全文获取类型
收费全文 | 82614篇 |
免费 | 7977篇 |
国内免费 | 5736篇 |
专业分类
耳鼻咽喉 | 735篇 |
儿科学 | 792篇 |
妇产科学 | 708篇 |
基础医学 | 9039篇 |
口腔科学 | 1877篇 |
临床医学 | 11087篇 |
内科学 | 11085篇 |
皮肤病学 | 690篇 |
神经病学 | 3823篇 |
特种医学 | 3043篇 |
外国民族医学 | 48篇 |
外科学 | 7797篇 |
综合类 | 16573篇 |
现状与发展 | 25篇 |
一般理论 | 2篇 |
预防医学 | 5992篇 |
眼科学 | 2421篇 |
药学 | 8860篇 |
71篇 | |
中国医学 | 5476篇 |
肿瘤学 | 6183篇 |
出版年
2024年 | 285篇 |
2023年 | 1197篇 |
2022年 | 2892篇 |
2021年 | 4288篇 |
2020年 | 3209篇 |
2019年 | 2552篇 |
2018年 | 2823篇 |
2017年 | 2564篇 |
2016年 | 2378篇 |
2015年 | 3884篇 |
2014年 | 4859篇 |
2013年 | 4424篇 |
2012年 | 6507篇 |
2011年 | 7151篇 |
2010年 | 4566篇 |
2009年 | 3986篇 |
2008年 | 4755篇 |
2007年 | 4800篇 |
2006年 | 4542篇 |
2005年 | 4355篇 |
2004年 | 2897篇 |
2003年 | 2755篇 |
2002年 | 2324篇 |
2001年 | 1854篇 |
2000年 | 1793篇 |
1999年 | 1651篇 |
1998年 | 1078篇 |
1997年 | 998篇 |
1996年 | 759篇 |
1995年 | 712篇 |
1994年 | 599篇 |
1993年 | 354篇 |
1992年 | 431篇 |
1991年 | 352篇 |
1990年 | 318篇 |
1989年 | 273篇 |
1988年 | 259篇 |
1987年 | 192篇 |
1986年 | 163篇 |
1985年 | 124篇 |
1984年 | 62篇 |
1983年 | 53篇 |
1982年 | 28篇 |
1981年 | 29篇 |
1980年 | 26篇 |
1979年 | 41篇 |
1976年 | 13篇 |
1974年 | 13篇 |
1972年 | 14篇 |
1968年 | 13篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
:15只恒河猴随机分为 2组 :实验组 10例 ,其人工血管均经自体静脉内皮细胞种植 ;对照组 5例 ,其人工血管均未经任何处理。实验组、对照组手术方法相同。将长 6cm、直径 3mmePTFE(膨体聚四氟乙烯 )人工血管近端与腹主动脉行端 -侧吻合、远端与髂总动脉行端 -端吻合。术后当日、1周及 4周 ,所有恒河猴均行静脉法数字减影造影术 ,术后 4周行彩色B型超声波检查 ,然后取出所有对照组及 9例实验组恒河猴腹腔内之人工血管 ,标本送光镜、扫描电镜及透射电镜检查。结果表明 ,术后 4周 ,对照组人工血管均不通畅 ,而实验组有 8条人工血管通畅良好。B超见全部对照组及 1例实验组人工血管腔内形成血栓 ,实验组 8条通畅之人工血管均保持较高的血流量。扫描电镜见实验组全部人工血管腔内均有一层完整融合的内皮细胞单层 ,而对照组人工血管腔内未见有内皮细胞。 相似文献
992.
Richardson MA Satz PF Myers HF Miller EN Bing EG Fawzy FI Maj M 《Journal of clinical and experimental neuropsychology》1999,21(6):769-783
The utility of self-report measures in identifying those at risk for depressive disorder and the adverse impact of depression versus depressed mood and HIV serostatus on neuropsychological (NP) test performance were examined in a large sample (N = 243) of gay and bisexual African American men. Results indicate high rates of depression relative to recent population estimates, regardless of methodology, but that the use of standard cut-scores for self-report inventories may significantly overestimate psychiatric morbidity. Limited independent effects of serostatus or depression on NP test performance were observed. More importantly, a complex set of adverse effects of depression and its interaction with serostatus which varied according to the methodology used to assess depression were observed. These findings are discussed in light of ongoing controversy regarding the relative influence of depression on neuropsychological functioning among people living with HIV/AIDS. 相似文献
993.
