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   6255篇
  免费   360篇
  国内免费   33篇
耳鼻咽喉   69篇
儿科学   151篇
妇产科学   123篇
基础医学   1047篇
口腔科学   48篇
临床医学   589篇
内科学   1398篇
皮肤病学   84篇
神经病学   719篇
特种医学   341篇
外科学   875篇
综合类   27篇
一般理论   6篇
预防医学   281篇
眼科学   86篇
药学   420篇
中国医学   6篇
肿瘤学   378篇
  2023年   37篇
  2022年   89篇
  2021年   173篇
  2020年   87篇
  2019年   135篇
  2018年   187篇
  2017年   132篇
  2016年   137篇
  2015年   191篇
  2014年   233篇
  2013年   352篇
  2012年   483篇
  2011年   504篇
  2010年   282篇
  2009年   285篇
  2008年   414篇
  2007年   428篇
  2006年   409篇
  2005年   410篇
  2004年   373篇
  2003年   292篇
  2002年   310篇
  2001年   55篇
  2000年   25篇
  1999年   44篇
  1998年   46篇
  1997年   47篇
  1996年   39篇
  1995年   47篇
  1994年   24篇
  1993年   23篇
  1992年   22篇
  1991年   9篇
  1990年   11篇
  1989年   21篇
  1988年   11篇
  1985年   13篇
  1984年   12篇
  1983年   15篇
  1982年   25篇
  1981年   23篇
  1980年   12篇
  1979年   16篇
  1978年   17篇
  1977年   9篇
  1976年   9篇
  1974年   9篇
  1972年   14篇
  1971年   6篇
  1968年   7篇
排序方式: 共有6648条查询结果,搜索用时 5 毫秒
41.
BackgroundTo evaluate whether stone extraction with a loop ureteral catheter (LUC) in distal ureteral stones is associated with a higher frequency of ureteral strictures compared to treatment with primary ureteroscopic stone removal (p-URS) or ureteroscopic laser lithotripsy (l-URS).MethodsFive hundred and forty-seven consecutive patients were primarily endourologically treated for distal ureteral stones in our department between 2005 and 2019 and included in the study protocol. Data was retrospectively obtained from the patients’ charts and medical reports as well as from office-based urologists. Data analysis was performed using Fisher’s exact test, Mann-Whitney test or Student’s t-test as appropriate. A level of P<0.05 was assigned statistical significance.ResultsFour hundred and twelve patients were treated by URS (p-URS n=304, l-URS n=108) and another 135 by LUC stone extraction. Median follow-up was 41 [2–159] months. There was no difference between the groups concerning age, gender, proportion of patients with ureteral stenting, operating time, hospitalization or readmission rates. The number of ureteric strictures was small in all procedures [n=3 (1.0%) in p-URS, n=2 (1.9%) in l-URS and n=2 (1.5%) in LUC] and there was no difference between the groups concerning this serious complication (p-URS vs. LUC: P=0.6465; l-URS vs. LUC: P=0.9999).ConclusionsIn small distal stones, LUC stone extraction still is an alternative to URS procedures in stone management with comparable results concerning postinterventional ureteral strictures. In experienced hands, it still has its value in accurately selected patients.  相似文献   
42.
Liver resection still represent the treatment of choice for liver malignancies, but in some cases inadequate future remnant liver (FRL) can lead to post hepatectomy liver failure (PHLF) that still represents the most common cause of death after hepatectomy. Several strategies in recent era have been developed in order to generate a compensatory hypertrophy of the FRL, reducing the risk of post hepatectomy liver failure. Portal vein embolization, portal vein ligation, and ALLPS are the most popular techniques historically adopted up to now. The liver venous deprivation and the radio-embolization are the most recent promising techniques. Despite even more precise tools to calculate the relationship among volume and function, such as scintigraphy with 99mTc-mebrofenin (HBS), no consensus is still available to define which of the above mentioned augmentation strategy is more adequate in terms of kind of surgery, complexity of the pathology and quality of liver parenchyma. The aim of this article is to analyse these different strategies to achieve sufficient FRL.  相似文献   
43.
