全文获取类型
收费全文 | 3526篇 |
免费 | 218篇 |
国内免费 | 26篇 |
专业分类
耳鼻咽喉 | 18篇 |
儿科学 | 110篇 |
妇产科学 | 67篇 |
基础医学 | 581篇 |
口腔科学 | 64篇 |
临床医学 | 290篇 |
内科学 | 736篇 |
皮肤病学 | 57篇 |
神经病学 | 430篇 |
特种医学 | 53篇 |
外科学 | 460篇 |
综合类 | 25篇 |
一般理论 | 7篇 |
预防医学 | 397篇 |
眼科学 | 53篇 |
药学 | 153篇 |
中国医学 | 5篇 |
肿瘤学 | 264篇 |
出版年
2024年 | 5篇 |
2023年 | 56篇 |
2022年 | 85篇 |
2021年 | 139篇 |
2020年 | 79篇 |
2019年 | 103篇 |
2018年 | 99篇 |
2017年 | 80篇 |
2016年 | 97篇 |
2015年 | 133篇 |
2014年 | 163篇 |
2013年 | 206篇 |
2012年 | 276篇 |
2011年 | 299篇 |
2010年 | 151篇 |
2009年 | 147篇 |
2008年 | 206篇 |
2007年 | 204篇 |
2006年 | 240篇 |
2005年 | 221篇 |
2004年 | 208篇 |
2003年 | 167篇 |
2002年 | 141篇 |
2001年 | 14篇 |
1999年 | 15篇 |
1998年 | 25篇 |
1997年 | 16篇 |
1996年 | 18篇 |
1995年 | 15篇 |
1994年 | 16篇 |
1993年 | 14篇 |
1992年 | 9篇 |
1991年 | 7篇 |
1989年 | 4篇 |
1988年 | 4篇 |
1987年 | 5篇 |
1986年 | 5篇 |
1985年 | 4篇 |
1984年 | 10篇 |
1983年 | 5篇 |
1982年 | 6篇 |
1981年 | 3篇 |
1980年 | 3篇 |
1978年 | 6篇 |
1977年 | 4篇 |
1976年 | 4篇 |
1975年 | 3篇 |
1972年 | 3篇 |
1965年 | 3篇 |
1945年 | 4篇 |
排序方式: 共有3770条查询结果,搜索用时 15 毫秒
51.
Andreas Ch. Lazaris M.D. Panagiotis Davaris M.D. Lydia Nakopoulou M.D. George E. Theodoropoulos M.D. George Koullias M.D. Basil Ch. Golematis M.D. 《Diseases of the colon and rectum》1994,37(11):1083-1089
PURPOSE: Proliferating cell nuclear antigen immunohistochemical expression and flow cytometry techniques were used in this study to estimate the proliferation tendency and biologic aggressiveness in benign and malignant epithelial tumors of the colon and rectum. METHODS: Thirty-five adenomas and 60 adenocarcinomas were studied immunohistochemically concerning proliferating cell nuclear antigen positivity in tumor cell nuclei. In addition, flow cytometry techniques were used to estimate the DNA content and percentage of tumor cells in the S-phase. RESULTS: The mean proliferating cell nuclear antigen score for adenomas was 38 percent compared with a mean score of 50.4 percent for adenocarcinomas that were studied (P <0.05). In dysplastic areas of malignantly transformed adenomas (n=5), the highest proliferating cell nuclear antigen score (80 percent) was focally observed. Taking flow cytometry parameters into account, we found out that proliferating cell nuclear antigen can be used as an indirect indicator of the number of cells in the S-phase (SPF) but not as an independent prognostic factor. Statistical significance was found between Type III (aneuploid carcinomas) and increased proliferating cell nuclear antigen expression (proliferating cell nuclear antigen score ? 60 percent). Furthermore, aneuploidy was especially found on cancer located on the left colon (44 percent vs. 14 percent of right colon neoplasms). Considering DNA ploidy of the above neoplasms, the aneuploid adenocarcinomas had a tendency for poorer prognosis especially if they were related to Dukes Stage C female patients. CONCLUSIONS: The comparative assessment of the above parameters might be of considerable importance in the study of the proliferation activity of any form of colorectal neoplasia. 相似文献
52.
