全文获取类型
收费全文 | 2543篇 |
免费 | 108篇 |
国内免费 | 56篇 |
专业分类
耳鼻咽喉 | 14篇 |
儿科学 | 7篇 |
妇产科学 | 4篇 |
基础医学 | 751篇 |
口腔科学 | 18篇 |
临床医学 | 58篇 |
内科学 | 204篇 |
皮肤病学 | 2篇 |
神经病学 | 855篇 |
特种医学 | 84篇 |
外科学 | 45篇 |
综合类 | 147篇 |
预防医学 | 42篇 |
眼科学 | 18篇 |
药学 | 372篇 |
中国医学 | 47篇 |
肿瘤学 | 39篇 |
出版年
2023年 | 10篇 |
2022年 | 22篇 |
2021年 | 30篇 |
2020年 | 27篇 |
2019年 | 35篇 |
2018年 | 22篇 |
2017年 | 46篇 |
2016年 | 49篇 |
2015年 | 41篇 |
2014年 | 80篇 |
2013年 | 104篇 |
2012年 | 90篇 |
2011年 | 138篇 |
2010年 | 115篇 |
2009年 | 129篇 |
2008年 | 141篇 |
2007年 | 119篇 |
2006年 | 132篇 |
2005年 | 84篇 |
2004年 | 92篇 |
2003年 | 51篇 |
2002年 | 61篇 |
2001年 | 36篇 |
2000年 | 49篇 |
1999年 | 43篇 |
1998年 | 66篇 |
1997年 | 60篇 |
1996年 | 48篇 |
1995年 | 53篇 |
1994年 | 47篇 |
1993年 | 42篇 |
1992年 | 40篇 |
1991年 | 38篇 |
1990年 | 35篇 |
1989年 | 33篇 |
1988年 | 38篇 |
1987年 | 38篇 |
1986年 | 29篇 |
1985年 | 67篇 |
1984年 | 46篇 |
1983年 | 43篇 |
1982年 | 46篇 |
1981年 | 44篇 |
1980年 | 41篇 |
1979年 | 34篇 |
1978年 | 23篇 |
1977年 | 16篇 |
1976年 | 8篇 |
1974年 | 6篇 |
1971年 | 5篇 |
排序方式: 共有2707条查询结果,搜索用时 15 毫秒
51.
Paul McIntosh Andrew P. Southan Sobia Akhtar Christina Sidera Yuri Ushkaryov J. Oliver Dolly B. Robertson 《Pflügers Archiv : European journal of physiology》1997,435(1):43-54
We have examined the effects of co-expression of Kvβ1.1 and Kvβ2.1 subunits on the gating of rat brain Kv1.4 channels, expressed
in Xenopus oocytes. Expression of Kv1.4 subunits alone produced a rapidly inactivating ”A” type current, which activated at potentials
beyond –60 mV in a solution containing high levels of rubidium. Current activation curves obtained from tail current measurements
were fitted with a Boltzmann function, with V
1/2 = –47 mV and k = 10 mV. Neither the Kvβ1.1 nor Kvβ2.1 subunits altered the voltage dependence of activation. Both subunits accelerated the
activation time constant of Kv1.4, without affecting its voltage dependence. Surprisingly, the Kvβ2.1 subunit, which lacks
an N-terminal inactivation domain, was almost as effective as the Kvβ1.1 subunit in speeding up Kv1.4. Steady-state inactivation
of Kv1.4 was unchanged upon co-expression with either Kvβ1.1 or Kvβ2.1 subunits. Kv1.4 recovered from inactivation with two
time constants; apart from an ≈ 50% lengthening of the slow time constant with a high Kvβ2.1 injection ratio, neither time
constant was altered by either the Kvβ1.1 or Kvβ2.1 subunits, suggesting little interaction with recovery from C-type inactivation.
Clearly, β subunits have the potential to modify the gating of Kv1.4 channels in the brain more subtly than has been suggested
previously.
Received: 17 March 1997 / Accepted: 30 June 1997 相似文献
52.
