全文获取类型
收费全文 | 20466篇 |
免费 | 1062篇 |
国内免费 | 200篇 |
专业分类
耳鼻咽喉 | 152篇 |
儿科学 | 452篇 |
妇产科学 | 177篇 |
基础医学 | 2342篇 |
口腔科学 | 411篇 |
临床医学 | 1188篇 |
内科学 | 6177篇 |
皮肤病学 | 457篇 |
神经病学 | 1373篇 |
特种医学 | 870篇 |
外科学 | 3439篇 |
综合类 | 91篇 |
一般理论 | 3篇 |
预防医学 | 483篇 |
眼科学 | 483篇 |
药学 | 1264篇 |
中国医学 | 40篇 |
肿瘤学 | 2326篇 |
出版年
2023年 | 174篇 |
2022年 | 320篇 |
2021年 | 599篇 |
2020年 | 327篇 |
2019年 | 451篇 |
2018年 | 501篇 |
2017年 | 402篇 |
2016年 | 483篇 |
2015年 | 515篇 |
2014年 | 674篇 |
2013年 | 787篇 |
2012年 | 1349篇 |
2011年 | 1495篇 |
2010年 | 889篇 |
2009年 | 675篇 |
2008年 | 1154篇 |
2007年 | 1297篇 |
2006年 | 1230篇 |
2005年 | 1218篇 |
2004年 | 1135篇 |
2003年 | 1067篇 |
2002年 | 1090篇 |
2001年 | 297篇 |
2000年 | 277篇 |
1999年 | 326篇 |
1998年 | 244篇 |
1997年 | 209篇 |
1996年 | 188篇 |
1995年 | 154篇 |
1994年 | 139篇 |
1993年 | 129篇 |
1992年 | 190篇 |
1991年 | 180篇 |
1990年 | 164篇 |
1989年 | 193篇 |
1988年 | 144篇 |
1987年 | 144篇 |
1986年 | 123篇 |
1985年 | 119篇 |
1984年 | 84篇 |
1983年 | 62篇 |
1982年 | 40篇 |
1981年 | 36篇 |
1980年 | 43篇 |
1979年 | 53篇 |
1978年 | 32篇 |
1977年 | 33篇 |
1974年 | 25篇 |
1971年 | 30篇 |
1968年 | 27篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
41.
The excitatory and inhibitory modulation of primary afferent fibre-evoked responses of ventral roots in the neonatal rat spinal cord exerted by nitric oxide. 总被引:5,自引:2,他引:3
下载免费PDF全文
![点击此处可从《British journal of pharmacology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
1. We investigated the role of nitric oxide (NO) in modulating spinal synaptic responses evoked by electrical and noxious sensory stimuli in the neonatal rat spinal cord in vitro. 2. Potentials were recorded extracellularly from a ventral root (L3-L5) of the isolated spinal cord preparation or spinal cord-saphenous nerve-skin preparation of 0- to 2-day-old rats. Spinal reflexes were elicited by electrical stimulation of the ipsilateral dorsal root or by noxious skin stimulation. 3. In the spinal cord preparation, single shock stimulation of a dorsal root at C-fibre strength induced mono-synaptic reflex followed by a slow depolarizing response lasting about 30 s (slow ventral root potential; slow VRP) in the ipsilateral ventral root of the same segment. Bath-application of NO gas-containing medium (10(-4)- 10(-2) dilution of saturated medium) and NO donors, 1-hydroxy-2-oxo-3-(N-ethyl-2-aminoethyl)-3-ethyl-1-triazene (NOC12, 3-300 microM), S-nitroso-N-acetyl-D,L-penicillamine (SNAP, 3-300 microM) and S-nitroso-L-glutathione (GSNO, 3-300 microM), produced an inhibition of the slow VRP and a depolarization of ventral roots. Another NO donor, 3-morpholinosydononimine (SIN-1, 30-300 microM), also depressed the slow VRP but did not depolarize ventral roots. These agents did not affect the mono-synaptic reflex. 