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1.
目的:优选散结消肿贴中大黄、重楼的渗漉提取工艺。方法:以总固体物得率和总蒽醌得率为指标,用正交实验优选。结果:工艺中影响最大的因素是乙醇浓度,其次是乙醇用量,浸泡时间影响较小。最佳工艺条件为乙醇浓度65%,乙醇用量8倍量。浸泡时间24h。结论:渗漉法操作简单,成份破坏少,用优选所得条件进行提取,总蒽醌和总固体物得率均较高,优选结果可用于散结消肿贴中大黄、重楼的提取。 相似文献
2.
Using the whole-cell configuration of the patch clamp technique, calcium-activated potassium currents (IK,Ca) were investigated in ramified murine brain macrophages. In order to induce IK,Ca the intracellular concentration of nominal free Ca2+ was adjusted to 1μM. The Ca2+-activated K+ current of brain macrophages did not show any voltage dependence at test potentials between –120 and +30mV. A tenfold change
in extracellular K+ concentration shifted the reversal potential of IK,Ca by 51mV. The bee venom toxin apamin applied at concentrations of up to 1μM did not affect IK,Ca. Ca2+-activated K+ currents of ramified brain macrophages were highly sensitive to extracellularly applied charybdotoxin (CTX). The half-maximal
effective concentration of CTX was calculated to be 4.3nM. In contrast to CTX, the scorpion toxin kaliotoxin did not inhibit
IK,Ca at concentrations between 1 and 50nM. Tetraethylammonium (TEA) blocked 8.0% of IK,Ca at a concentration of 1mM, whereas 31.4% of current was blocked by 10mM TEA. Several inorganic polyvalent cations were tested
at a concentration of 2mM for their ability to block IK,Ca. La3+ reduced IK,Ca by 72.8%, whereas Cd2+ decreased IK,Ca by 17.4%; in contrast, Ni2+ did not have any effect on IK,Ca. Ba2+ applied at a concentration of 1mM reduced IK,Ca voltage-dependently at hyperpolarizing potentials.
Received: 17 January / Accepted: 5 May 1997 相似文献
3.
目的:观察福辛普利晚期预处理对缺氧复氧心室肌细胞Na /Ca2 交换电流的影响。方法:应用全细胞膜片钳方法,记录观察酶解的成年豚鼠心室肌细胞Na /Ca2 交换电流在缺氧复氧期的变化。结果:缺氧复氧明显增加心肌Na /Ca2 交换电流,在-100mV和 60mV时较对照组分别增加41.05%及32.75%,福辛普利预处理后可明显抑制缺氧复氧心肌Na /Ca2 交换电流,在-100mV和 60mV时分别减少17.90%及14.20%,有助于减少钙内流,减轻钙超载。结论:福辛普利预处理可抑制缺氧复氧心肌Na /Ca2 交换电流逆向转运。 相似文献
4.
5.
E. Schlatter U. Fröbe R. Greger 《Pflügers Archiv : European journal of physiology》1992,421(4):381-387
The study of ion conductances in the intact cortical collecting duct (CCD) with the patch-clamp method is rather difficult. An optimized method to isolate CCD cells from rat kidneys using an in vivo followed by an in vitro enzyme digestion is described. Individual CCD segments were collected after this digestion and incubated in EGTA-buffered medium. This procedure resulted in single cells or cell clusters. These freshly isolated CCD cells were studied with different modifications of the patch-clamp method. Membrane voltages measured in the cell-attached-nystatin configuration were –74 ±1mV (n=13) and –68±3 mV (n=22) in cells isolated from normal and mineralocorticoid-treated rats respectively. These values and those measured with the nystatin-perforated slow-whole-cell configuration (–79 ±1mV, n=23) are comparable to those measured in principal cells of isolated CCD segments. The cells hyperpolarized after the addition of amiloride and depolarized with the addition of adiuretin to the bath. The amiloride effect was enhanced when cells were isolated from deoxycorticosterone-acetate-treated rats. The cells were strongly depolarized upon elevation of the extracellular K+-concentration and did not demonstrate a measurable Cl– conductance. A large-conductance K+ channel (174 pS, n=5, cell-attached, 145 mmol/l K+ in the pipette; 140 pS, n=12, cell-free, 3.6 mmol/l K+ in the bath) was seen. It had a very low activity on the cell, but a high open probability when excised into a solution with 1 mmol/l Ca2+ on the cytosolic side. More often a small-conductance K+ channel (36–52 pS, n=19, cell-attached; 30 pS, n=5, cell-free) with a high open probability was found on the cell. These freshly isolated cells seem to be a powerful preparation to study the properties and regulation of ion conductances of rat CCD with several electrophysiological methods. These freshly isolated CCD cells maintain the conductance properties known from principal cells of the intact CCD. 相似文献
6.
