全文获取类型
收费全文 | 10798篇 |
免费 | 681篇 |
国内免费 | 59篇 |
专业分类
耳鼻咽喉 | 92篇 |
儿科学 | 249篇 |
妇产科学 | 261篇 |
基础医学 | 1529篇 |
口腔科学 | 272篇 |
临床医学 | 992篇 |
内科学 | 2696篇 |
皮肤病学 | 258篇 |
神经病学 | 1160篇 |
特种医学 | 260篇 |
外科学 | 1231篇 |
综合类 | 40篇 |
一般理论 | 4篇 |
预防医学 | 774篇 |
眼科学 | 190篇 |
药学 | 700篇 |
中国医学 | 34篇 |
肿瘤学 | 796篇 |
出版年
2024年 | 12篇 |
2023年 | 98篇 |
2022年 | 182篇 |
2021年 | 297篇 |
2020年 | 182篇 |
2019年 | 271篇 |
2018年 | 316篇 |
2017年 | 262篇 |
2016年 | 292篇 |
2015年 | 317篇 |
2014年 | 404篇 |
2013年 | 537篇 |
2012年 | 829篇 |
2011年 | 863篇 |
2010年 | 455篇 |
2009年 | 423篇 |
2008年 | 700篇 |
2007年 | 725篇 |
2006年 | 652篇 |
2005年 | 706篇 |
2004年 | 623篇 |
2003年 | 579篇 |
2002年 | 525篇 |
2001年 | 99篇 |
2000年 | 86篇 |
1999年 | 109篇 |
1998年 | 74篇 |
1997年 | 74篇 |
1996年 | 64篇 |
1995年 | 61篇 |
1994年 | 56篇 |
1993年 | 43篇 |
1992年 | 60篇 |
1991年 | 60篇 |
1990年 | 52篇 |
1989年 | 27篇 |
1988年 | 33篇 |
1987年 | 37篇 |
1986年 | 26篇 |
1985年 | 20篇 |
1984年 | 41篇 |
1983年 | 28篇 |
1982年 | 27篇 |
1981年 | 20篇 |
1980年 | 14篇 |
1979年 | 15篇 |
1977年 | 14篇 |
1976年 | 10篇 |
1975年 | 13篇 |
1974年 | 10篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
Okamoto T Hashimoto M Samejima H Mori A Wakabayashi M Takeda A Nakamura H Naruse H Bouike Y Araki N 《Immunopharmacology and immunotoxicology》2004,26(4):645-652
Immediate hemolytic transfusion reactions (IHTR) occurred in the course of delayed hemolytic transfusion reactions (DHTR). An 84-year-old man had received a blood transfusion 20 years ago. Progressive anemia developed, because of continuous bleeding from a bladder tumor. He was transfused with concentrated red blood cells (CRC) which were Rh-E antigen negative, because he had anti-E antibodies (day 0). He received CRC on day 3, and underwent resection of bladder tumor on day 6. Although crossmatch-compatible CRCs were prepared for the operation, those were not required and were kept in a refrigerator in the ward. On day 9, when a CRC kept in the ward was transfused, he suddenly had a IHTR. In order to analyze a mechanism of IHTR, the anti-Jk(b) and anti-Di(b) antibodies, anti-HLA antibodies and the concentrations of inflammatory cytokines were measured in serum samples. The anti-Jk(b) and anti-Di(b) antibodies increased prior to IHTR experienced on day 9. The concentrations of IL-6 and IL-1beta increased from day 2, while the concentration of IL-8 increased from day 7. The anti-HLA class I antibody could be detected 2 days before IHTR. Thus, the anti-Jk(b) and anti-Di(b) antibodies induced the production of inflammatory cytokines and symptoms of DHTR and IHTR. The anti-HLA class I antibody could be produced in spite of using the filer for removing leukocytes, and may take part in the induction of IHTR. Further, blood products should be transfused soon after completing a crossmatch test in patients with anti-RBC alloantibodies. 相似文献
62.
