全文获取类型
收费全文 | 11742篇 |
免费 | 607篇 |
国内免费 | 77篇 |
专业分类
耳鼻咽喉 | 125篇 |
儿科学 | 174篇 |
妇产科学 | 115篇 |
基础医学 | 1574篇 |
口腔科学 | 373篇 |
临床医学 | 701篇 |
内科学 | 3034篇 |
皮肤病学 | 267篇 |
神经病学 | 860篇 |
特种医学 | 460篇 |
外科学 | 2079篇 |
综合类 | 69篇 |
一般理论 | 1篇 |
预防医学 | 265篇 |
眼科学 | 107篇 |
药学 | 716篇 |
中国医学 | 26篇 |
肿瘤学 | 1480篇 |
出版年
2023年 | 96篇 |
2022年 | 162篇 |
2021年 | 332篇 |
2020年 | 154篇 |
2019年 | 249篇 |
2018年 | 296篇 |
2017年 | 230篇 |
2016年 | 303篇 |
2015年 | 298篇 |
2014年 | 398篇 |
2013年 | 440篇 |
2012年 | 681篇 |
2011年 | 759篇 |
2010年 | 431篇 |
2009年 | 409篇 |
2008年 | 620篇 |
2007年 | 710篇 |
2006年 | 656篇 |
2005年 | 679篇 |
2004年 | 619篇 |
2003年 | 575篇 |
2002年 | 584篇 |
2001年 | 197篇 |
2000年 | 189篇 |
1999年 | 204篇 |
1998年 | 147篇 |
1997年 | 146篇 |
1996年 | 103篇 |
1995年 | 107篇 |
1994年 | 61篇 |
1993年 | 75篇 |
1992年 | 156篇 |
1991年 | 137篇 |
1990年 | 156篇 |
1989年 | 105篇 |
1988年 | 106篇 |
1987年 | 124篇 |
1986年 | 119篇 |
1985年 | 98篇 |
1984年 | 52篇 |
1983年 | 60篇 |
1982年 | 24篇 |
1981年 | 28篇 |
1979年 | 55篇 |
1978年 | 29篇 |
1977年 | 23篇 |
1975年 | 22篇 |
1974年 | 24篇 |
1973年 | 23篇 |
1972年 | 22篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Aoi W Naito Y Sakuma K Kuchide M Tokuda H Maoka T Toyokuni S Oka S Yasuhara M Yoshikawa T 《Antioxidants & redox signaling》2003,5(1):139-144
Dietary antioxidants may attenuate oxidative damage from strenuous exercise in various tissues. Beneficial effects of the antioxidant astaxanthin have been demonstrated in vitro, but not yet in vivo. We investigated the effect of dietary supplementation with astaxanthin on oxidative damage induced by strenuous exercise in mouse gastrocnemius and heart. C57BL/6 mice (7 weeks old) were divided into groups: rested control, intense exercise, and exercise with astaxanthin supplementation. After 3 weeks of exercise acclimation, both exercise groups ran on a treadmill at 28 m/min until exhaustion. Exercise-increased 4-hydroxy-2-nonenal-modified protein and 8-hydroxy-2'-deoxyguanosine in gastrocnemius and heart were blunted in the astaxanthin group. Increases in plasma creatine kinase activity, and in myeloperoxidase activity in gastrocnemius and heart, also were lessened by astaxanthin. Astaxanthin showed accumulation in gastrocnemius and heart from the 3 week supplementation. Astaxanthin can attenuate exercise-induced damage in mouse skeletal muscle and heart, including an associated neutrophil infiltration that induces further damage. 相似文献
102.
103.
