-leukocyte-reduced blood in 1997 Mean costs increased $4,000 per patient in patients who did not receive transfusions in 1998 compared with 1997. Hospitalization costs decreased when leukocyte-reduced transfusions were implemented for patients undergoing cardiac surgery in our institution. Implementation of leukocyte reduction may be cost neutral or cost saving in at least some settings. 相似文献
12.
Enhancement of resting activity in postganglionic vasoconstrictor neurones following short-lasting repetitive activation of preganglionic axons 总被引:1,自引:0,他引:1
Resting activity in postganglionic neurones supplying the cat hindlimb was enhanced after activation of preganglionic axons in the lumbar sympathetic trunk with short trains of stimuli (50 stimuli at 25 Hz). The characteristics of this enhancement were as follows: 1) It has values of 120 to 600% and lasts for 4 to more than 40 min. 2) It can be elicited heterosynaptically by repetitive stimulation of the peripheral end of a cut white ramus. 3) It is dependent on the activation of thin, probably unmyelinated, preganglionic axons. 4) It is probably produced by non-nicotinic (muscarinic and non-cholinergic) synaptic mechanisms in the sympathetic chain ganglia. 5) Vasoconstrictor neurones can be activated in this way, but not sudomotor neurones. The results argue that nicotinic transmission of activity from pre- to postganglionic vasoconstrictor neurones can be modulated heterosynaptically by slow non-nicotinic synaptic processes. 相似文献
13.
14.
Using the 1989 Medicare provider analysis and review (MEDPAR) file, we calculated a 30-day indirectly standardized mortality ratio (SMR) for all "fresh" acute myocardial infarction (AMI) Medicare aged cases (i.e., fresh AMI patients are those who had not reported an AMI in the prior 8 weeks) at 2,900 hospitals, as well as an indirectly standardized procedure ratio (SPR) of Swan-Ganz catheter (SGC) use for these AMI cases at each hospital. Cases at hospitals with higher SGC SPRs also had higher SMRs. This positive association persisted when hospitals were further stratified by their annual volume of fresh AMI cases. We believe that our use of cases as the unit of observation, stratified by the SGC SPR of their hospital, avoids some case selection bias in observational studies directly comparing risk-adjusted mortality of cases with and without SGC. 相似文献
15.
The purpose of this article is to introduce a new outcome-oriented, utilization-focused, and practical approach to program evaluation: Charting the Outcomes of Educational and Clinical Approaches (COECA) model. It provides a framework that encourages stakeholders to consider academic dissemination, product development, and implementation as three primary outcomes when evaluating educational and clinical approaches. The model then identifies measurements of the impact of each of these primary outcomes. Finally, it outlines three secondary outcomes that focus on education, clinical service, and administration. As an example, this article discusses the application of the model to an educational intervention in residency training. This intervention has been implemented at two sites. Secondary outcomes include increased competency of residents and a change in responsibilities among health care team members. The COECA model provides an easy-to-apply and efficient method for documenting actual progress and determining potential for further development. 相似文献
16.
Somnay-Wadgaonkar K Nusrat A Kim HS Canchis WP Balk SP Colgan SP Blumberg RS 《International immunology》1999,11(3):383-392
In order to better understand the role of intestinal CD1d, we sought to define the cellular localization and further characterize the biochemical structure of CD1d in human intestinal epithelial cells (IEC). Using a CD1d-specific rabbit anti-gst-CD1d antibody, immunoprecipitation of radiolabeled cell surface proteins detected a previously identified 37 kDa protein as well as a 48-50 kDa protein which were confirmed by Western blotting with a CD1d-specific mAb, D5. Immunoprecipitation of protein lysates with the CD1d-specific mAb, D5 and 51.1.3, and the beta2-microglobulin (beta2m)-specific mAb, BBM.1, followed by N-glycanase digestion and Western blotting with the D5 mAb showed that the 48-50 kDa protein was a beta2m-associated, CD1d glycoprotein. CD1d was immunolocalized to the apical and lateral regions of native small and large intestinal IEC as defined by confocal laser microscopy using the D5 mAb and the rabbit anti-gst-CD1d antibody. In addition, a large apical intracellular pool of CD1d was identified. Identical observations were made with polarized T84 cells. Selective biotin labeling of apical and basolateral cell surfaces followed by immunoprecipitation with the D5 mAb, N-glycanase digestion and avidin blotting confirmed the presence of glycosylated CD1d on both cell surfaces and immunolocalization of the 37 kDa non-glycosylated form of CD1d to the apical cell surface. These studies show that CD1d is located in an ideal position for luminal antigen sampling and presentation to subjacent intraepithelial lymphocytes. 相似文献
17.
M J Sotir C Lewis E W Bisher S M Ray J M Soucie H M Blumberg 《Infection control and hospital epidemiology》1999,20(3):187-191
OBJECTIVE: To examine risk factors for, and determine the incidence of, device-associated infections among patients with an implantable vascular access device. SETTING: Grady Health System, including a 1,000-bed, inner-city, public, teaching hospital and human immunodeficiency virus (HIV), oncology, and sickle cell clinics in Atlanta, Georgia. PATIENTS: 123 consecutive patients who received a PAS-Port implantable venous access device between January 1 and June 30, 1995. DESIGN: Retrospective cohort study with follow-up > or = 1 year following device implantation. RESULTS: Underlying illnesses included HIV infection in 66 patients (median CD4 count, 24.4 cells/mm3), malignancy in 51, and sickle cell disease in 6. Mean age of patients was 43.7 years, 50% were male, and 74% were black. Thirty-one (25%) of 123 patients developed a primary or device-associated bloodstream infection (BSI), and 3 of the 31 patients experienced two separate episodes of infection. The overall rate of infection was 1.23 primary BSIs per 1,000 device days. Patients with cancer had a lower rate of infection than those with HIV infection, but the difference was not statistically significant (0.96 vs 1.50 BSIs/1,000 device days; relative risk, 0.58; 95% confidence interval, 0.27-1.26). Subgroup analysis of patients with different malignancies indicated that infection rates differed according to type of cancer, and there was a trend for heterogeneity across the different cancer strata (P=.06). Gram-positive pathogens accounted for 60% of the pathogens recovered. Six (19%) of 31 patients who developed an infection did so within the first 14 days after implantation. In 11 (32%) of the 34 BSIs, the port required removal; two patient deaths were attributed to device-associated bacteremias (0.072 deaths/1,000 device days). CONCLUSIONS: Approximately one fourth of patients who had a vascular access device implanted developed a primary BSI, but the overall infection rate (per 1,000 device days) was relatively low, even among those with HIV infection. Primary BSI rates in patients with vascular access devices appeared to differ according to the specific underlying illness. 相似文献
18.
