全文获取类型
收费全文 | 236722篇 |
免费 | 21479篇 |
国内免费 | 11487篇 |
专业分类
耳鼻咽喉 | 3483篇 |
儿科学 | 4115篇 |
妇产科学 | 3206篇 |
基础医学 | 38346篇 |
口腔科学 | 6381篇 |
临床医学 | 18347篇 |
内科学 | 33183篇 |
皮肤病学 | 4799篇 |
神经病学 | 10979篇 |
特种医学 | 7214篇 |
外国民族医学 | 217篇 |
外科学 | 23613篇 |
综合类 | 38555篇 |
现状与发展 | 64篇 |
预防医学 | 6289篇 |
眼科学 | 3769篇 |
药学 | 16375篇 |
42篇 | |
中国医学 | 5988篇 |
肿瘤学 | 44723篇 |
出版年
2024年 | 483篇 |
2023年 | 3309篇 |
2022年 | 6122篇 |
2021年 | 8459篇 |
2020年 | 7423篇 |
2019年 | 7149篇 |
2018年 | 7227篇 |
2017年 | 7893篇 |
2016年 | 8502篇 |
2015年 | 9740篇 |
2014年 | 14221篇 |
2013年 | 14770篇 |
2012年 | 13451篇 |
2011年 | 15029篇 |
2010年 | 12425篇 |
2009年 | 11980篇 |
2008年 | 12600篇 |
2007年 | 13115篇 |
2006年 | 12076篇 |
2005年 | 10931篇 |
2004年 | 9389篇 |
2003年 | 8154篇 |
2002年 | 6770篇 |
2001年 | 6088篇 |
2000年 | 5071篇 |
1999年 | 4400篇 |
1998年 | 4173篇 |
1997年 | 3750篇 |
1996年 | 3394篇 |
1995年 | 2948篇 |
1994年 | 2608篇 |
1993年 | 2088篇 |
1992年 | 1738篇 |
1991年 | 1604篇 |
1990年 | 1271篇 |
1989年 | 1169篇 |
1988年 | 1090篇 |
1987年 | 889篇 |
1986年 | 814篇 |
1985年 | 1041篇 |
1984年 | 889篇 |
1983年 | 636篇 |
1982年 | 672篇 |
1981年 | 557篇 |
1980年 | 469篇 |
1979年 | 345篇 |
1978年 | 245篇 |
1977年 | 177篇 |
1976年 | 141篇 |
1975年 | 51篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
51.
In human Y-79 retinoblastoma cells corticotropin-releasing hormone (CRH) produces a marked and rapid increase of adenylate cyclase activity. The concentration of the peptide producing half-maximal stimulation is 60 nM. The effect of CRH is significantly antagonized by the specific CRH receptor antagonist alpha-helical CHR 9-41 and is mimicked by sauvagine and urotensin I, two peptides displaying sequence homology with CRH. These results demonstrate the presence of functional CRH receptors in human Y-79 retinoblastoma cells and suggest that this cell line may be a suitable model in which to study the action of CRH on human retinal cell function. 相似文献
52.
A retrospective analysis of treatment for endometrial carcinoma is reported here. From 1987 to 1989, 138 patients were referred to the oncology department following total abdominal hysterectomy and bilateral salpingo-oophorectomy for endometrial cancer. Forty-seven patients were not prescribed postoperative radiotherapy; 31 had Stage I well differentiated adenocarcinoma with minimal myometrial invasion, while the remaining 16 patients were considered unfit for postoperative radiotherapy. There were no instances of local relapse amongst the 31 patients with minimal myometrial invasion.The remaining 91 patients all received external beam irradiation to the pelvis and, according to the preference of the individual therapist, 51 were prescribed additional intracavitary vault caesium-137. Patients receiving postoperative radiotherapy were analysed according to whether or not they received additional intracavitary vault caesium. The two groups were also analysed for incidence of vaginal vault recurrence and treatment related morbidity.In the group receiving additional intracavitary treatment more patients had Stage II or III disease (P<0.05), and had greater depth of myometrial invasion (P<0.05). Vaginal vault recurrence was not observed in patients receiving intracavitary therapy in addition to external beam therapy. Four patients (10%) receiving external beam therapy alone developed vaginal vault recurrence.The incidence of Kottmeier-Perez grade 2 or 3 bowel toxicity following treatment was significantly higher in those patients receiving combined treatment (18% vs. 2.5%; P<0.03). There was also a higher incidence of vaginal stenosis in the group receiving both external beam and intracavitary therapy (21% vs. 3%; P<0.05). There was only one instance of grade 2 bladder toxicity in the external beam and intracavitary treatment group and none in the external beam therapy alone group.In conclusion, postoperative radiotherapy for Stages I-III endometrial carcinoma was carried out in a non-randomized manner by two regimens; either external beam therapy alone or external beam therapy with additional intracavitary vaginal caesium. The combined therapy gave significantly better local control but resulted in significantly more late bowel and vaginal morbidity. 相似文献
53.
