全文获取类型
收费全文 | 33601篇 |
免费 | 1887篇 |
国内免费 | 297篇 |
专业分类
耳鼻咽喉 | 558篇 |
儿科学 | 682篇 |
妇产科学 | 871篇 |
基础医学 | 5544篇 |
口腔科学 | 1013篇 |
临床医学 | 2940篇 |
内科学 | 6301篇 |
皮肤病学 | 865篇 |
神经病学 | 3050篇 |
特种医学 | 1445篇 |
外科学 | 4273篇 |
综合类 | 1045篇 |
一般理论 | 4篇 |
预防医学 | 1843篇 |
眼科学 | 874篇 |
药学 | 2602篇 |
4篇 | |
中国医学 | 219篇 |
肿瘤学 | 1652篇 |
出版年
2023年 | 168篇 |
2022年 | 305篇 |
2021年 | 509篇 |
2020年 | 377篇 |
2019年 | 425篇 |
2018年 | 503篇 |
2017年 | 474篇 |
2016年 | 507篇 |
2015年 | 672篇 |
2014年 | 775篇 |
2013年 | 1069篇 |
2012年 | 1502篇 |
2011年 | 1767篇 |
2010年 | 1190篇 |
2009年 | 1100篇 |
2008年 | 1558篇 |
2007年 | 1751篇 |
2006年 | 1633篇 |
2005年 | 1571篇 |
2004年 | 1504篇 |
2003年 | 1437篇 |
2002年 | 1430篇 |
2001年 | 789篇 |
2000年 | 754篇 |
1999年 | 726篇 |
1998年 | 420篇 |
1997年 | 408篇 |
1996年 | 318篇 |
1995年 | 251篇 |
1994年 | 276篇 |
1993年 | 217篇 |
1992年 | 404篇 |
1991年 | 389篇 |
1990年 | 340篇 |
1989年 | 325篇 |
1988年 | 309篇 |
1987年 | 268篇 |
1986年 | 270篇 |
1985年 | 280篇 |
1984年 | 194篇 |
1983年 | 187篇 |
1982年 | 156篇 |
1979年 | 163篇 |
1978年 | 150篇 |
1975年 | 156篇 |
1932年 | 141篇 |
1931年 | 138篇 |
1930年 | 166篇 |
1928年 | 149篇 |
1926年 | 138篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
K. Dahan V. Audard F. Roudot-Thoraval D. Desvaux M. Abtahi H. Mansour M. Kumal P. Lang P. Grimbert 《American journal of transplantation》2006,6(7):1725-1730
The clinical outcome and appropriate management for patients showing 'borderline changes' on allograft biopsy after renal transplantation is still controversial. In an attempt to identify predictive factors of clinical outcome of patients with such lesions, we reviewed the clinical course of 91 patients with borderline changes. Multivariate analysis revealed significant and independent effects of histological stage (i + t < or = or > 2) and time to borderline changes (< or = or > 3 months after transplant) on serum creatinine levels at 1 year from borderline changes episodes (respectively, p = 0.04 and p = 0.02) and only a significant effect of time to borderline changes on serum creatinine levels at 2 years (p = 0.005). Renal function at 1 year and 2 years as 5- and 8-year graft survival were not significantly different in the group of patients treated with antirejection therapy (T group, n = 49) compared with the untreated group (UT group, n = 42). This study strongly suggests that borderline changes with histological score (i + t) > 2 and late episodes of borderline changes should be considered to be of poor prognosis. 相似文献
2.
3.
Lisa A. Lang DDS MS David C. Holmes DDS MS Craig Passon DDS MS Robert M. Trombly DDS JD Jeffrey D. Astroth DDS MSPH Arnold F. Tavel DMD 《Journal of prosthodontics》2003,12(3):206-210
Using complete denture treatment as an introduction to clinical patient care for dental students, the purposes of the Complete Denture Prosthodontics Transition Clinic at the University of Colorado School of Dentistry are to reduce the time lapse between the preclinical complete denture prosthodontics course and the first denture patient experience, and to encourage development of student self-confidence and skills. In the 2002 spring semester, faculty at the University of Colorado School of Dentistry initiated the Complete Denture Prosthodontics Transition Clinic for DS-II (second-year) dental students, as an introduction to clinical patient care. Each patient was assigned to a team of two dental students. Three Division of Prosthodontics faculty members staffed each clinic session, providing a student-to-faculty ratio of approximately 6.6:1 and a patient-to-faculty ratio of approximately 3.3:1. All DS-II students in the Class of 2004 delivered their first complete dentures no later than 8 months (average, 184 days) after the last day of the preclinical complete denture prosthodontics course. The time from the diagnostic appointment through the denture placement appointment averaged 39 days for patients treated in this program, compared with an average of 98 days or more for previous classes. The program was successful in achieving the goal of reducing the time lapse between the preclinical complete denture prosthodontics course and the first denture patient experience. 相似文献
4.
