全文获取类型
收费全文 | 22108篇 |
免费 | 1350篇 |
国内免费 | 707篇 |
专业分类
耳鼻咽喉 | 565篇 |
儿科学 | 377篇 |
妇产科学 | 247篇 |
基础医学 | 3279篇 |
口腔科学 | 768篇 |
临床医学 | 1444篇 |
内科学 | 2771篇 |
皮肤病学 | 314篇 |
神经病学 | 2953篇 |
特种医学 | 367篇 |
外国民族医学 | 2篇 |
外科学 | 2162篇 |
综合类 | 2682篇 |
现状与发展 | 1篇 |
预防医学 | 801篇 |
眼科学 | 1828篇 |
药学 | 2382篇 |
7篇 | |
中国医学 | 678篇 |
肿瘤学 | 537篇 |
出版年
2024年 | 49篇 |
2023年 | 273篇 |
2022年 | 548篇 |
2021年 | 806篇 |
2020年 | 596篇 |
2019年 | 542篇 |
2018年 | 565篇 |
2017年 | 529篇 |
2016年 | 530篇 |
2015年 | 635篇 |
2014年 | 959篇 |
2013年 | 1228篇 |
2012年 | 998篇 |
2011年 | 1066篇 |
2010年 | 1067篇 |
2009年 | 1041篇 |
2008年 | 1082篇 |
2007年 | 999篇 |
2006年 | 926篇 |
2005年 | 923篇 |
2004年 | 808篇 |
2003年 | 698篇 |
2002年 | 603篇 |
2001年 | 567篇 |
2000年 | 433篇 |
1999年 | 467篇 |
1998年 | 455篇 |
1997年 | 440篇 |
1996年 | 372篇 |
1995年 | 315篇 |
1994年 | 305篇 |
1993年 | 256篇 |
1992年 | 273篇 |
1991年 | 235篇 |
1990年 | 227篇 |
1989年 | 220篇 |
1988年 | 184篇 |
1987年 | 180篇 |
1986年 | 183篇 |
1985年 | 277篇 |
1984年 | 232篇 |
1983年 | 169篇 |
1982年 | 222篇 |
1981年 | 179篇 |
1980年 | 158篇 |
1979年 | 95篇 |
1978年 | 77篇 |
1977年 | 59篇 |
1976年 | 44篇 |
1975年 | 20篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
目的:探讨保留甲状软骨膜对全喉切除手术进程和病人术后恢复情况的影响。方法:在甲状软骨膜下游离甲状软骨并切断其上角。不结扎和切断舌骨下肌群和喉上动脉。保留之甲状软骨膜用以加强修复咽壁黏膜。结果:本组病例较经典全喉切除术手术时间缩短30min以上。手术中出血在100ml以下。患者术后第2d下床活动,第4d开始进食流质。手术创口均一期愈合。结论:全喉切除术中保留甲状软骨膜可有效地简化手术步骤,减少创伤和出血。利用甲状软骨膜加强咽壁黏膜缝合口,进一步减少了咽漏的发生. 相似文献
92.
Natural killer/T-cell lymphoma (NKTL) and peripheral T-cell lymphomas (PTCL) are prevalent in the Asian population and exhibit a high association with the Epstein-Barr virus (EBV). Moreover, differentiation of these two groups is often difficult and problematic. We investigated 35 cases of NKTL (22 nasal cases and 13 extranasal cases) and 30 cases of PTCL in terms of their clinical features, immunohistology, EBV positivity, EBV strain-type polymorphism and latent membrane protein 1 (LMP1) deletion variant distribution. Eighteen cases (82%) of nasal NKTL and seven (54%) of extranasal NKTL showed EBV positivity by EBV in situ hybridization. Fifteen cases (50%) of PTCL revealed EBV positivity. EBV strain type A was predominant in NKTL (18:5), and EBV strain types A and B were distributed evenly in PTCL (6:6). EBV-positive patients had significantly shorter survival than EBV-negative patients (P < 0.05), and EBV positivity correlated with advanced clinical stage (P < 0.05). Patients harboring type A EBV showed slightly poorer prognoses than those having type B, though it was not obviously statistically different (P = 0.07). The LMP1 deletion variant was prevalent in both NKTL (three wild-type LMP1, 15 deletion variants) and PTCL (three wild-type LMP1, eight deletion variants, two coexistent forms) patients, but did not have prognostic impact. Our results indicate that EBV acts as a negative prognostic factor in NKTL and PTCL, and that the intrinsic properties of a specific viral strain might influence the clinical behavior of these diseases. 相似文献
93.