Vasoactive intestinal polypeptide nerve processes and cell bodies were identified by electron microscopic immunocytochemistry in the rat small intestine. Labeled nerve processes were numerous in the inner circular smooth muscle coat and mainly in the mucosa, but were absent in the longitudinal muscle layer. Submucosal blood vessels were often surrounded by immunoreactive vasoactive intestinal polypeptide positive nerves, in close associations (distance less than 40 mn) to blood vessel basement membranes and to smooth muscle cells. In the ganglia of the myenteric and submucous plexuses, labeled fibers surrounded unstained neural cell bodies. The synaptic vesicles of vasoactive intestinal polypeptide positive terminals were 35-40 nm in diameter and some dense core vesicles (80-120 nm in diameter) were also observed in the same profiles. These observations suggest that vasoactive intestinal polypeptide nerves may participate in regulating smooth muscle activity and local blood flow in the small intestine. 相似文献
53.
Changes in membrane potential and potassium concentration in the extracellular space ([K+]e) of rabbit vagus nerve were measured simultaneously during electrical activity and during the period of recovery using a
modified sucrose-gap method and potassium-sensitive microelectrodes. After stimulation for 15 s at 15 Hz the main activity-induced
increase in [K+]e reached 16.9 mM. This increase in [K+]e was paralleled by a depolarization of the preparation. The period of activity was followed by a post-tetanic hyperpolarization
(PTH) lasting tens of seconds, generated by the axonal electrogenic Na+-K+ pump and to a lesser extent by the pump of the surrounding Schwann cells. The amplitude of the PTH dramatically increased
in experiments in which inward currents were blocked by removal of Cl– or after application of Cs+ or Ba2+, indicating that under normal conditions the current generated by the Na+-K+ pump is strongly short-circuited. A pharmacological and kinetic study showed that these currents are: (1) the hyperpolarization-activated
current I
h, and (2) the inwardly rectifying I
KIR current. The results show that the latter originates from Schwann cells. Our data indicate that in non-myelinated nerves
there is a subtle association of inward ionic channels which (1) helps the cell to maintain an optimal membrane potential
after a period of activity, and (2) contributes to the removal of excess K+ from the extracellular space.
Received: 7 August 1997 / Received after revision 6 April 1998 / Accepted: 15 April 1998 相似文献
54.
A. I. Vislobokov V. I. Prosheva A. Ya. Polle 《Bulletin of experimental biology and medicine》2004,138(10):390-392
The membranotropic effects of TVF tanacetan pectin polysaccharide derived from Tanacetum vulgare L. was studied by the voltage-clamp method on isolated neurons of Lymnaea stagnalis mollusk. TVF in concentrations of 0.1-10.0 µg/ml nonselectively activated the outward potassium and total inward (sodium and calcium) ionic currents (slightly dose-dependently and reversibly increased their amplitude by 5–10%) and decreased nonspecific leakage current.Translated from Byulleten Eksperimentalnoi Biologii i Meditsiny, Vol. 138, No. 10, pp. 439–441, October, 2004 相似文献
55.
On the search for the sources of the electroencephalogram 总被引:1,自引:0,他引:1
56.
K. B. Walsh S. H. Bryant A. Schwartz 《Pflügers Archiv : European journal of physiology》1987,409(1-2):217-219
The calcium channel-inhibiting drugs nitrendipine and diltiazem represent two important classes of organic calcium antagonists. In the present study, the effect of these drugs on calcium currents and charge displacement currents in bullfrog semitendinosus muscle fibers was examined using a vaseline gap voltage clamp. Nitrendipine (10 M) reduced the quantity of charge that moved both during the ON phase (QON) and the OFF phase (QOFF) of charge movement. This action appeared to be most selective for QON. However, at this same concentration, nitrendipine had no blocking action on inward calcium currents. In contrast to these findings, diltiazem blocked calcium currents in a concentration-dependent manner, while slightly increasing the quantity of charge moved during QON and QOFF. The enhancement of charge movement by diltiazem resulted from two actions. First, diltiazem shifted the voltage-dependence of charge movement to more negative potentials. Second, diltiazem increased the maximum amount of charge moved. (Supported by NIH NS 03178 and HL 07382.) 相似文献
57.
