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   1821篇
  免费   184篇
  国内免费   5篇
耳鼻咽喉   3篇
儿科学   42篇
妇产科学   30篇
基础医学   205篇
口腔科学   41篇
临床医学   153篇
内科学   387篇
皮肤病学   47篇
神经病学   81篇
特种医学   29篇
外科学   145篇
综合类   46篇
预防医学   156篇
眼科学   263篇
药学   148篇
中国医学   17篇
肿瘤学   217篇
  2023年   29篇
  2022年   32篇
  2021年   88篇
  2020年   56篇
  2019年   71篇
  2018年   83篇
  2017年   56篇
  2016年   66篇
  2015年   81篇
  2014年   99篇
  2013年   117篇
  2012年   148篇
  2011年   166篇
  2010年   70篇
  2009年   67篇
  2008年   119篇
  2007年   97篇
  2006年   89篇
  2005年   80篇
  2004年   62篇
  2003年   40篇
  2002年   50篇
  2001年   34篇
  2000年   26篇
  1999年   24篇
  1998年   14篇
  1997年   6篇
  1996年   10篇
  1995年   6篇
  1993年   7篇
  1992年   15篇
  1991年   9篇
  1990年   6篇
  1989年   4篇
  1988年   10篇
  1987年   7篇
  1986年   6篇
  1985年   4篇
  1984年   6篇
  1983年   5篇
  1982年   4篇
  1981年   3篇
  1979年   5篇
  1978年   3篇
  1977年   5篇
  1976年   2篇
  1975年   4篇
  1974年   2篇
  1973年   4篇
  1972年   4篇
排序方式: 共有2010条查询结果,搜索用时 15 毫秒
51.
Benign cardiac tumors are rare; they can present with nonspecific symptoms and represent a diagnostic challenge to the clinician. We describe an interesting case of a 26-year-old female who presented with a 6-month history of cough, breathlessness, palpitations, dizziness, and fever. Despite repeated clinical reviews in the community, diagnosis of cardiac tumor was not made until she developed decompensated cardiac failure with bilateral pleural effusions and pulmonary edema. Echocardiogram revealed an enormous left atrial mass that extended one-third into left ventricle during systole. The patient underwent successful surgical resection with histological confirmation of a benign atrial myxoma.  相似文献   
52.
Lymphoedema of the arm is a potentially serious consequence of any axillary procedure performed during the management of breast cancer. In an attempt to reduce its incidence and severity, patients are instructed to avoid venepunctures and blood pressure measurements on the treated arm. These precautions are not possible in some patients and attempts to adhere to them can cause discomfort, anxiety and stress for both patients and their health‐care workers. The strength with which these recommendations are made is in contrast to the level of evidence underpinning them. This paper reviews this evidence regarding the safety, or lack thereof, of blood pressure monitoring and intravenous puncture in women who have had axillary surgery. With this evidence generally being anecdotal in nature, there appears to be no rigorous evidence‐based support for the risk‐reduction behaviours of avoiding blood pressure monitoring and venepuncture in the affected arm in the prevention of lymphoedema after axillary procedure. A clinical trial was proposed to investigate whether such avoidance measures were valuable, but failed during its inception. There remains a need for research from prospective trials on this controversial topic to determine the most appropriate patient recommendations that should be provided after axillary procedure regarding the risks for development of lymphoedema.  相似文献   
53.
As a thermoelectric (TE) material suited to applications for recycling waste-heat into electricity through the Seebeck effect, poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonic acid) (PEDOT:PSS) is of great interest. Our research demonstrates a comprehensive study of different post-treatment methods with nitric acid (HNO3) to enhance the thermoelectric properties of PEDOT:PSS. The optimum conditions are obtained when PEDOT:PSS is treated with HNO3 for 10 min at room temperature followed by passing nitrogen gas (N2) with a pressure of 0.2 MPa. Upon this treatment, PEDOT:PSS changes from semiconductor-like behaviour to metal-like behaviour, with a simultaneous enhancement in the electrical conductivity and Seebeck coefficient at elevated temperature, resulting in an increase in the thermoelectric power factor from 0.0818 to 94.3 μW m−1 K−2 at 150 °C. The improvement in the TE properties is ascribed to the combined effects of phase segregation and conformational change of the PEDOT due to the weakened coulombic attraction between PEDOT and PSS chains by nitric acid as well as the pressure of the N2 gas as a mechanical means.