Summary A simple organ culture method for culturing embryonic skin was developed. A piece of skin with a part of the neural tube from mouse embryo (11 to 12 d) was placed on a 25 mm d membrane filter. The filter was folded to wrap the explant and inserted into glass tubing. The explant and filter in the glass tubing were placed in a rotating tissue culture tube containing 5 ml culture medium (Ham's F12 supplemented with 15 to 20% fetal bovine serum) and filled with a mixture of 95% air:5% CO2. In explants cultured for 6 d fully differentiated melanocytes were observed in the epidermis. 相似文献
94.
Jun Nakayama Kiyohiko Angata Edgar Ong Tsutomu Katsuyama Minoru Fukuda 《Pathology international》1998,48(9):665-677
Polysialic acid is a developmentally regulated carbohydrate composed of a linear homopolymer of a-2,a-linked sialic acid residues. This unique glycan is mainly attached to the neural cell adhesion molecule (N-CAM) and implicated in many morphogenic events of the neural cells by modulating the adhesive property of N-CAM. Recently, the cDNA that encodes polysialyltransferase, which is responsible for the polysialylation of N-CAM, was successfully cloned from three mammalian species. This review focuses on the molecular cloning of human polysialyltransferase, designated PST. it then describes the number of enzymes actually required for the polysialylation of N-CAM using an in vitro polysialyltransferase assay. Comparisons between PST and another polysialyltransferase, sialyltransferase X (STX), are made and it Is demonstrated that both enzymes can independently form polysiatic acid In vitro , but that during neural development they coordinately but distinctly synthesize polysialic acid on N-CAM. The role of polysialic acid in the central nervous system is also discussed. Finally, evidence that the two polysialyltransferases, PST and STX, apparently have distinct roles in the development of neural cells is provided by using a neurite outgrowth assay. 相似文献
95.
Ishitsuka R Kobayashi T 《Anatomical science international / Japanese Association of Anatomists》2004,79(4):184-190
Sphingomyelin is a major sphingolipid species in animal cells and is a major lipid constituent of plasma membranes. Recent reports have established important roles for sphingomyelin and its metabolites as second messengers in signal transduction events during development and differentiation. Sphingomyelin is also a major component of sphingolipid, cholesterol-rich plasma membrane microdomains, known as 'lipid rafts'. However, little is known about the organization of sphingomyelin in biological membranes. Lysenin is a recently discovered sphingomyelin-specific toxin. In the present review, we summarize the current characterization of this protein and describe our recent attempt to elucidate the organization of sphingomyelin in cellular membranes using lysenin as a unique tool. 相似文献
96.
V. V. Teplova V. P. Zinchenko Yu. V. Evtodienko 《Bulletin of experimental biology and medicine》1977,84(2):1159-1162
The pattern of Ca2+ accumulation by tumor mitochondria (MC) was investigated under various experimental conditions. In the absence of penetrating anions tumor MC were shown to take up Ca2+ in only one fifth the amount taken up by liver MC. In the presence of acetate this difference was greater still. Inorganic phosphate (Pin) abolished the observed defects of Ca2+ transport and increased the Ca2+ capacity of the tumor MC considerably. By contrast with liver MC, Pin also had a stabilizing effect on membrane permeability of the tumor MC; this may be the cause of the increasee Ca2+ capacity of these MC.Department of Bioenergetics, Institute of Biological Physics, Academy of Sciences of the USSR, Pushchino-on-Oka. (Presented by Academician of the Academy of Medical Sciences of the USSR S. E. Severin.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 84, No. 8, pp. 202–205, August, 1977. 相似文献
97.
