全文获取类型
收费全文 | 4527篇 |
免费 | 362篇 |
国内免费 | 57篇 |
专业分类
耳鼻咽喉 | 35篇 |
儿科学 | 135篇 |
妇产科学 | 75篇 |
基础医学 | 449篇 |
口腔科学 | 162篇 |
临床医学 | 611篇 |
内科学 | 718篇 |
皮肤病学 | 159篇 |
神经病学 | 250篇 |
特种医学 | 272篇 |
外科学 | 440篇 |
综合类 | 380篇 |
一般理论 | 4篇 |
预防医学 | 406篇 |
眼科学 | 38篇 |
药学 | 419篇 |
3篇 | |
中国医学 | 101篇 |
肿瘤学 | 289篇 |
出版年
2022年 | 41篇 |
2021年 | 62篇 |
2020年 | 63篇 |
2019年 | 55篇 |
2018年 | 45篇 |
2017年 | 74篇 |
2016年 | 56篇 |
2015年 | 69篇 |
2014年 | 97篇 |
2013年 | 156篇 |
2012年 | 206篇 |
2011年 | 220篇 |
2010年 | 150篇 |
2009年 | 159篇 |
2008年 | 215篇 |
2007年 | 210篇 |
2006年 | 213篇 |
2005年 | 188篇 |
2004年 | 158篇 |
2003年 | 109篇 |
2002年 | 116篇 |
2001年 | 118篇 |
2000年 | 99篇 |
1999年 | 99篇 |
1998年 | 67篇 |
1997年 | 72篇 |
1996年 | 80篇 |
1995年 | 56篇 |
1994年 | 52篇 |
1993年 | 53篇 |
1992年 | 82篇 |
1991年 | 94篇 |
1990年 | 85篇 |
1989年 | 79篇 |
1988年 | 72篇 |
1987年 | 63篇 |
1986年 | 56篇 |
1985年 | 70篇 |
1984年 | 60篇 |
1983年 | 43篇 |
1982年 | 36篇 |
1981年 | 36篇 |
1979年 | 52篇 |
1977年 | 32篇 |
1959年 | 42篇 |
1958年 | 66篇 |
1957年 | 77篇 |
1956年 | 73篇 |
1955年 | 84篇 |
1954年 | 51篇 |
排序方式: 共有4946条查询结果,搜索用时 31 毫秒
61.
62.
1. The vasoconstrictor responses of isolated intrapulmonary arteries (IPA) to P2-receptor agonists was investigated during adaptation to extrauterine life in the normal piglet and the effect of pulmonary hypertension was studied following exposure of newborn animals to chronic hypobaric hypoxia (51 kPa) for 3 days. 2. At resting tone, alpha,beta-methyleneATP (alpha,beta-meATP) (P2X-receptor agonist) contracted intrapulmonary arteries from adult, but not immature pigs, and repeated application desensitized the response. 3. Adenosine 5'-triphosphate (ATP) induced endothelium-independent relaxation at low concentrations at all ages, a variable contractile response to high concentrations developed by 3 days, becoming larger and consistent by 14 days of age. 4. Uridine 5'-triphosphate (UTP) evoked a contractile response in normal intrapulmonary arteries from foetal to adult life, the magnitude of the response increasing with age. Endothelial removal and pre-incubation with Nomega-nitro-L-arginine methyl ester (L-NAME) (100 microM) increased the contractile response of adult vessels. 5. Pre-incubation with alpha,beta-meATP (100 microM), increased the contractile response to UTP in both newborn and adult vessels. ATP-induced relaxations were reduced in newborn vessels but there was no effect on the responses of adult vessels. 6. Responses to UTP, ATP and alpha,beta-meATP of intrapulmonary arteries from newborn piglets exposed to chronic hypobaric hypoxia for 3 days were normal. 7. In summary, UTP elicited marked vasoconstriction of porcine IPA at all ages. UTP and ATP responses were consistent with activation of the P2Y4-receptor recently identified in vascular smooth muscle by others. alpha, beta-meATP induced a small vasoconstriction in the adult probably via the P2X1-receptor. Responses remained normal in neonatal pulmonary hypertension. 相似文献
63.
Evaluation of formulae for CSF IgG synthesis using data obtained from two methods: importance of receiver operator characteristic curve analysis. 下载免费PDF全文
AIMS: To determine the clinical performance of three cerebrospinal fluid (CSF) IgG synthesis formulae using data obtained from two quantitation methods. METHODS: Receiver operator characteristic (ROC) analysis and decision index plots were used to compare a rate nephelometric (RN) and a rocket immunoelectrophoretic (RIEP) method for quantitating albumin and IgG for use in CSF IgG synthesis formulae. Further analysis was used to determine the most clinically accurate of these formulae for a diagnosis of multiple sclerosis with regard to technical accuracy and cost effectiveness. RESULTS: Values for albumin and IgG determined by RN gave better sensitivities and specificities than the RIEP method when applied to all three formulae; however, when the 95% confidence limits were considered, the difference was not significant. Using the RN method with an agreed "rule in" threshold value of 90% specificity, the IgG index gave the best clinical performance. CONCLUSION: ROC curve analysis and decision index plots provide valuable tools in assessing and comparing the clinical performance of new and existing laboratory assays. 相似文献
64.