4. In the spinal cord-saphenous nerve-skin preparation, application of capsaicin (0.1-0.2 microM) to skin evoked a slow depolarizing response of the L3 ventral root. This slow VRP was depressed by NOC12 (10-300 microM) and SIN-1 (100-300 microM). When the concentration of NOC12 was increased to 1 mM, spontaneous synaptic activities were augmented and the depressant effect of NOC12 on the slow VRP became less pronounced. 5. A NO-scavenger, 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide( carboxy- PTIO, 100-300 microM) prevented the depressant effect on the dorsal root-evoked slow VRP and ventral root depolarizing effects of NO donors. Carboxy-PTIO increased spontaneous synaptic activities and markedly potentiated the slow VRP. A NO synthase (NOS) inhibitor, N omega-nitro-L-arginine methyl ester (L-NAME, 0.03-1 microM), but not D-NAME (0.03-1 microM), also markedly potentiated the slow VRP and this effect was reversed by L-arginine (300 microM). 6. 8-Bromo-cyclic guanosine 3': 5'-monophosphate (8-Br-cyclic GMP, 100-300 microM) produced both an inhibition of the slow VRP and a depolarization of ventral roots. A cyclic GMP-dependent protein kinase inhibitor, KT5823 (0.3 microM), partly inhibited the depressant effects of NO donors and 8-Br-cyclic GMP on the dorsal root-evoked slow VRP. In contrast, KT5823 did not inhibit the depolarizing effects of NO donors. 7. Perfusion of the spinal cord with medium containing tetrodotoxin (0.3 microM) and/or low Ca2+ (0.1 mM)-high Mg2+ (10 mM) markedly potentiated the depolarizing effect of NO donors. The SNAP-evoked depolarization in the tetrodotoxin-containing low Ca(2+)-high Mg2+ medium was significantly inhibited by excitatory amino acid receptor antagonists D-(-)-2-amino-5-phosphonovaleric acid (30 microM) and 6-cyano-7-nitroquinoxaline-2,3-dione (10 microM). 8. The present study suggests that inhibitory and excitatory mechanisms meditated by the NO-cyclic GMP cascade are involved in the primary afferent fibre-evoked nociceptive transmission in the neonatal rat spinal cord. The inhibitory mechanism, but not the excitatory mechanism, appears to be partly mediated by cyclic GMP-dependent protein kinase. It is also suggested that Ca(2+)-independent release of excitatory amino acid neurotransmitters contributes to the depolarizing response to NO of ventral roots. 相似文献
42.
目的:比较正常肝组织与肝癌AH 109A,吉田肉瘤中谷氨酸脱氢酶,胆碱氧化酶和葡萄糖-6-磷酸酶的活力对~(67)Ga摄取与积累的影响;方法:制备~(67)Ga枸橼酸溶液给大鼠静注后处死大鼠,制备亚细胞悬液,液闪计数器测定放射活度.结果:~(67)Ga的放射活性在正常肝组织溶酶体中(55%积聚)显著高于肝癌AH109A(32%积聚)和吉田肉瘤(18%)积聚.谷氨酸脱氢酶的活力在正常肝组织,肝癌和吉田肉瘤分别是1830±s 320 U·L~(-1),23±s 6 U·L~(-1)和7±s 2 U·L~(-1);胆碱氧化酶的活力分别是46±s 10 U·L~(-1),25.0±s 0.4 U·L~(-1),2.0±0.4 U·L~(-1);葡萄糖-6-磷酸酶活力分别是2550±s 180 U·L~(-1),84±s 14 U·L~(-1),78±s13 U·L~(-1).结论:正常肝组织中溶酶体酶活力很强,对~(67)Ga的积累起较大作用.癌变组织酶活力降低而作用减弱.吉田肉瘤细胞无肝细胞特点,其溶酶体对~(67)Ga积累作用不大. 相似文献
43.
