全文获取类型
收费全文 | 578篇 |
免费 | 34篇 |
国内免费 | 19篇 |
专业分类
耳鼻咽喉 | 3篇 |
儿科学 | 26篇 |
妇产科学 | 14篇 |
基础医学 | 57篇 |
口腔科学 | 11篇 |
临床医学 | 77篇 |
内科学 | 161篇 |
皮肤病学 | 13篇 |
神经病学 | 32篇 |
特种医学 | 44篇 |
外科学 | 70篇 |
综合类 | 22篇 |
预防医学 | 28篇 |
眼科学 | 4篇 |
药学 | 45篇 |
肿瘤学 | 24篇 |
出版年
2018年 | 5篇 |
2016年 | 8篇 |
2015年 | 14篇 |
2014年 | 18篇 |
2013年 | 18篇 |
2012年 | 12篇 |
2011年 | 12篇 |
2010年 | 35篇 |
2009年 | 24篇 |
2008年 | 23篇 |
2007年 | 20篇 |
2006年 | 13篇 |
2005年 | 12篇 |
2003年 | 8篇 |
2002年 | 7篇 |
2001年 | 9篇 |
2000年 | 11篇 |
1999年 | 15篇 |
1998年 | 30篇 |
1997年 | 19篇 |
1996年 | 25篇 |
1995年 | 12篇 |
1994年 | 12篇 |
1993年 | 15篇 |
1992年 | 6篇 |
1991年 | 14篇 |
1990年 | 7篇 |
1989年 | 18篇 |
1988年 | 16篇 |
1987年 | 9篇 |
1986年 | 6篇 |
1985年 | 7篇 |
1983年 | 4篇 |
1982年 | 7篇 |
1981年 | 3篇 |
1980年 | 7篇 |
1979年 | 3篇 |
1976年 | 4篇 |
1975年 | 3篇 |
1972年 | 3篇 |
1962年 | 3篇 |
1959年 | 15篇 |
1958年 | 16篇 |
1957年 | 14篇 |
1956年 | 10篇 |
1955年 | 15篇 |
1954年 | 19篇 |
1952年 | 5篇 |
1949年 | 3篇 |
1948年 | 4篇 |
排序方式: 共有631条查询结果,搜索用时 15 毫秒
1.
目的 探讨血管新生指标CD34、CD31、vWF、Ⅳ型胶原纤维及层粘连蛋白在肝细胞肝癌(HCC)中的表达及意义 ,同时比较上述几种血管新生因子与增殖细胞核抗原 (PCNA)、病理指标及预后的相关性 ,以便筛选出有效的临床预后指标。方法 采用免疫组化方法 ,对 5 3例肝细胞肝癌的标本进行CD31、CD34、vWF、Ⅳ型胶原纤维及层粘连蛋白的染色、计数 ,并用检测数据与患者的临床资料进行统计分析。结果 统计染色的血管面积后发现 ,CD34与多种临床病理指标无相关性 ;CD31与肝内门静脉浸润相关 ;vWF与肿瘤的TNM分期及肝内门静脉浸润呈正相关 ;CollⅣ与肝内门静脉浸润呈正相关、与术后生存期呈负相关 ;Lam与肝硬化及术中出血量呈负相关、与术后生存期呈正相关。PCNA与肿瘤TNM分期有关。结论 在HCC中 ,CollⅣ、vWF、及CD31为肝细胞肝癌的有效血管新生及预后指标 ;Lam则与肝硬化及术中出血相关 ;PCNA指数肿瘤分期有关 ;CD34不能用作血管新生或预后指标 相似文献
2.
The impairment of the functions of red blood cells or their destruction during storage can be delayed or even inhibited by oligoamines especially RE 1492 (N,N',N'-Tris-(4-phenylbutyl)benzene-1,3,5-trimethanamine). When citrated whole blood (WB) is stored at 4 degrees C for 7 d half of the red blood cells (RBC) have lost their ability to form rouleaux. Addition of 100 mumols/L RE 1492 maintains 50% reaggregability up to day 28th of storage. When citrated WB is stored at 37 degrees C the reaggregability has declined to 40 percent after 10 h. With 100 mumols/L RE 1492 no reduction of this property is observed up to 48 h. These results are correlated with the maintainance of the discocyte form of RBC and a persistent filtrability of RBC suspensions through a 5 microns microporous membrane. With 100 mumols/L RE 1492 only one fifth of the haemolysis of untreated WB occurs. The efflux of potassium ions from RBC into the blood plasma during a 72 h storage is bisected by RE 1492. The binding of oxygen to RBC remains unchanged. 相似文献
3.