Introduction
The reflex sympathetic dystrophy (RSD) syndrome usually shows a distally generalized distribution pattern of symptoms. Here we report a case with a distally localized form of RSD.Patient and methods
In a 53-year-old woman, following a local lesion in the nail bed of the left thumb, a neuroma developed at the side of the lesion during the next half year. She was finally operated upon. Following that intervention, a complex and painful clinical syndrome occurred that for the most part affected only the thumb. A clinical neurological examination was carried out, including distal suprasystolic compression of the affected extremity after bandaging it (the so-called ischemia test). For diagnostic and therapeutic reasons, afterwards a conventional blockade of the ipsilateral stellate ganglion was applied.Results
The clinical investigation showed a triad of autonomic (swelling, side difference of skin temperature, hyperhydrosis), motor (reduced movement ability, tremor) and sensory disturbances (spontaneous pain, allodynia), which nearly exclusively affected the entire left thumb. The spontaneous pain showed an orthostatic component (the pain being diminished or exaggerated when the extremity was elevated or lowered, respectively) and was suppressed by the ischemia test. Following the sympathetic block, all symptoms disappeared within one day (follow-up period: 5 months).Conclusion
In contrast to the common clinical picture of RSD, with a distally generalized distribution of symptoms, the present case showed a so-called localized form of RSD, its triad affecting only the thumb with the lesion. Typically, the pain showed an orthostatic component and was suppressed by the ischemia test. The sympathetic block was immediately successful, proving the occurrence of this form of RSD for the first time. In similar clinical cases, this form of RSD should be considered as a differential diagnosis. 相似文献19.
Health status of cable splicers with low-level exposure to lead: results of a clinical survey 总被引:1,自引:1,他引:0 下载免费PDF全文
A Fischbein J Thornton W E Blumberg J Bernstein J A Valciukas M Moses B Davidow B Kaul M Sirota I J Selikoff 《American journal of public health》1980,70(7):697-700
The results of a cross-sectional clinical field survey of 90 telephone cable splicers are presented. Despite the rare occurrence of clinically overt lead poisoning among cable splicers, the observed prevalence of symptoms was 29% for lead-associated central nervous system symptoms and 21% for gastrointestinal symptoms. These two groups of symptoms were directly related to zinc protoporphyrin (ZPP) levels but no relationship was found between them and blood lead concentrations. Only 5% of the workers had significantly elevated blood lead levels (greater than 40 microgram/100ml). Because of the intermittent lead exposure encountered in this trade, individuals were identified with "normal" blood lead levels associated with "elevated" zinc protoporphyrin concentrations, indicating the difference in biological significance between exposure-(blood lead) and biological-response tests (ZPP). Suggestion is made that both types of diagnostic tests be utilized in the medical surveillance of lead-exposured workers. 相似文献
20.
Non-invasive detection of fecal protein kinase C betaII and zeta messenger RNA: putative biomarkers for colon cancer 总被引:2,自引:0,他引:2
Davidson LA; Aymond CM; Jiang YH; Turner ND; Lupton JR; Chapkin RS 《Carcinogenesis》1998,19(2):253-257
We have developed a non-invasive method utilizing feces, containing
sloughed colonocytes, as a sensitive technique for detecting diagnostic
colonic biomarkers. In this study, we used the rat colon carcinogenesis
model to determine if changes in fecal protein kinase C (PKC) expression
have predictive value in monitoring the neoplastic process. Weanling rats
were injected with saline or azoxymethane (AOM) and 36 weeks later fecal
samples and mucosa were collected, poly A+ RNA isolated, and quantitative
RT-PCR performed using primers to PKC betaII and zeta. Fecal PKC betaII and
zeta mRNA levels were altered by the presence of a tumor, with
tumor-bearing animals having a 3-fold higher (P < 0.05) PKC betaII
expression as compared with animals without tumors. In addition,
AOM-injection increased mucosal PKC betaII mRNA expression compared with
saline controls. No effect of tumor incidence on mucosal PKC betaII
expression was observed. In contrast, fecal PKC zeta expression was
2.5-fold lower (P < 0.05) in animals injected with azoxymethane versus
saline. Since tumor incidence exerts a reciprocal effect on fecal PKC
betaII and zeta mRNA expression, data were also expressed as the ratio
between PKC betaII and zeta. The isozyme ratio was strongly related to
tumor incidence, i.e. ratio for animals with tumors was 2.18 +/- 1.25,
animals without tumors was 0.50 +/- 0.16, P = 0.025. We demonstrate that
the expression of fecal PKC betaII and zeta may serve as a noninvasive
marker for development of colon tumors. A sensitive technique for the
detection of colon cancer is of importance since early diagnosis can
substantially reduce mortality.
相似文献