Patch clamp techniques were used to study whole cell ionic currents in Schwann cells (SC) from a tropical marine fish, the bicolor damselfish, Pomacentrus partitus. The bicolor damselfish is affected by a disease termed damselfish neurofibromatosis (DNF), being developed as an animal model of neurofibromatosis-type 1 (NF1) in humans. NF1 affects SC, fibroblasts, and perineurial cells. The sole depolarization-activated ionic current present in cultured SC from normal fish peripheral nerve and from neurofibromas of fish with induced or spontaneously occurring DNF was an inactivating K+ current (K current), with a strong dependence on the Nernst potential for K+. This K current activated at depolarizations to -40 mV and above and inactivated during a maintained test pulse (0.2-1 s), but inactivation was significantly greater in tumored SC. Both currents were inhibited by 4-aminopyridine (Kd ? 1 mM) and by dendrotoxin (15 μM) but were insensitive to extracellular tetraethyammonium (≤ 150 mM), indicating that the whole cell currents were similar pharmacologically. The currents could be distinguished on the basis of their sensitivity to depolarized holding potential, with normal cells less sensitive. Half-inactivation of the current was -32 mV in normal cells and -38 mV in tumored cells. Inactivation curves constructed from the average normalized current for many SC were significantly different in normal and tumored cells. When the depolarized holding potential was maintained between test depolarizations, greater voltage-dependent inactivation in tumored cells was apparent. Normal cells maintained an average of 36% of peak current at a holding voltage of ?40 mV, while in tumored cells this average was 12%, a significant difference. © 1994 Wiley-Liss, Inc. 相似文献
7.
P. SCHWARZ H. A. SØRENSEN I. TRANSBØL Mineral Metabolic Research Group 《European journal of clinical investigation》1994,24(8):553-558
Abstract. The objective of the present study was to compare the calcium set-points of E. M. Brown and A. M. Parfitt obtained by sequential citrate and calcium clamp in patients with primary hyperparathyroidism and healthy controls. Twenty-six patients with primary hyperparathyroidism were investigated and compared to 22 healthy volunteers. All participants were investigated by sequential calcium lowering and raising comprising the following four phases: Phase (1) blood ionized calcium lowering of about 0·20 mmol l-1; phase (2) steady-state (relative) hypocalcaemia of blood ionized calcium 0·20 mmol l-1 below baseline; phase (3) blood ionized calcium is raised to about 0·20 mmol l-1 above baseline; and phase (4) (relative) hypercalcaemia of blood ionized calcium 0·20 mmol l-1 above baseline. Serum parathyroid hormone (1–84) was measured by an immunoradiometric assay. Blood ionized calcium was measured by a calcium selective electrode. We found the calcium set-points of Parfitt to be 1·42 mmol l-1 (SD 0·12, n= 52) vs. 1·25 mmol l-1 (SD 0·04, n= 44) in patients and controls, respectively (P < 0·001). The calcium set-points of Brown were 1·32 mmol l-1 (SD 0·10, n= 26) vs. 1·13 mmol l-1 (SD 0·04, n= 22), respectively (P < 0·001). By comparing the calcium set-points of Parfitt and Brown, a strikingly good correlation was observed, in patients (r= 0·91, P < 0·001) and in controls (r= 0·85, P < 0·001). We demonstrate in this paper in vivo that Brown's and Parfitt's calcium set-points are raised in primary hyperparathyroidism and return to normal following parathyroidectomy. The values for Brown's and Parfitt's calcium set-points are significantly different, but strikingly well correlated, supporting the view that Brown and Parfitt describe two different points on the same sigmoidal curve, corresponding to 50% and about 85% inhibition of PTH maximum, respectively. The mathematical form of the sigmoidal curve between blood ionized calcium and parathyroid hormone is very similar in primary hyperparathyroidism and normal humans. 相似文献
8.
