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   4708篇
  免费   202篇
  国内免费   20篇
耳鼻咽喉   172篇
儿科学   218篇
妇产科学   208篇
基础医学   670篇
口腔科学   43篇
临床医学   286篇
内科学   1115篇
皮肤病学   63篇
神经病学   435篇
特种医学   95篇
外科学   286篇
综合类   34篇
一般理论   1篇
预防医学   395篇
眼科学   86篇
药学   564篇
中国医学   12篇
肿瘤学   247篇
  2024年   6篇
  2023年   39篇
  2022年   245篇
  2021年   364篇
  2020年   128篇
  2019年   142篇
  2018年   178篇
  2017年   140篇
  2016年   143篇
  2015年   181篇
  2014年   206篇
  2013年   257篇
  2012年   402篇
  2011年   436篇
  2010年   195篇
  2009年   131篇
  2008年   259篇
  2007年   293篇
  2006年   265篇
  2005年   261篇
  2004年   249篇
  2003年   211篇
  2002年   136篇
  2001年   4篇
  2000年   4篇
  1999年   6篇
  1998年   7篇
  1997年   8篇
  1996年   8篇
  1995年   7篇
  1994年   3篇
  1993年   1篇
  1991年   2篇
  1989年   1篇
  1988年   1篇
  1985年   2篇
  1984年   2篇
  1982年   1篇
  1981年   3篇
  1980年   1篇
  1978年   2篇
排序方式: 共有4930条查询结果,搜索用时 15 毫秒
41.
AIM: To define the magnetic resonance imaging (MRI) parameters differentiating urethral hypermobility (UH) and intrinsic sphincter deficiency (ISD) in women with stress urinary incontinence (SUI).METHODS: The static and dynamic MR images of 21 patients with SUI were correlated to urodynamic (UD) findings and compared to those of 10 continent controls. For the assessment of the urethra and integrity of the urethral support structures, we applied the high-resolution endocavitary MRI, such as intraurethral MRI, endovaginal or endorectal MRI. For the functional imaging of the urethral support, we performed dynamic MRI with the pelvic phased array coil. We assessed the following MRI parameters in both the patient and the volunteer groups: (1) urethral angle; (2) bladder neck descent; (3) status of the periurethral ligaments, (4) vaginal shape; (5) urethral sphincter integrity, length and muscle thickness at mid urethra; (6) bladder neck funneling; (7) status of the puborectalis muscle; (8) pubo-vaginal distance. UDs parameters were assessed in the patient study group as follows: (1) urethral mobility angle on Q-tip test; (2) Valsalva leak point pressure (VLPP) measured at 250 cc bladder volume; and (3) maximum urethral closure pressure (MUCP). The UH type of SUI was defined with the Q-tip test angle over 30 degrees, and VLPP pressure over 60 cm H2O. The ISD incontinence was defined with MUCP pressure below 20 cm H2O, and VLPP pressure less or equal to 60 cm H2O. We considered the associations between the MRI and clinical data and UDs using a variety of statistical tools to include linear regression, multivariate logistic regression and receiver operating characteristic (ROC) analysis. All statistical analyses were performed using STATA version 9.0 (StataCorp LP, College Station, TX).RESULTS: In the incontinent group, 52% have history of vaginal delivery trauma as compared to none in control group (P < 0.001). There was no difference between the continent volunteers and incontinent patients in body habitus as assessed by the body mass index. Pubovaginal distance and periurethral ligament disruption are significantly associated with incontinence; periurethral ligament symmetricity reduces the odds of incontinence by 87%. Bladder neck funneling and length of the suprapubic urethral sphincter are significantly associated with the type of incontinence on UDs; funneling reduced the odds of pure UH by almost 95%; increasing suprapubic urethral sphincter length at rest is highly associated with UH. Both MRI variables result in a predictive model for UDs diagnosis (area under the ROC = 0.944).CONCLUSION: MRI may play an important role in assessing the contribution of hypermobility and sphincteric dysfunction to the SUI in women when considering treatment options.  相似文献   
42.
When polypropylene meshes are used in reconstructive urogynecological surgery, the erosion rates vary from 3.3% to 14% and causative factors for such erosions are still unknown in many cases. Therefore, the aim of our study was to establish the role of immunologic factors in the process of polypropylene tapes erosions after suburethral sling procedures. Serum concentrations of tumor necrosis factor α, interleukin (IL)-2, IL-4, IL-5, IL-10, and interferon (IFN)-γ were estimated in 123 patients suffering from stress urinary incontinence preoperatively and during 12 months follow-up using Human Th1/Th2 Cytokine Cytometric Bead Array I kit. The same immunological assessment was performed in each case of detected tape erosion. Statistical calculation was performed using UNIVARIATE, CORR, and NPAR1WAY procedures from Statistical Analysis System. The unpaired Student’s t test, nonparametric Mann–Whitney U test, and Wilcoxon tests were used. Preoperative IFN-γ concentration was significantly higher in women with subsequent polypropylene mesh erosion when compared to women with successful outcome (p < 0.05). Th1 cytokine profile may be related to the risk of the vaginal erosions following placement of polypropylene meshes. The way to lower erosion rate may involve exclusion of the patients immunologically prone to synthetic material erosion. The factor which can help to select such patients could be preoperative level of IFN-γ.  相似文献   
43.
