全文获取类型
收费全文 | 10014篇 |
免费 | 756篇 |
国内免费 | 227篇 |
专业分类
耳鼻咽喉 | 70篇 |
儿科学 | 166篇 |
妇产科学 | 235篇 |
基础医学 | 664篇 |
口腔科学 | 92篇 |
临床医学 | 1585篇 |
内科学 | 718篇 |
皮肤病学 | 48篇 |
神经病学 | 567篇 |
特种医学 | 151篇 |
外科学 | 991篇 |
综合类 | 2115篇 |
预防医学 | 1115篇 |
眼科学 | 65篇 |
药学 | 1443篇 |
37篇 | |
中国医学 | 665篇 |
肿瘤学 | 270篇 |
出版年
2024年 | 51篇 |
2023年 | 147篇 |
2022年 | 294篇 |
2021年 | 408篇 |
2020年 | 496篇 |
2019年 | 278篇 |
2018年 | 253篇 |
2017年 | 370篇 |
2016年 | 392篇 |
2015年 | 367篇 |
2014年 | 770篇 |
2013年 | 684篇 |
2012年 | 873篇 |
2011年 | 774篇 |
2010年 | 646篇 |
2009年 | 506篇 |
2008年 | 444篇 |
2007年 | 458篇 |
2006年 | 418篇 |
2005年 | 340篇 |
2004年 | 251篇 |
2003年 | 256篇 |
2002年 | 214篇 |
2001年 | 150篇 |
2000年 | 117篇 |
1999年 | 114篇 |
1998年 | 79篇 |
1997年 | 60篇 |
1996年 | 66篇 |
1995年 | 59篇 |
1994年 | 65篇 |
1993年 | 42篇 |
1992年 | 37篇 |
1991年 | 49篇 |
1990年 | 43篇 |
1989年 | 44篇 |
1988年 | 41篇 |
1987年 | 27篇 |
1986年 | 45篇 |
1985年 | 38篇 |
1984年 | 37篇 |
1983年 | 14篇 |
1982年 | 20篇 |
1981年 | 32篇 |
1980年 | 17篇 |
1979年 | 21篇 |
1978年 | 16篇 |
1977年 | 17篇 |
1976年 | 23篇 |
1973年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
There are a number of reports suggesting an association between profusion of eye movements and active dreaming. It has however been suggested that this relationship might only be evident in comparisons across the night and would not be evident in comparisons within one REM period. Data from 20 subjects taking placebo, amylobarbitone, and nitrazepam were used to test this. Dream reports were collected from REM awakenings and rated blind as visually active or passive. Eye movement profusion (number of 2 sec epochs) was assessed for each REM period. Correlation between dream content and eye movement was low but significant in comparisons including the whole night, and including data from drug, withdrawal, and placebo conditions. A significant correlation was not consistently obtained, however, when data from each REMP were considered separately. Correlations based on data from non-drug nights only were also small and could have been due to chance effects alone. The low correlations were not explicable solely by poor reliability of content ratings. It is concluded that the relationship between visually active dreaming and eye movement is slight, and may not hold when time of night is adequately controlled. 相似文献
52.
53.
The vulnerability of epidemic process during the period of minimum annual incidence of the disease is validated. Biological properties of Shigella sonnei are studied and their variability examined using the index for evaluation of the mean number of variations for a sign. Minimum agent heterogeneity coincides with minimum incidence of disease and maximum heterogeneity with its seasonal rises. 相似文献
54.