壳聚糖对豚鼠单一心室肌细胞延迟外向钾电流的作用 总被引:3,自引:1,他引:2
研究壳聚糖对豚鼠单一心室肌细胞延迟外向钾电流(Ik)的作用,从离子通道角度初步春作用机理。应用膜片钳全细胞记录方式,设保持电位为-40mV,指令电位为-60 ̄+70mV,步阶脉冲10mV,刺激频率1Hz,波宽300ms,刺激间隔6s的方波钳制方案。结果表明壳聚糖能抑制Ik,并具有浓度依赖关系,能抑制豚鼠单一心室肌细胞延迟外向K^+电流。 相似文献
9.
G. I. Sandle G. Fraser S. Long G. Warhurst 《Pflügers Archiv : European journal of physiology》1990,417(3):259-263
Hydrochloric acid (HCl) secretion by gastric parietal cells involves an apical Cl– conductance, the properties of which have not been defined. In the present study, forskolin and histamine [agonists that increase intracellular cyclic adenosine monophosphate (cAMP)], and dibutyryl cAMP, activated channels in previously quiescent cell-attached membrane patches on cultured human gastric cells (HGT-1). In the cell-attached configuration (Cl–149 mmol/ 1 in bath and pipette), channels exhibited outward rectification, voltage dependence, inward current (–0.7 pA) at zero holding potential and a reversal potential of +24 mV, consistent with the presence of a Cl– conductive pathway. In excised inside-out patches, channels (i) exhibited degrees of outward rectification and voltage dependence that were comparable to those seen in cell-attached patches, (ii) demonstrated a –21 mV shift of their reversal potential when bath Cl– was decreased from 149 mmol/l to 53 mmol/l (calculated Cl–:cation permeability ratio 171), and (iii) were highly sensitive to the Cl– channel blocker diphenylamine-2-carboxylic acid (DPC, 10–3 mol/l). This cAMP-activated Cl– channel bears many similarities to other Cl– channels within intestinal epithalia, and may represent the apical Cl– channel operating in HCl-secreting gastric parietal cells. 相似文献
10.
Ove Christensen Marek Simon Torben Randlev 《Pflügers Archiv : European journal of physiology》1990,415(1):37-46
We have used the patch-clamp technique to characterize three anion channels in the ventricular membrane of the choroid plexus epithelium from Necturus. The most frequently occurring channel had a nonlinear IV-curve. The conductance in excised patches with 112 mM chloride at both sides was 28 pS at 0 mV, increasing towards positive membrane potentials. The selectivity ratios were P
NaP
Cl 0.1 and
. SITS and furosemide (1 mM) on the inside reduces chloride flux to 0.15 and 0.37 times the control value. In attached patches, the most commonly observed channel had a conductance of 7.5 pS. The single-channel current for this channel reversed direction at 15 mV hyperpolarization, indicating accumulation of chloride to a factor of 1.8 above equilibrium. External stimulation of the tissue by theophylline, IBMX and dbcAMP, or by hypotonic shock did not increase the activity of this channel. In very few excised patches, we have observed a chloride channel with a conductance of 7 pS with 112 mM chloride at both sides. The 7 pS channel appears to be identical to a 2 pS channel found in attached patches. The 2 pS channel was not normally active in attached patches but was activated in 28% of the patches by external stimulation. Finally, in few excised patches we have found a 375 pS channel which inactivates within seconds when membrane potential is stepped from 0 mV to a value that differs more than 10–20 mV from zero. The channel did not conduct gluconate but
and P
NaP
Cl 0.1. Internal SITS and furosemide (1 mM) reduced chloride flux to 0.3 and 0.5 times the control value. The channel was never seen in attached patches. The current carried through these channels can not account for the transepithelial steady state Cl–-flux measured by microelectrodes. KCl exit from the cell is suggested to be carried by KCl-cotransport or by channels that are too small to be seen in patch-clamp experiments. 相似文献