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   5900篇
  免费   351篇
  国内免费   66篇
耳鼻咽喉   64篇
儿科学   140篇
妇产科学   63篇
基础医学   780篇
口腔科学   70篇
临床医学   343篇
内科学   1683篇
皮肤病学   63篇
神经病学   414篇
特种医学   234篇
外科学   1117篇
综合类   20篇
预防医学   175篇
眼科学   88篇
药学   295篇
中国医学   3篇
肿瘤学   765篇
  2024年   5篇
  2023年   46篇
  2022年   126篇
  2021年   212篇
  2020年   120篇
  2019年   153篇
  2018年   215篇
  2017年   157篇
  2016年   195篇
  2015年   197篇
  2014年   247篇
  2013年   286篇
  2012年   487篇
  2011年   456篇
  2010年   280篇
  2009年   224篇
  2008年   359篇
  2007年   310篇
  2006年   335篇
  2005年   324篇
  2004年   309篇
  2003年   318篇
  2002年   291篇
  2001年   54篇
  2000年   37篇
  1999年   63篇
  1998年   80篇
  1997年   68篇
  1996年   55篇
  1995年   47篇
  1994年   29篇
  1993年   36篇
  1992年   29篇
  1991年   29篇
  1990年   22篇
  1989年   10篇
  1988年   9篇
  1987年   9篇
  1986年   8篇
  1985年   10篇
  1984年   10篇
  1983年   9篇
  1982年   12篇
  1981年   10篇
  1980年   7篇
  1979年   3篇
  1977年   4篇
  1976年   3篇
  1975年   3篇
  1974年   3篇
排序方式: 共有6317条查询结果,搜索用时 15 毫秒
61.
Objective To examine the continuation of antibody prevalence status after 12 months and background factors in antibody-positive subjects following asymptomatic infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Methods We initially determined the SARS-CoV-2 anti-nucleocapsid protein immunoglobulin G (anti-N IgG) antibody prevalence in 1,603 patients, doctors, and nurses at 65 medical institutions in Kanagawa Prefecture, Japan. We then obtained consent from 33 of the 39 subjects who tested positive and performed follow-up for 12 months. Results Follow-up for up to 12 months showed that a long-term response of the anti-N IgG antibody could be detected in 6 of the 33 participants (18.2%). The proportions with hypertension, using an angiotensin-receptor blocker, and without a drinking habit were higher among the participants with a long-term anti-N IgG antibody response for up to 12 months than among those without a long-term antibody response. Conclusions The proportion of individuals with subclinical COVID-19 who continuously had a positive result for the anti-N IgG antibody at 12 months was low.  相似文献   
62.
OBJECT: The effects of percutaneous transluminal angioplasty (PTA) and stent placement for stenosis of the petrous or cavernous portion of the internal carotid artery (ICA) were compared. METHODS: Twenty-four patients with symptomatic, greater than 60% stenosis of the petrous or cavernous portion of the ICA were treated using PTA or stent placement; 15 were treated with PTA and nine with stent insertion. Initial and follow-up results (> 3 months posttreatment) were compared in each group. Stenotic portions of the ICA were successfully opened in 13 of 15 patients in the PTA group, and in all nine patients in the stent-treated group. In one case in the PTA group stent delivery was attempted; however, the device could not pass through the vessel's tortuous curve, and PTA alone was performed in this case. Postoperatively, the mean stenotic ratio decreased from 72.1 to 29.6% in the PTA group, and from 75.6 to 2.2% in the stent-treated group. In four patients in the PTA group, stenoses greater than 50% were demonstrated on follow-up angiography performed at 3 to 6 months after PTA. In the stent-treated group, no restenosis was encountered, although in one case acute occlusion of the stent occurred; the device was recanalized with PTA and infusion of tissue plasminogen activator. This case was the only one of the 24 in which any neurological deficits related to the endovascular procedure occurred. Stent placement brought a greater gain in diameter than did PTA at the initial and late follow-up period; this gain was statistically significant. CONCLUSIONS: Stent placement is more effective than PTA for stenosis of the petrous or cavernous portion of the ICA from the viewpoint of initial and late gain in diameter.  相似文献   
63.
