全文获取类型
收费全文 | 18859篇 |
免费 | 1062篇 |
国内免费 | 618篇 |
专业分类
耳鼻咽喉 | 106篇 |
儿科学 | 134篇 |
妇产科学 | 2139篇 |
基础医学 | 2528篇 |
口腔科学 | 537篇 |
临床医学 | 1001篇 |
内科学 | 1424篇 |
皮肤病学 | 242篇 |
神经病学 | 1315篇 |
特种医学 | 435篇 |
外国民族医学 | 2篇 |
外科学 | 1446篇 |
综合类 | 2417篇 |
现状与发展 | 2篇 |
一般理论 | 2篇 |
预防医学 | 1068篇 |
眼科学 | 172篇 |
药学 | 3852篇 |
2篇 | |
中国医学 | 995篇 |
肿瘤学 | 720篇 |
出版年
2024年 | 25篇 |
2023年 | 133篇 |
2022年 | 298篇 |
2021年 | 429篇 |
2020年 | 354篇 |
2019年 | 328篇 |
2018年 | 373篇 |
2017年 | 415篇 |
2016年 | 464篇 |
2015年 | 426篇 |
2014年 | 873篇 |
2013年 | 1369篇 |
2012年 | 975篇 |
2011年 | 1252篇 |
2010年 | 1051篇 |
2009年 | 972篇 |
2008年 | 933篇 |
2007年 | 964篇 |
2006年 | 888篇 |
2005年 | 811篇 |
2004年 | 721篇 |
2003年 | 697篇 |
2002年 | 562篇 |
2001年 | 521篇 |
2000年 | 458篇 |
1999年 | 431篇 |
1998年 | 424篇 |
1997年 | 375篇 |
1996年 | 300篇 |
1995年 | 332篇 |
1994年 | 275篇 |
1993年 | 269篇 |
1992年 | 234篇 |
1991年 | 217篇 |
1990年 | 192篇 |
1989年 | 188篇 |
1988年 | 128篇 |
1987年 | 121篇 |
1986年 | 131篇 |
1985年 | 127篇 |
1984年 | 113篇 |
1983年 | 58篇 |
1982年 | 67篇 |
1981年 | 53篇 |
1980年 | 56篇 |
1979年 | 36篇 |
1978年 | 32篇 |
1977年 | 25篇 |
1976年 | 17篇 |
1972年 | 11篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
31.
H Van Dekken E W Schervish J G Pizzolo W R Fair M R Melamed 《The Journal of pathology》1991,164(1):17-22
We have used fluorescent in situ hybridization and simultaneous in vivo bromodeoxyuridine labelling of a solid bladder cancer to examine tumour cell subsets for possible proliferative growth differences. In this dual-labelled preparation, most tumour cell nuclei exhibited monosomy 9, consistent with reported karyotypes of bladder cancer. Incorporated bromodeoxyuridine was visualized with a fluoresceinated antibody in 5-6 per cent of the tumour cells, concordant with S-phase estimates by cell cycle analysis of the flow cytometric DNA histogram. A majority of the bromodeoxyuridine-positive cells also carried the monosomy 9 chromosome abnormality. This is the first report to demonstrate the feasibility of combined in situ hybridization and detection of bromodeoxyuridine incorporated in vivo in human tumour cells in order to provide information on the growth rate of specific subsets of tumour cells identified by chromosomal constitution. 相似文献
32.
N. A. T. Lusamvuku P. Aubineau R. Sercombe 《Medical & biological engineering & computing》1980,18(5):643-649
A new method is described for simultaneous measurements of electrical and mechanical activity in an intact segment of a small
artery (outside diameter 0·3–0·5 mm). A 7–9 mm segment of rabbit middle-cerebral artery was ligated on a Teflon tube connected
to a perfusion circuit. The presence of a plug in the tube, flanked by two orifices, forced the physiological solution to
flow in the annular space between the tube and the artery wall. Physiological pressures could thus be attained at low rates
of flow, and the pressure, measured upstream, was significantly modifed by the slightest constriction or dilatation of the
vascular segment. Electrical recording with glass microelectrodes was performed on a short immobilised portion of the artery.
The artery and tube were bathed in a physiological solution at 38°C, but perfusing and incubating solutions did not mix. Spontaneous
electrical and mechanical activity of middle cerebral arteries is described, together with modifications induced by vasoactive
agents. 相似文献
33.
