全文获取类型
收费全文 | 16661篇 |
免费 | 1712篇 |
国内免费 | 23篇 |
专业分类
耳鼻咽喉 | 144篇 |
儿科学 | 545篇 |
妇产科学 | 532篇 |
基础医学 | 2413篇 |
口腔科学 | 272篇 |
临床医学 | 1959篇 |
内科学 | 3228篇 |
皮肤病学 | 192篇 |
神经病学 | 1303篇 |
特种医学 | 589篇 |
外国民族医学 | 3篇 |
外科学 | 2067篇 |
综合类 | 403篇 |
一般理论 | 11篇 |
预防医学 | 1904篇 |
眼科学 | 368篇 |
药学 | 1305篇 |
中国医学 | 12篇 |
肿瘤学 | 1146篇 |
出版年
2021年 | 208篇 |
2020年 | 146篇 |
2019年 | 238篇 |
2018年 | 260篇 |
2017年 | 210篇 |
2016年 | 230篇 |
2015年 | 242篇 |
2014年 | 343篇 |
2013年 | 529篇 |
2012年 | 692篇 |
2011年 | 781篇 |
2010年 | 479篇 |
2009年 | 405篇 |
2008年 | 663篇 |
2007年 | 703篇 |
2006年 | 652篇 |
2005年 | 674篇 |
2004年 | 688篇 |
2003年 | 665篇 |
2002年 | 574篇 |
2001年 | 538篇 |
2000年 | 551篇 |
1999年 | 455篇 |
1998年 | 219篇 |
1997年 | 184篇 |
1996年 | 168篇 |
1995年 | 194篇 |
1994年 | 158篇 |
1993年 | 149篇 |
1992年 | 408篇 |
1991年 | 403篇 |
1990年 | 412篇 |
1989年 | 360篇 |
1988年 | 382篇 |
1987年 | 366篇 |
1986年 | 326篇 |
1985年 | 293篇 |
1984年 | 262篇 |
1983年 | 221篇 |
1982年 | 126篇 |
1979年 | 217篇 |
1978年 | 175篇 |
1977年 | 145篇 |
1976年 | 150篇 |
1975年 | 151篇 |
1974年 | 153篇 |
1973年 | 175篇 |
1972年 | 142篇 |
1971年 | 129篇 |
1970年 | 137篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
992.
993.
On the Theory of Ion Transport Across the Nerve Membrane, III. Potassium Ion Kinetics and Cooperativity (with x = 4, 6, 9) 总被引:1,自引:0,他引:1
下载免费PDF全文
![点击此处可从《Proceedings of the National Academy of Sciences of the United States of America》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Terrell L. Hill Yi-Der Chen 《Proceedings of the National Academy of Sciences of the United States of America》1971,68(10):2488-2492
The calculations of Part II of this series have been extended to square (x = 4) and octahedral (x = 6) arrangements of subunits in a potassium channel (or gate). The conclusion is the same as before: experimental induction and superposition properties of gK(t), on depolarization, seem to rule out any significant degree of interaction or cooperativity between the (protein?) subunits of K+ channel. Calculations for x = 4, 6, and 9 have also been made for a square lattice of interacting channels (periodic boundary conditions). Because of apparent rapid convergence with x, it seems fairly safe to conclude that this model is unsatisfactory. There is some difficulty with superposition but the principal shortcoming is a failure to produce induction behavior. Aggregation models for the K+ channel are also discussed briefly here. They, too, appear rather unpromising (for the same reasons as seem to exclude conformational cooperativity within a channel). 相似文献
994.
995.
D W Hill 《International anesthesiology clinics》1969,7(4):1035-1036
996.
997.
