全文获取类型
收费全文 | 37067篇 |
免费 | 2143篇 |
国内免费 | 1182篇 |
专业分类
耳鼻咽喉 | 195篇 |
儿科学 | 651篇 |
妇产科学 | 385篇 |
基础医学 | 5222篇 |
口腔科学 | 608篇 |
临床医学 | 3621篇 |
内科学 | 6936篇 |
皮肤病学 | 447篇 |
神经病学 | 3616篇 |
特种医学 | 974篇 |
外国民族医学 | 4篇 |
外科学 | 2334篇 |
综合类 | 5032篇 |
预防医学 | 1903篇 |
眼科学 | 286篇 |
药学 | 5405篇 |
8篇 | |
中国医学 | 1375篇 |
肿瘤学 | 1390篇 |
出版年
2023年 | 289篇 |
2022年 | 657篇 |
2021年 | 902篇 |
2020年 | 819篇 |
2019年 | 1258篇 |
2018年 | 1233篇 |
2017年 | 985篇 |
2016年 | 853篇 |
2015年 | 914篇 |
2014年 | 1803篇 |
2013年 | 2035篇 |
2012年 | 1741篇 |
2011年 | 1985篇 |
2010年 | 1812篇 |
2009年 | 1725篇 |
2008年 | 1827篇 |
2007年 | 1748篇 |
2006年 | 1561篇 |
2005年 | 1275篇 |
2004年 | 1256篇 |
2003年 | 1211篇 |
2002年 | 1025篇 |
2001年 | 980篇 |
2000年 | 819篇 |
1999年 | 785篇 |
1998年 | 684篇 |
1997年 | 602篇 |
1996年 | 527篇 |
1995年 | 424篇 |
1994年 | 394篇 |
1993年 | 300篇 |
1992年 | 260篇 |
1991年 | 238篇 |
1990年 | 222篇 |
1989年 | 211篇 |
1988年 | 149篇 |
1986年 | 154篇 |
1985年 | 516篇 |
1984年 | 673篇 |
1983年 | 527篇 |
1982年 | 487篇 |
1981年 | 467篇 |
1980年 | 371篇 |
1979年 | 337篇 |
1978年 | 243篇 |
1977年 | 179篇 |
1976年 | 207篇 |
1975年 | 193篇 |
1974年 | 156篇 |
1973年 | 150篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
61.
This study examined the axonal transport of substance P-like immunoreactivity (SPLI) and its content in dorsal root ganglion, trigeminal ganglion, stomach and ileum of non-diabetic rats and two groups of rats with streptozotocin-induced diabetes of 9 months duration. One diabetic group received the aldose reductase inhibitor ‘Statil’ throughout the period of study. To reduce morbidity all diabetic animals were given twice-weekly injections of a long-acting insulin which restricted weight loss but did not prevent regular and severe hyperglycaemia. Axonal transport of SPLI was studied by measurement of accumulation at 12 h ligatures on the left sciatic nerve. There were no differences between the 3 groups either in the calculated anterograde and retrograde mean rates of accumulation (ranges 6.0 to 7.6 and 0.38 to 0.72 mm/h respectively) or mobile fractions of SPLI (means from 0.54 to 0.58). There were, however, marked reductions in anterograde and retrograde accumulations of SPLI in the constricted nerves of the ‘untreated’ diabetics (respectively 57 and 33% of controls;P < 0.01 for both). In the ‘Statil’-treated rats these deficits were attenuated (80 and 75% of controls). Diabetes also reduced the SPLI content of unligated sciatic nerve and trigeminal ganglion (65 and 75% of controls). ‘Statil’ prevented the deficit in the ganglion, but not in the nerve. ‘Statil’ treatment prevented themyo-inositol depletion and attenuated the sorbitol and fructose accumulation seen in the sciatic nerves of the untreated diabetic animals suggesting effective inhibition of aldose reductase in this tissue. The total SPLI content of the stomach and 1-cm segments of ileum were unaltered in the diabetic animals but due to the increased weights of these tissues the SPLI content per unit weight was reduced. These changes were unaffected by ‘Statil’. 相似文献
62.
GEORGE STAVROPOULOS KOSTAS KARAGIANNIS PAUL CORDOPATIS DAVID HALLE CHAIM GILON GIORA BAR-AKIVA ZVI SELINGER MICHAEL CHOREV 《Chemical biology & drug design》1991,37(3):180-184
The analogues [Glu(OBzl)11]SP6–11 and [Glu(OBzl)11]SP5–11 of the C-terminal hexapeptide and heptapeptide of Substance P have been synthesized by conventional solution methods. In each analogue the SCH3 group of Met11 is replaced by the COOCH2C6H5 group. The in vitro activity of both analogues has been determined on three biological preparations: guinea pig ileum (GPI), rat vas deferens (RVD), and rat portal vein (RPV). The selectivity for the different receptors has been studied by utilizing atropine-treated guinea pig ileum (GPI + At). The results showed that both analogues are mainly active on GPI through the NK-1 receptor and that both analogues are equipotent to Substance P. 相似文献
63.
