全文获取类型
收费全文 | 1543篇 |
免费 | 178篇 |
国内免费 | 10篇 |
专业分类
耳鼻咽喉 | 4篇 |
儿科学 | 48篇 |
妇产科学 | 22篇 |
基础医学 | 244篇 |
口腔科学 | 48篇 |
临床医学 | 166篇 |
内科学 | 265篇 |
皮肤病学 | 27篇 |
神经病学 | 146篇 |
特种医学 | 102篇 |
外科学 | 200篇 |
综合类 | 33篇 |
一般理论 | 1篇 |
预防医学 | 238篇 |
眼科学 | 14篇 |
药学 | 124篇 |
中国医学 | 1篇 |
肿瘤学 | 48篇 |
出版年
2021年 | 26篇 |
2020年 | 17篇 |
2019年 | 31篇 |
2018年 | 40篇 |
2017年 | 25篇 |
2016年 | 28篇 |
2015年 | 33篇 |
2014年 | 46篇 |
2013年 | 48篇 |
2012年 | 52篇 |
2011年 | 62篇 |
2010年 | 52篇 |
2009年 | 51篇 |
2008年 | 68篇 |
2007年 | 61篇 |
2006年 | 66篇 |
2005年 | 56篇 |
2004年 | 53篇 |
2003年 | 45篇 |
2002年 | 44篇 |
2001年 | 39篇 |
2000年 | 52篇 |
1999年 | 48篇 |
1998年 | 29篇 |
1997年 | 24篇 |
1996年 | 24篇 |
1995年 | 26篇 |
1994年 | 26篇 |
1993年 | 28篇 |
1992年 | 41篇 |
1991年 | 39篇 |
1990年 | 25篇 |
1989年 | 42篇 |
1988年 | 36篇 |
1987年 | 39篇 |
1986年 | 27篇 |
1985年 | 31篇 |
1984年 | 23篇 |
1983年 | 21篇 |
1982年 | 9篇 |
1981年 | 21篇 |
1980年 | 10篇 |
1979年 | 18篇 |
1978年 | 19篇 |
1977年 | 11篇 |
1975年 | 15篇 |
1971年 | 12篇 |
1970年 | 9篇 |
1967年 | 9篇 |
1966年 | 8篇 |
排序方式: 共有1731条查询结果,搜索用时 15 毫秒
21.
A retrospective analysis of all patients with blunt abdominal trauma associated with haematuria admitted to one hospital (Royal United, Bath) in a 10-year period was conducted to establish the contribution of the intravenous urogram (IVU) in their management. Eighty-one case records were analysed. Of 35 IVUs performed in patients with microscopic (reagentstrip positive) haematuria, only one was abnormal. In contrast, 27 IVUs performed in patients with macroscopic (naked eye) haematuria revealed 17 major injuries and 5 previously unrecognized congenital abnormalities. It is concluded that an IVU is an unnecessary and non-contributory investigation in patients with microscopic haematuria and guidelines are suggested for the role of IVU in patients with blunt abdominal trauma associated with haematuria. 相似文献
22.
Jordi Ortiz Lawrence W. Fitzgerald Maura Charlton Sarah Lane Louis Trevisan Xavier Guitart William Shoemaker Ronald S. Duman Eric J. Nestler 《Synapse (New York, N.Y.)》1995,21(4):289-298
In previous studies, we have demonstrated that chronic administration of morphine or cocaine produces some common biochemical adaptations in the ventral tegmental area (VTA) and nucleus accumbens (NAc), components of the mesolimbic dopamine system implicated in the reinforcing actions of these and other drugs of abuse. Since this neural pathway is also implicated in the reinforcing actions of ethanol, it was of interest to determine whether chronic ethanol exposure results in similar biochemical adaptations. Indeed, as seen for chronic morphine and cocaine treatments, we show here that chronic ethanol treatment increased levels of tyrosine hydroxylase and glial fibrillary acidic protein immunoreactivity, and decreases levels of neurofilament protein immunoreactivity, in the VTA. Also like morphine and cocaine, ethanol increases levels of cyclic AMP-dependent protein kinase activity in the NAc. These actions of ethanol required long-term exposure to the drug, and were in most cases not seen in the substantia nigra or caudate-putamen, components of the nigrostriatal dopamine system studied for comparison. Altered levels of tyrosine hydroxylase in catecholaminergic cells frequently reflect altered states of activation of the cells. Moreover, increasing evidence indicates that ethanol produces many of its acute effects on the brain by regulating NMDA glutamate and GABA receptors. We therefore examined the influence of chronic ethanol treatment on levels of expression of specific glutamate and GABA receptor subunits in the VTA. It was found that long-term, but not short-term, ethanol exposure increased levels of immunoreactivity of the NMDARl subunit, an obligatory component of NMDA glutamate receptors, and of the Glu Rl subunit, a component of many AMPA glutamate receptors; but at the same time, long-term ethanol exposure decreased immunoreactivity levels of the α1 subunit of the GABAA receptor complex. These changes are consistent with an increased state of activation of VTA neurons inferred from the observed increase intyrosine hydroxylase (TH) expression. These results demonstrate that chronic ethanol exposure results in several biochemical adaptations in the mesolimbic dopamine system, which may underlie prominent changes in the structural and functional properties of this neural pathway related to alcohol abuse and alcoholism. © 1995 Wiley-Liss, Inc. 相似文献
23.