ObjectiveTo validate a Russian-language version of the World Health Organization’s Alcohol Use Disorders Identification Test (AUDIT).MethodsWe invited 2173 patients from 21 rural and urban primary health-care centres in nine Russian regions to participate in the study (143 declined and eight were excluded). In a standardized interview, patients who had consumed alcohol in the past 12 months provided information on their sociodemographic characteristics and completed the Russian AUDIT, the Kessler Psychological Distress Scale and the Composite International Diagnostic Interview to identify problem drinking and alcohol use disorders. We assessed the feasibility of administering the test, its internal consistency and its ability to predict hazardous drinking and alcohol use disorders in primary health care in the Russian Federation.FindingsOf the 2022 patients included in the study, 1497 were current drinkers with Russian AUDIT scores. The test was internally consistent with good psychometric properties (Cronbach’s α : 0.842) and accurately predicted alcohol use disorders and other outcomes (area under the curve > 75%). A three-item short form of the test correlated well with the full instrument and had similar predictive power (area under the curve > 80%). We determined sex-specific thresholds for all outcomes, as non-specific thresholds resulted in few women being identified.ConclusionWith the validated Russian AUDIT, there is no longer a barrier to introducing screening and brief interventions into primary health care in the Russian Federation to supplement successful alcohol control policies.  相似文献   
44.
The two-pore-domain potassium channels TASK-1, TASK-3 and TASK-5 possess a conserved C-terminal motif of five amino acids. Truncation of the C-terminus of TASK-1 strongly reduced the currents measured after heterologous expression in Xenopus oocytes or HEK293 cells and decreased surface membrane expression of GFP-tagged channel proteins. Two-hybrid analysis showed that the C-terminal domain of TASK-1, TASK-3 and TASK-5, but not TASK-4, interacts with isoforms of the adapter protein 14-3-3. A pentapeptide motif at the extreme C-terminus of TASK-1, RRx(S/T)x, was found to be sufficient for weak but significant interaction with 14-3-3, whereas the last 40 amino acids of TASK-1 were required for strong binding. Deletion of a single amino acid at the C-terminal end of TASK-1 or TASK-3 abolished binding of 14-3-3 and strongly reduced the macroscopic currents observed in Xenopus oocytes. TASK-1 mutants that failed to interact with 14-3-3 isoforms (V411*, S410A, S410D) also produced only very weak macroscopic currents. In contrast, the mutant TASK-1 S409A, which interacts with 14-3-3-like wild-type channels, displayed normal macroscopic currents. Co-injection of 14-3-3ζ cRNA increased TASK-1 current in Xenopus oocytes by about 70 %. After co-transfection in HEK293 cells, TASK-1 and 14-3-3ζ (but not TASK-1ΔC5 and 14-3-3ζ) could be co-immunoprecipitated. Furthermore, TASK-1 and 14-3-3 could be co-immunoprecipitated in synaptic membrane extracts and postsynaptic density membranes. Our findings suggest that interaction of 14-3-3 with TASK-1 or TASK-3 may promote the trafficking of the channels to the surface membrane.  相似文献   
45.
Interferons (IFNs) exert antitumor effects in several human malignancies, but their mechanism of action is unclear. There is a great variability in sensitivity to IFN treatment depending on both tumor type and the individual patient. The reason for this variable sensitivity is not known. The fact that several IFN-induced anticellular effects are exerted through modulation of proto-oncogenes and tumor suppressor genes may indicate that the malignant genotype may be decisive in the cell's sensitivity to IFN. To determine if a deregulated oncogene could alter the cellular response to IFN, a mouse lymphoma cell line (J3D) was stably transfected with the viral human papillomavirus-16 (HPV-16) E7 oncogene. The E7-transfected cells and their respective mock-transfected sister clones were treated with IFN-alpha and examined for possible IFN-induced anticellular effects. We found that the E7-transfected clones were greatly sensitized to IFN-alpha-induced apoptosis compared with their mock-transfected counterparts. Induction of apoptosis in the transfected cells correlated with the ability of IFN to activate parts of the proapoptotic machinery specifically in these cells, including activation of caspases and the proapoptotic protein Bak. In summary, our data suggest that transfection of malignant cells with the E7 oncogene can sensitize them to IFN-alpha-induced apoptosis. This demonstrates that an oncogenic event may alter the cellular sensitivity to IFN and might also have implications for treatment of HPV-related diseases with IFN.  相似文献   
46.
