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   1227篇
  免费   69篇
  国内免费   44篇
耳鼻咽喉   6篇
儿科学   58篇
妇产科学   21篇
基础医学   184篇
口腔科学   66篇
临床医学   103篇
内科学   270篇
皮肤病学   11篇
神经病学   97篇
特种医学   209篇
外国民族医学   1篇
外科学   55篇
综合类   19篇
预防医学   86篇
眼科学   14篇
药学   50篇
中国医学   1篇
肿瘤学   89篇
  2020年   6篇
  2019年   14篇
  2018年   9篇
  2017年   6篇
  2016年   5篇
  2015年   21篇
  2014年   26篇
  2013年   25篇
  2012年   17篇
  2011年   30篇
  2010年   25篇
  2009年   26篇
  2008年   39篇
  2007年   46篇
  2006年   34篇
  2005年   30篇
  2004年   25篇
  2003年   30篇
  2002年   36篇
  2001年   30篇
  2000年   25篇
  1999年   36篇
  1998年   39篇
  1997年   39篇
  1996年   41篇
  1995年   33篇
  1994年   50篇
  1993年   28篇
  1992年   22篇
  1991年   33篇
  1990年   29篇
  1989年   57篇
  1988年   47篇
  1987年   50篇
  1986年   59篇
  1985年   32篇
  1984年   34篇
  1983年   22篇
  1982年   15篇
  1981年   15篇
  1980年   12篇
  1979年   17篇
  1978年   8篇
  1977年   8篇
  1976年   10篇
  1975年   10篇
  1974年   6篇
  1973年   8篇
  1971年   7篇
  1970年   5篇
排序方式: 共有1340条查询结果,搜索用时 15 毫秒
71.
Providing safe, error-free care is the number-one priority of all health care professionals. Excellent outcomes have been associated with procedural efficiency, the implementation of evidence-based standards, and the use of tools designed to reduce the likelihood of medical error (such as computerized medication orders and bar-coded patient identification). But the impact of work relationships on clinical outcomes isn't as well documented.The current survey was designed as a follow-up to a previous VHA West Coast survey that examined the prevalence and impact of physicians' disruptive behavior on the job satisfaction and retention of nurses (see "Nurse-Physician Relationships: Impact on Nurse Satisfaction and Retention," June 2002). Based on the findings of that survey and subsequent comments on it, the follow-up survey examined the disruptive behavior of both physicians and nurses, as well as both groups' and administrators' perceptions of its effects on providers and its impact on clinical outcomes.Surveys were distributed to 50 VHA hospitals across the country, and results from more than 1,500 survey participants were evaluated. Nurses were reported to have behaved disruptively almost as frequently as physicians. Most respondents perceived disruptive behavior as having negative or worsening effects, in both nurses and physicians, on stress, frustration, concentration, communication, collaboration, information transfer, and workplace relationships. Even more disturbing was the respondents' perceptions of negative or worsening effects of disruptive behavior on adverse events, medical errors, patient safety, patient mortality, the quality of care, and patient satisfaction. These findings suggest that the consequences of disruptive behavior go far beyond nurses' job satisfaction and morale, affecting communication and collaboration among clinicians, which may well, in turn, have a negative impact on clinical outcomes. Strategies aimed at reducing the incidence and impact of disruptive behavior are recommended.  相似文献   
72.
Differential CT diagnosis of extruded nucleus pulposus   总被引:1,自引:0,他引:1  
  相似文献   
73.
There is a growing body of evidence on the role of nitric oxide (NO) in human platelet physiology regulation. Recently, interest has developed in the functional role of an alternative redox form of NO, namely nitroxyl (HNO/NO-), because it is formed by a number of diverse biochemical reactions. The aim of the present study was to comparatively analyze the effect of HNO and NO on several functional parameters of human platelets. For this purpose, sodium trioxodinitrate (Angeli's salt,AS) and sodium nitroprusside (SNP) were used as HNO and NO releasers, respectively. BothAS and SNP significantly inhibited platelet aggregation and ATP release induced by different agonists and adrenaline. AS or SNP did not modify the expression of platelet glycoproteins (Ib, IIb-IIIa, la-IIa, IV), whereas they substantially decreased the levels of CD62P, CD63 and of PAC-1 (a platelet activated glycoprotein IIb/IIIa epitope) after the stimulation with ADP. AS and SNP significantly increased cGMP accumulation in a 1H-[1,2,4]oxadiazolo [4,3-a] quinoxalin-1-one (ODQ)-sensitive manner. However, while L-cysteine reduced the effect of AS, it increased the effect of SNP on this parameter. Accordingly, a differential effect of L-cysteine was observed on the antiaggregatory effect of both compounds. In summary, these results indicate that HNO is an effective inhibitor of human platelet aggregation.  相似文献   
74.
