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   1913篇
  免费   100篇
  国内免费   3篇
耳鼻咽喉   23篇
儿科学   79篇
妇产科学   58篇
基础医学   263篇
口腔科学   48篇
临床医学   218篇
内科学   282篇
皮肤病学   52篇
神经病学   250篇
特种医学   31篇
外科学   162篇
综合类   4篇
预防医学   214篇
眼科学   11篇
药学   200篇
中国医学   3篇
肿瘤学   118篇
  2024年   5篇
  2023年   14篇
  2022年   22篇
  2021年   50篇
  2020年   44篇
  2019年   41篇
  2018年   59篇
  2017年   44篇
  2016年   51篇
  2015年   48篇
  2014年   73篇
  2013年   116篇
  2012年   137篇
  2011年   163篇
  2010年   93篇
  2009年   92篇
  2008年   134篇
  2007年   150篇
  2006年   128篇
  2005年   104篇
  2004年   113篇
  2003年   105篇
  2002年   96篇
  2001年   17篇
  2000年   8篇
  1999年   9篇
  1998年   17篇
  1997年   10篇
  1996年   7篇
  1995年   9篇
  1994年   8篇
  1993年   10篇
  1992年   5篇
  1991年   5篇
  1990年   3篇
  1989年   4篇
  1988年   1篇
  1987年   1篇
  1986年   4篇
  1985年   3篇
  1984年   4篇
  1983年   2篇
  1982年   2篇
  1981年   1篇
  1980年   1篇
  1979年   1篇
  1977年   1篇
  1975年   1篇
排序方式: 共有2016条查询结果,搜索用时 10 毫秒
11.
Anti-IgE-induced histamine release from human leukocytes is inhibited when the cells before challenge are cultured overnight in the presence of glucocorticoids (GCSs). The present report suggests that the GCSs might exert their effect by at least a dual mechanism of action. Histamine release was induced by a suboptimum concentration of anti-IgE. When the release recorded in the presence of the steroid is plotted against the release recorded in its absence, the data points of several experiments fit a regression line characterized by two parameters: its slope and its intercept with the abscissa. Structure-activity examination with selected GCSs indicates that the orders of potency for affecting these two parameters are not identical. Furthermore, pulse experiments suggest that the cells require different times of contact with the steroid to express inhibition according to the two parameters. The removal of adherent cells or platelets did not markedly affect the degree of leukocyte histamine release or its inhibition by a given GCS, suggesting that the steroid interacts directly with the basophil. Finally, steroid-induced inhibition was not affected by the putative phospholipase A2-inhibitor p-bromophenacylbromide (BPB) or the 5-lipoxygenase inhibitor nordihydroguaiaretic acid (NDGA).  相似文献   
12.

