全文获取类型
收费全文 | 40843篇 |
免费 | 3216篇 |
国内免费 | 1186篇 |
专业分类
耳鼻咽喉 | 191篇 |
儿科学 | 936篇 |
妇产科学 | 516篇 |
基础医学 | 6369篇 |
口腔科学 | 848篇 |
临床医学 | 2825篇 |
内科学 | 6310篇 |
皮肤病学 | 705篇 |
神经病学 | 3502篇 |
特种医学 | 617篇 |
外国民族医学 | 5篇 |
外科学 | 3227篇 |
综合类 | 5471篇 |
现状与发展 | 4篇 |
预防医学 | 1905篇 |
眼科学 | 492篇 |
药学 | 6308篇 |
4篇 | |
中国医学 | 1970篇 |
肿瘤学 | 3040篇 |
出版年
2024年 | 76篇 |
2023年 | 705篇 |
2022年 | 1651篇 |
2021年 | 1815篇 |
2020年 | 1372篇 |
2019年 | 1541篇 |
2018年 | 1519篇 |
2017年 | 1413篇 |
2016年 | 1283篇 |
2015年 | 1353篇 |
2014年 | 2216篇 |
2013年 | 2445篇 |
2012年 | 2031篇 |
2011年 | 2467篇 |
2010年 | 1951篇 |
2009年 | 1989篇 |
2008年 | 1991篇 |
2007年 | 1770篇 |
2006年 | 1643篇 |
2005年 | 1534篇 |
2004年 | 1442篇 |
2003年 | 1253篇 |
2002年 | 1083篇 |
2001年 | 819篇 |
2000年 | 797篇 |
1999年 | 697篇 |
1998年 | 562篇 |
1997年 | 574篇 |
1996年 | 501篇 |
1995年 | 467篇 |
1994年 | 401篇 |
1993年 | 291篇 |
1992年 | 241篇 |
1991年 | 246篇 |
1990年 | 185篇 |
1989年 | 155篇 |
1988年 | 167篇 |
1987年 | 132篇 |
1986年 | 143篇 |
1985年 | 288篇 |
1984年 | 304篇 |
1983年 | 239篇 |
1982年 | 269篇 |
1981年 | 214篇 |
1980年 | 198篇 |
1979年 | 181篇 |
1978年 | 135篇 |
1977年 | 94篇 |
1976年 | 103篇 |
1975年 | 91篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
221.
An assortment of drugs was injected into one or both ventromedial nuclei of the thalamus, to see how these influenced stereotypy, locomotion and posture in spontaneously behaving and actively rotating rats. Unilateral intrathalamic muscimol promoted weak ipsiversive circling, while bilateral treatment gave catalepsy. Similar injections of 4-amino-hex-5-enoic acid, which inhibits γ-aminobutyrate metabolism, raised γ-aminobutyrate levels in the ventromedial nuclei more than three-fold yet had none of these behavioural effects. The indirectly acting γ-aminobutyrate agonists flurazepam and cis-1,3-aminocyclohexane car☐ylic acid had little effect on posture and locomotion and, like muscimol and 4-amino-hex-5-enoic acid, elicited only very weak stereotypies. Procaine behaved like the γ-aminobutyrate antagonist bicuculline, provoking vigorous locomotor hyperactivity and teeth chattering if given uni- or bilaterally. Pretreatment of one ventromedial nucleus with muscimol or 4-amino-hex-5-enoic acid, and to a lesser extent flurazepam or cis-1,3-aminocyclohexane car☐ylic acid, gave rise to pronounced ipsilateral asymmetries when combined with a large systemic dose of apomorphine. Contraversive rotations were initiated by unilateral stereotaxic injection of muscimol into the substantia nigra pars reticulata, or with apomorphine from the supersensitive striatum in unilaterally 6-hydroxydopamine lesioned rats. Drug treatments in the ipsilateral ventromedial nucleus showed a similar rank order of potency at inhibiting these circling behaviours, seemingly by reducing apomorphine-induced posture and muscimol-induced hypermotility. The suppression of circling by muscimol in these tests was highlighted by introducing the compound into the ventromedial nucleus at the height of circling activity. Both types of circling stimulus lost the capacity to increase locomotion, but still caused head turning and stereotypy in rats made cataleptic with bilateral ventromedial muscimol. Treating one ventromedial thalamus with muscimol greatly intensified any pre-existing posture directed towards that side, and vice versa.