Decision-Making Capacity and Disaster Research   总被引:3,自引:0,他引:3  
The extent to which victims of a disaster are able to make capacitated and voluntary decisions to enroll in research is an important and virtually unexplored question. Although there are no compelling data to suggest that experiencing a severe trauma, in and of itself, renders all or even most individuals incapable of making autonomous decisions, the assessment of decision-making capacity (DMC) for research participation warrants serious consideration. This paper provides a framework for and procedural approach to the assessment of DMC in research with individuals exposed to disaster. Particular attention is paid to the implementation of additional safeguards to protect subjects who are vulnerable by virtue of impaired DMC. Recommendations are offered to clinical investigators, ethical review boards, and policymakers with regard to the design, review, and conduct of research in the aftermath of disaster.  相似文献   
75.
PURPOSE: To analyze the dose/fractionation schedules currently used in ongoing clinical trials of partial breast irradiation (PBI) by comparing their biologically effective dose (BED) values to those of three standard whole breast protocols commonly used after segmental mastectomy in the treatment of breast cancer. METHODS AND MATERIALS: The BED equation derived from the linear-quadratic model for radiation-induced cell killing was used to calculate the BEDs for three commonly used whole breast radiotherapy regimens, in addition to a variety of external beam radiotherapy, as well as high-dose-rate and low-dose-rate brachytherapy, PBI protocols. RESULTS: The BED values of most PBI protocols resulted in tumor control BEDs roughly equivalent to a 50-Gy standard treatment, but consistently lower than the BEDs for regimens in which the tumor bed receives a total dose of either 60 Gy or 66 Gy. The BED values calculated for the acute radiation responses of erythema and desquamation were nearly all lower for the PBI schedules, and the late-response BEDs for most PBI regimens were in a similar range to the BEDs for the standard treatments. CONCLUSION: Biologically effective dose modeling raises the concern that inadequate doses might be delivered by PBI to ensure optimal in-field tumor control.  相似文献   
76.
The aim of this study was to analyse how the results of Gram-staining vaginal smears correlated with the clinical criteria for determining the existence of bacterial vaginosis (BV) and, in particular, how the category defined as 'intermediate' or Gram grade II did so and its significance. Women attending an antenatal clinic with an abnormal vaginal flora, that is those who had Gram-stains of grades II or III, the latter considered to equate with BV, were given clindamycin or a placebo intravaginally and examined again on up to three occasions. Gram-stain readings of grade III correlated with the clinical criteria for BV on 356 (91.7%) of 388 occasions. Grade II readings covered the spectrum of clinical criteria and correlated with those for BV on 35 (37.2%) of 94 occasions. Grade I, recorded 231 times and seen usually after clindamycin treatment, was associated with BV only once. The sensitivity, specificity, positive predictive value and negative predictive value of the Gram stain for the diagnosis of BV, based on a combination of grades II and III, were 99.7%, 71.6%, 81% and 99.6%, respectively; based on grade III only, the values were 99.7%, 87.7%, 91.6% and 99.6%, respectively. Women reported a malodorous vaginal discharge on 49.2% of the occasions a grade III flora was seen and 13.3% of the times grade II was recorded. It was not associated with grade I and would seem a useful adjunct to the accepted clinical criteria for diagnosing BV. Each of the clinical criteria was found in about equal proportions (87%-91%) for women whose Gram grade was III. For grade II, an increased discharge was noted most often (76.5%) and 'clue' cells least often (24.5%). A positive amine test was the most specific, being associated with <1% of grade I smears. Of women with grade III status, 91% reverted to grade I after treatment with clindamycin for three days. In contrast, of women with grade II status, 53% reverted to grade I, as did 47% of those who were given a placebo. The 'intermediate' (grade II) category is a Gram-stain diagnosis and not one that can be made clinically. It is important to recognize as a distinct entity not only because amalgamation with grade III diminishes the specificity and positive predictive value of the Gram-stain for diagnosing BV, but also because women of grade II status usually fail to respond to clindamycin treatment, whereas those of grade III do not.  相似文献   
77.
