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   9541篇
  免费   611篇
  国内免费   34篇
耳鼻咽喉   47篇
儿科学   273篇
妇产科学   160篇
基础医学   1858篇
口腔科学   248篇
临床医学   780篇
内科学   1916篇
皮肤病学   293篇
神经病学   1206篇
特种医学   313篇
外科学   830篇
综合类   42篇
一般理论   6篇
预防医学   521篇
眼科学   143篇
药学   584篇
中国医学   19篇
肿瘤学   947篇
  2024年   6篇
  2023年   61篇
  2022年   136篇
  2021年   232篇
  2020年   184篇
  2019年   248篇
  2018年   285篇
  2017年   184篇
  2016年   285篇
  2015年   297篇
  2014年   388篇
  2013年   503篇
  2012年   729篇
  2011年   778篇
  2010年   409篇
  2009年   425篇
  2008年   639篇
  2007年   677篇
  2006年   637篇
  2005年   629篇
  2004年   596篇
  2003年   543篇
  2002年   456篇
  2001年   81篇
  2000年   76篇
  1999年   90篇
  1998年   120篇
  1997年   72篇
  1996年   67篇
  1995年   58篇
  1994年   45篇
  1993年   36篇
  1992年   19篇
  1991年   23篇
  1990年   18篇
  1989年   19篇
  1988年   8篇
  1987年   8篇
  1986年   12篇
  1985年   12篇
  1984年   7篇
  1983年   11篇
  1981年   5篇
  1979年   9篇
  1978年   4篇
  1977年   4篇
  1975年   4篇
  1973年   5篇
  1972年   5篇
  1965年   4篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
Isolated noncompaction of the ventricular myocardium (INVM, MIM 300183 and 604169) is a congenital unclassified cardiomyopathy with numerous prominent trabeculations and deep intertrabecular recesses in a hypertrophied and hypokinetic myocardium. Mutations in the G4.5 gene result in a wide spectrum of severe infantile X-linked cardiomyopathic phenotypes including Barth syndrome with dilated cardiomyopathy and INVM. Molecular genetic analysis of INVM has only been performed in pediatric patients. Although adult INVM patients show similar cardiac abnormalities, the influence of genetic factors, especially of mutations in G4.5, is unknown. We analyzed 25 adult INVM patients for the presence of mutations in the G4.5 gene and performed a pedigree analysis of probands. Mutations were not found in the coding sequence or splice sites of G4.5. Systematic analysis of relatives from seven of nine probands showed multiple affected members consistent with an autosomal dominant pattern of inheritance in the majority of cases. We conclude that INVM in the adult is an autosomal dominant disorder rarely caused by mutations in G4.5 and therefore genetically distinct from infantile X-linked cases.  相似文献   
82.
Dermatoglyphic findings were compared in 42 patients (32 females, 10 males) with Congenital Adrenal Hyperplasia (CAH) and 110 normal controls (70 females, 40 males). In CAH males, an excess of whorls (p less than 0.001), an increased total finger ridge count (p less than 0.05), and an increased frequency of patterns in the fourth interdigital area (p less than 0.025) was found. A main line A terminating high in the hypothenar area (p less than 0.05), and a missing c-triradius or an abortive main line C (p less than 0.05) was observed in CAH females. Both sexes displayed an increase in the frequency of small radially directed hypothenar patterns (p less than 0.05) and sydney lines (p less than 0.01).  相似文献   
83.
Cutaneous manifestations of acute promyelocytic leukemia are rare but well documented. Skin biopsies of leukemia can be difficult to confirm using morphology alone, and paraffin section immunophenotyping is not specific in separating acute promyelocytic leukemia from other acute myeloid leukemias involving the skin or inflammatory conditions, such as Sweet's syndrome and all-trans retinoic acid-associated genital ulcers, which may mimic leukemia cutis. Fluorescence in situ hybridization has been shown to be a fast and effective method of detecting the PML/RARA fusion gene characteristic of acute promyelocytic leukemia in fresh blood and bone marrow samples. Fluorescence in situ hybridization has also been demonstrated to be effective in detecting other chromosomal rearrangements in paraffin-embedded tissue. This retrospective study of cutaneous lesions from four patients with acute promyelocytic leukemia evaluates the utility of performing fluorescence in situ hybridization to confirm the presence of cutaneous manifestations of acute promyelocytic leukemia in formalin-fixed, paraffin-embedded skin biopsies. All patients had previous bone marrow findings of acute promyelocytic leukemia with characteristic morphology, immunophenotype, and cytogenetic studies, which detailed the presence of the t(15;17)(q22;q12) rearrangement. Two skin biopsies showed an infiltrate of blastic cells involving the dermis in a diffuse pattern and one biopsy had a perivascular/periadnexal pattern. The fourth case, involving the scrotum, showed a predominant neutrophilic infiltrate diffusely involving the dermis and epidermis with a subset of blastic cells. Nuclei were extracted from core biopsies of the formalin-fixed paraffin-embedded tissue and fluorescence in situ hybridization was performed using a dual color, dual fusion PML / RARA probe. All cases showed evidence of the t(15;17) rearrangement, with 90, 79, 51 and 16% positive signal patterns, each well above background limits. Fluorescence in situ hybridization appears to be a robust technique to detect cutaneous manifestations of acute promyelocytic leukemia in formalin-fixed paraffin-embedded skin biopsies.  相似文献   
84.
