全文获取类型
收费全文 | 50653篇 |
免费 | 5208篇 |
国内免费 | 3553篇 |
专业分类
耳鼻咽喉 | 379篇 |
儿科学 | 627篇 |
妇产科学 | 591篇 |
基础医学 | 5975篇 |
口腔科学 | 954篇 |
临床医学 | 6598篇 |
内科学 | 7450篇 |
皮肤病学 | 546篇 |
神经病学 | 2420篇 |
特种医学 | 1820篇 |
外国民族医学 | 27篇 |
外科学 | 5262篇 |
综合类 | 8559篇 |
现状与发展 | 16篇 |
一般理论 | 16篇 |
预防医学 | 3696篇 |
眼科学 | 1738篇 |
药学 | 5055篇 |
64篇 | |
中国医学 | 2969篇 |
肿瘤学 | 4652篇 |
出版年
2024年 | 193篇 |
2023年 | 905篇 |
2022年 | 2207篇 |
2021年 | 2868篇 |
2020年 | 2092篇 |
2019年 | 1845篇 |
2018年 | 1897篇 |
2017年 | 1696篇 |
2016年 | 1605篇 |
2015年 | 2377篇 |
2014年 | 2968篇 |
2013年 | 2730篇 |
2012年 | 3896篇 |
2011年 | 4297篇 |
2010年 | 2766篇 |
2009年 | 2246篇 |
2008年 | 2817篇 |
2007年 | 2639篇 |
2006年 | 2676篇 |
2005年 | 2376篇 |
2004年 | 1672篇 |
2003年 | 1445篇 |
2002年 | 1215篇 |
2001年 | 1053篇 |
2000年 | 1070篇 |
1999年 | 1081篇 |
1998年 | 685篇 |
1997年 | 613篇 |
1996年 | 510篇 |
1995年 | 427篇 |
1994年 | 416篇 |
1993年 | 239篇 |
1992年 | 306篇 |
1991年 | 252篇 |
1990年 | 224篇 |
1989年 | 236篇 |
1988年 | 175篇 |
1987年 | 175篇 |
1986年 | 96篇 |
1985年 | 97篇 |
1984年 | 59篇 |
1983年 | 39篇 |
1982年 | 29篇 |
1981年 | 32篇 |
1980年 | 25篇 |
1979年 | 30篇 |
1978年 | 12篇 |
1975年 | 11篇 |
1974年 | 16篇 |
1973年 | 13篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
52.
胆总管的矢状断层解剖研究 总被引:1,自引:0,他引:1
在30套成人腹部连续矢状断层标本上,胆总管与下腔静脉主要出现于R2-R3断层;胆总管胰腺段与胰头的关系有部分包埋,完全包埋及胰腺后型;十二指肠大乳头集中出现于R3断层;胆总管的行程有4种形式。文内还探讨了矢状断层里胆总管各段的毗邻及识别标志。 相似文献
53.
本文通过28例正常人及28例癌症病患者的头发的分析,得出癌症病患者的头发区别于正常人的头发的特征是:癌症病患者的头发中含有微量元素As、Ni、Mn。 相似文献
54.
肺动脉高压是多种因素导致的内皮功能受损所致,病理机制的研究进展为治疗开辟了新思路,提出了如钾离子通道开放剂、内皮素受体拮抗剂、蛋白激酶C抑制剂、PDE-5抑制剂和血栓素抑制等治疗方法. 相似文献
55.
Steffen Dietzel Anna Jauch Dirk Kienle Guoquiong Qu Heidi Holtgreve-Grez Roland Eils Christian Munkel Michael Bittner Paul S. Meltzer Jeffrey M. Trent Thomas Cremer 《Chromosome research》1998,6(1):25-33
Fluorescence in situ hybridization (FISH) with microdissection probes from human chromosomes 3 and 6 was applied to visualize arm and subregional band domains in human amniotic fluid cell nuclei. Confocal laser scanning microscopy and quantitative three-dimensional image analysis showed a pronounced variability of p- and q-arm domain arrangements and shapes. Apparent intermingling of neighbouring arm domains was limited to the domain surface. Three-dimensional distance measurements with pter and qter probes supported a high variability of chromosome territory folding. 相似文献
56.
57.