M. V. Sitkovskii S. V. Shestakova Yu. P. Kozlov 《Bulletin of experimental biology and medicine》1979,88(1):777-780
Mitogenic signals from concanavalin A and phytohemagglutinin were shown to undergo summation in time under conditions when each mitogen separately, if the duration of contact with lymphocytes during the experiment was the same (14 or 20 h), did not induce mitogenesis. The results are discussed from the standpoint of cell-cell interaction between lymphocytes. It is suggested that the ability of these signals to undergo time summation lies at the basis of the nonspecific mechanism of protection against tolerance.Laboratory of Physical Chemistry of Biological Membranes, Biological Faculty, M. V. Lomonosov Moscow University. (Presented by Academician of the Academy of Medical Sciences of the USSR V. N. Orekhovich.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 88, No. 7, pp. 89–91, July, 1979. 相似文献
98.
Acute experiments on anesthetized and immobilized cats using intracellular recording were used to study the responses of neurons
in the parietal associative cortex to stimulation of the red nucleus. Efferent neurons of the parietal cortex were identified
by antidromal activation on stimulation of the intrinsic nuclei of the pons and motor cortex. Oligo- and polysynaptic EPSP
in response to stimulation of the red nucleus were seen. The results are discussed in the light of the morphological organization
of the rubrothalamic and cerebellothalamocortical tracts.
Laboratory for Central Nervous System Physiology (Director V. V. Fanardzhyan), L. A. Orbel' Institute of Physiology, Armenian
National Academy of Sciences, Erevan. Translated from Fiziologicheskii Zhurnal imeni I. M. Sechenova, Vol. 81, No. 12, pp.
64–69, December, 1995. 相似文献
99.
Cyclosporin A in the prevention and treatment of experimental autoimmune glomerulonephritis in the brown Norway rat. 总被引:2,自引:1,他引:2
Experimental autoimmune glomerulonephritis (EAG) was induced in brown Norway (BN) rats by a single i.m. injection of collagenase-solubilized homologous glomerular basement membrane (GBM) in Freund's complete adjuvant. This model of anti-GBM disease is characterized by the development, over several weeks, of circulating and deposited anti-GBM antibodies, accompanied by albuminuria. We examined the effects of treatment with oral cyclosporin A (CsA) at different doses, starting at the time of immunization and during the course of the disease. Pretreatment with CsA 5 mg kg daily produced a moderate reduction in circulating anti-GBM antibody levels, reduced deposition of antibody on the GBM and decreased albuminuria. Doses of 10 and 20 mg/kg CsA produced a marked reduction in circulating antibody, absence of detectable deposited antibody and virtual absence of albuminuria. Renal function remained normal in CsA-treated and control animals. When CsA treatment was introduced at 2 or 4 weeks after immunization, there were significant effects on the subsequent autoimmune response and albuminuria at 10 and 20 mg/kg daily. These studies demonstrate that CsA in conventional doses has a therapeutic effect in this model of anti-GBM disease, and suggest a role for T lymphocytes in the pathogenesis of EAG. 相似文献
100.
Heinz Gögelein Eberhard Schlatter Rainer Greger 《Pflügers Archiv : European journal of physiology》1987,409(1-2):122-125
Besides the larger Cl– channel with a single channel conductance of about 45 pS, a small channel was observed in the luminal membrane of the dogfish rectal gland [9]. In cell excised (inside out) patches with NaCl solution on both sides, the latter channel had a single channel conductance of 11±1 pS (n=21), and its current-voltage relationship was linear in the voltage range+90 to –90 mV. The open state probability increased moderately with negative clamp potentials. Ionic replacement studies revealed a high selectivity of Cl– over gluconate, sulfate, and iodide, whereas bromide was permeable to some extent. Also the channel is impermeable for Na+. The Cl– channel blocker 5-nitro-2-(3-phenylpropylamino)-benzoate did not affect this small conductance Cl– channel. It can be concluded that the luminal membrane of stimulated rectal gland cells possesses two types of Cl– channels, which differ markedly in their characteristics.Supported by Deutsche Forschungsgemeinschaft Gr 480/8 and by NSF and NIH grants to the MDIBL 相似文献