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   5074篇
  免费   314篇
  国内免费   18篇
耳鼻咽喉   42篇
儿科学   119篇
妇产科学   84篇
基础医学   944篇
口腔科学   93篇
临床医学   516篇
内科学   1054篇
皮肤病学   184篇
神经病学   575篇
特种医学   220篇
外科学   422篇
综合类   35篇
一般理论   3篇
预防医学   336篇
眼科学   62篇
药学   347篇
中国医学   8篇
肿瘤学   362篇
  2023年   26篇
  2022年   53篇
  2021年   118篇
  2020年   70篇
  2019年   83篇
  2018年   91篇
  2017年   79篇
  2016年   98篇
  2015年   175篇
  2014年   184篇
  2013年   210篇
  2012年   370篇
  2011年   421篇
  2010年   234篇
  2009年   212篇
  2008年   386篇
  2007年   417篇
  2006年   336篇
  2005年   375篇
  2004年   315篇
  2003年   318篇
  2002年   280篇
  2001年   37篇
  2000年   20篇
  1999年   44篇
  1998年   71篇
  1997年   57篇
  1996年   42篇
  1995年   41篇
  1994年   34篇
  1993年   24篇
  1992年   17篇
  1991年   17篇
  1990年   13篇
  1989年   7篇
  1988年   11篇
  1987年   10篇
  1986年   11篇
  1985年   11篇
  1984年   12篇
  1983年   10篇
  1982年   7篇
  1981年   10篇
  1980年   9篇
  1979年   6篇
  1978年   4篇
  1977年   4篇
  1975年   5篇
  1973年   3篇
  1972年   3篇
排序方式: 共有5406条查询结果,搜索用时 15 毫秒
61.
BACKGROUND: It has been shown that the macula densa participates in the regulation of increased renin expression in two-kidney one-clip (2K1C) renovascular hypertension. Prostaglandins might be one of the mediators of macula densa function, because the cyclooxygenase-2 (COX-2), one of the rate-limiting enzymes of the prostaglandin pathway, is upregulated in 2K1C renovascular hypertensive rats. We tested the effect of chronic COX-2 inhibition on blood pressure, urinary aldosterone excretion and kidney morphology, as well as kidney function. METHODS: Four groups were established: two groups of 2K1C renovascular hypertensive rats treated with the specific COX-2 inhibitor Celecoxib (cele) (15 mg/kg per day) or placebo immediately after operation, and two sham-operated control groups fed with Celecoxib or placebo. RESULTS: Long-term COX-2 inhibition in 2K1C renovascular hypertensive rats did not alter blood pressure at any point of time. Urinary aldosterone excretion was elevated by clipping the renal artery (2K1C, 8.1 +/- 1.9, versus controls, 3.6 +/- 0.5 ng/24 h; P = 0.05) but was not influenced by treatment with Celecoxib. Also, Celecoxib treatment did not alter glomerular filtration rate (GFR), serum sodium, serum creatinine, serum urea or proteinuria in 2K1C renovascular hypertensive rats. Interstitial fibrosis of the left clipped kidney was markedly reduced (2K1C, 6.19 +/- 0.83% versus 2K1C + cele 3.00 +/- 0.68% of total area; P = 0.012), whereas the interstitial fibrosis of the non-clipped kidney or the glomerulosclerosis of both kidneys were not affected by Celecoxib treatment. CONCLUSIONS: Celecoxib reduces the interstitial fibrosis of the clipped kidney. Blood pressure, urinary aldosterone excretion or whole kidney function were not affected in renal hypertensive rats.  相似文献   
62.
The aquatic ecosystem is the natural habitat of microorganisms including Vibrio and Aeromonas genus which are pathogenic to human and animals. In the present investigation the frequency of these bacteria and the enzymatic characteristics of 34 Vibrio alginolyticus strains isolated from bivalves harvested in Venice Lagoon (Italy) and Guanabara Bay (Brazil) were carried out from November 2003 to February 2004. The mussels' samples were submitted to enrichment in Alkaline Peptone Water (APW) added with 1% of sodium chloride (NaCl) and APW plus 3% NaCl incubated at 37 degrees C for 18-24 h. Following the samples were streaked onto TCBS Agar (Thiossulfate Citrate Bile Sucrose Agar) and the suspected colonies were submitted to biochemical characterization. Also, the Vibrio alginolyticus strains were evaluated to collagenase, elastase and chondroitinase production. The results showed the isolation of 127 microorganisms distributed as follows: 105 Vibrio strains such as V. alginolyticus (32.4%), V. harveyi (19%) and V. parahaemolyticus (7.6%), 20 Aeromonas strains and two Plesiomonas shigelloides were the main pathogens isolated. We observed the production of the three enzymes from V. alginolyticus strains considered as the main virulence factors of the bacteria, especially in cases of human dermatological infection.  相似文献   
63.
OBJECTIVE: Evidence is accumulating that recurrent abdominal pain (RAP) in children is associated with visceral hyperalgesia. However, it is not known whether somatic sensitivity is altered as well. Therefore, the aim of our study was to assess somatic pain sensitivity in children with RAP and healthy controls at the abdomen and a distal site (thenar).
METHODS: We examined 20 children with RAP (age 8–14) and 23 healthy control children (age 9–14). Heat and mechanical pain thresholds as well as measures of perceptual sensitization in response to repetitive mechanical or tonic thermal noxious stimulation were assessed.
RESULTS: At the abdominal site, pain sensitivity in children with RAP did not differ significantly when compared to controls. At the thenar, pain thresholds of children in the RAP group were not significantly different from control children. However, children with RAP showed less perceptual sensitization in response to tonic heat and repetitive mechanical stimuli (ps ≤ 0.05) than controls.
CONCLUSIONS: We found no evidence for somatic hyperalgesia in RAP arguing against generalized hyperalgesia in these children. Somatic hypoalgesia at the thenar might either be related to a dysregulation of sensory processing and/or attentional avoidance of pain-related stimuli.  相似文献   
64.
65.
Dermatofibrosarcoma protuberans (DFSP) is a dermal and subcutaneous tumor of intermediate malignancy. The most remarkable cytogenetic feature of DFSP is the chromosomal translocation t(17;22)(q22;q13), causing a fusion of the platelet-derived growth factor beta chain (PDGFB) gene at 22q13, and the collagen type 1 alpha 1 (COL1A1) at 17q22. The aim of the study was to analyze the molecular characteristic of DFSP in conjunction with histopathological and clinical features.  相似文献   
66.
European Journal of Clinical Microbiology & Infectious Diseases - Complicated urinary tract infection (cUTI) is a frequent cause of morbidity. In this multinational retrospective cohort study,...  相似文献   
67.
Background