Chemiluminescence by polymorphonuclear leukocytes from patients with active bacterial infection 总被引:10,自引:0,他引:10
Polymorphonuclear leukocytes of 18 patients during 19 episodes of active bacterial infection produced increased chemiluminescence (mean +/- standard error [SE], 56.3 +/- 4.4 X 10(3) cpm) when the production was compared to that of 29 uninfected controls (35.3 +/- 2.4 X 10(3) cpm; P less than 0.01). Chemiluminescence production remained increased with persistent infection but fell to the levels of controls with appropriate therapy. Phagocytic uptake as determined with radiolabeled bacteria was increased, and chemotactic responsiveness was markedly enhanced in the patients (mean index +/- SE, 260 +/- 51) when these responses were compared with those of controls (77 +/- 18). Chemiluminescence and chemotactic activity correlated in the patients with bacterial infection (r = 0.76), but one function did not appear to depend upon the intactness of the other. The ratio of cyclic guanosine 3',5'-phosphate to cyclic adenosine 3',5'-hosphate in the polymorphonuclear leukocytes of patients with infections (mean +/- SE, 0.102 +/- 0.0008) was also significantly higher than in controls (0.067 +/- 0.007). These data indicate that the polymorphonuclear leukocytes of the majority of patients with active bacterial infection are in an activated state both functionally and metabolically. 相似文献
998.
Reliable diagnostic methods for head and neck vascular lesions are needed. The technique of dynamic computed tomography (CT) is used to delineate two aberrant subclavian arteries, one carotid artery aneurysm, and one angiofibroma. Five or six 4.8-s CT scans were obtained sequentially, separated by a 1.2-s interscan interval. Computer-generated iodinated contrast concentration (CT number) v time curves showed rapid influx of contrast, high peak density, and rapid uninterrupted contrast runoff. Simultaneous bone and soft-tissue visualization at the time of peak contrast enhancement provides excellent delineation of the malformations and angiofibroma. The technique is noninvasive, and it eliminates the potential complications of arteriography and biopsy. We conclude that dynamic CT is an excellent method for diagnosis of head and neck vascular lesions. 相似文献
999.
S C Hill D A Christensen C H Durney 《International journal of radiation oncology, biology, physics》1983,9(6):893-904
The electric fields and power deposition patterns generated in two-dimensional inhomogenous models exposed to the axially directed uniform magnetic fields of an infinitely long solenoid are calculated numerically. The fields are calculated using the method of moments (Galerkin procedure) with linear basis and weighting functions. This low-frequency analysis is useful for studying the power deposition patterns attributable to solenoidal inductive applicators operated at frequencies up to 13.56 MHz. For the models we have studied, the ratio of power per volume deposited into the tumor to power per volume deposited into the immediately surrounding tissue is largest for tumors in the lung, although the power per volume deposited into the outermost layer is still much larger than the power per volume deposited into the tumor; it may be possible, however, to cool this region adequately from the body surface. When the complex permittivity of the tumor model is similar to that of the region in which it is embedded, the currents in the torso and tumor circulate primarily around the center of the body, as has been previously calculated for concentric cylinders. When the complex permittivity of the tumor is much greater than the region in which it is embedded, the currents in the tumor circulate primarily around the center of the tumor. 相似文献
1000.
R P Hill 《International journal of radiation oncology, biology, physics》1983,9(7):1043-1047
Groups of LAF1 mice were given thoracic irradiation using 60Co gamma-rays at dose-rates of 0.05 Gy/min (LDR) or 1.1 Gy/min (HDR) and the death of the animals was monitored as a function of time. It was found that the time pattern of animal deaths was similar for the two different dose-rates. Dose response curves for animals dying at various times up to 500 days after irradiation were calculated and the LD50 values determined. The curves for the LD50 values, plotted as a function of the time at analysis for treatment at HDR or LDR, were essentially parallel to each other but separated by a factor (LDR/HDR) of about 1.8. This indicates that the sparing effect of LDR treatment is the same for deaths occurring during the early pneumonitis phase or during the late fibrotic phase of lung damage. The available information on the response of patients to whole thoracic irradiation, given for either palliation or prior to bone marrow transplantation, suggests that for similar dose-rates to those studied here the ratio (LDR/HDR) is only 1.2-1.3. This difference between the animal and human data may reflect the modifying effect of the large doses of cytotoxic drugs used in combination with the irradiation of bone marrow transplant patients. 相似文献