Purpose. To demonstrate the utilities of a synthetic low-affinity ligand ((Gal)3) for the asialoglycoprotein receptor (ASGP-R) as a hepatic targeting device for therapeutic cytokines. Methods. The site-specific incorporation of (Gal)3 or a typical high-affinity ligand (GalNAc)3 into IL-2 was catalyzed by microbial transglutaminase. The anti-tumor activities, pharmacokinetic profiles and receptor-mediated endocytosis in hepatocytes of the ligand-IL-2 conjugates were examined in mouse. Results. The (Gal)3 has approximately 50 times lower affinity to ASGP-R than (GalNAc)3. Nevertheless, the antitumor effects were in the order of (Gal)3—IL-2 > unmodified IL-2 > (GalNAc)3—IL-2. The systemic elimination and the hepatic uptake of (GalNAc)3—IL-2 were more rapid than (Gal)3—IL-2. The ratio of the rate constant representing dissociation from the cell-surface receptor (koff) to that representing endocytosis of the ligand (kint) was greater for (Gal)3—IL-2 than (GalNAc)3—IL-2, suggesting that (Gal)3—IL-2 preferably avoids internalization due to its lower affinity to the receptor. The simulation studies demonstrated that (Gal)3—IL-2 was present in the hepatic extracellular space for a longer period than (GalNAc)3 IL-2. Conclusions. The (Gal)3 ligand increases the therapeutic efficacy of IL-2 by enhancing its exposure to the cell-surface. The koff/kint affects the targeting efficacy of the conjugates to ASGP-R.  相似文献   
64.
Central nervous system methotrexate-associated lymphoproliferative disorder (CNS-MTX-LPD) is rare, but its spontaneous regression has been observed in some patients after withdrawal of agents. We herein report three cases of primary CNS-MTX-LPD that received oral MTX for rheumatoid arthritis. Epstein-Barr virus and oligoclonal bands (OCBs) were positive, while proton magnetic resonance spectroscopy (1H-MRS) showed an elevated lipid peak and slightly elevated choline/N-acetylaspartate ratio in common. After MTX withdrawal, brain lesions showed spontaneous regression in all cases. Our patient''s 1H-MRS findings and OCBs may reflect a non-monoclonal lymphoproliferative histology as benign-type lesions in CNS-MTX-LPD.  相似文献   
65.
BackgroundAlveolar air leakage from a pleural defect around the staple line is one of the complications after wedge resection of the lung. An intraoperative closure of the pleural defect by suturing can cause additional pleural rupture due to tension of the pleura adjacent to staple lines. Therefore, we have introduced a novel closure method for pleural defect adjacent to the staple line, named the double stapling method. This study compared the efficacy of two closure methods; the double stapling method and conventional suturing method with pledgets using ex vivo porcine lungs.MethodsThe double stapling method involves closing the pleural defect by suturing the two parallel staple lines at both sides of the pleural defect. This method was developed to distribute the pleural tension around the needle holes of suturing. As a model of pleural defect adjacent to the staple line after wedge resection, wedge resection of the caudal lobe of left porcine lungs was performed, and a superficial square pleural defect (10 mm × 10 mm) adjacent to the staple line was made by scalpel. The defect was closed using the following two methods: (I) suturing with pledgets (n=10); and (II) double stapling method (n=10). The lobe was inflated in water at an airway pressure of 20, 25, and 30 cmH2O; closure success or failure was judged by the absence or presence of air leakage.ResultsThe closure success was confirmed in 2 (20%) out of 10 cases in the suturing with pledgets group and 9 (90%) out of 10 in the double stapling method group (P=0.007). In 4 out of 10 cases in the suturing with pledgets group, new pleural clefts longer than 3 mm were created around the needle holes of suturing.ConclusionsEx vivo experiments have suggested the superiority of the double stapling method for the intraoperative closure of alveolar air leakage adjacent to the staple line after wedge resection, compared to conventional suturing with the pledget method.  相似文献   
66.
Objective Coronavirus disease (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has spread globally. Although the relationship between anti-SARS-CoV-2 immunoglobulin G (IgG) antibodies and COVID-19 severity has been reported, information is lacking regarding the seropositivity of patients with particular types of diseases, including hematological diseases. Methods In this single-center, retrospective study, we compared SARS-CoV-2 IgG positivity between patients with hematological diseases and those with non-hematological diseases. Results In total, 77 adult COVID-19 patients were enrolled. Of these, 30 had hematological disorders, and 47 had non-hematological disorders. The IgG antibody against the receptor-binding domain of the spike protein was detected less frequently in patients with hematological diseases (60.0%) than in those with non-hematological diseases (91.5%; p=0.029). Rituximab use was significantly associated with seronegativity (p=0.010). Conclusion Patients with hematological diseases are less likely to develop anti-SARS-CoV-2 antibodies than those with non-hematological diseases, which may explain the poor outcomes of COVID-19 patients in this high-risk group.  相似文献   
67.
