全文获取类型
收费全文 | 50333篇 |
免费 | 4214篇 |
国内免费 | 1898篇 |
专业分类
耳鼻咽喉 | 300篇 |
儿科学 | 883篇 |
妇产科学 | 2654篇 |
基础医学 | 10981篇 |
口腔科学 | 1681篇 |
临床医学 | 3819篇 |
内科学 | 4940篇 |
皮肤病学 | 1258篇 |
神经病学 | 2967篇 |
特种医学 | 1050篇 |
外国民族医学 | 21篇 |
外科学 | 3338篇 |
综合类 | 7507篇 |
现状与发展 | 13篇 |
一般理论 | 14篇 |
预防医学 | 3959篇 |
眼科学 | 963篇 |
药学 | 5584篇 |
20篇 | |
中国医学 | 1161篇 |
肿瘤学 | 3332篇 |
出版年
2024年 | 64篇 |
2023年 | 528篇 |
2022年 | 1083篇 |
2021年 | 1606篇 |
2020年 | 1389篇 |
2019年 | 1439篇 |
2018年 | 1383篇 |
2017年 | 1566篇 |
2016年 | 1656篇 |
2015年 | 1653篇 |
2014年 | 2584篇 |
2013年 | 3550篇 |
2012年 | 2576篇 |
2011年 | 2847篇 |
2010年 | 2499篇 |
2009年 | 2282篇 |
2008年 | 2276篇 |
2007年 | 2431篇 |
2006年 | 2278篇 |
2005年 | 2083篇 |
2004年 | 1943篇 |
2003年 | 1767篇 |
2002年 | 1490篇 |
2001年 | 1298篇 |
2000年 | 1116篇 |
1999年 | 1010篇 |
1998年 | 961篇 |
1997年 | 899篇 |
1996年 | 890篇 |
1995年 | 858篇 |
1994年 | 722篇 |
1993年 | 699篇 |
1992年 | 594篇 |
1991年 | 555篇 |
1990年 | 411篇 |
1989年 | 428篇 |
1988年 | 363篇 |
1987年 | 286篇 |
1986年 | 246篇 |
1985年 | 408篇 |
1984年 | 343篇 |
1983年 | 235篇 |
1982年 | 262篇 |
1981年 | 220篇 |
1980年 | 169篇 |
1979年 | 119篇 |
1978年 | 118篇 |
1977年 | 71篇 |
1976年 | 63篇 |
1975年 | 35篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
以小麦(Triticum aestivum L.)品种石4185为材料,研究了45 ℃处理0~120 min对小麦未成熟籽粒谷甘胱肽转移酶(GST)、谷胱甘肽还原酶(GR)、过氧化氢酶(CAT)和过氧化物酶(POD)活性, 超微弱发光,种子萌发和愈伤组织诱导的影响.结果表明,热休克处理使未成熟籽粒萌发率、愈伤组织诱导率和GST活性明显增加,且其作用随处理时间的延长而增大;在处理过程中, CAT活性先减少后增加,热休克对GR活性无明显影响.GST的活性与蛋白质质量分数呈显著正相关. 相似文献
52.
The nocturnal jejunal migrating motor complex: defining normal ranges by study of 51 healthy adult volunteers and meta-analysis 总被引:2,自引:0,他引:2
s. m. scott c. h. knowles d. wang † e. yazaki ‡ l. picon § d. l. wingate ‡ & g. lindberg ¶ 《Neurogastroenterology and motility》2006,18(10):927-935
Interdigestive human small bowel motility is characterized by the migrating motor complex (MMC). The aims of this study were to: (i) establish the normal range of variables of the nocturnal jejunal MMC and (ii) incorporate these data in a subsequent meta-analysis. Eighty-one recordings were performed by prolonged (24 h) ambulatory manometry in 51 subjects in two centres. Quantitative analysis was undertaken of 419 Phase III and 332 Phase II episodes. Adjusted mean values of seven variables were calculated using a mixed-effects model. Meta-analysis of pooled published data to generate a reliable 95% reference range was also performed. Adjusted mean values and confidence intervals are presented for all seven variables. Intrasubject variances were large in comparison with intersubject. Meta-analysis of 19 studies (356 pooled patients) meeting inclusion criteria produced wide reference ranges. At least five such ranges are useful for the detection of abnormality in the individual. This is the largest study of normal volunteers presented to date, with ranges for many variables produced using appropriate statistical methodology. A model for definition of abnormality has been proposed. We recommend that these data may be used by investigators in this field as a complement to other existing indicators of small bowel dysmotility. 相似文献
53.
54.
目的将激光显微分离(laser capture microdissection, LCM) 技术应用于噬菌体表面呈现肽库的筛选过程,建立一种可以直接在天然组织中筛选肽库的方法。方法将新鲜人骨肉瘤组织块在噬菌体肽库溶液振荡孵育后制成组织冰冻切片,免疫组化染色检测噬菌体在组织中的浸润扩散。改进常规LCM切片处理方法,以冻干法替代酒精/二甲苯法脱水,以期在LCM操作过程中提高切片上噬菌体的存活率。LCM法分离摄取骨肉瘤切片上的肿瘤靶细胞,转染回收这些细胞上特异结合的噬菌体。滴定法检测所筛选的噬菌体对特异性细胞的亲和力。结果利用LCM技术,可以由肿瘤冰冻切片上收集到足够的与特异性噬菌体短肽,应用于噬菌体表面呈现肽库筛选。经过3轮筛选后所获得的噬菌体与人骨肉瘤组织的特异性亲和力提高16倍。结论本研究首次将LCM技术应用于噬菌体表面呈现肽库的筛选,可以使我们直接在新鲜人肿瘤组织中筛选与特定细胞群甚至单个细胞亲合的短肽;同时又避免了天然组织中其他杂质细胞的污染,为研制细胞特异性导向载体提供了一个新的途径。 相似文献
55.
