全文获取类型
收费全文 | 3954篇 |
免费 | 517篇 |
国内免费 | 21篇 |
专业分类
耳鼻咽喉 | 68篇 |
儿科学 | 90篇 |
妇产科学 | 216篇 |
基础医学 | 568篇 |
口腔科学 | 65篇 |
临床医学 | 511篇 |
内科学 | 1067篇 |
皮肤病学 | 62篇 |
神经病学 | 328篇 |
特种医学 | 108篇 |
外科学 | 429篇 |
综合类 | 54篇 |
预防医学 | 171篇 |
眼科学 | 63篇 |
药学 | 352篇 |
中国医学 | 35篇 |
肿瘤学 | 305篇 |
出版年
2023年 | 28篇 |
2022年 | 73篇 |
2021年 | 131篇 |
2020年 | 96篇 |
2019年 | 154篇 |
2018年 | 147篇 |
2017年 | 126篇 |
2016年 | 156篇 |
2015年 | 165篇 |
2014年 | 168篇 |
2013年 | 247篇 |
2012年 | 278篇 |
2011年 | 243篇 |
2010年 | 207篇 |
2009年 | 163篇 |
2008年 | 224篇 |
2007年 | 205篇 |
2006年 | 198篇 |
2005年 | 183篇 |
2004年 | 157篇 |
2003年 | 124篇 |
2002年 | 123篇 |
2001年 | 92篇 |
2000年 | 101篇 |
1999年 | 86篇 |
1998年 | 26篇 |
1997年 | 27篇 |
1996年 | 23篇 |
1995年 | 20篇 |
1994年 | 11篇 |
1993年 | 25篇 |
1992年 | 58篇 |
1991年 | 39篇 |
1990年 | 32篇 |
1989年 | 39篇 |
1988年 | 41篇 |
1987年 | 29篇 |
1986年 | 16篇 |
1985年 | 25篇 |
1984年 | 22篇 |
1983年 | 16篇 |
1981年 | 9篇 |
1980年 | 13篇 |
1979年 | 18篇 |
1978年 | 12篇 |
1975年 | 14篇 |
1974年 | 10篇 |
1973年 | 11篇 |
1972年 | 11篇 |
1971年 | 11篇 |
排序方式: 共有4492条查询结果,搜索用时 15 毫秒
41.
42.
43.
44.
45.
46.
Mechanisms underlying the inhibitory effect of propofol on the contraction of canine airway smooth muscle. 总被引:6,自引:0,他引:6
C C Lin M H Shyr P P Tan C S Chien S L Pan C C Wang C T Chiu C M Yang 《Anesthesiology》1999,91(3):750-759
BACKGROUND: Propofol has been shown to produce relaxation of preconstricted airway smooth muscle. Although the inhibition of calcium mobilization is supposed to be the major mechanism of action, the whole picture of the mechanisms is not completely clear. METHODS: Contractile response was performed using canine tracheal rings. The effects of propofol on carbachol-induced mobilization of intracellular Ca2+ and phosphoinositide hydrolysis were measured using cultured canine tracheal smooth muscle cells by monitoring fura-2 signal and assessing the accumulation of [3H]-inositol phosphates. To detect the effect of propofol on muscarinic receptor density and affinity, [3H]N-methyl-scopolamine was used as a radioligand for receptor binding assay. RESULTS: Pretreatment with propofol shifts the concentration-response curves of carbachol-induced smooth muscle contraction to the right in a concentration-dependent manner without changing the maximal response. Propofol not only decreased the release of Ca2+ from internal stores but also inhibited the calcium influx induced by carbachol. In addition, carbachol-induced inositol phosphate accumulation was attenuated by propofol; the inhibitory pattern was similar to the contractile response. Moreover, propofol did not alter the density of muscarinic receptors. The dissociation constant value was not altered by pretreatment with 100 microM propofol but was significantly increased by 300 microM (propofol, 952+/-229 pM; control, 588+/-98 pM; P<0.05). CONCLUSIONS: Propofol attenuates the muscarinic receptor-mediated airway muscle contraction. The mechanism underlying these effects was attenuation of inositol phosphate generation and inhibition of Ca2+ mobilization through the inhibition of the receptor-coupled signal-transduction pathway. 相似文献
47.
