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   4478篇
  免费   317篇
  国内免费   12篇
耳鼻咽喉   42篇
儿科学   75篇
妇产科学   70篇
基础医学   765篇
口腔科学   52篇
临床医学   507篇
内科学   870篇
皮肤病学   37篇
神经病学   442篇
特种医学   228篇
外科学   690篇
综合类   14篇
一般理论   1篇
预防医学   397篇
眼科学   15篇
药学   376篇
肿瘤学   226篇
  2023年   21篇
  2022年   36篇
  2021年   101篇
  2020年   86篇
  2019年   108篇
  2018年   116篇
  2017年   94篇
  2016年   100篇
  2015年   109篇
  2014年   193篇
  2013年   263篇
  2012年   328篇
  2011年   365篇
  2010年   189篇
  2009年   187篇
  2008年   268篇
  2007年   298篇
  2006年   270篇
  2005年   257篇
  2004年   241篇
  2003年   190篇
  2002年   205篇
  2001年   66篇
  2000年   75篇
  1999年   80篇
  1998年   50篇
  1997年   45篇
  1996年   42篇
  1995年   44篇
  1994年   28篇
  1993年   25篇
  1992年   38篇
  1991年   45篇
  1990年   29篇
  1989年   33篇
  1988年   20篇
  1987年   15篇
  1986年   18篇
  1985年   16篇
  1984年   17篇
  1983年   14篇
  1982年   8篇
  1981年   6篇
  1980年   9篇
  1979年   7篇
  1978年   12篇
  1977年   4篇
  1972年   5篇
  1970年   4篇
  1967年   4篇
排序方式: 共有4807条查询结果,搜索用时 15 毫秒
91.
BACKGROUND: Brain natriuretic peptide (BNP) levels have been used to assess clinical status and predict prognosis of patients with chronic heart failure (CHF). However, BNP levels can only be measured in specialized laboratories which has hampered its use in daily clinical practice. We compared a new, rapid, BNP assay with a conventional BNP measurement and evaluated the applicability to current practice by comparing it with standard clinical parameters. METHODS: BNP levels were determined in 78 stable CHF patients and 20 controls. The severity of CHF was assessed by determination of New York Heart Association functional class (NYHA), left ventricular ejection fraction (LVEF) and peak oxygen consumption (peak VO(2)), and these parameters were compared to BNP levels. RESULTS: Overall, rapid BNP assessment was highly correlated with the conventional BNP assay (r=0.95, P<0.0001). In the higher ranges (>200 pmol/l), however, correlation was less accurate, and tended to overestimate. BNP levels also strongly correlated with both NYHA class, LVEF and peak VO(2) (all P<0.001). A cut-off value for BNP of 20 pmol/l yielded a sensitivity of 91% and a specificity of 92% to detect the presence of left ventricular systolic dysfunction. CONCLUSIONS: Rapid measurement of BNP levels is comparable to conventional BNP measurement and strongly correlated to clinical tests that are currently used to stratify CHF patients. Wider use of this method may yield a reduction of costly and time-consuming clinical tests and may reduce the medical burden of CHF.  相似文献   
92.

Purpose

The aim of the present study was to evaluate the efficacy of an oral formulation of Δ9-tetrahydrocannabinol (ECP002A) in patients with progressive multiple sclerosis (MS).

Methods

This accelerated proof-of-concept study consisted of 2 phases: a crossover challenge (dose-finding) phase and a 4-week, parallel, randomized, placebo-controlled treatment phase. Twenty-four patients with progressive MS and moderate spasticity were enrolled. During the treatment phase, biomarkers for efficacy and secondary pharmacodynamic effects were measured at baseline and after 2 and 4 weeks of treatment. Serum samples were collected to determine pharmacokinetic properties and perform population modeling. Safety and tolerability profiles were assessed based on adverse events and safety measurements.

Findings

Pain was significantly reduced when measured directly after administration of ECP002A in the clinic but not when measured in a daily diary. A similar pattern was observed in subjective muscle spasticity. Other clinical outcomes were not significantly different between active treatment and placebo. Cognitive testing indicated that there was no decline in cognition after 2 or 4 weeks of treatment attributable to ECP002A compared with placebo.ImplicationsThis study specifically underlines the added value of thorough investigation of pharmacokinetic and pharmacodynamic associations in the target population. Despite the complex interplay of psychoactive effects and analgesia, the current oral formulation of Δ9-tetrahydrocannabinol may play a role in the treatment of spasticity and pain associated with MS because it was well tolerated and had a stable pharmacokinetic profile.  相似文献   
93.
Objective: To examine patient safety culture in Dutch out-of-hours primary care using the safety attitudes questionnaire (SAQ) which includes five factors: teamwork climate, safety climate, job satisfaction, perceptions of management and communication openness.

