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   2189篇
  免费   146篇
  国内免费   24篇
耳鼻咽喉   36篇
儿科学   100篇
妇产科学   87篇
基础医学   231篇
口腔科学   49篇
临床医学   170篇
内科学   587篇
皮肤病学   107篇
神经病学   150篇
特种医学   87篇
外国民族医学   1篇
外科学   345篇
综合类   21篇
预防医学   152篇
眼科学   26篇
药学   93篇
中国医学   8篇
肿瘤学   109篇
  2023年   9篇
  2022年   19篇
  2021年   47篇
  2020年   35篇
  2019年   50篇
  2018年   64篇
  2017年   45篇
  2016年   44篇
  2015年   52篇
  2014年   70篇
  2013年   96篇
  2012年   142篇
  2011年   122篇
  2010年   81篇
  2009年   98篇
  2008年   102篇
  2007年   106篇
  2006年   91篇
  2005年   94篇
  2004年   114篇
  2003年   96篇
  2002年   83篇
  2001年   54篇
  2000年   96篇
  1999年   68篇
  1998年   36篇
  1997年   35篇
  1996年   36篇
  1995年   27篇
  1994年   31篇
  1993年   12篇
  1992年   34篇
  1991年   33篇
  1990年   18篇
  1989年   15篇
  1988年   23篇
  1987年   17篇
  1986年   21篇
  1985年   15篇
  1984年   13篇
  1983年   9篇
  1982年   15篇
  1981年   8篇
  1979年   7篇
  1978年   8篇
  1977年   7篇
  1976年   7篇
  1975年   8篇
  1974年   7篇
  1971年   8篇
排序方式: 共有2359条查询结果,搜索用时 265 毫秒
81.
82.
Obscure gastrointestinal bleeding is a common disorder and may account for as many as 5% of all gastrointestinal hemorrhages. It is often caused by lesions in the small intestine, which were very complicated to examine prior to the advent of wireless capsule endoscopy. Here we present the case of a 31-year-old woman with obscure gastrointestinal bleeding as a complication of radiation enteritis, which was diagnosed only after she underwent an examination with wireless capsule endoscopy. This technique has proven to be far superior to other radiographic and endoscopic methods in diagnosing obscure gastrointestinal bleeding and pathologies of the small intestine in general.  相似文献   
83.
The goal of this phase II multicenter clinical trial was to evaluate a new intensive chemotherapy program for adults with untreated acute lymphoblastic leukemia (ALL) and to examine prospectively the impact of clinical and biologic characteristics on the outcome. One hundred ninety-seven eligible and evaluable patients (16 to 80 years of age; median, 32 years of age) received cyclophosphamide, daunorubicin, vincristine, prednisone, and L-asparaginase; 167 patients (85%) achieved a complete remission (CR), 13 (7%) had refractory disease, and 17 (9%) died during induction. A higher CR rate was observed in younger patients (94% for those < 30 years old, 85% for those 30 to 59 years old, and 39% for those > or = 60 years old, P < .001) and in those who had a mediastinal mass (100%) or blasts with a T-cell immunophenotype. Eighty percent of B-lineage and 97% of T-cell ALL patients achieved a CR (P = .01). The coexpression of myeloid antigens did not affect the response rate or duration. Seventy percent of those with cytogenetic or molecular evidence of the Philadelphia (Ph) chromosome and 84% of those without such evidence achieved a CR (P = .11). Patients in remission received multiagent consolidation treatment, central nervous system prophylaxis, late intensification, and maintenance chemotherapy for a total of 24 months. After a median follow-up time of 43 months, the median survival for all 197 patients is 36 months; the median remission duration for the 167 CR patients is 29 months. Favorable pretreatment characteristics relative to remission duration or survival are younger age, the presence of a mediastinal mass or lymphadenopathy, a white blood cell count (WBC) less than 30,000/microL, L1 morphology, T or TMy immunophenotype, and the absence of the Ph chromosome. The estimates of the proportion surviving at 3 years are 69% for patients less than 30 years old, 39% for those 30 to 59 years old, 89% for those who had a mediastinal mass, 59% with WBC less than 30,000/microL, 63% with L1 morphology, 69% for T or TMy antigen expression, and 62% for those who lack the Ph chromosome. Fifteen patients (8%) had no unfavorable prognostic factors and have an estimated probability of survival at 5 years of 100% (95% confidence interval, 77% to 100%). This intensive chemotherapy regimen produces a high remission rate and a high proportion of durable remissions in adults with ALL.  相似文献   
84.
85.
86.
87.
Refractive errors are common eye disorders characterized by a mismatch between the focal power of the eye and its axial length. An increased axial length is a common cause of the refractive error myopia (nearsightedness). The substantial increase in myopia prevalence over the last decades has raised public health concerns because myopia can lead to severe ocular complications later in life. Genomewide association studies (GWAS) have made considerable contributions to the understanding of the genetic architecture of refractive errors. Among the hundreds of genetic variants identified, common variants near the gap junction delta-2 (GJD2) gene have consistently been reported as one of the top hits. GJD2 encodes the connexin 36 (Cx36) protein, which forms gap junction channels and is highly expressed in the neural retina. In this review, we provide current evidence that links GJD2(Cx36) to the development of myopia. We summarize the gap junctional communication in the eye and the specific role of GJD2(Cx36) in retinal processing of visual signals. Finally, we discuss the pathways involving dopamine and gap junction phosphorylation and coupling as potential mechanisms that may explain the role of GJD2(Cx36) in refractive error development.  相似文献   
88.
