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   1140篇
  免费   46篇
  国内免费   97篇
耳鼻咽喉   25篇
儿科学   44篇
妇产科学   12篇
基础医学   87篇
口腔科学   22篇
临床医学   173篇
内科学   273篇
皮肤病学   13篇
神经病学   82篇
特种医学   158篇
外科学   113篇
综合类   42篇
预防医学   85篇
眼科学   7篇
药学   105篇
肿瘤学   42篇
  2021年   12篇
  2019年   8篇
  2018年   9篇
  2017年   8篇
  2016年   7篇
  2015年   13篇
  2014年   23篇
  2013年   32篇
  2012年   38篇
  2011年   20篇
  2010年   36篇
  2009年   44篇
  2008年   46篇
  2007年   79篇
  2006年   43篇
  2005年   69篇
  2004年   28篇
  2003年   41篇
  2002年   29篇
  2001年   35篇
  2000年   26篇
  1999年   20篇
  1998年   46篇
  1997年   39篇
  1996年   30篇
  1995年   33篇
  1994年   30篇
  1993年   42篇
  1992年   15篇
  1991年   20篇
  1990年   20篇
  1989年   34篇
  1988年   36篇
  1987年   29篇
  1986年   29篇
  1985年   28篇
  1984年   14篇
  1983年   12篇
  1982年   9篇
  1980年   17篇
  1979年   12篇
  1978年   11篇
  1977年   11篇
  1976年   7篇
  1975年   11篇
  1974年   12篇
  1973年   14篇
  1971年   10篇
  1970年   7篇
  1969年   7篇
排序方式: 共有1283条查询结果,搜索用时 31 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.
Troponin T levels have been monitored in baboons (n = 8) undergoing pig heterotopic heart transplantation, and correlated with a decrease in graft contractions and graft survival. Pig heart graft survival was from 12 to 139 days (mean 45, median 33), and graft failure was associated with predominant thrombotic microangiopathy and ischemia, with focal hemorrhage, and edema. An increase in troponin T levels 5 to 6 days before graft failure correlated closely with diminished graft contractions. An increase in troponin T was a reliable indicator that graft dysfunction was occurring.  相似文献   
4.
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   
5.
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   
6.
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   
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.
As unilateral nephrectomy (UNX) is associated with enhanced mercuric chloride nephrotoxicity, studies were undertaken to characterize the effects of UNX on the tissue content, urinary excretion, and renal cortical subcellular distribution of mercury in the rat. Animals were studied immediately, 2 days or 14 days following UNX, during separate phases of compensatory renal hypertrophy. As compared to sham surgery controls, mercury content in renal cortex was higher in all UNX groups at 24 hr following injection and in the immediate and 2-day groups at 1 or 3 hr. However, UNX was not associated with any alteration in mercury content within outer or inner medulla, liver, plasma, or red blood cells. Subcellular distribution studies demonstrated that cytosolic mercury was uniformly elevated in all UNX groups at 1, 3, and 24 hr following injection while mercury bound to "metallothionein-like" proteins or free in the cytosol was increased only at 1 or 3 hr. Nuclear, mitochondrial, or microsomal mercury content was elevated in the animals studied immediately or 14 days after UNX at 3 or 24 hr following injection, while animals studied 2 days after UNX demonstrated a nearly uniform increase at 1, 3, and 24 hr. Single-kidney urinary mercury excretion was elevated in all UNX groups while excretion per gram kidney weight was increased only in the animals studied immediately or 2 days after surgery. These studies suggest that all phases of compensatory renal hypertrophy are associated with an enhanced content of mercury within the cell cytoplasm and in critical cellular organelles, which may explain the enhanced nephrotoxicity seen following UNX.  相似文献   
10.
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   
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