Sperm morphological assessment based on strict criteria and in-vitro fertilization outcome. 总被引:1,自引:0,他引:1
T Kobayashi M Jinno K Sugimura S Nozawa T Sugiyama E Iida 《Human reproduction (Oxford, England)》1991,6(7):983-986
One-hundred-and-twenty-three in-vitro fertilization (IVF) cycles were analysed in order to clarify the influence of strictly normal morphology (SNM) of spermatozoa on IVF outcome. SNM was defined using strict criteria according to Kruger with our modifications. The IVF cycles studied were divided into three groups: %SNM less than 12% (13 cycles), 12 less than 40% (68 cycles), greater than or equal to 40% (42 cycles). The cleavage rates per oocyte were higher in the groups with 12-40% and greater than or equal to 40% of %SNM than in the group with %SNM less than 12%. The embryo transfer rate per cycle increased with increasing %SNM. The overall pregnancy rate per cycle increased with increasing %SNM (7.7% in %SNM less than 12%, 22.1% in 12-40% of %SNM, and 40.5% in %SNM greater than or equal to 40%). The ongoing pregnancy rate per cycle also increased with increasing %SNM (7.7% in %SNM less than 12%, 14.7% in 12-40% of %SNM, and 31.0% in %SNM greater than or equal to 40%). The miscarriage rate was lower in %SNM greater than or equal to 40% (23.5%) than in 12-40% of %SNM (33.3%). It was suggested that %SNM is a good predictor of IVF outcome. 相似文献
34.
Kawakubo Y Kishimoto H Sato Y Yanagimoto K Tsuruta T Ogawa Y Kameya T 《Virchows Archiv : an international journal of pathology》1999,434(2):109-115
Langerhans cell histiocytosis (LCH) has been thought to be a disorder of immune regulation, and increasingly, evidence showing
that the tissue damage in LCH involves lymphokines and pro-inflammatory cytokines is reported. We detected human cytomegalovirus
(HCMV)-DNA in LCH cells in the foci of LCH lesions by immunohistochemistry, in situ hybridization and PCR. HCMV was detected
in the nuclei and/or cytoplasm of LCH cells in 9 of 27 LCH cases by immunostaining. HCMV was probably an early antigen. In
situ hybridization revealed signals for HCMV-DNA only in the nuclei of LCH cells in 10 of the 27 LCH cases. PCR analysis was
performed in 20 of the LCH cases, and HCMV-DNA was detected in 7 of these. All 7 positive cases were also positive for HCMV
by ISH and IHC. These findings suggested that early phase infection or reactivation of HCMV occurred in the LCH lesions. HCMV
infection may be accompanied by impaired cytokine production. Our study also suggested a relationship between HCMV infection
and expression of TNFα. In tissues affected by LCH, dermatopathic lymphadenopathy or malignant fibrous histiocytoma and in
normal tissues no signals for Epstein-Barr virus-RNA were detected. These findings suggest that in some cases LCH is associated
with HCMV infection.
Received: 24 November 1998 / Accepted: 24 April 1998 相似文献
35.
以乙肝疫苗、人喉癌细胞膜抗原为抗原,猪脾细胞为效应细胞,经体外免疫后收集应答细胞,制备PSHBV-TF PSAC-iRNA。通过抗原特异性细胞免疫功能试验证实,PSHBV-TF和PSAC-iRNA都能转移特异性细胞免疫功能。采用体外免疫法制备PSHBV-TF和PSAC-iRNA是可行的,并且具有诸多优点。 相似文献
36.
Hunter S Weiss S Ou CY Jaye D Young A Wilcox J Arbiser JL Monson D Goldblum J Nolen JD Varma V 《Human pathology》2005,36(9):987-993
Apolipoprotein D (apoD) expression was studied in nonneoplastic peripheral nerve, neurofibromas (NFs), and malignant peripheral nerve sheath tumors (MPNSTs) by quantitative polymerase chain reaction, in situ hybridization, and immunohistochemistry. Multiplex quantitative polymerase chain reaction for messenger RNA was performed on a series of formalin-fixed and paraffin-embedded specimens that included 9 MPNSTs, 12 NFs, and 4 normal peripheral nerves. The average apoD expression was 108-fold decreased (DeltaCt = -7.3) in the MPNSTs compared with the NFs (P < .05). ApoD expression levels were 3.0-fold elevated (DeltaCt = 1.7) in the NFs compared with nonneoplastic peripheral nerve (P < .05). In situ hybridization for apoD RNA was performed on a separate series of 10 cases in which each microscopic section included both MPNST and the NF from which it arose. These studies confirmed elevated apoD expression in NFs compared with MPNSTs and demonstrated that this expression was variable among individual cells within the NFs. Differential expression by immunohistochemistry could only be demonstrated in selected areas, most likely because apoD protein is a small molecule that is secreted out of the cell into the extracellular space and plasma. ApoD expression initially increases a small amount with the formation of NFs from nonneoplastic peripheral nerve and subsequently decreases markedly as NFs transform into MPNSTs. This expression pattern may serve as a marker for cell cycle inhibition during peripheral nerve tumorigenesis. 相似文献
37.