Effect of Short-Term Ethanol Feeding on Rat Testes as Assessed by 31P NMR Spectroscopy, 1H NMR Imaging, and Biochemical Methods 总被引:2,自引:0,他引:2
Hassan Farghali Donald S. Williams Judith Gavaler David H. Van Thiel 《Alcoholism, clinical and experimental research》1991,15(6):1018-1023
31P Nuclear magnetic resonance (NMR) spectroscopy and 1H NMR imaging were used to examine the effect of short-term ethanol feeding on the rat testis. Weanling rats were pair-fed for 10 weeks either on ethanol containing liquid diet (36% ethanol of total calories) or a diet in which dextrimaltose was isocalorically substituted for the ethanol of the alcohol-containing diet. In vivo 31P NMR of the testes was used to determine the intratesticular pH and the relative concentrations of various phosphorus-containing metabolites. The integrity of the blood-testes barrier was evaluated using 1H NMR imaging following a gadolinium diethylene tetramine pentaacetic acid derivative (Gd-DTPA) administration as a vascular contrast agent. After the completion of NMR studies, the testis and the liver were freeze-clamped to allow for the assay of their adenosine-5'-triphosphate (ATP) contents. Serum was assayed for its content of aspartate aminotransferase (AST), alanine aminotransferase (ALT), alcohol and testosterone. Ethanol feeding resulted in the following: (a) a reduction in the body weight (p less than 0.05), (b) a reduction in the testicular phosphodiesters (PDE) PDE/ATP ratio (p less than 0.05), (c) an increased change in the testis image intensity difference between pre- and post-iv Gd-DTPA images, (c) a reduction in the testicular and hepatic content of ATP, and (d) increased serum levels of AST and ALT.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
64.
同步记录72例拟诊冠心病患者头胸导联(HC)及常规导联(wilson)心电图(ECG),并与冠脉造影结果对照。结果:HC与Wilson导联ECG对冠心病诊断的敏感性分别为88.9%与81.5%,特异性33.3%与27.8%,准确性75%与68.1%;二组导联对比无明显差异(P>0.05);对右心室梗塞、缺血及左心室后壁缺血.HC导联的敏感性(91.7%)及准确性(94.4%)均显著高于Wilson导联(12.5%、70.8%,P<0.01),并与冠状动脉病变程度呈高度正相关。HC导联优于Wilson导联。 相似文献
65.
目的 了解儿童急性荨麻疹对心脏的影响。方法 对急性荨麻疹患儿593例行常规心电图检查。结果 33例(5.6%)患儿出现心电图异常改变,主要表现为I度房室传导阻滞、室性早搏、T波低平。皮损消失后心电图亦恢复正常。结论 急性荨麻疹患儿可伴有心脏的损害,临床上应予以重视。 相似文献
66.
A. Reinert A. Kaske S. Mense 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》1998,121(2):174-180
The density of substance P (SP)-, calcitonin gene-related peptide (CGRP)- and vasoactive intestinal polypeptide (VIP)-immunoreactive
(ir) nerve endings was quantitatively evaluated in intact and inflamed gastrocnemius-soleus muscle of the rat. In persistently
inflamed muscle (12 days after a single injection of Freund’s adjuvant into the muscle), the density of SP-ir fibres was significantly
increased. CGRP- and VIP-ir fibres displayed an insignificant increase in density. The density of fibres ir for nerve growth
factor (NGF) and for growth-associated protein 43 (GAP-43/B-50), a marker for axonal sprouting, regeneration and synaptic
reorganisation, increased significantly in persistently inflamed muscle. The data are consistent with the established contribution
of NGF on the expression of SP and GAP-43 in afferent neurones under the influence of a persistent inflammation.
Received: 8 September 1997 / Accepted: 12 February 1998 相似文献
67.