Tetsumori Yamashima Takaomi C. Saido Masatoshi Takita Atsuo Miyazawa Jun Yamano Atsuo Miyakawa Hisashi Nishijyo Junkoh Yamashita Seiichi Kawashima Taketoshi Ono Tohru Yoshioka 《The European journal of neuroscience》1996,8(9):1932-1944
To clarify the mechanism of postischaemic delayed cornu Ammonis (CA)-1 neuronal death, we studied correlations among calpain activation and its subcellular localization, the immunoreactivity of phosphatidylinositol 4,5-bisphosphate (PIP2) and Ca2+ mobilization in the monkey hippocampus by two independent experimental approaches: in vivo transient brain ischaemia and in vitro hypoxia-hypoglycaemia of hippocampal acute slices. The CA-1 sector undergoing 20 min of ischaemia in vivo showed microscopically a small number of neuronal deaths on day 1 and almost global neuronal loss on day 5 after ischaemia. Immediately after ischaemia, CA-1 neurons ultrastructurally showed vacuolation and/or disruption of the lysosomes. Western blotting using antibodies against inactivated or activated μ-calpain demonstrated μ-calpain activation specifically in the CA-1 sector immediately after ischaemia. This finding was confirmed in the perikarya of CA-1 neurons by immunohistochemistry. CA-1 neurons on day 1 showed sustained activation of μ-calpain, and increased immunostaining for inactivated and activated forms of μ- and m-calpains and for PIP2. Activated μ-calpain and PIP2 were found to be localized at the vacuolated lysosomal membrane or endoplasmic reticulum and mitochondrial membrane respectively, by immunoelectron microscopy. Calcium imaging data using hippocampal acute slices showed that hypoxia-hypoglycaemia in vitro provoked intense Ca2+ mobilization with increased PIP2 immunostaining specifically in CA-1 neurons. These data suggest that transient brain ischaemia increases intracellular Ca2+ and PIP2 breakdown, which will activate calpain proteolytic activity. Therefore, we suggest that activated calpain at the lysosomal membrane, with the possible release of biodegrading enzyme, will cause postischaemic CA-1 neuronal death. 相似文献
44.
N Shinoura T Kondo I Muraoka Y Tsukamoto M Yoshioka H Miyazawa 《No shinkei geka. Neurological surgery》1990,18(6):557-561
Two cases of sacrococcygeal teratoma in female infants are reported. Case 1. A newborn baby with a hemispheric mass on her hip underwent surgery 3 days after birth and the lesion proved to be an immature teratoma. The serum AFP level was very high but became normal one month after the operation. The child also had agenesis of the corpus callosum and arachnoid cysts in right middle fossa. She died after developing shunt infection. Case 2. A newborn baby with a mature teratoma was operated on the day following birth. The tumor was subtotally removed, and there has been no recurrence after 6 months. Sacrococcygeal teratoma in female infants is often associated with agenesis of the corpus callosum and arachnoid cysts. They tend to develop almost at the same time as the teratoma. It is often difficult to determine whether the infant should be treated by chemotherapy or not if the teratoma is immature, especially when it has been totally removed, the serum AFP is normal, and the tumor is pathologically of a low grade. 相似文献
45.
Shuji Kurane MD Marjorie T. Arca MD Atsushi Aruga MD PhD Robert A. Krinock BS John C. Krauss MD Dr. Alfred E. Chang MD 《Annals of surgical oncology》1997,4(7):579-585
Background: We examined alternative methods of delivering cytokines as an adjunct for priming lymph node (LN) cells draining sites of vaccine inoculation for the purpose of generating immune cells for adoptive immunotherapy.