A. TSATSOULIS E. WHITEHEAD J. ST. JOHN S. M. SHALET W. R. ROBERTSON 《Clinical endocrinology》1987,27(6):683-689
Eighteen men (mean age 27, range 18-30 years) treated for Hodgkin's disease with 6-8 courses of MVPP (Mustine, Vinblastine, Procarbazine and Prednisolone) have had Leydig cell function assessed by their steroidogenic responses to stimulation by a single bolus dose of HCG (1000 units intramuscularly). Normal age-matched men (n = 16) acted as controls. Baseline immunoreactive FSH was markedly raised in the patients (mean 18.1 +/- SD 6.9 vs 2.0 +/- 1.5 IU/l, P less than 0.0001) reflecting damage to the germinal epithelium. Immunoreactive LH was also greater in patients (10.3 +/- 3.9 IU/l) than in controls (3.9 +/- 1.9 IU/l, P less than 0.0001). There were no differences between the baseline testosterone, androstenedione, oestradiol, oestrone and sex hormone binding globulin (SHBG) concentrations. The testosterone/SHBG ratios were similar in the two groups and there was no correlation between baseline LH and testosterone concentrations or testosterone/SHBG ratios. Testosterone, androstenedione, oestradiol and oestrone secretion in response to HCG stimulation were similar at 24 h and 96 h in both groups. In order to explain the paradox of elevated immunoreactive LH in the face of normal testicular steroidogenesis in such patients, LH biological activity (B) as well as LH immunoreactivity (I) and FSH and testosterone were estimated in a second similar group of patients (n = 17, mean age 27, range 17-43 years) and in a further age-matched control group (n = 17). Bioactive and immunoreactive LH levels were significantly increased (P less than 0.005 and P less than 0.001, respectively) in the patient group.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
4.
Membrane flow within the myelin sheath in IDPN neuropathy 总被引:1,自引:0,他引:1
A. E. BLAUROCK M. B. GENTER ST CLAIR D. G. GRAHAM 《Neuropathology and applied neurobiology》1991,17(4):309-321
This report describes some aspects of beta,beta'-iminodipropionitrile (IDPN) neuropathy in rats as observed by ultrastructural methods and X-ray diffraction. Light microscopy shows gross swelling of the axons in proximal lumbar spinal roots 8 days after intraperitoneal injection of IDPN. Mean axon cross-sectional area and mean axon perimeter increased to 280% and 160% of their control values, respectively. At the same time, myelin membrane packing was not visibly disturbed. In addition, X-ray diffraction patterns, recorded under physiological conditions, demonstrate that the myelin lipid bilayer thickness and widths of the aqueous spaces between bilayers did not change. Related observations are made on posterior tibial nerve (PNS myelin) and ventral spinal cord (CNS myelin). The various observations together are interpreted in terms of a fluid myelin membrane. It is proposed that the myelin membrane flows during axon swelling even though normal membrane-membrane contacts are maintained within the sheath. Membrane flow and slippage between membranes are explained in terms of a molecular model of the myelin multilayer. 相似文献
5.
N. J. ST. G. SAUNDERS Lecturer C. BARCLAY Registrar 《BJOG : an international journal of obstetrics and gynaecology》1988,95(10):1060-1062
Summary. In a randomized controlled study of wound suction drainage after transverse suprapubic incision for lower-segment caesarean section no significant advantages could be demonstrated for routine drainage in terms of wound infection, haematoma formation, duration of hospital stay or analgesic requirements. 相似文献
6.
7.
Krushkal J; Xiong M; Ferrell R; Sing CF; Turner ST; Boerwinkle E 《Human molecular genetics》1998,7(9):1379-1383
Elevated blood pressure is an important risk factor for renal-, cerebro-
and cardiovascular diseases. We used an efficient discordant sib-pair
ascertainment scheme to investigate the impact of the distal end of the
long arm of human chromosome 5 (chromosomal region 5q31.1-qter) containing
genes for the alpha1B and beta2 adrenergic receptors and the dopamine
receptor type 1A on variation of systolic blood pressure in young
Caucasians. We measured eight highly polymorphic markers spanning this
positional candidate gene-rich region in 427 individuals from 55
three-generation pedigrees containing 69 discordant sibling pairs, and
calculated multipoint identity by descent (MIBD) probabilities. The results
of genetic linkage and association tests indicate that the region between
markers D5S2093 and D5S462 is significantly linked to one or more
polymorphic genes influencing interindividual variation in systolic blood
pressure levels. Since the alpha1B adrenergic receptor and dopamine
receptor type 1A genes are located close to these markers, these data
suggest that genetic variation in one or both of these G protein-coupled
receptors, which participate in the control of vascular tone, plays an
important role in influencing interindividual variation in systolic blood
pressure levels.
相似文献
8.
Genetic control of natural immunity to ecotropic mouse leukemia viruses: production of endogenous immunogen.
下载免费PDF全文
![点击此处可从《Infection and immunity》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Mice of the AKR and C57L strains naturally produced low titers of antibody against ecotropic murine leukemia viruses (MuLV). The F1 hybrid of these strains produced anti-MuLV antibody in higher titer than mice of either of the parental strains. Progeny of the genetic backcross C57L X (AKR X C57L)F1 segregated for the production of infectious ecotropic MuLV (according to the Akv-1 and Akv-2 loci) and for the production of antibody against MuLV. All mice that contained infectious MuLV produced anti-MuLV antibodies. Thus, the persistent production of high-titered MuLV in these mice did not result in immunological tolerance towards viral antigens. In contrast, mice that did not contain infectious MuLV could be separated into antibody-producing and -nonproducing classes. The absence of detectable antibody to MuLV in an individual mouse was invariably associated with a virus-free phenotype. Antibody against MuLV reacted primarily with p15 and gp70 proteins of the viral envelope. It was concluded that overt production of endogenous ecotropic MuLV served as a major immunogenic stimulus for the production of anti-MuLV antibody in these mice. 相似文献
9.