Diacylglycerol kinase (DGK) metabolizes diacylglycerol (DG), a glycerolipid containing two acyl chains, to convert phosphatidic acid. DG is produced through phosphoinositide turnover within the membrane and is well known to act as a second messenger that modulates the activity of protein kinase C in the cellular signal transduction. Recent studies have revealed that DG also activates several proteins, including Ras guanine-nucleotide releasing protein and ion channels such as transient receptor potential proteins. Therefore, DGK is thought to participate in a number of signaling cascades by modulating levels of DG. Previous studies have disclosed that DGK is composed of a family of the isozymes, which differ in the structure, enzymological property, gene expression and localization, subcellular localization, and binding molecules. The present review focuses on the stories of phosphoinositide turnover and DG, including historical views, structural features, metabolism, and relevant cellular phenomena, together with the characteristics of DGK isozymes and the pathophysiological findings on animal studies using knockout mice and models for human diseases. Now it is being revealed that the structural and functional diversity and heterogeneity of and around DGK support the proper arrangement of the complex signal transduction machinery.  相似文献   
68.
The functional support and advancement of our body while preserving inherent naturalness is one of the ultimate goals of bioengineering. Skin protection against infectious pathogens is an application that requires common and long-term wear without discomfort or distortion of the skin functions. However, no antimicrobial method has been introduced to prevent cross-infection while preserving intrinsic skin conditions. Here, we propose an antimicrobial skin protection platform copper nanomesh, which prevents cross-infectionmorphology, temperature change rate, and skin humidity. Copper nanomesh exhibited an inactivation rate of 99.99% for Escherichia coli bacteria and influenza virus A within 1 and 10 min, respectively. The thin and porous nanomesh allows for conformal coating on the fingertips, without significant interference with the rate of skin temperature change and humidity. Efficient cross-infection prevention and thermal transfer of copper nanomesh were demonstrated using direct on-hand experiments.

The functional support and advancement of our body while preserving the inherent naturalness is one of the ultimate goals of bioengineering (14). A functional layer is placed on the skin to complement the intrinsic biological and interactive functions (5, 6) and to add functions that do not yet exist (79). During use, the second skin layer should completely exploit its function and underlay skin functions without deforming the skin or interfering with the skin’s external interaction. Materials and structures need to be conformal and mechanically similar to the skin to minimize the distortion of natural sensations and movements. In addition, the air and heat transfer on the skin must be unimpeded to obtain a natural and comfortable wear fit (10).Body protection that requires common and long-term wear is an application in which both functionality and naturalness are important. As the outermost layer connecting our body to the environment, the skin is exposed to physical damage, hazardous chemicals, and infectious pathogens (11, 12). Therefore, we add a protective layer on the skin that blocks or filters out external contaminants. This entails the isolation and accumulation of biochemical compounds, which can lead to self-contamination and the subsequent cross-contamination/infection by interacting with other objects. In contrast to chemical contamination, which is not self-reproductive, the biological contamination of infectious microbes, such as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is a considerable issue to be addressed.By containing an antimicrobial material on the surface of the skin protective layer, cross-infection can be prevented in the long term. Unlike temporary rinsing or disinfection, the use of antibacterial or antiviral substances such as chemical or natural disinfectants and metal nanomaterials inhibits the growth of microorganisms on the surface (1317). These materials are embedded in a complete covering polymer layer, such as gloves (18, 19), to isolate and protect both the inner and outer surfaces from the infection. To add breathability to the textile especially for the mask (13, 20, 21), many antibacterial fibers have been developed based on these materials. Moreover, various skin-attachable platforms with antimicrobial properties have been developed for convenient usage in daily lives. Antimicrobial nanofibers with conformal attachment to the skin have been developed for drug delivery, wound healing (22, 23), and electrophysiology (24, 25). In addition, stretchable and antibacterial hydrogels have been developed to allow more natural skin movement in wound-healing applications (2628).However, there has been no practical skin protective solution to prevent cross-infection while preserving intrinsic skin conditions such as surface morphology, thermal transfer, and skin humidity. The thickening of the additional skin layer frequently results in a significant modification of the surface morphology, heat transfer, and the corresponding sensation. Thin layers have limited performance in terms of antimicrobial duration and speed. The skin coverage of polymer or hydrogel film blocks the transfer of air, moisture, and heat. In addition, the antimicrobial performance is focused on the skin side rather than the external side that affects cross-infection. Voids owing to the stiffness of the film or fiber and morphological differences compared to the skin further limit conformality, heat transfer, and water/air permeability (29).Here, we propose an antimicrobial skin protection platform copper nanomesh, which prevents cross-infection while minimizing modification of intrinsic skin properties such as interfacial morphology, temperature change rate, and skin humidity. The thin thickness and porous structure of the nanomesh allow conformal attachment to the fingertips, regardless of the mechanical and structural variations of the fingerprints, nails, and interfaces. To impart antimicrobial properties, copper, one of the most well-known antimicrobial (nano)materials (3033), was coated with maintaining the nanomesh structure (copper nanomesh, from here onward). The measured inactivation rates of copper nanomesh against Escherichia coli bacteria and influenza virus A (H1N1) were 99.99% within 1 min and 10 min, respectively. It was found that the nanomesh structure contributed to the acceleration of bacterial inactivation compared to the copper film. Furthermore, it exhibited high biocompatibility with the skin cells and stable antibacterial performance even after long-term use (more than 6 h), including water immersion (more than 1 h).In addition, we investigated the naturalness of the copper nanomesh compared to that of the copper film and conventional gloves. As confirmed using the artificial skin and fingerprint recognition, the proposed copper nanomesh exhibited a higher conformability compared to that of the copper film. The copper nanomesh showed a high hydrophobicity to block external contaminants in solution while having high gas permeability and maintaining the skin humidity in a safe range. Additionally, the insertion of copper nanomesh did not affect the temperature change rate, which is important to maintain the sensation and comfort fit of the skin. Finally, the copper nanomesh was compared to the glove by wearing on our hands and interacting with various real-life objects. Using the proposed copper nanomesh, we successfully achieved an effective prevention of cross-infection and less-hindered thermal recognition of objects.  相似文献   
69.