Opsahl Michael S.; Fitz Tony A.; Rexroad Caird E. Jr; Fritz Marc A. 《Human reproduction (Oxford, England)》1996,11(6):1250-1255
We examined the effects of enclomiphene and zuclomiphene, aloneand in combination with oestradiol, on basal and gonadotrophin-stimulatedprogesterone secretion by isolated subpopulations of both large(granulosa-lutein) and small (theca-lutein) ovine luteal cells.Isolated large and small luteal cells derived from intact, enucleatedovine corpora lutea were incubated for 48120 h with orwithout 22R-hydroxycholesterol or pregnenolone (2.5 µM)and a range of enclomiphene, zuclomiphene, and/or oestradiolconcentrations (3100 µM), both with and withoutovine Iuteinizing hormone (100 ng/ml). Spent media were assayedin duplicate for progesterone content by radioimmunoassay. Enclomiphene,zuclomiphene, and oestradiol exhibited equivalent dose-dependentinhibitory effects on basal and gonadotrophin-stimulated smalland large ovine luteal cell progesterone secretion under allsubstrate conditions. Both cell types became more sensitiveto clomiphene inhibition with increasing time in culture. Incombined treatments, the effects of oestradiol and either enclomipheneor zuclomiphene became additive in longer-term cultures andwere never antagonistic In this model system, (i) clomiphene,like oestradiol, appears to inhibit 3-hydroxysteroid dehy-drogenaseactivity, (ii) both stereoisomers act as oestrogen agonists,(iii) neither demonstrates any anti-oestrogenic properties,and (iv) both large and small luteal cells become more sensitiveto clomiphene inhibition with increasing duration of exposure. 相似文献
38.
In situ fluorescence hybridization of Y translations: cytogenetic analysis using probes Y190 and Y431 总被引:1,自引:0,他引:1
Two moderately repetitive DNA probes (Y190 and Y431) and a fluorescent in situ hybridization technique, using a biotin, avidin, anti-avidin system, were employed to investigate a group of patients with Y chromosome abnormalities. In normal male subjects, a bright fluorescent spot could be detected in cells in interphase and on the short arm of the Y chromosome in metaphase spreads. Translocations of DNA fragments of the short arm of the Y chromosome to autosomes 10, 13 and 15 were observed in five patients. In a 45,XX male subject the translocation involved one of the X chromosomes. With this in situ hybridization procedure, bright fluorescent spots were also noticed in uncultured amniotic cells and chorionic cellular elements from male fetuses, thus allowing a rapid and reproducible approach to prenatal fetal sexing. 相似文献
39.
N. Lindefors S. Brené M. Herrera-Marschitz H. Persson 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》1990,80(3):489-500
Summary In situ hybridization was used to study the expression of prepro-neuropeptide Y (NPY), preprosomatostatin (SOM), preprotachykinin (PPT) and preprocholecystokinin (CCK) mRNA in caudate-putamen and frontoparietal cortex of rat brain with unilateral lesion of midbrain dopamine neurons. Neurons expressing NPY and SOM mRNA showed a similar distribution and the expression of both NPY and SOM appears to be regulated by dopamine in a similar fashion. Following a dopamine deafferentation, the numerical density of both NPY and SOM mRNA producing neurons almost doubled in the lesioned caudate-putamen with no change in the average grain density over positive neurons. Hence, in the intact caudate-putamen dopamine appears to suppress expression of these two neuropeptide genes leading to an activation of both NPY and SOM mRNA expression in many non- or low-expressing neurons when the level of dopamine is decreased. In the fronto-parietal cortex, on the other hand, dopamine appears to stimulate NPY and SOM gene expression. Thus, in the absence of dopamine about half of the NPY positive neurons disappeared. However, for SOM the number of positive neurons did not change, but rather most positive neurons appeared to have down-regulated their SOM mRNA expression. No evidence was found for a change in CCK mRNA expression by the dopamine deafferentation, while PPT mRNA expression decreased in the deafferented caudate-putamen. Consequently, dopamine exerts dissimilar effects on the expression of different neuropeptide genes, that in turn do not respond in the same way in different brain regions. 相似文献
40.
原位PCR技术检测石蜡包埋脑组织中人巨细胞病毒DNA 总被引:6,自引:0,他引:6
应用原位聚合酶链反应(ISPCR)技术检测了25例尸检畸形胎儿石蜡包埋脑组织中人巨细胞病毒(HCMV)DNA,并与普通PCR及原位杂交(ISH)进行了比较。ISPCR、PCR及ISH检测阳性率分别为44%,36%及20%。与ISH相比较,ISPCR不仅检出阳性率高,而且信号强度增强。研究结果提示,IS-PCR是诊断HCMV感染的快速、敏感、特异的实用方法。 相似文献