These data suggest that the ventromedial nucleus is not involved with the expression of stereotyped behaviours, but can profoundly influence posture and locomotion, especially in the presence of some other motor stimulus. The recovery of circus movements in rats with impaired ventromedial nucleus function implies this nucleus is not essential for the execution of circling in these models. 相似文献
222.
Joan L. Longbottom Ph.D. 《The Journal of allergy and clinical immunology》1983,72(6):668-675
Sera of patients with ABPA were tested by XRIE tests incorporating their own serum (self-XRIE) to detect the presence of IgG/IgE antigen complexes to a “reference” Aspergillus fumigatus preparation. Of the 32 sera studied, 29 (90%) had visible precipitin (IgG) peaks, and 27 of these 29 as well as the three apparently precipitin-negative sera, i.e., 30 (94%), showed binding of specific IgE by autoradiography. The two precipitin-positive sera that did not show IgE binding were also skin test negative and RAST negative to this A. fumigatus antigen. Specific IgG as determined in ELISA correlated well with the grading of the XIE precipitin peaks (p < 0.05). There was also a highly significant correlation between specific IgE by RAST and grading the radioactive uptake seen in the autoradiograph (p < 0.001) indicating, for each serum, the presence of IgG antibodies to most of the components to which there was specific IgE. In the self-XRIE tests there was considerable variation of reactivity from serum to serum, in numbers of antigen/antibody peaks observed, in relative peak heights, and in the intensity of the respective staining. By comparing each test to a “reference” pattern developed with the use of an ABPA serum pool, the antigenic components of A. fumigatus were found to be of two main types: (1) antigens that appeared to be poorly precipitating (possibly low-molecular-weight components) but showed strong IgE binding (these were apparently major allergenic components and with one exception proved to be the faster migrating components) and (2) antigens that produced the strongest precipitin reactions with only weak binding of specific IgE and therefore minor allergenic components. 相似文献
223.
Robert Norlund Kjell Grankvist Lena Norlund Inge-Bert Täljedal 《Virchows Archiv : an international journal of pathology》1984,404(1):31-38
Summary Stereological techniques on electron microscopy micrographs were used to evaluate the morphological changes of cultured islet cells that had been exposed to alloxan or 6-hydroxydopamine.Trypan Blue exclusion by cells cultured for 3 days indicated that the cells were 100% viable. Electron microscopy revealed that nearly all of the surviving cultured cells were cells.Exposure to 5 mmol/l alloxan or 1–5 mmol/l 6-hydroxydopamine for 10 or 30 min caused a general swelling of the cultured cells with a concomitant swelling of mitochondria and nuclei. The size of the secretory granules was not affected by the drugs. Only 3–10% of the cells excluded Trypan Blue after exposure to 5 mmol/l alloxan or 6-hydroxydopamine.The data conform with the hypothesis that a primary action of alloxan and 6-hydroxydopamine is at the plasma membrane level of cells.Abbreviations and definitions
A
cell
Cell profile area (µm2), surface area of one cell section surface
-
V
n
Nuclear volume density (%), number of points over the nucleus divided by the number of points over the total cell area × 100
-
V
m
Mitochondrial volume density (%), number of points over mitochondria divided by hits over the cytoplasm (points over the cell minus points over the nucleus) × 100
-
V
g
Granular volume density (%), number of points over granules divided by hits over the cytoplasm × 100 相似文献
224.