P. Andersson K. LeBlanc B-. Eriksson J. Samuelsson 《European journal of haematology》1997,59(5):310-317
Abstract: Polycythaemia vera (PV) is a myeloproliferative disorder characterized by haematopoietic progenitor cells being hypersensitive to cytokines such as erythropoietin, interleukin-3, stem cell factor and insulin-like growth factor 1, which results in an increased production of mature blood cells. The pathogenetic cellular mechanism(s) behind this hypersensitivity to cytokines is unknown, but the number of cytokine receptors and the interaction between ligand and receptor are normal in PV. Interest has therefore focused on post-receptor mechanism(s). Haematopoietic cell phosphatase (HCP) is an intracellular tyrosine phosphatase that has been demonstrated to regulate proliferative signals negatively induced by the cytokines mentioned above. Moreover, motheaten mice that genetically lack HCP have an increased amount of erythroid progenitors that are hypersensitive to Epo, and patients with familial polycythaemia have been shown to exhibit a mutation of the Epo receptor gene that includes the docking site for HCP. We therefore studied mRNA expression of HCP in pure populations of CD34+ cells, granulocytes, platelets and lymphocytes from patients with PV, chronic myeloid leukaemia (CML) or essential thrombocythemia (ET), as well as healthy controls. Using a polymerase chain reaction analysis employing specific primers for HCP, we failed to detect any abnormalities of HCP expression in PV in any of the cell populations that were examined. Moreover, HCP mRNA expression was similar in ET and CML compared to controls. Finally, Western blot analysis revealed a normal HCP protein content in PV granulocytes and platelets. We therefore conclude that neither an impaired expression of the HCP gene nor a defect in HCP protein synthesis is present in PV, and does not seem to play a role in the aetiology of this disorder. 相似文献
54.
Ken Igawa Ryuji Maruyama Ichiro Katayama Kiyoshi Nishioka 《The Journal of dermatology》1997,24(5):328-331
A 72-year-old fisherman who was positive for the HCV antibody developed an annular, erythematous, infiltrated lesions on sun-exposed areas. The lesions were diagnosed as annular elastolytic giant cell granuloma both clinically and histologically. Topical corticosteroid and cryotherapy with liquid nitrogen for several months failed to improve the lesions. We then started dapsone, a known anti-oxidant, at 50 mg/day. A month later, the margins of the erythematous lesions faded, and the infiltration gradually decreased. No recurrence has been observed for one year after the start of the therapy. Anti-oxidative therapy appears to be effective for annular elastolytic giant cell granuloma and could be an alternate therapy for refractory granulomatous disease. 相似文献
55.
Reyna O. Calderon B. Maggio T. J. Neuberger G. H. Devries 《Journal of neuroscience research》1993,34(2):206-218
The axolemma membrane forms a stable and reproducible monomolecular layer at the air-aqueous interface. The major lipids and proteins are present in this monolayer in molar ratios similar to the original membrane. Acetylcholinesterase and Na-K-ATPase activities are preserved in the monolayer to levels of 64% and 25%, respectively. The total lipid fraction forms a homogeneously mixed phase. The presence of proteins in the monolayer introduces surface inhomogeneties. Among other features, this is revealed by the presence of two values of lateral pressure at which the monolayer shows partial or total collapse: a broad partial collapse at surface pressures between 13 to 30 mN/m and a sharp collapse point at 46 mN/m. The average molecular areas, the broad collapse point, and the variation of the surface potential per molecule suggest the relocation of protein components at surface pressures between 13 to 30 mN/m. The behavior is consistent with the extrusion and exposure of proteins toward the aqueous medium that depends on the lateral pressure. Schwann cells grown on coverslips coated with axolemma monolayers at 13 mN/m (beginning of the broad collapse) and 34 mN/m (above the broad collapse) recognize the difference in the surface organization of axolemma caused by the lateral pressure which affects their proliferation, morphology, and spatial pattern of organization. Our results show for the first time that response of Schwann cells depends on the intermolecular organization of the axolemma surface with which they interact. These results suggest that the local expression of putative surface molecules of axolemma that may mediate membrane recognition and the signalling of morphological and proliferative changes can be modulated by long range supramolecular properties. © 1993 Wiley-Liss, Inc. 相似文献
56.
