全文获取类型
收费全文 | 10224篇 |
免费 | 458篇 |
国内免费 | 42篇 |
专业分类
耳鼻咽喉 | 107篇 |
儿科学 | 238篇 |
妇产科学 | 92篇 |
基础医学 | 1272篇 |
口腔科学 | 319篇 |
临床医学 | 648篇 |
内科学 | 2454篇 |
皮肤病学 | 488篇 |
神经病学 | 699篇 |
特种医学 | 487篇 |
外科学 | 1784篇 |
综合类 | 36篇 |
预防医学 | 200篇 |
眼科学 | 146篇 |
药学 | 532篇 |
中国医学 | 17篇 |
肿瘤学 | 1205篇 |
出版年
2023年 | 45篇 |
2022年 | 90篇 |
2021年 | 146篇 |
2020年 | 64篇 |
2019年 | 117篇 |
2018年 | 177篇 |
2017年 | 173篇 |
2016年 | 211篇 |
2015年 | 199篇 |
2014年 | 295篇 |
2013年 | 341篇 |
2012年 | 570篇 |
2011年 | 663篇 |
2010年 | 369篇 |
2009年 | 387篇 |
2008年 | 597篇 |
2007年 | 655篇 |
2006年 | 638篇 |
2005年 | 635篇 |
2004年 | 676篇 |
2003年 | 632篇 |
2002年 | 620篇 |
2001年 | 113篇 |
2000年 | 119篇 |
1999年 | 167篇 |
1998年 | 190篇 |
1997年 | 175篇 |
1996年 | 160篇 |
1995年 | 124篇 |
1994年 | 124篇 |
1993年 | 124篇 |
1992年 | 83篇 |
1991年 | 97篇 |
1990年 | 86篇 |
1989年 | 71篇 |
1988年 | 69篇 |
1987年 | 66篇 |
1986年 | 74篇 |
1985年 | 61篇 |
1984年 | 67篇 |
1983年 | 63篇 |
1982年 | 50篇 |
1981年 | 49篇 |
1980年 | 37篇 |
1979年 | 29篇 |
1978年 | 33篇 |
1977年 | 18篇 |
1976年 | 21篇 |
1974年 | 19篇 |
1973年 | 23篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
Atsushi Ohashi PhD Hirohisa Kotera BS Hideo Hori BS Makoto Hibiya PhD Koji Watanabe MD PhD Kazutaka Murakami MD PhD Midori Hasegawa MD PhD Makoto Tomita MD PhD Yoshinobu Hiki MD PhD Satoshi Sugiyama MD PhD 《Journal of artificial organs》2005,8(4):252-256
Polyvinyl chloride (PVC) tubing is an indispensable medical material for extracorporeal circulation therapy. However, di(2-ethylhexyl)phthalate
(DEHP), a suspected endocrine disruptor, can be eluted from PVC, suggesting that an alternative material that does not contain
DEHP is needed for clinical applications. First, we evaluated the endocrine disrupting risks of the plasticizers contained
in PVC tubes by investigating their binding affinities for the human estrogen receptor alpha (ERα). Our results revealed that,
while DEHP has some binding affinity for ERα, neither epoxidized soybean oil nor tris(2-ethylhexyl)trimellitate (an alternative
to DEHP) has any affinity for ERα. Second, we evaluated the endocrine disrupting risks of a tube made of newly developed plasticizer-free
(PF) materials. We confirmed the presence of DEHP and detected several unidentified substances in plasma stored within the
PVC tube. This plasma's competitive binding affinity for ERα was significantly higher than that of control plasma (P < 0.01). In contrast, the profile of plasma stored in the PF tube was similar to that of the control, both in terms of high-performance
liquid chromatography chromatograms and competitive binding capacity for ERα, suggesting that the PF tube is biocompatible
and is useful for reducing the elution of substances capable of binding to ERα.
Presented in part at the 42nd Congress of the Japanese Society for Artificial Organs, October 5–7, 2004, Tokyo, Japan 相似文献
82.
Neural mechanisms of three-dimensional vision 总被引:2,自引:0,他引:2
We can see things in three dimensions because the visual system re-constructs the three-dimensional (3D) configurations of objects from their two-dimensional (2D) images projected onto the retinas. The purpose of this paper is to give an overview of the psychological background and recent physiological findings concerning three-dimensional vision. Psychophysical and computational studies have suggested that in the visual system the 3D surface orientation is first estimated independently from individual depth cues--such as binocular disparity, as well as various monocular cues including texture gradients--and then the information from these different depth cues is integrated to construct a generalized representation of the 3D surface geometry. Neurons involved in low-level disparity processing, or the detection of local absolute disparity, were found mainly in the occipital cortex, whereas neurons involved in high-level disparity processing, or the reconstruction of 3D surface orientation through the computation of disparity gradients, were found mainly in the parietal area caudal intraparietal sulcus (CIP). Neurons sensitive to texture gradients, which is one of the major monocular cues, were also found in CIP. The majority of these neurons were sensitive to disparity gradients as well, suggesting their involvement in the computation of 3D surface orientation. In CIP, neurons sensitive to multiple depth cues were widely distributed together with those sensitive to a specific depth cue, suggesting CIP's involvement in the integration of depth information from different sources. In addition, human and monkey imaging studies have indicated convergence of multiple depth cues in CIP. These neurophysiological findings suggest that CIP plays a critical role in 3D vision by constructing a generalized representation of the 3D surface geometry of objects. 相似文献
83.