Effect of seeding duration on the strength of chondrocyte adhesion to articular cartilage. 总被引:1,自引:0,他引:1
R M Schinagl M S Kurtis K D Ellis S Chien R L Sah 《Journal of orthopaedic research》1999,17(1):121-129
Chondrocyte adhesion to cartilage may play an important role in the repair of articular defects by maintaining cells in positions where their biosynthetic products can contribute to the repair process. The objective of this in vitro study was to determine the effect of the duration of seeding time on the ability of chondrocytes to resist detachment from cartilage when subjected to mechanical perturbation (fluid-induced shear stress). Suspensions of adult bovine articular chondrocytes were prepared from primary, high-density monolayer cultures and infused into a parallel-plate shear-flow chamber where they settled onto 50-microm-thick sections of bovine articular cartilage at a density of approximately 20,000 cells/cm2. The chondrocytes were seeded and allowed to attach to the cartilage surface for specific durations (5-40 minutes) in medium including 10% serum at 22 degrees C, after which the cells were exposed to fluid flow-induced shear stresses (6-90 Pa). The fraction of detached cells at each shear stress was calculated from microscopic images. Shear stress was applied for 1 minute because this length of time was sufficient to induce steady-state cell detachment. Increasing the duration of cell seeding led to a more firm attachment of chondrocytes to cartilage. After 9 minutes of seeding, 50% cell detachment was induced by gravitational force alone. After 40 minutes of seeding, 50% detachment required 26 Pa of shear stress. Extrapolation of the data to account for the effect of repeated applications of cell suspensions to an individual cartilage substrate indicated that for a freshly prepared cartilage section, 50% detachment was induced by gravity after 25 minutes of seeding and by 2.3 Pa of shear stress after 40 minutes of seeding. The increase in resistance to shear stress-induced cell detachment with increasing seeding duration suggests that it may be beneficial to allow chondrocytes to stabilize in the absence of applied load for some time after chondrocyte transplantation for cartilage repair in vivo. 相似文献
48.
Meng‐Lin Liao Wei‐Hau Peng Daphne Kan Chung‐Liang Chien 《The Journal of comparative neurology》2016,524(18):3810-3826
α‐Internexin is a member of the neuronal intermediate filament (nIF) protein family, which also includes peripherin and neurofilament (NF) triplet proteins. Previous studies found that expression of α‐internexin precedes that of the NF triplet proteins in mammals and suggested that α‐internexin plays a key role in the neuronal cytoskeleton network during development. In this study, we aimed to analyze the expression patterns and function of internexin neuronal intermediate filament protein‐alpha a (inaa), the encoding gene of which is a homolog of the mammalian α‐internexin, during retinal development in zebrafish. Via in vitro and in vivo studies, we demonstrated that zebrafish inaa is an α‐internexin homolog that shares characteristics with nIFs. An immunohistochemical analysis of zebrafish revealed that inaa was distributed dynamically in the developing retina. It was widely localized in retinal neuroepithelial cells at 1 day postfertilization (dpf), and was mainly found in the ganglion cell layer (GCL) and inner part of the inner nuclear layer (INL) from 3–9 dpf; after 14 dpf, it was restricted to the outer nuclear layer (ONL). Moreover, we demonstrated for the first time that inaa acted distinctively from the cytoskeletal scaffold of zebrafish cone photoreceptors during development. In conclusion, we demonstrated the morphological features of a novel nIF, inaa, and illustrated its developmental expression pattern in the zebrafish retina. J. Comp. Neurol. 524:3810–3826, 2016. © 2016 Wiley Periodicals, Inc. 相似文献
49.
Tu‐Lai Yew Tung‐Fu Huang Hsiao‐Li Ma Yuan‐Tong Hsu Chih‐Chien Tsai Chao‐Ching Chiang Wei‐Ming Chen Shih‐Chieh Hung 《Journal of orthopaedic research》2012,30(8):1213-1220
To realize the therapeutic potential of mesenchymal stem cells (MSCs), we aimed to develop a method for isolating and expanding New Zealand rabbit MSCs in a great scale. Rabbit MSCs expanded under hypoxic and normoxic conditions were compared in terms of replication capacity, differentiation potential, and the capacity for allogeneic transplantation in a calvarial defect model. The cells from all tested rabbits were expanded more rapidly when plated at low‐density under hypoxic conditions compared to under normoxic conditions. Moreover, cells expanded under hypoxic conditions increased in the potential of osteoblastic, adipocytic, and chondrocytic differentiation. More importantly, radiographic analysis and micro‐CT measurement of bone volume revealed the hypoxic cells when transplanted in the calvarial defects of another rabbit increased in the ability to repair bone defect compared to the normoxic cells. Six weeks after allogeneic transplantation of hypoxic MSCs, histological analysis revealed a callus spanned the length of the defect, and several bone tissues spotted in the implant. At 12 weeks, new bone had formed throughout the implant. Using BrdU labeling to track the transplanted cells, the hypoxic cells were more detected in the newly formed bone compared to the normoxic cells. For defects treated with allogeneic MSCs, no adverse host response could be detected at any time‐point. In conclusion, we have developed a robust method for isolation and expansion of rabbit MSCs by combining low‐density with hypoxic culture, which can be applied for the design of clinical trials in allogeneic transplantation of MSCs for bone healing. © 2012 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 30:1213–1220, 2012 相似文献
50.
Catharina M. L. Zegers Wouter van Elmpt Katrin Szardenings Hartmuth Kolb Alan Waxman Rathan M. Subramaniam Dae Hyuk Moon Jacqueline C. Brunetti Shyam M. Srinivas Philippe Lambin David Chien 《European journal of nuclear medicine and molecular imaging》2015,42(12):1840-1849