Kajiya H Okamoto F Fukushima H Okabe K 《Pflügers Archiv : European journal of physiology》2003,445(6):651-658
Although calcitonin is well known to be a potent inhibitor of bone resorption, it remains unknown how it regulates osteoclastic H(+) transport. In this study, we examined the effects of calcitonin on H(+) extrusion in cultured rat resorbing osteoclasts using an intracellular pH (pHi) indicator, BCECF [2'7'-bis-(2-carboxyethyl)- 5-carboxyfluorescein]. Resorbing osteoclasts were identified by their formation of resorbing pits on calcium phosphate-coated quartz coverslips. Both basal pHi and H(+) extrusion activity were significantly higher compared to non-resorbing osteoclasts. Two types of H(+)-extruding systems were identified by pharmacological and immunocytochemical means: a bafilomycin-A(1)-sensitive and an amiloride-sensitive system [H(+) extrusion mediated by a vacuolar type proton pump (V-ATPase) and by a Na(+)/H(+) exchanger (NHE), respectively]. Calcitonin inhibited both H(+) extrusion activities in a dose-dependent manner and this action was mimicked by protein kinase A (PKA) activators, but not by protein kinase C (PKC) activators. Pretreatment with PKA inhibitors completely suppressed calcitonin-induced inhibition, whereas neither PKC inhibitors nor calcium chelators suppressed it. These results indicate that calcitonin inhibits H(+) extrusion generated by V-ATPase and NHE via PKA activation. These inhibitory mechanisms of H(+) transport by calcitonin are important for the regulation of bone resorption. 相似文献
104.
Nobuhiko Okamoto Mashiro Nakayama Chie Narahara Han-suk Kim Masashi Fujioka Isao Imada Tatsuya Arai Soichiro Toda 《Journal of human genetics》1997,42(3):441-444
Summary Mevalonic acidemia is a rare metabolic disorder due to mevalonate kinase deficiency which affects the biosynthesis of cholesterol
and nonsterol isoprenes. We report the first case of Japan. The clinical course is characterized by intrauterine growth retardation,
postnatal growth failure, intractable diarrhea, liver dysfunctions and death at three months of age. Dysmorphic features including
triangular face, protrusion of forehead, hypertelorism, low set ears and micrognathism were noted. High mevalonic acid level
was found by GC/MS. 相似文献
105.
106.
Diverse functions of the p75 neurotrophin receptor 总被引:5,自引:0,他引:5
Yamashita T Fujitani M Hata K Mimura F Yamagishi S 《Anatomical science international / Japanese Association of Anatomists》2005,80(1):37-41
The pan-neurotrophin receptor p75NTR belongs to a large family of receptors, which includes tumor necrosis factor receptors, Fas and approximately 25 other members. The p75NTR is the first receptor to be cloned molecularly. Recent years have seen the emergence of a consensus regarding the signaling pathways activated by p75NTR and its potential biological function, although receptor characterization had not been targeted for some years. We now know that p75NTR has surprisingly diverse effects, ranging from cell death to regulation of axon elongation. This diversity can be explained by the complex formation of p75NTR with other receptors and multiple signaling molecules that interact with the intracellular domain of p75NTR. 相似文献
107.
