全文获取类型
收费全文 | 75254篇 |
免费 | 7715篇 |
国内免费 | 5208篇 |
专业分类
耳鼻咽喉 | 653篇 |
儿科学 | 805篇 |
妇产科学 | 729篇 |
基础医学 | 8257篇 |
口腔科学 | 1110篇 |
临床医学 | 9777篇 |
内科学 | 10689篇 |
皮肤病学 | 598篇 |
神经病学 | 4038篇 |
特种医学 | 3008篇 |
外国民族医学 | 42篇 |
外科学 | 7825篇 |
综合类 | 14039篇 |
现状与发展 | 11篇 |
一般理论 | 11篇 |
预防医学 | 5398篇 |
眼科学 | 2255篇 |
药学 | 8187篇 |
96篇 | |
中国医学 | 4988篇 |
肿瘤学 | 5661篇 |
出版年
2024年 | 361篇 |
2023年 | 1335篇 |
2022年 | 3410篇 |
2021年 | 4291篇 |
2020年 | 3362篇 |
2019年 | 2669篇 |
2018年 | 2825篇 |
2017年 | 2508篇 |
2016年 | 2489篇 |
2015年 | 3619篇 |
2014年 | 4603篇 |
2013年 | 4239篇 |
2012年 | 6366篇 |
2011年 | 6542篇 |
2010年 | 4479篇 |
2009年 | 3615篇 |
2008年 | 4101篇 |
2007年 | 3997篇 |
2006年 | 3836篇 |
2005年 | 3441篇 |
2004年 | 2219篇 |
2003年 | 2068篇 |
2002年 | 1690篇 |
2001年 | 1315篇 |
2000年 | 1313篇 |
1999年 | 1328篇 |
1998年 | 803篇 |
1997年 | 809篇 |
1996年 | 625篇 |
1995年 | 548篇 |
1994年 | 475篇 |
1993年 | 282篇 |
1992年 | 371篇 |
1991年 | 292篇 |
1990年 | 278篇 |
1989年 | 213篇 |
1988年 | 217篇 |
1987年 | 195篇 |
1986年 | 176篇 |
1985年 | 141篇 |
1984年 | 82篇 |
1983年 | 62篇 |
1982年 | 39篇 |
1981年 | 33篇 |
1979年 | 50篇 |
1974年 | 44篇 |
1973年 | 35篇 |
1969年 | 40篇 |
1967年 | 32篇 |
1966年 | 33篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
人和大鼠腰椎关节突关节的SP能神经纤维的分布 总被引:2,自引:0,他引:2
目的:证实支配腰椎关节突关节的神经支配和化学性质,方法:用逆行荧光素标记结合免疫组化法,研究7只大鼠腰部脊神经节细胞的周围突分支投射到腰椎关节突关节及其递质性质以及3例人腰椎关节突关节囊上神经末梢的化学性质,结果:发现大鼠一侧L5和L6之间的关节突关节受同侧L2-5节段的脊神经节的部分细胞周围突分支支配,其中有33.399%的中型和小型细胞为中SP能免疫反应阳性,人的关节突关节囊含有SP阳性的神经 相似文献
72.
腰骶部SPR术中脊神经前后根定位的应用解剖 总被引:13,自引:6,他引:13
目的:为SPR提供可靠的术中脊神经前、后根鉴别的解剖学依据。方法:在20例成人脊柱标本上,去除后部结构,暴露整个马尾神经,对L1~S2节段的前后根进行形态学观察和测量。结果:脊神经后根位于马尾的后半部,前根则位于前半部。脊神经后根较相应的前根粗大,后根从L1~S1逐渐增大,以S1为最粗大;前根则以L3最粗大。相应前后根出硬脊膜前,有一段相互贴附并紧贴硬脊膜侧壁。结论:在多椎板切除SPR术中前、后根的定位及鉴别,暴露时可根据前、后根出硬脊膜前的相互贴附;在限制性椎板切除时则可通过脊髓外侧索和L1前、后根之间的最下端的齿状韧带加以鉴别 相似文献
73.
A novel active L1 retrotransposon subfamily in the mouse 总被引:8,自引:1,他引:8
Unlike human L1 retrotransposons, the 5' UTR of mouse L1 elements contains tandem repeats of approximately 200 bp in length called monomers. Multiple L1 subfamilies exist in the mouse which are distinguished by their monomer sequences. We previously described a young subfamily, called the T(F) subfamily, which contains approximately 1800 active elements among its 3000 full-length members. Here we characterize a novel subfamily of mouse L1 elements, G(F), which has unique monomer sequence and unusual patterns of monomer organization. A majority of these G(F) elements also have a unique length polymorphism in ORF1. Polymorphism analysis of G(F) elements in various mouse subspecies and laboratory strains revealed that, like T(F), the G(F) subfamily is young and expanding. About 1500 full-length G(F) elements exist in the diploid mouse genome and, based on the results of a cell culture assay, approximately 400 G(F) elements are potentially capable of retrotransposition. We also tested 14 A-type subfamily elements in the assay and estimate that about 900 active A elements may be present in the mouse genome. Thus, it is now known that there are three large active subfamilies of mouse L1s; T(F), A, and G(F), and that in total approximately 3000 full-length elements are potentially capable of active retrotransposition. This number is in great excess to the number of L1 elements thought to be active in the human genome. 相似文献
74.
