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   420447篇
  免费   28652篇
  国内免费   5919篇
耳鼻咽喉   5633篇
儿科学   8675篇
妇产科学   10642篇
基础医学   57202篇
口腔科学   12473篇
临床医学   35430篇
内科学   83872篇
皮肤病学   8985篇
神经病学   28874篇
特种医学   15469篇
外国民族医学   97篇
外科学   64673篇
综合类   18548篇
现状与发展   19篇
一般理论   69篇
预防医学   21233篇
眼科学   10393篇
药学   35680篇
  50篇
中国医学   4957篇
肿瘤学   32044篇
  2022年   2715篇
  2021年   4602篇
  2020年   3193篇
  2019年   4075篇
  2018年   5894篇
  2017年   4879篇
  2016年   4772篇
  2015年   5917篇
  2014年   8041篇
  2013年   9796篇
  2012年   13245篇
  2011年   13557篇
  2010年   8686篇
  2009年   7965篇
  2008年   11783篇
  2007年   12648篇
  2006年   12392篇
  2005年   11299篇
  2004年   10558篇
  2003年   10545篇
  2002年   9925篇
  2001年   29566篇
  2000年   29668篇
  1999年   24372篇
  1998年   5590篇
  1997年   4673篇
  1996年   4097篇
  1995年   3743篇
  1994年   3339篇
  1993年   2994篇
  1992年   16194篇
  1991年   14947篇
  1990年   14257篇
  1989年   14041篇
  1988年   12642篇
  1987年   12109篇
  1986年   11151篇
  1985年   10355篇
  1984年   6923篇
  1983年   5614篇
  1982年   2725篇
  1979年   5487篇
  1978年   3351篇
  1977年   2978篇
  1975年   2642篇
  1974年   3071篇
  1973年   2871篇
  1972年   2834篇
  1971年   2775篇
  1969年   2546篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
To investigate the role of cell-mediated immunity (CMI) in glomerulonephritis (GN), we identified the infiltrating immune cells both within the glomerulus and in the interstitium. Frozen sections from 103 patients with various forms of GN: 10 with minor glomerular abnormality (MGA) as control, 10 with minimal change nephrotic syndrome (MCNS), 10 with membranous nephropathy (MN), 9 with focal glomerulosclerosis (FGS), 30 with IgA nephropathy (IgAN), 22 with acute post streptococcal glomerulonephritis (APSGN), and 2 with rapidly progressive glomerulonephritis (RPGN) were examined using monoclonal antibodies (MoAb) by indirect immunoalkaline-phosphatase labelling. In most glomerulonephritis, monocyte/M phi and helper/inducer T cells were predominantly infiltrating in the interstitium, but intraglomerular infiltration was rare, except for APSGN. This interstitial infiltration increased proportionally to the level of serum creatinine, and was most prominent in RPGN. Apparently different distribution was seen in APSGN, that is, prominent increase in total number of intra-glomerular monocyte/M phi infiltration with slightly increased T cells. The change was correlated with time after onset; namely the more leucocytic infiltration was observed when the tissue was taken earlier. These data suggest that in APSGN, monocyte/M phi accumulate in glomeruli via cell mediated immunity in addition to humoral immune mechanism resulting in glomerular hypercellularity, whereas in most chronic glomerulonephritis interstitial leucocyte infiltration, particularly helper T cells and monocyte/M phi may play an important role in the progression of glomerulonephritis.  相似文献   
32.
The effects of FUT-187 (6-amidino-2-naphthyl 4-[(4,5-dihydro-1H-imidazol-2-yl)amino]benzoate dimethanesulfonate, CAS 103926-82-5), a novel synthetic protease inhibitor, were examined in experimental rat and canine models of pancreatitis. 1. FUT-187 significantly increased the survival of rats with trypsin- and phospholipase A2-induced pancreatitis in a dose-dependent manner (10-100 mg/kg, p.o.). 2. FUT-187 decreased plasma enzymatic activity reflecting the degree of pancreatitis in rats with ethionine-induced pancreatitis, and showed a tendency to ameliorate histopathological changes in the pancreas (10-100 mg/kg p.o.). 3. FUT-187 (10 mg/kg) produced an obvious improvement of various biochemical parameters of pancreatitis and also reduced histopathological changes in the pancreas in animals with experimental pancreatitis produced by the closed duodenal loop method. In addition, FUT-187 significantly increased the survival of dogs when given by direct administration into the lumen of the closed duodenal loop. The therapeutic effects of FUT-187 in experimental pancreatitis were nearly equal in most instances to those of camostat mesilate. Thus, FUT-187 would appear to be an effective new agent for the treatment of pancreatitis.  相似文献   
33.
Fluorescent model substances of increasing lipophilicity (Oregon Green) 488, Bodipy, FL C5 and Bodipy 564/570 C5) were selected to enable the visualization in the skin using confocal laser scanning microscopy. After measuring the penetration for 18 h, the nonfixed human scalp skin was imaged from the bottom parallel to the stratum corneum and in a cross-section view perpendicular to the skin surface. The images were evaluated by calculating relative accumulation values for different penetrants. The studies indicate that the penetrated amount is highest for Bodipy FL C5 (medium lipophilicity) and lowest for Bodipy 564/570 C5 (high lipophilicity) whereas Bodipy 564/570 C5 (high lipophilicity) reveals the highest relative accumulation in parts of the hair follicle compared to Oregon Green 488 (low lipophilicity). The addition of 30% (v/v) ethanol to the donor phase of substance with a low lipophilicity increases the follicular delivery. From our results we conclude that delivery to the hair follicle can be improved by increasing the drugs lipophilicity and optimizing the composition of the donor phase. However, no conclusion can be drawn about the actual route of transport to the hair follicle.  相似文献   
34.