Tuberculosis versus lymphomas in the abdominal lymph nodes: evaluation with contrast-enhanced CT 总被引:24,自引:0,他引:24
Yang ZG Min PQ Sone S He ZY Liao ZY Zhou XP Yang GQ Silverman PM 《AJR. American journal of roentgenology》1999,172(3):619-623
OBJECTIVE: Tuberculosis in the abdominal lymph nodes may be difficult to distinguish from lymphomas. This study evaluated specific CT imaging criteria for differentiating these entities. MATERIALS AND METHODS: We retrospectively reviewed the anatomic distribution and CT enhancement patterns of disease in 69 patients, 26 (38%) with tuberculosis and 43 (62%) with untreated lymphomas involving abdominal lymph nodes. Of the patients with tuberculosis, five (19%) had disseminated disease and 21 (81%) had nondisseminated disease. Of the patients with lymphomas, 16 (37%) had Hodgkin's disease and 27 (63%) had non-Hodgkin's lymphoma. RESULTS: Disseminated and nondisseminated tuberculosis involved predominantly lesser omental, mesenteric, anterior pararenal, and upper paraaortic lymph nodes. Lower paraaortic lymph nodes were involved more often in Hodgkin's disease (15 patients [94%]), non-Hodgkin's lymphoma (24 patients [89%]), and disseminated tuberculosis (five patients [100%]) than in nondisseminated tuberculosis (one patient [5%]). Mesenteric lymph nodes were involved more often in disseminated tuberculosis (four patients [80%]) and nondisseminated tuberculosis (11 patients [52%]) than in Hodgkin's disease (one patient [6%]) (p < .01). Anatomic distribution was not different between disseminated tuberculosis and non-Hodgkin's lymphoma. Tuberculous lymphadenopathy commonly showed peripheral enhancement, frequently with a multilocular appearance, whereas lymphomatous adenopathy characteristically showed homogeneous attenuation (14 patients [87.5%] with Hodgkin's disease and 19 patients [70%] with non-Hodgkin's lymphoma [p < .01]). CONCLUSION: Our findings indicate that the anatomic distribution and specific enhancement patterns of lymphadenopathy seen on contrast-enhanced CT can be useful in differentiating between tuberculosis and untreated lymphomas of the abdominal lymph nodes. 相似文献
994.
The preventive effect of heparin on stricture formation after caustic esophageal burns 总被引:9,自引:0,他引:9
Bingöl-Kologlu M Tanyel FC Müftüoğlu S Renda N Cakar N Büyükpamukçu N Hiçsönmez A 《Journal of pediatric surgery》1999,34(2):291-294
BACKGROUND/PURPOSE: Preventing thrombus formation after caustic esophageal ingestion has been proposed to have beneficial effects. Therefore, an experimental study was carried out to investigate the effects of heparin on the esophagus after caustic burns. METHODS: Caustic esophageal burns were produced in rats by irrigation with 50% NaOH as described by Liu. Rats were divided into four groups as follows: group A, animals with esophageal burns, received placebo and underwent autopsy 48 hours after caustic injury; group B, animals with esophageal burns, received subcutaneous heparin treatment and underwent autopsy 48 hours after caustic injury; group C, animals with esophageal burns, received placebo and underwent autopsy 28 days after caustic injury; group D, animals with esophageal burns, received subcutaneous heparin treatment for 7 days and underwent autopsy 28 days after caustic injury. Histopathologic evaluation was performed in all groups, and collagen content of esophageal sections was analyzed by determination of hydroxyproline levels. RESULTS: Submucosal vascular thrombosis was encountered in all group A animals but the submucosal venules and arterioles were patent in most of group B animals. Esophageal strictures did not develop in any of group D animals, although varying degree of esophageal stenoses were encountered in all animals of group C. The circumferences of the burned segment have been narrowed to 3+/-1 mm in group C rats. There was obvious collagen deposition in submucosa, and epithelial regeneration was not complete in group C rats. Submucosa and epithelial integrity seemed normal in group D animals. Hydroxyproline contents in group D were significantly lower compared with group C (P < .05). CONCLUSIONS: Heparin has ameliorating effects on stricture formation after caustic esophageal burn. Those effects may occur through possible anticoagulant, antithrombotic, and endothelial protective effects, and modifying effects of heparin on wound healing. 相似文献
995.
