全文获取类型
收费全文 | 23144篇 |
免费 | 1840篇 |
国内免费 | 871篇 |
专业分类
耳鼻咽喉 | 91篇 |
儿科学 | 232篇 |
妇产科学 | 314篇 |
基础医学 | 1882篇 |
口腔科学 | 289篇 |
临床医学 | 1394篇 |
内科学 | 2345篇 |
皮肤病学 | 213篇 |
神经病学 | 873篇 |
特种医学 | 1324篇 |
外国民族医学 | 4篇 |
外科学 | 652篇 |
综合类 | 3703篇 |
预防医学 | 1522篇 |
眼科学 | 391篇 |
药学 | 6835篇 |
14篇 | |
中国医学 | 2289篇 |
肿瘤学 | 1488篇 |
出版年
2024年 | 63篇 |
2023年 | 335篇 |
2022年 | 838篇 |
2021年 | 1003篇 |
2020年 | 766篇 |
2019年 | 657篇 |
2018年 | 598篇 |
2017年 | 695篇 |
2016年 | 752篇 |
2015年 | 828篇 |
2014年 | 1289篇 |
2013年 | 1384篇 |
2012年 | 1457篇 |
2011年 | 1487篇 |
2010年 | 1272篇 |
2009年 | 972篇 |
2008年 | 1125篇 |
2007年 | 1213篇 |
2006年 | 1037篇 |
2005年 | 948篇 |
2004年 | 823篇 |
2003年 | 740篇 |
2002年 | 615篇 |
2001年 | 544篇 |
2000年 | 504篇 |
1999年 | 374篇 |
1998年 | 314篇 |
1997年 | 308篇 |
1996年 | 243篇 |
1995年 | 223篇 |
1994年 | 234篇 |
1993年 | 166篇 |
1992年 | 197篇 |
1991年 | 247篇 |
1990年 | 224篇 |
1989年 | 148篇 |
1988年 | 163篇 |
1987年 | 129篇 |
1986年 | 112篇 |
1985年 | 170篇 |
1984年 | 168篇 |
1983年 | 141篇 |
1982年 | 96篇 |
1981年 | 68篇 |
1980年 | 59篇 |
1979年 | 47篇 |
1978年 | 30篇 |
1977年 | 16篇 |
1976年 | 10篇 |
1972年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
951.
The mutagenic activity of solvent extracts of specific manufacturing lots of saccharin produced by the Sherwin-Williams process was studied in detail. All the individual components identified were found to be non-mutagenic. The mutagenic activity of saccharin lot S-1469 was traced to a moderately polar chromatographic fraction representing impurities present in the saccharin at a level of less than 1.5 ppm, but was not attributable to a single component. In view of the low level of mutagenic activity observed and the low concentration of total impurities in Sherwin-Williams saccharin, the mutagenic material(s) are probably of no significance in animal feeding studies. 相似文献
952.
P J Watson 《European journal of pharmacology》1972,20(1):60-70
The moving fluid electrode technique was used on the isolated rat superior cervical ganglion to investigate changes of potential elicited by drugs independently of induced action potentials. The existence of 3 distinct phases was confirmed. These comprise, firstly, a strong depolarization which is predominantly nicotinic in origin: this is succeeded by a hyperpolarization which does not represent a compensatory recovery process although it, too, is essentially nicotinic. Further evidence is presented to support the concept that catecholamines may be involved at this stage. The last phase is a slow but significant depolarization, and this is wholly muscarinic in nature. 相似文献
953.
