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   632篇
  免费   26篇
  国内免费   96篇
耳鼻咽喉   2篇
儿科学   42篇
基础医学   54篇
口腔科学   19篇
临床医学   113篇
内科学   149篇
皮肤病学   14篇
神经病学   32篇
特种医学   112篇
外科学   24篇
综合类   36篇
预防医学   29篇
眼科学   7篇
药学   86篇
肿瘤学   35篇
  2023年   3篇
  2022年   2篇
  2021年   8篇
  2020年   3篇
  2019年   9篇
  2018年   6篇
  2017年   7篇
  2016年   6篇
  2015年   6篇
  2014年   10篇
  2013年   21篇
  2012年   13篇
  2011年   11篇
  2010年   28篇
  2009年   27篇
  2008年   14篇
  2007年   60篇
  2006年   18篇
  2005年   29篇
  2004年   5篇
  2003年   10篇
  2002年   9篇
  2001年   21篇
  2000年   7篇
  1999年   9篇
  1998年   43篇
  1997年   39篇
  1996年   29篇
  1995年   29篇
  1994年   27篇
  1993年   38篇
  1992年   6篇
  1991年   10篇
  1990年   16篇
  1989年   30篇
  1988年   29篇
  1987年   17篇
  1986年   19篇
  1985年   17篇
  1984年   9篇
  1983年   4篇
  1982年   8篇
  1981年   5篇
  1980年   11篇
  1979年   3篇
  1978年   5篇
  1977年   7篇
  1976年   3篇
  1969年   3篇
  1968年   1篇
排序方式: 共有754条查询结果,搜索用时 15 毫秒
1.
顺铂聚乳酸微球的药物释放特性及肝动脉栓塞研究   总被引:5,自引:0,他引:5  
对顺铂聚乳酸微球进行了体外药物释放和家犬肝动脉栓塞研究。该微球粒径范围为50~200μm,平均粒径为115.76±35.94μm,顺铂含量为37.16%(W/W);体外药物释放机制符合Higuchi方程;肝动脉栓塞后8h,肝组织顺铂浓度高达21.55±12.18μg/g,明显高于肝动脉灌注顺铂组:3.16±0.09μg/g(P<0.05);肝动脉栓塞组的顺铂血浓峰值、各取血点浓度及曲线下面积AUC皆低于肝动脉灌注顺铂组。可望达到提高栓塞部位的药物疗效,降低全身毒副反应的作用。  相似文献   
2.
Primary tuberculous pathology in nasolpolypi is a rare condition. A case of bilateral ethmoidal polypi with tubercular lesion diagnosed on histopathologlcal examination is being reported and the available relevant literature has been reviewed.  相似文献   
3.
BACKGROUND: Many patients with asthma or chronic obstructive pulmonary diseaseuse their medication inhalers incorrectly. General practitioners,pharmacists and other health care providers do not always havethe opportunity to instruct patients in correct inhaler technique. OBJECTIVE: To find out whether the inhaler technique and respiratory symptomsof patients can be improved after instruction by practice assistants. METHODS: Single blind, randomized intervention study in which 48 patientswho had been using a dry powder inhaler for at least one monthtook part. Their inhaler technique was videotaped on two visitswith a two-week interval between visits. The inhaler techniqueon the videos was subsequently scored by two experts on ninecriteria. At both visits the patients completed a questionnaireabout their respiratory symptoms. After the first video, 25patients were randomly chosen to receive instruction from oneof six practice assistants who had followed a one evening courseabout inhaler instruction, and who had been issued an instruction-set. RESULTS: The patients who received instruction had a significantly greaterreduction in number of mistakes at the second visit than thepatients who did not (P = 0.01). The instructed patients alsoreported less dyspnoea at the second visit (P = 0.03). No effectof instruction was found on wheezing, cough and sputum production. CONCLUSION: The inhaler technique of patients can be improved significantlyby the instruction of patients by trained practice assistants,possibly resulting in less dyspnoea. Keywords. Administration-inhalation, obstructive lung diseases, airways symptoms, patient-education, general practice.  相似文献   
4.
In situ saphenous vein grafts are being used with increasing frequency for bypass procedures involving the femoral and popliteal arteries. Complications of these procedures include anastomotic stenoses and persistent arteriovenous fistulae that may result in failure of the graft. Balloon angioplasty and embolotherapy with detachable balloons were employed successfully in three or four recent cases of patients with complications from in situ grafts. Tailored angiography is essential for evaluating in situ grafts, and interventional techniques are extremely useful for managing complications.  相似文献   
5.