一个RET原癌基因Met918Thr突变的多发性内分泌腺瘤病Ⅱb家系报道 总被引:1,自引:0,他引:1
目的 检测一个多发性内分泌腺瘤病(MEN)Ⅱb家系的RET原癌基因突变。方法 提取患者及其父母的外周血基因组DNA,对RET原癌基因第16外显子进行聚合酶链反应(PCR),将PCR扩增产物进行直接基因测序和限制性内切酶分析。结果 检测到患者RET原癌基因第16外显子918密码子存在ATG(Met)/ACG(Thr)点突变,而在患者父母中未检测到该突变。结论 通过对MENⅡb患者及其父母的基因筛查发现,该患者点突变是杂合子错义突变。该疾病的诊断达到了基因水平。 相似文献
57.
58.
T. Eiwegger N. Rigby L. Mondoulet H. Bernard M.-T. Krauth A. Boehm E. Dehlink P. Valent J. M. Wal E. N. C. Mills Z. Szépfalusi 《Clinical and experimental allergy》2006,36(10):1281-1288
BACKGROUND: The process of gastro-duodenal digestion may play a role in determining the allergenic properties of food proteins. The sensitizing and allergenic potential of digestion products of highly degraded allergens, such as the major peanut allergen Ara h 1, is currently under debate. We evaluated the effect of in vitro gastro-duodenal digestion of Ara h 1 on T cell reactivity and basophil histamine release. METHODS: An in vitro model of gastro-duodenal digestion was used to investigate changes in the allergenic properties of Ara h 1 using in vitro assays monitoring T cell reactivity (proliferation, cytokine production) and histamine release of basophils from peanut allergic individuals. The digestion process was monitored using an SDS-PAGE gel. RESULTS: In vitro gastric digestion led to rapid degradation of Ara h 1 into small fragments M(r) L5600. Gastric digestion did not affect the ability of Ara h 1 to stimulate cellular proliferation. Gastro-duodenal digestion significantly reduced its ability to stimulate clonal expansion (P<0,05; Wilxocon's signed rank test). The Th-2 type cytokine polarization of T cells from peanut allergic donors (IFN-gamma/IL-13 ratio and IFN-gamma/IL-4 ratio of CFSE(low) CD4(+) T cells) remained unchanged regardless of the level of digestion. Histamine release of basophils from peanut allergic individuals was induced to the same extent by native Ara h 1 and its digestion products. CONCLUSION: Gastro-duodenal digestion fragments of Ara h 1 retain T cell stimulatory and IgE-binding and cross-linking properties of the intact protein. 相似文献
59.
60.
Expression of p27 and p53: comparative analysis of uterine carcinosarcoma and endometrial carcinoma 总被引:1,自引:0,他引:1
A. Abargel I. Avinoach† V. Kravtsov† M. Boaz‡ M. Glezerman‡ & J. Menczer‡ 《International journal of gynecological cancer》2004,14(2):354-359
The aim of the study was to assess both p27 and p53 expression in the stromal and epithelial component of carcinosarcoma and to assess if their expression in the latter is different than in endometrial carcinoma. Immunohistochemical staining for p27 and p53 was performed on paraffin-embedded tissue blocks of 18 uterine specimens with carcinosarcoma and their expression assessed. Their expression in the epithelial element was also compared to that in 35 paraffin-embedded tissue blocks of endometrial endometrioid carcinoma. Reduced p27 expression was observed in a similarly high proportion of the stromal (77.8%) as well as of the epithelial component (66.7%) of carcinosarcoma. Although statistically not significant, the proportion of reduced p27 expression in endometrial carcinoma (85.7%) was higher than in the epithelial element of carcinosarcoma. The percentage of p53 overexpression in both elements of carcinosarcomas and in endometrial carcinomas was low and also similar (27.8 and 20.0%, respectively). Our results indicate that reduced p27 expression is common and p53 overexpression is infrequent in carcinosarcoma. Their similar rates of expression in the stromal and epithelial elements of the tumor support the contention of a monoclonal origin of carcinosarcoma. Unexpectedly, reduced p27 expression is more common in endometrial carcinoma than in the epithelial element of carcinosarcoma, in spite of the less favorable prognosticators and outcome in the latter. Further studies of p27 expression in carcinosarcoma are indicated to establish its clinical value in this aggressive malignancy. 相似文献