S. T. Kaehler N. Singewald A. Philippu 《Naunyn-Schmiedeberg's archives of pharmacology》1999,359(6):460-465
The aim of the present work was to clarify whether differences exist between the release of endogenous serotonin in the locus
coeruleus of normotensive and hypertensive rats. The locus coeruleus was superfused with artificial cerebrospinal fluid (aCSF)
through a push-pull cannula and serotonin and its metabolite 5-hydroxyindoleacetic acid (5-HIAA) were determined in the superfusate
by HPLC combined with electrochemical detection. Compared with normotensive Wistar-Kyoto (WKY) rats, the basal release rate
of serotonin in the locus coeruleus of spontaneously hypertensive rats (SHR) was increased more than twofold. Intravenous
infusion of noradrenaline (4 μg/kg min) increased mean arterial blood pressure to the same extent in hypertensive and normotensive
rats. The pressor response was associated with an increased serotonin release. In WKY rats, the release of serotonin in the
locus coeruleus evoked by noradrenaline infusion was more pronounced than in SHR. In WKY rats, intravenous infusion of sodium
nitroprusside (150 μg/kg min) led to a fall in blood pressure which was less pronounced and lasted shorter than in SHR. The
depressor response was associated with decreased serotonin release. In WKY rats, the decrease in serotonin release evoked
by sodium nitroprusside was more pronounced and lasted longer than in SHR. Neither noradrenaline nor sodium nitroprusside
influenced the outflow of 5-HIAA. The sensory stimuli noise and tail pinch led to a slight rise in arterial blood pressure
which was similar in WKY rats and SHR. These stimuli enhanced the release rate of serotonin and the outflow of 5-HIAA to the
same extent in the locus coeruleus of normotensive and hypertensive rats. The findings suggest that the enhanced release of
serotonin in the locus coeruleus of genetically hypertensive rats reflects a mechanism counteracting the disturbed blood pressure
homeostasis. Stressors influence blood pressure and release of serotonin in the locus coeruleus of SHR and WKY rats to the
same extent.
Received: 16 November 1998 / Accepted: 22 February 1999 相似文献
10.
Kaehler ST Philippu A Singewald N 《Naunyn-Schmiedeberg's archives of pharmacology》1999,359(3):187-193
Previously, we have shown that in the presence of pargyline the release of serotonin (5-HT) in the locus coeruleus is modulated
by various sensory stimuli and blood pressure fluctuations. The aim of the present study was to investigate whether local
inhibition of monoamine oxidase (MAO) influences basal and stimulus-induced release of 5-HT in the locus coeruleus. For this
purpose, the locus coeruleus was superfused in the absence and in the presence of the MAO inhibitor pargyline. Additionally,
we examined whether the release of the 5-HT metabolite 5-hydroxy-indole acetic acid (5-HIAA) in the locus coeruleus is altered
in response to stimuli. The locus coeruleus of the conscious rat was superfused through a push-pull cannula with artificial
cerebrospinal fluid (CSF). 5-HT and 5-HIAA were determined in the superfusate. The basal release rate of 5-HT and the basal
outflow of 5-HIAA averaged 2.0 fmol/min and 69 fmol/min, respectively. The basal release rate of 5-HT and the 5-HIAA outflow
were tetrodotoxin (TTX)-sensitive. In the absence of pargyline, the sensory stimuli noise stress or tail pinch, applied for
10 min, increased 5-HT and 5-HIAA outflow by 50–70%. In contrast, an experimentally induced rise in blood pressure for 10
min enhanced 5-HT release by 50%, but had no effect on 5-HIAA outflow. The release of 5-HT and/or 5-HIAA elicited by sensory
stimuli or a blood pressure rise was abolished by TTX. Addition of pargyline to the CSF enhanced 5-HT release fourfold and
slightly decreased 5-HIAA outflow. These levels remained stable throughout the entire observation period of 8 h. In the presence
of pargyline, 5-HT release elicited by noise, tail pinch and increase in blood pressure was enhanced. It is concluded that
superfusion with pargyline enhances 5-HT release and reduces 5-HIAA outflow in the locus coeruleus. Furthermore, the ability
of sensory stimuli and baroreceptor activation to enhance 5-HT release is preserved during a prolonged pargyline-induced increase
in extracellular 5-HT. Since sensory stimuli enhanced, while baroreceptor activation did not influence 5-HIAA outflow, 5-HIAA
is not a reliable index for short-term changes in the activity of serotonergic neurons in the locus coeruleus.
Received: 13 July 1998 / Accepted: 10 December 1998 相似文献