全文获取类型
收费全文 | 10240篇 |
免费 | 571篇 |
国内免费 | 33篇 |
专业分类
耳鼻咽喉 | 99篇 |
儿科学 | 214篇 |
妇产科学 | 127篇 |
基础医学 | 1219篇 |
口腔科学 | 261篇 |
临床医学 | 719篇 |
内科学 | 2700篇 |
皮肤病学 | 202篇 |
神经病学 | 628篇 |
特种医学 | 249篇 |
外科学 | 1722篇 |
综合类 | 47篇 |
预防医学 | 294篇 |
眼科学 | 222篇 |
药学 | 847篇 |
中国医学 | 36篇 |
肿瘤学 | 1258篇 |
出版年
2023年 | 60篇 |
2022年 | 105篇 |
2021年 | 194篇 |
2020年 | 98篇 |
2019年 | 150篇 |
2018年 | 198篇 |
2017年 | 143篇 |
2016年 | 213篇 |
2015年 | 217篇 |
2014年 | 264篇 |
2013年 | 353篇 |
2012年 | 544篇 |
2011年 | 535篇 |
2010年 | 304篇 |
2009年 | 266篇 |
2008年 | 501篇 |
2007年 | 541篇 |
2006年 | 487篇 |
2005年 | 527篇 |
2004年 | 500篇 |
2003年 | 473篇 |
2002年 | 476篇 |
2001年 | 429篇 |
2000年 | 403篇 |
1999年 | 355篇 |
1998年 | 119篇 |
1997年 | 101篇 |
1996年 | 83篇 |
1995年 | 75篇 |
1994年 | 69篇 |
1993年 | 70篇 |
1992年 | 208篇 |
1991年 | 182篇 |
1990年 | 167篇 |
1989年 | 169篇 |
1988年 | 141篇 |
1987年 | 152篇 |
1986年 | 120篇 |
1985年 | 132篇 |
1984年 | 89篇 |
1983年 | 75篇 |
1982年 | 32篇 |
1979年 | 60篇 |
1978年 | 34篇 |
1975年 | 34篇 |
1974年 | 34篇 |
1973年 | 33篇 |
1972年 | 39篇 |
1971年 | 45篇 |
1969年 | 37篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
51.
K Takeuchi K Matsubayashi S Kimura A Kawamoto T Ozawa K Shimada 《Nihon Ronen Igakkai zasshi. Japanese journal of geriatrics》1992,29(7-8):549-553
Lacunes on brain MRI, causal blood pressure, 24-hour ambulatory blood pressure and common carotid blood flow measured by the doppler method were studied in 31 elderly patients with Parkinson's disease (mean age 67.5 +/- 7.3 years). Nineteen patients with Parkinson's disease (61%) had at least one lacune. Patients with lacunes (P(+)) were significantly higher in age than patients without lacune (P(-)). The difference of casual blood pressure between patients in the two groups was not significant. On the other hand, the average of ambulatory blood pressure measurements during a 24-hour period was significantly higher in the P(+) group than in the P(-) group. The average of carotid blood flow was also significantly lower in the P(+) group than in the P(-) group, however, after adjustment for age, the difference between them became insignificant. In conclusion, the incidence of silent lacunes on brain MRI was fairly common in elderly patients with Parkinson's disease. A high average 24-hour ambulatory blood pressure was suggested to be one of the risk factors of lacunar stroke in elderly cases of Parkinson's disease. The concept of "combine type" in Parkinsonism was supposed to be suitable as well as in senile dementia of Alzheimer type. 相似文献
52.
Incidental brain lesions on magnetic resonance imaging and neurobehavioral functions in the apparently healthy elderly. 总被引:9,自引:0,他引:9
K Matsubayashi K Shimada A Kawamoto T Ozawa 《Stroke; a journal of cerebral circulation》1992,23(2):175-180
BACKGROUND AND PURPOSE: Controversies exist whether incidental neuroradiological brain lesions in the elderly are associated with depressed neuropsychological function. To address this important issue in a cross-sectional study, we related brain lesions on magnetic resonance imaging to a variety of cognitive and neurobehavioral function tests in an independent, normal elderly population. METHODS: We studied 73 independent asymptomatic elderly individuals (mean +/- SD age 70 +/- 6 years) to determine the relations between degree of brain atrophy, location and number of "lacunes," and grade of periventricular hyperintense lesions with a variety of cognitive and neurobehavioral function scores. RESULTS: We found that severity of neuroradiological changes increased while neuropsychological function scores declined with age. After adjustment for the effect of age, advanced periventricular hyperintensities, but not brain atrophy or patchy "lacunar" lesions, were associated with declines in all neuropsychological functions tested. CONCLUSION: We conclude that incidental advanced periventricular diffuse or patchy white matter changes may play a role in the development of cognitive and neurobehavioral impairments in apparently normal elderly persons. 相似文献
53.