Methods: Using syngeneic murine tumors we examined the ability of IL-2, IL-4, or GM-CSF delivered locally to a site of tumor inoculum to induce antitumor reactive draining LN cells. Mice were inoculated subcutaneously with tumor cells transduced to secrete cytokine; tumor cells admixed with fibroblasts transduced to secrete cytokine; or intralesional inoculation of cytokine in established tumor to induce sensitized LN cells capable of mediating tumor regression in adoptive transfer.
Results: Both IL-4 and GM-CSF cytokines were effective in enhancing the antitumor reactivity of vaccine-primed LN cells compared to IL-2, which was ineffective. The local delivery of GM-CSF by autocrine or paracrine secretion of genetically engineered cells, as well as direct intratumoral delivery was capable of upregulating LN sensitization compared to systemic administration, which did not.
Conclusions: The local delivery of GM-CSF as an adjuvant for tumor vaccination can be accomplished by various methods, including direct injection, which avoids the need for gene transfer. 相似文献
46.
Takeda Atsushi Kikuchi Akio Matsuzaki-Kobayashi Michiko Sugeno Naoto Itoyama Yasuto 《Journal of neurology》2007,254(4):IV2-IV7
Journal of Neurology - Olfactory dysfunction in Parkinson's disease (PD) has been described for more than thirty years and known as one of the commonest non-motor symptoms in PD. Recently, it... 相似文献
47.
A 71-year-old man with left periorbital pain and diplopia was hospitalized for evaluation and treatment. He had a past history of untreated diabetes mellitus. Shortly after admission, the patient experienced rapid onset of visual loss in the left eye. MRI and CT showed a lesion expanding from the left orbital apex to the left pterygopalatine fossa. Invasive aspergillosis was diagnosed by open biopsy of intrasinus mucosa via the left maxillary sinus. The patient was treated with voriconazole, an antifungal agent, and marked improvements in left periorbital pain and eye movement were subsequently obtained, although visual acuity was not recovered. This is the first report documenting the clinical utility of voriconazole for sino-orbital invasive aspergillosis. 相似文献
48.
Disrupted-In-Schizophrenia-1 (DISC1) is a promising candidate gene for schizophrenia (SZ) and bipolar disorder (BP), but its basic biology remains to be elucidated. Accumulating genetic evidence supports that DISC1 is associated with some aspects of cognitive functions relevant to SZ and BP. Here, we provide a summary of the current updates in biological studies of DISC1. Disrupted-In-Schizophrenia-1, preferentially expressed in the forebrain, has multiple isoforms with potential posttranslational modifications. Disrupted-In-Schizophrenia-1 protein occurs in multiple subcellular compartments, which include the centrosome, microtubule fractions, postsynaptic densities, actin cytoskeletal fractions, the mitochondria, and the nucleus. Recent studies have clarified that DISC1 mediates at least centrosome-dynein cascade and cyclic adenosine monophosphate (cAMP) signaling. Furthermore, both cytogenetic and cell biological studies consistently suggest that an overall loss of DISC1 function (either haploinsufficiency or dominant-negative, or both) may be associated with SZ and BP. On the basis of these findings, production of DISC1 genetically engineered mice is proposed as a promising animal model for SZ and BP. Several groups are currently generating DISC1 mice and starting to characterize them. In this review, the advantages and disadvantages of each animal model are discussed. 相似文献
49.
50.
在免眼中进行经瞳孔阈值下温热疗法的组织学效应和蛋白表达 总被引:1,自引:0,他引:1
Yoshihiro Morimura Annabelle A. Okada Atsushi Hayashi Sayuri Fujioka Sumie Kawahara Tetsuo Hida 李扬 《美国医学会眼科杂志(中文版)》2005,17(3):185-186
目的:研究阈值下经瞳孔温热疗法(TTT)对视网膜组织学的效应。方法:对正常视网膜色素的兔眼进行TTT,通过1个810nm激光二极管产生直径为1.2mm能量为50mW的光斑,持续时间为15、30和60秒。4周后进行荧光血管造影并摘除眼球,通过电子显微镜和免疫组化染色来检查。 相似文献