全文获取类型
收费全文 | 1302篇 |
免费 | 145篇 |
国内免费 | 27篇 |
专业分类
耳鼻咽喉 | 12篇 |
儿科学 | 47篇 |
妇产科学 | 31篇 |
基础医学 | 161篇 |
口腔科学 | 44篇 |
临床医学 | 140篇 |
内科学 | 191篇 |
皮肤病学 | 8篇 |
神经病学 | 84篇 |
特种医学 | 135篇 |
外科学 | 194篇 |
综合类 | 22篇 |
一般理论 | 1篇 |
预防医学 | 117篇 |
眼科学 | 141篇 |
药学 | 74篇 |
中国医学 | 5篇 |
肿瘤学 | 67篇 |
出版年
2021年 | 9篇 |
2019年 | 15篇 |
2018年 | 17篇 |
2017年 | 17篇 |
2016年 | 16篇 |
2015年 | 15篇 |
2014年 | 28篇 |
2013年 | 49篇 |
2012年 | 39篇 |
2011年 | 50篇 |
2010年 | 38篇 |
2009年 | 47篇 |
2008年 | 48篇 |
2007年 | 54篇 |
2006年 | 50篇 |
2005年 | 46篇 |
2004年 | 52篇 |
2003年 | 35篇 |
2002年 | 35篇 |
2001年 | 36篇 |
2000年 | 33篇 |
1999年 | 38篇 |
1998年 | 40篇 |
1997年 | 37篇 |
1996年 | 41篇 |
1995年 | 40篇 |
1994年 | 37篇 |
1993年 | 26篇 |
1992年 | 19篇 |
1991年 | 31篇 |
1990年 | 20篇 |
1989年 | 32篇 |
1988年 | 34篇 |
1987年 | 28篇 |
1986年 | 34篇 |
1985年 | 29篇 |
1984年 | 19篇 |
1983年 | 18篇 |
1982年 | 21篇 |
1981年 | 18篇 |
1980年 | 17篇 |
1979年 | 15篇 |
1978年 | 10篇 |
1977年 | 11篇 |
1976年 | 11篇 |
1975年 | 19篇 |
1973年 | 14篇 |
1972年 | 10篇 |
1969年 | 12篇 |
1968年 | 9篇 |
排序方式: 共有1474条查询结果,搜索用时 15 毫秒
21.
Bolontrade MF; Stern MC; Binder RL; Zenklusen JC; Gimenez-Conti IB; Conti CJ 《Carcinogenesis》1998,19(12):2107-2113
In this study we have analyzed the vascular response induced in the two-
stage carcinogenesis model in SENCAR mice. The role of angiogenesis has not
been explored in this model, which is the paradigm of multistage
carcinogenesis and a model for neoplastic lesions derived from exophytic
premalignant lesions (e.g. colon carcinoma, bladder papilloma). We
investigated if angiogenesis is involved in the formation of papillomas and
in the progression from papilloma to carcinoma. To this end we analyzed the
vasculature of normal and hyperplastic skin, focal epidermal hyperplasias
that are precursors of papillomas, papillomas at different stages and
squamous cell carcinomas. We also analyzed the vascularization of
papillomas induced in two strains of mice that differ in their
susceptibility to malignant progression. We show here that angiogenesis is
turned on in the earliest stages of papilloma formation. In late stages,
regardless of state of progression, the predominant response is an increase
in the size of blood vessels. Thus, in the SENCAR mouse model,
representative of exophytic tumors, the angiogenesis switch is a very early
event, probably mechanistically related to the development of the primarily
exophytic lesions. Therefore, the density of blood vessels cannot be used
as a predictor of malignant progression in this model.
相似文献
22.
