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   6938篇
  免费   511篇
  国内免费   31篇
耳鼻咽喉   75篇
儿科学   176篇
妇产科学   150篇
基础医学   1045篇
口腔科学   84篇
临床医学   723篇
内科学   1673篇
皮肤病学   83篇
神经病学   597篇
特种医学   169篇
外国民族医学   3篇
外科学   1141篇
综合类   21篇
一般理论   2篇
预防医学   606篇
眼科学   112篇
药学   398篇
中国医学   3篇
肿瘤学   419篇
  2023年   37篇
  2022年   67篇
  2021年   232篇
  2020年   102篇
  2019年   216篇
  2018年   244篇
  2017年   146篇
  2016年   133篇
  2015年   191篇
  2014年   205篇
  2013年   317篇
  2012年   453篇
  2011年   447篇
  2010年   269篇
  2009年   225篇
  2008年   366篇
  2007年   368篇
  2006年   396篇
  2005年   311篇
  2004年   310篇
  2003年   279篇
  2002年   255篇
  2001年   162篇
  2000年   160篇
  1999年   146篇
  1998年   50篇
  1997年   60篇
  1996年   32篇
  1995年   37篇
  1994年   29篇
  1993年   31篇
  1992年   127篇
  1991年   105篇
  1990年   85篇
  1989年   84篇
  1988年   72篇
  1987年   78篇
  1986年   74篇
  1985年   70篇
  1984年   54篇
  1983年   49篇
  1981年   23篇
  1980年   23篇
  1979年   40篇
  1978年   26篇
  1977年   29篇
  1974年   32篇
  1973年   34篇
  1972年   25篇
  1971年   26篇
排序方式: 共有7480条查询结果,搜索用时 62 毫秒
91.
To examine potential predictors of cancer patient satisfaction with physician behavior, 366 cases were studied. Physician behavior was measured on morning rounds using the Physician Behavior Check List (PBCL). Patient satisfaction and perceptions were assessed after the visit. Patient characteristics were obtained from the chart and the physician. Results showed wide variation in physician behavior; no "standard" set of behaviors was seen in all interactions. Patient satisfaction was high (mean = 87.8 mm on a 100-mm scale). Path analysis showed four variables predicted 62% of the variance in patient satisfaction. The strongest predictor was the patient perception item, "perception of needs addressed that day." Other predictors were perception of emotional support provided by the physician, age (older), and one physician behavior, "discusses treatment." Patient perceptions of needs met or emotional support provided were predicted by perceptions of the occurrence of physician behaviors involving information such as the diagnosis and tests and treatment. Overall, patient perceptions of physician behaviors were stronger predictors of patient satisfaction than the actual occurrence or absence of those behaviors.  相似文献   
92.
93.
The aim of this study was to assess the accuracy and utility of administrative health data in identifying persons with inflammatory bowel disease on a population basis and to determine the incidence and prevalence of this disease in the Canadian province of Manitoba. The data from Manitoba Health (the province's single insurer) were used to identify residents with physician and/or hospital contacts for Crohn's disease or ulcerative colitis based on International Classification of Diseases, Ninth Revision, Clinical Modification, codes between 1984 and 1995. Of 5,182 eligible individuals, 4,514 were mailed questionnaires and 2,725 responded. Cases were defined as individuals with five or more separate medical contacts with one of these diagnoses or three or more such contacts if they were resident for less than 2 years. The accuracy of the study case definitions was high when compared with either self-report or chart review. The 1989-1994 age- and sex-adjusted annual incidence was 14.6/100,000 for Crohn's disease and 14.3/100,000 for ulcerative colitis. The prevalence of Crohn's disease in 1994 was 198.5/100,000, and that of ulcerative colitis was 169.7/100,000. In conclusion, the authors have successfully established and validated a population-based database of inflammatory bowel disease based on administrative data. The high incidence rates and dynamic epidemiology of inflammatory bowel disease in Manitoba indicate the presence of important environmental risk factors, which warrants further investigation.  相似文献   
94.
95.