Identification of receptors and Smad proteins involved in activin signalling in a human epidermal keratinocyte cell line 总被引:2,自引:0,他引:2
54.
Summary By using polyclonal and monoclonal antibodies against connectin (titin) which stain the A-I junctional area and the A-band domain (polyclonal anti-connectin and monoclonal 4C9) and the I-band domain (monoclonal SM1), the developmental relationship of this elastic protein with sarcomeric proteins, especially myosin and-actinin, was examined in embryonic chick cardiac myocytesin vitro under fluorescence microscopy. During premyofibril stages, I-Z-I proteins were detected first (-actinin dots and diffuse actin [phalloidin and anti-troponin C] staining), and later in these areas connectin and myosin dots appeared with nearly identical distribution. Somewhat later, phalloidin-positive nonstriated fibrils were observed in a straight course. They were always reactive with antibodies against a-actinin and troponin C, but unreactive or only weakly reactive with anticonnectin and anti-myosin. Initially,-actinin dots were aligned along these fibrils but did not form striations. As they aggregated to form Z-bands, connectin and myosin started to exhibit typical striations (doublets and A-bands, respectively). No difference in the staining pattern was observed with two kinds of monoclonal antibodies against different domains of connectin filaments (4C9 and SM1) at early phases. As myosin staining began to show clear A-bands, connectin epitopes became arranged in polarized positions. We conclude that primitive I-Z-I complexes appear prior to the assembly of connectin and myosin filaments and then connectin filaments, developing intimately and coordinately with myosin, become associated with the-actinin lines. Thus it appears that the putative elastic protein connectin plays some role in integrating myosin filaments with the preexisting I-Z-I brushes. The occasional absence of connectin and A-bands between two Z-bands, beyond both of which clear sarcomeres have been formed, indicates that connectin is not a preformed scaffold of myofibrils on which sarcomeric proteins accumulate. 相似文献
55.
Satoko Arai Yuka Shinohara Yasuyuki Kato Satoshi Hirano Atsuto Yoshizawa Masaaki Hojyo Nobuyuki Kobayashi Haruhito Sugiyama Koichiro Kudo 《Arerugī》2007,56(10):1293-1297
A 51-year-old man was admitted to our hospital with fever, dry cough and dyspnea. He had taken minocycline for 11 days because of urinary tract infection. Chest X-ray on admission showed diffuse reticular shadows in bilateral lung fields with bilateral pleural effusion. Cessation of minocycline led to spontaneous improvement of symptoms and radiographic findings. The lymphocyte stimulation test for minocycline with peripheral blood and pleural effusion were negative. After provocation test with minocycline, he developed fever and dry cough and bilateral ground glass opacity appeared on his chest X-ray. He was diagnosed as minocycline-induced pneumonitis and recovered rapidly following corticosteroid therapy. 相似文献
56.
Chakraborty S Garg P Ramamurthy T Thungapathra M Gautam JK Kumar C Maiti S Yamasaki S Shimada T Takeda Y Ghosh A Nair GB 《Journal of medical microbiology》2001,50(10):879-888
This study identified 17 matching serogroups of Vibrio cholerae belonging to serogroups other than O1 and O139 isolated from human cases and from the environment during a concurrent clinical and environmental study conducted in Calcutta, a cholera endemic area. Isolates within these matching serogroups were compared by various phenotypic and genotypic traits to determine if the environment was the source of the organisms associated with the disease. Clinical strains of V. cholerae were resistant to a greater number of drugs and exhibited multi-drug resistance compared with their environmental counterparts. Except for the presence of the genes for the El Tor haemolysin and the regulatory element ToxR in most of the strains of V. cholerae examined, non-O1, non-O139 V. cholerae strains lacked most of the other known virulence traits associated with toxigenic V. cholerae O1 or O139. Restriction fragment-length polymorphism of virulence-associated genes, ribotypes and DNA fingerprints of strains of matched serogroups showed considerable diversity, although some gene polymorphisms and ribotypes of a few strains of different serogroups were similar. It is concluded that despite sharing the same serogroup, environmental and clinical isolates were genetically heterogeneous and were of different lineages. 相似文献
57.