K-ras gene mutational analysis supports a monoclonal origin of biphasic pleomorphic carcinoma of the lung. 总被引:2,自引:0,他引:2
Giuseppe Pelosi Aldo Scarpa Michela Manzotti Giulia Veronesi Lorenzo Spaggiari Filippo Fraggetta Oscar Nappi Elvira Benini Felice Pasini Davide Antonello Antonio Iannucci Patrick Maisonneuve Giuseppe Viale 《Modern pathology》2004,17(5):538-546
We investigated 27 pleomorphic carcinomas of the lung for exon 1 K-ras gene mutations using polymerase chain reaction-single-strand conformation polymophism analysis and direct sequencing. All pleomorphic carcinomas were biphasic, that is, composed of an adeno-, squamous- or large-cell-carcinomatous component associated with a spindle- and/or giant-cell component. Of 27 cases, six (22%) showed K-ras codon 12 mutations, which is a figure higher than that previously reported on in pure sarcoma-like pleomorphic carcinomas. Five tumors displayed the same mutation in both the epithelial and the sarcomatoid components, whereas in one tumor the mutation was restricted to the epithelial component. All mutations occurred in smokers, and were transversions, including GGT (glycine) to TGT (cysteine) change in two cases, to GCT (alanine) in two and to GTT (valine) in two. No significant relationships were found between the occurrence and type of mutations and patients' survival or any other clinicopathological variable, suggesting that K-ras mutations are early events in the development of these tumors. Our results indicate that most, though not all, biphasic pleomorphic carcinomas of the lung are monoclonal in origin, and that cigarette smoking may have a causative role in the development of K-ras alterations in these tumors, as all mutations are transversions. 相似文献
63.
BACKGROUND: Rat basophilic leukemia (RBL-2H3) cells are well characterized in terms of morphological and biochemical changes upon activation, and have been extensively used as a model system for studying the mechanisms of the immediate hypersensitivity reaction. To investigate whether overexpression of heat shock/stress proteins (HSP) is involved in the mast cell-dependent reactivity, we examined the adaptive responses of RBL-2H3 cells to classical stress conditions such as heat shock or oxidative injury produced by an aqueous extract of tobacco smoke. METHODS: HSP were determined by flow cytometry and immunocytochemistry. Degranulation was confirmed as the release of beta-hexosaminidase, determined spectrophotometrically, and by electron microscopy experiments. RESULTS: We found that RBL-2H3 cells respond to heat shock or oxidative injury by the synthesis of both the inducible 72 kDa HSP (Hsp70), and the oxidation-specific 32 kDa heme oxygenase (HO)-1. Heat shock induced mainly Hsp70 in a cell growth-dependent manner, whereas oxidative stress induced mainly HO-1 in a cell growth-independent manner. However, heat shock or oxidative stress had no significant effects on degranulation. CONCLUSION: Stress-mediated synthesis of HSP was not associated with RBL-2H3 degranulation and likewise, degranulation did not induce HSP. 相似文献
64.
Mancuso M Conforti FL Rocchi A Tessitore A Muglia M Tedeschi G Panza D Monsurrò M Sola P Mandrioli J Choub A DelCorona A Manca ML Mazzei R Sprovieri T Filosto M Salviati A Valentino P Bono F Caracciolo M Simone IL La Bella V Majorana G Siciliano G Murri L Quattrone A 《Neuroscience letters》2004,371(2-3):158-162
Mitochondrial impairment has been implicated in the pathogenesis of the amyotrophic lateral sclerosis (ALS). Furthermore, mitochondrial-specific polymorphisms were previously related to other neurodegenerative diseases, such as Parkinson, Friedreich and Alzheimer disease. To investigate if specific genetic polymorphisms within the mitochondrial genome (mtDNA) could act as susceptibility factors and contribute to the clinical expression of sporadic ALS (sALS), we have genotyped predefined European mtDNA haplogroups in 222 Italian patients with sALS and 151 matched controls. Individuals classified as haplogroup I demonstrated a significant decrease in risk of ALS versus individuals carrying the most common haplogroup, H (odds ratio 0.08, 95% confidence interval 0.04-0.4, p < 0.01). Further stratification of the dataset by sex, age and site of onset of disease and survival failed to reach significance for association. Our study provides evidence of the contribution of mitochondrial variation to the risk of ALS development in Caucasians. Further it may help elucidate the mechanism of the mitochondrial dysfunction detectable in ALS, and may be of relevance in development of strategies for the treatment of this disease. 相似文献
65.