Zusammenfassung Cerebrale Ausfälle nach Kreislaufstillstand werden vereinzelt auch von eindrucksvollen spinalen Läsionen begleitet. In 4 Fällen nach temporär überlebtem Kreislaufstillstand fanden sich komplette und inkomplette Nekrosen in der grauen Substanz, bevorzugt im Lumbalmark. Die Nekrosen manifestieren sich zuerst im Zentrum der Grisea (zentrales Vorderhorn, Zona intermedia, Basis des Hinterhorns) und dehnen sich je nach Schwere auf das Vorder- und Hinterhorn aus. Die in einem Fall besonders schweren Mikrozirkulationsstörungen lassen auf die wesentliche Mitwirkung intramedullärer Kreislaufstörungen in der postischämischen Schockphase bei der Genese der Myelomalacie schließen. Demgegenüber wird die Bedeutung extramedullärer Gefäßalterationen meist überschätzt. Diese spinalen Läsionen entsprechen in der formalen Genese den bekannten cerebralen anoxischvasalen Ausfällen nach Kreislaufstillstand.
Spinal-cord lesions following temporary circulatory arrest
Summary Incidental severe damage of the spinal cord may accompany the cerebral lesions after temporary circulatory arrest. In 4 cases of transient survival after circulatory arrest extensive necroses developed in the spinal gray matter, particularly in the lumbar region. The lesions are localized chiefly in the central gray matter (zona intermedia) extending to the anterior and posterior horns. The intramedullary microcirculatory disturbances developing in the postischemic phase play a significant part in the pathogenesis of myelomalacia, whereas alterations fail to appear in the external vessels. These spinal lesions correspond formally to the anoxic damage of the cerebral structures after circulatory arrest.
Herrn Professor Dr. Wilhelm Maßhoff zum 65. Geburtstag. 相似文献
954.
The ultrasonic properties (velocity at 2·81 and 5·04 MHz, absorption in the range 1–15 MHz and vibration potential at 200 kHz) of amniotic liquid have been investigated. The results indicate that at physiological pH the absorption is essentially due to the proteins found in amniotic liquid, its vibration potential to the sodium chloride contained in this fluid while the velocity appears to be determined both by the proteins and sodium chloride. In the acid range (pH ~ 3) and alkaline range (pH ~ 9·6), proton transfer processes involving a low molecular weight component of amniotic liquid, in addition to those involving the proteins, contribute to the absorption of ultrasound by amniotic liquid. 相似文献
955.
《Nutrition reviews》1979,37(8):250-252
Endocrine adaptation to starvation and low protein hypocaloric diets is discussed as a basis for understanding the clinical expression of PCM. Infections common in PCM increase acute phase reactants, which may contribute to the derangement of homeostasis in PCM. 相似文献
956.
A novel numerical deconvolution method is presented that enables the estimation of drug absorption rates under time-variant disposition conditions. The method involves two components. (1) A disposition decomposition-recomposition (DDR) enabling exact changes in the unit impulse response (UIR) to be constructed based on centrally based clearance changes iteratively determined. (2) A non-parametric, end-constrained cubic spline (ECS) input response function estimated by cross-validation. The proposed DDR-ECS method compensates for disposition changes between the test and the reference administrations by using a "beta" clearance correction based on DDR analysis. The representation of the input response by the ECS method takes into consideration the complex absorption process and also ensures physiologically realistic approximations of the response. The stability of the new method to noisy data was evaluated by comprehensive simulations that considered different UIRs, various input functions, clearance changes and a novel scaling of the input function that includes the "flip-flop" absorption phenomena. The simulated input response was also analysed by two other methods and all three methods were compared for their relative performances. The DDR-ECS method provides better estimation of the input profile under significant clearance changes but tends to overestimate the input when there were only small changes in the clearance. 相似文献
957.
958.