Purpose. The described structure pharmacokinetic pharmacodynamic relationships (SPPR) study explored the utilization of tetramethylcyclopropane analogues of valpromide (VPD), or tetra-methylcyclopropane carboxamide derivatives of valproic acid (VPA) as new antiepileptics. Methods. The study was carried out by investigating the pharmacokinetics in dogs and pharmacodynamics (anticonvulsant activity and neurotoxicity) of the following three cyclopropane analogues of VPD: 2,2,3,3-tetramethylcyclopropane carboxamide (TMCD), N-methyl TMCD (M-TMCD) and N-[(2,2,3,3-tetramethylcyclopropyl)carbonyl]-glycinamide (TMC-GLD). Results. The three investigated compounds showed a good anticonvulsant profile in mice and rats due to the fact that they were metabolically stable VPD analogues which were not biotransformed to their non-active acid, 2,2,3,3-tetramethylcyclopropane carboxylic acid (TMCA). M-TMCD was metabolized to TMCD and TMC-GLD underwent partial biotransformation to its glycine analogue N-[(2,2,3,3-tetramethylcyclopropyl)carbonyl]-glycine (TMC-GLN). Unlike TMC-GLN, the above mentioned amides had low clearance and a relatively long half life. Conclusions. In contrast to VPD which is biotransformed to VPA, the aforementioned cyclopropane derivatives were found to be stable to amide-acid biotransformation. TMCD and M-TMCD show that cyclic analogues of VPD, like its aliphatic isomers, must have either two substitutions at the position to the carbonyl, such as in the case of TMCD, or a substitution in the and in the positions like in the VPD isomer, valnoctamide (VCD). This paper discusses the antiepileptic potential of tetramethylcyclopropane analogues of VPD which are in animal models more potent than VPA and may be non-teratogenic and non-hepatotoxic.  相似文献   
47.
48.
Objectives: To describe an approach based on initial tissue-conserving surgery used to obtain histologically determined prognostic information that has therapeutic implications and the potential to enhance preservation of function. Study Design: Analysis of a group of patients with head and neck cancer treated initially with tissue-conserving surgery based on Mohs' histographic sectioning and selected neck dissection to derive histologically determined prognostic information with therapeutic implications and preservation in function. Methods: This study is primarily based on an analysis of patients from January 1, 1989, through June 4, 1996 assigned to a protocol evaluating resection of oral cavity squamous cell cancer with margin control using Mohs' histographic technique and/or a group of patients with neck assessment of N0 on clinical examination who are undergoing supraomohyoid neck dissections. Results: Thirty-three primary tumor resections were performed using the Mohs' technique, and 54% required two or more Mohs' sections before clear histologic margins were obtained following resection based on clinically determined negative margins. There were 44 patients who underwent unilateral or bilateral supraomohyoid neck dissections, and 33% had occult, histologically positive nodes. When compared with the disease of the neck specimens, a preoperative computed tomography scan had a sensitivity of 25%, a specificity of 77%, and an accuracy of 63%. Conclusions: This report describes the effectiveness of Mohs' histographic sectioning and selective neck dissection as a means of determining prognostic information that can be used to develop a focused and cost-effective treatment program that, along with contemporary reconstructive techniques, provides a potential enhancement of function preservation. Laryngoscope, 108:1599–1604, 1998  相似文献   
49.
50.
Despite recent progress in the identification and characterization of numerous nasal biotransformation enzymes in laboratory animals, the expression of biotransformation genes in human nasal mucosa remains difficult to study. Given the potential role of nasal biotransformation enzymes in the metabolism of airborne chemicals, including fragrance compounds and therapeutic agents, as well as the potential interspecies differences between laboratory animals and humans, it would be highly desirable to identify those biotransformation genes that are expressed in human nasal mucosa. In this study, a global gene expression analysis was performed to compare biotransformation enzymes expressed in human fetal and adult nasal mucosa to those expressed in liver. The identities of a list of biotransformation genes with apparently nasal mucosa-selective expression were subsequently confirmed by RNA-polymerase chain reaction (PCR) and DNA sequencing of the PCR products. Further quantitative RNA-PCR experiments indicated that, in the fetus, aldehyde dehydrogenase 6 (ALDH6), CYP1B1, CYP2F1, CYP4B1, and UDP glucuronosyltransferase 2A1 are expressed preferentially in the nasal mucosa and that ALDH7, flavin-containing monooxygenase 1, and glutathione S-transferase P1 are at least as abundant in the nasal mucosa as in the liver. The nasal mucosal expression of CYP2E1 was also detected. These findings provide a basis for further explorations of the metabolic capacity of the human nasal mucosa for xenobiotic compounds.  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