Franziska Albers Lydia Wachsmuth Timo Mauritz van Alst Cornelius Faber 《Molecular imaging and biology》2018,20(2):171-182
Recent developments of optogenetic tools and fluorescence-based calcium recording techniques enable the manipulation and monitoring of neural circuits on a cellular level. Non-invasive imaging of brain networks, however, requires the application of methods such as blood oxygen level-dependent (BOLD) functional magnetic resonance imaging (fMRI), which is commonly used for functional neuroimaging. While BOLD fMRI provides brain-wide non-invasive reading of the hemodynamic response, it is only an indirect measure of neural activity. Direct observation of neural responses requires electrophysiological or optical methods. The latter can be combined with optogenetic control of neuronal circuits and are MRI compatible. Yet, simultaneous optical recordings are still limited to fiber-optic-based approaches. Here, we review the integration of optical recordings and optogenetic manipulation into fMRI experiments. As a practical example, we describe how BOLD fMRI in a 9.4-T small animal MR scanner can be combined with in vivo fiber-optic calcium recordings and optogenetic control in a multimodal setup. We present simultaneous BOLD fMRI and calcium recordings under optogenetic control in rat. We outline details about MR coil configuration, choice, and usage of opsins and chemically and genetically encoded calcium sensors, fiber implantation, appropriate light power for stimulation, and calcium signal detection, to provide a glimpse into challenges and opportunities of this multimodal molecular neuroimaging approach. 相似文献
53.
Charles A. Austin Summer Choudhury Taylor Lincoln Lydia H. Chang Christopher E. Cox Mark A. Weaver Laura C. Hanson Judith E. Nelson Shannon S. Carson 《Journal of pain and symptom management》2018,55(3):946-952
Context
Patients triggering rapid response team (RRT) intervention are at high risk for adverse outcomes. Data on symptom burden of these patients do not currently exist, and current symptom management and communication practices of RRT clinicians are unknown.Objectives
We sought to identify the symptom experience of RRT patients and observe how RRT clinicians communicate with patients and their families.Methods
We conducted a prospective observational study from August to December 2015. Investigators attending RRT events measured frequencies of symptom assessment, communication, and supportive behaviors by RRT clinicians. As the rapid response event concluded, investigators measured patient-reported pain, dyspnea, and anxiety using a numeric rating scale of 0 (none) to 10 (most severe), with uncontrolled symptoms defined as numeric rating scale score of ≥4.Results
We observed a total of 52 RRT events. RRT clinicians assessed for pain during the event in 62% of alert patients, dyspnea in 38%, and anxiety in 21%. Goals of care were discussed during 3% of events and within 24 hours in 13%. For the primary outcome measure, at the RRT event conclusion, 44% of alert patients had uncontrolled pain, 39% had uncontrolled dyspnea, and 35% had uncontrolled anxiety.Conclusion
Hospitalized patients triggering RRT events have a high degree of uncontrolled symptoms that are infrequently assessed and treated. Although these patients experience an acute change in medical status and are at high risk for adverse outcomes, goals-of-care discussions with RRT patients or families are rarely documented in the period after the events. 相似文献54.
55.
B. Joseph Elmunzer Rebecca L. Spitzer Lydia D. Foster Ambreen A. Merchant Eric F. Howard Vaishali A. Patel Mary K. West Emad Qayed Rosemary Nustas Ali Zakaria Marc S. Piper Jason R. Taylor Lujain Jaza Nauzer Forbes Millie Chau Luis F. Lara Georgios I. Papachristou Michael L. Volk Valerie Durkalski 《Clinical gastroenterology and hepatology》2021,19(7):1355-1365.e4
56.
Leticia Leon Lydia Abasolo Benjamin Fernandez-Gutierrez Juan Angel Jover Cesar Hernandez-Garcia 《Reumatología clinica》2018,14(1):4-8
Objective
To analyze the resource utilization in rheumatoid arthritis (RA) patients and predictive factors in and patients treated with biological drugs and biologic-naïve.Methods
A cross-sectional study was performed in a sample including all regions and hospitals throughout the country. Sociodemographic data, disease activity parameters and treatment data were obtained. Resource utilization for two years of study was recorded and we made costs imputation. Correlation analyzes were performed on all RA patients and those treated with biological and biological naïve, to estimate the differences in resource utilization. Factors associated with increased resources utilization (costs) attending to treatment was analyzed by linear regression models.Results
We included 1,095 RA patients, 26% male, mean age of 62 ± 14 years. Mean of direct medical costs per patient was €24,291 ± €45,382. Excluding biological drugs, the average cost per patient was €3,742 ± €3,711. After adjustment, factors associated with direct medical costs for all RA patients were biologic drugs (P = .02) and disease activity (P = .004). In the biologic-naïve group, the predictor of direct medical costs was comorbidity (P < .001). In the biologic treatment group predictors were follow-up length of the disease (P = .04), age (P = .02) and disease activity (P = .007).Conclusion
Our data show a remarkable economic impact of RA. It is important to identify and estimate the economic impact of the disease, compare data from other geographic samples and to develop improvement strategies to reduce these costs and increase the quality of care. 相似文献57.