Forty conventional radiographs with examples of mild interstitial infiltrates and subtle pneumothoraces and 40 normal studies of the chest were selected and digitized, with pixel sizes of 1.0, 0.5, 0.2, and 0.1 mm. Observer performance tests were carried out using receiver operating characteristic analysis. Conventional radiographs and digitized images were compared. The results indicate that, in such cases, diagnostic accuracy increases significantly as the pixel size is reduced, at least to the 0.1-mm level. We conclude that, for digital systems using screen-film or similar image receptors, use of a pixel size substantially larger than 0.1 mm may result in some loss of diagnostic accuracy.  相似文献   
6.
Two simultaneous surveys were conducted by the Association of Residents in Radiation Oncology (ARRO). A survey of all residents in Radiation Oncology was conducted to obtain information on trends in residency training. A simultaneous survey of Chief Residents was obtained to determine more specific information on current training programs. Over one-half of residents responded. Eighty-eight percent of respondents were graduates of a North American medical school. Most did at least an internship prior to entering Radiation Oncology and 3/4 of those who did not do a separate internship rotated through other areas at a later time to broaden their knowledge. One-half are Board certified or Board eligible in another specialty or hold a Masters or Ph.D. degree. Three-quarters of all residents had authorship of at least one paper during training and one-half were primary authors. Eighty percent felt adequately prepared for practice after residency. One-half plan at least an initial post-residency affiliation with an academic center. Many were concerned that Radiation Oncologists are not afforded respect equivalent to that of other specialties. Ninety-eight percent favored departmental status for Radiation Oncology. Resident recommendations for improving the image of Radiation Oncology are presented.  相似文献   
7.
BACKGROUND: Growing interest is nowadays focused on the quality of life of elderly people who survive with chronic diseases. Coronary heart disease (CHD) is one of the most common diseases among the elderly and may have an unfavourable impact on the patient's emotional well-being. OBJECTIVES: We aimed to describe the prevalence of depression and the occurrence of depressive symptoms among elderly CHD patients, with a special emphasis on the relations between depression and the severity of CHD, and to find out the possible association between CHD and depression. METHODS: The study was carried out at the health centre of the municipality of Lieto, in south-west Finland. The study population consisted of 488 community-dwelling men and 708 women, over 64 years old, from among whom the participants with CHD (89 men and 73 women) were selected, and for whom 178 male and 146 female sex- and age- matched controls (free of CHD) were drawn from the population. CHD patients were selected on the basis of the presence of angina pectoris or a past myocardial infarction. Depressive symptoms were measured with the Zung Self-rating Depression Scale. Depression was described in relation to the severity of dyspnoea and chest pain among patients. The associations between depression and age, health, health behaviour, drugs, functional ability and social, psychosocial and environmental factors were analysed by logistic regression analyses. RESULTS: The prevalence of depression was 29% among male patients and 20% among female patients. Depression was significantly more common among male CHD patients than among male controls (P = 0.011). Among women, depression was not associated with CHD. Earlier, depression had gone undiagnosed among many CHD patients and controls, especially male patients. Among male CHD patients, depression was associated with more severe dyspnoea, but no similar association was found among female CHD patients. Among men the occurrence of CHD, physical disability, widowhood or divorce, and among women previous clinical depression, physical disability and the use of angiotensin-converting enzyme (ACE) inhibitors, were associated with depression. CONCLUSION: Depression is common among patients with CHD. It seems that CHD is not an independent factor in the aetiology of depression among the elderly. The association of CHD with depression among men is explained by the acute or chronic psychic stress caused by CHD. It may be that the more complicated the patient's CHD, the more probable is the presence of depression.   相似文献   
8.
