全文获取类型
收费全文 | 51883篇 |
免费 | 4970篇 |
国内免费 | 675篇 |
专业分类
耳鼻咽喉 | 612篇 |
儿科学 | 1109篇 |
妇产科学 | 843篇 |
基础医学 | 2376篇 |
口腔科学 | 1033篇 |
临床医学 | 9669篇 |
内科学 | 5567篇 |
皮肤病学 | 620篇 |
神经病学 | 3300篇 |
特种医学 | 1105篇 |
外科学 | 4818篇 |
综合类 | 5782篇 |
一般理论 | 6篇 |
预防医学 | 10148篇 |
眼科学 | 292篇 |
药学 | 5984篇 |
83篇 | |
中国医学 | 1783篇 |
肿瘤学 | 2398篇 |
出版年
2024年 | 99篇 |
2023年 | 1171篇 |
2022年 | 1975篇 |
2021年 | 2787篇 |
2020年 | 2849篇 |
2019年 | 2713篇 |
2018年 | 2544篇 |
2017年 | 2355篇 |
2016年 | 2247篇 |
2015年 | 2009篇 |
2014年 | 4487篇 |
2013年 | 4676篇 |
2012年 | 3321篇 |
2011年 | 3528篇 |
2010年 | 2564篇 |
2009年 | 2561篇 |
2008年 | 2483篇 |
2007年 | 2376篇 |
2006年 | 1867篇 |
2005年 | 1598篇 |
2004年 | 1245篇 |
2003年 | 989篇 |
2002年 | 771篇 |
2001年 | 698篇 |
2000年 | 595篇 |
1999年 | 494篇 |
1998年 | 374篇 |
1997年 | 347篇 |
1996年 | 315篇 |
1995年 | 262篇 |
1994年 | 235篇 |
1993年 | 178篇 |
1992年 | 155篇 |
1991年 | 123篇 |
1990年 | 90篇 |
1989年 | 68篇 |
1988年 | 58篇 |
1987年 | 55篇 |
1986年 | 42篇 |
1985年 | 56篇 |
1984年 | 43篇 |
1983年 | 22篇 |
1982年 | 26篇 |
1981年 | 24篇 |
1980年 | 14篇 |
1979年 | 12篇 |
1978年 | 4篇 |
1976年 | 3篇 |
1975年 | 8篇 |
1974年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 327 毫秒
62.
《Value in health》2022,25(12):1958-1966
ObjectivesNational health technology assessments (HTAs) across Europe show differences in evidentiary requirements from assessments by the European Medicines Agency (EMA), affecting time to patient access for drugs after marketing authorization. This article analyzes the differences between EMA and HTA bodies’ evidentiary requirements for oncology drugs and provides recommendations on potential further alignment to minimize and optimally manage the remaining differences.MethodsInterviews were performed with representatives and drug assessment experts from EMA and HTA bodies to identify evidentiary requirements for several subdomains and collect recommendations for potentially more efficiently addressing differences. A comparative analysis of acceptability of the evidence by EMA and the HTA bodies and for potential further alignment between both authorities was conducted.ResultsAcceptability of available evidence was higher for EMA than HTA bodies. HTA bodies and EMA were aligned on evidentiary requirements in most cases. The subdomains showing notable differences concerned the acceptance of limitation of the target population and extrapolation of target populations, progression-free survival and (other) surrogate endpoints as outcomes, cross-over designs, short trial duration, and clinical relevance of the effect size. Recommendations for reducing or optimally managing differences included joint early dialogues, joint relative effectiveness assessments, and the use of managed entry agreements.ConclusionsDifferences between assessments of EMA and HTA bodies were identified in important areas of evidentiary requirements. Increased alignment between EMA and HTA bodies is suggested and recommendations for realization are discussed. 相似文献
63.
Sandrine F. Chebekoue 《Journal of occupational and environmental hygiene》2019,16(4):308-319
This study aimed at deriving occupational thresholds of toxicological concern for inhalation exposure to systemically-acting organic chemicals using predicted internal doses. The latter were also used to evaluate the quantitative relationship between occupational exposure limit and internal dose. Three internal dose measures were identified for investigation: (i) the daily area under the venous blood concentration vs. time curve, (ii) the daily rate of the amount of parent chemical metabolized, and (iii) the maximum venous blood concentration at the end of an 8-hr work shift. A dataset of 276 organic chemicals with 8-hr threshold limit values-time-weighted average was compiled along with their molecular structure and Cramer classes (Class I: low toxicity, Class II: intermediate toxicity, Class III: suggestive of significant toxicity). Using a human physiologically-based pharmacokinetic model, the three identified dose metrics were predicted for an 8-hr occupational inhalation exposure to the threshold limit value for each chemical. Distributional analyses of the predicted dose metrics were performed to identify the percentile values corresponding to the occupational thresholds of toxicological concern. Also, simple linear regression analyses were performed to evaluate the relationship between the 8-hr threshold limit value and each of the predicted dose metrics, respectively. No threshold of toxicological concern could be derived for class II due to few chemicals. Based on the daily rate of the amount of parent chemical metabolized, the proposed internal dose-based occupational thresholds of toxicological concern were 5.61?×?10?2 and 9?×?10?4 mmol/d at the 10th percentile level for classes I and III, respectively, while they were 4.55?×?10?1 and 8.5?×?10?3 mmol/d at the 25th percentile level. Even though high and significant correlations were observed between the 8-hr threshold limit values and the predicted dose metrics, the one with the rate of the amount of chemical metabolized was remarkable regardless of the Cramer class (r2 = 0.81; n = 276). The proposed internal dose-based occupational thresholds of toxicological concern are potentially useful for screening-level assessments as well as prioritization within an integrated occupational risk assessment framework. 相似文献
64.
