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   8699篇
  免费   593篇
  国内免费   23篇
耳鼻咽喉   42篇
儿科学   252篇
妇产科学   249篇
基础医学   1317篇
口腔科学   181篇
临床医学   1015篇
内科学   1661篇
皮肤病学   240篇
神经病学   1156篇
特种医学   217篇
外科学   703篇
综合类   67篇
一般理论   9篇
预防医学   793篇
眼科学   300篇
药学   530篇
中国医学   20篇
肿瘤学   563篇
  2023年   78篇
  2022年   118篇
  2021年   205篇
  2020年   185篇
  2019年   215篇
  2018年   271篇
  2017年   212篇
  2016年   222篇
  2015年   270篇
  2014年   300篇
  2013年   456篇
  2012年   733篇
  2011年   718篇
  2010年   374篇
  2009年   341篇
  2008年   641篇
  2007年   590篇
  2006年   548篇
  2005年   518篇
  2004年   480篇
  2003年   446篇
  2002年   434篇
  2001年   63篇
  2000年   39篇
  1999年   61篇
  1998年   83篇
  1997年   72篇
  1996年   66篇
  1995年   45篇
  1994年   50篇
  1993年   41篇
  1992年   28篇
  1991年   23篇
  1990年   17篇
  1989年   17篇
  1988年   16篇
  1987年   20篇
  1986年   20篇
  1985年   17篇
  1984年   21篇
  1983年   16篇
  1982年   23篇
  1980年   16篇
  1978年   22篇
  1977年   14篇
  1976年   12篇
  1975年   12篇
  1971年   12篇
  1970年   10篇
  1968年   10篇
排序方式: 共有9315条查询结果,搜索用时 15 毫秒
991.
RELA, RELB, CREL, NFKB1 and NFKB2, and the upstream regulators NEMO and NIK were knocked-down in lymph endothelial cells (LECs) and in MDA-MB231 breast cancer spheroids to study the contribution of NF-κB in vascular barrier breaching. Suppression of RELA, NFKB1 and NEMO inhibited “circular chemo-repellent induced defects” (CCIDs), which form when cancer cells cross the lymphatic vasculature, by ~20–30%. Suppression of RELB, NFKB2 and NIK inhibited CCIDs by only ~10–15%. In MDA-MB231 cells RELA and NFKB1 constituted MMP1 expression, which caused the activation of PAR1 in adjacent LECs. The knock-down of MMP1 in MDA-MB231 spheroids and pharmacological inhibition of PAR1 in LECs inhibited CCID formation by ~30%. Intracellular Ca2+ release in LECs, which was induced by recombinant MMP1, was suppressed by the PAR1 inhibitor SCH79797, thereby confirming a functional intercellular axis: RELA/NFKB1 – MMP1 (MDA-MB231) – PAR1 (LEC). Recombinant MMP1 induced PAR1-dependent phosphorylation of MLC2 and FAK in LECs, which is indicative for their activity and for directional cell migration such as observed during CCID formation. The combined knock-down of the NF-κB pathways in LECs and MDA-MB231 spheroids inhibited CCIDs significantly stronger than knock-down in either cell type alone. Also the knock-down of ICAM-1 in LECs (a NF-κB endpoint with relevance for CCID formation) and knock-down of MMP1 in MDA-MB231 augmented CCID inhibition. This evidences that in both cell types NF-κB significantly and independently contributes to tumour-mediated breaching of the lymphatic barrier. Hence, inflamed tumour tissue and/or vasculature pose an additional threat to cancer progression.  相似文献   
992.
993.

Background

The study objective was to evaluate the workflow of dental providers who use the existing electronic dental record (EDR) system at a large regional health care system to establish a diagnostic-centric culture as part of their dental practice. A further goal focused on identifying when improvements to the workflow and design of the EDR may be indicated.

Methods

Dental procedures performed on patients and corresponding International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) diagnoses were retrospectively mined from Marshfield Clinic’s enterprise data warehouse. All dental procedures performed were selected and paired with corresponding diagnostic codes documented by dental providers. Frequency of documented diagnosis was further analyzed by characterizing correspondence with their ranking order in the diagnosis column with and without a scroll bar within the EDR user interface (UI). Accuracy of selecting appropriate ICD-9-CM for the corresponding Code on Dental Procedure and Nomenclature (CDT) was checked for 10% (n = 6,187) of the procedure-diagnosis pairs.

Results

Of the 61,511 unique procedures documented using 147 CDTs, 11% (6,914 procedures) had a corresponding “not available” option associated under the diagnoses column, whereas 89% (54,597) of dental procedures were associated with a corresponding ICD-9-CM diagnostic code. Overall tendency of dental providers to select the first or last options from the diagnostic list with a scroll bar was noted. Appropriateness of documenting corresponding ICD-9-CM to CDT procedures indicated 98% accuracy.

Conclusion

EDR UI design greatly affected documentation process. Redesigning the EDR UI from the results will increase both the quality and utility of clinical documentation.  相似文献   
994.
995.
996.
Blindness due to corneal diseases is a common pathology affecting up to 23 million individuals worldwide. The tissue‐engineered anterior human cornea, which is currently being tested in a Phase I/II clinical trial to treat severe corneal trophic ulcers with preliminary good feasibility and safety results. This bioartificial cornea is based on a nanostructured fibrin–agarose biomaterial containing human allogeneic stromal keratocytes and cornea epithelial cells, mimicking the human native anterior cornea in terms of optical, mechanical, and biological behavior. This product is manufactured as a clinical‐grade tissue engineering product, fulfilling European requirements and regulations. The clinical translation process included several phases: an initial in vitro and in vivo preclinical research plan, including preclinical advice from the Spanish Medicines Agency followed by additional preclinical development, the adaptation of the biofabrication protocols to a good manufacturing practice manufacturing process, including all quality controls required, and the design of an advanced therapy clinical trial. The experimental development and successful translation of advanced therapy medicinal products for clinical application has to overcome many obstacles, especially when undertaken by academia or SMEs. We expect that our experience and research strategy may help future researchers to efficiently transfer their preclinical results into the clinical settings.  相似文献   
997.

