全文获取类型
收费全文 | 98436篇 |
免费 | 8102篇 |
国内免费 | 3926篇 |
专业分类
耳鼻咽喉 | 1011篇 |
儿科学 | 2426篇 |
妇产科学 | 1798篇 |
基础医学 | 10738篇 |
口腔科学 | 2033篇 |
临床医学 | 8714篇 |
内科学 | 12812篇 |
皮肤病学 | 1476篇 |
神经病学 | 3985篇 |
特种医学 | 4260篇 |
外国民族医学 | 60篇 |
外科学 | 12973篇 |
综合类 | 15939篇 |
现状与发展 | 21篇 |
一般理论 | 1篇 |
预防医学 | 3517篇 |
眼科学 | 1194篇 |
药学 | 8016篇 |
61篇 | |
中国医学 | 3267篇 |
肿瘤学 | 16162篇 |
出版年
2024年 | 221篇 |
2023年 | 1483篇 |
2022年 | 3778篇 |
2021年 | 4594篇 |
2020年 | 3611篇 |
2019年 | 3569篇 |
2018年 | 3500篇 |
2017年 | 3360篇 |
2016年 | 3376篇 |
2015年 | 3748篇 |
2014年 | 6118篇 |
2013年 | 6268篇 |
2012年 | 5668篇 |
2011年 | 6225篇 |
2010年 | 5149篇 |
2009年 | 4985篇 |
2008年 | 4935篇 |
2007年 | 5080篇 |
2006年 | 4393篇 |
2005年 | 3960篇 |
2004年 | 3430篇 |
2003年 | 2930篇 |
2002年 | 2497篇 |
2001年 | 2241篇 |
2000年 | 1902篇 |
1999年 | 1738篇 |
1998年 | 1608篇 |
1997年 | 1487篇 |
1996年 | 1243篇 |
1995年 | 1090篇 |
1994年 | 946篇 |
1993年 | 711篇 |
1992年 | 601篇 |
1991年 | 516篇 |
1990年 | 408篇 |
1989年 | 363篇 |
1988年 | 372篇 |
1987年 | 278篇 |
1986年 | 238篇 |
1985年 | 317篇 |
1984年 | 286篇 |
1983年 | 169篇 |
1982年 | 233篇 |
1981年 | 192篇 |
1980年 | 157篇 |
1979年 | 154篇 |
1978年 | 104篇 |
1977年 | 76篇 |
1976年 | 59篇 |
1975年 | 31篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
肿瘤转移抑制基因KAI1在喉鳞状细胞癌中表达的研究 总被引:1,自引:0,他引:1
目的 探讨肿瘤转移抑制基因KAI1在喉鳞状细胞癌 (简称鳞癌 )中的表达及其与之发生、发展的关系。方法 采用原位杂交方法检测 84例原发性喉鳞癌 (primarylaryngealsquamouscellcarcinoma ,PLSCC)、2 7例喉癌前病变不典型增生 (laryngealprecancerouslesion ,LPL)、10例声带息肉(vocalcordpolyp ,VCP)和 10例正常喉黏膜 (normallaryngealtissues ,NLT)石蜡标本组织细胞中KAI1mRNA的表达。结果 NLT、VCP、LPL和PLSCC 4种组织中KAI1阳性表达的积分吸光度值 ( x±s)分别为 (136 2 0 6 8± 36 6 75 5 )、(1336 74 5± 4 2 85 8 5 )、(90 36 8 8± 2 5 70 1 9)和 (6 7880 6± 2 8189 5 ) ,其中NLT组和VCP组之间差异无显著性 (t=0 14 2 ,P >0 0 5 ) ,NLT组和LPL组之间差异有显著性 (t =4 2 81,P <0 0 1) ;PLSCC组中KAI1表达普遍下调 ,且病理分化G1 2组阳性表达水平高于G3组 ;T1 2病变组高于T3 4组 ;颈淋巴结NO组高于N1及N1以上组 ;临床Ⅰ Ⅱ期组高于临床Ⅲ Ⅳ期组 (P值均 <0 0 1)。KAI1表达与患者性别无关 (P >0 0 5 )。结论 KAI1低表达在喉鳞癌的发生、发展中可能起着重要作用 ,可望作为喉鳞癌早期诊断、评估肿瘤细胞侵袭转移潜能及患者病程发展阶段的指标之一。 相似文献
32.