Design: Cross-sectional observational study using an anonymous web-survey. Setting Sixteen out-of-hours general practitioner (GP) cooperatives and two call centers in the Netherlands. Subjects Primary healthcare providers in out-of-hours services. Main outcome measures Mean scores on patient safety culture factors; association between patient safety culture and profession, gender, age, and working experience.

Results: Overall response rate was 43%. A total of 784 respondents were included; mainly GPs (N?=?470) and triage nurses (N?=?189). The healthcare providers were most positive about teamwork climate and job satisfaction, and less about communication openness and safety climate. The largest variation between clinics was found on safety climate; the lowest on teamwork climate. Triage nurses scored significantly higher than GPs on each of the five patient safety factors. Older healthcare providers scored significantly higher than younger on safety climate and perceptions of management. More working experience was positively related to higher teamwork climate and communication openness. Gender was not associated with any of the patient safety factors.

Conclusions: Our study showed that healthcare providers perceive patient safety culture in Dutch GP cooperatives positively, but there are differences related to the respondents’ profession, age and working experience. Recommendations for future studies are to examine reasons for these differences, to examine the effects of interventions to improve safety culture and to make international comparisons of safety culture.
  • Key Points
  • Creating a positive patient safety culture is assumed to be a prerequisite for quality and safety. We found that:

  • ??healthcare providers in Dutch GP cooperatives perceive patient safety culture positively;

  • ??triage nurses scored higher than GPs, and older and more experienced healthcare professionals scored higher than younger and less experienced professionals – on several patient safety culture factors; and

  • ??within the GP cooperatives, safety climate and openness of communication had the largest potential for improvement.

  相似文献   
94.
West Nile virus (WNV) outbreaks in North America have been characterized by substantial die-offs of American crows (Corvus brachyrhynchos). In contrast, a low incidence of bird deaths has been observed during WNV epidemic activity in Europe. To examine the susceptibility of the western European counterpart of American crows, we inoculated carrion crows (Corvus corone) with WNV strains isolated in Greece (Gr-10), Italy (FIN and Ita09), and Hungary (578/10) and with the highly virulent North American genotype strain (NY99). We also inoculated American crows with a selection of these strains to examine the strains’ virulence in a highly susceptible bird species. Infection with all strains, except WNV FIN, resulted in high rates of death and high-level viremia in both bird species and virus dissemination to several organs. These results suggest that carrion crows are highly susceptible to WNV and may potentially be useful as part of dead bird surveillance for early warning of WNV activity in Europe.  相似文献   
95.
Integrating mental health care into residential homes for the elderly is a potentially effective model to address the complex care needs of older chronically mentally ill people. Because no research was available on the implementation of such integrated care in practice, six programs already operating in the Netherlands were analyzed. At the administrative level, three types of cooperative arrangements existed: a psychiatric hospital renting a unit in a residential home for the elderly, a psychiatric hospital stationing mental health professionals in a residential home on a permanent basis, and a residential home employing its own psychiatrically trained staff. At the operational level, contrasting views emerged on the relation-ship between physical and mental health care; these were delivered separately or in integrated form. In either case, the employees trained as elder care workers or as psychiatric nurses had difficulties understanding each other because they held different ideas about good-quality care. These care visions can be characterized as the care-giving approach (care workers) versus the problem-oriented and the rehabilitation approaches (nurses). At the housing level, two models existed: mentally ill patients having apartments in a separate unit (concentrated housing) or located throughout the facility (dispersed housing). The most promising model appears to be the one in which a psychiatric hospital assigns mental health professionals to work in a residential home, where they remain administratively and operationally distinct from the standard residential services. Whether or not the psychiatric residents should be housed in separate units could not be decided based on this study.  相似文献   
96.
Given the not infrequent need for intracardiac pacemaking during intensive cardiac care, a new type of cardiac pacemaker has been designed and tested [1]. With this pacemaker the heart can be stimulated through the fluid column of any conventional catheter, provided it is filled with a 0.9% NaCl solution. This fluid column pacemaker (FCP) is of the “constant current” type. The FCP was tested in 37 animals, in 30 patients in sinus rhythm, and also in two critical patients. In addition to the pacemaker circuit, a special connector was designed, enabling a fast, effective, and safe contact between patient and pacemaker. The FCP is considered to be ideally suited for use in emergency cardiac pacing in intensive care units and other areas where sudden bradycardias may occur and where intrathoracic catheters are inserted for a variety of reasons.  相似文献   
97.
PaO2, PaCO2 and pHa were measured via an extracorporeal loop in conscious snapping turtles (Chelydra serpentina) breathing air or hypoxic (10, 15% O2), hyperoxic (30% O2), or hypercapnic (2% CO2) gases. Turtles breathed into an inverted funnel ventilated with the test gas. Breathing was recorded with a differential pressure transducer. In all turtles, nonventilatory periods were interrupted by breathing episodes containing multiple breaths. In normoxia, PaO2 at the end of nonventilatory periods ranged from 22-128 mm Hg, although PaCO2 showed a less than 5 mm Hg variation about the mean. There was a positive correlation between PaCO2 at the end of the nonventilatory period and the number of breaths in the succeeding period of ventilation. PaCO2 at the end of nonventilatory periods did not change significantly in hyperoxia, although mean PaO2 was significantly increased. In hypoxia, on the other hand, mean PaO2 was significantly reduced and PaCO2 at the end of the nonventilatory period was slightly, but significantly lower. Nonventilatory periods were shorter when turtles breathed 15% O2 (9.3 +/- 1.2 min) or 10% O2 (5.5 +/- 0.3 min) than when they breathed air (17.6 +/- 3.4 min). The results indicate that, in undisturbed turtles, the most important stimulus triggering a breathing episode is the rise in PaCO2 to a critical value during the preceding nonventilatory period. An increase in hypoxic drive shortens the nonventilatory period. However, in normoxia, PaO2 at the end of many nonventilatory periods probably does not fall sufficiently to stimulate O2-sensitive chemoreceptors.  相似文献   
98.