目的检测应用重组人腺病毒-p53(SBN-1)基因抗癌注射液的临床试验病例的机体免疫反应和组织样本p53基因变异状况,以客观评价临床疗效.方法通过对22例SBN-1治疗前后患者肿瘤组织样本的p53基因进行分析,明确用于重组腺病毒p53基因联合放疗二期临床试验的肿瘤标本中p53基因的变异状况并检测癌症患者血清中抗SBN-1抗体水平;用免疫组织化学技术检测p53基因的表达水平;显微切割技术分离微量肿瘤组织制备DNA进行聚合酶链反应扩增;变性高效液相色谱技术(DHPLC)和DNA测序技术检测内源性p53基因突变的分布和类型.采用酶联免疫吸附实验检测血清中抗腺病毒抗体水平、血清中腺病毒IgG和IgM抗体水平.结果有p53突变的病例中完全缓解率较高,通过免疫组织化学检测阳性率为40%(6/15),DHPLC和DNA测序检测点突变为32%(7/22).实验结果也表明试验者绝大多数近期未感染过腺病毒,IgM阳性率低于6%(1/16),接受SBN-1治疗的患者随注射SBN-1次数增加,血清中抗SBN-1特异性抗体水平升高.结论通过对入组病例临床样本p53基因变异和SBN-1抗体水平的检测,为客观评价临床疗效提供了基因和蛋白水平的指标. 相似文献
959.
Menstrual cycle affects bladder pain sensation in subjects with interstitial cystitis 总被引:1,自引:0,他引:1
Powell-Boone T Ness TJ Cannon R Lloyd LK Weigent DA Fillingim RB 《The Journal of urology》2005,174(5):1832-1836
PURPOSE: Using psychophysical methods we compared the effect of the menstrual cycle on bladder sensation in subjects with the diagnosis of interstitial cystitis (IC) and in controls. MATERIALS AND METHODS: Female participants with normal menstrual cycles, including 7 with IC and 8 healthy controls, were recruited into this study. They completed daily diaries related to bladder pain and other body pain, and tracked daily micturition frequency. In a subset formal psychophysical testing of thermal and ischemic pain was performed at 2 times of the menstrual cycle, corresponding to the luteal and follicular phases. Cystometrograms were performed at the same time. RESULTS: Subjects with IC had higher pain scores and frequency than controls throughout the entire menstrual cycle. Pain scores were highest in the perimenstrual period in subjects with IC and controls. Micturition frequency was highest in the perimenstrual period in subjects with IC. Cystometric evaluation of a first need to void and the evocation of bladder pain demonstrated that lower intravesical volume and pressure were necessary to evoke bladder pain during the follicular period than during the luteal period in subjects with IC, although there was no effect on the first need to void. CONCLUSIONS: These findings are consistent with clinical lore that suggests a perimenstrual flare in pain in subjects with IC. To our knowledge it also demonstrates for the first time a menstrual cycle effect on bladder sensory function in subjects with IC. This suggests a potential role of gonadal hormones on bladder sensory processing and, therefore, a potential role for hormonal modulation as a therapeutic modality in this patient population. 相似文献
960.
Gillespie JI 《BJU international》2005,96(Z1):22-28
Although caution should be used when applying animal data to human physiology, if care is taken to differentiate between general principles and complications of detail, particular to the species being examined, then experimentation on animal models can reveal basic phenomena in the bladder that offer clues to the origin of urgency. Recent data from the whole isolated bladder of guinea pigs showed unexpected complexities in autonomous activity during the filling phase of the micturition cycle: small, transient increases in intravesical pressure were associated with propagating waves of contractile activity and localized stretches of bladder wall. This complex, coordinated activity suggests that there are mechanisms within the bladder wall devoted specifically to generating phasic activity. Thus, there appear to be two systems controlling detrusor contractions: one associated with overall contractions similar to the micturition contraction and the other generating phasic activity. The mechanisms generating the phasic activity appear to be the point of complex integration of both excitatory and inhibitory inputs. There is evidence that local activity in the bladder wall generates afferent discharge, which probably contributes to bladder sensations. Animal data suggest a novel motor/sensory system incorporating contractile (motor) events, which cause stretches resulting in activation of afferent nerves (sensory). The motor element of this system appears to be controlled in a highly complex fashion such that the amplitude and frequency of the motor activity can be modulated by a variety of inputs. This raises the possibility that the sensitivity of the system informing the central nervous system, and thus awareness of the bladder's state during the micturition cycle, can be manipulated, possibly via novel drugs targeted at areas involved in overactive bladder, including urgency incontinence. 相似文献