Haemophilus influenzae type b (Hib) invasive disease and oropharyngeal carriage continue in rural Alaska despite widespread vaccination. This study investigated whether invasive-disease reemergence during 1996-1997 could be attributed to strains distinguishable from strains carried by vaccinated children. Twenty-four invasive and 42 carriage Hib isolates, collected during 1992-1997, were characterized by pulsed-field gel electrophoresis (PFGE), multilocus enzyme electrophoresis, and biotyping. This Hib population was highly clonal, since only 2 strains, electrophoretic type (ET) 55/PFGE 1 and ET 56/PFGE 3, accounted for 62% of all isolates. The ET 55/PFGE 1 and ET 56/PFGE 3 strains were found in 74% of the carriers and caused 80% of the invasive Hib disease that occurred during April 1996-March 1997. Strains causing invasive disease could not be distinguished from strains carried by vaccinated children. Continued monitoring of Hib carriage may provide insights into the epidemiology of continued transmission in an era of widespread vaccination.  相似文献   
78.
Adventure travel is becoming more popular, increasing the likelihood of contact with unusual pathogens. We investigated an outbreak of leptospirosis in "Eco-Challenge" multisport race athletes to determine illness etiology and implement public health measures. Of 304 athletes, we contacted 189 (62%) from the United States and 26 other countries. Eighty (42%) athletes met our case definition. Twenty-nine (36%) case-patients were hospitalized; none died. Logistic regression showed swimming in the Segama River (relative risk [RR]=2.0; 95% confidence interval [CI]=1.3 to 3.1) to be an independent risk factor. Twenty-six (68%) of 38 case-patients tested positive for leptospiral antibodies. Taking doxycycline before or during the race was protective (RR=0.4, 95% CI=0.2 to 1.2) for the 20 athletes who reported using it. Increased adventure travel may lead to more frequent exposure to leptospires, and preexposure chemoprophylaxis for leptospirosis (200 mg oral doxycycline/week) may decrease illness risk. Efforts are needed to inform adventure travel participants of unique infections such as leptospirosis.  相似文献   
79.
Context  Elevated rates of meningococcal disease were noted among 18- to 22-year-olds in the mid-1990s. However, national data on rates of meningococcal disease in US college students were not collected until 1998. Objectives  To determine rates of meningococcal disease in US college students and to identify risk factors for meningococcal disease in this population. Design, Setting, and Patients  Prospective surveillance study with nested case-control study of US college students with meningococcal infection from September 1, 1998, to August 31, 1999. Fifty state health departments and 231 college health centers participated. Main Outcome Measures  Incidence of and risk factors for meningococcal disease in US college students. Results  Ninety-six cases of meningococcal disease were identified. The incidence rate for undergraduates was 0.7 per 100 000 persons vs 1.4 per 100 000 for the general population of 18- to 23-year-old nonstudents (P<.001). Freshmen living in dormitories had the highest incidence rate at 5.1 per 100 000. Of the 79 case-patients for whom information was available, 54 (68%) had illness due to vaccine-preventable meningococcal serogroups. On multivariable analysis of case-control study data, freshmen who lived in dormitories had an elevated risk of meningococcal disease (matched odds ratio, 3.6; 95% confidence interval, 1.6-8.5; P = .003) compared with other college students. Conclusions  Freshmen who live in dormitories have an independent, elevated risk of meningococcal disease compared with other college students. Use of the currently available quadrivalent polysaccharide vaccine among college students could substantially decrease their risk of meningococcal disease.   相似文献   
80.
1. The subcellular mechanisms regulating stimulus-contraction coupling in detrusor remain to be determined. We used Ca(2+)-free solutions, Ca(2+) channel blockers, cyclopiazonic acid (CPA), and RhoA kinase (ROK) inhibitors to test the hypothesis that Ca(2+) influx and Ca(2+) sensitization play primary roles. 2. In rabbit detrusor, peak bethanechol (BE)-induced force was inhibited 90% by incubation for 3 min in a Ca(2+)-free solution. By comparison, a 20 min incubation of rabbit femoral artery in a Ca(2+)-free solution reduced receptor-induced force by only 5%. 3. In detrusor, inhibition of sarcoplasmic reticular (SR) Ca(2+) release by 2APB, or depletion of SR Ca(2+) by CPA, inhibited BE-induced force by only 27%. The CPA-insensitive force was abolished by LaCl3. By comparison, 2APB inhibited receptor-induced force in rabbit femoral artery by 71%. 4. In the presence of the non-selective cation channel (NSCC) inhibitor, LOE-908, BE did not produce an increase in [Ca(2+)]i but did produce weak increases in myosin phosphorylation and force. 5. Inhibitors of ROK-induced Ca(2+) sensitization, HA-1077 and Y-27632, inhibited BE-induced force by approximately 50%, and in combination with LOE-908, nearly abolished force. 6. These data suggest that two principal muscarinic receptor-stimulated detrusor contractile mechanisms include NSCC activation, that elevates [Ca(2+)]i and ROK activation, that sensitizes cross bridges to Ca(2+).  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