全文获取类型
收费全文 | 1641篇 |
免费 | 115篇 |
国内免费 | 7篇 |
专业分类
耳鼻咽喉 | 5篇 |
儿科学 | 127篇 |
妇产科学 | 55篇 |
基础医学 | 258篇 |
口腔科学 | 9篇 |
临床医学 | 93篇 |
内科学 | 241篇 |
皮肤病学 | 25篇 |
神经病学 | 108篇 |
特种医学 | 14篇 |
外科学 | 309篇 |
综合类 | 122篇 |
预防医学 | 83篇 |
眼科学 | 16篇 |
药学 | 143篇 |
中国医学 | 5篇 |
肿瘤学 | 150篇 |
出版年
2022年 | 20篇 |
2021年 | 51篇 |
2020年 | 25篇 |
2019年 | 30篇 |
2018年 | 35篇 |
2017年 | 23篇 |
2016年 | 31篇 |
2015年 | 22篇 |
2014年 | 34篇 |
2013年 | 39篇 |
2012年 | 78篇 |
2011年 | 92篇 |
2010年 | 64篇 |
2009年 | 65篇 |
2008年 | 71篇 |
2007年 | 78篇 |
2006年 | 61篇 |
2005年 | 54篇 |
2004年 | 37篇 |
2003年 | 36篇 |
2002年 | 54篇 |
2001年 | 42篇 |
2000年 | 23篇 |
1999年 | 33篇 |
1998年 | 11篇 |
1997年 | 12篇 |
1995年 | 17篇 |
1994年 | 17篇 |
1993年 | 16篇 |
1992年 | 27篇 |
1991年 | 36篇 |
1990年 | 25篇 |
1989年 | 32篇 |
1988年 | 25篇 |
1987年 | 22篇 |
1986年 | 36篇 |
1985年 | 18篇 |
1984年 | 19篇 |
1983年 | 17篇 |
1982年 | 10篇 |
1981年 | 9篇 |
1979年 | 16篇 |
1975年 | 15篇 |
1974年 | 19篇 |
1973年 | 12篇 |
1972年 | 10篇 |
1971年 | 13篇 |
1970年 | 16篇 |
1966年 | 10篇 |
1958年 | 8篇 |
排序方式: 共有1763条查询结果,搜索用时 15 毫秒
101.
Bose J 《The journal of the American Academy of Psychoanalysis and Dynamic Psychiatry》2005,33(1):51-70
The role of art in the encounter with trauma and destructiveness is comparatively studied in the works of Frida Kahlo and Francis Bacon as examples of a direct and a more indirect way of dealing with such experiences. A creative product may function intrapsychically as a kind of messenger between dissociated self-states and consciousness, and it may also serve as a witnessing presence in a self-supporting and self-constituting way. Artistic work may thus be used by the artist for an expressive as well as for a protective purpose, as a means of sympathetic participation in painful experience, or as a medium for a view from the outside. The act itself of finding and of making expressive forms at the time of traumatic experience is a remarkable assertion of the human capability to synthesize and to counteract fragmenting dissociative processes. 相似文献
102.
Heparin and aspirin attenuate placental apoptosis in vitro: implications for early pregnancy failure
Bose P Black S Kadyrov M Weissenborn U Neulen J Regan L Huppertz B 《American journal of obstetrics and gynecology》2005,192(1):23-30
OBJECTIVE: Live birth rates are increased by treatment with heparin and aspirin in cases of poor pregnancy outcome such as antiphospholipid syndrome. Both drugs may attenuate miscarriage by inhibiting aberrant coagulation or by modulating trophoblast apoptosis. Here we assessed their roles in trophoblast apoptosis in vitro. STUDY DESIGN: BeWo cells and placental villi were cultured in sera from women with successful or failing in vitro fertilization, with and without heparin or aspirin. Apoptosis was assessed by using DNA laddering, cytokeratin 18 neoepitope formation, Bcl-2, and caspase 7 expression. RESULTS: In BeWo cells, sera from in vitro fertilization failure increased trophoblast apoptosis, whereas heparin and aspirin reversed these effects. In villous trophoblast, heparin increased Bcl-2 and cytokeratin 18 protein expression. Heparin and aspirin inhibited DNA laddering. CONCLUSION: Heparin and aspirin modulate trophoblast apoptosis suggesting a direct impact on trophoblast biology, thus providing an additional mechanism to explain the clinical benefits of heparin and aspirin on recurrent pregnancy loss. 相似文献
103.
Morphological changes of the soleus motoneuron pool in chronic midthoracic contused rats 总被引:1,自引:0,他引:1
This study investigated the morphological features of the soleus motoneuron pool in rats with chronic (4 months), midthoracic (T8) contusions of moderate severity. Motoneurons were retrogradely labeled using unconjugated cholera toxin B (CTB) subunit solution injected directly into the soleus muscle of 10 contused and 6 age- and sex-matched, normal controls. Morphometric studies compared somal area, perimeter, diameter, dendritic length, and size distribution of labeled cells in normal and postcontusion animals. In normal animals, motoneurons with a mean of 110.4 +/- 5.2 were labeled on the toxin-injected side of the cord (left). By comparison, labeled cells with a mean of 93.0 +/- 8.4 (a 16% decrease, P = 0.006) were observed in the chronic spinal-injured animals. A significantly smaller frequency of very small (area, approximately 100 microm2) and medium (area, 545-914 microm2) neurons, and a significantly higher frequency of larger (area, >914 microm2) neurons was observed in the labeled soleus motoneuron pools of injured animals compared with the normal controls. Dendritic bundles in the contused animals were composed of thicker dendrites, were arranged in more closely aggregated bundles, and were organized in a longitudinal axis (rostrocaudal axis). Changes in soleus motoneuron dendritic morphology also included significant decrease of total number of dendrites, increased staining, hypertrophy of primary dendrites, and significant decreased primary, secondary, and tertiary branching. The changes in size distribution and dendritic morphology in the postcontusion animals possibly resulted from cell loss and transformation of medium cells to larger cells and/or injury-associated failure of medium cells to transport the immunolabel. 相似文献
104.