24.
Brooks TD Slomp J Quax PH De Bart AC Spencer MT Verheijen JH Charlton PA 《Clinical & experimental metastasis》2000,18(6):445-453
Recent reports suggest that elevated levels of plasminogen activator inhibitor-1 (PAI-1) may contribute to tumour progression.
The studies reported here were designed to help elucidate PAI-1's contribution to the invasive and migratory phenotype. Antibodies
to PAI-1 dose-dependently, and significantly, inhibited the invasive and migratory potential of human HT1080 fibrosarcoma
cells, as did an antibody to uPA and the plasmin inhibitor aprotinin. Invasion of the human melanoma cell line, BLM, was also
attenuated by the anti-PAI-1 monoclonal antibody MAI-12. The non-invasive human melanoma cell line, IF6, which does not express
uPA, provided further confirmation of PAI-1 and uPA's role as, upon transfection with uPA, this cell line attained an invasive
phenotype, which was again attenuated by MAI- 12. Although antibodies to PAI-1 did not affect the adhesion of HT1080 cells
to vitronectin, the antibody to uPA reduced their attachment. Addition of exogenous PAI-1, however, prevented HT1080 cell
adhesion (IC50 180nM) and promoted cell detachment from vitronectin. Furthermore melanoma cells transfected with a uPA variant, which had
an impaired interaction with PAI-1, were not invasive and had impaired binding to vitronectin. These data highlight the importance
of a balanced proteolysis and suggest an additional role for PAI-1 distinct from its role in proteolysis. These data also
suggest that uPA and PAI-1 may co-operate in the migratory process by respectively facilitating the attachment to, and subsequent
detachment from, vitronectin in the extracellular matrix. These results support the clinical findings and indicate that modulation
of PAI-1 activity may be of therapeutic benefit for the treatment of cancer.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
25.
Use of 125I-secretin to identify and characterize high-affinity secretin receptors on pancreatic acini 总被引:1,自引:0,他引:1
R T Jensen C G Charlton H Adachi S W Jones T L O'Donohue J D Gardner 《The American journal of physiology》1983,245(2):G186-G195
We prepared 125I-secretin and studied the kinetics, stoichiometry, and chemical specificity with which the labeled peptide binds to dispersed acini prepared from guinea pig pancreas. Iodinated secretin retained intrinsic biological activity in that it was as effective but 2.5-times less potent than native secretin in its ability to bind to pancreatic acini and to increase cellular cAMP. Scatchard analysis of binding of 125I-secretin indicated that each pancreatic acinar cell has approximately 93,000 binding sites, half of which are occupied by 11 nM iodinated secretin. Binding of 125I-secretin was rapid, reversible, saturable, specific, and temperature dependent. Binding of 125I-secretin was inhibited by secretin, vasoactive intestinal peptide, PHI, and Gila monster venom but not by glucagon, gastric inhibitory polypeptide, cholecystokinin, caerulein, gastrin, bovine pancreatic polypeptide, somatostatin, neurotensin, leucine-enkephalin, methionine-enkephalin, carbachol, bombesin, litorin, eledoisin, physalaemin, or substance P. With agonists (secretin, vasoactive intestinal peptide, PHI, or Gila monster venom), as well as antagonists (C-terminal fragments of secretin), there was a close correlation between their relative potencies for inhibiting binding of 125I-secretin and their relative potencies for increasing cAMP (agonists) or inhibiting the secretin-induced increase in cAMP (antagonists). For a given agonist, however, a 40-fold higher concentration was required for half-maximal inhibition of binding of 125I-secretin than was required to produce a half-maximal increase in cellular cAMP. Thus, maximal stimulation of cellular cAMP occurs when approximately one-third of the secretin receptors are occupied by an agonist. 相似文献
26.
