全文获取类型
收费全文 | 12621篇 |
免费 | 1131篇 |
国内免费 | 399篇 |
专业分类
耳鼻咽喉 | 43篇 |
儿科学 | 113篇 |
妇产科学 | 59篇 |
基础医学 | 1457篇 |
口腔科学 | 322篇 |
临床医学 | 1005篇 |
内科学 | 1488篇 |
皮肤病学 | 129篇 |
神经病学 | 610篇 |
特种医学 | 455篇 |
外科学 | 573篇 |
综合类 | 1737篇 |
一般理论 | 1篇 |
预防医学 | 2073篇 |
眼科学 | 107篇 |
药学 | 2687篇 |
4篇 | |
中国医学 | 825篇 |
肿瘤学 | 463篇 |
出版年
2024年 | 21篇 |
2023年 | 157篇 |
2022年 | 269篇 |
2021年 | 605篇 |
2020年 | 454篇 |
2019年 | 417篇 |
2018年 | 414篇 |
2017年 | 459篇 |
2016年 | 504篇 |
2015年 | 504篇 |
2014年 | 812篇 |
2013年 | 1028篇 |
2012年 | 725篇 |
2011年 | 816篇 |
2010年 | 628篇 |
2009年 | 591篇 |
2008年 | 542篇 |
2007年 | 501篇 |
2006年 | 475篇 |
2005年 | 393篇 |
2004年 | 351篇 |
2003年 | 354篇 |
2002年 | 286篇 |
2001年 | 227篇 |
2000年 | 188篇 |
1999年 | 205篇 |
1998年 | 178篇 |
1997年 | 180篇 |
1996年 | 154篇 |
1995年 | 142篇 |
1994年 | 136篇 |
1993年 | 116篇 |
1992年 | 125篇 |
1991年 | 105篇 |
1990年 | 101篇 |
1989年 | 108篇 |
1988年 | 97篇 |
1987年 | 80篇 |
1986年 | 80篇 |
1985年 | 95篇 |
1984年 | 78篇 |
1983年 | 60篇 |
1982年 | 65篇 |
1981年 | 49篇 |
1980年 | 48篇 |
1979年 | 52篇 |
1978年 | 39篇 |
1977年 | 44篇 |
1976年 | 29篇 |
1975年 | 23篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
81.
目的 研究携带肝细胞生长因子基因的重组质粒(pUDKH)经肌肉注射给药后在大鼠体内的组织分布及其与大鼠基因组DNA的整合情况。
方法 二级Wistar大鼠雌雄各20只,按体重和取样时间的不同随机分为12h、24h、3d、7d、14d、21d的各实验组(给予pUDKH,2.0mg/kg)和注射后3d取样的对照组(给予PBS,200ul/只),依次将各组大鼠摘眼球取血后脱臼处死,按脑、心、肺、胸腺、肝、肠系膜淋巴结(MLN)、脾、肾、生殖腺、左腿肌肉、右腿肌肉的顺序取样。经典酚/氯仿抽提法提取各组织总DNA,应用紫外分光光度计测定其浓度和纯度,PCR方法检测其中的D肌动蛋白基因;巢式PCR检测各组织总DNA中pUDKH的分布情况;ApnL I酶切分离pUDKH分布阳性各组织中的pUDKHDNA和基因组DNA,巢式PCR检测pUDKHDNA与基因组DNA的整合情况。
结果 各组织总DNA浓度与纯度均符合实验需要,并适于采用PCR或巢式PCR方法进行体内组织分布及基因组DNA整合情况检测。巢式PCR检测显示,在各时间点的右腿肌肉与外周血、注射后3和7d的肝脏、3和14d的生殖腺、7d的胸腺、7和14d的MLN与左腿肌肉等组织中pUDKH分布均呈阳性,而在各时间点的脑、心、肺、脾、肾等组织中pUDKH分布均呈阴性。pUDKH分布阳性的各组织中均未检测到pUDKHDNA与基因组DNA的整合。
结论 pUDKH经肌肉注射给药后,在各时间点大鼠体内各组织中呈现不同的分布谱。在pUDKH分布阳性的各组织中,pUDKHDNA与基因组DNA发生随机整合的概率较低。 相似文献
82.