Kohji Okabe Kenji Kitamura Hirosi Kuriyama 《Pflügers Archiv : European journal of physiology》1987,409(6):561-568
The 4-aminopyridine (4AP) sensitive outward current of enzymatically dispersed single smooth muscle cells of the rabbit main pulmonary artery were investigated using the voltage clamp method. When the cell was exposed to physiological salt solution (PSS) in the bath and high K+ in the pipette no inward current was generated by depolarization of the membrane, but when 4AP was present in the bath or when Cs+ with tetraethylammonium+ (Cs+-TEA+) in the pipette, an inward current was generated. This current was enhanced by Ba2+ or high Ca2+ and was blocked by inorganic or organic Ca2+ channel blockers.The outward current was partly inhibited by the Ca2+ channel blockers, Ca2+-free or Mn2+ containing solution. The residual outward current was blocked by external application of 10 mM 4AP, whereas it was inhibited by half with 100 mM TEA+. To investigate further natures of 4AP sensitive outward current, the following experiments were done in the bath solution containing 2.5 mM Mn2+. The reversal potential of this outward current, estimated from the tail current, remained the same in Na+-deficient solution, but shifted to near the K+-equilibrium potential in Cl– deficient solution. Thus, the main current carrier for the outward current seems to be K+, but Cl– may participate to some extent. The amplitude of the outward current decreased slowly. However, the reversal potential was not changed, suggesting the reduction in amplitude of the outward current was not due to the accumulation of K+ on the outer surface of the membrane. As 4AP inhibited the outward current to a greater extent at lower than higher membrane potential levels, 4AP bound to the channel may be dislodged at higher levels. When pH of the bath solution was modified from 7.3 to 8.0, inhibitory actions of 4AP were enhanced (pKa value of 4AP=9.17). Thus, a non-ionized form of 4AP may act as a channel blocker. We conclude that in smooth muscle cells of the pulmonary artery, lack of an action potential in physiological solution may partly be due to a small inward current as well as a large contribution of the 4AP sensitive outward current. 相似文献
108.
109.
Kazunaga Agematsu Tetsuji Kobata Feng-Chun Yang Takayuki Nakazawa Keitaro Fukushima Masashi Kitahara Tetsuo Mori Kanji Sugita Chikao Morimoto Atsushi Komiyama 《European journal of immunology》1995,25(10):2825-2829
CD27 is a T cell activation antigen expressed on a majority of peripheral blood T cells. CD27 is also expressed on a subpopulation of human B cells, and it is reported that CD27+ B cells secrete both IgG and IgM. CD70, a ligand for CD27, is expressed on activated T and B cells, suggesting an interaction between T and B cells via CD27/CD70 ligation. Here, we analyze B cell immunoglobulin synthesis using a CD70 transfectant and present functional data showing that B cells secrete large amounts of IgG and IgM as a result of the CD27/CD70 interaction. A flow cytometric analysis showed that CD27 expression was increased and CD70 was expressed on tonsillar and peripheral blood B cells after activation with Staphylococcus aureus Cowan strain (SAC) plus interleukin (IL-2). In addition, the proliferation of B cells was enhanced mildly by the addition of CD70 transfectant, and its proliferation was blocked by anti-CD70 mAb. More importantly, the CD70 transfectant enhanced IgG and IgM production by purified B cells greatly in the presence of SAC plus IL-2. The enhancement was completely blocked by the addition of either anti-CD70 mAb or anti-CD27 mAb. Strongly suggesting that the interaction of CD27 with its ligand, CD70, on B cells plays an important role in B cell growth and differentiation to produce IgG and IgM. 相似文献
110.
DNA typing of HLA in the patients with moyamoya disease 总被引:2,自引:0,他引:2
Takuya K. Inoue Kiyonobu Ikezaki Takehiko Sasazuki Takashi Ono Nobuhiro Kamikawaji Toshio Matsushima Masashi Fukui 《Journal of human genetics》1997,42(4):507-515
Summary Moyamoya disease is a clinical entity demonstrating a chronic occlusion of the cerebrovascular system. Although some possible
etiological factors have been postulated, the etiology of this disease is still unknown. So far, some investigations have
suggested the association between moyamoya disease and HLA in the serological typing. However, DNA typing of HLA have not
been performed yet. Thus, we performed DNA-typing of HLA in the unrelated Japanese patients with definite moyamoya disease,
using the polymerase chain reaction-sequence specific oligonucleotide probe (PCR-SSOP) technique. In the total patients,DQB1*0502 had a positive association with the disease. On the other hand,DRB1*0405 andDQB1*0401 showed a negative association. In comparing the early-onset and late-onset groups, two groups did not share the same disease
associated alleles at all. Thus, the etiology of moyamoya disease seem to have a genetic background. Furthermore, different
genetic factors might also be involved in the difference between the early-onset and late-onset groups. 相似文献