全文获取类型
收费全文 | 42155篇 |
免费 | 4011篇 |
国内免费 | 2524篇 |
专业分类
耳鼻咽喉 | 357篇 |
儿科学 | 674篇 |
妇产科学 | 386篇 |
基础医学 | 4343篇 |
口腔科学 | 744篇 |
临床医学 | 5177篇 |
内科学 | 5418篇 |
皮肤病学 | 563篇 |
神经病学 | 1737篇 |
特种医学 | 1747篇 |
外国民族医学 | 7篇 |
外科学 | 3673篇 |
综合类 | 8308篇 |
现状与发展 | 12篇 |
一般理论 | 2篇 |
预防医学 | 3939篇 |
眼科学 | 715篇 |
药学 | 4917篇 |
45篇 | |
中国医学 | 3190篇 |
肿瘤学 | 2736篇 |
出版年
2024年 | 160篇 |
2023年 | 553篇 |
2022年 | 1434篇 |
2021年 | 1923篇 |
2020年 | 1494篇 |
2019年 | 1191篇 |
2018年 | 1250篇 |
2017年 | 1323篇 |
2016年 | 1268篇 |
2015年 | 1957篇 |
2014年 | 2387篇 |
2013年 | 2715篇 |
2012年 | 3753篇 |
2011年 | 4026篇 |
2010年 | 2995篇 |
2009年 | 2426篇 |
2008年 | 2789篇 |
2007年 | 2714篇 |
2006年 | 2398篇 |
2005年 | 2053篇 |
2004年 | 1595篇 |
2003年 | 1513篇 |
2002年 | 1301篇 |
2001年 | 968篇 |
2000年 | 723篇 |
1999年 | 441篇 |
1998年 | 245篇 |
1997年 | 213篇 |
1996年 | 156篇 |
1995年 | 139篇 |
1994年 | 121篇 |
1993年 | 73篇 |
1992年 | 85篇 |
1991年 | 68篇 |
1990年 | 45篇 |
1989年 | 39篇 |
1988年 | 26篇 |
1987年 | 23篇 |
1986年 | 17篇 |
1985年 | 11篇 |
1984年 | 8篇 |
1983年 | 7篇 |
1981年 | 4篇 |
1979年 | 21篇 |
1978年 | 3篇 |
1977年 | 3篇 |
1976年 | 4篇 |
1970年 | 4篇 |
1969年 | 6篇 |
1968年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
目的:探讨河北汉族人群细胞色素P4501A2(cytochrome P4501A2,CYP1A2)C163A基因多态性的分布情况。方法应用聚合酶链式反应-限制性酶切片段长度多态性(PCR‐RFLP)方法对210例河北汉族正常人进行CYP1A2 C163A基因多态性分析。结果河北汉族人群CYP1A2 C163A基因A和C等位基因的频率为:68.3%、31.7%。AA、AC、CC基因型频率分别为48.1%、40.5%、11.4%。符合 Hardy‐Weinberg 遗传平衡定律(χ2=1.22,P>0.05),具有代表性。结论河北汉族人群CYP1A2基因存在C163A位点多态性。 相似文献
992.
Shoichiro Sumi MD Dr. Kazutomo Inoue MD Masafumi Kogire MD Ryuichiro Doi MD Mitsutoshi Yun MD Hiromu Kaji MD Ryo Hosotani MD Masaki Fujimura MD Kotaro Uchida MD Shinya Kiyama PhD Kouki Kitagawa PhD Haruaki Yajima PhD Nobutaka Fujii PhD Takayoshi Tobe MD 《Digestive diseases and sciences》1991,36(11):1523-1528
This study examined the effect of synthetic porcine neuropeptide Y on the splanchnic blood flows and the exocrine pancreatic secretion in dogs. Graded doses of neuropeptide Y (0.1–5 g/kg, intravenous) caused dose-dependent reduction of the secretin-stimulated exocrine pancreatic secretion and of the blood flows in the superior mesenteric artery, the portal vein, and the pancreatic tissue. Neuropeptide Y at 5 g/kg reduced the blood flows to 45.9±13.3% (superior mesenteric artery), 63.0±10.5% (portal vein), and 77.9±4.8% (pancreatic tissue), respectively. This dose also reduced secretin-stimulated pancreatic juice volume and CCK-8 plus secretin-stimulated protein output to 65.2±9.3 and 63.3±14.0%, respectively. This study shows a potent vasoconstrictor effect of neuropeptide Y on splanchnic vessels. Neuropeptide Y also inhibited exocrine pancreatic secretion in a significant correlation with the reduction in pancreatic tissue blood flow, which suggests that reduction in the blood flow may be one of the possible mechanisms of the inhibitory action of neuropeptide Y on exocrine secretion.This work was supported by a grant from the Ministry of Education, Japan (A-61440060). 相似文献
993.