H W Peng T S Su S H Han C K Ho C H Ho K N Ching B N Chiang 《Journal of medical virology》1988,24(4):405-412
In order to study the prevalence of hepatitis B virus (HBV) in the adult population of Taiwan, we screened for the presence of HBV DNA in 205 blood samples from adult (20-59-year-old) volunteers. According to the serological markers of HBV, samples were divided into three groups: group I (173 subjects) was negative for both HBsAg and HBeAg; group II (14 subjects) was positive for both HBsAg and HBeAg; and group III consisted of 18 subjects who were HBsAg-positive but HBeAg-negative. Plasma HBV DNA was not detected in group I, but it was found in 85.7% and 11.8% of samples in group II and group III, respectively. A free-form HBV DNA was found in 14.3% of the leukocyte samples in group II. Furthermore, an integrated form of HBV DNA was detected in the leukocytes of two cases of group I who remained healthy based on clinical data. HBV DNA was also detected in the spermatozoa and liver cells of one of the cases. 相似文献
75.
Yuan B. Peng Qing Lin W. D. Willis 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》1997,114(3):561-570
The effects of a protein kinase C (PKC) activator, 12-O-tetradecanoylphorbol-13-acetate (TPA), on the activity and periaqueductal gray (PAG)-induced inhibition of rat dorsal horn
neurons of the lumbar spinal cord were tested. A microdialysis fiber was placed through the dorsal horn for the purpose of
local application of pharmacological agents. Extracellular single-unit recordings from dorsal horn neurons were made near
the microdialysis fiber. TPA was tested on nociceptive dorsal horn cells. There was a significant increase in the background
activity and responses to ”brush”, with no changes in responses to pressure and pinch stimuli. TPA also significantly blocked
the PAG-induced inhibition of responses to brush, press, and pinch. These effects were eliminated by coadministration of the
PKC inhibitor NPC-15437. The solvent, which contained dimethyl sulfoxide, was also tested for its effect on the responses
to peripheral mechanical stimuli and PAG-induced inhibition of the dorsal horn neurons. There were no significant changes.
This experiment suggests that activation of the PKC second messenger system might increase the activity of dorsal horn neurons
and their responses to peripheral stimuli; in addition, the phorbol ester attenuated the PAG-induced descending inhibition
of the dorsal horn neuron activity.
Received: 15 May 1996 / Accepted: 14 November 1996 相似文献
76.
77.
Molecular cloning and sequence analysis of full-length cDNAs encoding new group of Cyn d 1 isoallergens 总被引:3,自引:0,他引:3
BACKGROUND: Cyn d 1, the major allergen of Bermuda grass pollen, contains some acidic/basic isoforms. The N-terminal amino acid sequences of some acidic Cyn d 1 isoforms were found to be different from those of Cyn d 1 cDNA clones identified previously. METHODS: A predicted 17-meric oligonucleotide probe was designed to fish the unidentified isoallergen cDNAs out of BGP cDNA library. The reactive clones were isolated and verified by sequencing. Two of them were expressed in the yeast Pichia pastoris to obtain recombinant Cyn d 1 proteins. RESULTS: All four cDNA clones encode the full-length Cyn d 1 with mature proteins of 244 amino acid residues. A 97-99% identity was found among the deduced amino acids of these four clones while an 86% identity was elicited between the four clones and the ones previously identified. The predicted isoelectric focusing (pI) values of the newly identified Cyn d 1s are acidic while pIs of the previously identified Cyn d 1s are basic. The two recombinant acidic Cyn d 1 proteins possess the epitopes recognized by mouse and rabbit polyclonal anti-Cyn d 1 antibodies, and have human IgE-binding capacity as revealed by immunodot assay. CONCLUSIONS: The present study identified full-length cDNAs encoding new isoallergens of Cyn d 1, and separated Cyn d 1 gene into an acidic group and a basic group. 相似文献
78.
酵母双杂合系统AD端阴离子交换蛋白C-末端表达质粒的构建 总被引:2,自引:0,他引:2
利用PCR方法,从阴离子交换蛋白1(AE1)全长cDNA中扩增出约350bp c末端cDNA片段,测序后将其克隆至pGADT7载体上,用醋酸锂法构建好的pADT7-AE1-c末端转染酵母菌HA109,观察其在选择性培养基上的表达情况。结果表明,获得了530bp AE1c-末端cDNA,pGADT7-AE1-c末端对酵母无毒性,不能激活检测基因,可作为酵母双杂合系统中的靶基因。 相似文献
79.
80.
Slobodan Jarić Dušan Ristanović Daniel M. Corcos 《European journal of applied physiology》1989,59(5):370-376
Summary Kinematic variables of the vertical jump (jumping height, jump phase durations and joint angles) were measured on 39 male
physical education students. In addition, kinetic parameters of the hip and knee extensors, and of the plantar flexors (maxima
voluntary force and its rate of development) were recorded on the same subjects, in isometric conditions. The results demonstrated
significant positive correlations between kinetic parameters of the active muscle groups and jumping height (r=0.217−0.464). The dominant effect on these correlations was due to the knee extensors. Correlations between these parameters
and the duration of the jump phases were much weaker. Correlation coefficients between kinetic parameters and limb angles
in the lowest body position showed that fast force production in one muscle group was related to a significant decrease in
the joint angles of distant body segments. Multiple correlation coefficients between leg extensor parameters and kinematic
variables (ranging between 0.256 for the duration of the counter-movement phase and 0.616 for jump height) suggested that
kinetic parameters could explain more than a quarter of the variability of this complex human movement. Therefore, the conclusion
was drawn that an extended set of measurements of the relevant musculo-skeletal system parameters could predict a considerable
amount of the variability of human movement. However, high correlation coefficients between the same kinetic parameters of
different muscle groups suggest that not all active muscle groups have to be included in the measurements. 相似文献