W. Nörenberg Ernst Schöffel Bela Szabo Klaus Starke 《Naunyn-Schmiedeberg's archives of pharmacology》1997,356(2):159-165
The aim of the study was to subclassify the soma-dendritic α2-autoreceptors in the locus coeruleus (LC) of the rat by means of antagonists. To this end, the frequency of spontaneous action
potentials was recorded extracellularly from single LC neurones in brain slices. The neurones fired spontaneously at an average
rate of 1 Hz. The selective α2-adrenoceptor agonist 5-bromo-6-(2-imidazolin-2-ylamino)-quinoxaline (UK 14,304) and noradrenaline decreased the action potential
discharge with IC50 values of 5 and 510 nM, respectively. The concentration-inhibition curves of UK 14,304 and noradrenaline were shifted to the
right by phentolamine (0.15 μM) and rauwolscine (0.15 μM) but not by prazosin (1 μM). Apparent K
d values of phentolamine were 17 nM (against UK 14,304) and 20 nM (against noradrenaline). Apparent K
d values of rauwolscine were 47 nM (against UK 14,304) and 70 nM (against noradrenaline). (+)-Oxaprotiline (1 μM) suppressed
the firing of the neurones within 10 to 33 min. In the continued presence of oxaprotiline, phentolamine and rauwolscine restored
firing with EC50 values of 120 and 250 nM, respectively. Prazosin (1 μM) again was ineffective. All three antagonist affinity estimates –
against UK 14,304, exogenous noradrenaline and endogenous noradrenaline (that accumulates in the extracellular space in the
presence of oxaprotiline) – yield an affinity order phentolamine > rauwolscine >> prazosin, prazosin being ineffective even
at a concentration of 1 μM. These findings identify the soma-dendritic α2-autoreceptors of the LC as the rat variant of the α2A/D-adrenoceptor, i.e. α2D. Not only presynaptic but also soma-dendritic α2-autoreceptors may at least predominantly be α2A/D throughout the nervous system.
Received: 3 March 1997 / Accepted: 21 April 1997 相似文献
5.
The possible reversal by calcium of the inhibitory action of verapamil on the atrioventricular (AV) node was investigated in anesthetized, atropinized dogs, with cardiac pacing. The His bundle potentials were recorded by endocavitory electrode and the AV node effective refractory period measured by the extrastimulus method. Calcium infusion was effective against the impairment of AV nodal conduction induced by verapamil, provided it remained moderate: the gradual rise in the plasma calcium concentration counteracted the effects of an infusion of verapamil on conduction time and effective refractory period in the AV node, as long as it did not exceed 5 mmol/L. However, beyond this level, calcium appeared less and less capable of reversing the effects of verapamil. Thus, the protective action of calcium had a bell-shaped dose-response curve, with the optimum at 5 mmol/L. This biphasic influence is consistent with the opposite opinions previously given concerning the antagonism between calcium and calcium blockers, depending on whether hypercalcemia brought into play was mild or major. In any case, the prominent role played by calcium in the slow inward current in the AV node accounts for the antagonism, observed in vivo, between calcium and verapamil. The pacemaker activity of the sinoatrial (SA) node was less influenced by both calcium blocker and calcium. 相似文献
6.
Frank Lindseth Thomas Lang? Jon Bang Toril A Nagelhus Hernes 《Computer aided surgery》2002,7(4):197-222
7.
8.
9.
Johannes Woitzik Elke Lassel Ulf C. Schneider Helmut Schroeck Rudolf Graf 《Experimental neurology》2009,218(1):41-350
Lesion evolution during focal cerebral ischemia may depend on flow restrictions or on accumulation of toxic mediators within the infarct and expansion of these factors to the periinfarct region. So far, the precise contribution of flow dependent versus spreading-mediated impairment of viable periinfarct tissue has not been determined. Therefore, we measured lesion expansion, flow restrictions and glutamate distribution on serial brain sections at different time points after experimental focal ischemia.Permanent focal ischemia was induced by occlusion of the right middle cerebral artery in male rats and the flow reduction was subsequently measured at 1, 12 and 24 h using iodo[14C]antipyrine autoradiography. Additionally, the necrotic volume was determined on serial brain sections and the glutamate content was measured in tissue samples from adjacent microdissections.Twelve hours after focal ischemia no noteworthy viable areas with blood flow restrictions of 20-40 ml 100 g− 1 min− 1 existed but at 24 h the necrotic tissue exceeded the hemodynamically compromised region by 40 ± 21 mm3 (24%). Furthermore, at 12 and 24 h the glutamate content was elevated in areas surrounding the infarct.Relevant flow restrictions are detectable only during early stages of infarct maturation, whereas the propagation of secondary factors may be the predominant mechanism for delayed infarct evolution. 相似文献
10.