We studied the kinetics of thietazole distribution in the liver, brain, kidneys, spleen, heart, skeletal muscles, lungs, adipose
tissue, and testicles after single and repeated administration of this drug. Single and repeated administration of thietazole
was followed by elimination of this drug from the blood into organs and tissues. After repeated administration, thietazole
was selectively accumulated in the spleen.
__________
Translated from Byulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 145, No. 5, pp. 555–557, May, 2008 相似文献
83.
Room P. Groenewegen H. J. Lohman A. H. M. 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》1984,56(3):488-496
Summary The spatial organization and laminar distribution of projections from the olfactory bulb and the anterior (PPCa) and posterior (PPCp) divisions of the prepiriform cortex to the entorhinal cortex were studied with anterograde (3H-leucine) and retrograde (WGA-HRP) tracing techniques. After 3H-leucine injections into the olfactory bulb transported labeling was seen over the lateral entorhinal area, except its most medial part, and over the rostral part of the medial entorhinal area. The labeling covers exclusively layer Ia. The lateral and medial entorhinal areas are also reached by fibers from the prepiriform cortex. The projection to the medial entorhinal area has not been described previously. Following injections of 3H-leucine into the PPCa transported labeling is present over the entire expanse of the entorhinal cortex and is located over layer Ib with the greatest density in its superficial part. Injections of 3H-leucine into the PPCp give rise to transported labeling over much of the entorhinal cortex. No labeling was found over the most medial parts of the medial subdivision (VMEA) of the lateral entorhinal area and the medial entorhinal area. Labeling occupies layer Ib, especially its middle part, and layers II and III. Both PPCa and PPCp appear to project most heavily to the dorsal (DLEA) and ventral (VLEA) subdivisions of the lateral entorhinal area. From the retrograde experiments it can be inferred that cells of layers II and III of the PPCa project predominantly to the DLEA, whereas those of the PPCp project predominantly to the VLEA. The MEA receives its heaviest projection from layer II of both PPCa and PPCp. In control experiments with 3H-leucine injections into the endopiriform nucleus it was found that this nucleus projects to the entire expanse of the entorhinal cortex. The fibers distribute to all layers with the exception of layer Ia.Abbreviations AI
agranular insular cortex
- AL
lateral nucleus of the amygdala
- BL
basolateral nucleus of the amygdala
- BM
basomedial nucleus of the amygdala
- C
claustrum
- CoA
cortical nucleus of the amygdala
- DLEA
dorsal division of the lateral entorhinal cortex
- END
endopiriform nucleus
- H
hippocampus
- I
granular insular cortex
- lot
lateral olfactory tractus
- MCL
mitral cell layer of the olfactory bulb
- MEA
medial entorhinal area
- OB
olfactory bulb
- PPCa
anterior part of the prepiriform nucleus
- PPCp
posterior part of the prepiriform nucleus
- VLEA
ventral division of the lateral entorhinal cortex
- VMEA
ventromedial division of the lateral entorhinal cortex
- 35
area 35 of the perirhinal cortex
- 36
area 36 of the perirhinal cortex 相似文献
84.
The effect of temperature and sex on spatial distribution ofDrosophila melanogaster adults was studied in a specially designed apparatus. It was observed that individuals tend to aggregate in sections of the sphere independently of sex and temperature. Nevertheless, decrease in temperature increase aggregation. The mobility of both males and females indicates a megative geotactic tendency. 相似文献
85.