SARS coronavirus induces apoptosis in Vero E6 cells 总被引:15,自引:0,他引:15
Yan H Xiao G Zhang J Hu Y Yuan F Cole DK Zheng C Gao GF 《Journal of medical virology》2004,73(3):323-331
Severe acute respiratory syndrome (SARS) is an emerging infectious disease. Its etiological agent has been convincingly identified as a new member of family Coronaviridae (SARS-CoV). It causes serious damage to the respiratory system yet the mechanism is not clear. Infection-induced apoptosis or necrosis is suspected but no direct evidence for this yet exists. To date, Vero E6 cells are the only cell line that could be used to replicate the virus with obvious CPE (cytopathic effect) in vitro. It is known for some viruses (including members of family Coronaviridae) that CPE can be caused either by virus-induced apoptosis (active death) or cell necrosis (passive death). In this study, we examined the apoptosis in the SARS-CoV infected Vero E6 cells. Indeed, the results do show that the CPE was induced by apoptosis rather than necrosis, shown by typical DNA fragmentation, through the existence of apoptotic bodies and swollen mitochondria. This observation has some implications for the SARS-CoV pathogenicity: SARS-CoV does induce apoptosis in cell cultures and might have the same effect in vivo, responsible for the severe damage of the respiratory system. 相似文献
225.
A combination of interleukin-6 and its soluble receptor impairs sperm motility: implications in infertility associated with endometriosis 总被引:7,自引:0,他引:7
Yoshida S Harada T Iwabe T Taniguchi F Mitsunari M Yamauchi N Deura I Horie S Terakawa N 《Human reproduction (Oxford, England)》2004,19(8):1821-1825
BACKGROUND: We previously reported that the level of interleukin (IL)-6 is increased in the peritoneal fluid of women with endometriosis. This study was undertaken to assess the effects of IL-6 and soluble IL-6 receptor (sIL-6R) on in vitro sperm motility. METHODS: Sperm (n = 20) were cultured with IL-6 or sIL-6R, or with a combination of both. After 24 h cultures, sperm motility was evaluated using a computer-assisted semen analysis system. Gene and protein expressions of IL-6, IL-6 receptor (IL-6R), and glycoprotein 130 (gp130) were examined in sperm by RT-PCR analysis and western blot analysis. RESULTS: Addition of IL-6 or sIL-6R individually to the culture media had no affect on sperm motion. However, adding a combination of IL-6 and sIL-6R dose-dependently reduced the percentage of motile and rapidly moving sperm. Adding anti-IL-6R antibody abolished these adverse effects. Sperm expressed the gp130 gene and protein, but not IL-6 or IL-6R. CONCLUSIONS: A combination of IL-6 and sIL-6R may be associated with gp130 expressed in the sperm and reduce sperm motility. IL-6 and sIL-6R may contribute to the pathogenesis of endometriosis-associated infertility. 相似文献
226.
目的 探讨新生儿C6PD缺陷病和晚发性维生素K缺乏症的危害与预防措施。方法 回顾分析1995-2000年儿内科住院的1周-2月(不含2月)的婴儿3104例次,其中病死56例。结果 1周-2月的小婴儿占住院患儿的19.34%,其中新生儿G6PD缺陷病239例,占7.70%;晚发性维生素K缺乏症92例,占2.96%。死因的第2、3位分别是晚发性维生素K缺乏症(13例,占23.21%)和新生儿C6PD缺陷病(12例,占21.43%),两者的病死率分别为14.13%和5.02%,极显著高于(x^2=17.59,P<0.01)或相近于(x^2=0.88,P>0.05)肺炎的3.57%。新生儿G6PD缺陷病合并感染占38.49%、低氧血症占23.35%、低血糖占19.25%、酸中毒占15.90%,继发胆红素脑病占13.81%。晚发性维生素K缺乏症出现抽搐占90.22%、胃肠、注射部位出血占60.89%;CT证实颅内出血占98.91%。结论 1周-2月的小婴儿约占住院患儿的两成,新生儿G6PD缺陷病和晚发性维生素K缺乏症的病死率均很高,两者是除肺炎外最主要的死因。提议制定并推广预防这2种疾病的常规措施,并参照国内外相应的现状拟出其具体内容。 相似文献
227.