Introduction

The basis of disc degeneration is still unknown, but is believed to be a cell-mediated process. Apoptosis might play a major role in degenerative disc disease (DDD). The aim of this study was to correlate the viability of disc cells with the radiological degeneration grades (rDG) in disc herniation.

Materials and methods

Forty anterior IVD’s (C4–C7) from 39 patients with DDD were studied histologically and ultrastructurally to quantify healthy, “balloon”, chondroptotic, apoptotic and necrotic cells. Patients were classified to their rDG, as having either prolapse (P: DGII + III) and/or osteochondrosis (O: DGIV + V). Similar studies were undertaken on eight control discs.

Results

Cell death by necrosis (mean 35%) was common but differed not significantly in both groups. All patients with a disc prolapse DGII + III revealed balloon cells (iAF: mean 32%). All appeared alive and sometimes were hypertrophic. However, significantly less balloon cells were found in the O-Group. Control samples revealed no evidence of “balloon” cells in DGII and only a minor rate in DGIII.

Conclusion

According to the different rDG, quantitative changes were obvious in healthy and “balloon” cells, but not for cell death. At the moment it can only be hypothesized if “balloon” cells are part of a repair strategy and/or cause of disc herniation.  相似文献   
998.
Famous people and artifacts are referred to as "unique entities" (UEs) due to the unique nature of the knowledge we have about them. Past imaging and lesion experiments have indicated that the anterior temporal lobes (ATLs) as having a special role in the processing of UEs. It has remained unclear which attributes of UEs were responsible for the observed effects in imaging experiments. In this study, we investigated what factors of UEs influence brain activity. In a training paradigm, we systematically varied the uniqueness of semantic associations, the presence/absence of a proper name, and the number of semantic associations to determine factors modulating activity in regions subserving the processing of UEs. We found that a conjunction of unique semantic information and proper names modulated activity within a section of the left ATL. Overall, the processing of UEs involved a wider left-hemispheric cortical network. Within these regions, brain activity was significantly affected by the unique semantic attributes especially in the presence of a proper name, but we could not find evidence for an effect of the number of semantic associations. Findings are discussed in regard to current models of ATL function, the neurophysiology of semantics, and social cognitive processing.  相似文献   
999.

Background

To achieve T-downstaging and better resectability in locally advanced rectal cancer, neoadjuvant radiochemotherapy (RCT) has become the current standard of treatment. A variety of schemes have been used. This study investigates which scheme had the best effect on these parameters.

Methods

Our institution is a referral center for locally advanced rectal cancer. Different neoadjuvant radiochemotherapy regimens were administered: long course radiotherapy (RTH), 5-FU and leucovorin (5FUBolus), a combination of capecitabine and oxaliplatin (CORE), and capecitabine only (CAP). Selection of patients for 1 of the regimens was based on hospital policy rather than patient or tumor characteristics.

Results

The data of 504 consecutive patients (n?=?181 T3+, n?=?323 T4) without metastatic disease (cM0) who underwent surgery for advanced rectal carcinoma between 1994 and 2010 were reviewed. The RTH, 5FUBolus, CORE, and CAP scheme were administered to 106, 137, 155, and 106 patients, respectively. Odds ratios for downstaging were less effective for RTH, 5FUBolus, and CAP (0.31, 0.44, and 0.31; P?P?=?.003) or CRM+ resection (3.78, 2.73, 1.34; P?=?.001) were also in favor of the CORE. Hazard ratios for CSS were significantly better for the CORE scheme.

Conclusions

Downstaging with neoadjuvant treatment results in an increased number of radical resections. In our study, the combination of capecitabine and oxaliplatin appears to be the most effective regimen for locally advanced rectal cancer tumors. However, longer follow-up will be necessary to confirm this conclusion.  相似文献   
1000.
IntroductionPulmonary nocardiosis (PN) is a severe infection with a high morbidity and mortality that mainly affects immunocompromised patients. In recent years, an increase in PN cases has been detected among patients with chronic obstructive pulmonary disease (COPD). The factors that are associated with its presence and determine its prognosis remain unknown.MethodsRetrospective study of COPD patients diagnosed with PN over the period from 1997 to 2009 at the Hospital de la Santa Creu i Sant Pau, in Barcelona (Spain). Demographic, clinical, microbiological and evolution data were evaluated in all cases.ResultsThirty patients were identified with PN and COPD. Mean age (standard deviation) was 76 (7) years and the mean FEV1 was 40 (14)%. Chronic respiratory failure was observed in 56.7% patients and 51.7% had received systemic corticosteroid therapy previous to the PN diagnosis. The most common symptoms were cough and dyspnea (90%). Alveolar infiltrates were observed in 60% of the cases. The most frequently isolated Nocardia species was N. cyriacigeorgica (68%). The one-month mortality rate was 17%, while the one-year mortality rate was 33%. The factors associated with mortality within the first year included previous systemic corticosteroid treatment, less than three months of specific antibiotic therapy and active associated neoplasm.ConclusionsPN affects patients with moderate-severe COPD and has high short- and mid-term mortality rates. Previous corticosteroid treatment, specific antibiotic therapy for less than 3 months and active neoplasia were factors associated with mortality.  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