A histological evaluation for guided bone regeneration induced by a collagenous membrane 总被引:5,自引:0,他引:5
Taguchi Y Amizuka N Nakadate M Ohnishi H Fujii N Oda K Nomura S Maeda T 《Biomaterials》2005,26(31):6158-6166
This study was designed to evaluate the histological changes during ossification and cellular events including osteogenic differentiation responding to collagenous bioresorbable membranes utilized for GBR. Standardized artificial bony defects were prepared at rat maxillae, and covered with a collagenous bioresorbable membrane. These animals were sacrificed at 1, 2, 3 and 4 weeks after the GBR-operation. The paraffin sections were subject to tartrate resistant acid phosphatase (TRAP) enzyme histochemistry and immunohistochemistry for alkaline phosphatase (ALP), osteopontin (OP) and osteocalcin (OC). In the first week of the experimental group, woven bone with ALP-positive osteoblasts occupied the lower half of the cavity. The collagenous membrane included numerous ALP-negative cells and OP-immunoreactive extracellular matrices. At 2 weeks, the ALP-, OP- and OC-immunoreactivity came to be recognizable in the region of collagenous membrane. Since ALP-negative soft tissue separated the collagenous membrane and the new bone originating from the cavity bottom, the collagenous membrane appeared to induce osteogenesis in situ. At 3 weeks, numerous collagen fibers of the membrane were embedded in the adjacent bone matrix. At 4 weeks, the membrane-associated and the cavity-derived bones had completely integrated, showing the same height of the periosteal ridge as the surrounding alveolar bones. The collagen fibers of a GBR-membrane appear to participate in osteogenic differentiation. 相似文献
84.
The effect of electro-acupuncture stimulation (EAS) on duodenal motility was examined in anesthetized, artificially ventilated rats. EAS was applied to the abdominal area or to a hindpaw for 30 s at stimulus intensities of 0.1-10.0 mA with a stimulus frequency of 20 Hz. The duodenal motility was measured using the balloon method at a position about 1.5 cm caudal from the pylorus. Duodenal motility was inhibited by EAS at intensities of more than 5.0 mA (suprathreshold of group IV afferent excitation) when applied to the abdominal area. The duodenal inhibitory response existed after bilateral vagotomy or spinal transection, but was abolished by sectioning bilateral splanchnic nerves. Duodenal motility was facilitated by EAS at intensities of more than 2.0 mA (subthreshold of group IV, and suprathreshold for groups II+III afferent excitation) when applied to a hindpaw. The duodenal facilitatory response by EAS to a hindpaw existed after sectioning the splanchnic nerves, but disappeared after bilateral vagotomy or spinal transection. Furthermore, repetitive electrical stimulation of vagal efferent nerves enhanced duodenal motility, while repetitive electrical stimulation of the splanchnic efferent nerves inhibited the motility. It was concluded that the inhibitory response of duodenal motility elicited by EAS to the abdominal area is a spinal reflex response involving splanchnic inhibitory efferent nerves, and the enhanced response of duodenal motility by EAS to a hindpaw is a supraspinal reflex response involving vagal excitatory nerves. 相似文献
85.
Blood supply to the retina and the lens in the gerbil (<Emphasis Type="Italic">Meriones unguiculatus</Emphasis>) 总被引:1,自引:0,他引:1
Imada H Isomura G Miyachi E 《Anatomical science international / Japanese Association of Anatomists》2003,78(1):36-41
The blood supply to the retina and the lens in 32 gerbils (Meriones unguiculatus) of both sexes from infancy to maturity was studied under light and stereoscopic microscopes, and a scanning electron microscope.
Mercox (CL-2R; Dai Nippon Ink, Tokyo, Japan) was injected into the left ventricle of 30 animals in order to visualize the
blood supply to the retina and the lens from the ophthalmic artery. The central retinal artery arises from the ophthalmic
artery, passes through the papilla of the optic nerve together with the central retinal vein and penetrates the vitreous space
(cavity of the eye) between the lens and the internal limiting membrane of the retina, where it divides into the central branches
covering the lens and the parietal branches to supply the retina. The former passes through the hyaloid space after branching
several arterioles and then covers the lens like a network from its medial and marginal sides. Different from small experimental
animals, the parietal branches, just after separating from the central one, divides into the nasal, dorsal and temporal branches
in the vitreous space, each of which then subdivides to distribute across the retina on the inner limiting membrane, then
delineates the membrana vasculosa retinae. This basal pattern of vasculization 1 day after birth continues to death. Both
the central and parietal branches of the central retinal artery correspond to the branches of the hyaloid artery in embryo
and the latter is preserved in adult gerbils. 相似文献
86.
