全文获取类型
收费全文 | 10720篇 |
免费 | 538篇 |
国内免费 | 50篇 |
专业分类
耳鼻咽喉 | 100篇 |
儿科学 | 200篇 |
妇产科学 | 146篇 |
基础医学 | 1284篇 |
口腔科学 | 286篇 |
临床医学 | 745篇 |
内科学 | 2505篇 |
皮肤病学 | 199篇 |
神经病学 | 663篇 |
特种医学 | 632篇 |
外科学 | 2183篇 |
综合类 | 34篇 |
一般理论 | 1篇 |
预防医学 | 246篇 |
眼科学 | 101篇 |
药学 | 604篇 |
中国医学 | 18篇 |
肿瘤学 | 1361篇 |
出版年
2023年 | 78篇 |
2022年 | 129篇 |
2021年 | 267篇 |
2020年 | 156篇 |
2019年 | 210篇 |
2018年 | 233篇 |
2017年 | 208篇 |
2016年 | 243篇 |
2015年 | 241篇 |
2014年 | 317篇 |
2013年 | 311篇 |
2012年 | 553篇 |
2011年 | 564篇 |
2010年 | 316篇 |
2009年 | 256篇 |
2008年 | 490篇 |
2007年 | 542篇 |
2006年 | 488篇 |
2005年 | 538篇 |
2004年 | 488篇 |
2003年 | 463篇 |
2002年 | 462篇 |
2001年 | 328篇 |
2000年 | 324篇 |
1999年 | 330篇 |
1998年 | 143篇 |
1997年 | 107篇 |
1996年 | 117篇 |
1995年 | 68篇 |
1994年 | 80篇 |
1993年 | 61篇 |
1992年 | 216篇 |
1991年 | 181篇 |
1990年 | 163篇 |
1989年 | 153篇 |
1988年 | 181篇 |
1987年 | 155篇 |
1986年 | 121篇 |
1985年 | 135篇 |
1984年 | 93篇 |
1983年 | 85篇 |
1979年 | 71篇 |
1978年 | 57篇 |
1977年 | 44篇 |
1976年 | 42篇 |
1974年 | 45篇 |
1973年 | 44篇 |
1972年 | 51篇 |
1971年 | 39篇 |
1969年 | 45篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
Chronic active Epstein-Barr virus (EBV) infection has been recognized as clonal non-neoplastic lymphoproliferative diseases. However, some reports of cases with a multiphenotypic expansion of EBV-infected lymphocytes give rise to questions of how EBV infects multiphenotypic lymphocytes and whether chronic active EBV infection is a truly monoclonal lymphoproliferative disease. We report two patients with chronic active EBV infection who showed expansion of multiphenotypic EBV-infected lymphocytes. EBV DNA was detected in CD4+ and CD8+ T cells and in B cells from pleural fluid of one patient and in T and B cells from a cervical lymph node of the other patient by polymerase chain reaction (PCR). Although real-time PCR showed that there were equally high loads of EBV genomes in CD4+ and CD8+ T cells from the pleural fluid, Southern blot hybridization with terminal repeats of the EBV genome showed a single band of the same molecular weight in three tissue samples from the patient. The results indicated biphenotypic expansions of CD4+ and CD8+ T cells infected with the same clone of EBV. Furthermore, bisulfite PCR analysis showed hypermethylated status in the Cp region in the two patients regardless of their cell populations. There has been a discrepancy between clonality and expansion of multiphenotypic EBV-infected lymphocytes. We speculate that lymphoid progenitor cells that have not differentiated into T and B cell progenitors are infected with EBV, resulting in clonal expansion of EBV-infected multiphenotypic cells. 相似文献
82.
Postsynaptic potentials (PSPs) with long latencies were evoked in cat hindlimb motoneurons by stimulation of the distal stump of a cut ventral root. Measurements of their latency and the threshold in the responsible afferent fibers showed that they were produced mainly by the activity of the unmyelinated fibers in the ventral root that enter the spinal cord through the dorsal root. Patterns of PSPs evoked in flexor and extensor motoneurons by ventral root stimulation were similar to those observed in the flexion reflex. 相似文献
83.
S. Lindstrom A. Endo S. Sugita M. Pecoraro Y. Hiromoto M. Kamada T. Takahashi K. Nerome 《Archives of virology》1998,143(8):1585-1598
Summary. Matrix (M) and nonstructural (NS) genes of thirteen equine H3N8 and H7N7 influenza viruses were sequenced and analyzed from
an evolutionary point of view. The M and NS genes of H3N8 viruses isolated between 1989 and 1993 evolved into two minor branch
clusters, including isolates from Europe and the American continent, respectively. It was noteworthy to reveal that the nucleotide
sequences of the M and NS genes of an earlier American strain showed highest homology to those of recent European viruses.
“Frozen evolution” was observed in the M and NS genes of A/eq/LaPlata/1/88. It was also evident that the NS gene of an H7N7
virus from 1977 was very similar to that of a 1979-H3N 8 virus, while the M gene was closest phylogenetically to that of the
earliest H7N7 virus isolated in 1956. Furthermore, the M2 protein of A/eq/Newmarket/1/77 virus contained a carboxyl terminal
deletion of three amino acids. The evolutionary rates of the M and NS genes of H3N8 equine influenza viruses were estimated
to be 5.4 × 10−4 and 5.1 × 10−4 substitutions per site per year, respectively, which were slower than those of human viruses.
Received November 21, 1997 Accepted March 9, 1998 相似文献
84.
85.