58.
Repair of infarcted myocardium mediated by transplanted bone marrow-derived CD34+ stem cells in a nonhuman primate model 总被引:6,自引:0,他引:6
Yoshioka T Ageyama N Shibata H Yasu T Misawa Y Takeuchi K Matsui K Yamamoto K Terao K Shimada K Ikeda U Ozawa K Hanazono Y 《Stem cells (Dayton, Ohio)》2005,23(3):355-364
Rodent and human clinical studies have shown that transplantation of bone marrow stem cells to the ischemic myocardium results in improved cardiac function. In this study, cynomolgus monkey acute myocardial infarction was generated by ligating the left anterior descending artery, and autologous CD34(+) cells were transplanted to the peri-ischemic zone. To track the in vivo fate of transplanted cells, CD34(+) cells were genetically marked with green fluorescent protein (GFP) using a lentivirus vector before transplantation (marking efficiency, 41% on average). The group receiving cells (n = 4) demonstrated improved regional blood flow and cardiac function compared with the saline-treated group (n =4) at 2 weeks after transplant. However, very few transplanted cell-derived, GFP-positive cells were found incorporated into the vascular structure, and GFP-positive cardiomyocytes were not detected in the repaired tissue. On the other hand, cultured CD34(+) cells were found to secrete vascular endothelial growth factor (VEGF), and the in vivo regional VEGF levels showed a significant increase after the transplantation. These results suggest that the improvement is not the result of generation of transplanted cell-derived endothelial cells or cardiomyocytes; and raise the possibility that angiogenic cytokines secreted from transplanted cells potentiate angiogenic activity of endogenous cells. 相似文献
59.
Yasuyuki Shibuya Hisashi Yasuda Masaki Tomatsuri Akira Mizoguchi Masatoshi Takeichi Keikichi Shimada Chizuka Ide 《Journal of neurocytology》1996,25(1):615-624
Summary The Ca2+-dependent intercellular adhesion molecule cadherin is known to be linked to the cytoskeleton by the protein catenin, an association of which appears to be important for the cell-adhesion function of cadherin. Catenin consists of three subtypes-, , and . In our previous study, N-cadherin was shown to be localized on the plasmalemma of normal and regenerating chick peripheral nerve. Thus, as N-catenin is a subtype of -catenin (which is specifically associated with N-cadherin), we investigated the immunolocalization of N-catenin in normal and regenerating chick sciatic nerve. In normal nerve, unmyelinated axons exhibited either intense or weak N-catenin immunoreactivity throughout the axoplasm, whereas myelinated axons were completely immunonegative. Regenerating axons, including those derived from parent myelinated axons, showed N-catenin immunoreactivity of variable intensities in growth cones and axon shafts. Schwann cells were invariably devoid of immunoreactivity. Thus N-catenin is not necessarily bound to the surface plasmalemma, but is distributed throughout the cytoplasm, suggesting that most N-catenin molecules are dissociated from N-cadherin. 相似文献
60.
H. Shimada K. Noda M. Mori N. Aoki M. Tajima K. Kato 《Virchows Archiv : an international journal of pathology》1994,424(5):569-572
Virions resembling papovavirus were demonstrated in glial cells in the brain of an aged patient without overt progressive multifocal leukoencephalopathy. The patient was not in a severely immunocompromised state. On histological examination, only a few tiny incomplete necrotic foci were found in the subcortical area. These foci were widely dispersed. Rare, swollen oligodendroglial cells and astrocytes in which papovavirus capsid protein (VP-1) was demonstrated immunohistochemically were present around the foci. The two typical types of virus particles i.e. 35 to 40 nm round particles and elongated particles, were observed in the nuclei of the swollen glial cells. The latter were in the minority. Distinct crystals were also found in the nuclei. The centre-to-centre distance of the particles in the crystals, about 40 nm, and the electron-opaque spots of the round-shaped virions and of the elongated particles, were indicative of structural subunits of papovavirus capsids. This case provides further evidence that papovavirus, possibly JC virus, may be reactivated in the brains of aged patients who are not in an immunocompromised state. 相似文献