全文获取类型
收费全文 | 14574篇 |
免费 | 1154篇 |
国内免费 | 33篇 |
专业分类
耳鼻咽喉 | 162篇 |
儿科学 | 559篇 |
妇产科学 | 353篇 |
基础医学 | 1980篇 |
口腔科学 | 578篇 |
临床医学 | 2118篇 |
内科学 | 2628篇 |
皮肤病学 | 208篇 |
神经病学 | 1343篇 |
特种医学 | 247篇 |
外国民族医学 | 2篇 |
外科学 | 1119篇 |
综合类 | 153篇 |
一般理论 | 18篇 |
预防医学 | 2183篇 |
眼科学 | 309篇 |
药学 | 850篇 |
中国医学 | 44篇 |
肿瘤学 | 907篇 |
出版年
2024年 | 21篇 |
2023年 | 167篇 |
2022年 | 228篇 |
2021年 | 462篇 |
2020年 | 348篇 |
2019年 | 510篇 |
2018年 | 532篇 |
2017年 | 425篇 |
2016年 | 399篇 |
2015年 | 456篇 |
2014年 | 603篇 |
2013年 | 878篇 |
2012年 | 1205篇 |
2011年 | 1248篇 |
2010年 | 647篇 |
2009年 | 545篇 |
2008年 | 931篇 |
2007年 | 988篇 |
2006年 | 862篇 |
2005年 | 756篇 |
2004年 | 713篇 |
2003年 | 642篇 |
2002年 | 599篇 |
2001年 | 139篇 |
2000年 | 101篇 |
1999年 | 91篇 |
1998年 | 115篇 |
1997年 | 84篇 |
1996年 | 78篇 |
1995年 | 68篇 |
1994年 | 70篇 |
1993年 | 41篇 |
1992年 | 58篇 |
1991年 | 62篇 |
1990年 | 33篇 |
1989年 | 41篇 |
1988年 | 36篇 |
1987年 | 28篇 |
1986年 | 28篇 |
1985年 | 27篇 |
1984年 | 37篇 |
1983年 | 25篇 |
1982年 | 27篇 |
1981年 | 26篇 |
1980年 | 31篇 |
1979年 | 14篇 |
1978年 | 15篇 |
1977年 | 21篇 |
1976年 | 25篇 |
1968年 | 15篇 |
排序方式: 共有10000条查询结果,搜索用时 984 毫秒
11.
Maria C. Chammas Andre C. Oliveira Mario J. D´Ávilla Pedro H. Moraes Marcelo Straus Takahashi 《Ultrasound in medicine & biology》2019,45(1):50-55
We prospectively evaluated the effectiveness of contrast-enhanced ultrasonography (CEUS) for differentiation of benign versus malignant portal vein thrombosis (PVT). We studied a total of 43 patients with chronic liver disease, hepatocellular carcinoma-suggestive nodules and confirmed PVT, in whom the nature of the PVT was confirmed by follow-up imaging (US, computed tomography and/or magnetic resonance imaging) performed up to 6 mo after CEUS. PVT was assessed by US, Doppler US and CEUS with respect to vessel wall disruption and/or invasion, color Doppler vascularization, pulsed Doppler vascularization pattern and CEUS enhancement and vascularization pattern, and thrombi were classified as benign or malignant based on these findings. Follow-up studies revealed malignant PVT in 22 of the 43 patients (51%) and benign PVT in 21 patients (49%). CEUS findings were consistent with follow-up studies in 41 of the 43 patients (95%), with κ?=?0.903 (p < 0.0001), sensitivity?=?91% and specificity?=?100%, indicating that CEUS can be confidently used to differentiate benign from malignant portal vein thrombosis in the setting of chronic liver disease. 相似文献
12.
13.
Abstract: Background: Identification of risk drinking in expectant fathers may be helpful as an important part of efforts to minimize maternal alcohol use, and as an opportunity to inform them about a problematic practice during a critical developmental stage for the couple. The purpose of this study was to evaluate the T‐ACE screening questionnaire, which asks about t olerance to alcohol, being a nnoyed by other's comments about drinking, attempts to c ut down, and having a drink first thing in the morning (“ e ye‐opener”), in the male partners of pregnant women who themselves were T‐ACE positive. Methods: Two hundred fifty‐four male partners were asked to complete the T‐ACE embedded in a health survey, the Alcohol Use Disorders Identification Test (AUDIT), and other questions about their alcohol use in the past 30 days when their pregnant partners had a median gestation of 11.5 weeks (T1). After delivery, male partners again completed the T‐ACE and quantity‐frequency questions (T2). The predictive ability of the T‐ACE and AUDIT was compared, using risk drinking (>4 drinks/day or >14 drinks/week) as the criterion standard. Results: A substantial minority of male partners had risk drinking, 31 percent at T1 and 25 percent at T2. Although the AUDIT was better than the T‐ACE as an independent predictor of risk drinking, the latter was most accurate when the tolerance threshold exceeded 2 drinks, the same established for pregnant women. The sensitivity (T1 = 84.6%, T2 = 82.8%) and specificity (T1 = 43.8%, T2 = 51.1%) of the T‐ACE at this threshold compared favorably with those of the AUDIT at the standard cut point of 8. Conclusions: The T‐ACE may be a practical way for clinicians to identify risk drinking in both pregnant women and expectant fathers. (BIRTH 33:2 June 2006) 相似文献
14.