Kimiskidis VK Papagiannopoulos S Sotirakoglou K Kazis DA Kazis A Mills KR 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》2005,163(1):21-31
Silent period (SP) is widely used in transcranial magnetic stimulation studies. Methodologically, SP is usually elicited at stimulus intensities corresponding to a certain percentage of corticomotor threshold. Because this approach might lead to factitious SP changes, the present study was designed to develop, in a stepwise manner, a method for investigating SP independently of corticomotor threshold. First, stimulus–response (S–R) curves of SP against stimulus intensity (SI) were constructed and quantitatively described in healthy volunteers. Second, various methodological issues such as the optimum model for describing the relationship between SP duration and SI and the importance of the type of stimulating coil were addressed. Finally, the proposed method and a commonly used method (eliciting SPs at 130% MT SI) were directly compared for a group of epileptic patients for whom administration of oxcarbazepine resulted in significant corticomotor threshold elevation. Twenty-one subjects (eleven females, median age, 38 years) were studied. SPs were obtained with a figure-of-eight coil using a standardized procedure (recording, FDI). Pilot experiments indicated that at least four trials were required, at each intensity level, to estimate the mean SP duration within 10% of the true mean. Therefore, SPs were determined from the average of four trials with 5% increments from 5 to 100% maximum SI. In a second set of experiments, SPs were obtained for fifteen subjects using a circular coil. In a third set of experiments, eight epileptic patients were studied before and after administration of oxcarbazepine (mean dose 1553 mg, range 900–1800 mg). The S–R curves were fitted to a Boltzman function and to first-order to fourth-order polynomial and sigmoid functions. The Boltzman function described the data accurately (R2=0.947–0.990). In addition, direct comparison of the six models with an F-test proved the superiority of the first. The best-fit parameters of the reference curve, i.e. the maximum and minimum values, the slope, and V50 (the SI at which SP duration is halfway between Min and Max) were 230.8±3.31 ms (x±SEM), –11.51±3.31 ms, 11.56±0.65%, and 49.82±0.65%, respectively. When the curves obtained with the circular coil were compared with those obtained with the figure-of-eight coil, there were differences between V50 (51.69±0.72 vs 47.95±0.82, P<0.001) and SP threshold (31.15 vs 24.77, P<0.01) whereas the other best-fit values did not differ significantly. Oxcarbazepine increased corticomotor threshold from 45.3±5.8% at baseline to 59.4±10.4% (P<0.001). According to the commonly used method, the drug significantly prolonged SP (from 117.6±42.4 ms to 143.5±46.5 ms, P<0.001) and, consequently, enhanced brain inhibition. In contrast, study of the SP curves led to the conclusion that oxcarbazepine does not affect the Max value and slope but significantly increases V50 and SP threshold (from 54.5±4.9% to 59.9±7.2% and from 29.1±6.4% to 34.6±6.8%, respectively, P<0.01). These findings imply that oxcarbazepine does not enhance brain inhibitory mechanisms. Thus, in situations characterized by significant changes in corticomotor threshold the proposed method provides results clearly different from a commonly used approach. It is concluded that S–R curves obtained with a figure-of-eight coil in 5% increments and fitted to a Boltzman function provide an accurate, comprehensive, and clinically applicable method for exploring SP.Presented in part at the meeting of the EFNS, Helsinki, September 2003 相似文献
55.
P. HAUGEN 《Acta physiologica (Oxford, England)》1982,114(2):179-186
The time course of the latency relaxation was studied at various temperatures in the range 0–26°C. Over the entire range the time of onset of the drop in tension, t1, was independent of sarcomere length. At temperatures above 12–15°C the falling phase had a point of inflexion, while at lower temperatures there was an interval during which the tension fell at a constante rate. The time when the rate of drop in tension had passed its maximum value t1,2, the time to the maximurn drop in tension t2, and the time when the tension crossed the resting level t3, all showed linear dependence on sarcomere length in the range from 2.1 to 2.7–3.4 μm. In this range the durations of the intervals t1.2-t1, t2-t1, and t3-t1 were nearly proportional to the distance from the Z-line to the end of the zone of overlap between the thick and the thin filaments. This could be explained as the activation being a longitudinal process starting from the Z-line. The slopes (dt/dS) of the linear portions of the time variables t1,2, t2, and t3 in a time-sarcomere length (S) diagram all had the same dependence on temperature giving a Q10 of 1.75. Under the assumption that the activation process followed a diffusion of calcium from the Z-line region to the zone of overlap a diffusion coefficient was estimated. At room temperature it had a magnitude of about 1/20 of that for calcium chloride in water. It had a dependence on temperature corresponding to an Arrhenius activation energy of about 37 kJ/mol which is about twice the activation energy for a simple diffusion of calcium in water. The results can be interpreted in terms of the time course of the latency relaxation mainly reflecting a longitudinal diffusion of calcium ions in the sarcoplasm. 相似文献
56.