Antibody-dependent neutrophil-mediated parasite killing in non-lethal rodent malaria 总被引:1,自引:1,他引:0
S. WAKI 《Parasite immunology》1994,16(11):587-591
The effects of administrating recombinant human granulocyte colony-stimulating factor (rhG-CSF) and passively transferring immune serum on infection with an attenuated variant of Plasmodium berghei XAT (Pb XAT), in severe combined immunodeficiency (SCID) mice were examined. In immune competent (C.B-17) mice, the attenuated parasite infection was inevitably self-resolving and degenerating forms inside erythrocytes appeared, coinciding with the drop in parasitaemia, whereas SCID mice were unable to control parasite growth and all the mice died. Continuous administration with rhG-CSF caused neutrophilic granulocytosis in both SCID and C.B-17 mice. The effect of rhG-CSF on the infection in C.B-17 mice was to suppress the course of the parasitaemia at an early phase whereas it had no effect in SCID mice. When immune serum was transferred on the day of infection, the prepatent period was prolonged two days in both SCID and C.B-17 mice. When administration with rhG-CSF was combined with transfer of immune serum, SCID mice showed four days delay in patency and degenerating parasites were seen during the course of parasitaemia, although the infection was ultimately fatal. C.B-17 mice similarly treated showed a seven day delay in the onset of the patent parasitaemia which was of a lesser magnitude and shorter in duration compared with control mice. On the other hand, when C.B-17 mice were splenectomized three weeks before infection and then treated with rhG-CSF and immune serum, no degenerating parasites were seen during the infection and all mice died with high parasitaemias. These results show that antibody-dependent neutrophil-mediated parasite killing may occur in the spleen of mice infected with P. berghei XAT. 相似文献
68.
本文介绍免疫组化法检测小儿白血病瘤细胞(P-gp)。检测30例小儿白血病细胞膜P-gp,观察其原发耐药性。30例中有8例p-gp阳性,总阳性率26.67%,其中ANLL单项阳性率33.33%,ALL为20%。本组病例耐约性最高的是CML,其次是ANLL,ALL组最低。同时发现MDR阳性者复发率高,MDR阴性者复发率低,多因素分析表明MDER对初诊白血病患者预后及抗癌药物选择有重要意义。目的临床评价MDR采用检测mdr1mRNA或F-gp,本文认为采用简便、快速的免疫组化法检测P-gp在临床上具有较大的实用价值。 相似文献
69.
C De Simone A Misefari V Covelli A B Maffione S Antonaci E Jirillo 《Journal of clinical laboratory analysis》1989,3(6):345-349
The effects of substance P (SP) on Salmonella minnesota R345 (Rb) binding to human peripheral blood lymphocytes (PBL) were evaluated. Two parameters of bacterial cytoadherence were considered, namely the binding lymphocytes (BL) and the number of bound-bacteria/lymphocyte (BB). The results showed that SP inhibits both BL and BB in a significant manner. Furthermore, distribution of Salmonella binding to CD4+ and CD8+ lymphocytes was studied following SP pretreatment of lymphoid cells. This neuropeptide is able to hamper the bacterial cytoadherence to both T-cell subpopulations and, in particular, the inhibitory effect on the T-suppressor/cytotoxic subset was more pronounced. These findings are discussed in terms of SP intervention in the mechanism of host protection against invading microorganisms. 相似文献
70.
Differential effects of substance P on serotonin-modulated spinal nociceptive reflexes 总被引:2,自引:0,他引:2
Recent immunohistochemical studies indicate the presence of a bulbospinal substance P (SP) system, as well as a bulbospinal
serotonin (5-HT) system, involved in spinal pain transmission. Although electrophysiological studies indicate that SP may
modulate the effects of 5-HT on post-synaptic spinal nociceptive neurons, the functional relationship between SP and 5-HT
on “pain behavior” remains obscure. To bridge this gap between mechanism and behavior, the purpose of the present study was
to determine specific postsynaptic behavioral effects of SP and 5-HT on local spinal nociceptive reflexes in spinally transected
animals. Administration of the 5-HT agonists 5-methoxydi-methyltryptamine (5-MeODMT) (0, 0.5, 1.5, 2.0 mg/kg) and quipazine
(0, 5, 10, 20 mg/kg) 2 days after transection significantly expanded the receptive field (RF) areas of three spinal reflexes,
as previously reported. Intrathecal administration of SP alone (0, 0.25, 2.5, 7.5 ng) also resulted in hyperalgesia, indicated
by a significant expansion of the RF areas of all three nociceptive reflexes. However, administration of SP, in animals pretreated
with 5-HT agonists, decreased the 5-HT-induced expansion of RF size. Therefore, SP had opposite effects on spinal nociceptive
reflexes depending on whether or not the animal was pretreated with 5-HT agonists, i.e., hyperalgesia in the absence of 5-HT
agonists, and analgesia in the presence of 5-HT agonists. The two effects of SP on local spinal reflexes may be related to
the anatomical organization of the two spinal SP systems: 1) SP released from primary afferents facilitates nociceptive reflexes,
and 2) SP associated with the descending bulbospinal system interacts with the descending bulbospinal 5-HT system and inhibits
nociceptive reflexes. The present results help explain contradictory literature regarding the effect of SP on spinal nociceptive
reflexes. 相似文献