105.
PURPOSE OF REVIEW: The ductus arteriosus is a vessel that connects the pulmonary artery to the aorta and provides a pulmonary-to-systemic diversion during fetal life. In the vast majority of infants, the ductus arteriosus closes by 3 days of life. In some infants, especially preterm infants with lung disease, there is delayed closure of the ductus arteriosus. There has been controversy as to whether or when the ductus arteriosus should be closed by either pharmacologic or surgical methods. RECENT FINDINGS: There have been several epidemiologic studies describing an association between a patent ductus arteriosus and the development of morbidities, such as chronic lung disease. These associations have suggested to some that a causal relationship exists between patency of the ductus arteriosus and chronic lung disease and other morbidities. However, recent metaanalyses of randomized, controlled trials of the use of indomethacin for the prevention and treatment of the patent ductus arteriosus have not documented a decrease in the incidence of these morbidities after treatment, despite success in closure of the patent ductus arteriosus. SUMMARY: In preterm infants, patency of the ductus arteriosus may represent a normal physiologic adaptation to allow shunting from either systemic-to-pulmonary circulation (eg, in the first day of life) or from pulmonary-to-systemic circulation (eg, in the presence of severe lung disease). Therapies designed to close the ductus arteriosus are contraindicated in some settings and should not be considered a standard of care at any time until these therapies are proven to decrease long-term clinical morbidities in randomized, placebo-controlled trials. 相似文献
106.
107.
108.
BACKGROUND: Current guidelines for antidepressant use recommend 4 to 6 months of continuation treatment to prevent relapse of depression following symptom resolution. This study evaluates the efficacy and safety of continuation escitalopram treatment. METHOD: Outpatients diagnosed with DSM-IV major depressive disorder (male or female, aged 18 to 81 years) who had completed 8 weeks of randomized double-blind treatment with escitalopram, citalopram, or placebo entered an 8-week flexible-dose, open-label phase in which all patients received escitalopram (10-20 mg/day). This study was initiated November 3, 1999, and completed April 5, 2001. Patients who met responder criteria (score of < or = 12 on the Montgomery-Asberg Depression Rating Scale [MADRS]) were randomly assigned in a 2:1 ratio to escitalopram (at the dose each patient was receiving at the end of the open-label phase) or placebo for 36 weeks of double-blind treatment. The primary efficacy variable was time to depression relapse (defined as MADRS score > or = 22 or discontinuation due to an insufficient therapeutic response) from the start of the double-blind treatment phase. RESULTS: A total of 502 patients received open-label escitalopram treatment and had at least 1 MADRS assessment. A total of 274 evaluable subjects entered the double-blind treatment phase; 93 received placebo and 181 received escitalopram. Time to depression relapse was significantly longer (p =.013) and the cumulative rate of relapse was significantly lower in patients who received escitalopram (26% escitalopram vs. 40% placebo; hazard ratio = 0.56; p =.01). Escitalopram-treated subjects had significantly lower depression ratings than those of placebo-treated patients. Escitalopram continuation treatment was safe and well tolerated. Discontinuation rates due to adverse events were 7% for the placebo group and 4% for the escitalopram-treated group. CONCLUSION: Continuation treatment with escitalopram is effective in preventing relapse into an episode of major depressive disorder. 相似文献
109.
Contribution of synaptic depression to phase maintenance in a model rhythmic network 总被引:2,自引:0,他引:2
In many rhythmic neuronal networks that operate in a wide range of frequencies, the time of neuronal firing relative to the cycle period (the phase) is invariant. This invariance suggests that when frequency changes, firing time is precisely adjusted either by intrinsic or synaptic mechanisms. We study the maintenance of phase in a computational model in which an oscillator neuron (O) inhibits a follower neuron (F) by comparing the dependency of phase on cycle period in two cases: when the inhibitory synapse is depressing and when it is nondepressing. Of the numerous ways of changing the cycle period, we focus on three cases where either the duration of the active state, the inactive state, or the duty cycle of neuron O remains constant. In each case, we measure the phase at which neuron F fires with respect to the onset of firing in neuron O. With a nondepressing synapse, this phase is generally a monotonic function of cycle period except in a small parameter range in the case of the constant inactive duration. In contrast, with a depressing synapse, there is always a parameter regime in which phase is a cubic function of cycle period: it decreases at short cycle periods, increases in an intermediate range, and decreases at long cycle periods. This complex shape for the phase-period relationship arises because of the interaction between synaptic dynamics and intrinsic properties of the postsynaptic neuron. By choosing appropriate parameters, the cubic shape of the phase-period curve results in a small variation in phase for a large interval of periods. Consequently, we find that although a depressing synapse does not produce perfect phase maintenance, in most cases it is superior to a nondepressing synapse in promoting a constant phase difference. 相似文献
110.
Urinary tract injury in pelvic surgery 总被引:4,自引:0,他引:4