994.
球囊拉伤致家兔动脉粥样硬化斑块破裂及血栓形成 总被引:9,自引:1,他引:9
为建立动脉粥样硬化的兔模型并用药物触发造成斑块破裂及血栓形成,将60只雄性纯种新西兰兔随机平均分成三组:球囊损伤 高脂(1%胆固醇)组、高脂喂养组及普通饲料喂养组.喂养3个月后分别给予鲁塞尔蝰蛇毒和组胺药物触发以造成斑块破裂及血栓形成。结果发现,球囊损伤 高脂组与高脂喂养组均形成动脉粥样硬化斑块,其中球囊损伤 高脂组所形成的粥样斑块为具有较大脂质核的软斑块;药物触发后球囊损伤 高脂组存活的18只中有11只共15处发生斑块破裂及血栓形成;高脂喂养组中的19只经药物触发后仅5只共7处发生斑块破裂及血栓形成;普通饲料喂养组中未见斑块破裂及血栓形成。结果提示,在构建的动脉粥样硬化斑块的动物模型基础上,应用药物触发后能够造成斑块破裂及血栓形成。 相似文献
995.
韩云 杨生虎 李晓峰 杨立平 耿兴隆HAN Yun YANG Sheng-hu Li Xiao-feng YANG Li-ping GENG Xing-long 《中国内镜杂志》2015,21(1):13-16
目的探讨腹腔灌洗液中CK20m RNA的临床意义以及腹腔镜直肠癌根治术的临床应用价值。方法选择49例直肠癌手术患者,利用RT-PCR技术分别检测以上患者腹腔灌洗液中CK20m RNA表达,从而探究CK20m RNA的临床价值以及评价腹腔镜直肠癌根治术的临床实用性。结果 10例良性病变腹部手术组患者腹腔灌洗液中CK20m RNA无明显表达。39例结直肠癌患者腹腔灌洗液中可见CK20m RNA表达,术前、术中以及术后的总表达率为40.2%(47/117),且术前、术中以及术后CK20m RNA的表达率比较差异无显著性(P0.05)。17例开腹手术组和22例腹腔手术组术前、术中以及术后CK20m RNA阳性表达率的比较差异无显著性(P0.05)。结论腹腔镜结直肠癌根治术治疗结直肠癌安全有效,与开腹手术相比并不增加癌细胞局部种植的风险。 相似文献
996.
Two compatible conversion factors for converting diameter measurements taken at different breast heights were derived for Pinus radiata using taper data from more than 3000 trees. The two breast heights used for conversion were 1.3 and 1.4 m above ground, as defined in Australia and New Zealand, two major radiata-growing countries in the world. The conversion factors were estimated through three alternative statistical methods including simple least squares regression, seemingly unrelated regression and errors-in-variables models. The three sets of estimates were almost identical and had similar conversion accuracy, although the second method was slightly better. The conversion factors were more accurate than overbark taper equations used for the same purpose. The factor was 0.9916 for converting diameter measured at 1.3 to that at 1.4 m above ground, and the inverse of this value, 1.0084, was for the vice versa. When calculating tree and stand volume and biomass using equations with diameter at a different breast height as a predictor to that of the input data, the bias, either over or under estimation, could be between 1.67% and 2.00% without conversion. These conversion factors will facilitate the sharing of data among radiata growing countries with different definitions of breast height, but more importantly it will help correct the bias in stand volume and biomass estimation caused by the seemingly negligible difference in breast height when software for forest resource management and decision support developed in one country is applied in another. Such bias when accumulated over a large management area may not be financially insignificant for an astute forest management agency. 相似文献
997.
Yun Shao Xiaoying Li Yali Lu Lin Liu Po Zhao 《International journal of clinical and experimental pathology》2015,8(6):6560-6565
Background: The Leukemia related protein 16 gene (LRP16) localized on chromosome 11q12.1, is an important estrogen-responsive gene and a crucial regulator for NF-kB activation. LRP16 is frequently expressed in human cancers; however, the LRP16 gene remains unexplored in lung neuroendocrine tumors. The aim of this study was to investigate the role of LRP16 expression in primary lung neuroendocrine tumors. Methods: lung neuroendocrine tumors were analyzed for LRP16 gene expression by two-step non-biotin immunohistochemical method. Results: Fifty of ninety (55.6%) cases of neuroendocrine lung tumors tested were positive for LRP16 protein by immunohistochemistry. The expression of LRP16 was mainly located in cytoplasm and nucleus of tumor cells. LRP16 protein was corresponding to tumor type and clinical stage, as well as survival time. Conclusions: The results indicate that abnormal LRP16 expression is noted in neuroendocrine lung tumors and the expression can give insight into the pathogenesis of the disease. The LRP16 protein may serve as a potential marker in predicting prognosis of neuroendocrine lung tumors. 相似文献
998.