血清乙型肝炎病毒标志物不同表现模式及肝功能异常对肾移植受者存活率的影响 总被引:1,自引:0,他引:1
目的 探讨血清乙型肝炎病毒标志物不同表现模式对肾移植受者长期存活的影响。方法 对 62例血清乙型肝炎病毒标志物阳性者及 1 96例血清乙型肝炎病毒标志物全阴性者肾移植术后的肝功能、人肾均存活的存活率等指标进行随访和回顾性分析。结果 术后早期血清乙型肝炎病毒标志物阳性组与血清乙型肝炎病毒标志物阴性组比较 ,肝功能异常发生率的差异无显著性 (P >0 .0 5) ;术后中远期 ,HBsAg、HBeAg及抗 HBc阳性者的肝功能受损率明显高于血清乙型肝炎病毒标志物阴性组及HBsAg、抗 HBe、抗 HBc阳性者 (P <0 .0 5) ,其人肾均存活的存活率也最低 (P <0 .0 5)。结论 对HBsAg、抗 HBe及抗 HBc阳性者进行肾移植应慎重 ,而HBsAg、HBeAg及抗 HBc阳性者则不适宜接受肾移植 相似文献
56.
Akitoshi Yamada Yoshitaka Takeda Satoru Hayashi Kazuta Shimizu 《The Japanese Journal of Thoracic and Cardiovascular Surgery》2003,51(9):456-458
We experienced a case of familial spontaneous pneumothorax in three generations. Six of 13 family members had episodes of
spontaneous pneumothorax. It is well established that there are some diseases associated with human leukocyte antigen (HLA).
We performed HLA phenotyping for HLA of A, B and C. In our study, we detected the HLA haplotype A2, B61 in three of 4 who
had episodes of spontaneous pneumothorax. The HLA haplotype A2, B70 were also detected in three of 4 who had episodes. This
suggests that familial spontaneous pneumothorax might have hereditary factors. 相似文献
57.
用人喉癌手术切除标本建立了裸鼠移植瘤模型,已传至13代。原代移植成功率为66.7%,潜伏期30~70d;鼠间传代移植成功率为100%,潜伏期14~19d,生长稳定。经光学显微镜检查,各代移植瘤组织结构与原人喉癌组织基本一致。电镜检查证明,具有人喉癌特征,癌细胞间有大量桥粒,细胞浆中可见张力原纤维,有的张力原纤维与桥粒相连。细胞表面有较大的指状突,核膜较规则,胞浆中线粒体较多。 相似文献
58.
Kazutoshi Hori Kunio Uematsu Hitoshi Yasoshima Aklhiko Yamada Kazunari Sakurai Munehiko Ohya 《Pathology international》1997,47(9):592-599
Testicular seminoma with elevated serum human chorionic gonadotropin level (hCG-positive seminoma) is regarded as more malignant than marker-negative seminoma, although Its prognosis is still unclear. To clarify the malignant potential of seminoma with hCG production, the serum levels of the beta subunit of hCG (β-hCG) and lactic acid dehydrogenase (LDH) were examined in 35 and 40 patients, respectively, and the Immunohistochemical expression of β-hCG examined in 45 tumors. The elevation of the LDH serum level correlated to the Invasive status, metestatic status and poor outcome, while that of the serum β-hCG level correlated only to the metastatic status. Immunohistochemical expression of β-hCG was observed in syncytiotrophoblastic giant cells in 11 tumors and a few mononuclear seminoma cells In 36 tumors. Expression was not associated with the malignancy potential, except where the expression In mononuclear cells Inversely correlated to the invasive status. These results suggest that most seminomas produce a slight amount of hCG; that an elevated hCG serum level Indicates the pressnce of metastatic tumors and mainly reflects an increase in tumor volume but not in cellular malignancy potential; and that the LDH serum level, rather than hCG, is more useful as a prognostic indicator for patients with seminoma. 相似文献
59.
Mary Steidl Matsui Isabella Illarda Nianci Wang Vincent A. DeLeo 《Experimental dermatology》1993,2(6):247-256
Abstract Several lines of evidence implicate protein kinase C (PKC) in the development of basal cell and squamous cell carcinomas, tumors which originate from epidermal keratinocytes. To examine PKC in a model relevant to human skin, we exposed normal human epidermal keratinocytes (NHEK) in serum-free media to a variety of PKC agonists and antagonists. NHEK PKC activity increased up to 10-fold within the 1st hour of exposure to tetradecanoyl phorbol acetate (TPA), and gradually returned to control values within 72 h. TPA-induced PKC activity was enhanced by pretreatment of cultures with protein and RNA synthesis inhibitors. TPA-induced growth arrest and differentiation was antagonized by staurosporine. Down-regulation by bryostatin pretreatment blocked TPA-stimulated differentiation. Our overall conclusion is that activation of PKC in cultured human keratinocytes is required for differentiation. These results are crucial to the analysis of compounds suspected of promoting or inhibiting epidermal tumors. 相似文献
60.