Abstract   The appearance of re-stenosis after repair of an interrupted aortic arch may be a surgical challenge due to adhesions. Here, we describe an approach using off-pump coronary artery bypass grafting techniques to reach the descending aorta through a median sternotomy in a patient with aortic arch stenosis after conduit repair. The 17-year-old patient with diagnoses of interrupted aortic arch and ventricular septal defect presented after two previous operations (one left lateral thoracotomy and one median sternotomy) with a stenosed vascular graft between ascending and descending aorta. Surgery was done via re-sternotomy without cardio-pulmonary bypass. An extraanatomic graft was used to connect ascending and descending aorta. When performing the distal anastomosis, the heart was exposed using a standard suction device. This case demonstrates that the use of modern techniques may facilitate surgical approaches dramatically. In our opinion the above-described technique is the first choice for all patients requiring arch repair following multiple previous operations, performed via sternotomy and thoracotomy.  相似文献   
44.
Diabetes mellitus is considered to be a very serious lifestyle disease leading to cardiovascular complications and impaired wound healing observed in the diabetic foot syndrome. Chronic hyperglycemia is the source of the endothelial activation. The inflammatory process in diabetes is associated with the secretion of inflammatory cytokines by endothelial cells, e.g., tumor necrosis factor-alpha (TNF-α) and interleukin 6 (IL-6). The method of phototherapy using laser beam of low power (LLLT—low-level laser therapy) effectively supports the conventional treatment of diabetic vascular complications such as diabetic foot syndrome. The aim of our study was to evaluate the effect of low-power laser irradiation at two wavelengths (635 and 830 nm) on the secretion of inflammatory factors (TNF-α and IL-6) by the endothelial cell culture—HUVEC line (human umbilical vein endothelial cell)—under conditions of hyperglycemia. It is considered that adverse effects of hyperglycemia on vascular endothelial cells may be corrected by the action of LLLT, especially with the wavelength of 830 nm. It leads to the reduction of TNF-α concentration in the supernatant and enhancement of cell proliferation. Endothelial cells play an important role in the pathogenesis of diabetes; however, a small number of studies evaluate an impact of LLLT on these cells under conditions of hyperglycemia. Further work on this subject is warranted.  相似文献   
45.
BACKGROUND: A number of genetic polymorphisms have been shown to be associated with the outcome after allogeneic hematopoietic stem-cell transplantation (HSCT). In the present study, HSP70-hom polymorphism (+2763 G/A) was analyzed in the patients and donors of allogeneic HSCT in relation to transplantation outcome, susceptibility for generation of severe toxic lesions, and acute (a) graft-versus-host disease (GVHD). METHODS: One hundred thirty-three recipients of allogeneic hematopoietic stem cells and 64 haploidentical and matched unrelated donors were investigated. All these individuals were typed for dimorphism within the HSP70-hom gene (+2763 G/A) with the use of amplification refractory mutation system technique. RESULTS.: Patients with the HSP-AA homozygous genotype presented more frequently with grade II to IV toxic lesions (12 of 14 vs. 61 of 105, P = 0.039) and aGVHD (12 of 16 vs. 56 of 114, P = 0.045). Conversely, DRB1*11 was associated with a lower risk of aGVHD manifestation (10 of 31 vs. 58 of 99, P = 0.009). These contrary associations of HSP-AA and DRB1*11 with the risk of aGVHD were confirmed using logistic regression modeling in multivariable analysis (HSP-AA, odds ratio [OR] = 3.833, P = 0.004; DRB1*11, OR = 0.224, P = 0.048). None of donor HSP genotypes or patient-donor incompatibility within HSP alleles was associated with susceptibility to toxic complications or aGVHD. CONCLUSIONS: Polymorphism of the HSP70-hom gene is associated with the development of posttransplant complications. Recipient HSP-AA homozygous genotype is a risk factor for aGVHD.  相似文献   
46.
Results of the research on the lowering of allergenicity of wheat flour fermented using homo- and heterofermentative lactic acid bacteria and mixed cultures with yeast were discussed. The gliadins’ immunoreactivity was measured using the indirect non-competitive enzyme-linked immunosorbent assay method. The biggest decrease of the immunoreactivity of gliadin fraction was observed in the case of fermentation performed with the use of mixed cultures of lactic acid bacteria and yeast. This way of wheat flour modification seems to be promising, because fermentation is a natural process causing not only lowering of the allergenicity, but also improving organoleptic and nutritional values of obtained products.  相似文献   
47.
48.
Among dipterans of medical and veterinary importance, the mosquitoes (Culicidae) play the most important role both as vectors and nuisance insects. Mass occurrence of floodwater mosquito species in the flooded area in Wroc?aw district (Lower Silesia, Poland) in 1997 has enhanced the already existed problem of mosquito control. A successful model of control strategy for the city based on the currently recommended integrated methodologies with special emphasis on preventive treatment of aquatic larvae with microbial insecticides has been conducted. Bacillus thuringiensis israelensis-based formulations replaced chemicals to control Culex pipiens and Culiseta annulata--two dominant species out of eight noticed during field study in Wroc?aw area in the years 1998-2000. Use of Bti larvicide or other biocontrol agent, conserving biodiversity, requires collecting entomological data, mapping and treating all breeding sources as well as the designing appropriate strategies every year.  相似文献   
49.
50.
GeroScience - A complex picture of factors influencing cognition is necessary to be drawn for a better understanding of the role of potentially modifiable factors in dementia. The aim was to assess...  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