A terminal transferase-mediated dUTP nick end labeling (TUNEL) method was utilized for detection of neuronal death in the subcortical relay nuclei of the trigeminosensory system following the infraorbital nerve transection in newborn rats. At 18-24 h after injury, numerous TUNEL-positive profiles were found within the ventroposteromedial thalamic nucleus (VPM) contralateral to the injury, whereas the VPM on the ipsilateral side and of the age-matched normal control contained only a few profiles per section. Electron microscopy revealed that the TUNEL-positive profiles were apoptotic neurons. The ventral part of the ipsilateral brainstem sensory trigeminal nuclear complex (the nucleus principalis, and the subnuclei oralis and interpolaris) exhibited statistically significant 65-70% increase in number of apoptotic neurons compared to the contralateral side. Taken together with our previous study [T. Sugimoto, C. Xiao, H. Ichikawa, Neonatal primary neuronal death induced by capsaicin and axotomy involves an apoptotic mechanism, Brain Res. 807 (1998) 147-154], the present results demonstrated a cascade of apoptosis in the primary, secondary and tertiary order sensory neurons along the neuroaxis. 相似文献
996.
We have shown that neuropsin is expressed in the neurons of the limbic system in the adult mouse. After the central nervous system was injured by incision or intraperitoneal kainate injection, neuropsin mRNA was induced in the peri-lesioned region. The cells in which neuropsin mRNA was induced were localized mainly in axon fiber pathways and closely associated to proteolipid protein (PLP) mRNA expressing oligodendrocytes. 相似文献
997.
To determine whether perturbations of haemostatic function and lipoprotein metabolism prevail long after preeclampsia and increase the risk of future coronary heart disease (CHD), we conducted a follow-up study in women with (cases, n = 25) or without (controls, n = 24) a history of preeclampsia. Blood samples were taken in the follicular and in the luteal phases of a menstrual cycle. Levels of blood pressure (BP) and proteinuria measured during the index pregnancy were included in the evaluation. Compared to control women who had undergone a normal pregnancy, the formerly preeclamptic patients had higher systolic (p <0.01) and diastolic (p <0.05) BPs and increased plasma levels of von Willebrand factor (vWF), fibrinogen, cholesterol, triglycerides and very low density lipoprotein (VLDL) (all p <0.05). The lipid, vWF, and fibrinogen levels were positively related to the degree of BP elevation but not to the degree of proteinuria during the index pregnancy. Except for the increase in vWF level, all biochemical perturbations were only present in the luteal but not in the follicular phase samples. In conclusion, persistent endothelial dysfunction with ensuing dysregulation of blood pressure, haemostatic perturbation and dyslipoproteinemia after preeclampsia may indicate a proneness to future CHD. 相似文献
998.
999.
BACKGROUND: Polypeptide growth factors are positive and negative regulators of prostatic growth and function, and many positive regulators of growth in the prostate have been extensively studied. However, very few inhibitors of prostate cell proliferation have been identified. We have isolated a unique 18-kDa sialoglycopeptide (CeReS-18) which inhibits cell proliferation of three separate lines of human prostate cancer cells, as well as inducing cellular cytotoxicity via an apoptotic pathway unrelated to the Bcl-2 family of proteins. METHODS: Cell cycle inhibition was analyzed by direct cell counts with a Coulter (Miami, FL) cell counter. Apoptotic cells were analyzed by electron microscopy, annexin V-fluorescein isothiocyanate (FITC) staining, fluorescence microscopy, and propidium iodide uptake measured with a fluorescence-activated cell sorter. Expression of the proteins of the Bcl-2 family was detected by Western blot analysis. RESULTS: We found that CeReS-18 inhibits cell proliferation of androgen-responsive, LNCaP.FGC human prostate cancer cells, as well as of androgen-nonresponsive DU-145 and PC3 human prostate cancer cells. Furthermore a, fivefold increase over the inhibitory concentration of CeReS-18 elicited a cytotoxic response by all three cell lines. We thus characterized the cytotoxic mechanism as apoptotic in nature, and we measured the expression of several members of the Bcl-2 family in PC3 cells upon treatment with CeReS-18. CONCLUSIONS: The data indicate that CeReS-18 is a potent inhibitor of cellular progression through the cell cycle by both androgen-responsive and androgen-nonresponsive human prostate cancer cells. In addition, treatment of both types of cells with increased concentrations of CeReS-18 induces cellular cytotoxicity, characterized as apoptosis. 相似文献
1000.
上海市婴幼儿血铅水平与体格发育的关系 总被引:24,自引:2,他引:22
目的探讨低水平铅暴露对儿童体格发育的影响。方法在上海市5个区县30所托幼机构,对1969名儿童进行了血铅水平的流行病学调查和体格发育等指标测量,并根据儿童身高、体重、头围和胸围计算其Z标准分,然后与血铅水平进行相关分析和逐步回归分析。结果上海市儿童血铅水平几何均数为0.400μmol/L,≥0.483μmol/L的比例为37.8%,血铅水平的几何均数与儿童身高、体重及头围的Z标准分呈显著的负相关。结论低水平铅暴露对上海市婴幼儿的体格发育可能具有不利影响。 相似文献