We investigated the hyperalgesic (antianalgesic) effect of the inhaled anesthetics isoflurane, halothane, nitrous oxide, and diethyl ether, or the nonimmobilizer 1, 2-dichlorohexafluorocyclobutane at subanesthetic partial pressures (or, for the nonimmobilizer, subanesthetic partial pressures predicted from lipid solubility) in rats. Hyperalgesia was assessed as a decrease in the time to withdrawal of a rat hind paw exposed to heat. All four anesthetics, including nitrous oxide and diethyl ether, produced hyperalgesia at low partial pressures, with a maximal effect at 0.1 minimum alveolar anesthetic concentration (MAC) required to prevent response to movement in 50% of animals, and analgesia (an increased time to withdrawal of the hind paw) at 0. 4 to 0.8 MAC. The nonimmobilizer had neither analgesic nor hyperalgesia effects. We propose that inhaled anesthetics with a higher MAC-Awake (the MAC-fraction that suppresses appropriate responsiveness to command), such as nitrous oxide and diethyl ether, can be used as analgesics because patients are conscious at higher anesthetic partial pressures, including those which have analgesic effects, whereas anesthetics with a lower MAC-Awake do not produce analgesic effects at concentrations that permit consciousness. Implications: The inhaled anesthetics isoflurane, halothane, nitrous oxide, and diethyl ether produce antianalgesia at subanesthetic concentrations, with a maximal effect at approximately one-tenth the concentration required for anesthesia. This effect may enhance perception of pain when such small concentrations are reached during recovery from anesthesia. 相似文献
23.
24.
Vitamin A and thyroid hormone status have been shown previously to alter the toxicity of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in rats. In the present study, we have examined the effects of a vitamin A-excess and a vitamin A-deficient diet on thyroid hormone levels, on selected drug-metabolizing enzymes in liver microsomes, and on their inducibility by TCDD in male Sprague-Dawley rats. Except for a slight increase in serum T3 levels, none of these end points was affected by feeding rats the vitamin A-deficient diet. In contrast, excess dietary vitamin A caused a decrease in serum thyroxine (T4) and triiodothyronine (T3) levels, although the levels of T3 remained in the euthyroid range (60-80 ng/dl). The concentration of liver microsomal cytochromes P-450 and b5 and the basal activity of benzo[a]pyrene hydroxylase and 7-ethoxyresorufin O-de-ethylase were unaffected by excess dietary vitamin A. This result is consistent with our previous observation that the basal activity of these enzymes is dependent more on T3 than on T4 levels. Vitamin A excess markedly suppressed the activity of liver microsomal UDP-glucuronosyl transferase toward 1-naphthol. However, no such enzyme suppression was observed in thyroidectomized rats. This suggests that the suppressive effect of vitamin A on UDP-glucuronosyl transferase activity may be dependent on T3. Neither vitamin A nor thyroid status had any major effect on the inducibility of UDP-glucuronosyl transferase and cytochrome P-450-dependent enzyme activities by TCDD. However, vitamin A and TCDD had a nearly additive effect on suppression of serum T4. It is concluded that liver microsomal enzyme induction is not associated with the modulatory effect of vitamin A and thyroid hormones on the toxicity of TCDD. 相似文献
25.
26.
27.
Acute otomastoiditis and its complications: role of CT 总被引:2,自引:0,他引:2
Acute bacterial (suppurative) otomastoiditis responds to antibiotic treatment; radiologic study is required only when there is clinical suggestion of coalescent mastoiditis, intracranial complications, or an underlying chronic disease. Computed tomography (CT) is the method of choice for evaluating otogenic intra- or extra-cranial complications. CT scans can show stages of disease progression when infection has spread by way of soft tissue, blood, and bone pathways into the dural venous sinuses, meninges, labyrinth, facial nerves, epidural and other intracranial spaces. When there is clinical suggestion of acute coalescent mastoiditis, a CT scan of the temporal bone can confirm the presence of rarefying osteitis, coalescence of the air cells, and subperiosteal abscess. 相似文献
28.
TEL gene is involved in myelodysplastic syndromes with either the typical t(5;12)(q33;p13) translocation or its variant t(10;12)(q24;p13) 总被引:1,自引:0,他引:1
Wlodarska I; Mecucci C; Marynen P; Guo C; Franckx D; La Starza R; Aventin A; Bosly A; Martelli MF; Cassiman JJ 《Blood》1995,85(10):2848-2852
A t(5;12)(q33;p13) translocation is a recurrent chromosome abnormality in a subgroup of myeloid malignancies with features of both myeloproliferative disorders and myelodysplastic syndromes (MDSs). The molecular consequence of a t(5;12) is a fusion between the platelet- derived growth factor receptor-B gene on chromosome 5 and a novel ETS- like gene, TEL, on chromosome 12. We report on three patients with a t(5;12)(q33;p13) diagnosed as chronic myelomonocytic leukemia, and one case of a t(10;12)(q24;p13) in a progressive MDS, with eosinophilia and monocytosis. Involvement of the TEL gene in these chromosome translocations was investigated by fluorescence in situ hybridization (FISH) with cosmid probes containing selectively the 5' end or 3' end of TEL. Hybridization of these cosmids to the der(5)/der(10) or a der(12), respectively, demonstrated a rearrangement of TEL in both translocations, showing that the t(10;12) is a variant translocation of the t(5;12). Cloning of the fusion cDNA of one case of t(5;12) showed that the breakpoint occurred at the RNA level at exactly the same position as reported by Golub et al (Cell 77:307, 1994). In addition, the TEL gene on chromosome 12 could be localized between two probes previously mapped to 12p13, namely PRB1 and D12S178, leading to a better definition of the position of TEL in this chromosome region. Moreover, in the case involving chromosome 10, the breakpoint occurred between cKTN206 and cKTN312/LYT-10 at 10q24. Clinicohematological data in these studies as well as the restriction mapping of chromosomal breakpoints strongly suggest that (1) common features in MDSs involving the TEL gene are monocytosis and eosinophilia, (2) chromosomes other than no. 5 may be involved and at least a t(10;12)(q24;p13) variant chromosome translocation does exist in these MDSs, and (3) both standard and variant 12p/TEL translocations may be identified by FISH with appropriate probes. 相似文献
29.