65.
《Biomedical and environmental sciences : BES》2022,35(9):773-781
ObjectiveImprovement in the quality of life is reflected in the narrowing of the gap between health-adjusted life expectancy (HALE) and life expectancy (LE). The effect of megacity expansion on narrowing the gap is rarely reported. This study aimed to disclose this potential relationship.MethodsAnnual life tables were constructed from identified death records and population counts from multiple administrative sources in Guangzhou, China, from 2010 to 2020. Joinpoint regression was used to evaluate the temporal trend. Generalized principal component analysis and multilevel models were applied to examine the county-level association between the gap and social determinants.ResultsAlthough LE and HALE in megacities are increasing steadily, their gap is widening. Socio-economic and health services are guaranteed to narrow this gap. Increasing personal wealth, a growing number of newborns and healthy immigrants, high urbanization, and healthy aging have helped in narrowing this gap.ConclusionIn megacities, parallel LE and HALE growth should be highly considered to narrow their gap. Multiple social determinants need to be integrated as a whole to formulate public health plans. 相似文献
66.
67.
《Arab Journal Of Gastroenterology》2021,22(3):229-235
Background and Study AimsIn developing countries, endemic indications, blood shortages, and the scarcity of liver surgeons and intensive care providers can affect liver resection (LR) outcomes, but these have been rarely addressed in the literature. Therefore, in this study we determined risk factors for major complications after LR in a North African general surgery and teaching department.Patients and MethodsFrom January 2010 to December 2015, 213 consecutive LRs were performed on 203 patients. All patients underwent a postoperative follow-up of >90 days. Postoperative complications were assessed according to the Clavien–Dindo (CD) classification of surgical complications. A score of CD ≥III is considered as major postoperative complications. In this study, we analyzed the variables assumed to affect these complications.ResultsThe overall 90-day complication rate was 35.7% (n = 76), including a CD ≥III of 14% (n = 30) and a mortality rate of 6.1% (n = 14). According to the multivariate analysis, a preoperative performance status (PS) of ≥2 (P = 0.011; odds ratios [OR], 6.8; 95% confidence intervals [CI], 1.55–29.8), an estimated intraoperative blood loss of >500 ml (P = 0.002; OR, 3.71; 95% CI, 1.23–11.20), and bilioenteric anastomosis (P < 0.004; OR, 7.76; 95% CI, 1.5–3.89) were independent risk factors for major complications after LR.ConclusionWe recommend that, in the setting of a non-Eastern/non-Western general surgery and teaching department, patients with a PS of ≥2 should undergo a specific selection and preoperative optimization protocol; intermittent clamping indications should be extended; and special attention should paid to patients undergoing LR associated with biliary reconstruction, such as for perihilar cholangiocarcinoma. 相似文献
68.
《Burns : journal of the International Society for Burn Injuries》2022,48(1):201-214
BackgroundThere is an urgent need to empower practitioners to undertake quality improvement (QI) projects in burn services in low-middle income countries (LMICs). We piloted a course aimed to equip nurses working in these environments with the knowledge and skills to undertake such projects.MethodsEight nurses from five burns services across Malawi and Ethiopia took part in this pilot course, which was evaluated using a range of methods, including interviews and focus group discussions.ResultsCourse evaluations reported that interactive activities were successful in supporting participants to devise QI projects. Appropriate online platforms were integral to creating a community of practice and maintaining engagement. Facilitators to a successful QI project were active individuals, supportive leadership, collaboration, effective knowledge sharing and demonstrable advantages of any proposed change. Barriers included: staff attitudes, poor leadership, negative culture towards training, resource limitations, staff rotation and poor access to information to guide practice.ConclusionsThe course demonstrated that by bringing nurses together, through interactive teaching and online forums, a supportive community of practice can be created. Future work will include investigating ways to scale up access to the course so staff can be supported to initiate and lead quality improvement in LMIC burn services. 相似文献
69.
70.
The presence of pesticides in the Israeli food supply is well documented but little is known about the risks posed by children's diets for potential exposures. We investigated potential exposures to food-borne pesticides in a sample of 301 urban Israeli children (2008–10). Data from a food frequency questionnaire, 24 hour food recall, and Israel's national pesticide monitoring program were used to estimate uptake factors for 26 compounds in 27 fruits and vegetables. A pilot risk assessment was performed and the findings were compared with the Israel Ministry of Health's 2012 pesticide risk assessment for the general population. The surveyed children had higher potential exposures than the general population for over one third of the compounds, and uptake factors exceeded the Acceptable Daily Intake in ten compounds. Methamidophos, exceeded the ADI at the 25th percentile and fenamiphos, iprodione, and oxydemethon methyl, exceeded the ADI at the 50 percentile. ADIs for several compounds were exceeded even though the residues detected were below the statutory limit. Improved monitoring, enforcement, and revision of the Maximum Residue Limit for certain food/pesticide pairs are indicated as is the need to incorporate data on children's actual food consumption in national risk assessments. 相似文献