A 70-year-old woman developed left hypoglossal nerve palsy, a right hemiparesis sparing the face, and a typical left Wallenberg's syndrome. These symptoms resulted from a lesion in the left half of the medulla oblongata, suggesting Babinski-Nageotte syndrome, a rare cerebrovascular disease. This is the first case of ischemic infarction in the territory of the left vertebral artery and posterior inferior cerebellar artery demonstrated on magnetic resonance imaging. Severe bilateral lesions of the distal vertebral arteries demonstrated on digital subtraction angiography may have contributed to the development of this syndrome.  相似文献   
35.
The presence of cytochrome P-45011 beta in rat brain was studied by immunohistochemistry using polyclonal rabbit antibodies raised against purified bovine adrenocortical P-45011 beta, which is involved in the steroid 11 beta-hydroxylation and glucocorticoid formation. The results showed that cytochrome P-45011 beta immunoreactivity is selectively localized to the tracts of myelinated fibers throughout the brain. The specificity of immunohistochemical stainings with P-45011 beta antibodies was established by control tests including nonimmune rabbit immunoglobulin Gs and P-45011 beta antibodies absorbed with purified antigen. Western immunoblots of homogenates from different brain areas with P-45011 beta antibodies, together with biochemical enzymatic assays for cytochrome P-45011 beta monooxygenase activity in these homogenates, confirmed the selective localization of this enzyme observed with immunohistochemistry. Cytochrome P-45011 beta and 11 beta-hydroxylase activity were detected in a homogenate from the cortical white matter (brain area rich in myelinated fibers) as in that from the rat adrenal, but were not detectable in a homogenate from the cerebral cortex (brain area poor in myelinated fibers). Furthermore, quantitation of the P-45011 beta bands on the immunoblots by the areal density revealed that the cortical white matter contains approximately 1.4 pmol of cytochrome P-45011 beta/mg of tissue protein, the value of which was about one sixth of the corresponding value estimated in the rat adrenal. This relatively high content of cytochrome P-45011 beta was also reflected in a relatively high level of 11 beta-hydroxylase activity measured in a homogenate of this brain area by biochemical enzymatic assays using [4-14C]-11-deoxycorticosterone.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
36.
Although the human tumor clonogenic assay (HTCA) is extremely reliable in determining clinical correlations, it is a complicated process requiring considerable time in order to obtain results. Thus, an experimental study on cytopathologic observation (cytologic assay) and comparative evaluation between it and HTCA were performed in order to establish a more rapid and accurate drug sensitivity test. Materials included Colon 26, a cell line established in our department, malignant effusion and surgical specimens. In carrying out HTCA according to the Hamburger-Salmon method, the cell suspension samples following exposure to anti-tumor agents (MMC, L-PAM, ADM, CDDP) were cultivated in test tubes for 3-8 hours and stained by the Papanicolaou and Giemsa methods. According to Tokita's criteria, when cellular changes showed as nuclear pyknosis and nuclear destruction were found to have increased significantly in comparison with a control group, the cells were judged to be sensitive. Very similar and parallel results were obtained between HTCA and cytologic assay in this study, with a significant correlation. Cytologic assay was proved to be an easy, rapid and accurate method for testing drug sensitivity and its clinical application can be expected in the future.  相似文献   
37.
IgG-maleimide peroxidase, Fab'-maleimide peroxidase, polymer and monomer types of Fab'-periodate peroxidase were prepared from an antibody against rat lipoamide dehydrogenase, a component of the pyruvate dehydrogenase complex which is located in mitochondria. They were examined for immunohistochemical staining of the rat kidney. Fab'-maleimide peroxidase was the best for staining mitochondrial protein. IgG-maleimide peroxidase and the monomer type of Fab'-periodate peroxidase had the same intensity of staining. The polymer type of Fab'-periodate peroxidase could not stain the lipoamide dehydrogenase.  相似文献   
38.
39.
40.
Carnitine status in Reye and Reye-like syndromes   总被引:4,自引:0,他引:4  
Fourteen children with the following Reye and Reye-like syndromes were studied to determine each patient's carnitine status: valproate-induced Reye-like attack, ornithine transcarbamylase deficiency, systemic carnitine deficiency, methylmalonic acidemia, and propionic acidemia. Reduced free carnitine and increased serum and urine acylcarnitine levels were found in all patients except for 2 with Reye syndrome, in whom serum creatinine levels were mildly elevated and serum free carnitine levels were not reduced. The renal free carnitine reabsorption rate was reduced in all cases. The free carnitine content of autopsied liver samples were reduced in 2 Reye syndrome patients, 2 OTC deficiency patients, and in a single systemic carnitine deficiency patient. The observed secondary free carnitine deficiency may be a factor in the pathogenesis of Reye and Reye-like syndromes.  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