Endo S Inoue Y Fujino Y Yamada Y Sato N Wakabayashi G Sakamoto T Ishikura H Tanaka T Inada K Sato S 《Research communications in molecular pathology and pharmacology》2000,108(3-4):179-186
The FasL-Fas system is an apoptosis induction system and plays an important role in homeostasis and biophylaxis. The present study was conducted to investigate soluble Fas (sFas), soluble Fas ligand (sFasL), and tumor necrosis factor alpha (TNF-alpha) in patients with acute pancreatitis. As acute pancreatitis became severe, the levels of sFas in the serum increased significantly, while those of sFasL decreased significantly. A significant inverse correlation was observed between the serum levels of sFas and those of sFasL. Also, a significant positive correlation was observed between the levels of TNF-alpha and sFas. A greater increase in serum sFas and decrease in serum sFasL levels was observed in patients with complicating multiple organ dysfunction syndrome (MODS) than in those without it. The results of the study suggest that the pathological aggravation of acute pancreatitis could be related to changes in the Fas-FasL system. 相似文献
86.
Terada T Matsunaga Y Maeta H Endo K Horie S Ohta T 《Virchows Archiv : an international journal of pathology》1999,435(6):606-611
We report an autopsy case of mixed ductal-endocrine carcinoma of the pancreas presenting as gastrinoma with Zollinger-Ellison
syndrome. A 38-year-old Japanese male was found to have Zollinger-Ellison syndrome and pancreatic gastrinoma, and gastrectomy
and resection of the pancreatic tumor were performed. However, hypergastrinemia persisted, and the patient died of disseminated
carcinomatosis at 62 years of age, 24 years after the onset of Zollinger-Ellison syndrome. At autopsy, the main tumor was
present in the residual pancreas, and metastases were noted in many organs. In the pancreas and other organs, ductal and endocrine
carcinoma areas were mixed and there was a gradual transition between the two. No acinar differentiation was noted. The ductal
elements were positive for mucins and carcinoembryonic antigen but negative for neuroendocrine markers, while endocrine elements
were positive for chromogranin A and synaptophysin and to a lesser extent for gastrin, but negative for mucins and carcinoembryonic
antigen. The ductal elements comprised about 30% of the tumor cells, and endocrine elements 70%. According to the revised
World Health Organization classification, our case was diagnosed as mixed ductal-endocrine carcinoma. Our case is rare because
the tumor manifested as gastrinoma with Zollinger-Ellison syndrome and the patient survived for 24 years. To the best of our
knowledge, no such case has been reported. Our case suggests that pancreatic endocrine tumors may evolve into mixed ductal-endocrine
carcinomas.
Received: 14 April 1999 / Accepted: 7 July 1999 相似文献
87.
Naoya Nakamura Naoyoshi Mori Koichi Ohshima Tetsuo Kuze Yuko Hashimoto Yoshikazu Sasaki Asumi Shirakawa Michiko Sato Masafumi Abe 《Diagnostic molecular pathology》2002,11(2):83-89
We examined nucleotide sequences of Epstein-Barr virus (EBV)-positive Hodgkin/Reed-Sternberg (HRS)-like B cells in a case of diffuse large B-cell lymphoma (DLBCL) and a case of adult T-cell lymphoma (ATL) for single-cell polymerase chain reaction of the immunoglobulin heavy-chain gene variable region (VH gene). HRS-like B cells were scattered in the area irrelevant to the lymphoma infiltrates of DLBCL and in the lymphoma area of ATL. HRS-like B cells were positive for CD20 and CD30 but negative for CD15. EBV presented in HRS-like B cells in both cases but not in any lymphoma cells. VH genes of five HRS-like B cells analyzed in DLBCL were polyclonal and showed in-frame sequences with 0% to 2.8% somatic mutation frequency. In an ATL, VH genes of five HRS-like B cells analyzed were polyclonal and somatically mutated. Four cells carried in-frame rearrangements with 3.5% to 17.7% mutation frequency. One of the VH genes has a one-codon deletion. From the fifth cell, an out-of-frame rearrangement with an insertion and a deletion was obtained. Thus, we showed polyclonal EBV-positive HRS-like B cells in both DLBCL and ATL and that whereas EBV-positive, HRS-like B cells in DLBCL exhibited unmutated and mutated VH gene, those in ATL were found to have a somatically mutated VH gene with/without deletions and/or insertions. The HRS-like B cells may appear because of active EBV infection in a patient who is immunosuppressed from the primary lymphoma. 相似文献
88.
89.
To evaluate the pathogenetic roles of immune complexes and alveolar hyaline membrane in idiopathic interstitial pneumonia (IIP), immunohistological and ultrastructural studies of the kidney and lung were performed in 23 cases of IIP, 19 cases of autoimmune diseases, 17 cases of interstitial pneumonia other than IIP, and 11 cases of bronchopneumonia as a control group. None of the cases of IIP or interstitial pneumonia other than IIP showed immune complexes in the alveolar and glomerular capillary walls. On the other hand, one case of SLE was positive for IgG and components of complement along the alveolar and glomerular capillary walls. The alveolar hyaline membrane in the present cases revealed immunoglobulins as well as components of complement, which were poorly soluble in chaotropic solution or acidic buffer. These results indicate that circulating immune complexes play a minor role in the pathogenesis of IIP and other types of interstitial pneumonia, and that there is no relationship between immune complex deposition in alveoli and the alveolar hyaline membrane. It is necessary to further investigate factors other than immune complexes involved in alveolar tissue damage and to clarify the significance of the hyaline membrane in the processes occurring from acute changes to pulmonary fibrosis in IIP. 相似文献