Francesca Grassi Aldo Giovannelli Sergio Fucile Elisabetta Mattei Fabrizio Eusebi 《Pflügers Archiv : European journal of physiology》1993,425(1-2):117-125
The cholinergic responses of the human tumour cell line TE671/RD were examined using digital Ca2+ imaging fluorescence microscopy and patch-clamp measurements. In response to stimulation of the muscarinic acetylcholine (ACh) receptor (mAChR), the intracellular concentration of Ca2+ ([Ca2+]i) rose about two-fold, in parallel with inositol 1,4,5-trisphosphate accumulation, measured by chromatographic techniques. By contrast, there was no increment of [Ca2+]i upon stimulation of the nicotinic ACh receptor (nAChR), nor after caffeine application. Electrophysiological experiments showed that TE671/RD cells lack functional voltage-activated Ca2+ channels. The stimulation of the nAChR induced transient whole-cell currents (I
ACh). Little or no current was detected in isotonic extracellular Ca2+, with Cs+ in the patch pipette. Cell pretreatment with muscarine reduced I
ACh by about 20%, without consistent modifications of current kinetics. Muscarine applied to the extra-patch membrane under the cell-attached configuration had no obvious effect on ACh-evoked unitary events. In conclusion, in human TE671/ RD cells, muscarinic stimulation increases [Ca2+]i, while nicotinic stimulation does not. In addition, the nAChR exhibits peculiar ion permeability properties and is not functionally regulated by the breakdown of phosphoinositides. 相似文献
66.
67.
Dpc4 is expressed in virtually all primary and metastatic pancreatic endocrine carcinomas 总被引:2,自引:0,他引:2
Scarpa A Orlandini S Moore PS Lemoine NR Beghelli S Baron A Falconi M Zamboni G 《Virchows Archiv : an international journal of pathology》2002,440(2):155-159
DPC4/Smad4 is inactivated in about 50% of pancreatic ductal cancers. It has been recently reported that this gene is also inactivated in neoplasms arising from pancreatic islet cells, a phenomenon suggested to be related to similar progressions of malignancy found in common ductal cancers. To evaluate this possibility, we analysed 20 metastases of pancreatic endocrine carcinomas and their corresponding primary lesion for inactivation of DPC4 using immunohistochemical staining. In fact, immunohistochemical labelling has been shown to correlate with DPC4 gene status with high sensitivity and specificity. The cancers included 18 nonfunctioning tumours, one gastrinoma and one ViPoma all with liver, nodal and/or adrenal metastases. Seventeen were well-differentiated and three poorly differentiated endocrine carcinomas. Dpc4 expression was absent in only one primary well-differentiated endocrine cancer and its liver metastasis, while all the remaining 19 primary tumours and their metastases stained positive for the protein. All positively staining cases showed diffuse cytoplasmic and nuclear staining in virtually all neoplastic cells. Our data suggest that DPC4 is only rarely involved in pancreatic endocrine tumourigenesis and give further weight to the hypothesis that tumours arising from pancreatic exocrine and endocrine epithelia are genetically distinct. 相似文献
68.
69.
Calorini L Mannini A Bianchini F Mugnai G Balzi M Becciolini A Ruggieri S 《Clinical & experimental metastasis》1999,17(10):889-895
A previous study by our laboratory showed that the peritoneal murine Corynebacterium parvum-elicited macrophages released into their growth medium an activity which enhanced the ability of B16-F10 melanoma cells to
form experimental metastases in the lung of syngeneic mice. In the present study, we used a clone of B16-F10 line (F10-M3
cells) to investigate whether the increase in lung-colonizing potential due to the pro-clonogenic activity released by C. parvum-elicited macrophages was associated with biological properties characteristic of a metastatic phenotype. We have found that
the pulmonary retention, growth rate in lung parenchyma, invasiveness through Matrigel, adhesiveness to IL-1-activated endothelium
and MHC class I expression were increased in F10-M3 cells stimulated by the macrophage pro-clonogenic activity. By using an
in vitro experimental protocol, the enhancement of lung-colonizing potential in the stimulated melanoma cells turned out to be a transient
phenomenon as was the increase of invasiveness through Matrigel and the higher expression of MHC class I antigens. In conclusion,
the melanoma cells stimulated by the pro-clonogenic activity released by C. parvum-elicited macrophages showed changes in biological parameters which are relevant to metastatic diffusion. These changes appeared
as a temporary phenomenon which sustains the view that the metastatic phenotype represents a transient biological character
influenced by host factors.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
70.