OBJECTIVE: Ghrelin, the endogenous ligand of growth hormone secretagogue receptor (GHS-R), acts on the pituitary and the hypothalamus to stimulate the release of growth hormone (GH) and promotes appetite and adiposity. It has also been reported to increase myocardial contractility, induce vasodilation, and protect against myocardial-infarction-induced heart failure. Though principally gastric in origin, it is also produced by other tissues. This work investigated whether cardiomyocytes synthesize and secrete ghrelin, and how its production in these cells responds to stress and exogenous apoptotic agents. METHODS: Ghrelin and its receptor expression was studied by RT-PCR, immunohistochemistry, and competitive binding studies in mouse adult cardiomyocyte cell line HL-1, and primary cultured human cardiomyocytes. Ghrelin accumulation in cardiomyocyte culture medium was measured by radioimmunoassay. Viability and apoptosis assays were carried on by MTT and Hoechst dye vital staining, respectively. RESULTS: RT-PCR showed that HL-1 cells produce mRNAs for both ghrelin and GHS-R, and that GHS-R1a is expressed in human cardiomyocytes; and competitive binding studies using (125)I-labelled ghrelin showed efficient constitutive expression of GHS-R at the surface of HL-1 cells. Immunohistochemistry confirmed the presence of ghrelin in the cytoplasm of HL-1 cells and of isolated human cardiomyocytes in primary culture. Radioimmunoassay showed that ghrelin was secreted by HL-1 cells and human cardiomyocytes into the culture medium. Ghrelin did not modify the viability of HL-1 cells subjected to 12-h starvation, but did protect against the apoptosis inducer cytosine arabinoside (AraC). Finally, production of ghrelin mRNA in HL-1 cardiomyocytes was reduced by AraC but increased if exposure to AraC was preceded by GH treatment. CONCLUSIONS: Ghrelin is synthesized and secreted by isolated murine and human cardiomyocytes, probably with paracrine/autocrine effects, and may be involved in protecting these cells from apoptosis.  相似文献   
89.
Helical computerized tomography (CT) and magnetic resonance imaging (MRI) are used for staging of hepatocellular carcinoma (HCC) prior to curative treatments but underestimate tumor extension in 30% to 50% of cases when compared with pathologic explants. This study compares a new technology, MRI angiography (MRA), with triphasic helical CT in detection of HCC. Fifty cirrhotic patients, 29 with HCC, undergoing liver transplantation were analyzed. MRA was performed with a 3-D breath-hold fast spoiled gradient-echo sequence by using an effective section thickness of 2 to 2.5 mm. The gold standard was the pathologic examination (liver cut into 5-mm slices). One hundred twenty-seven lesions were identified at the explant: 76 HCC, 13 high-grade dysplastic nodules, 31 macroregenerative nodules, 7 hemangiomas. Diameter of the main HCC nodules was 29 +/- 14 mm and 11 +/- 7 mm for the 47 additional nodules. On a per nodule basis, sensitivity of MRA was superior to CT (58/76 [76%] vs. 43/70 [61%], respectively, P =.001). Sensitivity of MRA for detection of additional nodules decreased with size (>20 mm: 6/6 [100%]; 10-20 mm: 16/19 [84%]; <10 mm: 7/22 [32%]) and was superior to CT for nodules 10 to 20 mm (84% vs. 47%, P =.016). Nonspecific hypervascular nodules >5 mm at MRA were HCC in two thirds of the cases. In conclusion, MRA has a high diagnostic accuracy for HCC > or =10 mm and is more sensitive than triphasic helical CT in nodules sized 10 to 20 mm. MRA is the optimal technique for HCC staging prior to curative therapies.  相似文献   
90.
ObjectiveTo describe the essential components of well-resourced and high-functioning multidisciplinary networks that support high-quality anesthesia, surgery, and maternity care for rural Canadians, delivered as close to home as possible.Composition of the committeeA volunteer Writers’ Group was drawn from the Society of Obstetricians and Gynaecologists of Canada, the Society of Rural Physicians of Canada, the Royal College of Physicians and Surgeons of Canada, the Canadian Association of General Surgeons, the College of Family Physicians of Canada, and the Association of Canadian University Departments of Anesthesia.MethodsA collaborative effort over the past several years among the professional stakeholders has culminated in this consensus statement on networked care designed to integrate and support a specialist and non-specialist, urban and rural, anesthesia, surgery, and maternity work force into high-functioning networks based on the best available evidence.ReportSurgical and maternity triage needs to be embedded within networks to address the tensions between sustainable regional programs and local access to care. Safety and quality must be demonstrated to be equivalent across similar patients and procedures, regardless of network site. Triage of patients across multiple sites is a quality outcome metric requiring continuous iterative scrutiny. Clinical coaching between rural and regional centres can be helpful in building and sustaining high-functioning networks. Maintenance of quality and the provision of continuing professional development in low-volume settings represent a mutual value proposition.ConclusionThe trusting relationships that are foundational to successful networks are built through clinical coaching, continuing professional development, and quality improvement. Currently, a collaborative effort in British Columbia is delivering a provincial program—Rural Surgical Obstetrical Networks—built on the principles and supporting evidence described in this consensus statement.  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