Yi Zhou Yun Xu Lujun Chen Bin Xu Changping Wu Jingting Jiang 《International journal of clinical and experimental pathology》2015,8(8):9428-9433
B7-H6, a newly identified B7 family member molecule, binds to its receptor on NK cells, NKp30, and then triggers the anti-tumor NK cell cytotoxicity and leads to the cytokine secretion. As of now, numerous studies have demonstrated that the higher B7-H6 expression could be found in certain human cancers and have important clinical significance. In our present study, we carried out the tissue microarray and the immunohistochemistry assay to investigate the clinical significance of B7-H6 expression in human ovarian cancer. Our results showed that the positive B7-H6 staining was predominantly observed on the membrane and in the cytoplasm of the ovarian cancer cells. In order to further investigate the correlation between clinical parameters and the B7-H6 protein levels in the ovarian tissues, we categorized all the 110 patients into two major subgroups according to the intensity of B7-H6 immunohistochemical staining, i.e., the lower B7-H6 expression group, 34 cases (0 ≤ H-score < 100), and the higher B7-H6 expression group, 76 cases (H-score ≥ 100), and we found that B7-H6 expression in the ovarian cancer tissues is significantly correlated with distant metastasis status (P = 0.028) and FIGO stage (P = 0.031), whereas it is not correlated with patient’s age, tumor size, tumor location, pathological stage or nodal metastasis. The survival analysis demonstrated that the overall survival rate of the subgroup with lower B7-H6 expression is significantly better than that of the subgroup with higher B7-H6 expression (P = 0.0456, Hazard Ratio: 1.707, 95% CI, 1.010-2.885). Thus, our present data revealed that higher B7-H6 expression in ovarian cancer tissues was positively correlated with tumor metastasis and cancer progression, and supports the notion that B7-H6 expression is involved in the progression of human ovarian cancer, the detailed mechanism merits further investigation. 相似文献
999.
Fan Zeng Kui Liao Jiayan Wu Yue Gao Haiyu Li Jianjun Fan Hantao Zhang Yun Li Xin Bai Geili Liu Fangzhou Song 《International journal of clinical and experimental pathology》2015,8(8):9434-9439
The armadillo repeat proteins were first found in armadillo gene of Drosophila. Since then a number of proteins containing armadillo repeats have been noticed and studied. These proteins that consist of 6 to 13 armadillo repeat domains are classified as family of armadillo repeat proteins. Recently, several studies indicated that armadillo repeat family of proteins play an important role in the tumorigenesis and maintenance of tissue integrity. ALEX1 (Arm protein lost in epithelial cancers, on chromosome X), contains two armadillo repeats domains, is expressed different in normal and carcinomas tissues. Several studies have found that ALEX1 protein lost in tumors that originated in epithelial tissues. We evaluated the ALEX1 protein expression in 53 cervical cancers and in 53 non-cancerous cervical tissues from patients and adjacent non-cancerous tissues using immunohistochemistry Results: ALEX1 protein expression is significantly increased in 53 cervical cancers tissues compared with non-cancerous tissues. We found, for the first time, that ALEX1 protein expression in cervical cancers tissues is higher than non-cancerous tissues. It is suggested that the ALEX1 protein is associated with tumorigenesis in cervical cancer and we speculate that the ALEX1 may plays a role as an oncogene in cervical cancer. Moreover, ALEX1 may serve as a novel potential diagnostic biomarker in identifying cervical cancer. 相似文献
1000.
Su-Min Kim Jae-Won Choi Young-Chan Jeon Chang-Mo Jeong Mi-Jung Yun So-Hyoun Lee Jung-Bo Huh 《The journal of advanced prosthodontics》2015,7(4):303-311
PURPOSEThe aim of this study was to compare the changes in retentive force of stud attachments for implant overdentures by in vitro 2-year-wear simulation.RESULTSA comparison of the initial retentive force revealed the highest value for Kerator, followed by the O-ring and EZ lock attachments. However, no significant difference was detected between Kerator and O-ring (P>.05). After 2500 insertion and removal cycles, the highest retention loss was recorded for O-ring, and no significant difference between Kerator and EZ lock (P>.05). Also, Kerator showed the highest retentive force, followed by EZ lock and O-ring, after 2500 cycles (P<.05). Based on SEM analysis, the polymeric components in O-ring and Kerator were observed to exhibit surface wear and deformation.CONCLUSIONAfter 2500 insertion and removal cycles, all attachments exhibited significant loss in retention. Mechanism of retention loss can only be partially explained by surface changes. 相似文献