In a drug discrimination paradigm pigeons and rats were trained with an operant procedure to discriminate between the presence and absence of the effects of 9-THC (1.0 and 3.0 mg/kg, injected IM 90 min and I.P. 30 min before the start of the session). Once trained, various THC metabolites as well as a water-soluble derivative of THC (SP-111), were substituted for 9-THC to test for generalization to the training drug. Generalization to 9-THC occurred with the 11-hydroxy metabolites and the potency order was 11-OH-9-THC >11-OH-8-THC 9-THC. Among the other metabolites tested (8-OH-9-THC, 8, 11-di-OH-9-THC, 8-OH-9-THC, 8, 11-di-OH-9-THC), it was only 11-di-OH-9-THC that completely substituted for 9-THC in pigeons, albeit at very high dose levels (rats were not tested with these metabolites). SP-111 generalized to 9-THC in both species. However, the onset of action of SP-111 was slower than that for 9-THC, especially in pigeons. These studies show the importance of obtaining complete dose-effect determinations over time when assessing structure-activity relationships with drug-discrimination procedures.A brief account of the results, which are summarized in Neuropharmacology 18:1023–1024, 1979), was presented at the British Association for Psychopharmacology Summer Conference, July 15–17, Birmingham, England, 1979 相似文献
65.
We report here a patient with acute mycloid leukaemia who relapsed 20 months after undergoing a double autograft procedure in first remission. He was reinduced and subsequently underwent a third autologous bone marrow transplantation in second remission using bone marrow harvested in second remission and a Busulphan and Cyclophosphamide conditioning regimen. Although the engraftment was very slow, he has remained in second remission for 34+ months. This case demonstrates that durable disease-free survival can be attained by a second preparative therapy, even in second remission, for patients relapsed after autologous bone marrow transplantation. 相似文献
66.
Euan M. McMillan B.Sc. M.B. M.R.C.P. Rose Wasik H.T. Mark Allen Everett M.D. 《Journal of the American Academy of Dermatology》1982,6(1):32-39
It has been demonstrated recently in mycosis fungoides and lichen planus that T lymphocyte subsets may be identified in cutaneous lymphocytic infiltrates using the immunoperoxidase technic in conjunction with monoclonal antibodies produced by the technic of Kohler and Milstein. This communication describes the application of this technic to cutaneous lymphoid infiltrates of parapsoriasis in which T cell predominance has been demonstrated previously. The lymphoid infiltrates of six patients with atrophic parapsoriasis were examined by the indirect immunoperoxidase technic using monoclonal antibodies (from two commercial sources) directed against "helper" and "suppressor" T cell subsets. Both "helper" and "suppressor" cells (as defined by a positive reaction with monoclonal antibodies) could be identified in cutaneous infiltrates. "Helper" cells predominated, but in varying degrees among patients. The relevance of these findings in relation to the possible development of clinical mycosis fungoides from atrophic parapsoriasis is discussed. In addition, factors causing difficulty in the consistent identification of cell subtypes are discussed. These factors suggest that in the present state of imperfection, difficulty will be experienced in using this technic for the accurate quantification of percentages of lymphocyte subsets in tissue sections.U 相似文献
67.
Pigeons responding under a variable-interval (VI) 75-s schedule of food presentation were used to study cross-tolerance from 9-tetrahyrocannabinol (9-THC) to pentobarbital and barbital. After initial dose-effect functions for pentobarbital and barbital were determined, the birds received 9-THC injections for 6 weeks. This chronic administration regimen resulted in a greater than 100-fold tolerance to 9-THC. Redetermination of the pentobarbital and barbital dose-effect functions during the chronic 9-THC regimen revealed statistically significant shifts to the right for the pentobarbital (0.191 log unit) and barbital (0.078 log unit) dose-effect curves. All six birds showed tolerance to pentobarbital, while four of the six showed tolerance to barbital. Blood barbital levels before and after chronic 9-THC administration did not differ significantly. Tolerance to 9-THC was more prolonged and of much greater magnitude than the cross-tolerance to pentobarbital or barbital. The results demonstrate that cross-tolerance can develop from 9-THC to a barbiturate that normally undergoes little metabolism. 相似文献
68.
高效液相色谱法测定绿茶和饮料中的咖啡因 总被引:5,自引:0,他引:5
采用反相高效液相色谱法,固定相为十八烷基硅烷键合硅胶,以乙腈-水(20:80)为流动相,检测波长274nm,测定绿茶和饮料中的咖啡因含量。结果线性范围为3.9~3900ng,r=O.9999;绿茶和2种饮料的平均加样回收率分别为100.2%、100.1%和99.8%。该方法准确、简便、快速,适合绿茶和可乐型饮料中咖啡因的测定。 相似文献
69.
70.
A Correlational Test of the Relationship Between Posttraumatic Growth,Religion, and Cognitive Processing 总被引:5,自引:0,他引:5
The present study examined the degree to which event related rumination, a quest orientation to religion, and religious involvement is related to posttraumatic growth. Fifty-four young adults, selected based on prescreening for experience of a traumatic event, completed a measure of event related ruminations, the Quest Scale, an index of religious participation, and the Posttraumatic Growth Inventory. The three subscales of the Quest Scale, the two groups of rumination items (soon after event/within past two weeks), and the index of religious participation were entered in a standard multiple regression with the total score of the Posttraumatic Growth Inventory as the dependent variable. The degree of rumination soon after the event and the degree of openness to religious change were significantly related to Posttraumatic Growth. Congruent with theoretical predictions, more rumination soon after the event, and greater openness to religious change were related to more posttraumatic growth. Present findings offer some confirmation of theoretical predictions, and also offer clear direction for further research on the relationships of religion, rumination, and posttraumatic growth. 相似文献