Aims/IntroductionMany East Asians with type 2 diabetes are elderly and have a low body mass index (BMI), especially in ''super‐aged'' populations, such as Japan. This post‐hoc analysis assessed once‐weekly semaglutide efficacy and safety in Japanese individuals with type 2 diabetes across baseline age and BMI subgroups.Materials and MethodsData were derived from the Semaglutide Unabated Sustainability in Treatment of Type 2 Diabetes (SUSTAIN) Japan monotherapy and SUSTAIN Japan oral antidiabetes drug (OAD) combination trials comparing once‐weekly semaglutide with sitagliptin or OADs, respectively. Participants were grouped by baseline age (<65 and ≥65 years) and/or BMI (<25 and ≥25 kg/m2). Reductions from baseline in glycosylated hemoglobin and bodyweight (efficacy), and adverse events (safety) were assessed.ResultsIn this analysis, participants from the SUSTAIN Japan monotherapy trial (n = 308; n per subgroup; range, 8–73) and SUSTAIN Japan OAD combination trial (n = 601; n per subgroup; range, 20–168) were included. Reductions in glycosylated hemoglobin and bodyweight were numerically greater with semaglutide versus comparators across all age and BMI subgroups. Reductions from baseline in glycosylated hemoglobin ranged from –1.7 to –2.1 with semaglutide 0.5 mg, –1.8 to –2.4 with semaglutide 1.0 mg and –0.6 to –1.0 with comparators. Corresponding ranges for bodyweight (kg) were –1.0 to –2.5, –2.4 to –4.3 and 1.0 to –1.0 kg, respectively. The safety profile of semaglutide was broadly similar across BMI and age subgroups.ConclusionsIn this post‐hoc analysis with modest subgroup numbers, once‐weekly semaglutide appeared consistently more efficacious versus comparators across age and BMI subgroups in Japanese patients, with a similar safety profile.  相似文献   
70.
Trousseau syndrome-related cerebral infarction rarely occurs during chemotherapy in patients with gastrointestinal (GI) cancer, and its clinical features remain unclear. The present study aimed to examine the clinical features of Trousseau syndrome-related cerebral infarction developed during chemotherapy for GI cancer. The present retrospective cohort study consecutively enrolled 878 patients with unresectable GI cancer who received chemotherapy at the Multidisciplinary Treatment Cancer Center, Kurume University Hospital (Kurume, Japan) between April 2014 and March 2020. Patients with colorectal cancer (n=308) were the most common, followed by those with pancreatic (n=242), gastric (n=222) and biliary tract (n=59) cancer, neuroendocrine tumors (n=34) and duodenal cancer (n=11). Among the 878 patients, Trousseau syndrome-related cerebral infarction occurred in 8 (0.9%) patients with a median age of 70.5 years (range, 58–75 years), and 50% of the patients were male (4/8). In total, 3 patients had gastric cancer, 3 had pancreatic cancer and 2 had biliary tract cancer. A greater percentage of patients with Trousseau syndrome-related cerebral infarction had hyperlipidemia (38.0%) than those without (8.2%; P=0.005). Hyperlipidemia was a risk factor for occurrence of Trousseau syndrome-related cerebral infarction with an odds ratio of 7.009 (95% confidence interval, 1.785-27.513). Trousseau syndrome-related cerebral infarction developed during GI chemotherapy was rare and hyperlipidemia may predict its onset.  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