The organization of the neonatal rat's brainstem trigeminal complex and its role in the formation of central trigeminal patterns 总被引:4,自引:0,他引:4
The present study delimits the relationship of primary trigeminal afferents to their targets, the brainstem trigeminal nuclei of the neonatal rat. Previously, the brainstem trigeminal complex of the rat has been subdivided on the basis of either cytoarchitectonics or patterns of succinic dehydrogenase activity into the principal sensory nucleus and the three subnuclei of the spinal trigeminal nucleus, oralis, interpolaris, and caudalis. In this paper, we demonstrate that each of these subdivisions can also be identified by its pattern of primary trigeminal afferents. In addition, we demonstrate that the terminations of these afferents are distributed in a punctate fashion which correlates with vibrissae-related patterns of histochemical staining. Further, vibrissae removal in the neonatal rat at any age studied results in a corresponding deafferentation of both the principal sensory nucleus and all subnuclei of the spinal trigeminal nucleus. This same procedure has a graded, age-dependent effect on the vibrissae-related pattern of cytochrome oxidase staining in somatosensory cortex. On this basis, we conclude that vibrissae-related pattern formation in the central trigeminal system can be best understood in terms of a single "sensitive" period for the entire system. We hypothesize that this is the period during which an interaction normally occurs between primary trigeminal afferents and target neurons of the principal sensory nucleus. 相似文献
57.
J Halldin 《Acta psychiatrica Scandinavica》1984,69(6):503-518
The principal reason for this epidemiological study was the lack of psychiatric morbidity studies in a predominantly urban population, by psychiatrists in direct interviews. The psychiatric examination, covering 1970-71, included a representative selection of 2,283 persons, 18-65 years old from "former" Stockholm County, and the 12-month prevalence of mental disorders was measured. The total of non-participants was 12%. Forty-seven percent had a psychiatric diagnosis - significantly more women (54%) than men (40%). Excluding the psychosomatic diagnoses, 31% of the population received a psychiatric diagnosis, which agrees closely with other contemporary studies of mental disorder in the Nordic countries. The primary diagnoses were: neuroses 26%, psychosomatic diagnoses 16%, schizophrenic/paranoid conditions or other psychoses 0.6%, affective disorders 0.2%, psychoorganic syndromes 1.2%, psychopathy 0.2%, character neurosis 1%, drug dependence 0.2% (as a primary or a secondary diagnosis 0.6%), alcoholism 1.4% (as a primary or a secondary diagnosis 3.1%) and mental retardation 0.4% (as a primary or a secondary diagnosis 0.8%). 相似文献
58.
目的分析ELISA和NAT平行的血液筛查模式对降低经输血感染病原体风险的有效性。方法收集常州市2016—2019年270215例无偿献血者血液标本,采用两次ELISA并行检测HBsAg、抗HCV、抗HIV和抗TP。268264例ELISA双阴性标本采用6人份混样(pool)NAT进行HBV DNA、HCV RNA和HIV RNA的检测,核酸阳性的pool进行拆分单检。结果270215例无偿献血者HBsAg、抗HCV、抗HIV和抗TP的阳性率分别为2.58‰(697例)、1.49‰(402例)、0.23‰(61例)和3.06‰(827例)。268264例酶免阴性无偿献血者HBV DNA、HCV RNA和HIV RNA阳性率分别为0.86‰(230例)、0.01‰(3例)和0.01‰(2例)。结论ELISA与NAT两种检测方法能相互补充,极大降低了输血感染病原体的残余风险,保障输血安全。NAT能进一步缩短血液传染性病毒的检测“窗口期”,检出隐匿性病毒。 相似文献
59.
目的 探讨婴儿期快速生长对青春期性发育的影响,对预防未来青春期提早发育提供依据。方法 选择2004年1月-2005年1月在温州市儿童医院及本院体检的198例生长过快的婴儿为观察组,另选择175名正常婴儿为对照组。根据出现月经初潮/遗精的时间点,把观察组分成性早熟组和正常发育组。采用Spearman相关性分析观察组婴儿1周岁的身高Δ值、体重Δ值与青春期性早熟的相关性。结果 观察组婴儿1周岁的身高Δ值、体重Δ值均显著大于对照组,差异有统计学意义(t=2.085,2.146,P<0.05);观察组儿童的身高、体重、体脂、骨龄值均显著大于对照组儿童,观察组儿童的T、E2、FSH、LH水平均显著高于对照组儿童,差异均有统计学意义(P<0.05)。对照组无性早熟患儿。观察组、早熟组和正常组的男女比例对比,差异无统计学意义(P>0.05)。早熟组身高、体重、体脂、骨龄值均显著大于正常组,早熟组T、E2、FSH、LH水平均显著高于正常组,差异有统计学意义(P<0.05)。观察组婴儿1周岁的身高Δ值、体重Δ值与青春期性早熟呈正相关(r=0.816,0.872,P<0.001)。结论 婴儿期快速生长可造成儿童青春期前肥胖和体脂过度,使青春期早发。控制婴儿期过快生长对预防未来青春期提早发育有重要意义。 相似文献
60.