SARS-CoV-2 infection leads to high viral loads in the upper respiratory tract that may be determinant in virus dissemination. The extent of intranasal antiviral response in relation to symptoms is unknown. Understanding how local innate responses control virus is key in the development of therapeutic approaches.

Methods

SARS-CoV-2-infected patients were enrolled in an observational study conducted at the Geneva University Hospitals, Switzerland, investigating virological and immunological characteristics. Nasal wash and serum specimens from a subset of patients were collected to measure viral load, IgA specific for the S1 domain of the spike protein, and a cytokine panel at different time points after infection; cytokine levels were analyzed in relation to symptoms.

Results

Samples from 13 SARS-CoV-2-infected patients and six controls were analyzed. We found an increase in CXCL10 and IL-6, whose levels remained elevated for up to 3 weeks after symptom onset. SARS-CoV-2 infection also induced CCL2 and GM-CSF, suggesting local recruitment and activation of myeloid cells. Local cytokine levels correlated with viral load but not with serum cytokine levels, nor with specific symptoms, including anosmia. Some patients had S1-specific IgA in the nasal cavity while almost none had IgG.

Conclusion

The nasal epithelium is an active site of cytokine response against SARS-CoV-2 that can last more than 2 weeks; in this mild COVID-19 cohort, anosmia was not associated with increases in any locally produced cytokines.

  相似文献   
68.
69.
Procedural accidents are eventualities that may occur during endodontic treatment because of lack of attention to detail or even unforeseeable situations. Knowledge of the root canal anatomy and its variations is a prerequisite for successful endodontic treatment. This case report describes an endodontic treatment where there was an intercurrence, generating deviation and perforation, which was solved with the aid of guided endodontics. A 37 years old, ASA1, was referred to the clinic for localisation and treatment of a calcified canal of the second right upper premolar. The tomographic images revealed the presence of only one canal and deviation with apical perforation. With the help of CBCT and CAD/CAM, it was possible to perform the guided access technique even after deviation and root perforation. Once again, this technique proved to be safe and predictable, allowing for a favourable prognosis in the long term.  相似文献   
70.
ObjectiveTo compare the performance, reliability, and validity of functional tests between women with and without patellofemoral pain.MethodsTwenty women with a diagnosis of patellofemoral pain between 18 and 40 years of age and 20 age-matched pain-free controls participated in the study. All participants performed a set of five function tests: sitting-rising test, sit-to-stand in 30 seconds, stair-climb test, stair descent test, and six-minute step test. To investigate reliability, participants were assessed on two different days, seven days apart, by two independent investigators blinded to the results of the other investigator. Validity was evaluated through associations with the results on the Anterior Knee Pain Scale.ResultsPerformance in the tests was worse in women with patellofemoral pain than in the control group for the sit-to-stand in 30 seconds (mean difference [MD] 3.4reps; 95%CI: 0.4, 6.4), stair-climb test (MD: 0.36 s; 95%CI: 0.1, 0.63), and six-minute step test (MD: 45reps; 95%CI: 20, 70). No differences were observed for the sitting-rising and stair descent tests. All tests in both groups showed moderate to excellent intra- and inter-rater reliability (intraclass correlation coefficients: 0.61 to 0.91 and 0.72 to 0.96, respectively). Finally, only the results on the sit-to-stand in 30 seconds test correlated with the Anterior Knee Pain Scale (r = 0.44, p = 0.047) in the patellofemoral pain group.ConclusionWomen with patellofemoral pain present lower performance on some functional tests. Functional tests are reliable in patients with patellofemoral pain, although they are not associated with the results on the Anterior Knee Pain Scale self-questionnaire.  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