Shouji Iwatsuki Hideo Kasahara Yuya Yamashita 《Macromolecular chemistry and physics.》1967,104(1):254-262
RANEY metals (Ni, Fe, Co), URUSHIBARA metals (Ni, Co) and ULIMANN cu initiate the polymerization of methylmethacrylate. Diamines, diols or organic halides enhance their reactivity. In the presence of CCl4, the polymerization rate (Rp) is proportional to the square root of the amount of both metals and CCl4, and to the first power of the monomer concentration, but Rp becomes constant and independent of the concentration of CCl4 when there is a great excess of CCl4. We concluded that this polymerization follows the free radical mechanism and the participation of a zero-valent metal atom in the initiation reaction including complex formation between metal and CCL4 is suggested. 相似文献
87.
Takahashi HK Xue D Iwagaki H Tamura R Katsuno G Yagi T Yoshino T Mori S Nishibori M Tanaka N 《Clinical immunology (Orlando, Fla.)》2005,115(1):85-92
Prostaglandin E1 (PGE1) has therapeutic value for transplantations due to its microvascular activity. Interleukin (IL)-18, which is elevated in plasma during the acute rejection after organ transplantation, elicits the expression of intercellular adhesion molecule (ICAM)-1, B7.1, B7.2, CD40, and CD40 ligand (CD40L) on monocytes as well as the production of interferon (IFN)-gamma and IL-12 and proliferation of T-cells during the human mixed lymphocyte reaction (MLR) in an in vitro model of acute rejection. In contrast, PGE1 inhibits all the adhesion molecule expression, cytokine production and T-cell proliferation in the presence of IL-18. The effects of PGE1 depend on stimulation of the IP/EP2/EP4-receptor, and thus, PGE1 might have therapeutic potential for treating acute rejection due to its immune regulatory effect. 相似文献
88.
We develop a compact scanning head for use in laser confocal fluorescence microscopy for in situ fluorescence imaging of organs. The head, cylindrical in shape, has 3.5 mm diameter and 30 mm length, and is thus small enough to operate in a living rat heart. The lateral and axial resolutions, defined as full widths at half maximum (FWHM) of a point spread function (PSF), measures 1.0 and 5.0 microm, respectively, for 488-nm excitation and 1.0 and 5.4 microm, respectively, for 543-nm excitation. The chromatic aberration between 488- and 543-nm laser beams is well suppressed. We perform Ca2+ imaging in cardiomyocytes through the right ventricular chamber of a perfused rat heart in line-scan mode with 2.9-ms time resolution. We also carried out two-color imaging of a fixed mouse heart and liver with subcellular resolution. The compact head of the microscope equipped with a line-scan imaging mode and two-color imaging mode is useful for in situ imaging in living organs with subcellular resolution and can advantageously be applied to in vivo research. 相似文献
89.
By combining cell surface staining with fluorochrome-conjugated monoclonal antibodies and Hoechst 33342 dye supravital staining, Matsuzaki et al. have succeeded in enriching hematopoietic stem cells (HSCs) essentially to homogeneity. When single-cell transplantation analysis was performed using the isolated cells, over 95% of the recipient mice showed long-term multilineage engraftment. The work demonstrates unexpectedly high marrow seeding efficiency of HSCs and proposes high marrow homing capacity as a new criterion for HSCs. 相似文献
90.
Tachibana H Matsumoto N Cheng XJ Tsukamoto H Yoshihara E 《Clinical and diagnostic laboratory immunology》2004,11(6):1085-1088
We previously produced, in Escherichia coli, a human monoclonal antibody Fab fragment, CP33, specific for the galactose- and N-acetyl-D-galactosamine-inhibitable lectin of Entamoeba histolytica. To prepare antibodies with a higher affinity to the lectin, recombination PCR was used to exchange Ser91 and Arg96 in the third complementarity-determining region of the light chain with other amino acids. The screening of 200 clones of each exchange by an indirect fluorescent antibody test showed that 14 clones for Ser91 and nine clones for Arg96 reacted strongly with E. histolytica trophozoites. Sequence analyses revealed that the substituted amino acids at Ser91 were Ala in five clones, Gly in three clones, Pro in two clones, and Val in two clones, while the amino acid at position 96 was substituted with Leu in three clones. The remaining eight clones exhibited no amino acid change at position 91 or 96. These mutant Fab fragments were purified and subjected to a surface plasmon resonance assay to measure the affinity of these proteins to the cysteine-rich domain of lectin. Pro or Gly substitution for Ser91 caused an increased affinity of the Fab, but substitution with Ala or Val did not. The replacement of Arg96 with Leu did not affect affinity. These results demonstrate that modification of antibody genes by recombination PCR is a useful method for affinity maturation and that amino acid substitution at position 91 yields Fabs with increased affinity for the lectin. 相似文献