目的探讨妊娠期糖尿病(GDM)患者产后糖代谢异常(AGM)转归及其影响因素。方法选择2019年1月至12月,于四川大学华西第二医院孕期被诊断为GDM,并于产后4~12周进行75 g口服葡萄糖耐量试验(OGTT)筛查的1175例单胎妊娠产妇为研究对象。根据其产后糖代谢是否正常,将其分为研究组(n=361,产后AGM者)与对照组(n=814,产后糖代谢正常者)。采用回顾性分析方法,收集受试者一般临床资料及孕期与产后4~12周75 g OGTT结果等,并采用成组t检验或χ^(2)检验进行统计学分析。对GDM患者产后AGM转归相关影响因素进行单因素分析与多因素非条件logistic回归分析,探讨其AGM转归的独立影响因素。本研究遵循的程序符合病例收集医院伦理委员会制定的伦理学标准,得到该伦理委员会批准[审批文号:医学科研2021伦审批第(181)号]。结果①24~28孕周时,1175例GDM患者75 g OGTT结果提示,空腹血糖(FPG)及OGTT 1、2 h血糖指标中,1、2、3项升高者分别为639例(54.4%)、373例(31.7%)与163例(13.9%)。②产后4~12周时,1175例GDM患者75 g OGTT结果提示,产后糖代谢正常者为814例(69.3%),AGM为361例(30.7%),包括空腹血糖受损(IFG)为19例(1.6%),糖耐量受损(IGT)为294例(25.0%),IFG+IGT为23例(2.0%),疑似2型糖尿病(T2DM)患者为25例(2.1%)。③产后AGM转归影响因素的单因素分析结果显示,研究组GDM患者年龄、糖尿病家族史发生率,24~28孕周OGTT 1、2 h血糖值,以及2项血糖指标(OGTT 1、2 h血糖)均升高与3项血糖指标(FPG及OGTT1、2 h血糖)均升高者所占比例,均显著高于对照组,而研究组仅1项血糖指标(FPG或OGTT 1 h血糖)升高者所占比例,则显著低于对照组,2组比较,差异均有统计学意义(P<0.05)。④多因素非条件logistic回归分析结果:模型1将受试者年龄、糖尿病家族史及24~28孕周OGTT 1、2 h血糖值进行多因素logistic回归分析结果显示,糖尿病家族史及24~28孕周OGTT 1、2 h血糖值,均为GDM患者产后AGM转归的独立危险因素(OR=1.693、1.205、1.355,95%CI:1.208~2.373、1.088~1.335、1.204~1.524,P=0.002、<0.001、<0.001)。模型2将受试者年龄、糖尿病家族史、24~28孕周OGTT血糖指标升高项目进行多因素logistic回归分析结果显示,糖尿病家族史及24~28孕周OGTT 2项血糖指标(OGTT 1、2 h血糖)升高与3项血糖指标均升高,均为GDM患者产后AGM转归独立危险因素(OR=1.668、1.421、1.747,95%CI:1.192~2.333、1.035~1.952、1.195~2.553,P=0.003、0.030、0.004);24~28孕周仅FPG或OGTT 1 h血糖升高为其独立保护因素(OR=0.401、0.646,95%CI:0.240~0.670、0.418~0.997,P<0.001、=0.048)。结论对于GDM患者产后AGM转归,临床应关注其年龄、糖尿病家族史、孕期OGTT结果等指标。对GDM高危人群进行上述指标持续监测与规范干预,是健全GDM孕前-孕期-产后全程管理的重要环节。 相似文献