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   481004篇
  免费   28547篇
  国内免费   1219篇
耳鼻咽喉   6718篇
儿科学   15303篇
妇产科学   13773篇
基础医学   69543篇
口腔科学   11181篇
临床医学   42089篇
内科学   94352篇
皮肤病学   9154篇
神经病学   39493篇
特种医学   18124篇
外国民族医学   56篇
外科学   74049篇
综合类   10272篇
现状与发展   4篇
一般理论   368篇
预防医学   33502篇
眼科学   11809篇
药学   33086篇
  28篇
中国医学   1039篇
肿瘤学   26827篇
  2021年   5476篇
  2020年   3385篇
  2019年   5520篇
  2018年   7696篇
  2017年   5510篇
  2016年   6481篇
  2015年   7594篇
  2014年   10372篇
  2013年   15883篇
  2012年   20932篇
  2011年   21766篇
  2010年   13381篇
  2009年   12174篇
  2008年   20223篇
  2007年   21836篇
  2006年   21135篇
  2005年   21102篇
  2004年   20146篇
  2003年   18998篇
  2002年   18193篇
  2001年   14817篇
  2000年   14851篇
  1999年   13055篇
  1998年   5398篇
  1997年   4842篇
  1996年   4333篇
  1995年   4115篇
  1994年   3742篇
  1993年   3556篇
  1992年   9339篇
  1991年   9399篇
  1990年   9112篇
  1989年   8899篇
  1988年   8149篇
  1987年   7795篇
  1986年   7549篇
  1985年   7423篇
  1984年   5983篇
  1983年   5275篇
  1982年   4105篇
  1981年   3554篇
  1980年   3415篇
  1979年   5210篇
  1978年   4122篇
  1977年   3526篇
  1975年   3409篇
  1974年   3937篇
  1973年   3831篇
  1972年   3496篇
  1971年   3216篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
Metastatic calcifications according to histopathologic and scintigraphic findings have been well-defined. The authors report a postoperative case of hyperparathyroidism with multiple metastatic calcifications in the lung, kidney, stomach, heart, and vessels that were primarily detected by bone scintigraphy and demonstrated by CT. Tc-99m MDP bone scintigraphy showed a markedly increased accumulation of radioactivity diffusely throughout the lung, left ventricular wall, both kidneys, and the gastric cardia and body. In the lung, plain films showed almost normal lung. CT, however, demonstrated patchy, slightly increased densities in the lung bilaterally. Cardiac CT indicated a considerably increased density of the ventricular myocardium and remarkable calcification in or near the atrioventricular septum or annulus fibrosus. Upper abdominal CT demonstrated increased densities diffusely throughout the gastric mucosa and renal cortex. Only vascular calcifications were depicted by plain films. Using both bone scintigraphy and CT provides accurate information about each lesion and each tissue, allowing precise diagnosis of even a questionable lesion in the early stage of metastatic calcification. Early diagnosis and early therapy offer the best chance for cure or palliative therapy.  相似文献   
992.
Life satisfaction Index Z was administered to 945 persons aged 60 years and over in a community survey in rural and urban locations in South-Western Nigeria. Life Satisfaction Index scores correlated significantly with items on self-assessed health, loneliness, sex (women having a higher mean score) and location. Items that measure social contact, such as marital status, proximity of nearest child, and frequency of seeing close friends, did not correlate at a significant level. Factor analysis produced two factors on varimax rotation and an internal consistency value of 0.72 was obtained. These values are similar to some of those reported in other studies outside Africa.  相似文献   
993.
A prospective randomized study was performed to investigate the effect of surface coating with covalently endpoint–attached heparin (Carmeda Bio Active Surface) and reduced general heparinization on haematological indices and complement C5 activation. Care was taken to optimize the rheological design of the system using centrifugal pump and a closed system without venting or machine suction. Twenty patients scheduled for aortocoronary bypass grafting (EF > 0.5) participated in the study. Ten patients were randomized to be treated with heparin–coated equipment (CBAS) and reduced i.v. heparin (1.5 mg kg-1) while 10 patients treated with identical but noncoated equipment and full heparinization (3 mg–kg-1) served in a Control group. A vacuum suction was used to collect the blood from the operating field and it was autotransfused at weaning from extracorporeal circulation (ECC). Blood samples were obtained from the venous (precircuit) and arterial (postcircuit) side. We used a new and very specific method for detection of C5a based on monoclonal antibodies. The concentration of C5a was low in both groups during the operation but a significant increase was seen on days 1 and 2. In the Control group there was an increase from 10.2 ngml-1±1.2 to 27.5 ng ml-1 ± 4.8 on day 2 and in the CBAS group from 10.7 ng ml-1 ± 1.2 to 35.6 ng ml-1 ± 11.6 on day 2 (NS between groups). The granulocytes and total leukocyte count increased at the end of ECC and was maintained at the elevated level throughout the study period. The amount of free haemoglobin was high in the autotransfused blood in both groups. The present results confirm the feasibility of reducing general heparin when using heparin–coated systems but the study does not support the superiority of such coating with regard to biocompatibility in short procedures with a Theologically optimized circuit. The potential benefit from reduced heparin and protamine has not been fully evaluated.  相似文献   
994.