Types of nerves in the enteric nervous system 总被引:11,自引:0,他引:11
The enteric nervous system is one of the three divisions of the autonomic nervous system, the others being the sympathetic and parasympathetic. In contrast to the other divisions, it can perform many functions independently of the central nervous system. It consists of ganglionated plexuses, their connections with each other, and nerve fibres which arise from the plexuses and supply the muscle, blood vessels and mucosa of the gastrointestinal tract. The enteric nervous system contains a large number of neurons, approximately 107 to 108. About ten or more distinct types of enteric neurons have been distinguished on electrical, pharmacological, histochemical, biochemical and ultrastructural grounds as well as on the basis of their modes of action. Both excitatory and inhibitory nerves supply the muscle and there are inhibitory and excitatory interneurons within the enteric plexuses. There are also enteric nerves which supply intestinal glands and blood vessels, but these receive less emphasis in this commentary.Correlations between groups of neurons defined on different criteria are poor and in many cases the physiological roles of the nerves are not known. The functions of noradrenergic nerves which are of extrinsic origin are reasonably well understood, but cholinergic nerves in the intestine are the only intrinsic nerves for which both the transmitter and to some extent the functions are known. In the case of non-cholinergic, non-noradrenergic enteric inhibitory nerves, the functions are understood but the transmitter is yet to be determined, both adenosine 5′-triphosphate and vasoactive intestinal polypeptide having been proposed. Other nerves have been defined pharmacologically (non-cholinergic excitatory nerves to neurons and muscle, intrinsic inhibitory inputs to neurons, and enteric, non-cholinergic vasodilator nerves) and histochemically (intrinsic amine-handling neurons and separate neurons containing peptides: substance P, somatostatin, enkephalins, vasoactive intestinal polypeptide, gastrin cholecystokinin tetrapeptide, bombesin, neurotensin and probably other peptides). Little is known of the functions of these nerves, although a number of proposals which have been made are discussed. 相似文献
58.
J. L. Bossu J. L. Rodeau A. Feltz 《Pflügers Archiv : European journal of physiology》1989,414(1):89-91
The patch-clamp technique in whole-cell configuration was, used to investigate the kinetics of decay of calcium currents in rat sensory neurones. Whole-cell recording permitted control of the internal medium, particularly of the internal free calcium concentration, which was maintained at either 10–9 M or 10–6 M using a high concentration of Ca buffer. The inactivation decay of the total Ca current elicited above –10 mV was found to be faster at pCa 6 than at pCa 9. The total current contained three exponential components which were tentatively identified as the three types of Ca currents (ICaT, ICaN and ICaS). Kinetic analyses indicated that the control of the inactivation process by internal Ca results from an effect on both high-threshold Ca currents, ICaN, and ICaS. The inactivation kinetics reported in the literature presents a large variability depending on the cell type. We propose that this variability may result from differences in the capacity of those cells to control their internal Ca. 相似文献
59.
60.
Mollie E. Holman John P. Weinrich 《Pflügers Archiv : European journal of physiology》1975,360(2):109-119
Summary The membrane potential of smooth muscle cells in the circular layer of the guinea pig ileum was recorded using intracellular electrodes. Transmural stimulation, in the presence of atropine, caused a transient hyperpolarization, an inhibitory junction potential (IJP). IJP's are thought to result from the action of transmitter released from intramural inhibitory nerves. It has been reported that, in the guinea pig jejunum, the amplitude of the IJP resulting from field stimulation is not altered by changes in the calcium and magnesium ion concentration in the bathing solution. Experiments reported here have shown that the IJP amplitude decreased markedly on reducing the calcium ion concentration and or increasing the magnesium ion concentration. Indirect evidence is presented suggesting that the decrease in amplitude of the IJP is due to a decrease in the amount of transmitter released. 相似文献