As a thermoelectric (TE) material suited to applications for recycling waste-heat into electricity through the Seebeck effect, poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonic acid) (PEDOT:PSS) is of great interest.  相似文献   
54.
55.
Purpose Tumor necrosis factor-α (TNF-α) is implicated in non-alcoholic steatohepatitis (NASH). Pentoxifylline inhibits TNF-α. We wanted to evaluate the efficacy of Pentoxifylline on NASH patients. Methods Patients with biopsy proven NASH and persistently elevated alanine aminotransferase (ALT) greater than 1.5 times the upper limit of normal were randomized to 3 months of treatment with a step 1 American Heart Association diet and daily exercise with Pentoxifylline or placebo. Liver function tests, serum lipids and TNF-α, Interleukin 6 (IL-6), and plasma hyaluronic acid were measured at baseline, at weeks 6 and 12. Categorical data were analyzed by Fisher’s exact test while independent sample t-test and Mann–Whitney test were used for continuous data. Results Eleven patients were randomized into the Pentoxifylline and nine to the placebo group. After 3 months of treatment body mass index (BMI), ALT and aspartate aminotransferase (AST) decreased significantly in both groups. There was no difference between the two groups in reduction of BMI (P = 0.897). There was significantly greater reduction in AST in the Pentoxifylline group (P = 0.038). There was a trend toward lower ALT level (P = 0.065) in the Pentoxifylline group. TNF-α and IL-6 decreased significantly in both groups after treatment, but there was no significant difference between the two groups. Conclusion Three months of Pentoxifylline treatment in combination with diet and exercise results in significantly greater reduction in AST levels in patients with NASH as compared with controls. This study was funded by the National Healthcare Group Small Innovative Grant NHG-grant number. RPR/04029. It received ethics approval by the National Healthcare Group Domain Specific Research Board D-registration number DSRB-D/04/083.  相似文献   
56.
The stability and tissue distribution of lipid vesicles modified at the surface by the incorporation of either a galactosyl ceramide (GalCer) or a galactosyl cholesterol (GalChol) glycoconjugate have been studied in mice by measuring the release of vesicle-entrapped 111In. Although the tissue distributions of both vesicle types were similar, the GalCer-containing vesicles were markedly less stable than those prepared with GalChol, whether administered orally or by intraperitoneal injection. Physical characterization of the vesicles in vitro suggests that the increased disruption rate for GalCer vesicles in vivo is related to structural instabilities induced by the cerebroside, which can then result in either an increased rate of vesicle uptake by tissues or a greater susceptibility to lysis. These studies demonstrate the importance of the nonpolar anchoring groups in determining the fate of surface-modified vesicles in vivo.  相似文献   
57.

Background

This study aimed to investigate the prevalence of pregnancy experience and its association with contraceptive knowledge among single adults in a low socio-economic suburban community in Kuala Lumpur, Malaysia.

Methods

A cross-sectional survey was conducted in 2012 among the Kerinchi suburban community. Of the total 3,716 individuals surveyed, young single adults between 18 and 35 years old were questioned with regard to their experience with unplanned pregnancy before marriage. Contraceptive knowledge was assessed by a series of questions on identification of method types and the affectivity of condoms for the prevention of sexually transmitted diseases.

Results

A total of 226 female and 257 male participants completed the survey. In total, eight female (3.5%) participants reported experience with an unplanned pregnancy before marriage, and five male (1.9 %) participants had the experience of impregnating their partners. The participants had a mean total score of 3.15 (SD = 1.55) for contraceptive knowledge out of a possible maximum score of five. Female participants who had experienced an unplanned pregnancy had a significantly lower contraceptive knowledge score (2.10 ± 1.48) than who had never experienced pregnancy (3.30 ± 1.35), p<0.05. Likewise, male participants who had experienced impregnating their partners had a significantly lower contraceptive knowledge score (1.60 ± 1.50) than those who did not have such experience (3.02 ± 1.59), p<0.05.