Yasushi Tohi Takashi Nakano Haruyuki Makio Shigekazu Matsui Terunori Fujita Tsutomu Yamaguchi 《Macromolecular chemistry and physics.》2004,205(9):1179-1186
Summary: Bis(phenoxy‐imine) Zr complexes with MAO activation can produce polyethylenes with well‐defined bimodal molecular weight distributions. Polymerization behavior indicates that minor changes in the ligand structures can have a significant effect on the modality of the resulting polyethylenes. Although there is no direct relationship between the bimodal catalytic behavior and the structure of a precatalyst complex in solution, a precatalyst complex having a methyl or methoxy group para to the phenoxy‐oxygen inclined to exhibit bimodal behavior whereas that with a pentafluorophenyl group on the imine‐nitrogen displayed unimodal behavior. Polymerization results suggest that bimodal behavior is linked to the presence of two kinds of cationic active species, which arise from different modes of ligand coordination. A qualitative correlation was found between the calculated amounts of possible cationic active species and the uni‐ and bimodal catalytic behavior. Based on the results obtained, we concluded that the bimodal polyethylenes are produced by two kinds of cationic active species having two available cis‐located sites with cis‐N, trans‐O and cis‐N, cis‐O arrangements. The results introduced herein are rare examples of the production of well‐defined bimodal polyethylenes using a single precatalyst.
86.
细胞外信号调节蛋白激酶(ERK)1/2是重要的信号转导分子。现已知在正常动物的中枢神经系统内有其活化形式即磷酸化的ERK1/2(pERK1/2)分子的存在,但其在小鼠脑内的分布目前还没有全面的观察。本研究用免疫组织化学技术(ABC法)研究了pERK1/2样免疫反应阳性产物在脱臼处死的正常小鼠全脑内的分布。结果发现pERK1/2在正常小鼠脑内有广泛的表达,阳性产物主要存在于神经元,亦见于个别白质内的胶质细胞,脑膜及室管膜细胞也有表达。强阳性表达的核团主要有:岛皮质、视听皮质、边缘前皮质、扣带前皮质、海马垂直部、弓状核、蓝斑和小脑Purkinje细胞;中等阳性表达的核团主要有:感觉运动皮质、外侧隔区、内侧杏仁核、皮质杏仁核和外侧杏仁核、丘脑室旁核前部、视交叉上核、穹隆下器、终板血管器、前腹侧视前核和下丘脑背内侧核;弱阳性表达的核团主要有:视上核、下丘脑室旁核大细胞部、下丘脑后区、顶盖前区、室周灰质腹外侧柱、A5区、孤束核和延髓腹外侧网状结构等。本文结果观察到pERK1/2在正常小鼠脑内广泛存在,提示pERK1/2作为重要的信号转导分子,可能参与许多脑区在正常状态下的功能活动,揭示其分布特点为了解其在脑内的多样性功能提供了形态学依据。 相似文献
87.
Aleksey I. Kovalev Kazuhiko Takeuchi Alexander V. Barzykin Michihiko Asai Mitsuru Ueda Alexander L. Rusanov 《Macromolecular chemistry and physics.》2005,206(20):2112-2121
Summary: The polycondensation of 1‐ethynyl‐2,5‐dihexyl‐4‐iodobenzene in the presence of 1‐ethynyl‐2,5‐dihexyl‐4‐(2‐phenylethynyl)benzene proceeds according to the mechanism of initiated chain growth polycondensation. It has allowed the synthesis of oligomers with a desired molecular weight and a narrow molecular weight distribution. The reasons for the side reaction leading to the formation of diyne compounds are revealed and the presumed mechanism is given. This opens prospects for the preparation of defectless poly(p‐phenyleneethynylene)s with required molecular weights and narrow molecular weight distributions.
88.