Calcifying odontogenic cyst (COC) has shown to be of extensive diversity in its clinical and histopathological features, as well as in its biological behavior. In this report, a rare case is described of ameloblastoma ex COC (dentinogenic ghost cell tumor) and the relevant literature is briefly reviewed. 相似文献
33.
Yoshie Ochiai Kazuhiro Kurisu Takashi Kajiwara Hiroshi Kumeda Ryuji Tominaga 《The Japanese Journal of Thoracic and Cardiovascular Surgery》2004,52(2):81-83
We describe a case of type B aortic dissection with large ascending aortic aneurysm occurring 12.8 years after aortic root
replacement (Cabrol procedure) in a non-Marfan patient with cystic medial necrosis of the aorta. We have successfully performed
an extended total aortic arch replacement using a four-branched graft through the “L-indsion” approach (a combination of a
left anterior thoracotomy and upper half median sternotomy). Of note, a histological specimen from the aneurysmal ascending
aortic wall revealed “healed aortic dissection” with fibrous tissue replacing the media and intima in addition to multiple
foci of cystic medial necrosis. 相似文献
34.
显微锁孔手术治疗脑干及其周围病变 总被引:4,自引:0,他引:4
目的 将显微锁孔手术应用于脑干及其周围病变的外科治疗,探求以最小的创伤来取得最佳的手术疗效。方法 采用颞下锁孔人路、乳突后锁孔人路、枕下正中锁孔人路,以20mm左右直径的骨窗进行脑干及其周围病变的显微手术治疗。结果 本组16例例病人术后3d内均行MRI或DSA检查,肿瘤或动静脉畸形全切除11例,次全切除3例,部分切除1例,1例小脑后下动脉瘤成功夹闭。术中输血3例。并发脑脊液耳漏1例,硬膜下积液1例,1例术后持续昏迷40d苏醒,无死亡及感染病例。结论 锁孔人路微创技术处理脑干及其周围病变,因其手术创伤小,疗效佳,费用节省,值得临床推广应用。 相似文献
35.
Microtubule-associated protein tau is required for axonal neurite elaboration by neuroblastoma cells. 总被引:5,自引:0,他引:5
NB2a/d1 neuroblastoma cells constitutively express multiple isoforms of the microtubule-associated protein tau and incorporate this protein into the axonal neurites elaborated during serum deprivation. To examine whether or not tau played an essential role in axonal outgrowth, cells cultured in serum-free medium were treated at 24 h intervals with antisense- and sense-oriented cDNA oligonucleotides (25 or 36 mers that span or are upstream of tau initiation codon) and were simultaneously serum deprived. Oligonucleotide uptake was confirmed by determination of intracellular levels of radiolabeled oligonucleotides. Treatment for 48 h with tau antisense oligonucleotides reversibly inhibited the expression of tau and the number of neurite-bearing cells compared with treatment with sense oligonucleotides. By contrast, tubulin expression was not affected. When cells were treated with antisense oligonucleotide simultaneously with serum deprivation, the initial outgrowth of neurites was unaffected, but continued neurite elongation was prevented. By contrast, neurite outgrowth at 4 h was inhibited when cells were pretreated with tau antisense 24 h before serum deprivation. Furthermore, intracellular delivery of anti-tau antiserum prevented neurite outgrowth and, in cells that had previously been deprived of serum for 24 h, induced retraction of existing neurites. These findings indicate that both the initiation and the continued outgrowth of neurites are dependent on tau and that pre-existing cytoplasmic pools of tau can mediate initial neuritogenesis. 相似文献
36.