BACKGROUND: Focal osteolysis due to ultra-high molecular weight polyethylene wear debris involves effects on both bone resorption and bone formation. METHODS: The response of MG63 osteoblast-like osteosarcoma cells to ultra-high molecular weight polyethylene wear debris isolated by enzymatic digestion of granulomatous tissue obtained from the sites of failed total hip arthroplasties was examined. Scanning electron microscopy, particle-size analysis, and Fourier transform infrared spectroscopy were used to characterize the number, morphology, size distribution, and chemical composition of the particles. Cell response was assessed by adding particles at varying dilutions to confluent cultures and measuring changes in cell proliferation (number of cells and [3H]-thymidine incorporation), osteoblast function (alkaline-phosphatase-specific activity and osteocalcin production), matrix production (collagen production and proteoglycan sulfation), and local cytokine production (prostaglandin-E2 production). RESULTS: The mean size of the particles was 0.60 micrometer, and 95 percent of the particles had a size of less than 1.5 micrometers. The number of particles per gram of tissue ranged from 1.39 to 3.38x10(9). Three of the four batches of particles were endotoxin-free. Exposure of the cells to particles of wear debris significantly increased the number of cells (p<0.05) and the [3H]-thymidine incorporation (p<0.05) in a dose-dependent manner. In contrast, the addition of particles decreased alkaline-phosphatase-specific activity and osteocalcin production. Collagen production and proteoglycan sulfation were also decreased, while prostaglandin-E2 synthesis was increased by the addition of particles. CONCLUSIONS: Ultra-high molecular weight polyethylene particles isolated from human tissue stimulated osteoblast proliferation and prostaglandin-E2 production and inhibited cell differentiation and matrix production. These results indicate that particles of wear debris inhibit cell functions associated with bone formation and that osteoblasts may produce factors in response to wear debris that influence neighboring cells, such as osteoclasts and macrophages. CLINICAL RELEVANCE: Particles of wear debris, especially ultra-high molecular weight polyethylene, have been implicated in the loosening of implants and the development of osteolysis. The present study shows that particles of ultra-high molecular weight polyethylene isolated from human tissue inhibit osteoblast functions associated with bone formation. In addition, particles of wear debris induced osteoblasts to secrete factors capable of influencing neighboring cells, such as osteoclasts and macrophages. These results suggest that osteoblasts may play a role in the cascade of events leading to granuloma formation, osteolysis, and failure of orthopaedic implants.  相似文献   
96.
97.
The congenital absence of the portal vein is a rare malformation, which has been generally discovered in association with another anomalies like a cardiac, gastrointestinal or genitourinary defects. With portal hypertension and hepatic cirrhosis, this anomaly is similar to spontaneous porto-systemic derivation, and for that not collateral venous drainage is present. In these patients, total interruption of mesentaric venous drainage during procurement of liver transplant produce a very important bowel and mesenteric edema, which can promote an injert fatal evolution. The authors present the first paediatric liver transplant, in a patient with portal venous agenesia, with de piggy-back technique was done and this complication was obviated, and a review of the literature about this issue is done.  相似文献   
98.
Surgical repair of abdominal wall defects following tumour resection only raises real problems when the nature of the tumour required wide, or even transfixing excision, as in the case of sarcomas or very advanced carcinomas. Superficial repair is performed according to the algorithm of the simplest technique: secondary healing, partial suture, total suture, transplant, or flap (pedicled or free). In the case of transfixing resection, the combination of a biomaterial for reconstruction of the deep plane and a superficial flap is necessary. For very large transfixing defects of the abdomen, a free flap may be required and, in this case, delayed insertion after initial transfer may further reduce the operative risk ("apple turnover" technique). The complications observed in a detailed series of 9 cases operated at Saint-Louis Hospital consisted of one intraoperative cardio-circulatory arrest during second-stage surgery and one late infection at three years. The authors believe that the indications for delayed insertion of a free flap are still very topical in cases in which a very large grafted free flap is necessary in conjunction with a prosthesis. Large abdominal defects after cancer resection can be reconstructed by modern reconstructive surgery.  相似文献   
99.
100.
The hamster intergeniculate leaflet (IGL), part of the circadian rhythm regulatory system, has very extensive interconnections with subcortical visual nuclei. The present investigation describes IGL connections with the hamster diencephalon and telencephalon and compares them with ventral lateral geniculate nucleus (VLG) connections and retinal projections. Connections of the geniculate nuclei were evaluated using anterograde transport of iontophoretically injected Phaseolus vulgaris leucoagglutinin and by retrograde transport of cholera toxin beta fragment. The cholera fragment was also injected intraocularly to trace retinal efferents. The IGL has ipsilateral and contralateral projections to the anterior and posterior hypothalamic nuclei, the ventral preoptic, lateral and dorsal hypothalamic areas, but not to the core ventromedial nucleus and very sparsely to the paraventricular nucleus. There are also IGL projections to the medial and lateral zona incerta, anteroventral, anterodorsal, reuniens, parataenial, paraventricular, centrolateral, central medial, and laterodorsal thalamic nuclei. IGL projections to the telencephalon are found in the horizontal limb of the diagonal band, olfactory tubercle, nucleus of the lateral olfactory tract, posterior bed nucleus of the stria terminalis, ventral pallidum, and in nuclei of the medial amygdala. The only substantial VLG projections are to bed nucleus of the stria terminalis, IGL, medial zona incerta, central medial and laterodorsal thalamic nuclei. Several of the IGL targets, the bed nucleus of the stria terminalis and zona incerta in particular, send projections back to the IGL and VLG. In addition, cells are present in the caudal cingulate cortex that project to both nuclei. Retinal projections are found in many of the regions receiving IGL innervation, including nuclei of the medial basal telencephalon, the posteromedial bed nucleus of the stria terminalis, and nuclei of the hypothalamus. A retinal projection is also visible in the lateral olfactory tract from which it extends rostrally, then medially along the base of the rhinal fissure. Fibers also extend caudally, in a superficial location, to perirhinal cortex. The results further demonstrate the widespread connections of the IGL and support the idea that the IGL modulates olfactory, photic, and circadian rhythm regulation of regulatory physiology and behavior.  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