BACKGROUND: This study describes the process and outcomes of continuous outpatient support with inotropes (COSI) in patients with Stage D heart failure (HF). Although Stage D HF has recently been defined as end-stage disease requiring special interventions for survival such as COSI or ventricular assist devices, concern has been raised regarding the safety, efficacy, mortality outcomes, and ethics of COSI. METHODS AND RESULTS: Inotrope dependence was defined as worsening of the patient's clinical status with attempted inotrope withdrawal such that the patient was deemed unlikely to survive to permit hospital discharge. A care process for COSI was designed; baseline and outcome variables were evaluated. COSI was administered to 36 inotrope-dependent patients (age 55.4 +/- 9.5 years, 24 males). Baseline characteristics (mean +/- SD) were consistent with Stage D HF: left ventricular ejection fraction 19.9 +/- 8.5, left ventricular end-diastolic dimension (LVEDD) 70 +/- 10 mm, systolic blood pressure 97.4 +/- 13.4 mm Hg, serum creatinine 1.5 +/- 0.6, serum sodium 131.7 +/- 5.3; 69 HF hospitalizations (mean 1.9 +/- 1.8) 6 months before COSI initiation. Symptomatic hypotension, increasing dyspnea, renal dysfunction, and hypoperfusion most commonly prevented inotrope withdrawal. Despite Stage D HF, patients were discharged with COSI ambulatory, oriented, and pain free. Rehospitalizations were 46; 6 subjects accounted for 24 hospitalizations; 23 had 0 or 1 rehospitalization. Median survival was 3.4 months (range 0.2-26.3 months); and 3-, 6-, and 12-month Kaplan Meier survival was 51%, 26%, and 6%, respectively. The majority of patients died at home and chose to not undergo resuscitation attempts. CONCLUSION: COSI may be an acceptable treatment option for Stage D HF. 相似文献
30.
Hepatosplenic T-cell lymphoma: sinusal/sinusoidal localization of malignant cells expressing the T-cell receptor gamma delta 总被引:12,自引:0,他引:12
Farcet JP; Gaulard P; Marolleau JP; Le Couedic JP; Henni T; Gourdin MF; Divine M; Haioun C; Zafrani S; Goossens M 《Blood》1990,75(11):2213-2219
Peripheral T-cell lymphomas consist of a clinically heterogeneous group of malignant disorders whose immunophenotype usually corresponds to that of normal mature T cells. We describe and correlate the clinical, histopathologic, phenotypic, and genotypic findings in two patients with malignant lymphoma presenting with hepatosplenic disease. The morphologic pattern of lymphoma was that of a sinusal/sinusoidal infiltration in spleen, marrow, and liver. This morphologic characteristic was associated with the presence of a productive clonal rearrangement of the T-cell receptor (TCR) delta gene. Lymphoma cells expressed a CD3-TCR-gamma delta- phenotype. They were also double negative (ie, CD4-CD8-) and lacked the CD5 and CD7 antigens. In one patient, tumor progression was associated with phenotypic changes that resulted in a CD3-TCR-gamma delta- phenotype with the same delta-gene rearrangement as initially. These observations suggest the existence of a new type of peripheral T-cell lymphoma characterized by its hepatosplenic presentation, and by the sinusal/sinusoidal tropism and the TCR-gamma delta phenotype of the malignant cells. 相似文献