Lanari M Papa I Venturi V Lazzarotto T Faldella G Gabrielli L Guerra B Landini MP Salvioli GP 《Journal of medical virology》2003,70(4):628-632
Human herpesvirus 6 (HHV 6) has neurotropic and neuroinvasive properties. The virus has been found in the cerebrospinal fluid of many children with aseptic meningoencephalitis. Intrauterine transmission has been documented by HHV 6 DNA detection in cord blood specimens of apparently healthy newborns and in fetuses following spontaneous abortions. A patient is described with early neonatal afebrile seizures resulting from a congenital HHV 6 variant B infection disclosed by repeated detection of viral genome by polymerase chain reaction (PCR) in cerebrospinal fluid in the first days of life. At follow-up, magnetic resonance imaging (MRI) studies disclosed hyperintensities in the periventricular white matter and basal ganglia, associated with cerebral atrophy. Further follow-up at 18 months revealed poor neurological outcome with mild neurodevelopmental retardation, strabismus and hypertonia of legs. This report provides evidence of neurological involvement after HHV 6 vertical transmission, and the association with neurological sequelae. 相似文献
228.
应用荧光斑点法和比值法检测G6PD 总被引:5,自引:0,他引:5
目的建立适合于G6PD缺乏的新生儿筛查及确诊方法。方法应用荧光斑点法(FST)对新生儿筛查滤纸干血片进行检测,对可疑阳性者召回,抽静脉血以D6PD/6PGD比值法进行确诊,同时结合新生儿父母亲的G6PD结果,根据遗传关系综合分析。结果FST筛查25000例新生儿,G6PD缺乏阳性率为4.56%,确诊检出率为4.09%。与比值法的符合率为90.4%,G6PD重度缺乏者的符合率为100%,G6PD中间缺乏者的符合率为78.5%,室间质量控制结果与反馈结果符合率为100%。结论FST汀具有高的敏感性、特异性和准确性,方法简便、快捷、费用低廉,可对滤纸干血片标本进行大规模的筛查检测,同时利用比值法进行确诊,可减少假阳性及假阴性,有利于早期诊断和防治G6PD缺乏所致的新生儿黄疸和急性溶血。 相似文献
229.
Nakamura M Yamanaka G Kawashima H Watanabe Y Ioi H Kashiwagi Y Takekuma K Hoshika A Hayakawa M Suzuki S 《Disease markers》2005,21(4):199-202
The characteristics of influenza-associated encephalopathy is the high mortality and nimble progress with coma which appears in general cases within 48 hours. Most of patients show no abnormalities in the standard blood checks on admission or in early stage. In this study we investigated if a rapid assay of interleukin (IL)-6 is useful in influenza-associated encephalopathy in early stages. The levels of IL-6 in patients with influenza-associated encephalopathy did not show any significant difference compared with those in patients with febrile convulsion and rotavirus-associated convulsion. However the levels of IL-6 in severe cases were significantly higher than those of mild cases with influenza-associated encephalopathy. Consequently the rapid assay of serum IL-6 is useful to evaluate and decide the therapies. 相似文献
230.
经丝裂霉素C体外处理后,将IL-6基因转染的、高分泌的IL-6的B16黑色素瘤细胞制成瘤苗。结果发现,体内注射IL-6基因转染的瘤苗后,小鼠脾脏CTL活性、NK活性及IL-2诱导的LAK活性显著升高。经IL-6基因转染瘤苗体内治疗后,荷瘤小鼠的皮下肿瘤生长显著减慢、肺转移结节数显著降低、存活期显著延长,若同时合用低剂量IL-2,则上述治疗效果更好。可见IL-6基因转染的瘤苗能有效地通过诱导机体抗肿瘤免疫功能而发挥抗肿瘤作用,与低剂量IL-2合用后,IL-6基因转染的瘤苗的抗肿瘤效果更佳。 相似文献