Apoptosis of dentate granule cells is a typical feature of several animal models of disease. In 20 autopsy cases of subarachnoid hemorrhage (SAH) and global cerebral hypoxia caused by protracted shock or respiratory failure, we evaluated by light microscopy and in situ tailing whether this pattern of neuronal damage also occurs in humans. In subarachnoid hemorrhage, 4.0/mm2 (0-13.0/mm2) apoptotic neurons were observed in the dentate gyrus, in cerebral hypoxia 3.6/mm2 (0-19.9/mm2) (p>0.05), and in 10 aged-matched control cases dying rapidly from non-neurological diseases 0/mm2 (0-0/mm2) (median [range]) (p<0.001 versus SAH and hypoxia). Neuronal apoptosis in the dentate gyrus was most frequent, when death occurred later than 24 hours and less than 11 days after disease onset. Neuronal damage in the hippocampus was always necrotic. It was more severe in hypoxia than in SAH (median neuronal damage score 3 [range: 0-3] versus 0 [0-3], p<0.001). Apoptosis appears to be the predominant mechanism of death in dentate granule cells irrespective of the underlying disease, whereas neuronal death in the hippocampus generally is of necrotic morphology.  相似文献   
85.
The permanent human cell line C3842 was established from a secondary chondrosarcoma in a typical case of Olliers disease. In the present study, we analyzed the morphological, cytogenetic and molecular biological characteristics of the cultured cells in comparison with the original tumor and investigated the invasion properties of the tumor model using functional imaging of proteolysis, matrigel assay and chick chorioallantoic membrane assay. C3842 cells exhibit the typical features of malignant cartilage tumor cells in vitro, including the expression of collagen types II, IX, XI and aggrecan. The proteolytic ability of C3842 cells is attributed to the expression of several proteases, such as cathepsin B, urokinase plasminogen activator and matrix-metalloproteinase-2, which enable the cells to degrade collagen type I and to permeate matrigel matrix. In accordance with the biological features in vivo, C3842 cells are not able to invade through the epithelium of the chick chorioallantoic membrane. In conclusion, the cell line C3842 provides the first model of a secondary chondrosarcoma in Olliers disease in vitro, which is characterized by distinct features of such malignant cartilage tumors.  相似文献   
86.
BACKGROUND: Detection of allergen-specific IgE antibodies in patients' sera plays a key role for the diagnosis of IgE-mediated allergy. If no validated test system is available, diagnostic tools must be developed, usually by coupling or binding the allergens to a solid phase. Streptavidin ImmunoCAP is a new solid phase for binding of allergens which can be used in the Pharmacia CAP system. OBJECTIVE: It was the aim of this study to assess the diagnostic validity of Streptavidin ImmunoCAP. METHODS: Biotinylation and allergen concentration for binding to Streptavidin ImmunoCAP were optimized and IgE obtained with natural rubber latex, obeche wood, wheat and rye flour Streptavidin ImmunoCAP were compared with the results of ImmunoCAP and Enzyme Allergo-Sorbent Test (EAST) using sera from patients complaining of workplace-related respiratory symptoms. RESULTS: While the relation of biotin-label and protein was critical (best results were obtained with a 5- fold molar excess), labelled protein for coupling to streptavidin ImmunoCAP was applicable in a wide concentration range. On average, IgE values with streptavidin ImmunoCAP were as high as with ImmunoCAP but considerably higher than values obtained by EAST. CONCLUSION: Streptavidin ImmunoCAP is a valuable tool for sensitive and specific measurement of IgE binding to new allergens superior to cellulose disk-based methods.  相似文献   
87.
88.
Tissue factory is a modular system designed to generate artificial tissues under optimal perfusion culture conditions. The microenvironment within the culture containers can be fine-tuned to meet the physiological needs of individual tissues, so that the generation of differentiated three-dimensional tissue constructs becomes possible. An optimal physiological environment is created by modulating a liquid phase as well as an artificial interstitium surrounding the growing construct. An innovative construction principle allows production of tissue culture containers, gas exchangers, and gas expanders at minimal material expenditure. Therefore it will be possible for the first time to produce sterile one-way perfusion culture modules for the generation of artificial tissues. The modules can be used separately as well as in a combined module. The system is designed to provide a possible platform for the standardized production of artificial tissues for future applications in biomedicine.  相似文献   
89.
90.
46,XY gonadal dysgenesis is characterized by abnormal testicular determination. We describe a large kindred in which various disorders of sexual development were observed, ranging from completely female phenotype without ambiguities of the external genitalia (five cases) to men with isolated penile or perineal hypospadias (four cases), including two cases with moderate virilization and one case with ambiguity of the external genitalia. Histologic examination of gonadal tissue was performed on seven subjects. These findings were suggestive of complete gonadal dysgenesis in one patient, partial gonadal dysgenesis in three patients, and mixed gonadal dysgenesis in three patients. Four patients developed gonadal tumors (two gonadoblastoma, two dysgerminoma, and one immature teratoma, i.e., one patient had a dysgerminoma with some areas of gonadoblastoma). All affected subjects had no other congenital anomalies or dysmorphic features. Analysis of families with several affected individuals with 46,XY gonadal dysgenesis implied an X-linked mode of inheritance because of the apparent absence of male-to-male transmission. However, a sex-limited autosomal dominant mode of inheritance affecting only XY individuals could not be ruled out. Analysis of the pedigree we report indicated an autosomal dominant mode of inheritance because of male-to-male transmission. This kindred supports the involvement of at least one autosomal gene in non-syndromic 46,XY gonadal dysgenesis.  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