Conclusion

The results showed evidence of premarital unplanned pregnancy among this suburban community. The low level of contraceptive knowledge found in this study indicates the need for educational strategies designed to improve contraceptive knowledge.
  相似文献   
58.

Background

The breast cancer survival rate is the highest among all types of cancers, and survivors returning to work after completing treatment is extremely important in regards to economy and rehabilitation. The aim of this systematic review study is to identify the prevalence of breast cancer survivors who return to work (RTW) and the factors associated to RTW.

Methods

A computer based literature search was carried out. "PubMed, Cochrane Library, Embase, Web of Science, and Science Direct" databases were searched systematically. Our search strategy identified a total of 12,116 papers of which 26 studies met the inclusion criteria and quality assessment. These were original papers published between January 2003 and January 2013.

Results

The trends in RTW differ among countries for the breast cancer survivors. The time to RTW after successful cancer treatment also varies among the countries and by ethnicity. The prevalence of the RTW varies from 43% to 93% within one year of diagnosis. The prevalence of the RTW for the Netherland is the lowest in the world (43%). The United States survivors showed the highest RTW (93%) within 12 months of the diagnosis. Numerous barriers and facilitators were identified as factors that affect RTW. For instance, socio-demographic factors such as education and ethnicity; treatment oriented factors such as chemotherapy; work related factors such as heavy physical work; disease related factors such as poor health condition and fatigue; and psychological factors such as depression and emotional distress, act as barriers of RTW. In contrast, social, family, employer support, and financial independency emerge as key facilitators in enabling breast cancer survivors to return and continue work.

Conclusion

Minimising these identified barriers and strengthening these facilitators could further improve the work condition and increase the percentage of RTW among the breast cancer survivors.
  相似文献   
59.
60.
Early diagnosis and treatment yield optimal outcomes in rheumatoid arthritis (RA); thus, barriers to disease recognition must be identified and addressed. We determined the impact of sociodemographic factors, medical comorbidities, family history, and disease severity at onset on the time to diagnosis in early RA. The Canadian early ArThritis CoHort study data on 1,142 early RA patients were analyzed for predictors of time to diagnosis using regression analysis. Sociodemographic factors (age, sex, income strata, education, ethnicity), measures of disease activity (joint counts, DAS28 score, acute-phase reactants, patient global evaluation, function), family history, serology, chronic musculoskeletal and mental health conditions, and obesity at diagnosis were considered. In multivariate linear regression analysis, more swollen joints (β = ?0.047 per joint, 95 % CI ?0.085, ?0.010, p = 0.014), higher erythrocyte sedimentation rate (ESR) (β = ?0.012 per 1 mm/h, 95 % CI ?0.022, ?0.002, p = 0.0018), and worse patient global scores (β = ?0.082 per 1 unit on a visual analogue scale, 95 % CI ?0.158, ?0.006, p = 0.034) at baseline predicted a shorter time to diagnosis. Anti-cyclic citrullinated peptide (anti-CCP) antibody positivity (β = 0.688, 95 % CI 0.261, 1.115, p = 0.002) and low income (annual <$20,000 β = 1.185, 95 % CI 0.227, 2.143, p = 0.015; annual $20,000–50,000 β = 0.933, 95 % CI 0.069, 1.798, p = 0.034) increased time to diagnosis. In the logistic regression models, the odds of being diagnosed within 6 months of symptom onset were increased for each swollen joint present [odds ratio (OR) 1.04, 95 % CI 1.02–1.06 per joint], each 1 mm/h elevation in the ESR (OR 1.01, 95 % CI 1.00–1.02), and decreased for patients who were either rheumatoid factor or anti-CCP positive compared to both factors being negative (OR 0.68, 95 % CI 0.51–0.91). Higher disease activity results in a more rapid diagnosis for Canadian patients with early RA, but those with lower income have delays in diagnosis. Strategies to identify patients with a less severe disease presentation and in lower socioeconomic strata are needed to ensure equal opportunity for optimal management.  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