Louise Arnold 《Academic medicine》2002,77(6):502-515
PURPOSE: The author interprets the state of the art of assessing professional behavior. She defines the concept of professionalism, reviews the psychometric properties of key approaches to assessing professionalism, conveys major findings that these approaches produced, and discusses recommendations to improve the assessment of professionalism. METHOD: The author reviewed professionalism literature from the last 30 years that had been identified through database searches; included in conference proceedings, bibliographies, and reference lists; and suggested by experts. The cited literature largely came from peer-reviewed journals, represented themes or novel approaches, reported qualitative or quantitative data about measurement instruments, or described pragmatic or theoretical approaches to assessing professionalism. RESULTS: A circumscribed concept of professionalism is available to serve as a foundation for next steps in assessing professional behavior. The current array of assessment tools is rich. However, their measurement properties should be strengthened. Accordingly, future research should explore rigorous qualitative techniques; refine quantitative assessments of competence, for example, through OSCEs; and evaluate separate elements of professionalism. It should test the hypothesis that assessment tools will be better if they define professionalism as behaviors expressive of value conflicts, investigate the resolution of these conflicts, and recognize the contextual nature of professional behaviors. Whether measurement tools should be tailored to the stage of a medical career and how the environment can support or sabotage the assessment of professional behavior are central issues. FINAL THOUGHT: Without solid assessment tools, questions about the efficacy of approaches to educating learners about professional behavior will not be effectively answered. 相似文献
15.
Bartczak Andi Weiss; Sangaiah Ramiah; Ball Louise M.; Warren Sarah H.; Gold Avram 《Mutagenesis》1987,2(2):101-105
Many polycyclic aromatic hydrocarbons containing peripherallyfused cyclopenta rings are believed to be activated primarilyby epoxidation of the cyclopenta ring. The cyclopenta epoxidesof a series of four cyclopenta benzanthracene derivatives, benz[e]aceanthrylene-5,6-oxide,benz[j]ace-anthrylene-1,2-oxide, benz(l)anthrylene-1,2-oxideand benz[k]acephenaceanthrylene-4,5-oxide were synthesized fromtheir parent hydrocarbons by formation of the bromohydrin followedby dehydrobromination, and characterized by u.v. vis,and 1H n.m.r. spectroscopy and mass spectrometry. The mutagenicityof these compounds was investigated in the Ames plate incorporationassay with Salmonella typhimurium strain TA98. All the oxideswere active without exogenous metabolic activation (170320His+ revertants per nanomole) and also toxic above 0.5 µg/plate.Addition of S9 protein did not increase, and generally decreased,the mutagenicity of the oxides, while toxicity was largely unchanged.These results are consistent with the postulated role of cyclopentaoxides as major contributors to the mutagenicity of the parentcompounds in the Ames assay. 相似文献
16.
17.
18.
19.
Jens O L J?rgensen Louise M?ller Morten Krag Nils Billestrup Jens S Christiansen 《Endocrinology & Metabolism Clinics of North America》2007,36(1):75-87
This article focuses on in vivo data from tests performed in normal subjects and in patients who had abnormal growth hormone (GH) status. Experimental data in human subjects demonstrate that GH acutely inhibits glucose disposal in skeletal muscle. At the same time GH stimulates the turnover and oxidation of free fatty acid (FFA), and experimental evidence suggests a causal link between elevated FFA levels and insulin resistance in skeletal muscle. Observational data in GH-deficient adults do not indicate that GH replacement is associated with significant impairment of glucose tolerance, but it is recommended that overdosing be avoided and glycemic control be monitored. 相似文献
20.
Phospho-akt expression is associated with a favorable outcome in non-small cell lung cancer. 总被引:3,自引:0,他引:3
Amit Shah William A Swain Donna Richardson John Edwards Duncan J Stewart Catherine M Richardson Daniel E B Swinson Dipika Patel J Louise Jones Kenneth J O'Byrne 《Clinical cancer research》2005,11(8):2930-2936
Akt, a Serine/Threonine protein kinase, mediates growth factor-associated cell survival. Constitutive activation of Akt (phosphorylated Akt, P-Akt) has been observed in several human cancers, including lung cancer and may be associated with poor prognosis and chemotherapy and radiotherapy resistance. The clinical relevance of P-Akt in non-small cell lung cancer (NSCLC) is not well described. In the present study, we examined 82 surgically resected snap-frozen and paraffin-embedded stage I to IIIA NSCLC samples for P-Akt and Akt by Western blotting and for P-Akt by immunohistochemistry. P-Akt protein levels above the median, measured using reproducible semiquantitative band densitometry, correlated with a favorable outcome (P = 0.007). Multivariate analysis identified P-Akt as a significant independent favorable prognostic factor (P = 0.004). Although associated with a favorable prognosis, high P-Akt levels correlated with high tumor grade (P = 0.02). Adenocarcinomas were associated with low P-Akt levels (P = 0.039). Akt was not associated with either outcome or clinicopathologic variables.Cytoplasmic (CP-Akt) and nuclear (NP-Akt) P-Akt tumor cell staining was detected in 96% and 42% of cases, respectively. Both CP-Akt and NP-Akt correlated with well-differentiated tumors (P = 0.008 and 0.017, respectively). NP-Akt also correlated with nodal metastases (P = 0.022) and squamous histology (P = 0.037).These results suggest P-Akt expression is a favorable prognostic factor in NSCLC. Immunolocalization of P-Akt, however, may be relevant as NP-Akt was associated with nodal metastases, a known poor prognostic feature in this disease. P-Akt may be a potential novel therapeutic target for the management of NSCLC. 相似文献