The work analyses the results of the multimodality treatment of 80 patients among whom 20 suffered from endarteritis obliterans and 60 from atherosclerosis obliterans of the lower limb vessels. In the process of complex treatment intravascular laser irradiation of blood (ILIB) was carried out by introducing the light guide into a peripheral vein. In 31 (73.8%) patients with decompensated circulatory disorders in the limbs, a course of ILIB produced a good clinical effect. A positive effect was encountered in 35 (92.1%) of patients with subcompensated circulatory disorders in the lower limbs. The clinical efficacy of ILIB is due to normalization of blood coagulative properties, increase of the fibrinolytic potential, improvement of hemorheology, and normalization of the lipoprotein ratio.  相似文献   
995.
The baroreflex maintains blood pressure through the glossopharyngeal (IX) cranial nerve. We report a 54-year-old man who developed a left sided headache, hoarseness, dysarthria, dysphagia, and sustained hypertension from a left internal carotid artery dissection. We hypothesise that interruption of the left IX nerve caused hypertension in this patient.  相似文献   
996.
997.
Spontaneous disappearance of an intracranial aneurysm after subarachnoid hemorrhage is an uncommon event and usually associated with severe cerebral vasospasm, giant aneurysms or the use of antifibrinolytics. We present a young woman who suffered a grade 5 subarachnoid hemorrhage with severe vasospasm caused by a small anterior communicating artery aneurysm. The patient underwent a slow recovery and two years later requested surgery. Angiography demonstrated complete disappearance of the aneurysm. The neurosurgeon should be aware that spontaneous thrombosis of cerebral aneurysms can occur and ensure that angiography is repeated when surgery is significantly delayed.  相似文献   
998.
999.
Mammalian response to subdermal implantation of textured microimplants   总被引:4,自引:0,他引:4  
The development of small, textured implant particles suspended in a hydrogel has allowed for subdermal injection therapy to fill tissue defects. The microimplant particles were placed subdermally into the ears of white New Zealand rabbits in order to characterize the foreign body response and the permanence of the implant. Serial micrometer readings were performed on the implant sites to determine any change in thickness of the augmentation following baseline measurement. An initial increase in the thickness was noted approximately 20–30 days postimplantation, as expected. A stable thickness was noted for the remainder of the experiment. Serial histological sections were performed at irregular intervals from one week to one year. Histology demonstrated a mild foreign body response with collagen surrounding each individual microimplant particle. The response was stable after 30–40 days and has remained stable for over one year. It was determined that the histology demonstrated a Boros IA type, or nonimmunogenic, low-turnover foreign body reaction.  相似文献   
1000.
Myofibroblasts and the progression of diabetic nephropathy   总被引:23,自引:3,他引:20  
Background. The cellular mediators of progressive renal fibrosis in diabetic nephropathy remain unknown. Myofibroblasts have been implicated in the pathogenesis of experimental and clinical renal fibrosis. Their role in the progression of diabetic nephropathy is the subject of this study.Subjects and methods. We have studied by immunohistochemistry the expression of cytoskeletal proteins associated with the activation of myofibroblasts; &agr;-smooth-muscle actin (&agr;-SMA), vimentin (Vi) and desmin (D), in the kidneys of 25 patients with diabetic nephropathy (5 patients with diabetic nephropathy (5 patients had a superimposed glomerulonephritis). Comparisons were made with normal tissue for three kidneys removed for renal-cell carcinoma. Correlations were studied between clinical and biochemical parameters with the expression renal cytoskeletal proteins. Results. In normal kidneys, cells expressing &agr;-SMA were confined to the vascular media and adventia while immunoreactive Vi was detected in glomerular epithelial cells. In diabetic kidneys, cells expressing &agr;-SMA were detected primarily in the renal interstitium and to a lesser extent in some glomeruli in association with mesangial proliferation. Vimentin immunostain decreased in glomeruli displaying diabetic hyalinosis and sclerosis. By contrast, strong Vi immunoreactivity was noted in atrophic diabetic tubules and to a lesser extent in the interstitium. Desmin was not detected in either normal or diabetic kidneys. Close correlations were observed between the expression of renal cytoskeletal proteins and the progression of renal insufficiency. Interstitial &agr;-SMA proved to be a predictor of progressive diabetic nephropathy (R2 for 1/serum Cr slope=0.608, P=0.00001). This predictive parameters; tubular atrophy (R2=0.477, P=0.00004) and interstitial fibrosis (R2=0.28, P=0.001). Conclusion. We have demonstrated in this study the neoexpression of cytoskeletal proteins within diabetic kidneys. This has allowed the identification of new predicting histological markers for the progression of diabetic nephropathy.  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