37.
38.
Estil Y. Strawn Jr. MD Miles J. Novy MD Kenneth A. Burry MD Cynthia L. Bethea PhD 《American journal of obstetrics and gynecology》1995,172(6):1837-1844
Objective: Our purpose was to determine whether insulin-like growth factors I and II preferentially stimulate uterine leiomyoma cells versus myometrial cells in monolayer culture.Study design: Leiomyomas and normal myometrium were obtained at hysterectomy from five premenopausal women. Specimens were enzymatically digested for use in primary monolayer cell cultures. By use of serum-free media, insulin-like growth factor I or II was added in 1, 10, and 100 ng/ml concentrations to both cell types with the patient serving as her own control. Cell number, prolactin production, and proliferative index values were measured on day 15 of cell culture.Results: Significant increases in cell number were found in the leiomyoma cultures (p < 0.05) treated with 10 and 100 ng/ml insulin-like growth factors I but not with insulin-like growth factos II. Neither factor exerted a stimulatory effect on myometrial cells.Conclusion: Insulin-like growth factor sI preferentially stimulates leiomyoma cells in monolayer culture. These results suggest an autocrine-paracine role in vivo for this factor in conjuction with gonadal steroids in promoting leiomyoma growth. 相似文献
39.
MAP1a is a microtubule-associated protein with an apparent molecular weight of 360 kDa that is found in the axonal and dendritic processes of neurons. Two monoclonal anti-MAP1a antibodies, anti-A and anti-BW6, revealed different epitope distributions in the adult mouse cerebellum. Anti-A stained Purkinje and granule cells uniformly throughout the cerebellum. In contrast, anti-BW6 selectively stained the dendrites of a subset of Purkinje cells, revealing parasagittal bands of immunoreactivity in the molecular layer. The compartmentation of the BW6 epitope was compared to the Purkinje cells as revealed by immunostaining with anti-zebrin II, a well known antigen expressed selectively by bands of Purkinje cells. The anti-BW6 staining pattern was complementary to the zebrin II bands, the zebrin II- Purkinje cells having BW6+ dendrites. These results demonstrate that MAP1a is present in two forms in the mouse cerebellum, one of which is segregated into parasagittal bands. This may indicate a unique MAP1a isoform or may reflect differences in the metabolic states of Purkinje cell classes, and regional differences in their functions. 相似文献
40.
Takakura Yoshinobu Fujita Takuya Hashida Mitsuru Sezaki Hitoshi 《Pharmaceutical research》1990,7(4):339-346
As part of the strategy for the design of macromolecular carriers for drug targeting, the disposition characteristics of macromolecules were studied in mice bearing tumors that served as target tissues. Eight kinds of macromolecules including four polysaccharides and four proteins with different molecular weights and electric charges were used; tissue distribution and tumor localization after intravenous injection were studied. Pharmacokinetic analysis revealed that the tissue radioactivity uptake rate index calculated in terms of clearance was different among the tested compounds; especially, the urinary radioactivity excretion clearances and the total hepatic radioactivity uptake clearances varied widely. Compounds with low molecular weights (approximately 10 kD) or positive charges showed lower tumor radioactivity accumulation; radioactivity was rapidly eliminated from the plasma via rapid urinary excretion or extensive hepatic uptake, respectively. On the other hand, large and negatively charged compounds, carboxymethyl dextran, bovine serum albumin, and mouse immunoglobulin G, showed higher radioactivity accumulation in the tumor (calculated total amounts were 15.6, 10.8, and 20.8% of the dose, respectively) and prolonged retention in the circulation. These results demonstrated that the total systemic exposure rather than the uptake rate index was correlated with total tumor uptake. Molecular weight and electric charge of the macromolecules significantly affected their disposition characteristics and, consequently, determined radioactivity accumulation in the tumor. It was concluded that a drug–carrier complex designed for systemic tumor targeting should be polyanionic in nature and larger than 70,000 in molecular weight. 相似文献