Background  

Familial Hypercholesterolemia (FH) is a common genetic disease and at the molecular level most often due to mutations in the LDL receptor gene. In genetically heterogeneous populations, major structural rearrangements account for about 5% of patients with LDL receptor gene mutations.  相似文献   
13.
The expression of CD59 and other complement regulators was studied in human cerebellum from 14 individuals with no cerebellar pathology, from one patient with multiple sclerosis (MS) and from two patients with paraneoplastic cerebellar degeneration (PCD). CD59 was present on the Purkinje cells at various levels in eight of the 14 cases with no cerebellar pathology. CD59 was also present on the Purkinje cells of the patient with MS, but not on the scarce remaining Purkinje cells of the two patients with PCD. Other complement regulators (CD35, CD46 and CD55) were not expressed on the Purkinje cells, whereas CD59, CD46 and CD55 were present on the molecular, granulosa and endothelial cells. The results suggest that Purkinje cells not expressing CD59 could be especially prone to complement-mediated damage.  相似文献   
14.
Our previous studies have indicated that the IgG-binding M-family proteins (IgGBP) of group A streptococci may be involved in eliciting experimental acute poststreptococcal glomerulonephritis (APSGN) in the rabbit. These surface proteins were also found to trigger production of anti-IgG, which might conceivably act to enhance renal deposition of immune complexes (IC). In the present study, a clinical isolate of serotype M22 (strain AL168), an isogenic double mutant deficient for both the IgGBPs Mrp and Emm, as well as mutants deficient in only one of the proteins were tested for capacity to induce glomerulonephritis. Streptococci to be used for injecting rabbits were heat-killed. Surface-bound IgG was removed by 1 M KSCN and cells were then repeatedly washed in PBS before use. Rabbits were injected intravenously with 109 cells three times a week for 8 weeks and, following one month of rest, for another 6 weeks. Deposits of IgG and C3 as well as induced chemokines TNF-alpha, IL-1beta and IL-6 were traced in cryostat sections using specific antibodies and appropriate peroxidase-labelled anti-antibodies. In four rabbits immunized with the double mutant strain, no deposits were found, and as examined by TEM, only subtle and transient renal changes were observed. In contrast, the original strain AL168 induced pronounced inflammatory and degenerative glomerular changes in all four rabbits injected, and deposits of TNF-alpha, IL-1beta and IL-6 were found in mesangial and endothelial cells. Similar deposits and glomerular changes were seen in all eight rabbits injected with the mrp-emm+ mutant and in four out of seven animals receiving the mrp+emm- mutant. There was a highly significant correlation between high levels of circulating anti-IgG and development of APSGN. These results confirm an important role of streptococcal IgGBP in triggering experimental APSGN as earlier proposed by our group.  相似文献   
15.
Bundesgesundheitsblatt - Gesundheitsforschung - Gesundheitsschutz - Ein Erratum zu dieser Publikation wurde veröffentlicht: https://doi.org/10.1007/s00103-019-02901-5  相似文献   
16.
Alcohol abuse after liver transplantation can seriously impact graft and patient survival. However, to date, there is no defined standard procedure to identify patients consuming alcohol after liver transplantation. The aim of this study was to analyze the diagnostic value and clinical impact of routinely measured urinary ethyl glucuronide (uEtG) – a metabolite of ethanol – in patients after liver transplantation. Data of 362 consecutive patients after liver transplantation who visited the University Hospital of Tuebingen for outpatient follow-up were analyzed. Forty-eight patients (13%) displayed positive uEtG results. The uEtG positive group contained significantly more patients with pretransplant alcoholic liver disease. However, two thirds of the uEtG positive patients had no history of pretransplant alcoholic liver disease. Several clinical parameters were significantly associated with positive uEtG. In order to enable a more cost-effective application of uEtG in the future, a clinical risk score was developed (specificity 0.95). In conclusion, routine testing for uEtG reveals a considerable percentage of patients practicing alcohol intake after liver transplantation. Application of our proposed risk score could help focusing uEtG testing on patients at risk.  相似文献   
17.
PURPOSE: Members of a family with hereditary gastrointestinal stromal tumors (GISTs) and a germline KIT oncogene mutation were evaluated for other potential syndrome manifestations. A tumor from the proband was analyzed to compare features with sporadic GISTs. PATIENTS AND METHODS: Members of a kindred in which six relatives in four consecutive generations comprised an autosomal dominant pattern of documented GISTs and cutaneous lesions underwent physical examination, imaging studies, and germline KIT analysis. A recurrent GIST from the proband was studied using microarray, karyotypic, immunohistochemical, and immunoblotting techniques. RESULTS: In addition to evidence of multiple GISTs, lentigines, malignant melanoma, and an angioleiomyoma were identified in relatives. A previously reported gain-of-function missense mutation in KIT exon 11 (T --> C) that results in a V559A substitution within the juxtamembrane domain was identified in three family members. The proband's recurrent gastric GIST had a 44,XY-14,-22 karyotype and immunohistochemical evidence of strong diffuse cytoplasmic KIT expression without expression of actin, desmin, or S-100. Immunoblotting showed strong expression of phosphorylated KIT and downstream signaling intermediates (AKT and MAPK) at levels comparable with those reported in sporadic GISTs. cDNA array profiling demonstrated clustering with sporadic GISTs, and expression of GIST markers comparable to sporadic GISTs. CONCLUSION: These studies provide the first evidence that gene expression and mechanisms of cytogenetic progression and cell signaling are indistinguishable in familial and sporadic GISTs. Current investigations of molecularly targeted therapies in GIST patients provide opportunities to increase the understanding of features of the hereditary syndrome, and risk factors and molecular pathways of the neoplastic phenotypes.  相似文献   
18.
A population-based case-control study was conducted in two regions ofSweden and Norway to investigate the association between dietary habits andthe risk of thyroid cancer. The consumption of selected foods was reported ina self-completed food-frequency questionnaire by 246 cases withhistologically confirmed papillary (n = 209) and follicular (n = 37) thyroidcarcinoma, and 440 age- and gender-matched controls. Odds ratios (OR) andtheir 95 percent confidence interval (CI) were calculated as estimates of therelative risk using conditional logistic regression. High consumption ofbutter (OR = 1.6, CI = 1.1-2.5) and cheese (OR = 1.5, CI = 1.0-2.4) wasassociated with increased risks. Residence in areas of endemic goiter inSweden was associated with an elevated risk, especially among women (OR =2.5, CI = 1.3-4.9). High consumption of cruciferous vegetables was associatedwith increased risk only in persons who ever lived in such areas. A decreasedrisk was associated with consumption of iodized salt in northern Norway, andwith use of iodized salt during adolescence among women (OR = 0.6, CI =0.6-1.0). The results of this study suggest a role of diet and environment inthe risk of thyroid cancer.  相似文献   
19.

Objectives

Lung cancer patients and their partners are prone to high levels of depression and anxiety or severe distress related to the poor prognosis of the illness. However, there remain doubts regarding the extent to which this distress exceeds levels in the general population. This study explored levels of depression and generalized anxiety for comparison with matched data of a representative sample from the general population. Additionally, covariance of distress between the two partners, together with disease-specific components and differences were investigated.

Materials and methods

In a cross-sectional survey, 54 pairs of lung cancer patients and their partners (n = 108) were assessed for depression and anxiety, cancer-related distress, unmet needs and disclosure in communication. Comparisons between distress levels of participating couples and matched community-comparisons (n = 162) were conducted. Additionally, multilevel analysis for estimating intra-dyadic associations of anxiety and depression was computed. Components of distress, needs and aspects of communication were explored via item mean values.

Results

Lung cancer patients as well as their partners exhibited significantly higher levels of depression and anxiety when compared to community-based comparison subjects (patients: mean difference of 1.01 for depression with a relative risk (RR) of 4.5 and 0.84 for anxiety with RR = 6.1; partners: 1.17 for depression with RR = 4.6 and 1.59 for anxiety with RR = 7.6). Partial intraclass correlations between patients and partners were weak (PIC = .29 for depression; PIC = .21 for anxiety). Fear of progression emerged as main component of distress for both patients and partners, although differing stressors were described.

Conclusion

Lung cancer-affected couples exhibit levels of depression and anxiety far exceeding those of the general community. In clinical practice, patients and partners should be assessed separately for distress against the background of weak intra-dyadic associations. In cases of significant depression or anxiety, referral for psychosocial treatment is indicated and has been shown to improve quality of life.  相似文献   
20.
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