Liu JQ; Bai XF; Shi FD; Xiao BG; Li HL; Levi M; Mustafa M; Wahren B; Link H 《International immunology》1998,10(8):1139-1148
Induction of mucosal tolerance by inhalation of soluble peptides with
defined T cell epitopes is receiving much attention as a means of
specifically down-regulating pathogenic T cell reactivities in autoimmune
and allergic disorders. Experimental autoimmune encephalomyelitis (EAE)
induced in the Lewis rat by immunization with myelin basic protein (MBP)
and Freund's adjuvant (CFA) is mediated by CD4+ T cells specific for the
MBP amino acid sequences 68-86 and 87-99. To further define the principles
of nasal tolerance induction, we generated three different MBP peptides
(MBP 68-86, 87-99 and the non- encephalitogenic peptide 110-128), and
evaluated whether their nasal administration on day -11, -10, -9, -8 and -7
prior to immunization with guinea pig MBP (gp-MBP) + CFA confers protection
to Lewis rat EAE. Protection was achieved with the encephalitogenic
peptides MBP 68-86 and 87-99, MBP 68-86 being more potent, but not with MBP
110-128. Neither MBP 68-86 nor 87-99 at doses used conferred complete
protection to gp-MBP-induced EAE. In contrast, nasal administration of a
mixture of MBP 68-86 and 87-99 completely blocked gp-MBP-induced EAE even
at lower dosage compared to that being used for individual peptides. Rats
tolerized with MBP 68-86 + 87-99 nasally showed decreased T cell responses
to MBP reflected by lymphocyte proliferation and IFN-gamma ELISPOT assays.
Rats tolerized with MBP 68-86 + 87-99 also had abrogated MBP-reactive
IFN-gamma and tumor necrosis factor-alpha mRNA expression in lymph node
cells compared to rats receiving MBP 110-128 nasally, while similar low
levels of MBP-reactive transforming growth factor-beta and IL-4 mRNA
expressing cells were observed in the two groups. Nasal administration of
MBP 68-86 + 87-99 only slightly inhibited guinea pig spinal cord
homogenate-induced EAE, and passive transfer of spleen mononuclear cells
from MBP 68-86 + 87-99-tolerized rats did not protect naive rats from EAE.
Finally, we show that nasal administration of MBP 68-86 + 87-99 can reverse
ongoing EAE induced with gp-MBP, although higher doses are required
compared to the dosage needed for prevention. In conclusion, nasal
administration of encephalitogenic MBP peptides can induce antigen-specific
T cell tolerance and confer incomplete protection to gp-MBP-induced EAE,
and MBP 68-86 and 87-99 have synergistic effects. Non-regulatory mechanisms
are proposed to be responsible for tolerance development after nasal
peptide administration.
相似文献
27.
Mathers ME Shrimankar J Scott DJ Charlton FG Griffith CD Angus B 《Journal of clinical pathology》2001,54(10):809-811
AIM: To determine whether the introduction of a standard reporting proforma has led to an improvement in the completeness of histopathology reports for breast cancer excision specimens. METHODS: A standard reporting proforma was designed using the Royal College of Pathologists' minimum dataset for breast cancer histopathology reports and the national histopathology reporting form of the National Health Service (NHS) breast screening programme. This was introduced into our department in June 1999, with reports generated from the proforma replacing the standard text reports. The pathological information contained in 50 text reports issued before the introduction of the proforma and 50 reports generated using the proforma was compared with the minimum dataset and NHS breast screening programme guidelines. RESULTS: A general improvement in documentation of individual pathological features was noted after introduction of the proforma. This was most significant in relation to documentation of features, such as microcalcification and ductal carcinoma in situ. In addition, important features such as tumour grade, tumour size, and hormone receptor status were documented more frequently in the proforma group. There was an overall increase in the number of reports regarded as complete after introduction of the proforma. CONCLUSIONS: The introduction of a standard proforma led to a significant improvement in the completeness of breast cancer histopathology reports in this centre, but continued vigilance is needed to ensure that standards continue to improve. 相似文献
28.
29.
Development and characterization of a whole-cell radioligand binding assay for [125I]gp120 of HIV-1.
L P To V Balasubramanian M E Charlton T A Francis C Doyle P M Sweetnam 《Journal of immunoassay》1992,13(1):61-83
The binding of HIV-1 envelope glycoprotein, gp120, to the CD4 receptor is an important step in productive infection. The development of agents which interrupt this binding phenomenon should be of therapeutic interest. The present study characterizes a whole cell gp120/CD4 radioligand binding assay (radioligand binding assay) modified for use in a high volume screening format. Modifications include the use of human CD4 receptor stably expressed in a Chinese hamster ovary cell line and the gentle fixation (paraformaldehyde) of the CD4 receptor just prior to assay. Binding of [125I]gp120 to fixed CD4 was of high affinity (KD = 6 nM), saturable, reversible, and specific. The kinetics of binding were identical to those of viable (non-fixed) CD4 receptor. [125I]gp120 binding was inhibited by unlabeled recombinant gp120, soluble CD4, and the anti-CD4 monoclonals OKT4A and LEU3A. A number of compounds reported to inhibit gp120 binding and/or gp120 induced syncytium formation were also active in this assay. This modified radioligand binding assay was developed to initiate a rational and extensive screening program to assist in the identification of potential chemotherapeutic agents based on their ability to inhibit gp120 binding to host cells. 相似文献
30.