Karch R Neumann F Neumann M Szawlowski P Schreiner W 《Annals of biomedical engineering》2003,31(5):548-563
Topological and metric properties of Voronoi polyhedra (VP) generated by the distal end points of terminal segments in arterial tree models grown by the method of constrained constructive optimization (CCO) are analyzed with the aim to characterize the spatial distribution of their supply sites relative to randomly distributed points as a reference model. The distributions of the number N
f
of Voronoi cell faces, cell volume V, surface area S, area A of individual cell faces, and asphericity parameter of the CCO models are all significantly different from the ones of random points, whereas the distributions of V, S, and are also significantly different among CCO models optimized for minimum intravascular volume and minimum segment length (p < 0.0001). The distributions of N
f
, V, and S of the CCO models are reasonably well approximated by two-parameter gamma distributions. We study scaling of intravascular blood volume and arterial cross-sectional area with the volume of supplied tissue, the latter being represented by the VP of the respective terminal segments. We observe scaling exponents from 1.20 ± 0.007 to 1.08 ± 0.005 for intravascular blood volume and 0.77 ± 0.01 for arterial cross-sectional area. Setting terminal flows proportional to the associated VP volumes during tree construction yields a relative dispersion of terminal flows of 37% and a coefficient of skewness of 1.12. © 2003 Biomedical Engineering Society.
PAC2003: 8719Uv, 8710+e, 4720Ky, 0260Pn, 0230Oz 相似文献
89.
N. El bari P. Montagne M. L. Cuilliere G. Humbert G. Linden J. Duheille 《Food and Agricultural Immunology》1992,4(4):229-240
Rabbit anti‐native bovine ß‐casein antiserum reacted with native ß‐casein and fragments f( 1–105/7) and f( 106–209) formed during ß‐casein proteolysis by plasmin. Agglutination of ß‐casein‐coated microparticles by anti‐native ß‐casein antiserum was weakly inhibited by ß‐casein f(1–105/7) and ß‐casein f( 106–209) (0·04 and 1·4%, respectively, compared with native ß‐casein). Immunoreactivity of these ß‐casein peptides in microparticle‐enhanced nephelometric immunoassay was more preserved in the whole ß‐casein than in its isolated fragments. The protein concentration producing 50% inhibition of the ß‐casein‐coated microparticle agglutination with anti‐native ß‐casein antiserum increased during ß‐casein denaturation. A microparticle‐enhanced nephelometric immunoassay, quantifying changes of this inhibiting protein concentration, permitted detection of alteration of the immunoreactivity of ß‐casein during its plasmin proteolysis and heat denaturation, providing an adequate test for the integrity of the whole molecule. 相似文献
90.
《The Knee》2022
BackgroundIn recent years, transcatheter arterial embolization (TAE) using imipenem/cilastatin (IPM/CS) has attracted attention as a treatment for relieving osteoarthritis (OA) pain. However, IPM/CS is not approved by Japanese medical insurance for use as an embolic material. Therefore, it is necessary to develop new embolic materials for TAE to relieve OA pain. The purpose of this study was to develop a swine model of knee arthritis and embolize abnormal neovessels (ANs) using two different embolic materials. We compared the embolic effects and tissue damage in knees.MethodsKnee arthritis was induced by intra-articular injection of papain into 12 knees in six female swine. The swine were divided into two groups of three swine each (six knees per group) for embolization of ANs in the knees with either IPM/CS or soluble gelatin sponge particles (SGSs). Three days after embolization, we compared the embolic effects using angiography and the tissue damage histopathologically.ResultsANs were observed in all 12 knees at 42 days after papain injection. The ANs disappeared and the patent arteries were recanalized 3 days after TAE in all 12 knees. Histopathological evaluation revealed synovitis changes, such as synovial thickening and inflammatory cell infiltration, in all 12 knees. There was no evidence of skin or muscle necrosis in either group. The appearance of ANs, recanalization of the parent arteries, and histopathological outcomes were not significantly different between the two groups.ConclusionSGSs were as safe as IPM/CS for TAE of ANs in this swine model of knee arthritis. 相似文献