The renal insulin-like growth factor-I (IGF-I) system has been implicated in the pathogenesis of renal hypertrophy, altered hemodynamics, and extracellular matrix expansion associated with early diabetes. The relative abundance of IGF binding proteins (IGFBPs) in the renal microenvironment may modulate IGF-I actions. However, the precise IGFBPs expressed in the glomerular and tubulointerstitial compartments during diabetic renal growth have not been characterized. In the present study, in situ hybridization studies were performed to examine the expression of IGFBP-1 to -6 messenger RNAs (mRNAs) 3, 7, and 14 days after streptozotocin (STZ) injection in rats. In control, nondiabetic kidneys, all six IGFBP mRNAs were differentially expressed with a predominance of IGFBP-5. The onset of renal hypertrophy in STZ-induced diabetes was associated with a rapid and site-specific induction of IGFBP-1, -3, and -5 mRNAs. In contrast, basal expression of IGFBP-2, -4, and -6 mRNAs was not altered in diabetic rats. IGFBP-5 mRNA expression increased in diabetic glomeruli, cortical, and inner medullary peritubular interstitial cells at days 3, 7, and 14. Although normal glomeruli failed to express IGFBP-3, it was induced concomitantly with IGFBP-5 in diabetic glomeruli and cortical peritubular interstitial cells. IGFBP-1 mRNA levels also increased in cortical tubular cells at each time point tested. Peak induction of IGFBP-3 and -5 was observed at day 3, whereas IGFBP-1 was delayed until day 7. IGFBP-1, -3, and -5 mRNA levels declined by day 14, but remained persistently elevated above control. By immunoperoxidase staining, similar alterations in the pattern of IGFBP-3 and -5 protein expression were observed at each time point. The preferential and site-specific increase in IGFBP-1, -3, and -5 suggest that these IGFBPs may regulate the local autocrine and/or paracrine actions of IGF-I and contribute to the pathogenesis of the early manifestations of diabetic nephropathy.  相似文献   
9.
Multiple sclerosis (MS) is a demyelinating autoimmune disease of the central nervous system. While its etiology is not well understood, genetic factors are clearly involved. Until recently, most genetic studies in MS have been association studies using the case-control design testing specific candidate genes and studying only sporadic cases. The only consistently replicated finding has been an association with the HLA-DR2 allele within the major histocompatibility complex (MHC) on chromosome 6. Using the genetic linkage design, however, evidence for and against linkage of the MHC to MS has been found, fostering suggestions that sporadic and familial MS have different etiologies. Most recently, two of four genomic screens demonstrated linkage to the MHC, although specific allelic associations were not tested. Here, a dataset of 98 multiplex families was studied to test for an association to the HLA-DR2 allele in familial MS and to determine if genetic linkage to the MHC was due solely to such an association. Three highly polymorphic markers (HLA-DR, D6S273 and TNFbeta) in the MHC demonstrated strong genetic linkage (parametric lod scores of 4.60, 2.20 and 1.24, respectively) and a specific association with the HLA-DR2 allele was confirmed (TDT; P < 0.001). Stratifying the results by HLA-DR2 status showed that the linkage results were limited to families segregating HLA-DR2 alleles. These results demonstrate that genetic linkage to the MHC can be explained by the HLA-DR2 allelic association. They also indicate that sporadic and familial MS share a common genetic susceptibility. In addition, preliminary calculations suggest that the MHC explains between 17 and 62% of the genetic etiology of MS. This heterogeneity is also supported by the minority of families showing no linkage or association with loci within the MHC.   相似文献   
10.
Submicroscopic deletions of the Y chromosome and polymorphisms of the androgen receptor (AR) gene in the X chromosome have been observed in men with defective spermatogenesis. To further define the subregions/genes in the Y chromosome causing male infertility and its relationship to polymorphisms of the AR polyglutamine tract, we screened the genomic DNA of 202 subfertile males and 101 healthy fertile controls of predominantly Chinese ethnic origin. Y microdeletions were examined with 16 sequence-tagged site (STS) probes, including the RBM and DAZ genes, spanning the AZFb and AZFc subregions of Yq11, and related to the size of trinucleotide repeat encoding the AR polyglutamine tract. Y microdeletions were detected and confirmed in three out of 44 (6.8%) of azoospermic and three out of 86 (3.5%) severely oligozoospermic patients. No deletions were detected in any of the patients with sperm counts of >0.5 x 10(6)/ml, nor in any of the 101 fertile controls. All six affected patients had almost contiguous Y microdeletions spanning the entire AZFc region including the DAZ gene. The AZFb region, containing the RBM1 gene, was intact in five of the six subjects. Y deletions were not found in those with long AR polyglutamine tracts. Our study, the first in a Chinese population, suggest a cause and effect relationship between Y microdeletions in the AZFc region (possibly DAZ), and azoospermia or near-azoospermia. Y microdeletions and long AR polyglutamine tracts appear to be independent contributors to male infertility.   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