Background  

Previous studies have indicated that a recently described anaerobic bacterium, Atopobium vaginae is associated with bacterial vaginosis (BV). Thus far the four isolates of this fastidious micro-organism were found to be highly resistant to metronidazole and susceptible for clindamycin, two antibiotics preferred for the treatment of BV.  相似文献   
99.
Conventional immunotherapy (IT) is effective in treating allergic rhinitis, allergic asthma, and chronic rhinosinusitis. Disadvantages include poor compliance, delayed efficacy, and patient frustration. Rush IT, or rapid desensitization, offers the advantages of rapid response, improved compliance, and cost-effectiveness. Although premedication with corticosteroids and antihistamines dramatically reduces systemic reactions, safety remains a primary concern. Two separate half-day schedules with minor differences were used to rapidly desensitize 893 patients (aged 1.5-77 years) in two typical outpatient settings equipped to treat anaphylaxis. All patients exhibited positive skin-prick tests to perennial and seasonal allergens. Diagnoses included allergic rhinitis (857/96%), allergic asthma (505/57%), and chronic rhinosinusitis (384/43%). Five hundred sixty-eight patients were premedicated with prednisone and HI-antihistamine for 3 days. Three hundred twenty-five patients were premedicated for 3 days with prednisone and H1- and H2-blockade. The protocol's final dose ranged from 0.1 to 0.5 mL of a 1:1000 dilution of extracts manufactured by ALK and Greer Laboratories. Patients continued on to higher doses by resuming a conventional schedule. Eighteen patients (2.0%) experienced a mild systemic reaction. All responded to subcutaneous epinephrine and/or nebulized albuterol and were sent home after observation. One patient (0.1%) experienced true anaphylaxis and received appropriate treatment and observation. Our experience with rush IT confirms that maintenance IT can be reached quickly and safely under careful supervision. Caution must be exercised when using this procedure because anaphylaxis does occur. Systemic reactions occur less frequently using a lower targeted final dose than previously described in the literature.  相似文献   
100.
Application of a dipstick assay for the detection of Salmonella typhi-specific IgM antibodies on samples collected from S. typhi or S. paratyphi culture-positive patients at the day of admission to the hospital revealed the presence of specific IgM antibodies in 43.5%, 92.9%, and 100% for samples collected 4-6 days, 6-9 days, and > 9 days after the onset of fever, respectively. The mean sensitivity for samples collected an average of 6.6 days after the onset of fever was 65.3%. Culture was positive in 65.9% of the cases with a final clinical diagnosis of typhoid fever. Testing of paired serum samples from culture negative patients with a final clinical diagnosis of typhoid fever resulted in staining of the dipstick in 4.3% of the samples collected at the day of admission to the hospital and in 76.6% of the samples collected one week later, thereby provided strong supporting evidence of typhoid fever by demonstrating seroconversion in a large proportion of the patients. The dipstick assay may thus also be useful for the serodiagnosis of culture-negative patients with clinical signs and symptoms consistent with typhoid fever. The advantages of the dipstick assay are that the result can be obtained on the same day allowing a prompt treatment, that only a small volume of serum is needed, and that no special laboratory equipment is needed to perform the assay. The stability of the reagents of the dipstick and the simplicity of the assay allows its use in places that lack laboratory facilities.  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