Monosomy for the short arm of chromosome 18 is one of the most frequent autosomal deletions observed. While most cases result from terminal deletion of 18p, 16% of cases reported were as a result of an unbalanced whole arm translocation resulting in monosomy 18p. The origin and structure of these derivative chromosomes were reported in only a few cases. We report the prenatal diagnosis and characterization of a new case of monosomy 18p as a result of an unbalanced whole arm translocation. Amniocentesis was performed at 15 weeks of gestation on a 34-year-old woman initially referred for advanced maternal age. Holoprosencephaly was identified by ultrasound at the time of amniocentesis. Karyotype analysis showed an unbalanced whole arm translocation between the long arm of one chromosome 18 and the long arm of one chromosome 22, 45,XX,der(18;22)(q10;q10), in all metaphases. In effect, the fetus had monosomy for 18p. Parental karyotypes were normal, suggesting a de novo origin for the der(18;22). Fluorescence in situ hybridization (FISH) analysis was performed with alpha-satellite probes D18Z1 and D14Z1/D22Z1 to identify the origin of the centromere on the der(18;22). Signal was observed with both probes, indicating that the centromere was composed of alpha-satellite DNA from both constituent chromosomes. Genotyping of the fetus and her parents with chromosome 18p STS marker D18S391 showed only the paternal 187 bp allele was present in the fetus, indicating that it was the maternal chromosome 18 involved in the der(18;22). This case and previous reports show that de novo unbalanced whole arm translocations are more likely to retain alpha-satellite sequences from the two chromosomes involved. 相似文献
58.
Proximal tubular epithelial cell integrins respond to high glucose by altered cell-matrix interactions and differentially regulate matrixin expression 总被引:11,自引:0,他引:11
Karamessinis PM Tzinia AK Kitsiou PV Stetler-Stevenson WG Michael AF Fan WW Zhou B Margaritis LH Tsilibary EC 《Laboratory investigation; a journal of technical methods and pathology》2002,82(8):1081-1093
Thickening of the tubular basement membrane (TBM) occurs in diabetic nephropathy, but the effects of high glucose on the functional aspects of proximal tubular epithelial cells are not clearly understood. In the present study, we examined the effects of elevated glucose concentrations on (a) integrin expression by human proximal tubular epithelial cells (HK-2) and integrin-mediated interactions with type IV collagen (colIV) and laminin, major components of TBM; (b) the expression of matrixins/matrix metalloproteinases (MMPs), which is regulated by integrins; and (c) the expression of tissue inhibitors of metalloproteinases (TIMPs). HK-2 cells cultured in 25 mM glucose underwent a reduction of the expression of alpha3, beta1, alpha(v)beta3, and alpha5 integrin subunits, with a concomitant increase of the alpha2 subunit, compared with cells grown in 5 mM glucose. Adhesion experiments demonstrated that high glucose led to increased cell adhesion on either colIV or laminin. Experiments of competition of adhesion using anti-integrin antibodies indicated that HK-2 cells in 5 mM glucose used mainly alpha(v)beta3 and alpha5beta1 integrins to adhere to colIV, whereas in 25 mM glucose they additionally used alpha2beta1. In the case of laminin, a beta1-mediated adhesion was observed when HK-2 cells were in 5 mM glucose, whereas in 25 mM glucose, alpha2beta1 and alpha(v)beta3 were also involved. Elevated glucose concentrations resulted in decreased expression of MMP-9 and MMP-2, whereas an increase in TIMP-1 and a decrease in TIMP-2 expression were observed. We also examined which integrins mediated the expression and secretion of matrixins MMP-2 and MMP-9. Ligation of alpha3beta1 with mAbs resulted in induction of MMP-2 expression and secretion, whereas antibody ligation of alpha(v)beta3 led to down-regulation of MMP-9. The above data implicate integrins of proximal tubular epithelial cells in the regulation of MMPs and in the development of TBM thickening in diabetic nephropathy. 相似文献
59.
Human chromosome 2 was formed by the head-to-head fusion of two ancestral chromosomes that remained separate in other primates. Sequences that once resided near the ends of the ancestral chromosomes are now interstitially located in 2q13-2q14.1. Portions of these sequences had duplicated to other locations prior to the fusion. Here we present analyses of the genomic structure and evolutionary history of >600 kb surrounding the fusion site and closely related sequences on other human chromosomes. Sequence blocks that closely flank the inverted arrays of degenerate telomere repeats marking the fusion site are duplicated at many, primarily subtelomeric, locations. In addition, large portions of a 168-kb centromere-proximal block are duplicated at 9pter, 9p11.2, and 9q13, with 98%-99% average sequence identity. A 67-kb block on the distal side of the fusion site is highly homologous to sequences at 22qter. A third ~100-kb segment is 96% identical to a region in 2q11.2. By integrating data on the extent and similarity of these paralogous blocks, including the presence of phylogenetically informative repetitive elements, with observations of their chromosomal distribution in nonhuman primates, we infer the order of the duplications that led to their current arrangement. Several of these duplicated blocks may be associated with breakpoints of inversions that occurred during primate evolution and of recurrent chromosome rearrangements in humans. 相似文献
60.
应用透射电镜和图象分析方法,对电针后大鼠中缝大核突触前终扣内突触囊泡的数量以及突触前终扣内容物的量的变化进行了研究。结果表明:电针后,中缝大核突触前终扣内圆形清亮囊泡和颗粒囊泡的数量明显减少,突触囊泡聚集并向突触活性带集中。图象分析结果:电针后,突触前终扣内容物的量较对照组明显减少,而且内容物分布不均匀并在突触膜附近集中。本实验为针刺镇痛的理论研究提供了形态学依据。 相似文献