Virtanen I Korhonen M Petäjäniemi N Karhunen T Thornell LE Sorokin LM Konttinen YT 《The Journal of clinical endocrinology and metabolism》2003,88(10):4960-4966
Laminin has been proposed to influence the function of human adrenal cortex. We have studied the distribution of laminin (Ln) chains using immunofluorescence in human fetal and adult adrenal cortex. In the fetal gland Ln alpha2- and alpha5-chains were weakly expressed in the definitive zone, whereas Ln alpha4-, beta1-, and gamma1-chains occurred around vessels. In the adult gland, Ln alpha2-, alpha5-, and gamma1-chains were found in epithelial basement membranes (BM) in all cortical zones, Ln alpha4-chain in vessels, Ln beta1-chain in outer zone, and Ln beta2-chain in the two inner zones of the cortex, respectively. Among the integrins in adult gland, integrin alpha(3)-subunit was confined to basal surfaces of cortical cells, alpha(6) to vessels, alpha(1) to the stroma, and alpha(2) diffusely to epithelial cells. Lutheran glycoprotein and dystroglycan occurred in the fetal gland diffusely in the definitive zone and throughout the epithelium in the adult. The isoform composition of BM of the adult adrenal gland is distinct, with Ln-2 and -10 in BM of the outer zone and Ln-4 and -11 in BM of the two inner zones. The results suggest that integrin alpha(3)beta(1) and Lutheran are candidate receptors for Ln-10 and -11, whereas dystroglycan probably binds Ln-2 and -4. 相似文献
58.
59.
Romina Lomonaco Eddison Godinez Leiva Fernando Bril Sulav Shrestha Lydia Mansour Jeff Budd Jessica Portillo Romero Siegfried Schmidt Ku-Lang Chang George Samraj John Malaty Katherine Huber Pierre Bedossa Srilaxmi Kalavalapalli Jonathan Marte Diana Barb Danielle Poulton Nada Fanous Kenneth Cusi 《Diabetes care》2021,44(2):399
OBJECTIVEAssess the prevalence of nonalcoholic fatty liver disease (NAFLD) and of liver fibrosis associated with nonalcoholic steatohepatitis in unselected patients with type 2 diabetes mellitus (T2DM).RESEARCH DESIGN AND METHODSA total of 561 patients with T2DM (age: 60 ± 11 years; BMI: 33.4 ± 6.2 kg/m2; and HbA1c: 7.5 ± 1.8%) attending primary care or endocrinology outpatient clinics and unaware of having NAFLD were recruited. At the visit, volunteers were invited to be screened by elastography for steatosis and fibrosis by controlled attenuation parameter (≥274 dB/m) and liver stiffness measurement (LSM; ≥7.0 kPa), respectively. Secondary causes of liver disease were ruled out. Diagnostic panels for prediction of advanced fibrosis, such as AST-to-platelet ratio index (APRI) and Fibrosis-4 (FIB-4) index, were also measured. A liver biopsy was performed if results were suggestive of fibrosis.RESULTSThe prevalence of steatosis was 70% and of fibrosis 21% (LSM ≥7.0 kPa). Moderate fibrosis (F2: LSM ≥8.2 kPa) was present in 6% and severe fibrosis or cirrhosis (F3–4: LSM ≥9.7 kPa) in 9%, similar to that estimated by FIB-4 and APRI panels. Noninvasive testing was consistent with liver biopsy results. Elevated AST or ALT ≥40 units/L was present in a minority of patients with steatosis (8% and 13%, respectively) or with liver fibrosis (18% and 28%, respectively). This suggests that AST/ALT alone are insufficient as initial screening. However, performance may be enhanced by imaging (e.g., transient elastography) and plasma diagnostic panels (e.g., FIB-4 and APRI).CONCLUSIONSModerate-to-advanced fibrosis (F2 or higher), an established risk factor for cirrhosis and overall mortality, affects at least one out of six (15%) patients with T2DM. These results support the American Diabetes Association guidelines to screen for clinically significant fibrosis in patients with T2DM with steatosis or elevated ALT. 相似文献